EARTHWORM DIVERSITY AND ABUNDANCE IN 
SELECTED DUMPSITES IN IBADAN, AND TOXICITY 
OF CONTAMINATED WATER ON ASSOCIATED 
FAUNA 
 
 
 
BY  
 
 
OLUTOMI ADEOLA ADEWOYIN 
MATRIC NO: 123811 
B.Sc.Ed. (Biology) (Ife), M.Sc. Zoology (Ibadan) 
 
 
A Thesis in the Department of Zoology, 
Submitted to the Faculty of Science  
In partial fulfilment of the requirements for the Degree of  
 
 
DOCTOR OF PHILOSOPHY  
 
of the 
  
UNIVERSITY OF IBADAN 
 
 
AUGUST, 2016  
i 
 
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ABSTRACT 
Huge quantities of wastes which are indiscriminately disposed into uncontrolled 
dumpsites and flowing waters around residential areas are generated from Ibadan, 
metropolis. These may adversely affect soil, surface- and ground-water qualities and 
the fauna. Limited information exists on toxic effects that wastes from these non-
designated sites have on associated fauna. Earthworms are one of the dominant fauna 
in soils and are pollution bioindicators. Therefore this study was designed to 
investigate physico-chemical parameters, earthworm diversity and abundance, and 
acute toxicity of contaminated-water on some fauna in selected dumpsites in Ibadan. 
 
One-hundred and twenty water samples from streams (Irefin, Gege, Gbagi, Odinjo, 
and Omi-Adio) receiving domestic wastes; 60-composite soil samples each from 
dumpsites (Ojokondo, Olodo, Moniya, Idi-Ope and Oremeji) and stream banks; 12-
composite soil samples from a control site at University of Ibadan (UI); 72 
groundwater samples from wells around the dumpsites and UI were purposively 
collected once every two months from March 2008 to February 2010. Earthworms 
2
from top-soil were sampled using 0.25x0.25 m  quadrat, handpicked, identified and 
density determined following standard procedures. Earthworm species’ diversity and 
evenness were determined using Shannon-Wiener diversity index and Shannon’s 
evenness, respectively. Water samples were analysed for physico-chemical 
parameters [including Dissolved-Oxygen (DO), Biochemical-Oxygen-Demand 
(BOD), and Chemical-Oxygen-Demand (COD)] and soil samples including lead and 
zinc using standard methods and results were compared with NESREA standards.  
The 48-hour-LC50 of stream-samples were determined for Cloeon perkinsi (mayfly) 
larvae (CP); while 96-hour-LC50 for Rana temporaria tadpoles, Clarias gariepinus 
frys (CG1) and fingerlings (CG2) were determined using Probit method. Data were 
analysed using descriptive statistics and ANOVA at p=0.05.  
 
Three earthworm species (Eudrilus euginiae, Dichogaster modigliani and 
Hyperiodrilus africanus) were identified at UI, streams and dumpsites. Highest 
2
density of Eudrilus euginiae (30.0±13.7/m ) was recorded at UI and this was 
2
significantly different from other sites, while lowest (6.4±2.2/m ) was recorded at 
2
Ojokondo. Highest densities of Hyperiodrilus africanus (32.7±14.6/m ) and 
2
Dichogaster modigliani (40.0±0.0/m ) were recorded at UI and Gbagi, respectively; 
2
while lowest value of 4.0±0.0/m  was recorded at Irefin and Gege. Eudrilus euginiae 
 
 
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and Dichogaster modigliani were not found at Gege and Idi-Ope, respectively, while 
Hyperiodrilus africanus was not found at Odinjo, Moniya and Olodo. Earthworm 
diversity (0.5) was highest in UI and lowest (0.3) at Gege. Earthworms were most 
evenly distributed at Odinjo (2.4) and least at Ojokondo (0.8). The DO (mg/L) for 
streams ranged from (0.4±0.4) to (2.6±0.6) and were lower than permissible limit for 
aquatic life. Lead (260.6±77.7mg/kg, 269.6±46.4mg/kg) and zinc (456.9±69.9mg/kg, 
1685.1±420.3mg/kg) values in Gege and Ojokondo soils, respectively were 
significantly higher than NESREA limits. In all groundwater samples, BOD 
(46.7±21.0mg/L) and COD (154.0±7.0mg/L) exceeded NESREA limits. The 48-hour-
LC50 of stream-water to CP (Irefin, 12.7%; Gege, 8.6%), and 96-hour-LC50 to CGI 
(Gege, 0.8%; Gbagi, 2.8%) and CG2 (Gege, 3.3%; Irefin, 0.6%) indicated high 
toxicity of the sites.  
 
The low earthworm abundance, poor physico-chemical qualities and high toxicity of 
the study sites revealed that the soil, streams and groundwater were polluted in 
Ibadan. Consequently, there is need for adequate management and disposal of solid-
wastes to prevent further environmental contamination. 
Keywords: Uncontrolled dumpsites in Ibadan, Earthworm abundance, Physico-
chemical qualities, Acute toxicity.                                                                                                                 
Word count: 500 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
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ACKNOWLEDGEMENTS 
My appreciation goes to the Lord Almighty for seeing me through the period of this 
research work, for his faithfulness, provision and journey mercies He granted me 
throughout the period. 
I am greatly indebted to my supervisor, Professor A. T. Hassan for his constructive 
criticism, unflinching support and reposing great confidence in my ability to carry out 
this wok. I deeply appreciate the support and assistance of Dr Adeola Oni of the 
Department of Zoology, University of Ibadan, all academic staff of the Department, 
the Postgraduate committee of the Department and Faculty and the Heads of 
Department during my period of study. 
The assistance on the field and laboratory works, encouragement, financial, moral, 
and emotional support given to me by my loving husband Muyiwa Adeyemi-Ale is 
highly appreciated. I am also indebted to Dr A. A Aladesida of the Department of 
Biological Sciences, Federal University of Agriculture, Abeokuta for his assistance on 
the field, identification of the earthworms and statistical analysis. 
I acknowledge Prof Sylvester Ogbogu of the Department of Zoology, Obafemi 
Awolowo University, Ile –Ife on his assistance on the collection of Cloeon perkinsi 
(mayfly) larvae and also his words of encouragement. I am also grateful to Dr Efere 
Obuotor of Biochemistry Department, Obafemi Awolowo University, Ile –Ife on his 
assistance and the use of his laboratory for the toxicity tests. 
I appreciate Dr O. D. Owolabi for creating time out for me on the assistance of 
reading through my abstract, his prayers and words of encouragement. 
I wish to thank my parents Late Venerable R. O Adewoyin and Mrs T. E. Adewoyin 
for their prayers, support, encouragement and especially to my mum who helped me 
out to use her laboratory at the Department of Pharmaceutical Chemistry, Obafemi 
Awolowo University, Ile –Ife for the analysis of the physico-chemical parameters of 
soil, streams and groundwater samples. I also appreciate the entire laboratory staff of 
the Department and the Heads of Department during those periods. 
 
 
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I thank my children Iyanuoluwa and Iyinnifoluwa for cooperating and understanding 
with me during the course of the study. I appreciate my siblings and Mrs Bunmi 
Babatunde for taking care of my children during those times I was not available. 
Lastly, I thank the Administration of University of Ilorin for granting me staff 
development study leave and also the past Heads of Department of Zoology, 
University of Ilorin for releasing me to enjoy the programme. 
 
 
  
 
 
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CERTIFICATION 
 
I certify that this work was carried out by Olutomi Adeola ADEWOYIN in 
the Department of Zoology, University of Ibadan 
 
 
 
 
---------------------------------------------------- 
Supervisor 
A. T. Hassan, 
B.Sc., Ph.D. (Ibadan) 
Professor, Department of Zoology 
University of Ibadan, Nigeria 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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DEDICATION 
This research work is dedicated to my late dad, Venerable Rufus Olubukola 
Adewoyin and to my late uncle, Elijah Obafemi Adewoyin. The two of them believed 
in me but unfortunately death took them away, not to see the heights I will attain. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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TABLE OF CONTENTS 
Title            
Title page          i 
Abstract          ii 
Acknowledgement         iv 
Certification          vi 
Dedication          vii 
Table of contents         viii 
List of Tables          xvii 
List of Figures                    xviii 
List of Plates          xxi 
List of Appendices         xxii 
CHAPTER ONE 
Introduction       
1.1  Waste         1 
1.2  Solid waste         1 
1.3  Categories of solid wastes      3 
1.4  Solid waste disposal patterns      3 
1.5  Solid waste contamination of soil, surface water and  
groundwater         6 
1.5.1  Soil         6 
1.5.2  Surface water        7 
1.5.3  Groundwater        8 
1.6  Impacts of solid waste and leachate on organisms   10 
1.7  Ibadan city         11 
1.8  Justification        11 
1.9  Aim of the study       12 
1.10  Objectives        12 
CHAPTER TWO 
Literature Review 
2.1  Solid Waste: Definition and Generation    13 
2.2  Refuse storage       14 
2.3  Treatment and movement of household refuse and market  
wastes         15 
 
 
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2.4  Earthworms, environmental factors and contaminastion  15  
2.5  Impacts of solid waste on soil      17 
2.6  Impacts of municipal solid wastes and leachate on terrestrial  
organisms        20 
2.7   Mayflies and contamination      22 
2.8  Tadpoles and contamination      24 
2.9   Fish and contamination      25 
2.10  Impacts of solid waste on physico–chemical qualities of  
water         27 
CHAPTER THREE 
Materials and Methods 
3.1  Description of the Study Area     29 
3.1.1  Sampling Sites       30 
3.2  Sampling        44 
3.2.1  Sampling, preservation and identification of collected earthworm 
  samples        44 
3.2.2  Sampling, preservation and analytical methods for collected  
stream water        48 
3.2.2.1  Physico-chemical analysis      48 
3.2.2.1.1 pH         48 
3.2.2.1.2 Electrical conductivity      48 
3.2.2.1.3 Total dissolved solids       48 
3.2.2.1.4 Dissolved oxygen       48 
3.2.2.1.5 Biochemical oxygen demand (BOD)     49 
3.2.2.1.6 Chemical Oxygen Demand (COD)     49 
3.2.2.1.7 Total alkalinity       49 
3.2.2.2  Anions         50 
3.2.2.2.1 Chloride        50 
3.2.2.2.8 Phosphate-phosphorus      50 
3.2.2.2.3 Nitrate-nitrogen       50 
3.2.2.2.4 Sulphate-sulphur       51 
3.2.2.3  Cations (Calcium and Magnesium)     51 
3.2.2.4  Trace and heavy metals       51 
3.2.3  Sampling, processing and analytical methods for collected soil 52 
 
 
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3.2.3.1  Particle size distribution      52 
3.2.3.2  pH         53 
3.2.3.3  Electrical conductivity      54 
3.2.3.4  Total organic carbon and matter     54 
3.2.3.5  Anions         54 
3.2.3.5.1 Nitrate         54 
3.2.3.5.2 Sulphate        55 
3.2.3.6  Cations        55 
3.2.3.7  Cation exchange capacity (CEC)     56 
3.2.3.8  Trace and heavy metals      56 
3.2.4  Sampling, preservation and analytical methods for  
collected groundwater       56 
3.2.5  Toxicity assays       57 
3.2.5.1  Mayflies toxicity assay      57 
3.2.5.2   Tadpoles bioassay       57 
3.2.5.3   Fish toxicity assay       58 
3.2.5.3.1  Clarias gariepinus frys toxicity assay    58 
3.2.5.3.2 Clarias gariepinus fingerlings toxicity assay    58 
3.2.5.4  Earthworms’ toxicity assay      59 
3.3  Analytical procedures for stream water, soil and groundwater 59 
3.3.1  Cations, trace and heavy metals determination in soil samples: 
 sample digestion       60 
3.3.2  Cations, trace and heavy metals determination in stream water:  
sample digestion       60 
3.4  Statistical analysis       61 
3.4.1  Biological parameters       61 
3.4.1.1  Shannon Wiener’s diversity index     61 
3.4.1.2  Shannon’s Evenness measures     61 
3.4.1.3  Menhinick’s index       61 
3.4.1.4  Sorensen’s coefficient (quotient of similarity)   61 
3.4.2  Graphical illustrations and descriptive statistics   62 
3.4.3  Physico-chemical parameters      62 
3.4.3.1  ANOVA (Analysis of variance)     62 
3.4.3.2  Duncan’s multiple range tests     62 
 
 
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3.4.3.3  Pearson’s correlation coefficient     62 
3.4.4  Toxicity Assay       62 
CHAPTER FOUR 
Results 
4.1  Earthworms composition and abundance during the study 
period         63 
4.1.1  Streams        63 
4.1.2  Dumpsites        65 
4.2  Earthworms’ density and biomass      68 
4.2.1  Streams        68 
4.2.2  Dumpsites        70 
4.3  Earthworms’ diversity      71 
4.3.1   Streams        71 
4.3.2  Dumpsites        71 
4.4  Result of analysis of stream water samples     74 
4.4.1     Bimonthly variation of physico-chemical characteristics of stream  
samples        74 
4.4.1.1  Hydrogen ion concentration (pH)     74 
4.4.1.2  Dissolved oxygen (DO)      78 
4.4.1.3  Biochemical oxygen demand (BOD)     79 
4.4.1.4  Chemical oxygen demand (COD)     79 
4.4.1.5  Total dissolved solids (TDS)      82 
4.4.1.6  Electrical conductivity (EC)      82 
4.4.1.7  Total alkalinity       85 
4.4.2  Bimonthly variation of anions of stream water samples  88 
4.4.2.1  Chloride        88 
4.4.2.2  Phosphate – phosphorus      88 
4.4.2.3  Nitrate – nitrogen       90 
4.4.2.4  Sulphate - sulphur       92 
4.4.3  Bimonthly variation of cations of stream water samples  94 
4.4.3.1  Calcium        94 
4.4.3.2  Magnesium        97 
4.4.4  Bimonthly variation of trace and heavy metals of  
stream water samples       97 
 
 
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4.4.4.1  Iron         97 
4.4.4.2  Manganese        99 
4.4.4.3  Copper        101 
4.4.4.4  Zinc         101 
4.4.4.5  Lead          104 
4.4.4.6  Cadmium        106 
4.4.4.7  Nickel         108 
4.4.4.8  Chromium        110 
4.5  Result of analysis of soil samples from the streams   110 
4.5.1 Bimonthly variation of physico-chemical characteristics of soil  
samples from the streams      110 
4.5.1.1  Soil particle size distribution      113 
4.5.1.2  Hydrogen ion concentration (pH)     113 
4.5.1.3  Electrical Conductivity      115 
4.5.1.4  Total organic carbon       115 
4.5.1.5  Total Organic Matter       116 
4.5.2  Bimonthly variation of anions of soil samples from the streams 116 
4.5.2.1  Nitrate – nitrogen       116 
4.5.2.2  Sulphate – sulphur       118 
4.5.3 Bimonthly variation of cations of soil samples from the  
banks of streams       118 
4.5.3.1  Phosphorus        119 
4.5.3.2  Calcium        119 
4.5.3.3  Magnesium        120 
4.5.3.4  Sodium        120 
4.5.3.5  Potassium        120 
4.5.3.6  Cation exchange capacity (CEC)     122 
4.5.4  Bimonthly variation of trace and heavy metals of soil samples  
from the banks of streams      124 
4.5.4.1  Iron         124 
4.5.4.2  Manganese        124 
4.5.4.3  Copper        125 
4.5.4.4  Zinc         125 
4.5.4.5  Lead          126 
 
 
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4.5.4.6  Cadmium        126 
4.5.4.7  Nickel         128 
4.5.4.8  Chromium        128 
4.6  Result of analysis of soil samples from the dumpsites  129 
4.6.1  Bimonthly variation of physico-chemical characteristics of soil  
samples from the dumpsites      129 
4.6.1.1  Soil particle size distribution      129 
4.6.1.2  Hydrogen ion concentration (pH)     131 
4.6.1.3  Electrical conductivity      131 
4.6.1.4  Total organic carbon       131 
4.6.1.5  Total Organic Matter       133 
4.6.2  Bimonthly variation of anions of soil samples from the  
dumpsites        133 
4.6.2.1  Nitrate-nitrogen       133 
4.6.2.2  Sulphate – sulphur       135 
4.6.3  Bimonthly variation of cations of soil samples from the  
dumpsites        136 
4.6.3.1  Phosphorus        136 
4.6.3.2  Calcium        136 
4.6.3.3  Magnesium        138 
4.6.3.4  Sodium         138 
4.6.3.5  Potassium        138 
4.6.3.6  Cation exchange capacity      139 
4.6.4  Bimonthly variation of trace and heavy metals of soil samples  
from the dumpsites       139 
4.6.4.1  Iron         139 
4.6.4.2  Manganese        141 
4.6.4.3  Copper        141 
4.6.4.4  Zinc         142 
4.6.4.5  Lead          142 
4.6.4.6  Cadmium        142 
4.6.4.7  Nickel         144 
4.6.4.8  Chromium        144 
4.7  Result of analysis of groundwater samples close to the streams 145 
 
 
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4.7.1 Bimonthly variation of physico-chemical characteristics of  
groundwater samples close to the streams    145 
4.7.1.1  Hydrogen ion concentration (pH)     145 
4.7.1.2  Biochemical oxygen demand (BOD)     145 
4.7.1.3  Chemical oxygen demand (COD)     147 
4.7.1.4  Total dissolved solids (TDS)      147 
4.7.1.5  Electrical conductivity (EC)      147 
4.7.1.6  Total Alkalinity       147 
4.7.2  Bimonthly variation of anions of groundwater samples close to  
the streams        149 
4.7.2.1  Chloride        149 
4.7.2.2  Phosphate – phosphorus      149 
4.7.2.3  Nitrate – nitrogen       149 
4.7.2.4  Sulphate - sulphur       150 
4.7.3  Bimonthly variation of cations of groundwater samples close  
to the streams        150 
4.7.3.1  Calcium        150 
4.7.3.2  Magnesium        150 
4.7.4  Bimonthly variation of trace and heavy metals of groundwater  
samples close to the streams      150 
4.7.4.1  Iron         153 
4.7.4.2  Manganese        153 
4.7.4.3  Copper        153 
4.7.4.4  Zinc         153 
4.7.4.5  Lead          154 
4.7.4.6  Cadmium        154 
4.7.4.7  Nickel         154 
4.7.4.8  Chromium        156 
4.8  Result of analysis of groundwater samples around the dumpsites 156 
4.8.1 Bimonthly variation of physico-chemical characteristics of  
groundwater samples around the dumpsites    156 
4.8.1.1  Hydrogen ion concentration (pH)     156 
4.8.1.2  Biochemical oxygen demand (BOD)     158 
4.8.1.3  Chemical oxygen demand (COD)     158 
 
 
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4.8.1.4  Total dissolved solids (TDS)      159 
4.8.1.5  Electrical conductivity (EC)      159 
4.8.1.6  Total alkalinity       161 
4.8.2 Bimonthly variation of anions of groundwater samples 
 around the dumpsites       161 
4.8.2.1  Chloride        161 
4.8.2.2  Phosphate – phosphorus      162 
4.8.2.3  Nitrate – nitrogen       162 
4.8.2.4  Sulphate - sulphur       164 
4.8.3   Bimonthly variation of cations of groundwater samples  
around the dumpsites       164 
4.8.3.1  Calcium        164 
4.8.3.2  Magnesium        165 
4.8.4  Bimonthly variation of trace and heavy metals of groundwater 
samples around the dumpsites     167 
4.8.4.1  Iron         167 
4.8.4.2  Manganese        167 
4.8.4.3  Copper        168 
4.8.4.4  Zinc         168 
4.8.4.5  Lead          169 
4.8.4.6  Cadmium        171 
4.8.4.7  Nickel         172 
4.8.4.8  Chromium        172 
4.9  Toxicity assays       173 
4.9.1  Earthworms’ toxicity assay      173 
4.9.1.1 Streams        173 
4.9.1.2 Dumpsites        173 
4.9.2  Mayflies toxicity assay      175  
4.9.3  Tadpoles bioassay       177 
4.9.4  Fish toxicity assay       177 
4.9.4.1 Clarias gariepinus frys toxicity assay    177 
4.9.4.2 Clarias gariepinus fingerlings bioassay    182 
 
CHAPTER FIVE 
 
 
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Discussion 
5.1  Earthworm diversity and abundance and relationship with soil  
factors         184 
5.2  Physico–chemical characteristics of stream samples   189 
5.2.1  Anion qualites of stream water     192 
5.2.2  Calcium and magnesium      193 
5.2.3a  Other metals (Pb, Cu, Fe, Zn, Ni, Cd, Cr, Mn)   193 
5.2.3b  Other metals Ni, Cd, Cr, Mn      196 
5.3  Soil contamination by domestic solid waste    197 
5.3.1  Particle size distribution      197 
5.3.2  Organic matter       197 
5.3.3  Electrical conductivity      198 
5.3.4  Calcium and magnesium      198 
5.3.5   Metals         200 
5.4  Groundwater contamination by domestic solid wastes  202 
5.4.1  Calcium and magnesium      207 
5.4.2  Other metals (Pb, Cu, Fe, Zn, Ni, Cd, Mn and Cr)   207 
5.5  Toxicity tests        210 
5.5.1  Eudrilus euginiae earthworms     210 
5.5.2  Mayflies (Cloeon perkinsi’s) larvae     211 
5.5.3  Tadpoles (Rana temporaria)      212 
5.5.4   Fishes (Frys and fingerlings of Clarias gariepinus)   214 
5.6  Conclusion and recommendation     216 
REFERENCES         219 
APPENDICES         262 
 
  
 
 
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LIST OF TABLES 
Table 4.1:  Diversity indices of earthworms observed at the streams   72 
Table 4.2:  Sorensen’s coefficient of similarity for streams’ earthworms 73 
Table 4.3:  Diversity indices of earthworms observed at the dumpsites   75 
Table 4.4:  Sorensen’s coefficient of similarity for dumpsites’ earthworms 76 
Table 4.5:  Mortalities of tadpoles to different concentrations of Gege stream  
water         179 
Table 4.6:  Mortalities of Clarias gariepinus fingerlings to different  
Concentrations of Gege and Irefin stream water samples  1 
 
 
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LIST OF FIGURES 
Figure 3.1: The map of Ibadan showing the sampling stations   31 
Figure 4.1: a) Percentage abundance of earthworms at the streams’ banks  66 
        b) Seasonal variation of earthworm species at the streams’ banks 
Figure 4.2: a) Percentage abundance of earthworms at the dumpsites  69 
        b) Seasonal variation of earthworm species at the dumpsite 
Figure 4.3: Bimonthly variation of pH values of streams     
(a) Upstream  (b) Downstream      77 
Figure 4.4: Bimonthly variation of dissolved oxygen (DO) values of streams               
(a) Upstream  (b) Downstream      80 
Figure 4.5: Bimonthly variation of biochemical oxygen demand (BOD) values of 
streams                                    (a) Upstream  (b) Downstream  81 
Figure 4.6: Bimonthly variation of chemical oxygen demand (COD) values of streams                                    
(a) Upstream  (b) Downstream      83 
Figure 4.7: Bimonthly variation of total dissolved solids (TDS) values of streams 
(a) Upstream  (b) Downstream      84 
Figure 4.8: Bimonthly variation of electrical conductivity (EC) values of streams                                
(a) Upstream  (b) Downstream      86 
Figure 4.9: Bimonthly variation of total alkalinity values of streams                                 
(a) Upstream  (b) Downstream       87 
Figure 4.10: Bimonthly variation of chloride values of streams 
(a) Upstream  (b) Downstream      89 
Figure 4.11: Bimonthly variation of phosphate values of streams 
(a) Upstream  (b) Downstream      91 
Figure 4.12: Bimonthly variation of nitrate values of streams 
 (a) Upstream  (b) Downstream      93 
Figure 4.13: Bimonthly variation of sulphate values of streams  
 (a) Upstream  (b) Downstream      95 
Figure 4.14: Bimonthly variation of calcium values of streams 
(a) Upstream  (b) Downstream      96 
Figure 4.15: Bimonthly variation of magnesium values of streams  
 (a) Upstream  (b) Downstream      98 
Figure 4.16: Bimonthly variation of iron values of streams  
(a) Upstream  (b) Downstream      100 
 
 
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Figure 4.17: Bimonthly variation of manganese values of streams  
(a) Upstream  (b) Downstream      102 
Figure 4.18: Bimonthly variation of copper values of streams  
(a) Upstream  (b) Downstream      103 
Figure 4.19: Bimonthly variation of zinc values of streams  
(a) Upstream  (b) Downstream      105 
Figure 4.20: Bimonthly variation of lead values of streams 
(a) Upstream  (b) Downstream      107 
Figure 4.21: Bimonthly variation of cadmium values of streams  
(a) Upstream  (b) Downstream      109 
Figure 4.22: Bimonthly variation of nickel values of streams  
(a) Upstream  (b) Downstream      111 
Figure 4.23: Bimonthly variation of chromium values of streams  
(a) Upstream  (b) Downstream      112 
Figure 4.24: Bimonthly variation of particle size distribution values of soil from 
streams’ banks   (a) Sand        (b)  Silt       (c) Clay   114 
Figure 4.25: Bimonthly variation of physico-chemical values of soil from streams’ 
banks   (a) pH        (b)  EC       (c) TOC     (d) TOM    117 
Figure 4.26: Bimonthly variation of some anions and some cations values of soil  
2-
from stream banks     (a) NO3 - N  (b)  SO4  – S  (c) P  (d) Ca    121 
Figure 4.27: Bimonthly variation of some cations values and cation exchange 
capacities of soil from streams’ banks  (a) Mg     (b) Na (c) Na     (d) CEC  123 
Figure 4.28: Bimonthly variation of trace and heavy metal values of soil from 
streams’ banks    (a) Fe        (b) Mn       (c) Cu  (d) Zn   127 
Figure 4.29: Bimonthly variation of trace and heavy metals values of soil  
from streams’ banks   (a) Pb   (b) Cd       (c) Ni (d) Cr   130 
Figure 4.30: Bimonthly variation of particle size distribution values of soil  
from dumpsites (a) Sand       (b) Silt      (c) Clay    132 
Figure 4.31: Bimonthly variation of physico-chemical values of soil from 
 dumpsites (a) pH        (b)  EC       (c) TOC (d) TOM   134 
Figure 4.32: Bimonthly variation of some anions and cations values of soil from 
dumpsites (a) NO3 - N        (b)  SO4 - S       (c) P (d) Ca  137 
Figure 4.33: Bimonthly variation of cations values and cation exchange capacities 
 of soil from dumpsites (a) Mg     (b) Na   (c) K       (d) CEC   140 
 
 
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Figure 4.34: Bimonthly variation of some trace and heavy metals of soil  
from dumpsites   (a) Fe      (b) Mn             (c) Cu            (d)   Zn  143 
Figure 4.35: Bimonthly variation of some trace and heavy metals of soil  
from dumpsites    (a) Pb  (b) Cd           (c) Ni         (d)  Cr   146 
Figure 4.36: Bimonthly variation of physico-chemical characteristics of  
groundwater samples close to streams (a) pH  (b) BOD    (c) COD  (d)  TDS 148 
Figure 4.37: Bimonthly variation of some physico-chemical characteristics and  
some anions of groundwater samples close to streams (a) EC    
 (b) Total alkalinity    (c) Chloride        (d)  Phosphate – phosphorus  151 
Figure 4.38: Bimonthly variation of some anions and some cations of groundwater 
- 2-
samples close to streams (a) NO3  - N    (b) SO4  - S   (c) Ca  (d)  Mg  152 
Figure 4.39: Bimonthly variation of some trace and heavy metals of  
groundwater samples close to streams  (a) Fe  (b) Mn      (c) Cu    (d)  Zn  155 
Figure 4.40: Bimonthly variation of some trace and heavy metals of  
groundwater samples close to streams  (a) Pb    (b) Cd   (c) Ni  (d) Cr 157 
Figure 4.41: Bimonthly variation of physico-chemical of groundwater samples 
close to dumpsites  (a) pH         (b) BOD      (c) COD       (d) TDS 160 
Figure 4.42: Bimonthly variation of some physico-chemical characteristics and 
 some anions of groundwater samples close to streams (a) EC    
(b) Total alkalinity    (c) Chloride        (d)  Phosphate – phosphorus              163 
Figure 4.43: Bimonthly variation of some anions and some cations of  
- 2-
Groundwater close to dumpsites (a) NO3  - N    (b) SO4  - S   (c) Ca  (d)  Mg 166 
Figure 4.44: Bimonthly variation of some trace and heavy metals of 
 groundwater samples close to dumpsites (a) Fe    (b) Mn   (c) Cu  (d)  Zn  170 
Figure 4.45: Bimonthly variation of some trace and heavy metals of  
groundwater samples close to dumpsites (a) Pb    (b) Cd   (c) Ni  (d)  Cr  174 
Figure 4.46 
a): Effect of dumpsites' soil on eudrilus euginiae survival     176 
b): Effect of streams' soil on eudrilus euginiae survival   
Figure 4.47: Mortalities of Cloeon perkinsi’s larvae exposed to    178 
different concentrations of stream water 
Figure 4.48: Mortalities of Clarias gariepinus frys larvae exposed to   182 
different concentrations of stream water 
 
 
 
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LIST OF PLATES 
Plate 3.1: Irefin stream       33 
Plate 3.2: Gege stream       34 
Plate 3.3: Gbagi stream       35  
Plate 3.4: Odinjo stream       37 
Plate 3.5:  Omi Adio stream      38 
Plate 3.6: Ojokondo dumpsite      40 
Plate 3.7 Olodo dumpsite      41 
Plate 3.8:  Moniya dumpsite       42 
Plate 3.9: Idi Ope dumpsite      43 
Plate 3.10:  Oremeji dumpsite      45 
Plate 3.11:  Control stream (Awba Stream, UI)     46 
Plate 3.12:  Control site for land dumpsite (Tafawa Balewa Hall, UI) 47 
Plate 4.1 Earthworms encountered at the streams and    64 
dumpsites during the study period   
 
 
 
 
 
 
 
 
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LIST OF APPENDICES 
1. Details of earthworms found at the banks of the streams during the sampling 
period  
2. Seasonal variations of earthworms observed at the banks of the streams 
3. Details of earthworms found in the soils from the dumpsites during the 
sampling period 
4. Seasonal variations of earthworms observed at the dumpsites 
5. The range and mean values of the physico-chemical characteristics and anions 
of stream water samples from March 2008 to January 2010 
6. The range and mean values of the cations, trace and heavy metals of stream 
water samples from March 2008 to January 2010 
7. ANOVA table of physico-chemical characteristics, anions, cations, trace and 
heavy metals of stream water samples 
8. Duncan tests of physico - chemical values, anions, cations, trace and heavy 
metals of stream water samples 
9. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Irefin upstream water samples 
10. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Irefin downstream water samples 
11. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Gege upstream water samples 
12. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Gege downstream water samples 
13. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Gbagi upstream water samples 
14. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Gbagi downstream water samples 
 
 
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15. Monthly values of physico-chemical characteristics, anions, cat343ions, trace 
and heavy metals of Odinjo upstream water samples 
16. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Odinjo downstream water samples 
17. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Omi Adio upstream water samples 
18. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Omi Adio downstream water samples 
19. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of Awba stream water samples (control) 
20. The range and mean values of physico-chemical characteristics of soil samples 
from the banks of streams from March 2008 to January 2010 
21. Soil textural classification triangle 
22. The range and mean values of anions and cations of soil samples from the 
banks of streams from March 2008 to January 2010 
23. The range and mean values of trace and heavy metals of soil samples from the 
banks of streams from March 2008 to January 2010 
24. ANOVA table of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from the banks of streams 
25. Duncan tests of physico - chemical values, anions, cations, trace and heavy 
metals of soil samples from the banks of streams 
26. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from Irefin stream bank during the study period 
27. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from Gege stream bank during the study period 
28. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from Gbagi stream bank during the study period 
29. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from Odinjo stream bank during the study period 
30. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from Omi Adio stream bank during the study 
period 
31. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from Awba stream bank during the study period 
 
 
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32. The range and mean values of physico-chemical characteristics of soil samples 
from dumpsites from April 2008 to February 2010 
33. The range and mean values of anions and cations of soil samples from 
dumpsites from April 2008 to February 2010 
34. The range and mean values of trace and heavy metals of soil samples from 
dumpsites from April 2008 to February 2010 
35. ANOVA table of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from the dumpsites 
36. Duncan tests of physico - chemical values, anions, cations, trace and heavy 
metals of soil samples from dumpsites 
37. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from the Ojokondo dumpsite during the sudy 
period 
38. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from the Olodo dumpsite during the sudy period 
39. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from the Moniya dumpsite during the sudy 
period 
40. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from the Idi Ope dumpsite during the sudy 
period 
41. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from the Oremeji dumpsite during the sudy 
period 
42. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of soil samples from the Balewa Hall during the sudy period 
43. The range and mean values of the physico-chemical characteristics of 
groundwater samples close to the streams  
44. The range and mean values of the anions and cations of groundwater samples 
close to the streams from March 2008 to January 2010  
45. The range and mean values of the trace and heavy metals of groundwater 
samples close to the streams from March 2008 to January 2010 
46. T - test of physico-chemical characteristics, anions, cations, trace and heavy 
metals of the groundwater samples close to the streams 
 
 
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47. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) close to Gege stream during the study 
period  
48. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) close to Odinjo stream during the 
study period 
49. The bimonthly variation of the physico-chemical analysis of groundwater 
samples close to the dumpsites from April 2008 to February 2010. 
50. The range and mean values of the anions and cations of groundwater  (well) 
samples around the dumpsites from April 2008 to February 2010 
51. The range and mean values of the trace and heavy metals of groundwater 
(well) samples around the dumpsites from April 2008 to February 2010 
52. ANOVA table of physico-chemical characteristics, anions, cations, trace and 
heavy metals of groundwater (well) samples close to the dumpsites 
53. Duncan tests of physico - chemical values, anions, cations, trace and heavy 
metals groundwater (well) samples close to the dumpsites  
54. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) before the Ojokondo dumpsite during 
the study period 
55. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) after the Ojokondo dumpsite during 
the study period 
56. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) close to the Olodo dumpsite during the 
study period 
57. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) close to the Moniya dumpsite during 
the study period 
58. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) close to the Idi Ope dumpsite during 
the study period 
59. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) close to the Oremeji dumpsite during 
the study period 
 
 
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60. Monthly values of physico-chemical characteristics, anions, cations, trace and 
heavy metals of the groundwater (well) close to the Balewa Hall (control) 
during the study period 
61. The result of the Eudrilus euginiae earthworms exposed to the soil from the 
streams’ banks 
62. The result of the Eudrilus euginiae earthworms exposed to the soil from 
dumpsites 
63. thAcute toxicity of contaminated downstream water samples on 9  instar larvae 
of Cloeon perkinsi 
64. Acute toxicity of contaminated Gege downstream water sample on tadpoles of 
Rana temporaria   
65. Acute toxicity of contaminated downstream water samples on frys of Clarias 
gariepinus  
66. Acute toxicity of contaminated downstream water samples on fingerlings of 
Clarias gariepinus  
67. Correlation coefficient matrix of streams’ soil samples, earthworms’ density 
and biomass 
68. Correlation coefficient matrix of dumpsites’ soil samples, earthworms’ density 
and biomass 
69. Correlation coefficient matrix of streams’ physico-chemical qualities, anions, 
cations, trace and heavy metals. 
70. Correlation coefficient matrix of groundwaters’ physico-chemical qualities, 
anions, cations, trace and heavy metals. 
71. Water classification according to Davis and DeWiest (1966) 
72. Water classification according to Carroll (1962) and Freeze and Cherry (1979) 
73. Water classification based on salinity hazards according to US laboratory
 (1954) 
 
 
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CHAPTER ONE 
INTRODUCTION 
1.1 Waste  
Wastes are substances or objects which are disposed off or are intended to be disposed 
off or are required to be disposed off by the provisions of national laws (Basel 
Convention, 1989). They are unwanted residues that are usually perceived to be of 
negative value (Hamer, 2003). According to Taylor and Allen (2006), waste can be 
loosely defined as any material that is considered to be of no further use to the owner, 
hence discarded. It is generated universally and is a direct consequence of all human 
activities. It can also be defined as any unavoidable material resulting from an 
activity, which has no immediate economic demand and which must be disposed off 
(NISP, 2003). The major classification of wastes include solid, liquid and gaseous. 
Solid waste as defined by Olexa et al. (2003) includes garbage, refuse, yard trash, 
clean debris, white goods, special waste, ashes, residuals (sludge), solid, or semi-solid 
material, or contained gaseous material. The definition specifically includes 
agricultural, commercial, domestic, governmental, and mining wastes. The definition 
specifically excludes pollution. Liquid wastes are wastes dissolved in water 
emanating from industrial processes known as effluent, domestic liquid, acid waste 
and waste oil from workshop (NISP, 2003). While gaseous wastes are waste 
substances in the air (neither solid nor liquid) and they move freely to fill any 
available space. These include wastes resulting from gas flaring, particulate dust, 
waste gases from stack, cement factories, stone crushing, excavation activities, lime 
dust, asbestos dust, acid fumes from automobiles and cigarette fumes (NISP, 2003). 
1.2 Solid waste 
Solid wastes as defined by Omofonmwan and Eseigbe (2009) are residual from 
homes, businesses and institutions and are referred to as trash, garbage, rubbish, 
refuse, discards and throwaways that are no longer of any relevance to the disposer. 
 
 
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Solid waste also means unwanted materials or substances that are left or discarded 
after use, also included are by-products of process lines or materials that may be 
required by law to be disposed off (Okecha, 2000).  
According to Omofonmwan and Eseigbe (2009), solid waste can be classified in a 
number of ways, on the basis of source, environmental risks, utility and physical 
property. On the basis of source which is commonly used, solid wastes are classified 
as: municipal solid wastes, industrial solid wastes, agricultural solid wastes, mining 
and mineral wastes, construction and demolition wastes, healthcare wastes, 
radioactive (nuclear) wastes, human and animal wastes. 
Improved standard of living contributes to increased quantities of solid wastes 
(Pandard et al., 2006). In the core, rural or local areas, there are high quantities of 
organic wastes like leaves used for wrapping food, faeces, and so on, while in the high 
class areas there are huge quantites of metallic wastes like tins for packaged or 
processed food. The generation of solid waste from household, industries, markets, 
abattoir and shops result in improving the standard of living of the inhabitants 
(Omofonmwan and Eseigbe, 2009).  
Solid-waste generation and composition in Ibadan is at the rate of 153/Kg/pers./year 
with paper 15%, food 43%, plastics 4%, glass 6%, metals 21%, textiles 1% and other 
wastes 10% (Onibokun and Kumuyi, 1999). Oni (2010) also observed solid waste 
composition in Aba-eku landfill in Ibadan to constitute polyethylene plastics 11.5 %, 
rigid plastics 3.76 %, papers 17.59 %, glass or ceramics 6.62 %, metals 24.79% , food 
wastes 6.49 %, biodegradable humus 5.86 %, textiles 3.39 %, leather 2.29 %, wood, 
bones and straw 2.24 %, health care wastes 2.07 %, rubber 2.07 %, construction 
materials 1.58 %, car parts 0.30 %, polystyrene packaging plastics 0.21 % and 
miscellaneous fraction 9.25 %. Amber et al. (2012) observed solid wastes 
composition in Ibadan to include food/organics 58.5 %, paper/polythene 37.6 %, 
textile 1.4 %, glass and metal 0.6 %, others (dust, ash, rubber, soil, bones, ceramics 
8.9 % and moisture content 23.52 %. 
Literatures from different research studies indicated that urban areas produce more 
waste than the rural areas and this might be as a result of the high income that is being 
generated by the urban dwellers and also a lot of industries being located in urban 
areas (Ogu, 2000; Babanyara et al., 2010; Aliyu, 2011). 
 
 
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1.3 Categories of solid wastes  
Solid wastes have been categorized by various authors.  According to Hamer (2003), 
some of the main categories of solid waste include: municipal solid waste (domestic, 
market and trade wastes); construction industry and demolition waste; fuel production 
and energy-generation waste; food, beverage and agro-industry waste; catering 
industry waste; forestry and forest product industry waste; amenity area and garden 
waste; slurries from intensive animal husbandry (animal manures); slaughterhouse 
solid waste (including specified materials) and diseased carcasses; waste sewage 
sludge (treated or untreated) and night soil; and septic hospital waste. These could 
further be categorized as : non-biodegradable inorganic matter; recalcitrant synthetic 
organic matter; biodegradable natural organic matter; off-specification and fire- and 
water-damaged chemicals of unknown composition and characteristics; toxic organic 
compounds; metals, metalloids and their derivatives;  and partially biodegradable 
natural organic matter. 
Taylor and Allen (2006) made a simple classification of waste into broad categories 
according to its origin and risk to human and environmental health, these are: 
household waste; municipal waste (MSW); commercial and non-hazardous industrial 
wastes; hazardous (toxic) industrial wastes; construction and demolition waste; health 
care wastes – waste generated in health care facilities (e.g. hospitals, medical research 
facilities); human and animal wastes; and incinerator wastes.  
 
1.4 Solid waste disposal patterns 
Disposal as defined in Florida Statutes 403.703 (2010) means the discharge, deposit, 
injection, dumping, spilling, leaking, or placing any solid waste or hazardous waste or 
any constituent thereof may enter other lands or be emitted into the air or discharged 
into any waters, including groundwaters or otherwise enter the environment.  
There are different methods of solid waste disposal; Hamer (2003) described simple 
methods of waste disposal which solid waste management industry finds its origin in 
as local terrestrial dumping (landfill), dumping into both fresh and marine waters and 
uncontrolled burning. 
According to Nelson (2007) solid waste disposal methods are:  
 
 
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Source Reduction – This involves the reduction of the amount of solid waste that is 
initially produced. This is meant to be the ideal solution, but so far, has been 
unsuccessful. According to USEPA (1999), source reduction is often called waste 
prevention and it is any change in the design, manufacturing, purchase or use of 
materials or products (including packaging) to reduce their amount of toxicity before 
they become municipal solid waste. 
Reducing waste volume.  
Pigs – Initially pigs were domesticated to consume peoples’ left overs and convert 
them into pork and bacon (Commons abundance network, 2015). In the United States, 
this method was a major source of reducing food wastes until in the 1960's when the 
practice was stopped because diseases were spread in this manner (Nelson, 2007). 
However, it was banned in European Union when there was an outbreak of Foot and 
Mouth disease in pigs in 2001 and it was thought that the outbreak of the disease was 
due to feeding of pigs with catering waste (Commons abundance network, 2015).    
In-sink garbage disposal - A garbage diposal unit is an electrically powered device 
that is installed under a kitchen sink between a sink’s drain and the trap 
(https://www.geapplianceparts.com/store/parts/category/disposers). It shreds food 
wastes into small pieces (generally less than 2 mm or 0.079 inches) to pass through a 
plumbing system (Shpiner, 1997). However, the method doesn't really reduce the 
volume of waste; rather, it transfers the waste into the sewer system (or into the septic 
tanks) (Nelson, 2007).  
Composting – The nature’s way of recycling is composting. It biodegrades organic 
wastes and turns them into valuable organic fertilizers (Ecochem, 2014). This method 
of recycling works very well to reduce the volume of organic wastes and the wastes 
can then be used in gardens, fields etc (Nelson, 2007).  
Recycling – This is a process of converting waste materials into new products to 
prevent wastes of potentially useful materials, reduction of consumption of fresh raw 
materials, reduction of energy usage, air pollution reduction (from incineration), 
reduction of water pollution (from landfilling) by reducing the need for conventional 
waste disposal and lower greenhouse gas emissions as compared to plastic production 
(Letsrecycle.com, 2006; The league of women voters, 1993).   
 
 
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Open dumps and sanitary landfills – Open dump is the improper disposal of any 
waste including household trash, garbage, tyres, barrels, demolition/construction 
waste, appliances, shingles, pipes, metal or any metal material which will rust, rot or 
burn (St. Clair County Health Department, 2014). Open dumps are often sited in 
wetlands, they are unlined and this makes them very unsafe, in terms of water 
contamination (Nelson, 2007).  
The uncontrolled disposal of municipal solid wastes (refuse) on land is sanitary 
landfilling. Sanitary landfills are covered up daily, to reduce vermin and smell 
(Nelson, 2007). Sanitary landfills are engineered disposal systems that are operated in 
accordance with environmental protection standards (USEPA, 1994). 
Incineration – The treatment for a wide range of wastes is incineration. In most 
waste treatments, the objective of waste incineration is to treat waste so as to reduce 
its volume and hazard, whilst capturing (and thus concentrating) or destroying 
potentially harmful substances (European Commisssion, 2006). The means to enable 
recovery of energy, mineral and/or chemical content from waste is also provided by 
incineration (European Commisssion, 2006). Incineration is beginning to play a much 
larger part in solid waste disposal and incinerated waste has a much smaller volume as 
ash, which is a lot easier (and safer) to dispose off (Nelson, 2007).  
Ocean dumping – This is the act of depositing all the waste materials from plastics, 
factories and industries, tankers and ships, and sewareage waste materials into the 
oceans and seas (Marine Insight News Network, 2016). This practice is no longer 
allowed; although at one time it was fairly popular (Nelson, 2007).  
Illegal Dumping – This is the deliberate act or unauthorized dumping, tipping or 
burying of waste on unlicensed or unfit land (EPA Victoria, 2012). It is a prolific 
disposal method, whether individually (tossing trash out of a window while driving 
down the highway) or on a large scale by industries (Nelson, 2007).  
Globally, there are different forms of disposal and management of solid wastes 
depending on the development of each country. For instance, according to 
Commonwealth of Australia (1996) urban areas of Australia and New Zealand have 
adequate sewerage systems and waste disposal services but in recent years they have 
come under strain especially in the largest cities. In the case of Sao Paulo in Brazil, 47 
 
 
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% of the garbage collected was disposed off in sanitary landfills, 32 % in controlled 
landfills and 30 % in open dumps (Gouveia and Ruscitto do Prado, 2010). 
In Western Europe, 66 % of municipal wastes went to landfills, 18 % was incinerated, 
9 % was recycled, 6 % was composted and 1 % was treated in other ways (OECD, 
1997). In some countries of West Asia, up to 50 % of waste generated is left 
uncollected; in their urban areas, disposal of waste is by open dumping and burning. 
In some Gulf Co-operation Council (GCC) countries, however, waste collection and 
sanitary landfills are highly efficient (Kanbour, 1997). 
In Latin America, 35 % of their wastes went to sanitary landfills while 25 % went to 
semi-uncontrolled landfills (PAHO, 1995). In North Africa, at least 20 % and as much 
as 80 % of urban solid wastes are disposed off by dumping in open spaces.    
Nigerian cities and towns are still facing waste handling disposal problems which are 
due to improper waste management. In Nigeria, dumping in open spaces is the most 
common form of waste disposal, uncontrolled burning and disposal in surface water 
bodies. There are some states that have pieces of land designated as legal or 
controlled dumpsites or sanitary landfills. Waste disposal in Ibadan involves direct 
dumping into water bodies, uncontrolled burning and disposal unto designated 
dumpsites or sanitary landfills. 
 
1.5 Solid waste contamination of soil, surface water and groundwater 
1.5.1 Soil 
Soil is a complex mixture of eroded rock, mineral nutrients, decaying organic matter, 
water, air, and billions of organic living organisms, most of them microscopic 
decomposers (Miller,1999). It is the major receiving medium of solid wastes. 
According to Marshal et al. (1996), the soil has traditionally been an important 
medium for organic waste disposal. The excessive input of unsorted municipal 
household wastes may likely lead to changes in soil physical and chemical 
characteristics and this can distort interrelationships among biophysical and chemical 
soil functions which may also lead to loading nitrates and heavy metals in soil and 
groundwater (Anikwe and Nwobodo, 2002).   
 
 
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Soil pollution also arises when wastes are being leached from landfills and the most 
common pollutants are metals such as mercury, cadmium, copper, lead, etc (Raman 
and Narayanan, 2008). 
 
The potential effects of soil pollution are as follows: 
1) Release of contaminants to the land surface, groundwater or surface water. 
2) Uptake of contaminants by plants. 
3) Direct contact by humans with contaminated soil. 
4) Inhalation of dust particles or volatile substances. 
5) Fire or explosion of landfill gases. 
6) Corrosion of underground pipelines and other building components. 
7) Generation of hazardous and secondary waste streams. 
8) Conflict with proposed land use. 
 
1.5.2 Surface water 
Water pollution is the undesirable change in physical, chemical and biological 
characteristics in the water bodies which may cause harmful effects on human and 
aquatic life (Tian et al., 2012). 
The function of the source quality, the nature of the physical, chemical and biological 
properties of contaminants and the re-aeration capacity of a system is the capacity of 
the surface water environment to assimilate contaminants and pollution (Olaniyan et 
al., 2009). 
Surface water is usually rain water that collects in surface water bodies, like oceans, 
lakes or streams, and also groundwater that discharges to the surface from springs 
(Surface Water Contamination Superfund USEPA. mht).  It may also be referred to as 
water on the surface of the planet such as in a stream, river, lake, wetland, or ocean 
(http://imnh.isu.edu/digitalatlas/hydr/concepts/surfhyd/srfwtr.htm). Sources of water 
pollution are generally grouped into two categories based on their origin. These are 
point sources and non-point sources.  
 
 
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According to section 502 (14) of the Clean Water Act (USEPA, 2012), the term 
"point source" means any discernible, confined and discrete conveyance, including 
but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, 
container, rolling stock, concentrated animal feeding operation, or vessel or other 
floating craft, from which pollutants are or may be discharged. This term does not 
include agricultural storm water discharges and return flows from irrigated 
agriculture. The point sources of pollution include municipal landfills, industrial 
waste disposal sites, leaking gasoline storage tanks, leaking septic tanks, accidental 
spills, leaks of petroleum products and of dense industrial organics. The non-point 
source is any source of water that does not meet the legal definition of point source 
(USEPA, 2012), this include atmospheric deposition, contaminated sediments, 
horticulture, agriculture (pesticides and fertilizers), logging, and onsite sewage 
disposal,  bacteria and nutrients from livestock, pet wastes and faulty septic systems, 
atmospheric deposition and hydromodification. 
When water passes through waste in a landfill cell, there is formation of leachate 
(landfill leachate.htm). It is as a result of fluids derived from rainfall; snowmelt and 
groundwater, together with liquids generated by the waste itself through processes of 
hydrolysis and solubilisation, brought about by a whole series of complex 
biochemical reactions during degradation of organic wastes, percolate through the 
deposit and mobilize other components within the waste (Taylor and Allen, 2006). 
According to Ozanne (1990), leachate corresponds to atmospheric water that has 
percolated through waste, interacting with bacteriological activity and especially 
organic substances. It has the ability to pollute either groundwater or surface water 
since it might percolate through the soil or direct infiltration on site (Leachate. 
www.foe.org/site1/ptp/chapter 3.html).   
 
1.5.3 Groundwater  
Surface water seeps through the soil and becomes groundwater; so also groundwater 
can also feed surface water sources. Groundwater is water that occupies the pores or 
crevices of soil or rock (Water or Rivers Commission, 1998). These include wells and 
boreholes. 
One of the potential causes of groundwater contamination is land disposal of 
municipal solid waste.  Soluble components of solid waste in contact with water will 
 
 
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change the groundwater quality either directly or indirectly by infiltration of 
contaminated surface water (Golwer and Matthess, 1968). According to Noring 
(1951) and Legrand (1965), the extent and intensity of contamination of groundwater 
depends on the factors listed below: 
a) The waste materials’ chemical and physical qualities 
b) The variable pattern of waste disposal by man and the accidental release of 
contaminants in the ground. 
c)  Duration and surface size of contact between waste material and water in the 
saturated and unsaturated zones of the ground varying in time. 
d) The contaminants’ behavior in the surface water and in the saturated and 
unsaturated zone of the ground. 
e) The physical and chemical properties of soil and rock environment varying 
within space. 
f) Microorganisms’ influence in saturated and unsaturated zone varying in time. 
g) The qualities of water percolating from surface water or from other aquifers 
into an aquifer of specific character varying in time. 
h) Climatic conditions varying in time. 
i) Hydrologic conditions varying in time and space. 
j) Man’s pattern of water development from wells. 
The soil is linked to groundwater pollution in various ways: 
1) When a chemical comes into contact with soil moisture, the chemical has the 
characteristics of solubility, adsorption, volatility, and degradation. 
2) The texture, permeability and organic matter content of the soil are the 
important characteristics of the soil which help determine groundwater 
contamination. 
3) The depth to groundwater at a specific location is also important because the 
soil between the surface and groundwater acts as a filter. Less soil means more 
leaching, less adsorption, less degradation. 
4) Cold soils due to the climatic condition slow the rate of degradation and 
increase the time a chemical is available for leaching. 
 
 
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The linkage of soil to groundwater pollution was supported by Critto et al. (2003). 
They observed a migration of hydrophilic organic compounds, which was identified 
cumulatively by dissolved organic carbon (DOC) from the soil to the surface and 
semi–confined aquifers. The evidence of the migration was supported by behavior of 
anions sulphate and chloride, which also underwent transfer from surface soils to 
underlying aquifer. Also highest concentration of chloride leachated from the urban 
solid waste discharged into the landfill was found within the semi–confined aquifer 
while highest concentration of sulphate and dissolved organic carbon were in the 
surface aquifer. 
 
1.6 Impacts of solid waste and leachate on organisms 
Leachate has an origin other than domestic or commercial waste. For example, 
leachate from a chemical waste site can have an effect that is totally different, there 
may not be any changes in the physical appearance of the water but it may cause 
sterility in the water (Henton, 1982). Studies by Henton (1982) revealed that in 
Scotland, leachate polluted surface water bodies with biochemical oxygen demand 
(BOD) and ammonia as the chief pollutants. The BOD deoxygenated the water and 
resulted in “thick growths of sewage fungus” on the bed of the water course. 
Ammonia was highly toxic to fish life and caused instantaneous fish-kills when it first 
entered the water. High chlorides and heavy metals were also present. This thus 
affected activities such as fishing, stockwatering and land drainage but 
overwhelmingly the destruction of the amenity value of the water course was the most 
serious effect. Further studies by Alkassasbeh et al. (2009) on the toxicity of leachate 
from three landfills in Malaysia, revealed that at the different leachate concentrations, 
the Common Carp (Cyprinus carpio) showed behavioural changes, decline in general 
activity, loss of balance, breathing difficulties, excessive mucosal secretion and 
gathering at the surface for breathing.  
Further investigation on leachate toxicity showed that rats exposed to raw and 
simulated leachates of different concentrations showed chromosome aberrations in a 
concentration dependent manner (Alimba et al., 2006).  
Indiscriminate dumping of refuse also permits the breeding of different organisms, 
like flies and rodents that can transmit various diseases to man. 
 
 
 
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1.7 Ibadan city 
Ibadan city in Nigeria is one of the largest in sub-Saharan Africa. There are huge 
quantities of waste production and improper methods of disposal of wastes in Ibadan, 
which is causing environmental pollution. Aesthetic values of some areas have also 
been negatively affected. This city is seriously experiencing problem of municipal 
waste management, principally as a result of unplanned development, rural-urban 
migration and natural increase within the city (Akinbiyi, 1992). 
Inhabitants of the core areas of Ibadan majorly deposit their wastes and defaecate 
directly into streams flowing around them. Along the highways of Ibadan, heaps of 
wastes are found there; if not recently that the present government has now intensified 
effort by clearing the refuse. There are some streets (Ojokondo) within the city where 
there are heaps of wastes that even reach the height of a-storey building. However, in 
some areas where the high-class people inhabit, there are refuse drums placed in front 
of various houses for wastes and the workers of the state’s waste management board 
move the wastes to the legal dumpsites within the city. 
 
1.8      Justification 
Ibadan city is still facing waste handling disposal problems which are due to improper 
waste management. Most of the core areas within the city experience indiscriminate 
dumping of refuse into water bodies and land. This affects qualities of soil, streams 
and groundwater around such waste sites. This also affects the existence or abundance 
of certain fauna inhabiting such areas.  
Earthworms are the dominant fauna in most soils, therefore, there is need to check 
their abundance in soil from stream banks and dumpsites.  
There is also a need to assess the ecotoxicological effects of the waste by using some 
animals as test models. Therefore, the use of: 
 Earthworms - Eudrilus euginiae (Kinberg, 1867), 
 Aquatic insects - larvae of mayflies, Cloeon perkinsi (Barnard, 1932), 
 Amphibians tadpoles - Rana temporaria (Linnaeus, 1758) and 
 Frys and fingerlings of Clarias gariepinus (Burchel, 1822).  
 
 
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The soil is a sink for contaminant, so there is need to check the top soil (0 -15 cm) 
qualities. 
The streams receive most of the wastes; they serve as sources for larger bodies such 
as dams or reservoirs. There is need to investigate the effects of the refuse dump on 
their physico-chemical qualities.  
The groundwater qualities also need to be investigated since most of the population 
depends on them for drinking. 
 
1.9 Aim of the study 
The aim of this study was to investigate the physico-chemical qualities of soil, 
streams and groundwater (wells), abundance and diversity of earthworms; and acute 
toxicity of solid waste-contaminated water on some fauna associated with dumpsites 
in ten local government areas of Ibadan. 
 
1.10    Objectives  
The study had the following objectives: 
 Determination of the impact of solid waste on top soil qualities. 
 Determination of the impact of solid waste on soil from banks of streams 
receiving the wastes. 
 Assessment of the physico-chemical analysis of the streams that receive 
wastes.  
 Assessment of the physico-chemical analysis of the groundwater close to the 
different waste sites. 
 Ascertain the negative impacts of the waste disposal patterns on the local 
community. 
 Identification of the different species of earthworms found in the soil 
of the dumpsites. 
 Determination of the acute toxicity of the solid waste in five taxonomic 
groups: 
Annelids (Eudrilus euginiae) 
Arthropods (Insecta – Cloeon perkinsi) 
Amphibian (Rana temporaria) 
Fish (Clarias gariepinus)  
 
 
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CHAPTER TWO 
LITERATURE REVIEW 
2.1 Solid waste: Definition and generation 
Solid waste as defined by Olexa et al. (2003) includes garbage, refuse, yard trash, 
clean debris, white goods, special waste, ashes, residuals (sludge), solid, or semi-solid 
material, or contained gaseous material. The definition specifically includes 
agricultural, commercial, domestic, governmental, and mining wastes. The definition 
specifically excludes pollution. 
Solid wastes are generated by almost every activity and the amount varies by source, 
season, geography and time (Robert, 1999). The by-product of urbanization is solid 
waste (Tahir et  al., 2015). According to Hoornweg and Bhada-Tata (2012), municipal 
solid waste which is one of the most important by-products of an urban lifestyle is 
growing faster than the rates of urbanization. Their report estimated that in 1992, 2.9 
billion urban residents generated about 0.64 kg of municipal solid waste per day (0.68 
billion tonnes per year) which has increased to about 3 billion residents generating 1.2 
kg per person per day (1.3 billion tones per year) in 2013 and by 2025, about 1.42 
kg/capital/day (2.2 billion tones per year) of municipal solid waste will be generated 
by 4.3 billion urban residents. By 2025, globally solid waste management costs will 
increase from today’s annual $ 205.4 billion to about $ 375.5 billion and cost 
increases will be most severe in low income countries (more than five-fold increases) 
and lower-middle income countries (more than four-fold) (Hoornweg and Bhada - 
Tata, 2012). 
In the United States, 158 million tonnes of municipal solid wastes are produced 
annually (Olafusi, 2004), it increased to 254 million tonnes in 2013 (USEPA, 2013), 
while it was estimated in 2014 that 1.99 kg of municipal solid waste was generated 
per person per day (USEPA, 2014). 
 
 
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In Nigeria, 25 million tonnes of municipal solid wastes are generated annually and the 
waste generation rates ranged from 0.66 kg per capital per day in urban areas to 0.44 
kg per capital per day in rural areas (Ogwueleka, 2009). Olafusi (2004) reported that 
estimate of 44 pounds (20 kg) of municipal solid waste was generated per capita per 
year while Babayemi and Dauda (2009) reported 0.58 kg per person per day. In 
Lagos, 9 000 to 10 000 metric tonnes of wastes were produced per day (Olubori, 
2011) while the rate of solid waste generation per person was 0.3 kg per capita per 
day (Habitat, 1997). Ibadan has 1.1 kg per capita solid waste generation per person 
per day (Habitat, 1997). 
Solid waste generation rate of some cities in Nigeria was reviewed by the Federal 
Ministry of Housing and Environment (FHME, 1982), Lagos generated 55,991 tonnes 
per year; Ibadan, 55, 224; Port Harcourt, 51, 390; Aba, 54, 458; Kano, 39, 885 while 
Jos, 18, 792. Another review by the Enugu State Environmental Sanitation (1994), 
reported that there was tremendous increase with Ibadan having 733, 542 tonnes, Port 
Harcourt had 285, 466, Aba had 113, 300, Enugu 78 603, Abeokuta 73, 386, Kano 72, 
066, Jos 33, 977 and Benin had 32, 327 (Ezeji, 2010). A review carried out in 2007 
also showed a significant monthly increase with Lagos generating 255, 556 tonnes 
with 0.63 kg per capital per day; Kano, 156, 676 tonnes with 0.56 kg per capital per 
day; Ibadan; 135, 391 tonnes with 0.51 kg per capital per day; Port Harcourt, 117 825 
tonnes with 0.60 kg per capital per day; Makurdi, 24, 242 tonnes with 0.48 kg per 
capital per day; Onitsha, 84, 137 tonnes with 0.53 kg per capital per day; Nsukka, 12, 
000 with 0.44 kg per capital per day; and Abuja, 14, 785 tonnes with 0.66 kg per 
capital per day (Ogwueleka, 2009).  According to Iruruaga (2012), the rate of waste 
generation in Lagos state was 9, 000 tonnes per day while in Kano it was 3, 849 
tonnes per day and generally, the average rate was 0.5 kg/capital/day. 
 
2.2 Refuse storage 
There are different ways of storing household refuse. These include the following: 
A container of capacity 100-200 litres, preferably plastic or metal and with a tight- 
fitting lid should be provided for 10-20 families not more than 15 m from the shelter 
(United Nations High Commissioner for Refugees, 1999). 
One container of 50-100 litres may be provided for every 25-50 people (Pan 
American Health Organization, 1996). 
 
 
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Large street-corner storage containers, with tight-fitting lids.  
All the above allow two days worth of refuse to be stored. 
Large containers or collection bays to be used in markets and commercial areas. 
 
2.3 Treatment and movement of household refuse and market wastes 
1) Burial 
a) Small refuse pits in low-density settlements, where relatively small quantities of 
refuse are produced. 
b) Communal trench 1.5 metres wide and 2 metres can be excavated by hand for 
refuse. 
2) Sanitary landfill 
The landfill site should be 
a) Located away from the settlement; 
b) Accessible; 
c) On vacant or uncultivated land; 
d) Located in natural depressions with slight slopes; 
e) Downwind from the settlement; 
f) Sited and organized to avoid surface water and groundwater pollution; 
g) In an area that is not exposed to landslides or earthquakes. 
It has been estimated by World Health Organization, United Nations Environmental 
2
Programme (1991) that an area of 0.4 – 0.5 hectares (4000m – 5000 m ) can serve 10, 
000 inhabitants. 
3) Incineration 
4) Waste recycling 
 
2.4 Earthworms, environmental factors and contamination 
Earthworms are one of the dominant fauna in soil. They are often grouped according 
to their physical appearance (body color, shape and size) and ecological functions 
such as burrowing abilities and food preferences (Bouché, 1977). This makes 
 
 
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researchers to ecologically group them as epigeic, anecic and endogeic earthworms. 
Epigeic earthworms are small earthworms that live in the upper litter layer of the soil, 
typically ingest litter and humus without extensively mixing organic and inorganic 
materials (Lavelle, 1988). Anecics are large deep burrowers that come to surface 
when it is time to feed whereas endogeics live near the surface of soils in the organic 
horizons while producing horizontal galleries (Paoletti, 1999). Endogeics are found in 
the first 10 to 20 cm and anecics in the deeper recesses of the soil (Mainoo, 2007). 
The combinations of these ecological categories, together or individually are 
responsible for maintaining the fertility of soils in the majority of habitats (Bhadauria 
et al., 1997). 
Environmental conditions critically affect cocoon production, rates of development, 
and growth of earthworms (Dominguez and Edwards, 2011). So also, earthworm 
communities are influenced by a suite of hierarchial factors with temperature 
dominating, followed by edaphic (nutrient status) and environmental (seasonality) 
factors (Fragoso and Lavelle, 1992). According to Chauhan (2014), soil factors that 
regulate earthworm population include organic matter, total nitrogen, available 
phosphorus, texture and pH. Earthworms have fairly complex responses to changes in 
temperature (Dominguez and Edwards, 2011). The unfavorable effect of high 
temperatures (above 30°C (86°F)) on most species of earthworms is not entirely a 
direct effect because these warm temperatures also promote chemical and microbial 
activities in the substrate, and the increased microbial activity tends to consume the 
available oxygen, with negative effects on the survival of earthworms (Dominguez 
and Edwards, 2011). The moisture content of organic wastes and the growth rate of 
earthworms have strong relationships (Dominguez and Edwards, 2011). The pH range 
that is suitable for earthworms’ growth is about 4.2 to 8.0 (Sherman, 2003). Most 
epigeic earthworms can tolerate pH levels of 5–9, but when given a choice in the pH 
gradient, they move toward the more acidic material, with a pH preference of 5.0; 
They are very sensitive to anaerobic conditions since they lack specialized respiratory 
organs, and oxygen and carbon dioxide diffuse through their body wall; They are very 
sensitive to ammonia and cannot survive in organic wastes containing high levels of 
this cation, they also die in wastes with large quantities of inorganic salts (Dominguez 
and Edwards, 2011).  
 
 
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Earthworms enrich and improve the soil or plants, animals and also humans. They 
aerate the soil layers and feed on organic matter. The mixing of the soil and organic 
matter made Charles Darwin (1881) to refer to them as nature’s plough (Earthworm 
Society of Britain, 2014). They are the best known and often the most important 
animals influencing the functioning of soil ecosystems (Hendrix and Bohlen, 2002). 
They significantly influence soil structure, nutrient cycling and crop productivity 
(Gonzalez et al., 2006). They often dominate the fauna of soil food webs in terms of 
biomass (Lee, 1985; Lavelle et al., 1999) and their casting and burrowing activities 
increase soil porosity, stimulate microbial activities, and accelerate litter decay and 
the release of nutrients into the soil (Lee, 1985; Lavelle et al., 1999; Gonzalez and 
Seastedt, 2001; Gonzalez, 2002; Liu and Zou, 2002). The abundance and species 
composition of earthworms fauna at a particular site and also the preference, 
avoidance or activity of individual earthworms (that is, the behavior) in contact with a 
soil substrate, can indicate the quality of the soil (Heinz-Christian et al., 2011). 
Anthropogenic activities generally spread populations of exotic earthworms therefore 
leading to a dominance of exotic species in agricultural soils (Lee, 1985). 
 
2.5 Impacts of solid waste on soil 
The soil is the major receiving medium of solid wastes. According to Marshal et al. 
(1996), the soil has traditionally been an important medium for organic waste 
disposal. The excessive input of unsorted municipal household wastes may likely lead 
to changes in soil physical and chemical characteristics and this can distort 
interrelationships among biophysical and chemical soil functions which may also lead 
to loading nitrates and heavy metals in soil and groundwater (Anikwe and Nwobodo, 
2002).   
Soils differ in their response to organic waste amendments and it is important to 
investigate more closely the influence of these organic and inorganic wastes on a 
range of soil physico-chemical properties (Mbagwu, 1989). There could be changes in 
soil physical properties when humic acid, which is an exogeneous substance in 
municipal wastes react with soil components (the hydrophilic groups in the humic 
acid can interact with the polyvalent cations present on the surface of soil particles) to 
cause changes in soil physical properties (Piccolo and Mbagwu, 1997).  
 
 
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Soil organic matter is a reservoir of essential and non-essential mineral elements for 
plant growth and development; hence increased organic matter may lead to increased 
soil productivity (Anikwe and Nwobodo, 2002). It can reduce bulk density and 
increase total porosity and hydraulic conductivity in heavy clay soils (Anikwe, 2000) 
and influences the degree of aggregation and aggregate stability (Mbagwu and 
Piccolo, 1990). High levels of organic matter were observed in municipal solid waste 
dumpsites in Uyo municipality, Nigeria (John et al., 2006; Anikwe and Nwobodo, 
2002). Okeke (2014) also observed high organic matter contents of topsoil and subsoil 
of ferrealsol soil receiving solid waste in Owerri, Nigeria. Soil samples collected from 
a dump-field in Yenagoa, Bayelse state, Nigeria also had high levels of organic matter 
(Amos-Tautua et al., 2014). In addition, waste-amended soils have also been reported 
to have high organic matter content (Anikwe, 2000).  An increase in soil pH of waste 
dumpsites in urban Abakaliki, Southeastern Nigeria was observed by Anikwe and 
Nwobodo (2002). Ideriah et al. (2006) also observed increase in pH of a dumpsite in 
Port Harcourt, Nigeria. In the analysis of soils from waste dumpsites in Benin, 
Nigeria, Oviasogie and Oviasogie (2014) also obtained an increase in the soil pH. 
This may be due to high organic matter content which tends to buffer the soil by 
preventing excessive pH changes due to exchangeable cations during mineralization 
of organic matter (Woomer et al., 1994). Increased pH in dumpsite soils is a positive 
productivity indicator in an acidic tropical soil where low pH limits uptake of nutrient 
elements.  
John et al. (2006) observed high nitrogen content in municipal dumpsites in Uyo. 
High nitrogen content was also observed by Oviasogie and Oviasogie (2014) in waste 
dumpsites in Benin. This was also observed in soils from a municipal dumpsite in 
Abakaliki by Anikwe and Nwobodo (2002) which they reported that this may be due 
to the high amount of vegetation observed at their dumpsites. 
High cation exchange capacity (CEC) which increased down the profile by 7 – 25%, 
and also higher percent base saturation which was as a result of increased sodium, 
potassium, calcium, and magnesium were observed by Anikwe and Nwobodo (2002) 
in soils from a municipal dumpsite in Abakaliki. 
Critto et al. (2003) observed high concentrations of sulphate and chloride in soils of 
an illegal landfill in Venice, Italy. The high concentrations were likely to be derived 
from the rainfall leaching processes that dissolve the large quantities of the chalks and 
 
 
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transport the liquors percolated from urban solid waste discharged into the landfill. 
Waters percolated from urban solid waste landfill normally contain high chloride 
levels, commonly in 2 000 – 3 000 mg/L average range (Cecchi et al., 1993). 
Continuous disposal of municipal wastes in soil may increase heavy metal 
concentration and this may consequently have harmful effects on soil, plants and 
human health. Environmental contamination and exposure to heavy metals, is a 
serious growing problem throughout the world because metals are non-biodegradable 
and persistent in the ecosystem; physical, chemical and biological processes may 
combine under certain conditions to concentrate metals rather than dilute them: and 
the societal impact of a contaminated system is substantial. 
In uncontaminated soil, the typical metal recommended are Zinc 80 mg/kg, copper 20 
mg/kg, nickel 25 mg/kg and cadmium 0.5 mg/kg (DOE/NWC, 1981). Lead is the 
most widespread source of contamination of soils and plants (Wild, 1973). It stays a 
long time in both soil and water (Tuberose.com, 2005). Because lead is immobilized 
by the organic components of soil, most of it deposited from air is generally retained 
in the upper 2 – 5 cm of undisturbed soil (EPA, 1986; NSF, 1977). According to 
Kabata-Pendias and Pendias (1984), the normal range of lead in soils is from 2 to 300 
-1
mg Kg . Oketola and Akpotu (2014) observed high contents of heavy metals (Zn, Pb, 
Cr, Cu and Cd) in topsoils of some dumpsites in Lagos and Ibadan. Anikwe and 
Nwobodo (2002) observed increased levels of heavy metals (Pb, Cu, Fe and Zn) in 
soils of the municipal waste sites in Uyo.   They observed lead content of Waterleaf 
-1
(Talinum triangulare) leaves to be 83.92 mg Kg  which is within critical 
-1
concentration of 30 to 300 mg Kg  reported by Kabata-Pendias and Pendias (1984). 
This is contradictory to what Amusan et al. (1999) found out in Waterleaf (Talinum 
triangulare) and Okra (Abelmuscus esculentus) grown in a dumpsite at Obafemi 
Awolowo University garbage dump. They observed that lead uptake of Waterleaf 
increased by 2003 % and 733 % in leaves and roots respectively and 126 % in roots of 
Okra relative to those grown in non-dumpsite.  However, Miller and Miller (2000) 
postulated that lead is not taken up by plants to any degree, and thus plants are not a 
major risk pathway for ingesting lead.  
Trace elements accumulation in soil in dumpsite may lead to increased uptake of trace 
elements in plants although their transfer ratios differ from crop to crop (Anikwe and 
Nwobodo, 2002).  This may mean that as the level of these metals in the soil is 
 
 
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significantly increased, some test crops have the potential of showing increased 
uptake of metals (Amusan et al., 1999). Voutsa et al. (1996) maintain that there is 
generally not a strong relationship between the concentrations of heavy metals in soil 
and plants, because it depends on many factors such as soil metal bioavailability, 
plant growth, and metal distribution to plants. 
Anikwe and Nwobodo (2002) observed normal range of copper in soil (2 – 250 mg 
-1
Kg  as reported by Kabata-Pendias and Pendias (1984)). However, Amusan et al. 
(1999) found that leaves of Waterleaf plants grown in dump soil contained 29.20 mg 
-1
Kg   Cu which was well within the critical range found in plant tissues (20 – 100 mg 
-1
Kg ). They also obtained zinc values which were within the normal range obtained in 
-1
soil (10 – 300 mg Kg , Logan, 2000). Miller and Miller (2000) noted that zinc and 
copper are toxic to plants before they accumulate in sufficient tissue concentrations to 
affect animals or humans. As a result, over application tends to kill or stunt plants, 
minimizing opportunities for poisoning animals and humans consuming them 
(Anikwe and Nwobodo, 2002). 
 
2.6 Impacts of municipal solid wastes and leachate on terrestrial organisms 
Since the soil is the major receiving medium of solid wastes, therefore the organisms 
(minute microorganisms to human beings) found on land are exposed to various 
effects of solid wastes and leachates. 
Simonsen and Scott-Fordsmand (2004) found significant correlation of copper and 
zinc in earthworms with the total concentration and CaCl2 extractable fraction of the 
metal in the soil. Canbek et al. (2005) found the mean lead concentrations of 
earthworms to be lower than those of the mean soil samples. This conformed to the 
work of Bamgbose et al. (2000); they reported lower levels of lead in earthworms 
from dumpsites in Abeokuta, Nigeria. Nahmani et al. (2004) observed that metal 
pollution reduced species richness of earthworms (from 6 to 1 species). Morgan and 
Morgan (1988) in their research on two ecophysiologically dissimilar earthworm 
species, found tissue lead concentration of earthworms to be substantially lower than 
the total soil lead concentrations but at a particular site, the tissue lead concentration 
were approximately 5 to 10 times higher than that of the soil. High heavy metals (Pb, 
Cd, Ni, Cr, As, Mn, Hg) concentrations were also observed by Uzoije et al. (2013) in 
their analysis of heavy metals present in earthworms collected from waste-polluted 
 
 
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soils of Nnewi, Nigeria. Udousoro et al. (2015) observed high accumulation of lead 
(Pb), cadmium (Cd) and iron (Fe) in Eudrilus euginiae earthworms collected from 
toxic metals impacted soils in Akwa Ibom, Nigeria. 
Rats exposed to raw and simulated leachates of different concentrations were 
observed and they showed chromosome aberrations in a concentration-dependent 
manner (Alimba et al., 2006). Leachate-induced genotoxicity were found in mouse 
(Tewari et al., 2005; Sang and Li, 2005; Bakare et al., 2005), Drosophila 
melanogaster (Siddique et al., 2005) and Allium cepa (Cabrera and Rodriguez, 1999; 
Bakare and Wale-Adeyemo, 2004; Sang and Li, 2004). Alimba et al. (2012) observed 
histopathological lesions in the liver and kidney of wistar albino rats exposed to 
leachates from Olusosun and Aba Eku landills in Ibadan, Nigeria. Alimba and Bakare 
(2016) also observed significant increase in micronucleated normochromatic 
erythrocytes formation in the bone marrow of rats exposed to landfill leachates from 
Aba Eku, Ibadan.  
Microorganisms enter the human body through hand-to-mouth contact during eating, 
drinking, and smoking, or by wiping the face with contaminated hands or by licking 
splashes from the skin (SEPA, 2007). Improper disposal of human faeces transmit a 
number of major diseases, which include diarrhoea, schistosomiasis, hepatitis A and 
E, dysentery, cholera, typhoid fever, and also infection with helminthes and trachoma. 
Improper disposal of solid wastes are also associated with vector-borne diseases such 
as malaria and dengue fever (http://www.emro.who.int/CEHA/pdf/Pakistan.pdf).  
Nitrate causes metheglobinemia, or blue baby syndrome, a condition that prevents the 
normal uptake of oxygen in the blood of young babies (National Small Flows, 
Clearinghouse, 2007).  
Fecal coliforms do not pose a health threat but serve as an indicator for bacteria that 
can cause illness in humans and aquatic life (Caldwell, 2007). However, if they are in 
high concentrations, they are a problem to human drinking water. 
When wastes that are not properly disposed contaminate drinking water, diseases may 
result which may finally lead to death. The disease may be diarrhea especially in 
children, with major enteric pathogens which include rotavirus, Camplobacter jujeni, 
enterotoxigenic Escherichia coli, Shigella spp. and Vibrio cholerae 01, and possibly 
enteropathogenic E. coli, Aeromonas spp. V. cholera 0139, enterotoxigenic 
 
 
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Bacteroides fragilis, Clostridium difficile, and Crytosporidium parvum. In adults, in 
addition to traditional pathogens (helminthes, Entamoeba histolytica, Giardia lamblia 
hepatitis A and E), enterovirus, C. jujen and Helicobacter pylori are emerging issues 
(Ashbolt, 2004). 
Alkaline Comet assay was used to observe human peripheral blood lymphocytes 
exposed to leachates and solid wastes from a polyfiber factory, an aeronautical plant, 
and a municipal sludge leachate. The result showed that there were DNA damages in 
the lymphocytes (Bakare et al., 2006).     
Onyidoh (2006) reported that most developing cities due to poor waste disposal are 
infested with arthropods, rodents, mollusks or alternative hosts of human disease, 
sleek, fat and rats which expose people to rat bite fever, murine typhus, bubonic 
plague and other diseases. Furthermore, some outbreaks of bubonic plague, secondary 
cases of plague pneumonia are seen. 
A famous episode of Minamata disease occurred in Japan in the fifties due to 
consumption of fish contaminated by methyl mercury (Central Pollution Control 
Board, 2006). Sharma (2002) reported that in Shimla, India, waste indiscriminately 
thrown into nullahs and on the roadside contaminated the water supply and stomach 
ailment increased in the town. Cancer risk analysis conducted in United States 
indicated that 60 % of municipal solid wastes landfills posed a cancer risk of less than 
one in 10 billion, another 6 % posed a risk of less than one in a million (Chilton and 
Chilton, 1992).  
 
2.7 Mayflies and contamination 
Mayflies are aquatic insects belonging to the order Ephemeroptera. Ephemeropterans 
are sensitive indicators of water qualities (Pontasch and Cairns, 1988; Short et al., 
1991; Williams and Williams, 1998) particularly to contaminants such as metals and 
ammonia (Peckarsky and Cook, 1981) and they have been regarded as the most 
sensitive order of aquatic invertebrates (Echols et al., 2010). 
Mayflies’ nymphs are important components of freshwater ecosystems 
(www.science.jrank.org/pages/4188/Mayflies-Ecological-economic-importance-
mayflies.html). They live for a very long time in the bottom of water in U-shaped 
burrows that they construct. There have been significant effects on mayflies diversity 
 
 
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throughout the world due to impact of human activities (Landa and Soldan, 1995). 
The presence of mayflies in an aquatic ecosystem is a strong indication that the water 
quality conditions are good and a healthy water body (Krieger, 1997; Voshell and 
Reese, 2002). They are specific in their choice of habitat requirements and tolerance 
of environmental conditions such as water temperature and chemistry (Krieger, 1997). 
They also play an important role in the food web because they acquire energy from 
decomposed plant material, move it to higher consumers like macroinvertebrates, fish, 
birds, etc. More mayflies result in more fish (Krieger, 1997).  
Mayflies’ nymphs are very sensitive to pollutants in the water and the sediments 
because of their constant contact with the sediments where the pollutants accumulate. 
If there is high concentration of pollutants, the mayflies could die or their 
development could be altered. If the sediments and the water qualities are good, they 
complete their life cycle. There was mass death of nymphs of mayflies Hexaginia 
rigida and Hexaginia limbata in Lake Erie during the 1950s and early 1960s, due to 
its pollution by organic debris associated with sewage and algal growth which used up 
oxygen in the bottom of the lake (Krieger, 1997).  
Exposure to sublethal concentration of metals reduces growth, fecundity and survival 
of aquatic organisms. Mayflies are sensitive indicators of metal pollution. Their 
abundance and species richness were biological indices to detecting impacts of metal 
pollution in Rocky Mountain stream in Colorado (Kiffney and Clements, 1994; 
Kiffney and Clements, 1996; Clements et al., 2000). Lower abundance of mayflies, 
especially heptageniid mayflies was observed by Clements et al. (2000) in their 
survey of 95 sites in the southern Rocky Mountain ecoregion in Colorado.  
Mayflies are sensitive to acidification, show reduced densities and/or richness at low-
pH sites, which is as a result of acidic deposition through precipitation (that is, acid 
rain) (Thorp and Rogers, 2014).   
One of the most common and diversified genera is the genus Cloeon Leach, 1815 
Ephemoreptera (Salles et al., 2014). Cloeon perkinsi is the most abundant of the 
African Cloeon with nymphs occurring in many types of still or slowly moving water 
from temporary ponds to the margin of large lakes (Gillies, 1980). However, Cloeon 
dipterum larvae (a species found in the temperate zones) support water of low quality, 
that is α-β mesosaprobic (Zelinka and Marvan, 1961) and temporary anoxia (Nagell, 
1977). Four saprobic zones according to biochemical oxygen demand (BOD) were 
 
 
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divided. They are oligosaprobic – 1 - 2.5 mg/L and β mesosaprobic (2.5 – 5 mg/L), α- 
mesosaprobic (5 – 10) and polysaprobic (10 - 50 mg/L) (Curds, 1992). 
 
2.8 Tadpoles and contamination 
Amphibians are bioindicators of environmental stress (Hall and Mulhern, 1984; 
Freda, 1991; Dunson et al., 1992), especially due to decline of some population 
(Barinaga, 1990). Amphibians are very important components of different ecosystems 
worldwide. The deposition of their unshelled eggs in aquatic environment, 
development into a gill-respiring, swimming herbivorous/detritivorous larval stage 
and an adult stage which is semi-aquatic climbing/hopping insectivorous make them 
highly vulnerable to numerous stressors in both aquatic and terrestrial environment 
(Wassersaug, 1997). They are highly sensitive to many pollutants such as aluminium, 
cadmium, iron, lead and zinc and pesticides such as atrazine and DDT (Gupta, 2009). 
They can take up toxicants by both dietary ingestion and dermal absorption, this 
makes them to potentially accumulate significant body burdens (Gupta, 2009). Their 
highly permeable skin that is involved in dermal respiration also facilitates potential 
uptake of contaminants. 
Tadpoles growth and survival can be affected by alterations in environmental factors 
such as limitation of resources, predation, crowding and dessication of habitat (Shi, 
2000). If these factors are present, they either stimulate growth during 
prometamorphosis or inhibit it during premetamorphosis (Shi, 2000). 
Anuran amphibians are susceptible to the uptake of heavy metals due to their highly 
permeable skin that allows the rapid absorption of metal ions (Ficken and Byrne, 
2003). Tadpoles frequently ingest sediments that have accumulated heavy metals; this 
is due to the microphagous feeding habit of most species (Hopkins and Rowe, 2010). 
Ecological relevant concentrations of metals are lethal to amphibian embryos, larvae 
and adults (Linder and Grillitsch, 2000; Hopkins and Rowe, 2010). Sublethal 
concentrations can have harmful effects on tadpoles, which include reduced growth 
rates, delayed metamorphosis and impaired behavioural responses (Hopkins et al., 
2000; Hopkins and Rowe, 2010). 
Ficken and Byrne (2003) observed that the concentrations of copper, nickel, lead, 
zinc, cadmium and mercury in water of Merri Creek Corridor in Victoria, south-
 
 
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eastern Australia significantly affected anuran species richness. It was also negatively 
affected by orthophosphate and conductivity of the water. 
Juveniles of anurans accumulated greater concentrations of polychlorinated biphenyls 
(PCBs) compared to adults collected from the same contaminated stream locations 
flowing from Paducah gaseous diffusion plank, Paducah, Kentucky (De Garaday and 
Halbrook, 2006). 
 
2.9 Fish and contamination 
Fish is very high in protein, which makes it very important in the human diet to help 
for body growth and maintenance of muscle tissues. About 25 % of animal protein is 
from fish and shellfish, about 35 % of all fish is eaten fresh, frozen or chilled, 16 % 
each is cured or canned, while 32 % is made into oil and fish meal (Ayoola, 2010). In 
Nigeria, the local production of fish is 0.51 million tonnes, while the national demand 
for fish is about 1.85 million tonnes based on population figure of 140 million people, 
therefore, to meet the growing demand, tilapia and catfish are being produced by 
domestic fish farmers (Ayoola, 2010). 
Clarias gariepinus is a major fish species for aquaculture in Africa (Sotolu, 2010). It 
has omnivorous feeding habit, high growth rate, and resistance to handling and stress 
(Fagbenro and Davies, 2001). Naturally, it is found in fresh water bodies such as 
streams, rivers, floodplains, swamps and lakes. A mature female lays about 60, 000 
eggs. 
Clarias gariepinus is of commercial importance in aquaculture due to its positive 
attributes like resistance to diseases, high fecundity and ease of larval production 
(Hogendoorn, 1980; Haylor, 1991; Kestemont et al., 2007). However, in the larval 
stages of catfish, there is high mortality attributed to infectious diseases caused by 
parasites. Reproduction in the African catfish is in response to environmental stimuli 
such as a rise in water level and inundation of low-lying areas (FAO, 2015). 
Fishes are a key unit in many natural aquatic food webs and they can also serve as 
environmental indicators of polluted water (APHA, AWWA, WEF, 1998). 
Temperature, dissolved oxygen, pH, salinity and water movement are often the 
dominant factors that affect fish distribution in the aquatic environment (Boyd, 1982). 
Nevertheless, temperature has effect on the rate of metabolism and consequently on 
 
 
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the rates of feeding, growth and reproductive activities (Crillet and Quetin, 2006). In 
Lake Victoria, the young of two groups of Cichlids sorted themselves out in shallow 
water on hot days according to their ability to tolerate high temperature; tilapiine 
Cichlids were found in the hottest shallowest water, while haplochromine Cichlids 
were found in slightly cooler and deeper water (Lowe-McConnel, 1987).  A sudden 
change of temperature of 5 °C will stress or even kill fish, this formed the basis of 
acclimatization of fish especially when transporting them (Wootton, 1996). Generally, 
temperature has a pronounced effect on the rate of chemical and biological processes 
in water. For some processes such as the rate of oxygen consumption, an increase in 
temperature causes an increase in these rates until the lethal temperature is reached. 
Therefore, there is an optimum temperature at which the rate of oxygen consumption 
is maximal. At temperatures lower or higher than the optimum, the rate of oxygen 
consumption declines (Shreeder, 1975). 
Rapid breathing of fish and increase in the amplitude of respiratory movement are 
caused by a decline of oxygen supply (Mason, 1991). A marked increase in opercula 
movement of three-spined stickleback (Geasterosteus aculeatus) when placed in 
deoxygenated water for 28 minutes was reported by Mason (1991). A rapid decline in 
the movement was followed. The rate of opercular movement gradually returned to 
normal when the water was re-aerated. Organic pollution causes depletion of oxygen, 
which causes increase in the ventilation volumes of fishes and cardiac output is 
reduced at low levels of oxygen. This reduces the rate of passage of blood through the 
gills, therefore prolonging the period of time for oxygen and also conserving oxygen 
by reducing muscular work. 
Heavy metals may enter fin-and shell-fishes through direct absorption from the water 
through their gills and other exposed membranes (Matagi, 1996). However, most 
pollutants in aquatic organisms pass through the food chain (Olaniyan, 1975). Firstly, 
phytoplankton, bacteria, fungi and other small organisms absorb these substances and 
are in turn eaten by fishes (Fagade and Olaniyan, 1974; King and Jonathan, 2003). 
Heavy metal contamination of fish has adverse effect on humans and wildlife, 
because the consumption of fish is the primary route of heavy metal exposure in the 
aquatic evironment (Albaret and Lae, 2003). Fufeyin and Egborge (1998) reported the 
presence of unacceptable levels of mercury and lead in the tissues of the African 
catfish, Clarias gariepinus from Ikpoba River. Oreochromis niloticus and C. 
 
 
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gariepinus cultured in some disused mining lakes have been shown to bioaccumulate 
higher concentration of Copper, Iron, Magnesium, and Zinc in their muscle, liver and 
gill tissues. They also reported that heavy metal concentrations in aquatic fauna are 
often proportional to the levels in the aquatic environment in which the fauna resides. 
Variation in the feeding habits of fish species can be a function of the levels of heavy 
metal found in their tissues (Wootton, 1996). Reash (1986) showed that mercury 
concentrations in edible muscles of pelagic fish species are lower than those of 
benthic fish species. Continuous pollution of our streams, rivers, lagoons, estuaries, 
creeks and other surface water bodies constitute significant threat to aquatic flora and 
fauna, posing considerable setback to fishing either for recreation or commercial 
purposes, and ultimately constitute adverse health hazards to humans (Chapman and 
Kimstach, 1992). 
 
2.9 Impacts of solid waste on physico–chemical qualities of water 
When large amount of organic matter and soil materials are washed into water bodies, 
it can raise the biochemical oxygen demand of the water and this can deplete the 
water of dissolved oxygen, therefore creating anoxic condition. Therefore, fish kills 
might result due to asphyxiation (Pidgeon, 2001).  
Biochemical oxygen demand refers to the ability of organic material to reduce 
dissolved oxygen in water. Bacteria remove oxygen from water as they metabolize 
organic materials high in biochemical oxygen demand. The oxygen depletion 
eventually results in the death of not only the bacteria, but of oxygen–dependent 
aquatic species. The subsequent decomposition of the bacteria will further reduce 
dissolved oxygen concentration in water.  
Ikem et al. (2002) observed poor qualities of groundwater near two waste sites in 
Ibadan and Lagos. The results of pH, conductivity, TDS, chloride, nitrate, ammonia, 
chemical oxygen demand, aluminium, cadmium, chromium, iron, lead, nickel and 
total coliforms all exceeded the World Health Organization (WHO) standards for 
drinking water irrespective of source of pollution. Some samples were polluted with 
aluminium, cadmium, chromium, iron, lead, nickel and total coliforms greater than 
zero. Some Ibadan wells were polluted with ammonia due to seepage from sewage 
tanks into drinking wells. Aderemi et al. (2011) observed high electrical conductivity 
 
 
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and total dissolved solids in eight groundwater samples near a municipal waste 
dumpsite in Lagos, Nigeria.  
Chofqi et al. (2004), on their analysis of wells located from landfill sites, observed 
high salinity related to sea water intrusion (Younsi et al., 2001; El Achheb, 2002), 
nitrate concentration of more than 50 % of the wells exceeding 50mg/L (OMS, 1993), 
high contents of organic and inorganic chemicals, more than 4.5 mS/cm in electrical 
conductivity, 1600 mg/L in chloride, 1000 mg/L in sulphate, 15 – 25 µg/L in 
cadmium and 60 – 100 µg/L in chromium and high concentrations of heavy metals, 
and high chemical oxygen demand.  
 
 
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CHAPTER THREE 
MATERIALS AND METHODS 
3.1 Description of the study area 
Ibadan is the capital of Oyo state in Nigeria, West Africa. It has a land size covering 
2 
an area of 3 123.30 km (Tomori, 2008) and with human population of 2,550,593 by 
2006 census (National Population Commission, 2007). The city lies approximately on 
0 0
the longitude 3 5` East of Greenwich Meridian and latitude 7 23` North of the 
Equator at a distance of some 145 km northeast of Lagos (Tomori, 2008). 
Ibadan is directly connected to many cities and towns in Nigeria, as its rural 
hinterland by a system of roads, railways and air routes. The physical setting of the 
city consists of ridges of hills that run approximately in northwest – southeast 
direction (Tomori, 2008). 
Ibadan is made up of eleven local government areas with five urban local government 
areas in the city and six semi-urban local government areas in the less city. The five 
urban local government areas in the city are Ibadan North, Ibadan Northeast, Ibadan 
Northwest, Ibadan Southeast, and Ibadan Southwest while the six semi-urban local 
government areas in the less city are Ido, Egbeda, Oluyole, Akinyele, Ona Ara and 
Lagelu. 
According to Tomori (2008), there are three residential patterns in Ibadan. These are: 
- Core area, inhabited largely by the indigenous Ibadan population. This is a 
high density area of compound disintegration. 
- Low to medium quality residential areas where population densities are the 
order of 400 people per hectare. 
- High class government reservation areas that have low population and housing 
densities of 4 to 8 houses per hectare.
 
 
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Within the core area, there is lack of comprehensive water and sewage systems, 
inadequate garbage collection and disposition and unstable urban environment. 
Vegetation pattern in Ibadan is a patchwork of broken forest, savannah woodland, 
dense thickets and large tracts of forbs vegetation dominated by Chromolaena 
odorata (Siam weed) (Eupatorium) (Fagbami, 1976). 
Ibadan is naturally drained by four rivers with many tributaries: Ona River in the 
north and west; Ogbere River towards the east; Ogunpa River flowing through the 
city and Kudeti River in the central part of the metropolis. Ogunpa River is a third-
2
order stream with a channel length of 12.76 km and a catchment area of 54.92 km  
(https://en.wikipedia.org/wiki/Ibadan). Kudeti and Ogbere rivers are tributaries of 
Ogunpa river. 
 
3.1.1 Sampling sites 
A dumpsite each from ten local government areas was sampled; five streams 
receiving domestic wastes from five local government areas and five dumpsites from 
the other five local government areas. Oluyole local government area was excluded 
from the sampling because it is located on the outskirt of Ibadan and the major rivers 
in Ibadan metropolis empty into the major river (Odo Ona) located within the local 
government area. 
Figure 3.1 shows the map of the study area with the sampling locations. Earthworms, 
soil, streams and ground water (wells close to the dumpsites) were sampled. For the 
streams, upstream and downstream of the flow of water were sampled. The sampling 
points were located with the aid of a Geographical Positioning System GPS 76 
Garmin model The sampling locations are as follows: 
Irefin 
This is located at Ibadan Northeast local government area. Irefin stream was chosen 
for sampling (Plate 3.1). There are residential buildings around the stream with 
drainages channelled into it; a piggery is also very close to the site and wastes from 
the piggery are washed into the stream. There are refuse heaps along the stream, 
residents defaecate directly into it and around its bank.  
 
 
 
 
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Figure 3.1: The map of Ibadan showing the sampling stations 
 
  
 
 
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The soil around the banks of Irefin stream and the upstream and downstream of the 
0
stream were sampled. The upstream is located on longitudes 3 54’50.3” E and 
0 0
7 23’20.3” N while the downstream of is located on longitudes 3 54’50.8” E and 
0
7 23’21.7” N. This was about 400 m from the upstream. 
 
Gege 
This is located at Ibadan Southwest local government area. Gege stream (Plate 3.2) 
and a well very close to the stream were sampled. The stream receives domestic 
wastes. Residential buildings surround the site and the residents defecate directly into 
the stream. There are refuse heaps along the stream. A petrol station is very close to it 
and oil from the station might probably spill into the stream; drainages from 
residential buildings enter the stream, and a bakery is very close to it. The sampled 
well is the source of water for the production of bread. People around the area also 
depend on it for drinking and domestic purposes. 
The soil around the banks of Gege stream, the upstream and downstream of the 
stream and a well close to the stream were sampled. The upstream is located on 
0 0
longitudes 3 53’26.9” E and latitudes 7 22’27.2” N while the downstream is located 
0 0
on longitudes 3 53’25.2” E and latitudes 7 22’29.1” N. The downstream was about 
0
400 m from the upstream. The sampled well is located on longitudes 3 53’24.8” E and 
0
latitudes 7 21’28.9” N and it is about 100 m away from the stream. 
 
Gbagi 
This is located at Egbeda local government area. Around this station, there is a market 
and an abattoir. The activities around this site include slaughtering of animals, 
burning of animal hides, refuse dump, market wastes dump, animal wastes dump and 
human defaecation. Gbagi (odo eran) stream in the location was sampled (Plate 3.3). 
The soil around the banks of Gbagi stream, the upstream and downstream of Gbagi 
0
stream were sampled. The upstream is located on longitudes 2 57’20.1” E and 
0 0
latitudes 7 22’26.3” N while the downstream is on longitudes 3 57’20.6” E and 
0
latitudes 7 23’25.3” N. This downstream was about 500 m from the upstream. 
 
 
 
 
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RB 
VG 
SW 
ST FN 
 
 
Plate 3.1: Irefin stream 
 
RB – Residential building, VG – Vegetation, SW – Solid wastes, ST – The stream, 
FN – Faeces in nylon. 
 
 
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RB 
VG 
SW 
HB 
GA 
FN 
ST 
 
 
Plate 3.2: Gege stream 
 
RB – Residential building, VG – Vegetation, SW – Solid wastes, ST – The stream, 
FN – Faeces in nylon, HB – Human being defaecating directly into the stream, GA – 
Grazing animal.  
 
 
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MB 
MW 
VG 
SW 
ST 
MA 
 
 
Plate 3.3: Gbagi stream 
 
MB – Market building, MW – Market waste, SW – Solid wastes, VG – Vegetation, 
ST – The stream, MA – Meat from abattoir. 
 
 
 
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Odinjo 
This is located at Ibadan Southeast local government. Odinjo stream and a well close 
to its downstream were sampled (Plate 3.4). Around the upstream, there is a car wash 
and a food canteen. Around the downstream, there is a vehicle panel beating shop. 
The soil around the banks of Odinjo stream, its upstream and downstream were 
0 0
sampled. The upstream is located on longitudes 3 55’05.4” E and latitudes 7 21’25.6” 
0
N while the downstream is located on longitudes 3 55’05.0” E and latitudes 
0
7 21’24.9” N and this was about 500 m from the upstream. 
0
The well located at the downstream of Odinjo is located on longitudes 3 55’04.5” E 
0
and latitudes 7 21’24.9” N. It was about 50 m from the stream. 
 
Omi Adio 
Omi Adio is located in Ido Local government area. Omi Adio stream where wastes 
are dumped was sampled (Plate 3.5). The stream flows along the Apata - Abeokuta 
road. An auto-mechanic workshop, saw mill, block industry, car wash, welding shop 
and food canteens were very close to the stream. Canals run along the dumpsite. Rail 
line runs along the canals to some point.  
The soil around the banks of the Omi Adio stream, the upstream and downstream of 
0
the stream were sampled. The upstream is located on longitudes 3 45’00.9” E and 
0 0
latitudes 7 23’33.2” N while the downstream is located on longitudes 3 45.014’ E and 
0
latitudes 7 23.53.7’ E. This was about 500 m from the upstream. 
 
Ojokondo  
This is located at Ibadan north local government area. A dumpsite located on 
0 0
longitudes 3 54’32” E and latitudes 7 31’39.2” N within the residential area (Plate 
3.6) was sampled. An auto-mechanic workshop and a food canteen are located at the 
upper part of the dumpsite. There are two wells around the dumpsite; one is found at 
the upper part before getting to the dumpsite and the other one is located after the 
dumpsite (downslope). These two wells were also sampled. 
The well at the upper part; just before the Ojokondo dumpsite is located on longitudes 
0 0
3 54’31.1” E and latitudes 7 26’39.2” N. This was about 200 m before the dumpsite. 
  
 
 
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RB 
CW 
VG 
RD 
SW 
ST 
 
 
Plate 3.4: Odinjo stream 
 
SW – Solid wastes, VG – Vegetation, ST – The stream, RB – Residential building, 
CW – Car wash, RD – Road. 
 
 
 
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ST 
VG 
SW 
 
 
Plate 3.5: Omi Adio stream 
 
ST – The stream, VG – Vegetation, SW – Solid wastes 
 
 
 
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The well located at the down slope, after the Ojokondo dumpsite is located on 
0 0
longitudes 3 54’32.5” E and latitudes 7 26’39.8” N. This was about 200 m after the 
dumpsite. 
 
Olodo 
This is located at Lagelu local government area. A dumpsite was chosen for sampling 
0 0
(Plate 3.7). This is located on longitudes 4 00’13.3” E and latitudes 7 26’0.1” N. The 
dumpsite is surrounded by developing buildings. Block molding factory and metal 
fabricating shop are nearby the dumpsite. A well close to the dumpsite was also 
0 0
sampled. It is located on longitudes 4 00’12.7” E and latitudes 7 26’03.5” N. This 
was about 100 m from the dumpsite. 
 
Moniya 
This is located at Akinyele local government area. There is a dumpsite stretching 
0
about 250 meters (Plate 3.8) located on longitudes 3 54’38.8” E and latitudes 
0
7 31’28.3” N. A high tension cable runs along and across the dumpsite. Mechanic 
workshops and motor parks are situated near the site. A well in a residential 
compound down the dumpsite was also sampled. The well is very close to the 
0 0
dumpsite and it was located on longitudes 3 54’36.5” E and latitudes 7 31’30.1” N. 
This was located downslope after the dumpsite and about 200 m distance from where 
the dumpsite starts. 
 
Idi Ope 
This is located at Ibadan northeast local government. A dumpsite located on 
0 0
longitudes 3 51’51.6” E and latitudes 7 24’50.3” N was sampled (Plate 3.9). The 
dumpsite is behind an abandoned National Horticulture Research Institute (NIHORT) 
garden which is now being used as garri and fufu processing industry. Residential 
buildings and a car wash border the site. A well in a residential compound very close 
0
to the dumpsite was also sampled. The well is located on longitudes 3 51’51.0” E and 
0
latitudes 7 24’50.4” N. This was about 200 m away from the dumpsite. 
 
 
 
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RSB 
RSB 
GA SW 
 
 
Plate 3.6: Ojokondo dumpsite 
 
SW – Solid wastes, RSB – Residential storey-building, GA – Grazing animal. 
 
 
 
 
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RB 
MCH 
VG 
SW 
 
 
 
Plate 3.7: Olodo dumpsite 
 
RB – Residential building, VG – Vegetation, SW – Solid wastes, MCH – Methodist 
church. 
 
 
 
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VG 
GA 
SW 
 
 
Plate 3.8: Moniya dumpsite 
 
VG – Vegetation, SW – Solid wastes, GA – Grazing animal. 
 
 
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RB 
SW 
VG 
 
Plate 3.9: Idi Ope dumpsite 
 
RB – Residential building, VG – Vegetation, SW – Solid wastes. 
 
 
 
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Oremeji expressway 
This is located at Ona Ara local government area. A dumpsite located on longitudes 
0 0
3 55’58.0” E and latitudes 7 22’47.7” N along the Lagos - Ibadan Expressway was 
sampled (Plate 3.10). Beside the dumpsite, there is a car wash, an auto-mechanic 
workshop and a block making industry. A well is located very close to the dumpsite, 
which the car wash and block making industry use for their activities. The well is 
about 50 m away from the dumpsite. 
 
Control sites 
Two control sites were chosen for this work: 
 
Awba stream  
This is found within the University of Ibadan. This was chosen as control site for the 
stream samples. The part of the stream chosen for the research work is the one that 
flows through the Independent and Nnamdi Azikiwe halls of residence (Plate 3.11). It 
0 0
is located on longitudes 3 53’58.6” E and latitudes 7 26’26.6” N. The soil around the 
banks of the stream and the stream water were sampled.  
 
Tafawa Balewa Hall – This is a postgraduate hall of residence at the University of 
Ibadan. The soil and a well within the hall were chosen as control for the dumpsites 
0
(Plate 3.12). The sampled area is located on longitudes 3 53’52.6” E and latitudes 
0 0 0
7 26’32.0” N. The well is located on longitudes 3 53’53.3” E and latitudes 7 26’31.3” 
N within the hall and within the same area where the soil was sampled.  
 
3.2 Sampling  
A preliminary sampling of some of the dumpsites was done in February 2008 prior to 
sampling proper while the proper sampling was done from March, 2008 to February, 
2010. 
 
3.2.1 Sampling, preservation and identification of collected earthworm samples 
2
Quadrat (size 0.25 x 0.25 m ) was used to randomly sample earthworms around the 
waste sites. Digging and hand sorting methods (Reynolds, 1977) were used for the 
collection of earthworm samples on each quadrat plot. A shovel was used to dig in  
 
 
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VG 
CH 
SW 
 
 
Plate 3.10: Oremeji dumpsite 
 
VG – Vegetation, SW – Solid wastes, CH – Church. 
 
 
 
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ST 
 
 
Plate 3.11: Control stream (Awba stream, UI) 
 
ST – The stream 
 
 
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BH 
VG 
 
 
Plate 3.12: Control site for dumpsite (Tafawa Balewa Hall, UI) 
 
BH – Balewa Hall, VG – Vegetation. 
 
 
 
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blocks up to 30 cm straight into the mud in four different places (square), the soil was 
lifted on to a flat board, it was sorted and earthworms were picked with a pair of 
forceps. The earthworm samples were then preserved in formoacetic alcohol (i.e. 10 
% formalin, 2 % acetic acid, 38 % ethanol and 50 % distilled water). The preserved 
earthworms were identified in the laboratory using the keys of Owa (1992).  
 
3.2.2 Sampling, preservation and analytical methods for collected stream water 
One hundred and twenty (120) stream water samples were obtained once every two 
months from March 2008 to February 2010 from the upstreams and downstreams of 
Irefin, Gege, Gbagi, Odinjo and Omi Adio streams.  Ten (10) water samples were also 
obtained from the control stream (Awba stream) within the University of Ibadan. In 
all, a total of one hundred and thirty (130) stream water samples were collected. 
 
3.2.2.1 Physico-chemical analysis 
3.2.2.1.1 pH 
The pH of the water samples was determined on the field by electro-metric method 
using a Kent EIL 7045/46 pH meter. The pH metre was calibrated prior to use with 
buffers 4 and 7 solutions. 
 
3.2.2.1.2 Electrical conductivity 
Electrical conductivity of the water samples was determined on the field by the use of 
Extech conductivity/TDS meter model ExStik EC 400. The meter was calibrated prior 
to use with 3.3 mol solution of potassium chloride. The result was expressed as 
µS/cm. 
 
3.2.2.1.3 Total dissolved solids 
The total dissolved solids of the water samples were determined with the use of 
Extech conductivity/TDS meter model ExStik EC 400. The meter was calibrated prior 
to use with 3.3 mol solution of potassium chloride. The result was expressed as mg/L. 
 
3.2.2.1.4 Dissolved oxygen 
Samples for dissolved oxygen (DO) were collected by submerging 250 ml amber–
coloured sample bottles in water and stoppering them when filled without any air 
 
 
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bubbles (APHA, 1998). The samples were immediately treated with Winkler’s A and 
B. For each 250 ml bottle, 2 ml of Winkler’s A (Manganese sulphate) was introduced 
below the surface of the water and 2 ml of Winkler’s B (alkaline iodide-azide 
solution) was introduced at the sample surface, using wide mouth pipettes and capped 
immediately. This was followed by vigorous agitation to preserve oxygen (APHA, 
1998). 
In the laboratory, the dissolved oxygen concentration was determined using the azide 
modification of the iodometric method as reported by (APHA, 1998) and the result 
expressed as mg/L. 
 
3.2.2.1.5 Biochemical oxygen demand (BOD) 
Samples for biochemical oxygen demand (BOD) were collected by submerging 250 
ml amber–coloured sample bottles in water and stoppering them when filled without 
any air bubbles (APHA, 1998). The azide modification of the iodometric method was 
used (APHA, 1998) and the dissolved oxygen contents of the samples before and after 
o
incubation for five days at 20 C was determined. The difference from the initial and 
final DO was the BOD, expressed in mg/L.  
 
3.2.2.1.6 Chemical oxygen demand (COD) 
Samples for chemical oxygen demand and anions analysis were collected in pre-
washed 4 L polyethylene bottles and were taken to the laboratory. These were stored 
0
at 4 C before analysis.  
The chemical oxygen demand (COD) of the water samples was determined by the 
Heptaoxochromate (vi) test which involved titration (Ademoroti, 1996 and APHA, 
1998). The result was expressed in mg/L. 
 
3.2.2.1.7 Total alkalinity 
The total alkalinity due to hydroxides (strong bases), carbonate and hydrogen 
carbonate (salts of weak acids but of strong bases) of Ca, Mg, Na, and K were 
determined by titration of the sample to a color change at pH 4.6 (APHA, 1998). The 
result was expressed in mg/L. 
 
 
 
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Calculation  
Total Alkalinity as mg/L CaCO3 = VT X M X 100,000  
    ml sample 
VT = Volume of the titrant 
M = Molarity of the acid used 
 
3.2.2.2 Anions 
3.2.2.2.1 Chloride 
The method used for chloride determination was Argentometric method which 
involved titration (APHA, 1998). The result was expressed in mg/L. 
Calculation  
-
mg Cl /L = (A – B) x N x 35450  
 ml sample  
A – ml titration of sample  
B - ml titration for blank  
N – Normality of AgNO3 
 
3.2.2.2.2 Phosphate - phosphorus 
The ultraviolet spectrophotometric screening method (APHA, 1998) was used for the 
determination of phosphate in the water samples. The absorbance was measured at a 
wavelength of 470 nm using Cecil ultraviolet/visible spectrophotometer. The result 
was expressed in mg/L. 
Calculation 
mg P/L = mg P (in 50 ml final volume) X 1000 
   ml sample 
 
3.2.2.2.3 Nitrate - nitrogen 
Nitrate in water was determined by ultraviolet spectrophotometric screening method 
(APHA, 1998). The absorbance was read with Cecil ultraviolet/visible 
spectrophotometer at wavelengths of 220 nm and 270 nm. 220 nm was to determine 
nitrate reading and 270 nm was to determine interference due to organic matter.  
 
 
 
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Calculation  
For samples and standards, the absorbance reading at 220 nm was subtracted from the 
absorbance at 270 nm to obtain absorbance due to nitrate. A standard curve was 
constructed by plotting absorbance due to nitrate against nitrate-nitrogen 
concentration of standard. The result was expressed in mg/L.  
 
3.2.2.2.4 Sulphate - sulphur 
The ultraviolet screening method (APHA, 1998) was used for the determination of 
sulphate in the water samples. The absorption was measured at a wavelength of 425 
nm using Cecil ultraviolet/visible spectrophotometer. The result was expressed in 
mg/L.   
Calculation 
2- 2-
mg SO4 /L = mg SO4  X 1000 
        ml sample 
 
 
3.2.2.3 Cations (Calcium and Magnesium) 
Samples for cations (calcium and magnesium) analysis were collected in 500 ml 
containers and were immediately preserved with 0.75 ml of concentrated nitric acid 
(HNO3) prior to digestion and further analysis (APHA, 1998). The results were 
expressed in mg/L. 
 
3.2.2.4 Trace and heavy metals 
Samples for trace and heavy metals analysis were collected in 500 ml containers and 
were immediately preserved with 0.75 ml of concentrated nitric acid (HNO3) prior to 
digestion and further analysis (APHA, 1998). 
Metals determined include: 
Iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), nickel 
(Ni) and chromium (Cr). 
The above metals were analysed using the nitric acid digestion (APHA, 1998) and the 
concentrations were determined by the Alpha Atomic Absorption Spectrophotometer 
(AAS) at the Obafemi Awolowo University Central Science Laboratory. The results 
were expressed in mg/L.   
 
 
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3.2.3 Sampling, processing and analytical methods for collected soil 
Samples for soil analysis were collected from top soils (0 to 15 cm). This was done by 
using a soil auger. Soils from the banks of the streams were collected randomly and 
bulked down to one representative sample and put in well labeled polyethylene bags. 
Sixty (60) composite soil samples were collected from Irefin, Gege, Gbagi, Odinjo 
and Omi Adio stream banks. Ten (10) composite soil samples were collected from the 
control stream (Awba stream) within the University of Ibadan. 
At the dumpsites, starting at the centres of the sites, soil samples were taken in five 
directions at the North, South, East and West of the sites. Each composite sample was 
bulked down to one representative sample and put in well labeled polyethylene 
bags.Sixty (60) composite soil samples were collected from the Ojokondo, Olodo, 
Moniya, Idi Ope and Oremeji dumpsites. Ten (10) composite soil samples were 
collected from the control site (Tafawa Balewa Hall, University of Ibadan) for 
dumpsites. In all, a total of one hundred and forty (140) soil samples were collected 
from the stream banks and dumpsites once every two months from March 2008 to 
Februrary 2010. 
The soil samples were transferred on to sheets of papers and spread out to air dry in a 
0
dust-free environment at room temperature 27 C for a period of seven days in the 
laboratory of Zoology Department, University of Ibadan. After drying, the samples 
were pulverised separately with a porcelain mortar and pestle and care was taken to 
avoid contamination. Sieving of each soil sample was done through different mesh-
sized sieves depending on the mesh-size that was required for the analysis. This was 
done in order to obtain fine powder representations of each sample. 
 
3.2.3.1 Particle size distribution 
The soil samples for particle size distribution analysis were not sieved. This was 
determined by the soil Bouycous hydrometer method (Pramer and Schmidt, 1964; 
Olaitan and Lombin, 1984; and Awolumate, 1977) as described in the International 
Institute of Tropical Agricultural (IITA) laboratory manual (1979). 
50 g of air-dried soil was weighed out into a 250 ml beaker. 50 ml of NaOH 
dispersing agent (80 g NaOH dissolved in 2 L of distilled water) and 100 ml distilled 
water was added to the soil. The suspension was left to stand for 30 minutes with 
 
 
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occasional stirring. It was then transferred from the beaker to a 1 L measuring 
cylinder. The suspension was rinsed out of the beaker with distilled water until none 
was left in the beaker. This was made up to the mark with distilled water. The top of 
the measuring cylinder was covered with the palm of the hand firmly to seal it 
completely and it was shaken vigorously by turning end-cover several times until all 
the soil was in suspension. 
The cylinder was placed on the laboratory bench and the time of placement was 
noted. It was allowed to stand for 30 seconds and the soil hydrometer was gently 
inserted into the soil suspension. The hydrometer was read after 10 seconds of 
insertion. This gave the first hydrometer reading (H1). A thermometer was inserted 
into the suspension and the temperature of the suspension was taken. This gave the 
first temperature reading (T1). After the readings were taken, the suspension was left 
to stand for 2 hours. Then, the second hydrometer reading (H2) and the second 
temperature reading (T2) were taken. 
Calculation 
% Sand = 100.0 – (H1 + 0.2 (T1 – 68) – 2.0) 2 
% Clay = (H2 + 0.2 (T2 – 68 – 2.0) 2 
% Silt = 100.0 – (%Sand + % Clay) 
 T1 and T2 were converted to degrees Fahrenheit before applying the formulae above. 
This conversion from degrees Celsius to degrees Fahrenheit was done by multiplying 
by 9; product was divided by 5 and 32 added.  
0 0
i. e. F =  C x 9+ 32 
1                   5 
 
3.2.3.2 pH 
The pH of the soil samples were determined at a ratio of 1:1 soil to water ratio (Clark, 
1923; Bates, 1954; and Black, 1965) as described in the International Institute of 
Tropical Agricultural (IITA) laboratory manual (1979). 
20 g of air-dried soil which had passed through 2-mm sieve was measured into a 50 
ml beaker. 20 ml distilled water was added (ratio 1:1) and allowed to stand for 30 
minutes with occasional stirring with a glass rod. The electrode of the pH meter (Kent 
EIL 7045/46) was dipped into the partly settled suspension and the pH was measured. 
 
 
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Prior to measurement, the pH meter was calibrated with pH buffers 7.00 and 4.00 
solutions. 
 
3.2.3.3 Electrical conductivity 
The suspension of the soil pH sample was allowed to settle for thirty minutes, and 
then the electrical conductivity of the supernatant liquid was determined by Extech 
conductivity meter model ExStik EC 400 (Anderson and Ingram, 1993). The meter 
was calibrated prior to use with 3.3 mol solution of potassium chloride. The result was 
expressed in µS/cm. 
 
3.2.3.4 Total organic carbon and matter 
The soil total organic carbon was determined using colorimetric determination 
(Anderson and Ingram, 1993). The soil total organic matter was calculated from the 
result of the soil total organic carbon also suggested by Anderson and Ingram (1993). 
Calculation 
The solution concentrations for each unknown and the blanks were determined and a 
graph of absorbance against standard concentration was plotted. The mean blank 
value was subtracted from the unknowns; this gave a value for corrected 
concentration, K.  
Where W = Weight of soil 
% Organic Carbon = (K X 0.1) / (W X 0.74) 
To calculate organic matter: 
% Organic matter = % Organic carbon X 1.729 
 
3.2.3.5 Anions 
3.2.3.5.1 Nitrate  
Nitrate was determined by the turbidimetric method (Greweling and Peech, 1965) as 
described in the International Institute of Tropical Agricultural (IITA) laboratory 
manual (1979). 
The transmittance was measured at a wavelength of 470 nm using Jenway 6051 
colorimeter and the result was multiplied by 22 putting into consideration the volume 
 
 
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of extracting solution and some other reagents. The result was therefore expressed in 
mg/kg. 
 
3.2.3.5.2 Sulphate 
Sulphate was determined by the turbidimetric method (Ensminger, 1954; Fox et al., 
1964; and Tabatabai, 1974) as described in the International Institute of Tropical 
Agricultural (IITA) laboratory manual (1979). 
The transmission was measured at a wavelength of 420 nm and the result was 
multiplied by 12.5 putting into consideration the volume of extracting solution and 
some other reagents. The result was therefore expressed in mg/kg.   
 
3.2.3.6 Cations 
The cations determined include: 
Phosphorus    
Calcium 
Magnesium 
Sodium 
Potassium 
Extractable phosphorus was determined by colorimetric (Bray No. 1) method 
according to Bray and Kurtz (1945) and Jackson (1962) as described in the 
International Institute of Tropical Agricultural (IITA) laboratory manual (1979). 
The transmittance was measured at a wavelength of 600 nm using Jenway 6051 
colorimeter and the result was multiplied by 28 putting into consideration the volume 
of extracting solution and some other reagents. The result was therefore expressed in 
mg/kg.   
All other cations were determined using the Alpha Atomic Absorption 
Spectrophotometer after nitric – hydrochloric acid digestion according to the method 
described by Chen and Ma (2001).  
The results of all cations were expressed in mg/kg. 
 
 
 
 
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3.2.3.7 Cation exchange capacity (CEC) 
The cation exchange capacity of the soil samples were analysed using one of the 
calculation methods described by Madeira et al. (2003) with some modifications. It 
was done by the addition of values of calcium, magnesium, potassium and sodium. 
The modification was the non-addition of aluminium since aluminium was not 
analysed. Before the addition, the mg/kg units of the cations were first converted to 
millimoles/kg by dividing the result in mg/kg by the equivalent weight of each cation 
and then converting back to centimole/kg by dividing it by 10 (NRES497-3, 2012). 
 
3.2.3.8 Trace and heavy metals 
The trace and heavy metals determined include: 
Iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), nickel 
(Ni) and chromium (Cr). 
All the above were determined using the lpha Atomic Absorption 
Spectrophotometer after nitric – hydrochloric acid digestion according to the method 
described by Chen and Ma (2001). Their results were expressed in mg/kg. 
 
3.2.4 Sampling, preservation and analytical methods for collected groundwater 
Groundwater samples were collected from groundwater wells via a pulley system. 
Twenty two (22) samples were obtained once every two months from March 2008 to 
February 2010 from the wells close to the Gege and Odinjo streams; seventy-two (72) 
samples from the wells close to Idi Ope, Moniya, Olodo, Oremeji, before Ojokondo 
and after the Ojokondo dumpsites; and ten (10) samples from the control well located 
at the Tafawa Balewa Hall of Residence in the University of Ibadan. In all a total of 
one hundred and four (104) well water samples were collected. 
The samples were collected in pre-washed 4 L polyethylene bottles and taken to the 
0
laboratory for storage at approximately 4 C until analysis was carried out. All the 
parameters determined for stream water samples were determined for the groundwater 
samples using the same analytical methods except dissolved oxygen content of 
groundwater samples that was not determined. 
 
 
 
 
 
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3.2.5 Toxicity assays 
The downstream water samples collected in the month of January, 2009 were the test 
solutions used for the toxicity assays in the laboratory. 
The toxicity assays for organisms exposed to the downstream water samples were 
carried out according to the method described by Obuotor and Onajobi (2000). 
 
3.2.5.1 Mayflies toxicity assay 
Cloeon perkinsi (Barnard, 1832) larvae were collected from the Opa dam of the 
th
Obafemi Awolowo University, Ile-Ife. The 9  instar larvae were selected and 
acclimated to laboratory conditions for twelve hours in holding tanks at a stocking 
0
density of 3 g/L at a laboratory temperature of 25 C. 
After acclimation, 10 larvae each were randomly assigned to the test chambers 
(cylindrical glass containers with volume capacity of 175 ml) in quadruplicates. Each 
test chamber contained 150 ml of appropriately diluted test solutions (downstream 
water samples) to give a final concentration of 50 %, 25 %, 12.5 %, 6.25 % and 3.125 
%. The larvae were then exposed for 48 hrs during which the mortality was monitored 
every 2 hrs for the first 24 hrs. Death was ascertained by the loss of reflex activity 
(failure to react to external prodding). 
 
Estimation of median lethal concentration 
In order to estimate the median lethal concentration and the 95 % confidence 
intervals, the mortality data were analysed using EPA Probit Analysis Program, 
Version 1.5 (USEPA, 1997) obtained from the United States Environmental 
Protection Agency website (http://www.epa.gov/nerleerd/stat2.htm).   
 
3.2.5.2  Tadpoles bioassay 
Laboratory hatched tadpoles were used for this test. The test was carried out as 
follows: To each of five test glass jars (175 ml) containing 150 ml of the appropriately 
diluted downstream water samples (50 %, 25 %, 12.5 %, 6.25 % and 3.125 %), 10 
laboratory hatched 5-day old tadpoles were introduced into each of the five test jars 
and the control. Each test concentration and the control were carried out in 
quadruplicates.  
 
 
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The tadpoles were exposed for 96 hours and the set up was monitored for mortality 
every 2 hours for the first 24 hrs.  
 
Estimation of median lethal concentration  
The mortality data were analysed by using an EPA Probit Analysis Program, Version 
1.5 (USEPA, 1997) to estimate the median lethal concentration (LC50).   
 
3.2.5.3 Fish toxicity assay 
Frys and fingerlings of Clarias gariepinus (Burchel, 1822) were used for this 
experiment. 
 
3.2.5.3.1 Clarias gariepinus frys toxicity assay 
One and a half week’s old frys of Clarias gariepinus (Burchel, 1822) were obtained 
from a commercial fish farm in Osogbo, Osun state. They were acclimated to 
laboratory conditions for seven days in holding tanks at a stocking density of 3 g/L. 
After acclimation, 10 frys each were randomly assigned to the test chambers 
(cylindrical glass containers with volume capacity of 175 ml) in quadruplicates. Each 
test chamber contained 150 ml of appropriately diluted test solutions (downstream 
water samples) to give a final concentration of 50 %, 25 %, 12.5 %, 6.25 % and 3.125 
%. The frys were then exposed for 96 hrs during which the mortality was monitored 
every 2 hrs for the first 24 hrs. Dead fish were promptly removed from the chambers. 
Death was ascertained by the loss of reflex activity (failure to react to external 
prodding). 
 
Estimation of median lethal concentration  
In order to estimate the median lethal concentration and the 95 % confidence 
intervals, the mortality data were analysed using EPA Probit Analysis Program, 
Version 1.5 (USEPA, 1997) obtained from the United States Environmental 
Protection Agency website (http://www.epa.gov/nerleerd/stat2.htm).   
 
3.2.5.3.2 Clarias gariepinus fingerlings bioassay 
Four weeks old fingerlings of Clarias gariepinus (Burchel, 1822) were obtained from 
a commercial fish farm in Osogbo, Osun state. They were acclimated to laboratory 
 
 
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conditions for seven days in holding tanks at a stocking density of 5 g/L. After 
acclimation, 10 fingerlings each were randomly assigned to the test chambers 
(cylindrical glass containers with volume capacity of 1 L) in triplicates. Each test 
chamber contained 150 ml of appropriately diluted test solutions (downstream water 
samples) to give a final concentration of 50 %, 25 %, 12.5 %, 6.25 % and 3.125 %. 
The fingerlings were then exposed for 96 hrs during which the mortality was 
monitored every 2 hrs for the first 24 hrs. Dead fish were promptly removed from the 
chambers. Death was ascertained by the loss of reflex activity (failure to react to 
external prodding). 
 
Estimation of median lethal concentration  
In order to estimate the median lethal concentration and the 95 % confidence intervals 
the mortality data were analysed using EPA Probit Analysis Program, Version 1.5 
(USEPA, 1997) obtained from the United States Environmental Protection Agency 
website (http://www.epa.gov/nerleerd/stat2.htm).   
 
3.2.5.4 Earthworms’ toxicity assay 
The earthworms’ toxicity assay was carried out with modifications of the sediment 
test procedure using freshwater oligochaetes as proposed by APHA (1998). The 
modification was that instead of using sediment for the analysis, soil samples were 
used.   
Eudrilus eugeniae (Kinberg, 1867) earthworms were collected from the Tafawa 
Balewa Hall of residence. They were fed ad libitum for a period of seven days to 
acclimatize them to laboratory conditions. 
Soil samples were collected from the various dumpsites, streams and the two control 
sites. 10 kg of each soil sample were put in test chambers in quadruplicates in the 
laboratory and 10 earthworm samples were put per chamber to determine the toxicity 
of the soil samples on earthworms. The earthworms were then exposed for 96 hours 
during which mortality was monitored. 
 
3.3 Analytical procedures for stream water, soil and groundwater 
Digestion of stream water samples and all analytical procedures for stream water and 
groundwater samples were carried out at the Pharmaceutical Chemistry Department 
 
 
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laboratory, Faculty of Pharmacy, Obafemi Awolowo University, Ile – Ife. All cations, 
trace and heavy metals analysis were carried out at the Obafemi Awolowo University 
Central Science laboratory, Ile – Ife.  
All analytical procedures for soil, except for particle size distribution were also 
carried out at the Pharmaceutical Chemistry Department laboratory, Faculty of 
Pharmacy, Obafemi Awolowo University, Ile – Ife. Particle size distribution was 
carried out at the Department of Zoology, University of Ilorin, Ilorin.  
 
3.3.1 Cations, trace and heavy metals determination in stream water: sample 
digestion 
100 ml of well-mixed, acid-preserved stream water samples were transferred into a 
250 ml beaker and 5 ml concentrated nitric acid (HNO3) was added. The beakers were 
covered with watch glasses and evaporated on a hot plate to about 10 ml. For some 
highly coloured samples, concentrated nitric acid (HNO3) was continuously added 
until digestion was shown by a light-coloured, clear solution. 
The beakers and watch glasses were then washed down with distilled water. On 
cooling, filtrate was transferred to 100 ml volumetric flask and made up to mark with 
distilled water. Blank solution was also digested. 
Cations (Ca, Mg), trace metals (Fe and Mn) as well as heavy metals (Cu, Zn, Pb, Cd, 
Ni, and Cr) were determined in the digested samples using Alpha Atomic Absorption 
Spectrophotometer (AAS). Their results were expressed in mg/L. 
 
3.3.2 Cations, trace and heavy metals determination in soil samples: sample 
digestion 
The cations (Ca, Mg, Na and K), trace (Fe and Mn) and heavy metals (Cu, Zn, Pb, Cd, 
Ni, and Cr) in the soil samples were determined by the Atomic Absorption 
Spectrophotometry as described by Chen and Ma (2001). 
A well-mixed sample of 1 g of air–dried soil sample which had passed through a 2 
1
mm mesh–sized sieve was digested in 12 ml aqua regia ( /3 HNO3 – HCl, vv, i. e. 3 ml 
0
HNO3 and 9 ml HCl) in a water bath at 100 C for 2 hours. After evaporating to near 
dryness on a hot plate, the sample was diluted with 20 ml of 2 % (v/v with water) 
nitric acid. This was cooled and filtered through Whatman No. 42 filter paper into a 
 
 
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100 ml volumetric flask. It was made up to volume with distilled water. The samples 
were then taken to the Central Science Laboratory at the Obafemi Awolowo 
University, Ile–Ife to check for the metals concentration by using Alpha Atomic 
Absorption Spectrophotometer. Their results were expressed in mg/kg. 
 
3.4 Statistical analysis 
3.4.1 Biological parameters  
Biological parameters were used in analyzing earthworms’ data. These include: 
 
3.4.1.1 Shannon Wiener’s diversity index for the measure of species’ diversity: 
1
H  = (NlogN - ∑ni logni) 
  N 
1
Where H  = Shannon Wiener’s index 
N = total number of individuals 
th
ni = observed proportion of individuals belonging to the i  species. 
 
3.4.1.2 Shannon’s Evenness measures or measures of “relative density” equitability 
given by Pielou’s (1975) equation as E = HS 
          Log s  
Where HS = Shannon Wiener’s index 
 s = number of species or taxa 
 
3.4.1.3 Menhinick’s index for the measures of species richness: 
Da = s      
      √N 
Where s = the number of species 
 N = the total number of individuals in all the species. 
 
3.4.1.4 Sorensen’s coefficient (quotient of similarity) given by Horn’s (1966) 
equation as CCS = 2C 
      S1 + S2 
 
 
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Where CCS = Sorensen coefficient 
     C = number of species common to both stations 
     S1 = number of species in site 1 
           S2 = number of species in site 2 
 
3.4.2 Graphical illustrations and descriptive statistics 
Microsoft excel 2007 (Microsoft Corporation 1985-2007) was used for all graphical 
illustrations. SPSS version 17 was used to compute the mean and standard error of 
means of all physico – chemical parameters, anions, cations, trace and heavy metals 
of all soil, stream water and groundwater samples. 
 
3.4.3 Physico-chemical parameters 
3.4.3.1 ANOVA (Analysis of variance) was used to test for the statistical differences 
between the physico-chemical qualities of soil, stream water samples and 
groundwater samples of the sample stations. 
 
3.4.3.2 Duncan’s multiple range tests was used to measure the similarities of the 
sample stations. 
 
3.4.3.3 Pearson’s correlation coefficient was used to compare the relationship 
between the parameters. 
 
3.4.4 Toxicity Assay 
Probit’s analysis using a statistical package USEPA version 1.5 (1997) was used to 
calculate the LC50 of the ecotoxicological test organisms. 
 
 
 
 
 
 
 
 
 
 
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CHAPTER FOUR 
RESULTS 
4.1 Earthworms composition and abundance during the study period 
4.1.1 Streams 
The earthworm species identified at the banks of the streams were Eudrilus euginiae, 
Dichogaster modigliani and Hyperiodrilus africanus. An additional species, Alma 
millsoni was found at the control site (Awba stream). The total population of all 
earthworm species was 778 individuals. 
The earthworms found at the bank of Gege stream accounted for the least abundance 
of the earthworms found at all the stream banks with Dichogaster modigliani and 
Hyperiodrilus africanus having the population of 5 and 3 respectively with percentage 
abundances of 0.64 % and 0.39 % respectively. Eudrilus euginiae was not found at 
the bank of the Gege stream. The population of Eudrilus euginiae, Dichogaster 
modigliani and Hyperiodrilus africanus found at the bank of the Gbagi stream were 
60, 40, 22 with percentage abundances of 7.73 %, 5.15 % and 2.84 % respectively. At 
the bank of Irefin stream, the population of Eudrilus euginiae, Dichogaster 
modigliani and Hyperiodrilus africanus were 8, 2 and 6 respectively with percentage 
abundances of 1.03 %, 0.26 % and 0.77 % respectively. Hyperiodrilus africanus was 
not found throughout the study period at the Odinjo site while population of Eudrilus 
euginiae and Dichogaster modigliani were 72 and 28 respectively with percentage 
abundances of 9.28 % and 3.61 % respectively for the two. At the Omi Adio site, the 
Eudrilus euginiae, Dichogaster modigliani and Hyperiodrilus africanus population 
were 39, 24 and 21 respectively with the percentage abundances of 5.03 %, 3.09 % 
and 2.71 % respectively.  The earthworms found at the bank of the control site (Awba 
stream) were the most abundant. The population of Eudrilus euginiae, Dichogaster 
modigliani and Hyperiodrilus africanus were 87, 188, 152 and 22 respectively with 
percentage abundances of 11.21 %, 24.22 %, 19.56 % and 2.71 % respectively. It was 
only the control site that recorded more than two species of earthworms at any 
particular time during the sampling period (Figure 4.1a; Appendix 1). 
 
 
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Eudrilus euginiae 
 
 
Hyperiodrilus africanus 
 
 
 
 
Dichogaster modigliani 
 
Plate 4.1: Earthworms encountered at the streams and dumpsites during the 
study period
64 
 
 
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During the wet season of the sampling period, all earthworm species were found at 
the streams’ banks except Alma millsoni. At the Irefin stream bank, all the 
earthworms present were found during the wet season (Eudrilus euginiae – 8 
individuals, Dichogaster modigliani – 2 individuals and Hyperiodrilus africanus – 6 
individuals) while no earthworm was found during the dry season. Earthworms 
observed at the Gege stream bank were present during the wet season (Dichogaster 
modigliani - 5 individuals and Hyperiodrilus africanus – 3 individuals), none was 
found during the dry season. At the Gbagi stream bank, 48, 40 and 22 individuals of 
Eudrilus euginiae, Dichogaster modigliani and Hyperiodrilus africanus respectively 
were obtained during the wet season. It was only 12 individuals of Eudrilus euginiae 
that were observed during the dry season. At the Odinjo stream bank, 69 and 28 
individuals of Eudrilus euginiae and Dichogaster modigliani respectively were 
observed during the wet season. Eudrilus euginiae (3) were also observed during the 
dry season. Omi Adio stream banks had 24, 24 and 14 individuals of Eudrilus 
euginiae, Dichogaster modigliani and Hyperiodrilus africanus respectively during the 
wet season. The earthworms observed during the dry season were 15 individuals of 
Eudrilus euginiae and 7 individuals of Hyperiodrilus africanus. The control site 
(Awba stream) recorded the highest number of individual earthworms during the two 
seasons. Individuals of Eudrilus euginiae, Dichogaster modigliani and Hyperiodrilus 
africanus found during the wet season were 132, 162 and 87 respectively. During the 
dry season, there were 20 and 26 individuals of Eudrilus euginiae and Dichogaster 
modigliani respectively. No Hyperiodrilus africanus was found during the dry season. 
An additional earthworm species, Alma millsoni (21 individuals) was found during the 
dry season and was only present at the control site (Awba stream) (Figures 4.1b; 
Appendix 2). 
 
4.1.2 Dumpsites 
Throughout the study period, Eudrilus euginiae, Dichogaster modigliani and 
Hyperiodrilus africanus were the three species of earthworms identified at the 
dumpsites and the control site (Balewa) (Appendix 3). A total population of 1,140 
individuals of earthworms was found throughout the sampling period. 
The least population of earthworms found at the soil from dumpsites and control were 
observed at the Ojokondo dumpsite with the population of Eudrilus euginiae, 
Dichogaster modigliani and Hyperiodrilus africanus being 33, 28 and 3 respectively 
 
 
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30 Alma millsoni 
Eudrilus euginiae 
25 Dichogaster modigliani 
Hyperiodrilus africanus 
20 
15 
10 
5 
0 
Sampling Locations 
 
 
180 
160 Irefin 
140 Gege 
Gbagi 
120 
Odinjo 
100 
Omi-Adio 
80 
Awba stream 
60 
40 
20 
0 
Wet Dry Wet Dry Wet Dry Wet Dry 
Eudrilus Dichogaster Hyperiodrilus Alma millsoni 
euginiae modigliani africanus 
Earthworm Species 
 
Figure 4.1: a) Percentage abundance of earthworms at the streams’ banks 
        b) Seasonal variation of earthworm species at the streams’ banks 
 
 
UNNIumber of Individual Earthworms Percentage Abundance (%) VERSITY OF IBADAN LIBRARY
 
with percentage abundances of 2.89 %, 2.46 % and 0.26 % respectively. At the Olodo 
dumpsite, the population of Eudrilus euginiae, Dichogaster modigliani and 
Hyperiodrilus africanus were 38, 46 and 8 respectively while their abundance patterns 
were 3.33 %, 4.04 % and 0.70 % respectively. The population of Eudrilus euginiae 
and Dichogaster modigliani observed at the Moniya dumpsite were 64 and 52, while 
their percentage abundances were 2.98 % and 4.56 % respectively. Hyperiodrilus 
africanus was not found at the Moniya dumpsite throughout the study period. At the 
Idi Ope dumpsite, Dichogaster modigliani was not found throughout the study period. 
However, the population of Eudrilus euginiae and Hyperiodrilus africanus were 56 
and 12 respectively while their abundances were 4.91 % and 1.05 % respectively. The 
populations of the earthworms obtained at the Oremeji dumpsite were 39, 27 and 22 
for Eudrilus euginiae, Dichogaster modigliani and Hyperiodrilus africanus 
respectively while their abundance patterns were 3.42 %, 2.37 % and 1.93 % 
respectively. The highest populations of earthworms were observed at the control site 
(Balewa) with Eudrilus euginiae, Dichogaster modigliani and Hyperiodrilus 
africanus being 241, 262 and 209 respectively while their abundances were 21.14 %, 
22.98 % and 18.33 % respectively (Figure 4.2a; Appendix 3). 
All species of earthworms were found during the wet season at the dumpsites. At the 
Ojokondo dumpsite, 33, 28 and 3 individuals of Eudrilus euginiae, Dichogaster 
modigliani and Hyperiodrilus africanus respectively were found during the wet 
season. The individuals of Eudrilus euginiae, Dichogaster modigliani and 
Hyperiodrilus africanus found at the Olodo dumpsite during the wet season were 8, 
46 and 8 respectively. At the Moniya dumpsite, 64 and 52 individuals of Eudrilus 
euginiae and Dichogaster modigliani respectively were observed during the wet 
season. Individuals of Eudrilus euginiae and Hyperiodrilus africanus observed at the 
Idi Ope dumpsite during the wet season were 56 and 12 respectively. At the Oremeji 
dumpsite, individuals of Eudrilus euginiae, Dichogaster modigliani and 
Hyperiodrilus africanus were 39, 27 and 22 respectively. During the wet season, 
individuals of Eudrilus euginiae, Dichogaster modigliani and Hyperiodrilus africanus 
observed at the control site (Balewa) were 228, 241 and 196 respectively. It was the 
only site that had the three earthworm species present during the dry season.  
 
Individuals of Eudrilus euginiae and Hyperiodrilus africanus observed were 13 each. 
Dichogaster modigliani were 21 individuals (Figures 4.2b; Appendix 4). 
 
 
UNIVERSITY OF IBADAN LIBRARY
 
 
4.2 Earthworms’ density and biomass  
4.2.1 Streams 
The densities of Eudrilus euginiae earthworms found at the banks of the streams 
2 2
ranged from 0 to 8 individuals/m  (8.00±0.00 individuals/m ) at the Irefin stream, 3 to 
2 2
25 individuals/m  (14.00±9.52 individuals/m ) at the Gbagi stream, 4 to 16 
2 2
individuals/m  (12.67±5.32 individuals/m ) at the Odinjo stream and 3 to 13 
2 2
individuals/m  (8.00±4.62 individuals/m ) at the Omi Adio dumpsites, 9 to 27 
2 2
individuals/m  (22.40±8.29 individuals/m ) at the control site (Awba stream). Their 
2 2 2 2
biomasses were 0 to 5.76 g/m  (5.76±0.00 g/m ), 3.2 to 5.4 g/m  (10.06±6.10 g/m ), 
2 2 2 2
4.4 to 15.24 g/m  (11.54±3.98 g/m ), 2.28 to 13.68 g/m  (7.24±5.37 g/m ) and 8 to 28 
2 2
g/m  (25.47±10.55 g/m ) at the Irefin, Gbagi, Odinjo and Omi Adio and the control 
streams respectively (Appendix 1).  
The densities of Dichogaster modigliani earthworms found at the banks of the streams 
2 2
ranged from 0 to 4 individuals/m  (4.00±0.00 individuals/m ) each at the Irefin and 
2 2
Gege streams, 0 to 40 individuals/m  (40.00±0.00 individuals/m ) at the Gbagi 
2 2
stream, 6 to 22 individuals/m  (14.00±8.42 individuals/m ) at the Odinjo stream, 3 to 
2 2
17 individuals/m  (10.67±6.11 individuals/m ) at the Omi Adio dumpsites and 18 to 
2 2
31 individuals/m  (25.33±3.27 individuals/m ) at the control site (Awba stream). 
2 2 2 
Their biomasses were 0 to 0.96 g/m  (0.96±0.00 g/m ), 0 to 1.84 g/m (1.84±0.00 
2 2 2 2 2
g/m ), 0 to 32.84 g/m  (32.84±0.00 g/m ), 5.12 to 15.08 g/m  (10.10±7.04 g/m ), 1.56 
2 2 2 2
to 10.20 g/m  (6.84±4.62 g/m ) and 17.36 to 42.16 g/m  (29.94±31.44 g/m ) at the 
Irefin, Gege, Gbagi, Odinjo, Omi Adio and the control streams respectively 
(Appendix 1).    
Hyperiodrilus africanus densities found at the banks of the streams ranged from 0 to 4 
2 2 2
individuals/m  (4.00±0.00 individuals/m ) at the Irefin stream, 0 to 20 individuals/m  
2 2
(20.00±0.00 individuals/m ) at the Gbagi stream, 7 to 13 individuals/m  (10.00±2.83 
2 2
individuals/m ) at the Omi Adio dumpsites and 23 to 29 individuals/m  (26.00±2.31 
2
individuals/m ) at the control site (Awba stream). Their range and mean biomasses 
2 2 2 2
were 0 to 1.72 g/m  (1.72±0.00 g/m ), 0 to 15 g/m (15.00±0.00 g/m ), 4.40 to 7.16 
2 2 2 2
g/m  (5.78±1.95 g/m ) and 27.76 to 31.44 g/m  (30.04±3.06 g/m ) at the Irefin, Gbagi,  
 
 
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25.00 
20.00 
15.00 
Eudrilus euginiae 
10.00 
Dichogaster 
modigliani 
5.00 
Hyperiodrilus 
africanus 
0.00 
Sampling Locations 
 
300 
250 
200 
Ojokondo 
150 
Olodo 
Moniya 
100 
Idi Ope 
Oremeji 
50 
Balewa 
0 
Wet Dry Wet Dry Wet Dry 
Eudrilus Dichogaster Hyperiodrilus 
euginiae modigliani africanus 
Earthworm Species 
 
Figure 4.2: a) Percentage abundance of earthworms at the dumpsites 
                b) Seasonal variation of earthworm species at the dumpsites  
 
 
UN Percentage Abundance (%) Number of Individual Earthworms IVERSITY OF IBADAN LIBRARY
 
Omi Adio and the control streams respectively (Appendix 1).        
The analysis of the streams showed that the density of Alma millsoni found at the 
2
control site (Awba stream) ranged from 2.37 to 20.95 individuals/m  (17.32±2.31 
2 2 2
individuals/m ) and biomass ranged from 3.80 to 15.95 g/m  (12.04±1.98 g/m ) 
(Appendix 1).  
 
4.2.2 Dumpsites 
The densities of Eudrilus euginiae earthworms found in the soils from the dumpsites 
2 2
ranged from 3 to 8 individuals/m  (6.40±2.19 individuals/m ) at the Ojokondo 
2 2
dumpsite, 4 to 10 individuals/m  (9.00±3.83 individuals/m ) at the Olodo dumpsite, 4 
2 2
to 10 individuals/m  (8.50±5.83 individuals/m ) at the Moniya dumpsite, 3 to 9 
2 2
individuals/m  (8.00±4.00 individuals/m ) at the Idi Ope dumpsites, 7 to 11 
2 2
individuals/m  (9.00±2.00 individuals/m ) at the Oremeji dumpsite and 15 to 36 
2 2
individuals/m  (30.00±13.69 individuals/m ) at the control site (Balewa). Their 
2 2 2
biomasses were 1.80 to 7.52 g/m  (4.22±2.62 g/m ), 4.04 to 9.44 g/m  (7.12±2.25 
2 2 2 2 2
g/m ), 1.76 to 13.76 g/m  (6.12±2.46 g/m ), 1.84 to 10.04 g/m  (6.80±5.38 g/m ), 3.56 
2 2 2 2
to 10.04 g/m  (7.64±4.23 g/m ) and 5.80 to 49.84 g/m  (36.04±24.29 g/m ) at the 
Ojokondo, Olodo, Moniya and Idi Ope, Oremeji and the control site (Balewa) 
respectively (Appendix 3).  
The densities of Dichogaster modigliani earthworms found in the soils of the 
2 2
dumpsites ranged from 7 to 9 individuals/m  (6.00±2.31 individuals/m ) at the 
2 2
Ojokondo dumpsite, 5 to 17 individuals/m  (9.60±6.07 individuals/m ) at the Olodo 
2 2
dumpsite, 9 to 16 individuals/m  (12.00±4.00 individuals/m ) at the Moniya dumpsite, 
2 2
4 to 13 individuals/m  (9.33±4.62 individuals/m ) at the Oremeji dumpsite and 13 to 
2 2
56 individuals/m  (32.00±12.65 individuals/m ) at the control site (Balewa). Their 
2 2 2 
biomasses were 1.80 to 5.28 g/m  (4.15±1.60 g/m ), 1.16 to 10.12 g/m (5.04±4.03 
2 2 2 2 2
g/m ), 7.36 to 13.84 g/m  (11.20±3.40 g/m ), 0.84 to 10.40 g/m  (6.55±5.04 g/m ) and 
2 2
9.24 to 80.56 g/m  (36.23±18.68 g/m ) at the Ojokondo, Olodo, Moniya, Oremeji 
dumpsites and the control site respectively (Appendix 3).    
Hyperiodrilus africanus densities found in the soils of the dumpsites ranged from 0 to 
2 2
4 individuals/m  (4.00±0.00 individuals/m ) at the Ojokondo dumpsite, 0 to 8 
2 2
individuals/m  (8.00±0.00 individuals/m ) at the Olodo dumpsite, 4 to 8 
2 2
individuals/m  (6.00±2.83 individuals/m ) at the Idi Ope dumpsite, 7 to 17 
 
 
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2 2
individuals/m  (12.00±5.66 individuals/m ) at the Oremeji dumpsite and 13 to 52 
2 2
individuals/m  (32.67±14.62 individuals/m ) at the control site (Balewa). Their range 
2 2 2 
and mean biomasses were 0 to 2.00 g/m  (2.00±0.00 g/m ), 0 to 2.80 g/m (2.80±0.00 
2 2 2 2 2
g/m ), 1.84 to 8.96 g/m  (5.78±1.95 g/m ), 3.56 to 18.88 g/m (11.20±10.75 g/m ), 
2 2
and 6.56 to 73.27 g/m  (41.03±25.35 g/m ) at the Ojokondo, Olodo, Idi Ope, Oremeji 
dumpsites and the control site (Balewa) respectively (Appendix 3).        
 
4.3 Earthworms’ diversity 
4.3.1 Streams  
Shannon Wiener’s diversity index showed that earthworms were mostly diverse in the 
soil at the Odinjo site (0.73), followed by the control site (0.57), Omi Adio (0.47), 
Irefin (0.45), Gbagi (0.44), while the least was at Gege (0.30) (Table 4.1). 
The Shannon’s evenness index showed that earthworms were most evenly distributed 
in the soil at the Odinjo site (2.43), followed by Gege (1.00), Omi Adio (0.98), control 
site (Awba stream) (0.95) and Irefin (0.95) were equally evenly distributed and the 
least was Gbagi (0.92) (Table 4.1). 
Maximum species richness in terms of Menhinick’s index was recorded at Gege 
(2.03), followed by Irefin (1.42), Omi Adio (0.66), Odinjo (0.6), Gbagi (0.5) and the 
control site (Awba stream) (0.38) was the minimum (Table 4.1). 
The Sorensen’s coefficient of community similarity showed that the most similar sites 
in earthworms’ composition were Gbagi and Irefin (1.00), Omi Adio and Irefin (1.00), 
Omi Adio and Gege (1.00), and Omi Adio and Gbagi (1.00). The least similar sites 
were the control site (Awba stream) and Gege (0.67), and also the control site (Awba 
stream) and Odinjo (0.67) (Table 4.2). 
 
4.3.2 Dumpsites 
Shannon Wiener’s diversity index showed that earthworms were mostly diverse at the 
control site (Balewa) (0.52), Oremeji site (0.50), followed by Olodo (0.49), Ojokondo 
(0.38), Idi Ope (0.37) while the least was at Moniya (0.27) (Table 4.3). Shannon’s 
evenness index showed that earthworms were most evenly distributed at the control  
 
 
 
 
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Table 4.1: Diversity indices of earthworms observed at the streams  
Sites    Shannon             Shannon’s  Menheinick’s 
    Weiner   Evenness   Species Richness 
                                 Diversity  Index              Index 
 
 
Awba stream     0.57       0.95    0.38 
 
Irefin      0.45       0.95     1.42 
 
Gege     0.30       1.00     2.03 
 
Gbagi    0.44       0.92     0.50  
 
Odinjo   0.73       2.43     0.60  
 
Omi Adio   0.47       0.98     0.66 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Table 4.2: Sorensen’s coefficient of similarity for streams’ earthworms 
Sites  Awba stream    Irefin    Gege    Gbagi    Odinjo    Omi Adio 
 
Awba stream                              0.86     0.67       0.86        0.67        0.86 
 
Irefin                                0.8          1            0.8            1 
 
Gege                                                0.8         0.8            1 
 
Gbagi                                                              0.8     1 
 
Odinjo                                                                            0.8 
 
Omi Adio   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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site (Balewa) (1.00), followed by the Oremeji dumpsite (0.99), Idi Ope (0.96), Olodo 
(0.93), Moniya (0.84), and the least was observed at the Ojokondo dumpsite (0.80) 
(Table 4.3). 
Maximum species richness in terms of Menhinick’s index was recorded at Ojokondo 
(0.75), followed by Oremeji (0.64), Olodo (0.63) and Idi Ope (0.49). The control site 
(Balewa) and Moniya were equally the same and they had the minimum values (0.37) 
(Table 4.3). 
The Sorensen’s coefficient of community similarity showed that the sites were closely 
similar in terms of earthworms’ composition (Table 4.4). 
 
4.4 Result of analysis of stream water samples  
4.4.1 Bimonthly variation of physico-chemical characteristics of stream water 
samples  
The range and mean values of the physico-chemical characteristics of stream water 
samples are shown in Appendix 5. Details are shown in Appendices 9 to 19.  
 
4.4.1.1 Hydrogen ion concentration (pH) 
The bimonthly values of pH of the stream water samples ranged from 6.24 to 8.38 
(7.06±0.21) at Irefin upstream, 6.52 to 7.23 (6.75±0.07) at Gege upstream, 6.27 to 
7.86 (6.94±0.14) at Gbagi upstream, 6.28 to 8.26 (6.98±0.14) at Odinjo upstream, 
6.23 to 8.12 (7.06±0.16) at Omi Adio upstream, and 6.60 to 9.00 (7.34±0.22) at the 
control site (Awba stream) (Figure 4.3a; Appendix 5). It ranged from 6.38 to 7.99 
(6.84±0.12) at Irefin downstream, 6.32 to 8.18 (7.15±0.18) at Gege downstream, 6.27 
to 8.20 (7.00±0.17) at Gbagi downstream, 6.48 to 8.33 (7.07±0.14) at Odinjo 
downstream, 5.48 to 7.60 (6.87±0.17) at Omi Adio downstream (Figure 4.3b; 
Appendix 5).  
One way analysis of variance showed that the pH of the samples were not 
significantly different from one another at P<0.05 (Appendix 7). However, Duncan’s 
multiple range test showed that the pH of Gege upstream was significantly different 
from that of the control site (Awba stream) but the two were not significantly different 
from those of the other stream samples at P<0.05 (Appendix 8). 
 
 
 
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Table 4.3: Diversity indices of earthworms observed at the dumpsites  
Sites    Shannon             Shannon’s  Menheinick’s 
    Weiner   Evenness   Species Richness 
 
 
 
Balewa        0.52       1.00    0.37 
 
Ojokondo     0.38       0.80    0.75 
 
Olodo     0.49       0.93    0.63 
 
Moniya   0.27       0.84     0.37  
 
Idi Ope   0.37       0.96     0.49  
 
Oremeji   0.50       0.99     0.64 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Table 4.4: Sorensen’s coefficient of similarity for dumpsites’ earthworms 
Sites  Balewa    Ojokondo    Olodo    Moniya    Idi Ope    Oremeji 
 
Balewa                                   1      1            0.8            0.8             1 
 
Ojokondo                     1           0.8             0.8             1 
 
Olodo                                              0.8           0.8             0.8 
 
Moniya                                                    0.8       0.8 
 
Idi Ope                                                                                 0.8 
 
Oremeji   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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10.00 Upstream Irefin Upstream 
NL 
8.00 Gege Upstream 
NL Gbagi Upstream 6.00 
Odinjo Upstream 
4.00 
Omi Adio 
2.00 Upstream 
Awba stream 
0.00 
10.00 
Downstream NL - NESREA 
9.00 NL LIMIT (6.5 - 8.5) 
8.00 
7.00 NL 
6.00 
5.00 Irefin Downstream  
4.00 
3.00 Gege Downstream 
2.00 
1.00 Gbagi Downstream 
0.00 
Odinjo Downstream 
Omi Adio 
Downstream 
Awba stream 
Sampling Year/Month  
Figure 4.3: Bimonthly variation of pH values of streams                                     
(a) Upstream  (b) Downstream 
 
 
pH pH 
UNIVERSITY OF IBADAN LIBRARY
 
4.4.1.2 Dissolved oxygen (DO) 
During the sampling period, dissolved oxygen was not detected (0 mg/L) in the 
samples from the Irefin upstream in the months of March and July 2008, March to 
November 2009 and January 2010. Samples obtained from the Irefin downstream had 
no dissolved oxygen content in March, May, July and November 2008; January, May, 
July, September and November 2009; and January 2010. Samples obtained from the 
Gege upstream had no dissolved oxygen content in May and November 2008; 
January, May to November 2009; and January 2010.Gege downstream had no 
dissolved oxygen content in the sampled months except in March 2008 with a value 
of 2.24 mg/L. Gbagi upstream had no dissolved oxygen content in the samples 
obtained from July and September 2008; May, July, September and November 2009; 
and January 2010. At Gbagi downstream, it was not detected in July 2008; May, July 
September and November 2009; and January 2010. At the Odinjo upstream, dissolved 
oxygen was not detected in May 2008, January to September 2009 and January 2010. 
At Odinjo downstream, it was not detected in May and November 2008; March to 
November 2009; and January 2010. Samples collected from the Omi Adio upstream 
had no dissolved oxygen in May, July and September 2009. At the Omi Adio 
downstream, it was not detected in March, May, July and September 2009. The 
control site (Awba stream) had no dissolved oxygen content in July 2008 and May to 
November 2009 (Figure 4.4; Appendices 9 to 19). 
However, the dissolved oxygen contents observed during the sampling period ranged 
from 1.22 to 2.13 mg/L (1.69±0.13 mg/L) at the Irefin upstream, 0.81 to 3.30 mg/L 
(2.05±0.48 mg/L) at the Gege upstream, 0.46 to 3.55 mg/L (1.89±0.43 mg/L) at the 
Gbagi upstream, 0.61 to 4.01 mg/L (2.05±0.57 mg/L) at Odinjo upstream, 0.20 to 
5.89 mg/L (2.09±0.50 mg/L) at Omi Adio upstream, and 3.96 to 5.98 mg/L 
(5.31±0.17 mg/L) at the control site (Awba stream) (Figure 4.4a; Appendix 5). It 
ranged from 1.52 to 1.98 mg/L (1.75±0.23 mg/L) at the Irefin downstream, 1.50 to 
2.24 mg/L (1.87±0.37 mg/L) at the Gege downstream, 1.68 to 4.67 mg/L (2.53±0.42 
mg/L) at the Gbagi downstream, 1.07 to 3.86 mg/L (2.29±0.51 mg/L) at Odinjo 
downstream and 0.25 to 4.78 mg/L (1.74±0.47 mg/L) at the Omi Adio downstream 
(Figure 4.4b; Appendix 5).  
One way analysis of variance showed significant differences of the dissolved oxygen 
of the streams at P<0.05 (Appendix 7). Duncan’s multiple range test showed that the 
 
 
UNIVERSITY OF IBADAN LIBRARY
 
dissolved oxygen of the control site (Awba stream) was significantly different from 
those of all the other stream samples at P<0.05 (Appendix 8).  
 
4.4.1.3 Biochemical oxygen demand (BOD) 
The bimonthly values of biochemical oxygen demand (BOD) of the stream water 
samples ranged from 26.39 to 138.12 mg/L (84.27±8.97 mg/L) at Irefin upstream, 
18.43 to 147.03 mg/L (96.72±13.03 mg/L) at Gege upstream, 30.72 to 126.88 mg/L 
(89.84±9.48 mg/L) at Gbagi upstream, and 39.20 to 103.79 mg/L (66.57±7.07 mg/L) 
at Odinjo upstream and 21.45 to 105.34 mg/L (55.46±8.82 mg/L) at Omi Adio 
upstream (Figure 4.5a; Appendix 5). It ranged from 28.31 to 146.03 mg/L 
(93.37±11.83 mg/L) at Irefin downstream, 21.0 to 160.66 mg/L (104.51±14.01 mg/L) 
at Gege downstream, 23.25 to 141.21 mg/L (90.46±10.96 mg/L) at Gbagi 
downstream, 41.66 to 112.39 mg/L (72.21±7.16 mg/L) at Odinjo downstream, 13.36 
to 92.60 mg/L (46.70±7.88 mg/L) at Omi Adio downstream and 9.48 to 85.71 mg/L 
(44.98±7.18 mg/L) at the control site (Awba stream) (Figure 4.5b; Appendix 5). 
One way analysis of variance showed significant differences of the biochemical 
oxygen demand (BOD) of the stream samples at P<0.05 (Appendix 7). Duncan’s 
multiple range test showed that the biochemical oxygen demand (BOD) content of the 
control site (Awba stream) was not significantly different from those of the upstream 
and downstream of Omi Adio and Odinjo but they were significantly different from 
the other samples at P<0.05 (Appendix 8).  
 
4.4.1.4 Chemical oxygen demand (COD) 
The bimonthly values of the chemical oxygen demand (COD) of stream water 
samples ranged from 146.53 to 480.00 mg/L (315.47±28.51 mg/L) at Irefin upstream, 
188.69 to 600 mg/L (396.81±37.96 mg/L) at Gege upstream, 130.68 to 500.00 mg/L 
(338.42±29.68 mg/L) at Gbagi upstream, 118.64 to 520.00 mg/L (260.06±34.62 
mg/L) at Odinjo upstream, 50.00 to 328.02 mg/L (191.51±28.73 mg/L) at Omi Adio 
upstream and 28.86 to 272.13 mg/L (143.43±22.42 mg/L) at the control site (Awba 
stream) (Figure 4.6a; Appendix 5). It ranged from 142.87 to 487.10 mg/L 
(361.97±34.13 mg/L) at Gege downstream, 166.52 to 540.00 mg/L (343.74±34.21 
mg/L) at Irefin downstream, 132.81 to 540.00 mg/L (382.09±31.59 mg/L) at Gbagi  
 
 
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` Upstream 
8.00 
6.00 
4.00 NL 
Irefin Upstream 
2.00 Gege Upstream 
Gbagi Upstream 
0.00 Odinjo Upstream 
Omi Adio Upstream 
Downstream 
-2.00 Awba stream 
8.00 
7.00 
6.00 
5.00 
4.00 NL 
3.00 
2.00 Irefin Downstream  
1.00 Gege Downstream 
0.00 Gbagi Downstream 
-1.00 Odinjo Downstream 
-2.00 Omi Adio Downstream 
Awba stream 
    NL - NESREA LIMIT (4.0 mg/L) 
Sampling Year/Month  
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that dissolved oxygen was not detected in the samples. 
 
Figure 4.4: Bimonthly variation of dissolved oxygen (DO) values of streams  
                                     (a) Upstream  (b) Downstream 
 
 80 
DO (mg/L) DO (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
160 
140 
Upstream Irefin Upstream 
120 
Gege Upstream 
100 
Gbagi Upstream 
80 
Odinjo Upstream 
60 
Omi Adio Upstream 
40 
Awba stream 
20 
NL 
0 
160 Downstream Irefin Downstream  
140 
Gege Downstream 
120 
100 Gbagi Downstream 
80 Odinjo Downstream 
60 Omi Adio Downstream 
40 Awba stream 
20 
0 NL 
NL - NESREA LIMIT (6.0 mg/L) 
Sampling Year/Month 
    
 
Figure 4.5: Bimonthly variation of biochemical oxygen demand (BOD) values of streams  
                                     (a) Upstream  (b) Downstream
 81 
 
BOD (mg/L) BOD (mg/L) UNIVERSITY OF IBADAN LIBRARY
 
downstream, 121.88 to 480.00 mg/L (274.57±29.43 mg/L) at Odinjo downstream and 
43.08 to 315.67 mg/L (154.69±25.96 mg/L) at Omi Adio downstream (Figure 4.6b; 
Appendix 5). 
One way analysis of variance showed significant differences of the chemical oxygen 
demand (COD) of the streams at P<0.05 (Appendix 7). Duncan’s multiple range test 
showed that the chemical oxygen demand (COD) of the control site (Awba stream) 
was not significantly different from those of the upstream and downstream of Omi 
Adio but they were significantly different from the other samples at P<0.05 
(Appendix 8). 
 
4.4.1.5 Total dissolved solids (TDS) 
The bimonthly values of total dissolved solids (TDS) of the stream water samples 
ranged from 363.00 to 1630.00 mg/L (810.17±114.96 mg/L) at Irefin upstream, 
552.00 to 2640.00 mg/L (1161.08±161.97 mg/L) at Gege upstream, 52.5 to 492.00 
mg/L (281.98±35.32 mg/L) at Gbagi upstream, 159.00 to 1350.00 mg/L 
(865.00±112.88 mg/L) at Odinjo upstream, 29.20 to 262.00 mg/L (171.93±20.82 
mg/L) at Omi Adio upstream and 42.10 to 255.00 mg/L (154.01±18.93 mg/L) at the 
control site (Awba stream) (Figure 4.7a; Appendix 5). It ranged from 555.00 to 
1792.00 mg/L (904.75±101.30 mg/L) at Irefin downstream, 847.00 to 2847.00 mg/L 
(1344.00±158.99 mg/L) at Gege downstream, 60.60 to 513.00 mg/L (297.88±30.15 
mg/L) at Gbagi downstream, 264.00 to 1600.00 mg/L (862.17±121.95 mg/L) at 
Odinjo downstream and 77.10 to 621.00 mg/L (254.15±47.75 mg/L) at Omi Adio 
downstream, (Figure 4.7b; Appendix 5). 
One way analysis of variance showed that some of the streams’ total dissolved solids 
(TDS) were significantly different at P<0.05 (Appendix 7). Duncan’s multiple range 
test showed that the upstream and downstream of Gege were not significantly 
different from each other but they were significantly different from all other stream 
samples at P<0.05 (Appendix 8). 
 
4.4.1.6 Electrical conductivity (EC) 
The bimonthly values of electrical conductivity (EC) of the stream water samples 
ranged from 606.00 to 3056.00 µS/cm (1532.17±219.85 µS/cm) at Irefin upstream, 
920.00 to 4690.00 µS/cm (2119.50±286.61 µS/cm) at Gege upstream, 105.00 to  
 
 82 
UNIVERSITY OF IBADAN LIBRARY
 
700 Upstream 
600 
Irefin Upstream 
500 Gege Upstream 
400 Gbagi Upstream 
300 Odinjo Upstream 
200 Omi Adio Upstream 
Awba stream 
100 
NL 
0 
700 Downstream Irefin Downstream  
600 Gege Downstream 
Gbagi Downstream 
500 
Odinjo Downstream 
400 Omi Adio Downstream 
300 Awba stream 
200 
100 
NL 
0 
NL - NESREA LIMIT (30 mg/L)                                                                                                       
Sampling Year/Month 
                     
Figure 4.6: Bimonthly variation of chemical oxygen demand (COD) values of streams                                    
     (a) Upstream  (b) Downstream 
 
83 
 
COD (mg/L) COD (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
3000 Irefin Upstream 
Upstream 
Gege Upstream 
2500 
Gbagi Upstream 
2000 Odinjo Upstream 
Omi Adio Upstream 
1500 Awba stream 
1000 WHO 
500 
0  
Downstream 
3000 
(WHO Limit - 1000 mg/L) 
2500 
2000 
1500 
1000 WHO 
500 
0 Irefin Downstream  
Gege Downstream 
Gbagi Downstream 
Odinjo Downstream 
Omi Adio Downstream 
Sampling Year/Month Awba stream 
  
Figure 4.7: Bimonthly variation of total dissolved solids (TDS) values of streams 
  (a) Upstream                                 (b) Downstream 
 
 
 
 
TDS (mg/L) TDS (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
984.00 µS/cm (532.79±65.31 µS/cm) at Gbagi upstream, 265.00 to 2530.00 µS/cm 
(1585.50±210.73 µS/cm) at Odinjo upstream, 48.80 to 688.00 µS/cm (328.73±47.93 
µS/cm) at Omi Adio upstream and 70.30 to 426.00 µS/cm (275.03±32.39 µS/cm) at 
the control site (Awba stream) (Figure 4.8a; Appendix 5). It ranged from 935.00 to 
3584.00 µS/cm (1647.58±198.87 µS/cm) at Irefin downstream, 1684.00 to 5694.00 
µS/cm (2518.50±323.32 mg/L) at Gege downstream, 100.90 to 1026.00 µS/cm 
(561.99±61.88µS/cm) at Gbagi downstream, 440.00 to 4728.00 µS/cm 
(1737.17±347.66 µS/cm) at Odinjo downstream and 128.60 to 1240.00 µS/cm 
(497.41±104.25 µS/cm) at Omi Adio downstream (Figure 4.8b; Appendix 5). 
One way analysis of variance showed significant differences of the electrical 
conductivity of the streams at P<0.05 (Appendix 7). Duncan’s multiple range test 
showed the same trend with those of total dissolved solids contents of the samples 
P<0.05 (Appendix 8). 
 
4.4.1.7 Total alkalinity 
The bimonthly values of total alkalinity of the stream water samples ranged from 
205.20 to 836.55 mg/L (546.02±56.67 mg/L) at Irefin upstream, 266.40 to 1487.50 
mg/L (741.19±99.12 mg/L) at Gege upstream, 3.56 to 524.02 mg/L (277.04±42.94 
mg/L) at Gbagi upstream, 230.40 to 902.70 mg/L (518.72±66.96 mg/L) at Odinjo 
upstream, 101.32 to 336.30 mg/L (201.41±20.31 mg/L) at Omi Adio upstream and 
98.00 to 430.70 mg/L (188.93±31.19 mg/L) at the control site (Awba stream) (Figure 
4.9a; Appendix 5). It ranged from 327.60 to 926.36 mg/L (594.57±55.32 mg/L) at 
Irefin downstream, 374.92 to 1497.39 mg/L (795.98±91.21 mg/L) at Gege 
downstream, 99.98 to 452.60 mg/L (284.89±31.52 mg/L) at Gbagi downstream, 
151.90 to 1052.87 mg/L (416.75±76.50 mg/L) at Odinjo downstream and 89.64 to 
424.15 mg/L (249.72±32.80 mg/L) at Omi Adio downstream (Figure 4.9b; Appendix 
5). 
One way analysis of variance showed that some of the total alkalinity contents of the 
streams were significantly different at P<0.05 (Appendix 7). Duncan’s multiple range 
test showed that the upstream  and downstream of Gege were not significantly 
different from each other but they were significantly different from all other stream 
samples at P<0.05 (Appendix 8). 
 
 
 
UNIVERSITY OF IBADAN LIBRARY
 
6000 
Upstream 
5000 Irefin Upstream 
4000 Gege Upstream 
Gbagi Upstream 
3000 
Odinjo Upstream 
2000 Omi Adio Upstream 
1000 Awba stream 
0 
ZSZSWCXX
6000 Downstream 
5000 
4000 
Irefin Downstream  
3000 
Gege Downstream 
2000 
Gbagi Downstream 
1000 
Odinjo Downstream 
0 
Omi Adio Downstream 
Awba stream 
Sampling Year/Month  
 
Figure 4.8: Bimonthly variation of electrical conductivity (EC) values of streams  
                                       (a) Upstream  (b) Downstream 
 
 
U EC (µS/cm) EC(µS/cm) NIVERSITY OF IBADAN LIBRARY
 
1600 
Upstream 
1400 
Irefin Upstream 
1200 
Gege Upstream 
1000 
Gbagi Upstream 
800 
Odinjo Upstream 
600 
Omi Adio Upstream 
400 
Awba stream 
200 
0 
1600 
Downstream 
1400 
1200 Irefin Downstream  
1000 
800 Gege Downstream 
600 
400 Gbagi Downstream 
200 
Odinjo Downstream 
0 
Omi Adio 
Downstream 
Awba stream 
Sampling Year/Month  
Figure 4.9: Bimonthly variation of total alkalinity values of streams 
                                       (a) Upstream  (b) Downstream 
87 
 
 
T. Alk (mg/L) T. ALK (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
4.4.2 Bimonthly variation of anions of stream water samples 
The range and mean values of the anions of the stream water samples are shown in 
Appendix 5. Details are shown in Appendices 9 to 19. 
 
4.4.2.1 Chloride 
The bimonthly values of chloride contents of the stream water samples ranged from 
76.50 to 391.33 mg/L (200.58±29.77 mg/L) at Irefin upstream, 68.81 to 658.94 mg/L 
(280.57±45.27 mg/L) at Gege upstream, 24.53 to 89.76 mg/L (47.95±4.40 mg/L) at 
Gbagi upstream, 24.99 to 374.79 mg/L (228.34±31.74 mg/L) at Odinjo upstream, 
21.34 to 97.10 mg/L (45.70±6.83 mg/L) at Omi Adio downstream and 13.63 to 47.08 
mg/L (29.18±2.89 mg/L) at the control site (Awba stream) (Figure 4.10a; Appendix 
5). It ranged from 62.21 to 385.45 mg/L (199.48±25.24 mg/L) at Irefin downstream, 
110.09 to 527.40 mg/L (280.59±42.24 mg/L) at Gege downstream, 36.58 to 94.16 
mg/L (52.45±4.30 mg/L) at Gbagi downstream, 42.93 to 270.54 mg/L (155.49±17.03 
mg/L) at Odinjo downstream and 8.69 to 94.16 mg/L (35.67±7.08 mg/L) at Omi Adio 
upstream (Figure 4.10b; Appendix 5). 
One way analysis of variance showed significant differences of some of the chloride 
contents of the streams at P<0.05 (Appendix 7). Duncan’s multiple range test also 
showed further significant differences (Appendix 8). 
 
4.4.2.2 Phosphate – phosphorus 
During the sampling period, phosphate – phosphorus was not detected at Gbagi 
upstream and downstream in the months of July and September 2008, 2009 March, 
July and November. In the month of July 2008, it was not detected at the Omi Adio 
downstream while in May 2009, it was not detected at its upstream. In 2009 March, 
July and November and so also January 2010, it was not detected at both upstream 
and downstream of Omi Adio. At the upstream of Odinjo, phosphate - phosphorus 
was not detected in March 2009, May 2009 and January 2010, while at its 
downstream, it was not detected in July 2009. It was not detected at the control site 
(Awba stream) in the months of July 2008, May, July and November 2009 and also 
January 2010 (Figure 4.11; Appendices 9 to 19). 
However, the ranges observed in the months detected were from 180.95 to 1265.31 
(542.03±103.67 mg/L) at the Irefin upstream, 146.94 to 2751.02 mg/L  
 
 
UNIVERSITY OF IBADAN LIBRARY
 
700 
Upstream 
600 
500 
400 
NL 
300 Irefin Upstream 
200 Gege Upstream 
100 Gbagi Upstream 
Odinjo Upstream 
0 
Omi Adio Upstream 
-100 
Awba stream 
700  NL - NESREA Limit (350 mg/L) 
600 Downstream 
500 
400 
NL 
300 
Irefin Downstream  
200 
Gege Downstream 
100 Gbagi Downstream 
0 Odinjo Downstream 
Omi Adio Downstream 
Awba stream 
 
Figure 4.10: Bimonthly variation of chloride values of streams 
(a) Upstream  (b) Downstream 
 
 
Cl- (mg/L) Cl- (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
(1736.66±226.29 mg/L) at the Gege upstream, 60.57 to 269.39 mg/L (181.82±29.37 
mg/L) at the Gbagi upstream, 20.41 to 885.71 mg/L (246.30±93.12 mg/L) at the 
Odinjo upstream, 76.19 to 220.41 mg/L (134.35±21.00 mg/L) at the Omi Adio 
upstream and 8.16 to 240.82 mg/L (93.60±42.37 mg/L) at the control site (Awba 
stream) (Figure 4.11a; Appendix 5). It ranged from 11.43 to 1526.53 mg/L 
(563.99±144.61 mg/L) at the Irefin downstream, 557.14 to 2485.32 mg/L 
(1460.38±161.51 mg/L) at the Gege downstream, 80.95 to 383.67 mg/L 
(243.86±42.35 mg/L) at the Gbagi downstream, 14.29 to 892.35 mg/L (191.30±76.28 
mg/L) at the Odinjo downstream and 81.63 to 605.71 mg/L (209.05±67.75 mg/L) at 
the Omi Adio downstream (Figure 4.11b; Appendix 5). 
One way analysis of variance showed that some of the phosphate – phosphorus 
contents of the streams were significantly different at P<0.05 (Appendix 7). Duncan’s 
multiple range test showed that the upstream and downstream of Gege were not 
significantly different from each other but they were significantly different from all 
other stream samples at P<0.05 (Appendix 8). 
 
4.4.2.3 Nitrate – nitrogen 
Nitrate – nitrogen was not detected at the control site (Awba stream) in March 2009, 
September 2009, November 2009 and January 2010. It was not also detected at Gege 
upstream in May 2008, March 2009, May 2009 and September 2009. At the 
downstream of Gege, nitrate-nitrogen was not detected in March and July, September 
and November 2009 and also January 2010. At both upstream and downstream of 
Irefin, nitrate-nitrogen was not detected September 2008, throughout sampling 
months of 2009 and January 2010. However, it was detected at the upstream in March 
2009 with the value of 4.04 mg/L. At Gbagi upstream, nitrate-nitrogen was not 
detected in July 2009 and September 2009, at its downstream, nitrate-nitrogen was not 
detected in September 2008, July 2009, September 2009, November 2009 and January 
2010. At Omi Adio upstream and downstream, it was not detected throughout the 
sampling months of 2009 and January 2010, except at the downstream in March 2009 
with a value of 2.86 mg/L, and also at the upstream in May 2009, with a value of 3.65 
mg/L. At the upstream of Odinjo, it was not detected in May 2008, July, September 
and November 2009. At the downstream of Odinjo, it was not detected in March, 
September and November 2009 (Figure 4.12; Appendices 9 to 19).  
 
 
UNIVERSITY OF IBADAN LIBRARY
 
Upstream 
3000 Irefin Upstream 
Gege Upstream 
2500 Gbagi Upstream 
2000 Odinjo Upstream 
Omi Adio Upstream 
1500 
Awba stream 
1000 
500 
0 NL 
-500 
 Downstream 
3000 Irefin Downstream  
2500 Gege Downstream 
2000 Gbagi Downstream 
Odinjo Downstream 
1500 
Omi Adio Downstream 
1000 Awba stream 
500 
0 NL 
-500 
NL - NESREA LIMIT (3.5 mg/L) 
Sampling Year/Month 
 
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that phosphate-phosphorus was not detected in the samples.  
Figure 4.11: Bimonthly variation of phosphate values of streams 
(a) Upstream  (b) Downstream 
 
 
Phosphate (mg/L) Phosphate (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
However, the bimonthly values of nitrate-nitrogen detected in the stream water 
samples ranged from 1.58 to 8.06 mg/L (5.08±0.91 mg/L) at Irefin upstream, 0.16 to 
12.62 mg/L (4.94±1.43 mg/L) at the Gege upstream, 0.38 to 18.92 mg/L (7.31±1.87 
mg/L) at Gbagi upstream, 0.36 to 17.90 mg/L (7.24±1.92 mg/L) at Odinjo upstream 
and 0.45 to 6.21 mg/L (3.18±0.88 mg/L) at Omi Adio upstream and 0.04 to 8.36 mg/L 
(4.40±1.33 mg/L) at the control site, (Awba stream) (Figure 4.12a; Appendix 5). It 
ranged from 1.19 to 7.39 mg/L (5.17±1.03 mg/L) at Irefin downstream, 0.57 to 12.05 
mg/L (4.70±1.42 mg/L) at the Gege downstream, 0.57 to 21.64 mg/L (6.75±2.33 
mg/L) at Gbagi downstream, 0.04 to 14.80 mg/L (5.95±1.74 mg/L) at Odinjo 
downstream and 2.29 to 5.54 mg/L (3.64±0.48 mg/L) at Omi Adio downstream 
(Figure 4.12a; Appendix 5). 
One way analysis of variance showed that the nitrate-nitrogen content of the stream 
samples were not significantly different from one another at P<0.05 (Appendices 6 
and 7). 
 
4.4.2.4  Sulphate - sulphur  
The bimonthly values of sulphate-sulphur contents of the stream water samples 
ranged from 570.45 to 4850.00 mg/L (1913.93±433.37 mg/L) at Irefin upstream, 
1066.67 to 6481.25 mg/L (3469.28±633.38 mg/L) at Gege upstream, 254.55 to 
2731.25 mg/L (804.20±392.53 mg/L) at Gbagi upstream, 475.00 to 1795.45 mg/L 
(1207.88±139.40 mg/L) at Odinjo upstream, 233.33 to 3050.00 mg/L (816.73±271.27 
mg/L) at Omi Adio upstream and 133.33 to 5550.00 mg/L (1582.58±496.21 mg/L) at 
the control site (Awba stream) (Figure 4.13a; Appendix 7). It ranged from 418.18 to 
4487.50 mg/L (2307.28±390.26) at Irefin downstream, 612.50 to 14068.75 mg/L 
(4460.84±1492.60 mg/L) at Gege downstream, 100.00 to 1931.25 mg/L 
(774.56±207.09 mg/L) at Gbagi downstream, 200.00 to 2968.75 mg/L 
(1044.63±265.40 mg/L) at Odinjo downstream and 21.34 to 3050.00 mg/L 
(986.73±355.72 mg/L) at Omi Adio downstream; In November 2009, sulphate-
sulphur was not detected at the downstream of Omi Adio (Figure 4.13b; Appendix 5). 
One way analysis of variance showed that some of the streams’ sulphate - sulphur 
were significantly different at P<0.05 (Appendix 7). Duncan’s multiple range test 
showed that the sulphate - sulphur of the upstream and downstream of Gege were not 
significantly different from each other but they were significantly different from all 
 
 
UNIVERSITY OF IBADAN LIBRARY
 
45 Upstream 
40   NL 
35 Irefin Upstream 
30 Gege Upstream 
25 Gbagi Upstream 
20 
15 Odinjo Upstream 
10 Omi Adio Upstream 
5 Awba stream 
0 
-5 
45 Downstream 
40 NL 
35 Irefin Downstream  
30 Gege Downstream 
25 Gbagi Downstream 
20 
15 Odinjo Downstream 
10 Omi Adio Downstream 
5 Awba stream 
0 
-5 
NL - NESREA LIMIT (40 mg/L) 
Sampling Year/Month  
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that nitrate-nitrogen was not detected in the samples.  
 
Figure 4.12: Bimonthly variation of nitrate values of streams 
                                      (a) Upstream  (b) Downstream 
 
 
Nitrate (mg/L) Nitrate (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
other stream samples except that the Gege upstream was not significantly different 
from Irefin upstream and downstream at P<0.05 (Appendix 8). 
 
4.4.3 Bimonthly variation of cations of stream water samples 
The range and mean values of the cations of stream water samples are shown in 
Appendix 6. Details are shown in Appendices 9 to 19. 
 
4.4.3.1 Calcium 
The bimonthly values of calcium contents of the stream water samples ranged from 
10.89 to 129.99 mg/L (73.83±15.31 mg/L) at Irefin upstream, 38.89 to 82.67 mg/L 
(60.81±5.48 mg/L) at Gege upstream, 58.99 mg/L (42.85±6.28 mg/L) at Gbagi 
upstream, 8.57 to 72.09 mg/L (35.09±11.37 mg/L) at Odinjo upstream, 8.69 to 29.57 
mg/L (18.98±3.74 mg/L) at Omi Adio upstream and 24.72 to 55.50 mg/L (32.60±5.82 
mg/L) at the control site (Awba stream) (Figure 4.14a; Appendix 6). It ranged from 
11.83 to 82.91 mg/L (56.25±9.54) at Irefin downstream, 61.15 to 126.34 mg/L 
(78.84±10.28 mg/L) at Gege downstream, 31.10 to 36.73 to 62.93 mg/L (47.47±4.36 
mg/L) at Gbagi downstream, 0.92 to 101.31 mg/L (50.75±11.02 mg/L) at Odinjo 
downstream and 14.01 to 44.73 mg/L (30.62±4.18 mg/L) at Omi Adio downstream 
(Figure 4.14b; Appendix 6). 
Calcium was not detected at Gbagi upstream in the months of March, May, July and 
September 2008; January, May and November 2009; and January 2010. Throughout 
the sampling months of 2008, January 2009 and May 2009, calcium was not detected 
at Gbagi downstream. In March, July, September and November 2008; May 2009 and 
January 2010, calcium was not detected at Omi Adio upstream. In July, September 
and November 2008 and March 2009, it was not detected at Omi Adio downstream. 
At the Odinjo upstream, calcium was not detected in July, September and November 
2008; March and July 2009; and January 2009. At the Odinjo downstream, it was not 
detected in July, September and November 2008 and May 2009; and January 2010. 
Throughout the sampling months of 2008 and in January 2009, calcium was not 
detected at the control site (Awba stream) (Figure 4.14; Appendices 9 to 19). 
One way analysis of variance showed significant differences of the calcium contents 
of the streams at P<0.05 (Appendix 7). Duncan’s multiple range test also showed 
further significant differences (Appendix 8). 
 
 
UNIVERSITY OF IBADAN LIBRARY
 
16000 Irefin Upstream 
14000 Upstream 
Gege Upstream 
12000 
10000 Gbagi Upstream 
8000 Odinjo Upstream 
6000 Omi Adio Upstream 
4000 
2000 Awba stream 
0 NL 
-2000 
16000 Irefin Downstream  
14000 Downstream Gege Downstream 
12000 Gbagi Downstream 
10000 Odinjo Downstream 
8000 
Omi Adio Downstream 
6000 
Awba stream 
4000 
2000 
0 NL 
-2000 
Sampling Year/Month NL - NESREA LIMIT (500 mg/L) 
 
Figure 4.13: Bimonthly variation of sulphate values of streams  
                                   (a) Upstream  (b) Downstream 
 
 
Sulphate (mg/L) Sulphate (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
200 Upstream 
NL 
150 Irefin Upstream 
Gege Upstream 
100 
Gbagi Upstream 
Odinjo Upstream 
50 
Omi Adio Upstream 
0 Awba stream 
-50 
Downstream  
200 
NL 
150 Irefin Downstream  
100 Gege Downstream 
Gbagi Downstream 
50 Odinjo Downstream 
0 Omi Adio Downstream 
Awba stream 
-50 
NL - NESREA LIMIT (180 mg/L) 
Sampling Year/Month  
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that calcium was not detected in the samples.  
 
 
Figure 4.14: Bimonthly variation of calcium values of streams 
                                        (a) Upstream  (b) Downstream 
 
 
Ca (mg/L) 
Ca (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
4.4.3.2 Magnesium 
The bimonthly values of magnesium contents of the stream water samples ranged 
from 5.53 to 40.72 mg/L (27.57±3.72 mg/L) at Irefin upstream, 4.87 to 38.42 mg/L 
(23.88±3.61 mg/L) at Gege upstream, 8.25 to 38.27 mg/L (19.39±4.96 mg/L) at 
Gbagi upstream, 5.96 to 38.33 mg/L (19.18±3.95  mg/L) at Odinjo upstream, 7.49 to 
49.96 mg/L (21.50±4.46 mg/L) at Omi Adio upstream and 8.14 to 35.30 mg/L 
(18.25±4.22 mg/L) at the control site (Awba stream) (Figure 4.15a; Appendix 6). It 
ranged from 9.53 to 36.93 mg/L (26.55±2.88) at Irefin downstream, 20.45 to 58.29 
mg/L (31.52±4.47 mg/L) at Gege downstream, 6.48 to 36.84 mg/L (18.01±3.81 mg/L) 
at Gbagi downstream, 4.44 to 38.53 mg/L (20.85±3.86 mg/L) at Odinjo downstream 
and 9.21 to 36.09 mg/L (19.85±3.33 mg/L) at Omi Adio downstream (Figure 4.15b; 
Appendix 6). 
One way analysis of variance showed that the magnesium of the stream samples were 
not significantly different at P<0.05 (Appendix 7). However, Duncan’s multiple range 
test showed that Gege downstream was significantly different from the Gbagi 
downstream and control site, but it was not different from the others at P<0.05 
(Appendix 8). 
 
4.4.4 Bimonthly variation of trace and heavy metals of stream water samples 
The range and mean values of the trace and heavy metals of stream water samples are 
shown in Appendix 6. Details are shown in Appendices 9 to 19. 
 
4.4.4.1 Iron 
In May 2008, iron was not detected in the samples from the Irefin downstream, Gege 
downstream, Gbagi upstream and downstream, Odinjo downstream and Omi Adio 
downstream. In July 2008, iron was not detected in all sampling sites except the 
upstream and downstream of Odinjo. In September 2008, it was not detected at the 
Gege downstream, Gbagi upstream and Omi Adio upstream. In November 2008, iron 
was not detected at the Omi Adio upstream. In March 2009, it was not detected at the 
Omi Adio downstream and Odinjo upstream. In May 2009, iron was not detected at 
the Gege downstream, Gbagi upstream and downstream, Odinjo downstream and Omi 
Adio upstream.  In July 2009, it was not detected at the Odinjo upstream. In 
November 2009, iron was not detected at the Gege upstream, Gbagi upstream and the
 
 
UNIVERSITY OF IBADAN LIBRARY
 
70 
Upstream 
60 
50 
40 
NL 
30 Irefin Upstream 
Gege Upstream 
20 
Gbagi Upstream 
10 Odinjo Upstream 
Omi Adio Upstream 
0 Awba stream 
70 
Downstream 
60 
50 
40 NL 
30 
Irefin Downstream  
20 Gege Downstream 
10 Gbagi Downstream 
Odinjo Downstream 
0 
Omi Adio Downstream 
Awba stream 
NL - NESREA LIMIT (40 mg/L) 
Sampling Year/Month  
 
Figure 4.15: Bimonthly variation of magnesium values of streams  
                                   (a) Upstream  (b) Downstream
 
 
Mg (mg/L) Mg (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
control site, while in January 2010, it was not detected at the upstream of Gege, Gbagi 
and Odinjo (Figure 4.16; Appendix 9 to 19). 
The bimonthly values of iron ranged from 0.03 to 13.15 mg/L (4.76±1.50 mg/L) at the 
Irefin upstream, 0.37 to 11.51 mg/L (4.52±1.47 mg/L) at the Gege upstream, 0.27 to 
7.43 mg/L (2.78±1.11 mg/L) at the Gbagi upstream, 0.13 to 11.75 mg/L (3.20±1.48 
mg/L) at the Odinjo upstream, 0.34 to 7.52 mg/L (2.95±0.84 mg/L) at the Omi Adio 
upstream and 0.02 to 2.56 mg/L (1.09±0.33 mg/L) at the control site (Awba stream) 
(Figure 4.16a; Appendix 6). It ranged from 0.31 to 7.81 mg/L (3.37±0.88 mg/L) at the 
Irefin downstream, 0.21 to 9.80 mg/L (3.86±1.40 mg/L) at the Gege downstream, 
0.02 to 18.21 mg/L (4.18±1.91 mg/L) at the Gbagi downstream, 0.18 to 30.66 mg/L 
(7.15±3.10 mg/L) at the Odinjo downstream and 0.12 to 8.22 mg/L (2.69±0.90 mg/L) 
at the Omi Adio downstream (Figure 4.16b; Appendix 6). 
One way analysis of variance showed that the iron contents of the stream samples 
were not significantly different at P<0.05 (Appendix 7). However, Duncan’s multiple 
range test showed that the iron contents of the Odinjo downstream was significantly 
different from those of the control site (Awba stream) (Appendix 8). 
 
4.4.4.2 Manganese 
Manganese was not analysed in all the stream samples in the months of March, May 
and July 2008. It was not detected at the Gege upstream in the months of November 
2009 and January 2010, while at the Gege downstream it was not also detected in the 
months of Sept 2008 and May 2009. At Gbagi upstream, manganese was not detected 
in September 2008, January 2009, May 2009, November 2009 and January 2010. At 
Gbagi downstream, manganese was not detected in the months of November 2008 
and May 2009. In the months of March 2009, July 2009 and January 2010, 
manganese was not detected at the Odinjo upstream, while at the downstream, it was 
not detected in May 2009. In the months of March and May 2009, manganese was not 
detected at the downstream and upstream of Omi Adio respectively. At both 
November 2008 and 2009, it was not detected at the control site (Awba stream) 
(Figure 4.17; Appendices 9 to 19). 
The bimonthly values of manganese ranged from 0.07 to 2.50 mg/L (1.06±0.30 mg/L) 
at the Irefin upstream, 0.02 to 11.55 mg/L (2.22±1.57 mg/L) at the Gege upstream, 
0.21 to 3.17 mg/L (1.29±0.67 mg/L) at the Gbagi upstream, 0.0007 to 3.20 (1.25±0.47  
 
 
UNIVERSITY OF IBADAN LIBRARY
 
40 Upstream Irefin Upstream 
Gege Upstream 
30 
Gbagi Upstream 
Odinjo Upstream 
20 
Omi Adio Upstream 
10 Awba stream 
NL 
0 
-10 Downstream 
40 Irefin Downstream  
Gege Downstream 
30 Gbagi Downstream 
Odinjo Downstream 
20 
Omi Adio Downstream 
Awba stream 
10 
0 NL 
-10 
NL - NESREA LIMIT (0.5 mg/L) 
Sampling Year/Month 
  
 
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that iron was not detected in the samples.  
 
Figure 4.16: Bimonthly variation of iron values of streams  
                                   (a) Upstream  (b) Downstream 
 
 
Fe (mg/L) Fe (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
mg/L)  at the Odinjo upstream, 0.16 to 3.31 mg/L (1.15±0.39 mg/L) at the Omi Adio 
upstream and 0.02 to 1.36 mg/L (0.48±0.20 mg/L) at the control site (Awba stream) 
(Figure 4.17a; Appendix 6). It ranged from 0.06 to 1.67 mg/L (0.81±0.19 mg/L) at the 
Irefin downstream, 0.15 to 2.09 mg/L (0.99±0.25 mg/L) at the Gege downstream, 
0.07 to 1.88 mg/L (0.88±0.29 mg/L) at the Gbagi downstream, 0.13 to 3.04 mg/L 
(1.23±0.35 mg/L) at the Odinjo downstream and 0.11 to 10.13 mg/L (2.06±1.20 
mg/L) at the Omi Adio downstream (Figure 4.17b; Appendix 6). 
One way analysis of variance showed that manganese contents of the samples were 
not significantly different from one another (Appendices 6 and 7). 
 
4.4.4.3 Copper 
In the month of May 2008, copper was not detected at the Irefin downstream, Gege 
upstream and downstream, Gbagi upstream and downstream, Odinjo upstream and 
downstream, and Omi Adio downstream. In July 2008, it was not detected at the 
Irefin upstream and downstream, Gege downstream, Gbagi upstream and 
downstream, and Omi Adio upstream. In September 2008, it was not detected at the 
Gege downstream, Gbagi upstream and Odinjo upstream. In November 2008, it was 
not detected at the Omi Adio upstream and the control site (Awba stream). In March 
2009, copper was not detected at the Irefin downstream, Gbagi upstream and 
downstream, Odinjo upstream, Omi Adio upstream and downstream, and the control 
site (Awba stream). Copper was not detected in all samples in the months of May 009, 
July 2009, September 2009, November 2009 and January 2010 except at the Gege 
upstream, Gbagi downstream, Omi Adio downstream, Odinjo upstream and Irefin 
upstream respectively with values of 0.019 mg/L, 0.114 mg/L, 0.08 mg/L, 0.007 mg/L 
and 0.002 mg/L respectively (Figure 4.18; Appendices 9 to 19). 
One way analysis of variance showed that the copper contents of the streams were not 
significantly different from one another at P<0.05 (Appendices 6 and 7). 
 
4.4.4.4  Zinc 
During the sampling period, zinc was not detected at the downstream of Odinjo in 
March 2008. In the month of May 2008, it was not detected in all stream samples 
except at the upstream of Odinjo with a value of 0.0122 mg/L. In July 2008, it was not 
detected in all stream samples except at the Omi Adio upstream, Odinjo downstream  
 
 
UNIVERSITY OF IBADAN LIBRARY
 
Upstream 
12 
10 Irefin Upstream 
8 Gege Upstream 
6 Gbagi Upstream 
4 Odinjo Upstream 
2 Omi Adio Upstream 
0 Awba stream 
-2 
12 
10 
Downstream 
8 Irefin Downstream  
6 Gege Downstream 
4 
Gbagi Downstream 
2 
Odinjo Downstream 
0 
-2 Omi Adio Downstream 
Awba stream 
Sampling Year/Month  
 
NOTE: Manganese was not analysed in all the samples in March, May and July, 2008. All other blank spaces indicated that it 
was not detected. 
 
Figure 4.17: Bimonthly variation of manganese values of streams  
                                   (a) Upstream  (b) Downstream 
102 
 
 
Mn (mg/L) Mn (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
1.1 Irefin Upstream 
1 Upstream 
0.9 Gege Upstream 
0.8 
0.7 Gbagi Upstream 
0.6 
0.5 Odinjo Upstream 
0.4 Omi Adio Upstream 
0.3 
0.2 Awba stream 
0.1 
0 NL 
-0.1 
-0.2 
-0.3 
1.1 Irefin Downstream  
1 Downstream 
0.9 Gege Downstream 
0.8 
0.7 Gbagi Downstream 
0.6 Odinjo Downstream 
0.5 
0.4 Omi Adio Downstream 
0.3 
0.2 Awba stream 
0.1 
0 NL 
NL - NESREA LIMIT (0.01 mg/L) 
Sampling Year/Month  
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that copper was not detected in the samples.  
 
Figure 4.18: Bimonthly variation of copper values of streams  
                                   (a) Upstream  (b) Downstream
103 
 
 
Cu (mg/L) Cu (mg/L) UNIVERSITY OF IBADAN LIBRARY
 
and the control site (Awba stream). In September 2008, zinc was not detected at the 
Irefin downstream, Gege downstream, Gbagi upstream and Omi Adio upstream. In 
March 2009, it was not detected at the Gege downstream, Gbagi upstream and 
downstream, Odinjo downstream and Omi Adio upstream. In July 2009, zinc was not 
detected at the Irefin upstream, Gege downstream, and Odinjo upstream and 
downstream. In November 2009, it was not detected in all samples except at the Irefin 
upstream and downstream. In January 2010, it was not detected in all stream samples 
except at Gege downstream, Gbagi downstream, Omi Adio upstream and the control 
site (Awba stream) (Figure 4.19; Appendices 9 to 19). 
The bimonthly values of zinc ranged from 0.02 to 8.20 mg/L (1.77±1.06 mg/L) at the 
Irefin upstream, 0.002 to 1.71 mg/L (0.58±0.28 mg/L) at the Gege upstream, 0.002 to 
4.15 mg/L (1.22±0.66 mg/L) at the Gbagi upstream, 0.012 to 4.73 (1.35±0.85 mg/L)  
at the Odinjo upstream, 0.01 to 14.14 mg/L (2.23±1.99 mg/L) at the Omi Adio 
upstream and 0.02 to 16.31 mg/L (2.59±1.75 mg/L) at the control site (Awba stream) 
(Figure 4.19a; Appendix 6). It ranged from 0.02 to 9.08 mg/L (1.87±1.10 mg/L) at the 
Irefin downstream, 0.004 to 14.70 mg/L (2.27±2.07 mg/L) at the Gege downstream, 
0.01 to 18.95 mg/L (4.17±2.55 mg/L) at the Gbagi downstream, 0.01 to 0.91 
(0.29±0.16 mg/L) at the Odinjo downstream and 0.01 to 7.11 mg/L (1.88±1.08 mg/L) 
at the Omi Adio downstream (Figure 4.19b; Appendix 6). 
One way analysis of variance showed that the zinc contents of the stream samples 
were not significantly different from one another at P<0.05 (Appendices 6 and 7). 
 
4.4.4.5 Lead   
In March 2008, lead was not detected in all stream water samples except the 
upstreams of Irefin and Gege with values of 0.2625 mg/L and 0.0914 mg/L 
respectively. In May 2008, it was not detected in all stream samples except Gege 
upstream, Gbagi downstream and Odinjo upstream with values of 0.0336 mg/L, 
0.52333 mg/L and 0.0541 mg/L respectively. In July 2008 lead was not detected in all 
stream samples except Gbagi upstream and downstream, and Omi Adio upstream with 
values of 0.2347 mg/L, 0.47628 mg/L and 0.0077 mg/L respectively. In September 
2009, it was not detected at the Gege downstream. In March 2009, lead was not 
detected in all stream samples except its occurrence at the Odinjo downstream with a 
value of 0.499 mg/L. In May 2009, it was not detected in all stream samples. In July  
 
 104 
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25 
20 Upstream Irefin Upstream 
15 Gege Upstream 
Gbagi Upstream 
10 Odinjo Upstream 
Omi Adio Upstream 
5 Awba stream 
0 NL 
-5  
25 Irefin Downstream  
20 Gege Downstream 
Downstream Gbagi Downstream 
15 Odinjo Downstream 
10 Omi Adio Downstream 
Awba stream 
5 
0 NL 
-5 
NL - NESREA LIMIT (0.2 mg/L) 
Sampling Year/Month  
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that zinc was not detected in the samples.  
 
Figure 4.19: Bimonthly variation of zinc values of streams  
                                   (a) Upstream  (b) Downstream 
105 
 
 
Zn (mg/L) Zn (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
2009, it was only observed at the upstream and downstream of Omi Adio with values 
of 0.1410 mg/L and 0.1600 mg/L respectively. In September 2008, it was only 
observed at Omi Adio upstream with a value of 0.0330 mg/L, so also in January 2010 
with a value of 0.0210 mg/L. In November 2009, lead was not detected at the 
upstream of Irefin, Gege and Odinjo, and also at the upstream and downstream of 
Omi Adio (Figure 4.20; Appendices 9 to 19). 
One way analysis of variance showed that the lead contents of the stream samples 
were not significantly different from one another at P<0.05 (Appendix 7). However, 
Duncan’s multiple range tests showed that Gege upstream, Omi Adio upstream and 
the control site (Awba stream) were significantly different from the other sites but 
Gege upstream and Omi Adio upstream were not significantly different from each 
other but each of them was different from the control site (Awba stream) (Appendix 
8). 
 
4.4.4.6 Cadmium    
Cadmium was not detected in March 2008 in all stream samples except at the Odinjo 
downstream with a value of 0.0112 mg/L. In May 2008, cadmium was not detected at 
the downstream of Irefin, Gege, Gbagi and Odinjo. In July 2008, it was not detected 
at the upstream and downstream of Irefin, Gege and Gbagi. In the months of 
September 2008, November 2008 and January 2009, it was not detected in all the 
stream water samples. In March 2009, cadmium was not detected at Gege 
downstream, Omi upstream and downstream, Odinjo upstream and the control site 
(Awba stream). In May 2009, it was not detected in downstream of Irefin and Gege, 
upstream and downstream of Gbagi, Odinjo downstream, and the control site (Awba 
stream). In July 2009, it was not detected in the Gege downstream, Gbagi upstream 
and downstream, and Odinjo upstream. In September 2009, it was not detected at the 
upstream and downstream of Irefin, Omi Adio downstream and the control site (Awba 
stream). In November 2009, it was not detected at the Gege upstream, Gbagi 
upstream, Odinjo upstream, Omi Adio upstream and the control site (Awba stream). 
In January 2010, cadmium was not detected at the Irefin upstream, Gege upstream, 
Gbagi upstream and downstream, Odinjo upstream, Omi Adio upstream and the 
control site (Awba stream) (Figure 4.21; Appendices 9 to 19). 
106 
 
 
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1.2 
Upstream Irefin Upstream 
1 Gege Upstream 
0.8 Gbagi Upstream 
0.6 Odinjo Upstream 
0.4 Omi Adio Upstream 
Awba stream 
0.2 
NL 
0 
-0.2 
1.2 Irefin Downstream  
1 Gege Downstream 
Downstream 
0.8 Gbagi Downstream 
Odinjo Downstream 
0.6 
Omi Adio Downstream 
0.4 Awba stream 
0.2 
NL 
0 
-0.2 
Sampling Year/Month NL - NESREA LIMIT (0.1 mg/L) 
 
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that lead was not detected in the samples.  
 
 
Figure 4.20: Bimonthly variation of lead values of streams 
                                       (a) Upstream  (b) Downstream 
107 
 
 
Pb (mg/L) Pb (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
The bimonthly values of cadmium ranged from 0.02 to 0.08 mg/L (0.04±0.01 mg/L) 
at the Irefin upstream, 0.004 to 0.50 mg/L (0.13±0.09 mg/L) at the Gege upstream, 
0.002 to 0.03 mg/L (0.02±0.01 mg/L) at the Gbagi upstream, 0.01 to 0.08 (0.03±0.02 
mg/L)  at the Odinjo upstream, 0.002 to 0.01 mg/L (0.01±0.001 mg/L) at the Omi 
Adio upstream and 0.002 to 0.07 mg/L (0.04±0.04 mg/L) at the control site (Awba 
stream) (Figure 4.21a; Appendix 6). It ranged from 0.01 to 0.06 mg/L (0.03±0.01 
mg/L) at the Irefin downstream, 0.02 to 0.04 mg/L (0.03±0.01 mg/L) at the Gege 
downstream, 0.01 to 0.02 mg/L (0.01±0.002 mg/L) at the Gbagi downstream, 0.002 to 
0.04 (0.02±0.01 mg/L) at the Odinjo downstream and 0.004 to 0.04 mg/L (0.02±0.01 
mg/L) at the Omi Adio downstream (Figure 4.21b; Appendix 6). 
One way analysis of variance showed that the cadmium contents of the stream 
samples were not significantly different at P<0.05 (Appendices 6 and 7). 
  
4.4.4.7 Nickel   
In March 2008, nickel was not detected in all stream water samples except at the 
Odinjo downstream with a value of 0.1488 mg/L. In May 2008, it was not detected at 
the downstream of Gege and Odinjo. It was not also detected in all samples in July 
2008 except at Omi Adio upstream and the control site (Awba stream) and with 
values of 0.0470 mg/L and 0.2260 mg/L respectively. In September 2008, nickel was 
detected in all stream water samples except Gege downstream, Gbagi upstream and 
Omi Adio downstream. In November 2008, it was not detected at the downstream of 
Irefin and Omi Adio. In January 2009, nickel was not detected at the Gege upstream 
and the upstream and downstream of Gbagi (Figure 4.22; Appendices 9 to 19). 
In the month of March 2009, nickel was not detected in all stream water samples 
except Irefin upstream and Odinjo downstream with values of 0.0090 mg/L and 
0.0540 mg/L respectively. In May 2009, it was only detected at the Gege upstream 
with a value of 0.0400 mg/L. Also in July 2009, it was detected at the Irefin upstream 
and downstream and Omi Adio downstream with the values of 0.0670 mg/L and 
0.0800 mg/L and 0.007 respectively. In September 2009, it was detected at the Irefin 
upstream, Irefin downstream, Gege upstream, Gbagi upstream and Odinjo 
downstream with the values of 0.0060 mg/L, 0.0560 mg/L, 0.0030 mg/L, 0.0030 
mg/L and 0.0610 mg/L respectively. Samples collected in November 2009 from the 
Gege upstream, Gbagi upstream, Odinjo downstream, Omi Adio downstream and the  
 
 108 
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0.5 Irefin Upstream 
Upstream 
Gege Upstream 
0.4 
Gbagi Upstream 
0.3 
Odinjo Upstream 
0.2 Omi Adio Upstream 
0.1 Awba stream 
0 NL 
-0.1 
-0.2 
0.5 Irefin Downstream  
0.4 Downstream Gege Downstream 
Gbagi Downstream 
0.3 Odinjo Downstream 
0.2 Omi Adio Downstream 
Awba stream 
0.1 
0   NL 
-0.1 
NL - NESREA LIMIT (0.01 mg/L) 
Sampling Year/Month  
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that cadmium was not detected in the samples.  
 
Figure 4.21: Bimonthly variation of cadmium values of streams  
                                      (a) Upstream  (b) Downstream
109 
 
 
Cd (mg/L) 
U Cd (mg/L) NIVERSITY OF IBADAN LIBRARY
 
control site (Awba stream) had no nickel content. Nickel was not detected in January 
2010 in all stream water samples except the samples from Irefin upstream, Irefin 
downstream and Odinjo downstream with the values of 0.0890 mg/L, 0.0980 mg/L 
and 0.0050 mg/L respectively (Figure 4.22; Appendices 9 to 19). 
One way analysis of variance showed that the nickel contents of the stream water 
samples were not significantly different from one another at P<0.05 (Appendix 7). 
However, Duncan’s multiple range tests revealed that Gbagi upstream and the control 
site (Awba stream) were significantly different from the other stream samples and 
they were also significantly different from each other at P<0.05 (Appendix 8). 
 
4.4.4.8 Chromium 
Chromium was not analysed in March and May 2009. It was not detected in all stream 
samples in the months of November 2008, May 2009, September 2009 and January 
2010. In July 2008, it was not detected in Gege downstream, Irefin upstream and 
downstream, and Gbagi upstream and downstream. In September 2008, it was only 
detected at the Irefin upstream and downstream, and Gege upstream with the values of 
0.1180 mg/L, 0.1804 mg/L, and 0.1097 mg/L respectively. In January 2009, it was 
only detected at the Gbagi upstream with a value of 0.0255 mg/L. In March 2009, it 
was detected at the downstream of Gbagi and Odinjo with the values of 0.0910 mg/L 
and 0.0340 mg/L respectively. In July 2009, it was only detected at the Omi Adio 
downstream with a value of 0.0190 mg/L. In November 2009, it was only detected at 
the Gege downstream with a value of 0.0660 mg/L (Figure 4.23 to 20; Appendices 9 
to 19).   
One way analysis of variance showed that the chromium contents of the stream 
samples were not significantly different from one another at P<0.05 (Appendix 7). 
 
4.5 Result of analysis of soil samples from the banks of the streams 
4.5.1 Bimonthly variation of physico-chemical characteristics of soil samples 
from the banks of the streams 
The bimonthly range and mean values of the physico-chemical characteristics of soil 
samples from the streams are shown in Appendix 20. Details are shown in 
Appendices 26 to 31.  
110 
 
 
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0.3 Irefin Upstream 
Gege Upstream 
0.25 
Upstream Gbagi Upstream 
0.2 Odinjo Upstream 
Omi Adio Upstream 
0.15 Awba stream 
0.1 NL 
0.05 
0 
-0.05 
0.3 Irefin Downstream  
Gege Downstream 
0.25 
Gbagi Downstream 
0.2 Downstream Odinjo Downstream 
Omi Adio Downstream 
0.15 
Awba stream 
0.1 NL 
0.05 
0 
-0.05 
NL - NESREA LIMIT (0.1 mg/L) 
Sampling Year/Month  
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that nickel was not detected in the samples.  
 
Figure 4.22: Bimonthly variation of nickel values of streams  
                                     (a) Upstream  (b) Downstream
111 
 
 
Ni (mg/L) Ni (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
0.6 
Upstream 
0.5 NL 
Irefin Upstream 
0.4 Gege Upstream 
0.3 Gbagi Upstream 
0.2 Odinjo Upstream 
Omi Adio Upstream 
0.1 
Awba stream 
0 
-0.1 
0.6 Downstream 
0.5 NL 
0.4 Irefin Downstream  
0.3 Gege Downstream 
0.2 Gbagi Downstream 
Odinjo Downstream 
0.1 
Omi Adio Downstream 
0 
Awba stream 
-0.1 
NL - NESREA LIMIT (0.5 mg/L) 
Sampling Year/Month  
NOTE: Blank spaces indicated that the control site (Awba stream) was not sampled in the months of March and May, 2008. 
Other blank spaces indicated that chromium was not detected in the samples.  
 
Figure 4.23: Bimonthly variation of chromium values of streams  
                                     (a) Upstream  (b) Downstream 
112 
 
 
Cr (mg/L) Cr (mg/L) 
UNIVERSITY OF IBADAN LIBRARY
 
4.5.1.1 Soil particle size distribution 
The percentage sand contents of the soil samples from the stream banks ranged from 
90 to 100 % (94.75±0.87 %) at the Irefin stream, 94 to 97 % (95.83±0.34 %) at the 
Gege stream, 83 to 97 % (87.91±1.27 %) at the Gbagi stream, 80 to 97 % (91.83±1.56 
%) at the Odinjo stream, 68 to 94 % (82.50±2.58 %) at the Omi Adio stream and 90 to 
99 % (92.90±0.95 %) at the control site (Awba stream) (Figure 4.24a; Appendix 20). 
The percentage silt content of the soil samples ranged from 0 to 5 % (2.25±0.46 %) at 
the Irefin stream, 1 to 4 % (2.17±0.30 %) at the Gege stream, 1 to 5 % (2.75±0.39 %) 
at the Gbagi stream, 0 to 5 % (2.00±0.43 %) at the Odinjo stream, 1 to 16 % 
(5.25±1.27 %) at the Omi Adio stream and 0 to 4 % (2.11±0.35 %) at the control site 
(Awba stream) (Figure 4.24b; Appendix 20). 
The percentage clay content of the soil samples ranged from 1 to 6 % (3.17±0.60 %) 
at the Irefin stream, 1 to 5 % (1.83±0.44 %) at the Gege stream, 2 to 15 % (9.33±1.33 
%) at the Gbagi stream, 1 to 18 % (6.17±1.59 %) at the Odinjo stream, 4 to 16 % 
(10.83±1.19 %) at the Omi Adio stream and 1 to 8 % (5.20±0.81 %) at the control site 
(Awba stream) (Figure 4.24c; Appendix 20). 
Using their mean values for textural classification, the soil samples of the Irefin 
stream, Gege stream and control site (Awba stream) were sandy while those from 
Gbagi stream, Odinjo stream and Omi Adio stream were loamy sand (Appendix 21). 
 
4.5.1.2 Hydrogen ion concentration (pH) 
The range of pH values of the soil samples were 6.40 to 8.30 (7.27±0.15) at the Irefin 
stream, 6.40 to 8.40 (7.32±0.16) at the Gege stream, 6.70 to 8.90 (7.49±0.21) at the 
Gbagi stream, 6.40 to 9.20 (7.61±0.20) at the Odinjo stream, 6.60 to 8.10 (7.34±0.11) 
at the Omi Adio stream and 6.00 to 7.50 (6.90±0.15) at the control site (Awba 
stream), (Figure 4.25a; Appendix 20). 
One way analysis of variance showed that the pH of the soil samples were not 
significantly different at P<0.05 (Appendix 24). However, Duncan’s multiple range 
tests showed some significant differences of some of the samples at P<0.05. It showed 
that the pH of the soil from the control site was significantly different from those of 
the soil from Gbagi and Odinjo streams (Appendix 25).   
 
113 
 
UNIVERSITY OF IBADAN LIBRARY
 
  
120 
100 
80 
60 
40 
20 
0 
25 
20 
15 
10 
5 
0 
-5 
25 
20 
15 
10 
5 
0 
-5 
Sampling Year/Month 
Irefin Gege Gbagi Odinjo Omi Adio Awba Stream 
 
 
Figure 4.24: Bimonthly variation of particle size distribution values of soil from 
streams’ banks   (a) Sand        (b)  Silt       (c) Clay  
 
114 
 
UN % Silt % Sand % Clay IVERSITY OF IBADAN LIBRARY
 
4.5.1.3 Electrical conductivity 
The range of the electrical conductivity values of the soil samples were 455.00 to 
1465.00 µS/cm (770.58±82.81 µS/cm) at the Irefin stream, 889.00 to 1809.00 µS/cm 
(1346.92±99.48 µS/cm) at the Gege stream, 226.00 to 11570.00 µS/cm 
(2723.42±933.87 µS/cm) at the Gbagi stream, 352.00 to 1285.00 µS/cm 
(617.92±80.08 µS/cm) at the Odinjo stream, 128.70 to 1386.00 µS/cm 
(610.38±103.37 µS/cm) at the Omi Adio stream, 46.60 to 498.00 µS/cm 
(199.25±55.29 µS/cm) at the control site (Awba stream) (Figure 4.25b; Appendix 21). 
One way analysis of variance showed that the electrical conductivity values of the soil 
samples were significantly different at P<0.05 (Appendix 24). Duncan’s multiple 
range tests also showed that the electrical conductivity value of the soil from Gbagi 
stream was significantly different from all soil samples (Appendix 25).  
 
4.5.1.4 Total organic carbon 
The bimonthly total organic carbon observed in the soil samples from the Irefin, 
Gege, Gbagi, Odinjo, Omi Adio streams and control site (Awba stream) were 0.17 to 
1.89 % (0.83±0.16), 0.08 to 1.24 % (0.60±0.13 %), 0.37 to 6.2 % (2.42±0.59 %), 0.78 
to 2.10 % (1.47±0.22 %), 0.75 to 5.29 % (2.03±0.40) and 0.08 to 1.53 % (0.72±0.19 
%) respectively (Figure 4.25c; Appendix 20).  
The soil sample from Odinjo stream had no total organic carbon in September 2008 
and throughout the sampling months of 2009. In September 2008, Gbagi soil had no 
total organic carbon. So also the soil sample from Gege stream had no total organic 
carbon in September 2009. In the month of November 2009, the soil samples from the 
Omi Adio stream and the control site (Awba stream) had no total organic carbon 
(Figure 4.25c).  
One way analysis of variance showed that the total organic carbon contents of the soil 
samples were significantly different at P<0.05 (Appendix 24). Duncan’s multiple 
range tests also showed that the total organic carbon contents of the soil from Gbagi 
and Omi Adio streams were significantly different from all soil samples except that of 
Odinjo stream (Appendix 25).  
 
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4.5.1.5 Total organic matter 
The bimonthly total organic matter observed ranged from 0.30 to 3.27 % (1.44±0.27 
%), 0.14 to 2.14 % (1.03±0.22 %), 0.63 to 10.72 % (4.18±1.02 %), 1.35 to 3.63 % 
(2.54±0.38 %), 1.30 to 9.15 % (3.51±0.68 %) and 0.14 to 2.65 % (1.25±0.32 %) in the 
soil samples from the Irefin, Gege, Gbagi, Odinjo, Omi Adio streams and control site 
(Awba stream) respectively. The same trend of none detection of total organic carbon 
was also seen in total organic matter of the samples (Figure 4.25d). 
One way analysis of variance showed that the total organic matter contents of the soil 
samples were significantly different at P<0.05 (Appendix 24). Duncan’s multiple 
range tests also showed the trend seen in the total organic carbon (Appendix 25). 
 
4.5.2 Bimonthly variation of anions of soil samples from the banks of streams 
The range and mean values of the anions of soil samples from the streams are shown 
in Appendix 22. Details are shown in Appendices 26 to 31. 
 
4.5.2.1 Nitrate – nitrogen 
Nitrate – nitrogen was not detected in the soil samples from the bank of Irefin stream 
in July 2008, January 2009, May – September 2009, and January 2010. In the months 
of March 2008, November 2008 and 2009, September 2009, and January 2010, it was 
not detected in the soil samples from the bank of Gege stream. It was not detected in 
the soil samples from the banks of Gbagi stream in the months of May to September 
2008, January 2009, May, July, November 2009, and January 2010. Nitrate – nitrogen 
was not detected in the soil samples from the banks of Odinjo stream in the months of 
May and September 2008, throughout the sampling months of 2009 and also in 
January 2010. In May 2008, November 2008, May 2009, September and November 
2009, and also January 2010, nitrate – nitrogen was not detected in the soil samples 
from the bank of Omi Adio streams. Throughout the sampling period, nitrate – 
nitrogen was not detected in the soil samples from the banks of the control site (Awba 
stream) (Figure 4.26a; Appendices 26 to 31). 
The bimonthly variation of nitrate – nitrogen from the banks of the streams ranged 
from 255.20 to 1132.78 mg/kg (658.71±143.79 mg/kg) at the Irefin stream, 21.12 to 
840.18 mg/kg (507.86±143.79 mg/kg) at the Gege stream, 196.68 to 1425.38 mg/kg  
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Irefin Gege Gbagi Odinjo Omi Adio Awba Stream 
 
 
Figure 4.25: Bimonthly variation of physico-chemical values of soil from 
streams’ banks   (a) pH        (b)  EC       (c) TOC     (d) TOM  
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(635.47±277.02 mg/kg) at the Gbagi stream, 196.68 to 1249.82 mg/kg 
(606.17±325.78 mg/kg) at the Odinjo stream and 21.12 to 840.18 mg/kg 
(333.30±137.25 mg/kg) at the Omi Adio stream (Figure 4.26a; Appendix 22). 
One way analysis of variance showed that the nitrate - nitrogen contents of the soil 
samples were not significantly different at P<0.05 (Appendix 24).  
 
4.5.2.2 Sulphate - sulphur 
In the months of March 2008 and September 2008, sulphate – sulphur was not 
detected in all soil samples except in the soil from the bank of Gege stream with 
values of 39.63 mg/kg and 17.88 mg/kg respectively. In May 2008, it was detected 
only in the soil from the Irefin stream with a value of 9.75 mg/kg. In July 2008, it was 
only detected in the soil samples from the banks of Odinjo stream and control site 
(Awba stream) with values of 9.75 mg/kg and 34.25 mg/kg respectively. In 
September 2008, it was only detected in the soil sample from Gege stream with a 
value of 17.88 mg/kg. In November 2008, it was not detected in the soil from the 
control site (Awba stream). In January 2009, it was not detected in the soil sample 
from the bank of Irefin stream. In the month of March 2009, it was not detected in the 
soil samples from Gege and Omi Adio streams. In July 2009, it was detected in the 
soil samples from Odinjo and Omi Adio soils with values of 1.63 mg/kg and 23.38 
mg/kg respectively. In September 2009, sulphate – sulphur was detected only at the 
control site (Awba stream) with a value of 1.63 mg/kg. In November 2009, it was not 
detected in the soil samples from the banks of Irefin stream, Omi Adio stream and 
control site (Awba stream). In January 2010, it was not detected in the soil samples 
from the banks of Odinjo and Omi Adio streams (Figure 4.26b). 
One way analysis of variance showed that the sulphate – sulphur contents of the soil 
samples were not significantly different at P<0.05 (Appendix 24). 
 
4.5.3 Bimonthly variation of cations of soil samples from the banks of streams 
The range and mean values of the cations of soil samples from the banks of the 
streams are shown in Appendix 22. Details are shown in Appendices 26 to 31. 
 
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4.5.3.1 Phosphorus 
The bimonthly range of 61.04 to 150.08 mg/kg (110.72±8.47 mg/kg) of phosphorus 
was observed in the soil sample from the bank of Irefin stream, Gege soil had a range 
of 2.93 to 108.08 mg/kg (79.59±9.18 mg/kg), Gbagi soil had a range of 58.24 to 
123.76 mg/kg (85.94±6.29 mg/kg), Odinjo soil had a range of 45.36 to 115.92 
(73.59±7.14 mg/kg) mg/kg, Omi Adio soil  had a range of 19.04 to 115.92 mg/kg 
(74.30±8.06 mg/kg) while the control site (Awba stream) had a range of 11.20 to 
58.24 mg/kg (36.65±4.69 mg/kg) (Figure 4.26c; Appendix 22). 
One way analysis of variance showed that the phosphorus contents of the soil samples 
were significantly different at P<0.05 (Appendix 24). Duncan’s multiple range tests 
also showed that the phosphorus content of the soil from the banks of Irefin stream 
and control site (Awba stream) were significantly different from phosphorus contents 
of all the other soil samples and also different from each other (Appendix 25).  
 
4.5.3.2 Calcium  
Calcium was not detected in the soil samples from the banks of the Omi Adio 
dumpsite and control site (Awba stream) in the months of September and May 2009 
respectively (Appendices 26 – 31). 
The bimonthly calcium content of soil samples observed at the banks of Irefin, Gege, 
Gbagi, Odinjo, Omi Adio streams and control site (Awba stream) ranged from 
5064.80 to 28486.70 mg/kg, 7004.00 to 30466.30 mg/kg, 13286.20 to 58110.00 
mg/kg, 261.70 to 23406.40 mg/kg, 762.20 to 37041.40 mg/kg and 14447.70 to 
46010.20 mg/kg respectively (Figure 4.26d).  
The mean values observed in the soil samples from the banks of Irefin, Gege, Gbagi, 
Odinjo, Omi Adio streams and control site (Awba stream) were (20644.70±2294.42 
mg/kg), (18978.10±3040.18 mg/kg), (27404.10±4148.02 mg/kg), (16181.00±2652.98 
mg/kg), (15963.00±4143.68 mg/kg) and (23229±343.81 mg/kg) respectively 
(Appendix 22). 
One way analysis of variance showed that the calcium contents of the soil samples 
were not significantly different at P<0.05 (Appendix 24). However, Duncan’s 
multiple range tests showed some significant differences of some of the samples at 
P<0.05. It showed that the calcium content of the soil from Gbagi stream was 
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significantly different from the calcium contents of Odinjo and Omi Adio streams but 
not different from calcium contents of Irefin, Gege and the control site (Awba stream) 
(Appendix 25). 
 
4.5.3.3 Magnesium 
The bimonthly values of magnesium content of soil samples from the steams’ banks 
ranged from 668.70 to 2175.64 mg/kg (1067.88±144.13 mg/kg) at the Irefin stream, 
746.40 to 1676.54 mg/kg (1181.59±101.17 mg/kg) at the Gege stream, 733.80 to 
5928.90 mg/kg (1682.56±451.75 mg/kg) at the Gbagi stream, 162.60 to 2073.08 
mg/kg (1082.18±180.56 mg/kg) at the Odinjo stream, 229.80 to 1898.72 mg/kg 
(851.95±175.35 mg/kg) at the Omi Adio stream and 206.70 to 1145.40 mg/kg 
(693.69±91.67 mg/kg) at the control site (Awba stream) (Figure 4.27a; Appendix 22).   
One way analysis of variance showed that the magnesium contents of the soil samples 
were not significantly different at P<0.05 (Appendix 24). However, Duncan’s 
multiple range tests showed some significant differences of some of the samples at 
P<0.05. It showed that the magnesium content of the soil from Gbagi stream was 
significantly different from the magnesium content of the Omi stream and control site 
(Awba stream) but it was not different from the other soil samples (Appendix 25). 
 
4.5.3.4 Sodium 
In September 2008 and May 2009, sodium was not detected in the soil samples from 
the Odinjo stream and the control site (Awba stream) respectively (Figure 2.27b). 
The bimonthly sodium values observed ranged from 100 to 900 mg/kg (550.45±67.37 
mg/kg) in the soil sample from the Irefin stream, 100 to 900 mg/kg (570.09±77.85 
mg/kg) in the sample from Gege stream), 400 to 3700 mg/kg (1138.73±337.08 
mg/kg) in the sample from Gbagi stream, 200 to 1500 mg/kg (680.55±104.04 mg/kg) 
in the sample from Odinjo stream, 100 to 900 mg/kg (464.00±67.50 mg/kg) in the 
sample from Omi Adio stream and 200 to 1200 mg/kg (600±104.08 mg/kg) in the soil 
sample from the control site (Awba stream) (Figure 4.27b; Appendix 22). 
One way analysis of variance showed that the sodium contents of the soil samples 
were not significantly different at P<0.05 (Appendix 24). However, Duncan’s 
multiple range tests showed that the sodium content of the soil from the bank of 
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Irefin Gege Gbagi Odinjo Omi Adio Awba Stream 
 
NOTE: Blank spaces indicated that the control site (Awba stream) was not 
sampled in the months of March and May, 2008. Other blank spaces indicated 
2-
that NO3 – N,  SO4 - S and Ca were not detected in the samples. 
 
Figure 4.26: Bimonthly variation of some anions and some cations values of soil 
2-
from stream banks     (a) NO3 - N        (b)  SO4 - S       (c) P (d) Ca  
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IVERSITY OF IBADAN LIBRARY
 
Gbagi stream was significantly different from sodium contents of all the other soil 
samples except those from Odinjo stream’s bank (Appendix 25). 
 
4.5.3.5 Potassium 
The bimonthly values of potassium observed in the soil samples ranged from 630 to 
1230 mg/kg (905.27±61.47 mg/kg), 648 to 1630 mg/kg (973.45±88.72 mg/kg), 530 to 
19330 mg/kg (2665.00±1672.21 mg/kg), 330 to 2230 mg/kg (944.00±190.51 mg/kg), 
130 to 1030 mg/kg (596.91±87.52 mg/kg) and 130 to 3230 mg/kg (596.91±87.52 
mg/kg) in the soil samples from the banks of Irefin, Gege, Gbagi, Odinjo, Omi Adio 
streams and control site (Awba stream),respectively (Figure 4.27c; Appendix 22). 
One way analysis of variance showed that the potassium contents of the soil samples 
were not significantly different at P<0.05 (Appendix 24).  
 
4.5.3.6 Cation exchange capacity (CEC) 
The bimonthly range of cation exchange capacity observed at the soil from the banks 
of Irefin, Gege, Gbagi, Odinjo, Omi Adio streams and control site (Awba stream) 
were 34.91 to 152.65 Cmol/kg, 44.27 to 165.88 Cmol/kg, 97.13 to 401.23 Cmol/kg, 
7.40 to 143.38 Cmol/kg, 7.62 to 200.00 Cmol/kg and 2.03 to 235.00 Cmol/kg 
respectively (Figure 4.27d; Appendix 22). 
The mean values observed at the control site (Awba stream), Irefin stream, Gege 
stream, Gbagi stream, Odinjo stream and Omi Adio stream were (112.83±14.85 
Cmol/kg), (115.92±16.17 Cmol/kg), (167.41±34.21 Cmol/kg), (101.58±12.94 
Cmol/kg) and (79.61±21.35 Cmol/kg),  (114.30±19.58 Cmol/kg) respectively 
(Appendix 22). 
One way analysis of variance indicated that the cation exchange capacities of the soil 
samples from all the streams’ banks were not significantly different from one another 
at P<0.05 (Appendix 24). However, the cation exchange capacities of the soil samples 
from the banks of Gbagi and Omi Adio streams were significantly different from each 
other at P<0.05 (Appendix 25).  
 
 
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Sampling Year/Month 
Irefin Gege Gbagi Odinjo Omi Adio Awba Stream 
 
NOTE: Blank spaces indicated that the control site (Awba stream) was not 
sampled in the months of March and May, 2008. Other blank spaces indicated 
that Mg, Na, K and CEC were not detected in the samples. 
 
Figure 4.27: Bimonthly variation of some cations values and cation exchange 
capacities of soil from streams’ banks (a) Mg     (b) Na (c) K     (d) CEC  
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4.5.4 Bimonthly variation of trace and heavy metals of soil samples from the 
banks of streams 
The range and mean values of the trace and heavy metals of soil samples from the 
banks of the streams are shown in Appendix 23. Details are shown in Appendices 26 
to 31. 
 
4.5.4.1 Iron 
The bimonthly iron content of soil samples from the banks of Irefin, Gege, Gbagi, 
Odinjo, Omi Adio streams and the control site (Awba stream) were 21374.80 to 
47141.30 mg/kg, 24623.80 to 37684.90 mg/kg, 25462.90 to 58402.80 mg/kg, 
15693.70 to 81733.80 mg/kg, 20268.40 to 38424.40 mg/kg and 6852.40 to 19590.10 
mg/kg respectively (Figure 4.28a; Appendix 23). 
The mean values observed at the Irefin, Gege, Gbagi, Odinjo, Omi Adio streams and 
control site (Awba stream)  were (31605.76±2606.91 mg/kg), (28676.30±1402.12 
mg/kg), (33428.22±33193.60 mg/kg), (31322.16±5861.84 mg/kg), (2903.43±1944.15 
mg/kg) and (13146.50±1428.28 mg/kg) respectively (Appendix 23). 
One way analysis of variance showed that the iron contents of the soil samples were 
significantly different at P<0.05 (Appendix 24). Duncan’s multiple range tests also 
showed that the iron content of the soil from the bank of the control site (Awba 
stream) was significantly different from iron contents of all other soil samples 
(Appendix 25).  
 
4.5.4.2 Manganese 
The bimonthly values of manganese content of soil samples from the banks of streams 
ranged from 13.47 to 1692.90 mg/kg at the Irefin stream, 12.60 to 505.90 mg/kg at the 
Gege stream, 42.78 to 642.90 mg/kg at the Gbagi stream, 40.98 to 559.40 mg/kg at 
the Odinjo stream, 35.60 to 506.00 mg/kg at the Omi Adio stream and 128.80 to 
506.00 mg/kg at the control site (Awba stream) (Figure 4.28b; Appendix 23).  
The mean values observed were (465.73±165.80 mg/kg), (385.79.72±48.82 mg/kg), 
(420.49±65.99 mg/kg), (317.69±44.23 mg/kg), (320.98±58.16 mg/kg) and 
(255.15±36.89 mg/kg), at the control site (Awba stream), Irefin, Gege, Gbagi, Odinjo 
and Omi Adio streams respectively (Appendix 23). 
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115 
 
One way analysis of variance showed that the manganese contents of the soil samples 
were not significantly different at P<0.05 (Appendix 24). However, Duncan’s 
multiple range tests showed that manganese contents of soil samples from the banks 
of Irefin stream was significantly different from that of control (Awba stream) 
(Appendix 25). 
 
4.5.4.3 Copper 
Copper was not detected in the soil samples from the Irefin stream and the control site 
(Awba stream) in the months of May 2008 and May 2009 respectively (Figure 4.28c). 
The bimonthly values of copper content of soil samples from streams’ banks ranged 
from 56.60 to 590.10 mg/kg at the Irefin stream, 33.90 to 594.30 mg/kg at the Gege 
stream, 17.40 to 210.00 mg/kg at the Gbagi stream, 11.90 to 130.00 mg/kg at the 
Odinjo stream, 15.90 to 70.40 mg/kg at the Omi Adio stream and 2.50 to 37.00 mg/kg 
at the control site (Awba stream) (Figure 4.28c; Appendix 23).   
The mean values observed at the banks of Irefin stream, Gege stream, Gbagi stream, 
Odinjo stream, Omi Adio stream and the control site (Awba stream) were  
(154.86±63.27 mg/kg), (118.04±60.06 mg/kg), (86.63±21.99 mg/kg), (39.34±9.62 
mg/kg), (40.51±5.27 mg/kg) and (15.42±3.38 mg/kg) respectively (Appendix 23). 
One way analysis of variance showed that the copper contents of the soil samples 
from the streams’ banks were significantly different at P<0.05 (Appendix 24). 
Duncan’s multiple range tests also showed some significant differences at P<0.05. It 
showed that the copper content of the soil from bank of Irefin stream was significantly 
different from the copper content of all the soil from other streams’ banks except 
those of the Gege and Gbagi streams (Appendix 25). 
 
4.5.4.4 Zinc 
Zinc was not detected in the soil from the bank of Odinjo stream in March 2009. In 
May and July 2009, it was also not detected at the control site (Awba stream) (Figure 
4.28d; Appendices 26 to 31). 
The bimonthly values of zinc observed in the soil samples ranged from 207.70 to 
760.40 mg/kg (484.77±68.16 mg/kg), 342.10 to 684.40 mg/kg (514.05±45.64 mg/kg), 
88.30 to 961.60 mg/kg (321.68±112.29 mg/kg), 2.26 to 669.10 mg/kg (261.07±65.90 
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mg/kg), 2.65 to 369.40 mg/kg (188.38±38.23 mg/kg) and 11.80 to 67.80 mg/kg 
(45.34±7.13 mg/kg) in the soil samples from the banks of Irefin, Gege, Gbagi, Odinjo, 
Omi Adio streams and control site (Awba stream) respectively (Figure 4.28d; 
Appendix 23). 
One way analysis of variance showed that the zinc contents of the soil samples were 
significantly different at P<0.05 (Appendix 24). Duncan’s multiple range tests also 
showed that the zinc content of the soil from Gege stream was significantly different 
from zinc content of the control site (Awba stream) (Appendix 25).  
 
4.5.4.5 Lead 
Lead was detected in all soil samples in May 2008 except in the soil sample from Omi 
Adio stream. It was not detected in the soil sample from the control site (Awba 
stream) in September 2008 and May 2009 (Figure 4.29a). 
The bimonthly values of lead observed in the soil samples ranged from 0.77 to 787.70 
mg/kg (293.18±80.04 mg/kg), 64.00 to 178.70 mg/kg (102.19±12.41 mg/kg), 76.60 to 
394.70 mg/kg (161.73±34.83 mg/kg), 27.00 to 1213.00 mg/kg (227.27±100.59 
mg/kg), 44.10 to 458.20 mg/kg (177.21±42.00 mg/kg) and 11.70 to 87.70 mg/kg 
(51.61±9.79 mg/kg) in the soil samples from the banks of Irefin, Gege, Gbagi, Odinjo, 
Omi Adio streams and control site (Awba stream),respectively (Figure 4.29a; 
Appendix 23). 
One way analysis of variance showed that the lead contents of the soil samples from 
the streams’ banks were significantly different at P<0.05 (Appendix 24). Duncan’s 
multiple range tests also showed that the lead content of the soil from the bank of 
Irefin stream was significantly different from those of other soil samples except that 
of the Odinjo stream (Appendix 25). 
 
4.5.4.6 Cadmium 
The bimonthly cadmium values observed ranged from 1.3000 to 3.0000 mg/kg 
(1.96±0.22 mg/kg), 1.0000 to 3.30000 mg/kg (1.71±0.30 mg/kg), 0.7000 to 2.7000 
mg/kg (1.80±0.20 mg/kg), 1.3000 to 2.6000 mg/kg (1.85±0.14 mg/kg), 0.5000 to  
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Irefin Gege Gbagi Odinjo Omi Adio Awba Stream 
 NOTE: Blank spaces indicated that the control site (Awba stream) was not 
sampled in the months of March and May, 2008. Other blank spaces indicated 
that Fe, Mn, Cu and Zn were not detected in the samples. 
 
Figure 4.28: Bimonthly variation of trace and heavy metal values of soil from 
streams’ banks    (a) Fe        (b) Mn       (c) Cu  (d) Zn  
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2.1000 mg/kg (1.20±0.17 mg/kg) and 0.4000 to 1.6000 mg/kg (0.99±0.13 mg/kg) at 
the banks of Irefin, Gege, Gbagi, Odinjo, Omi Adio streams and control site (Awba 
stream) respectively (Figure 4.29b; Appendix 23). 
One way analysis of variance showed that the cadmium contents of the soil samples 
from the streams’ banks were significantly different at P<0.05 (Appendix 24). 
Duncan’s multiple range tests also showed that the cadmium content of the soil from 
the banks of Omi Adio stream and control stream (Awba) were significantly different 
from those of other soil samples but not different from each other (Appendix 25). 
 
4.5.4.7 Nickel 
The bimonthly values of nickel content of soil samples ranged from 11.20 to 19.20 
mg/kg (16.04±1.07 mg/kg) at the Irefin stream, 12.10 to 28.80 mg/kg (17.65±1.84 
mg/kg) at the Gege stream, 14.80 to 23.60 mg/kg (19.29±1.02 mg/kg) at the Gbagi 
stream, 2.20 to 40.20 mg/kg (14.69±3.56 mg/kg) at the Odinjo stream, 2.65 to 24.9 
mg/kg (14.71±2.1 mg/kg) at the Omi Adio stream and 1.10 to 17.60 mg/kg 
(8.47±1.55 mg/kg) at the control site (Awba stream)  (Figure 4.29c; Appendix 23). 
One way analysis of variance showed that the nickel contents of the soil samples were 
not significantly different at P<0.05 (Appendix 24). However, Duncan’s multiple 
range tests showed some significant differences of some of the samples at P<0.05. It 
showed that the nickel content of the soil from the bank of control site was 
significantly different from the nickel content of the soil from the other soil samples 
(Appendix 25). 
 
4.5.4.8 Chromium  
Chromium was not detected in all soil samples in March 2008 except the soil sample 
from the bank of Gbagi stream with a value of 38.61 mg/kg. In all soil samples 
analysed in the month of May 2008, chromium was not detected except in the sample 
from the bank of Omi Adio stream with a value of 3.81 mg/kg (Figure 4.28d). 
The bimonthly values of chromium content of soil samples ranged from 5.10 to 32.90 
mg/kg (19.59±3.57 mg/kg) at the Irefin stream, 15.60 to 37.50 mg/kg (24.48±2.35 
mg/kg) at the Gege stream, 23.20 to 56.80 mg/kg (42.99±3.77 mg/kg) at the Gbagi 
stream, 5.90 to 42.70 mg/kg (21.01±3.14 mg/kg) at the Odinjo stream, 3.81 to 37.90 
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mg/kg (24.62±3.44 mg/kg) at the Omi Adio stream and 4.20 to 27.70 mg/kg 
(14.51±2.50 mg/kg) at the control site (Awba stream)  (Figure 4.29d; Appendix 23). 
One way analysis of variance showed that the chromium contents of the soil samples 
from the banks of the streams were significantly different at P<0.05 (Appendix 24). 
Duncan’s multiple range tests showed that the chromium content of the soil from 
Gbagi stream was significantly different from the chromium contents of all other soil 
samples at P<0.05 (Appendix 25).  
 
4.6 Result of analysis of soil samples from the dumpsites 
4.6.1 Bimonthly variation of physico-chemical characteristics of soil samples 
from the dumpsites 
The range and mean values of the physico-chemical characteristics of soil samples 
from the dumpsites are shown in Appendix 32. Details are shown in Appendices 37 to 
42. 
 
4.6.1.1 Soil particle size distribution 
The percentage sand contents of the soil samples ranged from 68 to 92% (84.00±1.93 
%) at the Ojokondo dumpsite, 70 to 85 % (78.03±1.66 %) at the Olodo dumpsite, 79 
to 87 % (83.75±0.79 %) at the Moniya dumpsite, 74 to 94 % (86.75±1.64 %) at the Idi 
Ope dumpsite, 6 to 83 % (69.08±2.82 %) at the Oremeji dumpsite and 84 to 92 % 
(87.30±0.82 %) at the control site (Balewa) (Figure 4.30a; Appendix 32). 
The percentage silt content of the soil samples ranged from  1 to 30 % (5.00±2.33 %) 
at the Ojokondo dumpsite, 2 to 7 % (4.50±0.54 %) at the Olodo dumpsite, 1 to 8 % 
(3.33±0.48 %) at the Moniya dumpsite, 1 to 11 % (2.83±0.80 %) at the Idi Ope 
dumpsite, 2 to 12 % (7.42±1.02 %) at the Oremeji dumpsite and 2 to 5 % (3.20±0.39 
%) at the control site (Balewa) (Figure 4.30b; Appendix 32). 
The percentage clay content of the soil samples ranged from 2 to 19 % (10.83±1.43 
%) at the Ojokondo dumpsite, 10 to 23 % (16.42±1.12 %) at the Olodo dumpsite, 10 
to 18 % (12.92±0.68 %) at the Moniya dumpsite, 4 to 15 % (10.25±1.07 %) at the Idi 
Ope dumpsite, 13 to 36 % (23.50±2.17 %) at the Oremeji dumpsite and 6 to 12 % 
(9.75±0.77 %) at the control site (Balewa) (Figure 4.30c; Appendix 32). 
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that Pb, Cd, Ni and Cr were not detected in the samples. 
 
Figure 4.29: Bimonthly variation of trace and heavy metals values of soil from 
streams’ banks   (a) Pb   (b) Cd       (c) Ni  (d) Cr  
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Using their mean values for textural classification, the soil from the control site 
(Balewa), Ojokondo, Olodo, Moniya and Idi Ope dumpsites were all loamy sand 
while the soil from Oremeji dumpsite were sandy clay loam (Appendix 21). 
 
4.6.1.2 Hydrogen ion concentration (pH) 
The bimonthly values of the pH of soil samples ranged from 6.30 to 8.40 (7.48±0.15) 
at the Ojokondo dumpsite, 6.60 to 9.00 (7.65±0.16) at the Olodo dumpsite, 6.20 to 
8.00 (7.33±0.14) at the Moniya dumpsite, 6.80 to 8.10 (7.57±0.12) at the Idi Ope 
dumpsite, 7.20 to 8.00 (7.62±0.07) at the Oremeji dumpsite and 6.60 to 8.30 
(7.23±0.20) at the control site (Balewa) (Figure 4.31a; Appendix 32).   
One way analysis of variance showed that the pH values in the soil samples were not 
significantly different at P<0.05 (Appendix 35). 
 
4.6.1.3 Electrical conductivity 
The bimonthly electrical conductivity values of the soil samples ranged from 662.00 
to 3960.00 µS/cm (1978.50±291.17 µS/cm) at the Ojokondo dumpsite, 119.70 to 
11780.00 µS/cm (3444.08±1205.16 µS/cm) at the Olodo dumpsite, 274.00 to 6390.00 
µS/cm (1628.25±467.00µS/cm) at the Moniya dumpsite, 164.50 to 3790.00 µS/cm  
(1073.38±325.05 µS/cm) at the Idi Ope dumpsite, 293.00 to 1360.00 µS/cm 
(802.00±105.35 µS/cm) at the Oremeji dumpsite and 126.40 to 343.00 µS/cm 
(212.15±19.72 µS/cm) at the control site (Balewa) (Figure 4.31b; Appendix 32).   
One way analysis of variance showed that the electrical conductivity values in the soil 
samples were significantly different at P<0.05 (Appendix 35). Duncan’s multiple 
range tests also showed that the electrical conductivity of the soil from the Olodo 
dumpsite was significantly different from electrical conductivity contents of all the 
other dumpsites except that of the Ojokondo dumpsite (Appendix 36). 
 
4.6.1.4 Total organic carbon 
The bimonthly values of total organic carbon of soil samples ranged from 2.28 to 8.07 
% (4.76±0.49 %) at the Ojokondo dumpsite, 0.95 to 5.56 % (2.89±0.41 %) at the 
Olodo dumpsite, 1.81 to 15.21 % (4.98±1.03 %) at the Moniya dumpsite, 1.14 to 5.39 
% (3.19±0.39 %) at the Idi Ope dumpsite, 0.27 to 6.14 % (2.27±0.43 %) at the 
Oremeji dumpsite and 0.85 to 3.36 % (2.01±0.26 %) at the control site (Balewa)  
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Figure 4.30: Bimonthly variation of particle size distribution values of soil from 
dumpsites (a) Sand       (b) Silt      (c) Clay  
 
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(Figure 4.31c; Appendix 32). 
One way analysis of variance showed that the total organic carbon in the soil samples 
were significantly different at P<0.05 (Appendix 35). Duncan’s multiple range tests 
also showed that the total organic carbon of the soil from the Moniya dumpsite was 
significantly different from total organic carbon contents of all the other dumpsites 
except that of the Ojokondo dumpsite at P<0.05 (Appendix 36).  
 
4.6.1.5 Total organic matter 
The bimonthly values of total organic matter ranged from 3.94 to 13.95 % (8.23±0.86 
%) at the Ojokondo dumpsite, 1.64 to 9.61 % (4.99±0.71 %) at the Olodo dumpsite, 
3.13 to 26.30 % (8.62±1.78 %) at the Moniya dumpsite, 1.97 to 9.32 % (5.51±0.68 %) 
at the Idi Ope dumpsite, 0.47 to 10.62 % (3.92±0.75 %) at the Oremeji dumpsite and 
1.47 to 5.81 % (3.47±0.44 %) at the control site (Balewa) (Figure 4.31d; Appendix 
32). 
One way analysis of variance and Duncan’s multiple tests showed the same trend as 
those of the total organic carbon contents of the soil samples (Appendices 35 and 36).  
 
4.6.2 Bimonthly variation of anions of soil samples from dumpsites 
The range and mean values of the anions of soil samples from the dumpsites are 
shown in Appendix 33. Details are shown in Appendices 37 to 42. 
 
4.6.2.1 Nitrate – nitrogen 
Nitrate – nitrogen was not detected in the soil sample from the Idi Ope dumpsite in 
June 2008, but it was detected in all other soil samples. It was not detected in the soil 
samples from the control site (Balewa) and the Olodo dumpsite in October 2008 and 
October 2009. In April 2009, it was not detected in the soil from the Olodo and Idi 
Ope dumpsites. In June 2009, it was not detected in the control soil (Balewa) and the 
soil samples from Ojokondo and Oremeji dumpsites but it was detected in the soil 
samples from Olodo, Moniya and Idi Ope dumpsites with values of 152.02 mg/kg, 
1659.46 mg/kg and 547.58 mg/kg respectively. In February and August 2009, nitrate 
– nitrogen was not detected in the soil samples from the Idi Ope dumpsite and the 
control site (Balewa) respectively. In December 2009, it was not detected in the soil 
samples from the control site (Balewa), Olodo and Idi Ope dumpsites but it was  
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Figure 4.31: Bimonthly variation of physico-chemical values of soil from 
dumpsites (a) pH        (b)  EC       (c) TOC  (d) TOM  
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detected in the soil samples from Ojokondo, Moniya and Oremeji dumpsites with the 
values of 898.70 mg/kg, 592.02 mg/kg and 547.58 mg/kg respectively. In February 
2010, it was not detected in the soil samples from the control site (Balewa) and Idi 
Ope dumpsite (Figure 4.32a; Appendix 33). 
One way analysis of variance showed that the nitrate – nitrogen contents in the soil 
samples were not significantly different at P<0.05 (Appendix 35).  
 
4.6.2.2 Sulphate - sulphur 
In April 2008, the control site was not sampled. Sulphate - sulphur was present in all 
other sites except its non-occurrence in the soil sample from Moniya dumpsite. 
However, in June 2008, sulphate – sulphur was not detected in soil samples except in 
the soil sample from the Oremeji dumpsite with a value of 1.63 mg/kg. In August 
2008, it was present in all soil samples except the sample from the Olodo dumpsite. In 
October 2008, it was not detected in the samples from the control site (Balewa) and 
the Oremeji dumpsite. In December 2008, it was not present in the soil samples from 
the control site, Olodo and Oremeji dumpsites but it was detected in the soil samples 
from Ojokondo, Moniya and Idi Ope dumpsites with values of 1.63 mg/kg, 12.5 
mg/kg and 2.88 mg/kg respectively (Figure 4.32b; Appendices 37 to 42). 
In February 2009, sulphate – sulphur was present in all soil samples except the 
samples from the control site (Balewa) and the Idi Ope dumpsite. In April 2009, it 
was also present in all soil samples except the samples from the Idi Ope and Oremeji 
dumpsites. In June 2009, it was not detected in the soil samples from the control site, 
Olodo and Idi Ope dumpsites but it was detected in the soil samples from Ojokondo, 
Moniya and Oremeji dumpsites with the values of 1.63 mg/kg, 1.63 mg/kg and 4.38 
mg/kg respectively. In August 2009, sulphate – sulphur was detected in all soil 
samples except the soil sample from the control site. In October 2009, it was also 
present in all soil samples except the samples from the Idi Ope and the Oremeji 
dumpsites. In December 2009, it was not detected in the soil samples from Olodo, 
Moniya and Idi Ope dumpsites but it was detected in the soil samples from the control 
site, Ojokondo and Oremeji dumpsites with values of 7.13 mg/kg, 9.75 mg/kg and 
7.13 mg/kg respectively. In February 2010, it was not detected in the soil samples 
from Olodo and idi Ope dumpsites (Figure 4.32b; Appendices 37 to 42). 
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One way analysis of variance showed that the sulphate - sulphur contents in the soil 
samples were not significantly different at P<0.05 (Appendix 35). 
 
4.6.3 Bimonthly variation of cations of soil samples from dumpsites 
The range and mean values of the cations of soil samples from the dumpsites are 
shown in Appendix 33. Details are shown in Appendices 37 to 42. 
 
4.6.3.1 Phosphorus 
The bimonthly contents of phosphorus in the soil samples ranged from  89.88 to 
165.76 mg/kg (113.75±6.18 mg/kg) at the Ojokondo dumpsite, 14.00 to 157.92 mg/kg 
(100.24±14.55 mg/kg) at the Olodo dumpsite, 79.24 to 170.80 mg/kg (120.05±8.54 
mg/kg) at the Moniya dumpsite, 82.04 to 150.08 mg/kg (118.79±7.55 mg/kg) at the 
Idi Ope dumpsite, 40.04 to 176.12 mg/kg (109.36±10.62 mg/kg) at the Oremeji 
dumpsite and 55.72 to 150.80 mg/kg (99.10±10.05 mg/kg) at the control site (Balewa) 
(Figure 4.32c). 
One way analysis of variance showed that the phosphorus contents in the soil samples 
were not significantly different at P<0.05 (Appendix 35). 
 
4.6.3.2 Calcium  
The bimonthly calcium contents in the soil samples ranged from 28637.20 to 
72330.80 mg/kg (47644.85±4666.11 mg/kg) at the Ojokondo dumpsite, 4216.40 to 
56716.20 mg/kg (32268.59±5456.36 mg/kg) at the Olodo dumpsite, 1478.10 to 
46474.80 mg/kg (23441.63±4143.81 mg/kg) at the Moniya dumpsite, 9663.90 to 
27032.30 mg/kg (19609.60±1650.37 mg/kg) at the Idi Ope dumpsite, 549.70 to 
37203.00 mg/kg (15615.00±3733.82 mg/kg) at the Oremeji dumpsite and  2398.40 to 
33688.20 mg/kg (16740.00±2560.00 mg/kg) at the control site (Balewa) (Figure 
4.32d). 
One way analysis of variance showed that the calcium contents in the soil samples 
were significantly different at P<0.05 (Appendix 35). Duncan’s multiple range tests 
also showed that the calcium contents of the soil from the Ojokondo dumpsite was 
significantly different from the calcium contents of all samples (Appendix 36). 
 
 
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2-
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Figure 4.32: Bimonthly variation of some anions and cations values of soil from 
- 2-
dumpsites (a) NO3  - N        (b)  SO4  - S       (c) P  (d) Ca 
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4.6.3.3 Magnesium 
The bimonthly magnesium contents in the soil samples ranged from 418.33 to 
9312.90 mg/kg (3589.57±822.83mg/kg) at the Ojokondo dumpsite, 508.97 to 4919.40 
mg/kg (2216.05±371.58mg/kg) at the Olodo dumpsite, 460.80 to 8343.30 mg/kg 
(2045.60±613.03mg/kg) at the Moniya dumpsite, 652.56 to 2432.70 mg/kg 
(1503.54±166.68mg/kg) at the Idi Ope dumpsite, 92.69 to 6919.20 mg/kg 
(2452.88±532.25mg/kg) at the Oremeji dumpsite and 584.70 to 3312.60 mg/kg 
(1438.35±239.72mg/kg) at the control site (Figure 4.33a). 
One way analysis of variance showed that the magnesium contents in the soil samples 
were not significantly different at P<0.05 (Appendix 35). However, Duncan’s 
multiple range tests showed that the magnesium contents of the soil samples from 
Ojokondo dumpsite was significantly different from the soil samples from Idi Ope 
dumpsite and control (Balewa) (Appendix 36). 
 
4.6.3.4 Sodium 
The bimonthly values of sodium in the soil samples ranged from 300.00 to 2700.00 
mg/kg (1277.55±219.82 mg/kg) at the Ojokondo dumpsite, 400.00 to 11400.00 mg/kg 
(2790.30±1266.13 mg/kg) at the Olodo dumpsite, 100.00 to 1800.00 mg/kg 
(708.83±151.51 mg/kg) at the Moniya dumpsite, 200.00 to 2400.00 mg/kg 
(686.08±65.62 mg/kg) at the Idi Ope dumpsite, 600.00 to 1700.00 mg/kg 
(1046.25±98.66 mg/kg) at the Oremeji dumpsite and 300.00 to 5500.00 mg/kg 
(1170.00±490.59 mg/kg) at the control site (Figure 4.33b; Appendix 33). 
One way analysis of variance showed that the sodium contents in the soil samples 
were not significantly different at P<0.05 (Appendix 35). However, Duncan’s 
multiple range tests showed that the sodium contents of the soil from the Olodo 
dumpsite was significantly different from the sodium contents of the other soil 
samples (Appendix 36). 
 
4.6.3.5 Potassium 
The bimonthly potassium contents in the soil samples at the Ojokondo, Olodo, 
Moniya, Idi Ope dumpsites, Oremeji and control site (Balewa) ranged from 1330 to 
6830 mg/kg (3239.17±476.18 mg/kg), 1130 to 6930 mg/kg (2962.27±614.76 mg/kg), 
530 to 18630 mg/kg (3157.42±1428.50 mg/kg), 1130 to 3822 mg/kg (2132.08±202.53 
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mg/kg), 1030 to 9730 mg/kg (3630.33±737.37 mg/kg) and 1030 to 8330 mg/kg 
(2030.00±708.05 mg/kg) respectively (Figure 4.33c; Appendix 33). 
One way analysis of variance showed that the potassium contents in the soil samples 
were not significantly different at P<0.05 (Appendix 35). 
 
4.6.3.6 Cation exchange capacity (CEC) 
The bimonthly values of cation exchange capacity of the soil samples ranged from  
173.93 to 449.70 Cmol/kg (274.34±27.87 Cmol/kg) at the Ojokondo dumpsite, 40.48 
to 358.00 Cmol/kg (201.53±35.19 Cmol/kg) at the Olodo dumpsite, 13.39 to 348.63 
Cmol/kg (146.63±29.04 Cmol/kg) at the Moniya dumpsite, 64.78 to 159.71 Cmol/kg 
(119.64±10.17 mg/kg) at the Idi Ope dumpsite 20.34 to 256.56 Cmol/kg 
(113.19±22.12 Cmol/kg) at the Oremeji dumpsite and 23.67 to 188.14 Cmol/kg 
(113.89±17.53 Cmol/kg) at the control site (Figure 4.33d).  
One way analysis of variance showed that the cation exchange capacities of the soil 
samples were significantly different at P<0.05 (Appendix 35). The cation exchange 
capacity of the soil samples from Ojokondo dumpsite was significantly different from 
those of the other soil samples except Olodo dumpsite at P<0.05 (Appendix 36). 
 
4.6.4 Bimonthly variation of trace and heavy metals of soil samples from 
dumpsites 
The range and mean values of the trace and heavy metals of soil samples from the 
dumpsites are shown in Appendix 34. Details are shown in Appendices 37 to 42. 
 
4.6.4.1 Iron 
The bimonthly values of iron in the soil samples ranged from 17407.30 to 59319.10 
mg/kg (38586.58±3677.56 mg/kg) at the Ojokondo dumpsite, 17555.20 to 28703.80 
mg/kg (20882.10±1187.06 mg/kg) at the Olodo dumpsite, 9284.20 to 47007.70 mg/kg 
(26343.13±3115.56 mg/kg) at the Moniya dumpsite, 11741.20 to 54270.10 mg/kg 
(27167.73±3893.89 mg/kg) at the Idi Ope dumpsite, 14434.00 to 80639.50 mg/kg 
(45208.21±5938.85 mg/kg) at the Oremeji dumpsite and 16698.40 to 41540.50 mg/kg 
(26401.13±2695.83 mg/kg) at the control site (Balewa) (Figure 4.34a). 
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NOTE: Blank spaces indicated that the control site (Tafawa Balewa Hall) was 
not sampled in the months of April and June, 2008. Other blank spaces indicated 
that Mg, Na, K and CEC were not detected in the samples. 
 
 
Figure 4.33: Bimonthly variation of cations values and cation exchange 
capacities of soil from dumpsites (a) Mg     (b) Na   (c) K       (d) CEC 
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One way analysis of variance showed that the iron contents in the soil samples were 
significantly different at P<0.05 (Appendix 35). Duncan’s multiple range tests also 
showed that the iron contents of the soil from the Ojokondo and Oremeji dumpsites 
were significantly different from the iron contents of all other soil samples but not 
different from each other at P<0.05 (Appendix 36). 
 
4.6.4.2 Manganese 
The bimonthly values of manganese in the soil samples ranged 206.53 to 2799.60 
mg/kg (1408.03±232.14 mg/kg), 492.80 to 847.00 mg/kg (681.98±38.23 mg/kg), 
205.51 to 798.60 mg/kg (535.04±54.33 mg/kg), 265.00 to 903.30 mg/kg 
(548.68±51.70 mg/kg), 195.50 to 1380.40 mg/kg (622.46±103.61 mg/kg) and 549.50 
to 6178.00 mg/kg (1338.24±606.74 mg/kg), at the Ojokondo, Olodo, Moniya, Idi 
Ope, Oremeji dumpsites and the control site respectively (Figure 4.34b). 
One way analysis of variance showed that the manganese contents in the soil samples 
were significantly different at P<0.05 (Appendix 35). Duncan’s multiple range tests 
also showed that the manganese contents of the soil from the Ojokondo dumpsite and 
control site (Balewa) were significantly different from the manganese contents of all 
soil samples but not different from each other at P<0.05 (Appendix 36). 
 
4.6.4.3 Copper 
The bimonthly values of copper in the soil samples ranged from 37.80 to 239.88 
mg/kg (147.79±19.64 mg/kg) at the Ojokondo dumpsite, 47.70 to 273.00 mg/kg 
(92.02±19.42 mg/kg) at the Olodo dumpsite, 9.00 to 227.78 mg/kg (69.92±16.10 
mg/kg) at the Moniya dumpsite, 47.40 to 231.90 mg/kg (85.74±15.36 mg/kg) at the 
Idi Ope, 16.51 to 479.60 mg/kg (133.52±36.40 mg/kg) at the Oremeji dumpsite and 
12.20 to 36.20 mg/kg (23.84±2.54 mg/kg) at the control site (Figure 4.34c). 
One way analysis of variance showed that the copper contents in the soil samples 
were significantly different at P<0.05 (Appendix 35). Duncan’s multiple range tests 
also showed that the copper contents of the soil from the control site was significantly 
different from the copper contents of all samples except those of Moniya and Idi Ope 
dumpsites (Appendix 36). 
 
 
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4.6.4.4  Zinc 
The bimonthly values of zinc in the soil samples ranged from 304.30 to 5458.90 
mg/kg (2022.04±428.24 mg/kg) at the Ojokondo dumpsite, 48.50 to 1636.00 mg/kg 
(352.11±167.50 mg/kg) at the Olodo dumpsite, 66.00 to 871.30 mg/kg (438.60±95.06 
mg/kg) at the Moniya dumpsite, 92.70 to 944.10 mg/kg (466.89±86.94 mg/kg) at the 
Idi Ope dumpsite, 66.60 to 2683.60 mg/kg (688.50±238.20 mg/kg) at the Oremeji 
dumpsite and 43.10 to 113.60 mg/kg (76.90±5.80 mg/kg) at the control site (Figure 
4.34d). 
One way analysis of variance showed that the zinc contents in the soil samples were 
significantly different at P<0.05 (Appendix 35). Duncan’s multiple range tests also 
showed that the zinc contents of the soil from the Ojokondo dumpsite was 
significantly different from the zinc contents of all samples (Appendix 36).  
 
4.6.4.5 Lead 
The bimonthly values of lead in the soil samples ranged from 150.30 to 552.60 mg/kg 
(319.97±38.14 mg/kg) at the Ojokondo dumpsite, 23.60 to 143.80 mg/kg 
(87.91±11.96 mg/kg) at the Olodo dumpsite, 10.60 to 310.10 mg/kg (116.06±26.41 
mg/kg) at the Moniya dumpsite, 83.40 to 410.00 mg/kg (232.51±40.13 mg/kg) at the 
Idi Ope dumpsite, 51.38 to 1081.00 mg/kg (265.37±94.46 mg/kg) at the Oremeji 
dumpsite and 0.40 to 84.90 mg/kg (51.71±8.88 mg/kg) at the control site (Figure 
4.35a). 
One way analysis of variance showed that the lead contents in the soil samples were 
significantly different at P<0.05 (Appendix 35). Duncan’s multiple range tests also 
showed that the lead contents of the soil from the Ojokondo dumpsite was 
significantly different from lead contents of other soil samples except those of the Idi 
Ope and Oremeji dumpsites at P<0.05 (Appendix 36). 
 
4.6.4.6 Cadmium 
In April 2008, the control site was not sampled. Cadmium was not present in all soil 
samples except the soil from the Oremeji dumpsite with a value of 3.00 mg/kg. 
However, in June 2008, cadmium was present in all soil samples except the soil from 
the Idi Ope dumpsite (Figure 4.35b). 
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control site (Tafawa Balewa Hall) was not sampled. 
 
Figure 4.34: Bimonthly variation of some trace and heavy metals of soil from 
dumpsites   (a) Fe            (b) Mn                       (c) Cu                        (d)   Zn 
 
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The bimonthly values of cadmium in the soil samples ranged from 0.19 to 26.50 
mg/kg (8.78±2.14 mg/kg) at the Ojokondo dumpsite, 0.90 to 5.83 mg/kg (2.10±0.44 
mg/kg) at the Olodo dumpsite, 0.70 to 36.00 mg/kg (5.77±3.09 mg/kg) at the Moniya 
dumpsite, 1.60 to 6.50 mg/kg (3.27±0.46 mg/kg) at the Idi Ope dumpsite, 0.40 to 7.90 
mg/kg (4.15±0.64 mg/kg) at the Oremeji dumpsite and 0.60 to 2.40 mg/kg (1.26±0.15 
mg/kg) at the control site (Figure 4.35a). 
One way analysis of variance showed that the cadmium contents in the soil samples 
were significantly different at P<0.05 (Appendix 35). Duncan’s multiple range tests 
also showed that the cadmium contents of the soil samples from the Ojokondo 
dumpsite were significantly different from others except those of Moniya and Oremeji 
dumpsites (Appendix 36). 
 
4.6.4.7 Nickel 
In June 2008, nickel was present in all soil samples except the soil from the Olodo 
dumpsite (Figure 4.35c). The bimonthly values of nickel in the soil samples ranged 
from 11.90 to 1217.70 mg/kg (144.78±107.35 mg/kg) at the Ojokondo dumpsite, 8.70 
to 169.00 mg/kg (33.49±17.01 mg/kg) at the Olodo dumpsite, 13.30 to 30.38 mg/kg 
(18.47±1.60 mg/kg) at the Moniya dumpsite, 9.77 to 34.70 mg/kg (18.91±2.39 mg/kg) 
at the Idi Ope dumpsite, 8.00 to 53.90 mg/kg (28.99±4.03 mg/kg) at the Oremeji 
dumpsite and 10.00 to 22.20 mg/kg (18.91±2.39 mg/kg) at the control site (Figure 
4.35c). 
One way analysis of variance showed that the nickel contents in the soil samples were 
not significantly different at P<0.05 (Appendix 35). 
 
4.6.4.8 Chromium 
In April 2008, the control site was not sampled; chromium was not present in all other 
soil samples. So also in June 2008, the control site was not sampled, chromium was 
present in all soil samples except the soil from the Ojokondo dumpsite. In October 
2009, chromium was also present in all soil samples except the soil from the Moniya 
dumpsite (Figure 4.35d). The bimonthly values of chromium in the soil samples 
ranged from 16.00 to 1137.40 mg/kg (137.60±111.11 mg/kg) at the Ojokondo 
dumpsite, 2.80 to 21.80 mg/kg (12.15±1.86 mg/kg) at the Olodo dumpsite, 8.50 to 
24.20 mg/kg (16.35±1.74 mg/kg) at the Moniya dumpsite, 7.13 to 100.40 mg/kg 
 
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(23.51±8.10 mg/kg) at the Idi Ope dumpsite, 5.70 to 42.20 mg/kg (28.98±4.25 mg/kg) 
at the Oremeji dumpsite and 3.10 to 30.70 mg/kg (17.65±2.75 mg/kg) at the control 
site (Figure 4.35d). 
One way analysis of variance showed that the chromium contents in the soil samples 
were not significantly different from one another at P<0.05 (Appendix 35). 
 
4.7 Result of analysis of groundwater samples close to the streams 
4.7.1 Bimonthly variation of physico-chemical characteristics of groundwater 
samples close to the streams 
The well close to the Odinjo stream was not sampled in the months of March and May 
2008. However, the range and mean values of the physico-chemical characteristics of 
the well close to the Gege stream (sampled from March, 2008 to January, 2010) and 
also the Odinjo stream (sampled from July, 2008 to January, 2010) are shown in 
Appendix 43. Details are shown in Appendices 47 and 48. 
 
4.7.1.1 Hydrogen ion concentration (pH) 
The bimonthly values of the pH of groundwater samples ranged from 6.39 to 8.15 
(7.29±0.16) at the well close to the Gege stream and 6.11 to 7.92 (7.08±0.17) at the 
well close to the Odinjo stream (Figure 4.36a; Appendix 43). 
T-test showed that the pH values of the two wells were not significantly different 
from each other at P<0.05 (Appendix 46). 
 
4.7.1.2 Biochemical oxygen demand (BOD) 
The bimonthly biochemical oxygen demand (BOD) values of the wells close to the 
Gege and Odinjo streams ranged from 34.84 to 102.62 mg/l (62.76±7.79 mg/L) and 
27.23 to 115.39 mg/L (73.02±8.91 mg/L) respectively (Figure 4.36b; Appendix 43). 
T-test showed that the biochemical oxygen demand (BOD) values of the two wells 
were not significantly different from each other at P<0.05 (Appendix 46). 
 
 
 
 
 
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40000 NL - NESREA LIMIT (164 mg/kg) 
30000 
20000 
10000 
0 NL 
-10000 
50 NL - NESREA LIMIT (0.35 mg/kg) 
40 
30 
20 
10 
0 NL 
-10  
1500 NL - NESREA LIMIT (70 mg/kg) 
1000 
500 
0 NL 
-500 
1400 NL - NESREA LIMIT (100 mg/Kg) 
1200 
1000 
800 
600 
400 NL 
200 
0 
-200 
Sampling Year/Month 
Ojokondo Olodo Moniya Idi Ope Oremeji Balewa 
 
NOTE: Blank spaces indicated that the control site (Tafawa Balewa Hall) was 
not sampled in the months of April and June, 2008. Other blank spaces indicated 
that Cd,  Ni and Cr were not detected in the samples. 
 
Figure 4.35: Bimonthly variation of some trace and heavy metals of soil from 
dumpsites    (a) Pb            (b) Cd                       (c) Ni                        (d)  Cr 
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UN Cr (mg/Kg) Ni mg/Kg Pb (mg/kg) Cd (mg/kg) IVERSITY OF IBADAN LIBRARY
 
4.7.1.3 Chemical oxygen demand (COD) 
The range of bimonthly values of chemical oxygen demand (COD) detected at the 
well close to the Gege stream was from 104.65 to 340.00 mg/L (220.91±24.59 mg/L) 
and that of the well close to the Odinjo stream was from 84.61 to 361.18 mg/L 
(230.22±28.22 mg/L) (Figure 4.36c; Appendix 43). 
T-test showed that the chemical oxygen demand (COD) values of the two wells were 
not significantly different from each other at P<0.05 (Appendix 46). 
 
4.7.1.4 Total dissolved solids (TDS) 
The bimonthly range of 528.00 to 1350.00 mg/L (1080.83±77.34 mg/L) of the total 
dissolved solids was observed at the well close to the Gege stream while the range of 
346.00 to 688.00 mg/L (553.7±29.63 mg/L) was observed at the well close to the 
Odinjo stream (Figure 4.36d; Appendix 43). 
T-test showed that the total dissolved solids of the two wells were significantly 
different from each other at P<0.05 (Appendix 46). 
 
4.7.1.5 Electrical conductivity (EC) 
The bimonthly ranges of 880 to 2250 µS/cm (1952.75±111.31 µS/cm) and 814.00 to 
1148.00 µS/cm (970.40±35.12 µS/cm) of electrical conductivity (EC) were observed 
at the wells close to the Gege and Odinjo streams respectively (Figure 4.37a; 
Appendix 43). 
T-test showed that the electrical conductivity (EC) values of the two wells were 
significantly different from each other at P<0.05 (Appendix 46). 
 
4.7.1.6 Total alkalinity 
The bimonthly ranges of total alkalinity detected at the wells close to the Gege and 
Odinjo streams were from 176.40 to 660.80 mg/L (403.70±46.36 mg/L) and 161.70 to 
468.86 mg/L (318.65±29.59 mg/L) respectively (Figure 4.37b; Appendix 43). 
T-test showed that the total alkalinity values of the two wells were not significantly 
different from each other at P<0.05 (Appendix 46). 
 
 
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10 Highest desirable level - 7.0 -8.5 
8 Maximum permissible level - 6.5 - 9.2 
6 
4 
2 
0 
150 
100 
50 
0  
500 
400 
300 
200 
100 
0  
1600 
1400 
1200 
1000 
800 
600 
400 
200 
0 
Sampling Year/Month 
Gege Odinjo 
 
NOTE: Blank spaces indicated that the well close to the Odinjo stream was not 
sampled in the months of March and May, 2008. 
 
Figure 4.36: Bimonthly variation of physico-chemical characteristics of 
groundwater samples close to streams (a) pH     (b) BOD    (c) COD        (d)  TDS 
 148 
UN TDS (mg/L) COD (mg/L) BOD (mg/L) pH IVERSITY OF IBADAN LIBRARY
 
4.7.2   Bimonthly variation of anions of groundwater samples close to the streams 
The range and mean values of the anions of groundwater samples close to the streams 
are shown in Appendix 44. Details are shown in Appendices 47 and 48. 
 
4.7.2.1 Chloride 
The bimonthly ranges of chloride content were from 178.19 to 541.08 mg/L 
(279.55±26.65 mg/L) and 79.52 to 210.93 mg/L (123.38±11.76 mg/L) at the wells 
close to the Gege and Odinjo streams respectively (Figure 4.37c; Appendix 44). 
T-test showed that the chloride contents of the two wells were significantly different 
from each other at P<0.05 (Appendix 46). 
 
4.7.2.2 Phosphate - phosphorus 
In July 2008, November 2009 and January 2010, phosphate - phosphorus was not 
detected at the well close to the Odinjo stream while in March 2009, November 2009 
and January 2010, it was not also detected at the well close to the Gege stream 
(Appendices 47 and 48).  
The bimonthly ranges observed were from 40.82 to 2822.86 mg/L (571.44±331.21 
mg/L) and 12.24 to 308.57 mg/L (129.37±41.14 mg/L) at the wells close to the Gege 
and Odinjo streams respectively (Figure 4.37d; Appendix 44). 
T-test showed that the phosphate - phosphorus contents of the two wells were 
significantly different from each other at P<0.05 (Appendix 46). 
 
4.7.2.3 Nitrate - nitrogen 
The bimonthly values of nitrate - nitrogen detected at the wells close to the Gege and 
Odinjo streams ranged from 25.36 to 43.84 mg/L (36.41±1.94 mg/L) and 4.67 to 
39.37 mg/L (24.47±4.00 mg/L) respectively (Figure 4.38a; Appendix 44). 
T-test showed that the nitrate - nitrogen contents of the two wells were significantly 
different from each other at P<0.05 (Appendix 46). 
 
 
 
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4.7.2.4 Sulphate - sulphur 
The bimonthly values of sulphate – sulphur ranged from 1762.50 to 4129.17 mg/L 
(2733.64±179.68 mg/L) and 1580.00 to 2512.50 mg/L (2018.63±108.03 mg/L) at the 
wells close to the Gege and Odinjo streams respectively (Figure 4.38b; Appendix 44). 
T-test showed that the sulphate - sulphur contents of the two wells were significantly 
different from each other at P<0.05 (Appendix 46). 
 
4.7.3  Bimonthly variation of cations of groundwater samples close to the streams 
The range and mean values of the cations of groundwater samples close to the streams 
are shown in Appendix 44. Details are shown in Appendices 47 and 48. 
 
4.7.3.1 Calcium 
The bimonthly values of calcium detected at the wells close to the Gege and Odinjo 
streams were 8.4118 to 104.0770 mg/l (49.23±10.76 mg/L) and 2.7289 to 82.2160 
mg/L (27.45±12.71 mg/L) respectively (Figure 4.38c; Appendix 44). 
T-test showed that the calcium contents of the two wells were not significantly 
different from each other at P<0.05 (Appendix 46). 
 
4.7.3.2 Magnesium 
The bimonthly magnesium values ranged from 25.5179 to 123.2960 mg/L 
(42.31±9.08 mg/L) and 10.5590 to 36.4667 mg/L (23.32±4.91 mg/L) at the wells 
close to Gege and Odinjo streams respectively (Figure 4.38d; Appendix 44). 
T-test showed that the magnesium contents of the two wells were not significantly 
different from each other at P<0.05 (Appendix 46). 
 
4.7.4 Bimonthly variation of trace and heavy metals of groundwater samples 
close to the streams  
The range and mean values of trace and heavy metals of groundwater samples close to 
the streams are shown in Appendix 45. Details are shown in Appendices 47 and 48. 
 
 
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3000 
2000 
1000 
0 
800 
600 
400 
200 
0 
600     MPL 
500 HDL - Highest desirable level (200 mg/L) 
400 MPL - Maximum permissible level (600 mg/L) 
300 
200 HDL 
100 
0 
3500 
3000 
2500 
2000 
1500 
1000 
500 
0 
-500 
Sampling Year/Month 
Gege Odinjo  
NOTE: Blank spaces indicated that the well close to the Odinjo stream was not 
2-
sampled in the months of March and May, 2008 and PO4 -P was not detected in 
samples from the two wells in November, 2009 and January, 2010. 
 
 
Figure 4.37: Bimonthly variation of some physico-chemical characteristics and 
some anions of groundwater samples close to streams (a) EC    (b) Total 
alkalinity    (c) Chloride        (d)  Phosphate – phosphorus 
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50 MPL- 50 mg/L 
HDL -A 4 5 mg/L 
40 
30 
20 
10 
0 
5000 HDL - Highest desirable level (200 mg/Kg) 
MPL - Maximum permissible level (400 mg/L) 
4000 
3000 
2000 
1000 
AM PL 
HDL 
0 
200 MPL 
HDL - Highest desirable level (75 mg/L) 
150 MPL - Maximum permissible level (200 mg/L)  
100 
HDL 
50 
0 
-50 
150 MPL 
130 HDL - Highest desirable level (30mg/L) 
110 MPL - Maximum permissible level (150 mg/L) 
90 
70 
50 
30 HDL 
10 
-10 
Sampling Year/Month 
Gege Odinjo 
NOTE: Blank spaces indicated that the well close to the Odinjo stream was not 
sampled in the months of March and May, 2008 and Ca and Mg were not 
detected in samples from the two wells in September and November, 2009 and 
January, 2010. 
 
Figure 4.38: Bimonthly variation of some anions and some cations of 
- 2-
groundwater samples close to streams (a) NO3  - N    (b) SO4  - S   (c) Ca  (d)  Mg 
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4.7.4.1 Iron 
Iron was not detected in the well water sample close to Gege stream in the month of 
May 2008. It was also not detected in the well water sample close to Odinjo stream in 
the months of July to November 2008 and January 2009 (Appendices 47 and 48). 
The bimonthly ranges observed were from 0.33 to 4.37 mg/L (0.92±0.39 mg/L) and 
0.30 to 6.30 mg/L (2.57±2.11 mg/L) at the wells close to the Gege and Odinjo streams 
respectively (Figure 4.39a; Appendix 45). 
T-test showed that the iron contents of the two wells were significantly different from 
each other at P<0.05 (Appendix 46). 
 
4.7.4.2 Manganese 
Manganese was not detected in the well water sample close to the Gege stream in the 
months of September 2009, November 2009 and January 2010 (Appendices 47 and 
48). 
The bimonthly ranges observed were from 0.04 to 0.36 mg/L (0.19±0.06 mg/L) and 
0.01 to 0.21 mg/L (0.10±0.04 mg/L) at the wells close to the Gege and Odinjo streams 
respectively (Figure 4.39b; Appendix 45). 
T-test showed that the manganese contents of the two wells were not significantly 
different from each other at P<0.05 (Appendix 46). 
 
4.7.4.3 Copper 
Throughout the sampling period, copper was not detected in the well water sample 
close to the Odinjo stream. However, it was detected in the well water close to the 
Gege stream in the months of March, May and September 2008; and January 2009 
with values of 0.2438 mg/L, 0.0710 mg/L, 0.0469 mg/L and 0.1580 mg/L respectively 
(Figure 4.39c; Appendices 47 and 48). 
 
4.7.4.4 Zinc 
Zinc was not detected in the groundwater sample close to Gege stream in the months 
of May 2008 and January 2010 (Appendices 47 and 48). 
The bimonthly values observed at the groundwater sample close to the Gege stream 
ranged from 0.004 to 9.61 mg/L (1.38±1.05 mg/L) while that of the well close to the 
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Odinjo stream was from 0.004 to 4.654 mg/L (1.05±0.67 mg/L) (Figure 4.39d; 
Appendix 45). 
T-test showed that the zinc contents of the two wells were not significantly different 
from each other at P<0.05 (Appendix 46). 
 
4.7.4.5 Lead 
Lead was not detected in the groundwater sample close to Gege stream in the months 
of March 2008; July 2008 and 2009; May 2009; September 2009; November 2009 
and January 2010. It was not also detected in the groundwater sample close to Odinjo 
stream in the months of July 2008 and 2009; November 2008 and May 2009 
(Appendices 47 and 48). 
However, the bimonthly ranges observed were from 0.05 to 0.25 mg/L (0.17±0.04 
mg/L) and 0.16 to 0.19 mg/L (0.17±0.01 mg/L) at the wells close to the Gege and 
Odinjo streams respectively (Figure 4.40a; Appendix 45). 
T-test showed that the lead contents of the two wells were significantly different from 
each other at P<0.05 (Appendix 46). 
 
4.7.4.6 Cadmium   
Cadmium was not detected in the groundwater sample close to Gege stream in the 
months of May 2008; July 2008 and 2009; September 2008; November 2008 and 
January 2009. It was not also detected in the groundwater sample close to Odinjo 
stream in the months of September 2008, November 2008 and January 2009. 
However, the bimonthly ranges observed were from 0.02 to 0.06 mg/L (0.04±0.01 
mg/L) and 0.08 to 0.09 mg/L (0.08±0.004 mg/L) at the wells close to the Gege and 
Odinjo streams respectively (Figure 4.40b; Appendix 45). 
 
4.7.4.7 Nickel 
Nickel was not detected in the groundwater sample close to Gege stream in the 
months of March 2008, July 2008, May 2009, September 2008 and 2009; November 
2008 and January 2010. It was not also detected in the groundwater sample close to 
 
 
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7 HDL - Highest desirable level (0.1 mg/L) 
MPL - Maximum permissible level (1.0 mg/L) 
5 
3 
1 MPL 
HDL 
-1 
-3 
0.5 MPL 
HDL - Highest desirable level (0.05 mg/L) 
0.4 
MPL - Maximum permissible level (0.5 mg/L) 
0.3 
0.2 
0.1 
HDL 
0 
-0.1 
1.5 MPL 
1.3 HDL - Highest desirable level (0.05 mg/L) 
1.1 MPL - Maximum permissible level (1.5 mg/L) 
0.9  
0.7 
0.5 
0.3 
0.1 HDL 
-0.1 
15 MPL 
13 HDL - Highest desirable level (5.0 mg/L) 
11 MPL - Maximum permissible level (15.0 mg/L) 
9 
7 
5 HDL 
3 
1 
-1 
-3 
Sampling Year/Month 
Gege Odinjo 
 
NOTE: Blank spaces indicated that the well close to the Odinjo stream was not 
sampled in the months of March and May, 2008 and Fe, Mn, Cu and Zn were 
not detected in samples from the two wells. 
 
Figure 4.39: Bimonthly variation of some trace and heavy metals of groundwater 
samples close to streams  (a) Fe         (b) Mn      (c) Cu       (d)  Zn 
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UN Cu (mg/L) Mn (mg/L) Zn (mg/L) Fe (mg/L) IVERSITY OF IBADAN LIBRARY
 
Odinjo stream in the months of July 2008 and 2009; and May 2009 (Appendices 47 
and 48). 
However, the bimonthly nickel ranges observed were from 0.02 to 0.07 mg/L 
(0.04±0.02 mg/L) and 0.002 to 0.08 mg/L (0.04±0.04 mg/L) at the wells close to the 
Gege and Odinjo streams respectively (Figure 4.40c; Appendix 45). 
T-test showed that the nickel contents of the two wells were not significantly different 
from each other at P<0.05 (Appendix 46). 
 
4.7.4.8 Chromium   
During the sampling period, chromium was detected once in each of the groundwater 
samples. 0.0849 mg/L was detected at the well from the Gege stream in September, 
2008 while 0.0020 mg/L was detected at the well from the Odinjo stream in March, 
2009 (Figure 4.40d; Appendices 47 and 48). 
 
4.8 Result of analysis of groundwater samples around the dumpsites 
4.8.1 Bimonthly variation of physico-chemical characteristics of groundwater 
samples around the dumpsites 
The range and mean values of the physico-chemical characteristics of groundwater 
samples around the dumpsites are shown in Appendix 49. Details are shown in 
Appendices 54 to 60.  
 
4.8.1.1 Hydrogen ion concentration (pH) 
The bimonthly values of the pH of groundwater samples around the dumpsites ranged 
from  6.48 to 7.35 (6.8±0.08) at the well before the Ojokondo dumpsite, 6.70 to 8.00 
(7.16±0.13) at the well after the Ojokondo dumpsite, 6.30 to 7.64 (6.94±0.12) at the 
well close to the Olodo dumpsite, 5.19 to 6.76 (6.08±0.11) at the well close to the 
Moniya dumpsite, 6.14 to 7.80 (7.05±0.15) at the well close to the Idi-Ope dumpsite, 
6.11 to 7.20 (6.71±0.10) at the well close to the Oremeji dumpsite and 6.63 to 7.90 
(7.05±0.14) at the well at the control site (Balewa) (Figure 4.41a; Appendix 49). 
One way analysis of variance showed that the pH values of the groundwater samples 
close to the dumpsites were significantly different from one another at P<0.05 
(Appendix 52). Duncan’s multiple range tests also showed that the pH of the 
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0.4 
0.3 
0.2 
0.1 
0 
0.12 
0.1 
0.08 
0.06 
0.04 
0.02 
0 
0.1 
0.05 
0 
-0.05 
0.1 
0.08 
0.06 
0.04 
0.02 
0 
Sampling Year/Month 
Gege Odinjo 
 
NOTE: Blank spaces indicated that the well close to the Odinjo stream was not 
sampled in the months of March and May, 2008 and Pb, Cd, Ni and Cr were not 
detected in samples from the two wells. 
 
Figure 4.40: Bimonthly variation of some trace and heavy metals of groundwater 
samples close to streams  (a) Pb         (b) Cd      (c) Ni       (d) Cr 
157 
 
UN Cr (mg/L) Ni (mg/L) Cd (mg/L) Pb (mg/L) IVERSITY OF IBADAN LIBRARY
 
well close to the Moniya dump dumpsite was significantly different from the pH of all 
the other samples (Appendix 53).    
 
4.8.1.2  Biochemical oxygen demand (BOD) 
The bimonthly values of the biochemical oxygen demand (BOD) of groundwater 
samples around the dumpsites ranged from 25.03 to 67.39 mg/L (47.06±4.51 mg/L) at 
the well before the Ojokondo dumpsite, 32.02 to 138.89 (54.25±9.63 mg/L) at the 
well after the Ojokondo dumpsite, 27.14 to 60.05 mg/L (42.05±2.53 mg/L) at the well 
close to the Olodo dumpsite, 30.88 to 60.28 mg/L (39.38±2.67 mg/L) at the well close 
to the Moniya dumpsite, 18.16 to 140.62 (47.39±9.94 mg/L) at the well close to the 
Idi-Ope dumpsite, 31.02 to 93.36  (51.60±5.65 mg/L) at the well close to the Oremeji 
dumpsite and 22.21 to 74.10 (44.65±5.85) at the well at the  control site (Balewa) 
(Figure 4.41b; Appendix 49). 
One way analysis of variance showed that the biochemical oxygen demand values of 
the groundwater samples close to the dumpsites were not significantly different from 
one another at P<0.05 (Appendix 52). 
 
4.8.1.3  Chemical oxygen demand (COD) 
The bimonthly values of the chemical oxygen demand (COD) of groundwater 
samples around the dumpsites ranged from 78.22 to 208.61 mg/L (147.92±12.09 
mg/L) at the well before the Ojokondo dumpsite, 102.62 to 246.26 mg/L 
(161.21±15.18 mg/L) at the well after the Ojokondo dumpsite, 88.26 to 186.16 mg/L 
(137.94±7.57 mg/L) at the well close to the Olodo dumpsite, 98.62 to 217.86 mg/L 
(141.83±10.59 mg/L) at the well close to the Moniya dumpsite, 60.46 to 420.00 mg/L 
(173.44±33.40 mg/L) at the well close to the Idi-Ope dumpsite, 96.16 to 320.00 mg/L 
(178.13±20.55 mg/L) at the well close to the Oremeji dumpsite and 72.86 to 226.12 
mg/L (134.27±15.49) at the well at the  control site (Balewa) (Figure 4.41c; Appendix 
49). 
One way analysis of variance showed that the chemical oxygen demand of the 
groundwater samples close to the dumpsites were not significantly different from one 
another at P<0.05 (Appendix 52). 
 
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4.8.1.4 Total dissolved solids (TDS) 
The bimonthly values of the total dissolved solids (TDS) of groundwater samples 
around the dumpsites ranged from 260.00 to 523.00 mg/L (357.67±25.19 mg/L) at the 
well before the Ojokondo dumpsite, 846.00 to 1370.00 mg/L (1104.17±62.78 mg/L) 
at the well after the Ojokondo dumpsite, 102.00 to 1015.00 mg/L (334.50±67.60 
mg/L) at the well close to the Olodo dumpsite, 96.00 to 1177.00 mg/L (264.17±84.53 
mg/L) at the well close to the Moniya dumpsite, 167.00 to 1004.00 mg/L 
(284.50±66.34 mg/L) at the well close to the Idi-Ope dumpsite, 153.00 to 1123.00 
mg/L (688.50±75.16 mg/L) at the well close to the Oremeji dumpsite and 53.80 to 
280.00 mg/L (191.08±21.01 mg/L) at the well at the  control site (Balewa) (Figure 
4.41d; Appendix 49). 
One way analysis of variance showed that the groundwater samples around the 
various dumpsites were significantly different from one another at P<0.05 (Appendix 
52). Duncan’s multiple range tests also showed that the total dissolved solids of the 
well after the Ojokondo dumpsite and the well close to the Oremeji dumpsite were 
significantly different from the total dissolved solids of all the other samples. They 
were also different from each other at P<0.05 (Appendix 53).    
 
4.8.1.5 Electrical conductivity (EC) 
The bimonthly values of the electrical conductivity (EC) of groundwater samples 
around the dumpsites ranged from 516.00 to 873.00 µS/cm (650.25±29.06 µS/cm) at 
the well before the Ojokondo dumpsite, 1510.00 to 2380.00 (2030.00±90.33 µS/cm) 
at the well after the Ojokondo dumpsite, 255.00 to 1693.00 µS/cm  (597.08±107.94 
µS/cm) at the well close to the Olodo dumpsite, 197.50 to 1963.00 µS/cm 
(467.88±137.80 µS/cm) at the well close to the Moniya dumpsite, 325.00 to 1674.00 
µS/cm (510.42±106.50 µS/cm) at the well close to the Idi-Ope dumpsite, 255.00 to 
1870.00 µS/cm (1271.50±130.16 µS/cm) at the well close to the Oremeji dumpsite 
and 89.70 to 468.00 (348.77±38.32 µS/cm) at the well at the  control site (Balewa), 
(Figure 4.42a; Appendix 49). 
One way analysis of variance of electrical conductivity showed that the samples from 
the various dumpsites were significantly different from one another at P<0.05 
(Appendix 52). Duncan’s multiple range tests showed the same trend with total 
dissolved solids of the samples (Appendix 53). 
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10 Highest desirable level - 7.0 - 8.5 
8 Maximum permissible level 6.5 - 9.2 
6 
4 
2 
0 
200 
150 
100 
50 
0 
500 
400 
300 
200 
100 
0 
1600 
1400 
1200 
1000 
800 
600 
400 
200 
0 
Sampling Year/Month 
Ojokondo (Before Dump) Ojokondo (After Dump) Olodo 
Moniya Idi Ope Oremeji 
Balewa 
 
Figure 4.41: Bimonthly variation of physico-chemical characteristics of 
groundwater samples close to dumpsites (a) pH     (b) BOD   (c) COD   (d) TDS 
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4.8.1.6  Total alkalinity 
The bimonthly values of the total alkalinity of groundwater samples from dumpsites 
ranged from 85.05 to 344.75 mg/L (203.30±19.64 mg/L) at the well before the 
Ojokondo dumpsite, 233.28 to 558.50 mg/L (400.92±26.98 mg/L) at the well after the 
Ojokondo dumpsite, 113.80 to 317.17 mg/L (190.67±19.85 mg/L) at the well close to 
the Olodo dumpsite, 25.92 to 218.30 mg/L (84.16±14.44 mg/L) at the well close to 
the Moniya dumpsite 81.00 to 265.50 mg/L (163.88±18.10 mg/L) at the well close to 
the Idi-Ope dumpsite, 193.60 to 589.50 mg/L (353.64±39.06 mg/L) at the well close 
to the Oremeji dumpsite and 91.80 to 258.56 mg/L (171.42±15.79 mg/L) at the well at 
the  control site (Balewa) (Figure 4.42b; Appendix 49). 
One way analysis of variance showed that the total alkalinity values of the 
groundwater samples from the various dumpsites were significantly different from 
one another at P<0.05 (Appendix 52). Duncan’s multiple range tests showed that the 
total alkalinity values observed at the well close to the Moniya dumpsite was 
significantly different from all other samples (Appendix 53).   
 
4.8.2 Bimonthly variation of anions of groundwater samples from the 
dumpsites 
The range and mean values of the anions of groundwater samples around the 
dumpsites are shown in Appendix 50. Details are shown in Appendices 54 to 60. 
 
4.8.2.1 Chloride 
The bimonthly values of the chloride contents of groundwater samples from 
dumpsites ranged from 34.40 to 101.26 mg/L (66.86±5.92 mg/L) at the well before 
the Ojokondo dumpsite, 105.51 to 471.83 mg/L (287.77±29.75 mg/L) at the well after 
the Ojokondo dumpsite, 30.56 to 84.02 mg/L (55.48±4.39 mg/L) at the well close to 
the Olodo dumpsite, 18.35 to 60.85 mg/L (37.74±4.36 mg/L) at the well close to the 
Moniya dumpsite, 29.54 to 56.02 mg/L (38.78±2.15 mg/L) at the well close to the Idi-
Ope dumpsite, 90.88 to 261.87 mg/L (156.57±16.59 mg/L) at the well close to the 
Oremeji dumpsite and 16.13 to 47.81 mg/L (32.80±3.32 mg/L) at the well at the  
control site (Balewa) (Figure 4.42c; Appendix 49). 
 
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One way analysis of variance showed that the samples from the various dumpsites 
were significantly different from one another at P<0.05 (Appendix 52). Duncan’s 
multiple range tests showed that the chloride content observed at the well after the 
Ojokondo dumpsite and the well close to the Oremeji dumpsite were significantly 
different from the chloride contents of all the other samples. They were also 
significantly different from each other at P<0.05 (Appendix 53). 
 
4.8.2.2 Phosphate-phosphorus 
During the sampling months of June 2008, April 2009 and June 2009, phosphate-
phosphorus was not detected in all groundwater samples. In August 2008, it was 
detected at the wells before and after the Ojokondo dumpsite with same value of 4.08 
mg/L. In August 2009, phosphate-phosphorus was not detected at the well at the 
control site and the well at the Moniya dumpsite; the same occurrence was observed 
in October 2009 with the non-detection at the Idi Ope well inclusive. In December 
2009, it was not observed in all groundwater samples except that of Olodo well with a 
value of 33.33 mg/L. In February 2010, it was observed at the Idi Ope well and the 
well before the Ojokondo dumpsite with the values of 85.71 mg/L and 4.76 mg/L 
respectively (Figure 4.42d; Appendix 49). 
One way analysis of variance showed that the samples from the various dumpsites 
were not significantly different from one another at P<0.05 (Appendix 52). 
 
4.8.2.3 Nitrate-nitrogen 
During the sampling period in October 2009, nitrate-nitrogen was not detected at the 
wells at the Idi Ope, Oremeji and control site. In December 2009, it was not also 
detected at the wells before the Ojokondo dumpsite, Idi Ope dumpsite and the control 
site (Figure 4.41a; Appendices 54 to 60). 
The bimonthly values observed ranged from 3.2 to 38.38 mg/L (27.99±3.19 mg/L), 
21.17 to 42.09 mg/L (33.64±1.88 mg/L), 13.42 to 42.03 mg/L (25.10±2.32 mg/L), 
20.50 to 42.42 mg/L (31.25±2.12 mg/L), 8.46 to 25.6 mg/L (16.12±1.82 mg/L), 11.84 
to 38.07 mg/L (23.70±2.30 mg/L) and 4.14 to 25.11 mg/L (19.22±2.89 mg/L) at the 
wells before the Ojokondo dumpsite, after the Ojokondo dumpsite, close to the Olodo 
dumpsite, close to the Moniya dumpsite, close to the Idi Ope dumpsite, close to the 
Oremeji dumpsite and at the control site (Figure 4.43a).  
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3000 
2500 
2000 
1500 
1000 
500 
0 
800 
600 
400 
200 
0 
600 MPL 
HDL - Highest desirable level (200 mg/Kg) 
500 MDL - Maximum permissible level (600 mg/Kg) 
400 
300 
200 HD
100 
0 
400 
300 
200 
100 
0 
-100 
Sampling Year/Month 
Ojokondo (Before Dump) Ojokondo (After Dump) Olodo 
Moniya Idi Ope Oremeji  
NOTE: Blank spaces indicated that the control site (Tafawa Balewa Hall) was 
not sampled in the months of April and June, 2008. Other blank spaces indicated 
that phosphate-phosphorus was not detected in the samples. 
 
Figure 4.42: Bimonthly variation of some physico-chemical characteristics and 
some anions of groundwater samples close to streams (a) EC    (b) Total 
alkalinity    (c) Chloride        (d)  Phosphate - phosphorus 
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UN PO 2-4  - P (mg/L) Cl- (mg/L) T.Alk (mg/L) EC (µS/cm) IVERSITY OF IBADAN LIBRARY
 
One way analysis of variance showed that the nitrate-nitrogen contents of the samples 
from the various dumpsites were significantly different from one another at P<0.05 
(Appendix 52). Duncan’s multiple range tests showed that the nitrate - nitrogen 
content observed at the well close to the Idi-Ope dumpsite and the well at the control 
site were significantly different from those of all the other samples but they were not 
different from each other at P<0.05 (Appendix 53). 
 
4.8.2.4 Sulphate-sulphur 
In October 2008 and December 2009, sulphate-sulphur was not detected at the well 
close to the Moniya dumpsite (Appendix 57). The bimonthly values ranged from 
1425.00 to 3195.83 mg/L (2240.21±179.07 mg/L) at the well before the Ojokondo 
dumpsite, 1216.67 to 4016.67 mg/L (2540.44±276.97 mg/L) at the well after the 
Ojokondo dumpsite, 656.30 to 1756.25 mg/L (1130.20±113.86 mg/L) at the well 
close to the Olodo dumpsite, 25.00 to 608.33 mg/L (212.71±57.28 mg/L) at the well 
close to the Moniya dumpsite, 987.50 to 2690.00 mg/L (1772.16±138.74 mg/L) at the 
well close to the Idi-Ope dumpsite, 706.25 to 5431.82 mg/L (2989.84±395.59 mg/L) 
at the well close to the Oremeji dumpsite and 704.17 to 4110.00 mg/L 
(1929.63±319.88 mg/L) at the well at the  control site (Balewa) (Figure 4.43b; 
Appendix 50). 
One way analysis of variance showed that the groundwater samples close to the 
various dumpsites were significantly different from one another at P<0.05 (Appendix 
52). Duncan’s multiple range tests also showed that the sulphate – sulphur of the well 
close to the Moniya dumpsite was significantly different from the sulphate – sulphur 
of all the other samples (Appendix 53).    
 
4.8.3 Bimonthly variation of cations of groundwater samples close to the 
dumpsites 
The range and mean values of the cations of groundwater samples from the dumpsites 
are shown in Appendix 50. Details are shown in Appendices 54 to 60. 
 
4.8.3.1 Calcium 
In June, August and December 2008, calcium was not detected at the well close to the 
Moniya dumpsite. So also in December 2008 and February 2009, it was not detected 
 
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at the wells before the Ojokondo dumpsite and at the control site (Balewa) (Figure 
4.43c; Appendices 54, 57 and 60). The bimonthly values ranged from 1.38 to 43.16 
mg/L (18.18±4.41 mg/L) at the well before the Ojokondo dumpsite, 14.64 to 165.56 
mg/L (64.70±18.22 mg/L) at the well after the Ojokondo dumpsite, 3.18 to 71.4 mg/L 
(33.08±8.28 mg/L) at the well close to the Olodo dumpsite, 13.36 to 73.27 mg/L 
(38.25±9.00 mg/L) at the well close to the Moniya dumpsite, 3.57 to 53.53 mg/L 
(30.17±6.80 mg/L) at the well close to the Idi-Ope dumpsite, 12.22 to 155.99 mg/L 
(67.73±19.30 mg/L) at the well close to the Oremeji dumpsite and 5.01 to 74.74 mg/L 
(41.64±8.89 mg/L) at the well at the  control site (Balewa) (Figure 4.43c; Appendix 
50). 
One way analysis of variance showed that the calcium contents of the samples close 
to the various dumpsites were significantly different from one another at P<0.05 
(Appendix 52). Duncan’s multiple range tests also showed that the calcium content of 
the well before the Ojokondo dumpsite and the well at the Oremeji dumpsite were 
significantly different from each other but not different from the other samples 
(Appendix 53).    
 
4.8.3.2 Magnesium 
The bimonthly values of magnesium contents of groundwater samples close to the 
dumpsites ranged from 20.30 to 36.24 mg/L (30.19±1.75 mg/L) at the well before the 
Ojokondo dumpsite, 35.78 to 47.51 mg/L (40.79±1.44 mg/L) at the well after the 
Ojokondo dumpsite, 7.97 to 38.26 mg/L (20.58±3.87 mg/L) at the well close to the 
Olodo dumpsite, 8.08 to 37.74 mg/L (22.60±3.90 mg/L) at the well close to the 
Moniya dumpsite, 6.32 to 35.37 mg/L (16.69±3.24 mg/L) at the well close to the Idi-
Ope dumpsite, 7.36 to 73.10 mg/L (37.18±5.75 mg/L) at the well close to the Oremeji 
dumpsite and 9.34 to 38.35 mg/L (21.43±4.12 mg/L) at the well at the  control site 
(Balewa) (Figure 4.43d; Appendix 50). 
One way analysis of variance showed that the magnesium contents of the samples 
from the various dumpsites were significantly different from one another at P<0.05 
(Appendix 52). Duncan’s multiple range tests also showed that the magnesium 
contents of the wells before the Ojokondo dumpsite, after the Ojokondo dumpsite and 
close to the Oremeji dumpsite were significantly different from other samples but not 
significantly different from one another at P<0.05 (Appendix 53). 
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6000 
HDL - Highest desirable level  (200 mg/L) 
5000 
MPL - Maximum permissible level (400 mg/L) 
4000 
3000 
2000 
1000 MPL 
0 HDL 
-1000 
200 MPL 
HDL - Highest desirable level  (75 mg/L) 
150 MPL - Maximum permissible level (200 mg/L) 
100 
HDL 
50 
0 
-50 
 
 
150 MPL 
HDL - Highest desirable level (30 mg/L) 
100 MPL - Maximum permissible level (150 mg/L) 
50 
HDL 
0 
Sampling Year/Month 
Ojokondo (Before Dump) Ojokondo (After Dump) Olodo 
Moniya Idi Ope Oremeji 
NOTE: Blank spaces indicated that the control site (Tafawa Balewa Hall) was 
not sampled in the months of April and June, 2008. Other blank spaces indicated 
that Ca and Mg were not detected in the samples. 
 
Figure 4.43: Bimonthly variation of some anions and some cations of 
- 2-
groundwater samples close to dumpsites (a) NO3  - N (b) SO4  - S (c) Ca  (d)  Mg 
166 
 
U SO 2-N 4  - S (mg/L) Mg (mg/L) Ca (mg/L) IVERSITY OF IBADAN LIBRARY
 
4.8.4 Bimonthly variations of trace and heavy of groundwater samples close to 
the dumpsites 
The range and mean values of the trace and heavy metals of groundwater samples 
from the dumpsites are shown in Appendix 51. Details are shown in Appendices 54 to 
60. 
 
4.8.4.1 Iron 
In April 2008, iron was not detected in all groundwater samples. In June 2008, it was 
not also detected in all groundwater samples except the one close to the Oremeji 
dumpsite with a value of 0.3727 mg/L. In August and October 2008, iron was not 
detected at the wells close to the Moniya dumpsite and the one close to the Olodo 
dumpsite. In December 2008, it was not detected in the groundwater close to the Idi 
Ope dumpsite (Figure 4.44a; Appendices 54 to 60). 
One way analysis of variance showed that the iron content in the groundwater 
samples from the various dumpsites were not significantly different from one another 
at P<0.05 (Appendix 52). 
 
4.8.4.2 Manganese 
Manganese was not detected in the groundwater sample after the Ojokondo dumpsite 
in October 2008. It was not also detected in the groundwater sample at the control site 
in April and June 2009 (Figure 4.44b; Appendices 55 and 60). The bimonthly values 
of manganese contents of groundwater samples close to the dumpsites ranged from 
0.02 to 1.32 mg/L (0.38±0.14 mg/L) at the well before the Ojokondo dumpsite, 0.15 
to 2.00 mg/L (0.52±0.25 mg/L) at the well after the Ojokondo dumpsite, 0.07 to 0.33 
mg/L (0.20±0.03 mg/L) at the well close to the Olodo dumpsite, 0.02 to 1.27 mg/L 
(0.23±0.15 mg/L) at the well close to the Moniya dumpsite, 0.08 to 0.43 mg/L 
(0.28±0.05 mg/L) at the well close to the Idi-Ope dumpsite, 0.13 to 11.98 mg/L 
(2.48±1.24 mg/L) at the well close to the Oremeji dumpsite and 0.06 to 0.25 mg/L 
(0.18±0.04 mg/L) at the well at the  control site (Balewa) (Figure 4.44b; Appendices 
54 to 60). 
One way analysis of variance showed that the manganese contents of the groundwater 
samples close to the various dumpsites were significantly different from one another 
at P<0.05 (Appendix 52). Duncan’s multiple range tests also showed that the 
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manganese contents of the well close to the Oremeji dumpsite was significantly 
different from those of all the other samples (Appendix 53).  
 
4.8.4.3 Copper 
In April 2008, copper was not detected in all groundwater samples except the one 
before the Ojokondo dumpsite and the one close to the Idi Ope dumpsite with values 
of 0.099 mg/L and 0.062 mg/L respectively. In June 2008 it was not detected in the 
groundwater samples before and after the Ojokondo dumpsite and also the well close 
to the Olodo dumpsite. In August 2008, it was not detected in the samples from the 
well close to the Idi Ope dumpsite and the well close to the Oremeji dumpsite. In 
October 2008, it was not detected in the sample from the control well (Balewa) and 
the well close to the Oremeji dumpsite. In December 2008, it was not detected in the 
samples from the well after the Ojokondo dumpsite, the well close to the Moniya 
dumpsite and the well close to the Idi Ope dumpsite (Figure 4.44c; Appendices 54 to 
60). 
In February 2009, copper was detected in all groundwater samples except from the 
control site (Balewa). However, in April 2009, it was not detected in all groundwater 
samples. In June 2009, it was detected only in the samples from the well before the 
Ojokondo dumpsite and the one close to the Oremeji dumpsite with values of 0.026 
mg/L and 0.097 mg/L respectively. In August 2009, it was detected only in the 
samples from the Moniya well and the Oremeji well with values of 0.002 mg/L and 
0.007 mg/L respectively. In October 2009, it was only detected in the sample from the 
well before the Ojokondo dumpsite with a value of 0.019 mg/L. In December, it was 
detected at the Moniya well with a value of 0.075 mg/L and lastly, in February 2010, 
it was detected at the Olodo well with a value of 0.009 mg/L (Figure 4.44c; 
Appendices 54 to 60). 
One way analysis of variance showed that the copper content in the samples from the 
various dumpsites were not significantly different from one another at P<0.05 
(Appendix 52). 
 
4.8.4.4 Zinc 
Zinc was not detected in all groundwater samples in the month of April 2008. In June 
2008 it was not also detected in all samples except at the well after the Ojokondo 
 
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dumpsite and the well close to the Moniya dumpsite with the values of 0.0002 mg/L 
and 0.0475 mg/L respectively. In October 2008, February 2009, August 2009 and 
October 2009, zinc was not detected at the Idi Ope well, the well after the Ojokondo 
dumpsite, the well before the Ojokondo dumpsite and the well at the control site 
(Balewa) respectively.  In December 2009, it was not detected in all samples except 
that from the control site (Balewa) and the well close to the Moniya dumpsite with 
values of 0.0020 mg/L and 3.246 mg/L respectively. In addition, in February 2010, 
zinc was not detected in all samples except from the wells close to the Oremeji and 
Olodo dumpsites with the values of 0.0960 mg/L and 0.2920 mg/L respectively 
(Figure 4.44d; Appendices 54 to 60). 
One way analysis of variance showed that the zinc contents of the samples from the 
various wells were significantly different from one another at P<0.05 (Appendix 52). 
Duncan’s multiple range tests also showed that zinc contents of the well after the 
Ojokondo dumpsite and the well at the Idi Ope dumpsite were significantly different 
from the zinc contents of all the other samples but not significantly different from 
each other (Appendix 53).   
 
4.8.4.5 Lead 
Lead was not detected in all groundwater samples in April and June 2008 except at 
the ones close to the Olodo and Moniya dumpsites respectively with values of 0.1960 
mg/L and 0.2625 mg/L respectively. In October 2008, it was only in the sample from 
the well close to the Idi Ope dumpsites that lead was not detected (Appendices 56 to 
58). 
In April 2009, lead was not detected in all groundwater samples except those close to 
the Oremeji and Moniya dumpsites with values of 0.2100 mg/L and 0.2010 mg/L 
respectively. Furthermore, in June 2009, lead was detected in the well after the 
Ojokondo dumpsite, and the wells close to Idi Ope and Oremeji dumpsites with 
values of 0.0590 mg/L, 0.0200 mg/L and 0.2480 mg/L respectively. In addition, in 
August 2009, lead was discovered in the well after the Ojokondo dumpsite – 0.0340 
mg/L; the well close to the Moniya dumpsite – 0.1990 mg/L; and the well close to the 
Oremeji dumpsite – 0.0950 mg/L. In October 2009, it was detected in the well before 
the Ojokondo dumpsite – 0.0030 mg/L, the well after the Ojokondo dumpsite – 
0.0010 mg/L and the well close to the Oremeji dumpsite – 0.0930 mg/L. In December 
 
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15 HDL - Highest desirable level  (0.1 mg/L) 
MPL - Maximum permissible level (1.0 mg/L) 
10 
5 
MPL 
0 HDL 
A 
-5 
15 
HDL - Highest desirable level - 0.05 mg/L 
MPL - Maximum permissible level - 0.5 mg/L 
10 
5 
0 
-5 
1.5 MPL 
HDL -Highest desirable level - 0.05 mg/L 
1 MPL - Maximum permissible level - 1.5 
0.5 
0 A HDL 
-0.5 
 
20 HDL -Highest desirable level - 5 mg/L 
15 MPL - Maximum permissible level - 15 mg/L MPL 
10  
5 HDL 
0 
-5 
A 
Sampling Year/Month 
Ojokondo (Before Dump) Ojokondo (After Dump) Olodo 
Moniya Idi Ope Oremeji 
Balewa  
NOTE: Blank spaces indicated that the control site (Tafawa Balewa Hall) was 
not sampled in the months of April and June, 2008. Other blank spaces indicated 
that Fe, Mn, Cu and Zn were not detected in the samples. 
 
Figure 4.44: Bimonthly variation of some trace and heavy metals of groundwater 
samples close to dumpsites (a) Fe    (b) Mn   (c) Cu  (d)  Zn 
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2008 and February 2010, lead was detected in the groundwater samples from the 
control site (Balewa) and Olodo dumpsite respectively with values of 0.1490 mg/L 
and 0.1990 mg/L respectively (Figure 4.45a; Appendices 54 to 60). 
One way analysis of variance showed that the lead contents in the wells close to the 
various dumpsites were not significantly different from one another at P<0.05 
(Appendix 52). 
 
4.8.4.6 Cadmium 
Cadmium was not detected in the sample from the well close to the Idi Ope dumpsite 
in April 2008. In June 2008, it was not detected in the groundwater samples close to 
the Olodo, Moniya and Oremeji dumpsites. In August 2008, it was detected in the 
groundwater sample from the Oremeji dumpsite with a value of 0.0147 mg/L. In 
October 2008, December 2008 and February 2009, cadmium was not detected in all 
groundwater samples (Figure 4.45b; Appendices 54 to 60). 
In April 2009, cadmium was not detected in the sample from the well before the 
Ojokondo dumpsite and the well close to the Olodo dumpsite. In December 2009 and 
February 2010, it was not detected in the well close to the Idi Ope dumpsite and the 
well after the Ojokondo dumpsite respectively (Figure 4.45b; Appendices 54 to 60). 
The bimonthly values of cadmium contents of groundwater samples close to the 
dumpsites ranged from 0.002 to 0.04 mg/L (0.02±0.01 mg/L) at the well before the 
Ojokondo dumpsite, 0.006 to 0.07 mg/L (0.04±0.01 mg/L) at the well after the 
Ojokondo dumpsite, 0.002 to 0.07 mg/L (0.04±0.01 mg/L) at the well close to the 
Olodo dumpsite, 0.004 to 0.04 mg/L (0.02±0.01 mg/L) at the well close to the Moniya 
dumpsite, 0.001 to 0.07 mg/L (0.03±0.01 mg/L) at the well close to the Idi-Ope 
dumpsite, 0.002 to 0.06 mg/L (0.02±0.01 mg/L) at the well close to the Oremeji 
dumpsite and 0.004 to 0.07 mg/L (0.03±0.01 mg/L) at the well at the  control site 
(Balewa) (Figure 4.45b; Appendices 54 to 60). 
One way analysis of variance showed that the cadmium contents in the samples from 
the various dumpsites were not significantly different from one another at P<0.05 
(Appendix 52). 
 
 
 
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4.8.4.7 Nickel 
Nickel was not detected in all groundwater samples in June 2008. In August 2008, it 
was not detected in the sample from the control site (Balewa). In October 2008, it was 
not detected in the samples from the well after the Ojokondo dumpsite and the well 
close to the Oremeji dumpsite. Furthermore, in April 2009, it was not detected in the 
samples from the wells close to the Olodo and at the control site. In June 2009, it was 
not detected in the samples from the Moniya and control site wells. In addition, in 
August 2009, it was not detected in samples from the well before the Ojokondo 
dumpsite, Idi Ope well and the control site (Figure 4.45c; Appendices 54 to 60). 
In October 2009, nickel was detected in the sample from the well after the Ojokondo 
dumpsite and the Oremeji well with values of 0.0590 mg/L and 0.0420 mg/L 
respectively. In December 2009, it was not detected in samples from the well before 
the Ojokondo dumpsite, the well at the Olodo dumpsite and the Idi Ope well. 
However, nickel was detected in February 2010 in the samples from the Idi Ope well 
and the control site with values of 0.0550 mg/L and 0.0590 mg/L respectively (Figure 
4.45c; Appendices 54 to 60). 
One way analysis of variance showed that the nickel contents in the wells close to the 
various dumpsites were not significantly different from one another at P<0.05 
(Appendix 52). 
 
4.8.4.8 Chromium 
Chromium was not detected in all samples in the months of October 2008, October 
2009, December 2009 and February 2010 (Figure 4.45d; Appendices 54 to 60). 
In June 2008, chromium was not detected in the samples from the Olodo, Moniya and 
Oremeji wells. In December 2008, it was detected in the sample from the control site 
with a value of 0.1292 mg/L. Furthermore, in February 2009, it was still detected in 
the sample from the well before the Ojokondo dumpsite and also the control site with 
values of 0.1369 mg/L and 0.1445 mg/L respectively. In addition, in April 2009, June 
2009 and August 2009, chromium was detected in the samples from Moniya well – 
0.0320 mg/L, Oremeji well – 0.0190 mg/L and Moniya well – 0.1100 mg/L 
respectively (Figure 4.45d; Appendices 54 to 60). 
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One way analysis of variance showed that the chromium contents in the samples from 
wells close to the various dumpsites were not significantly different from one another 
at P<0.05 (Appendix 52). 
 
4.9 Toxicity assays 
4.9.1 Earthworms’ toxicity assay 
4.9.1.1 Streams 
The result of the Eudrilus euginiae earthworms exposed to the soil from the streams’ 
banks is presented in Figure 4.46a and Appendix 61. 
The result of the earthworms’ toxicity test of the soil from the streams indicated that 
throughout the 96 hours, there was no mortality observed in the soils from Omi Adio 
stream and the control site (Awba stream) (that is, 0 % mortality).  
Mortality of earthworms increased with duration of exposure. During the first 24 
hours, no mortality (0 %) was observed in the soil from the Irefin stream, at 48 hours 
6.67 % mortality was recorded, at 72 hours 20 % mortality was recorded, and at 96 
hours, 30 % mortality was recorded. 
The earthworms exposed to the Gege soil had 10 % mortality during the first 24 
hours, 13.33 % at 48 hours, 13.33 % mortality still maintained at 72 hours, while there 
was 30 % mortality at 96 hours. 
The result of the toxicity assay of earthworms exposed to the Gbagi soil indicated that 
13.33 % mortality was recorded at 24 hours, 33.33 % at 48 hours, and 43.33 % at both 
72 and 96 hours. 
Mortality of earthworms exposed to Odinjo soil indicated that 13.33 % mortality was 
observed at both 24 and 48 hours, it increased to 20 % at 72 hours and 33.33 % at 96 
hours. 
 
4.9.1.2 Dumpsites 
The result of the Eudrilus euginiae earthworms exposed to the soil from the 
dumpsites is presented in Figure 4.46b and Appendix 62. 
The result of the earthworms’ toxicity test of the soil from the dumpsites indicated 
that throughout the 96 hours, there was no mortality observed in the soils from the 
Moniya dumpsite and the control site (Balewa). In all the other soil samples, mortality 
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0.8 
0.6 
0.4 
0.2 
0 
-0.2 
0.1 
0.08 
0.06 
0.04 
0.02 
0 
-0.02 
0.15 
0.1 
0.05 
0 
-0.05  
0.3 
0.2 
0.1 
0 
-0.1 
Sampling Year/Month 
Ojokondo (Before Dump) Ojokondo (After Dump) Olodo 
Moniya Idi Ope Oremeji 
Balewa 
 
NOTE: Blank spaces indicated that the control site (Tafawa Balewa Hall) was 
not sampled in the months of April and June, 2008. Other blank spaces indicated 
that Pb, Cd, Ni and Cr were not detected in the samples. 
 
Figure 4.45: Bimonthly variation of some trace and heavy metals of groundwater 
samples close to dumpsites (a) Pb    (b) Cd   (c) Ni  (d)  Cr 
 174 
UN Cd (mg/L) Cr (mg/L) Ni (mg/L) Pb  (mg/L) IVERSITY OF IBADAN LIBRARY
 
increased with duration of exposure. Highest mortality was observed in the 
earthworms exposed to the Ojokondo dumpsite. At 24 hours, 50 % mortality was 
recorded. It increased to 66.67 % at 48 hours, 73.33 % at 72 hours and 76.67 % at 96 
hours. 
Earthworms exposed to the soil from the Olodo dumpsite showed 22 % mortality at 
24 hours, 28 % at 48 hours, 52 % at 72 hours, and 66.67 % at 96 hours. 
The result of mortality observed in the earthworms exposed to the Idi Ope dumpsite 
indicated 20 %, 30 %, 40 % and 46.67 % mortalities at 24, 48, 72 and 96 hours 
respectively. 
Earthworms exposed to the soil from the Oremeji dumpsite maintained 20 % 
mortality form 24 hours to 72 hours, 30 % mortality was observed at 72 hours.   
 
4.9.2 Mayflies toxicity assay 
Mayflies’ mortality occurred in all test chambers except the control. The mortality 
was concentration-dependent. At 24 hours, the number of mortalities of mayflies 
exposed to 1.56 %, 3.125 %, 6.25 %, 12.5 %, 25 % and 50 % concentrations of Irefin 
stream were 0, 4, 8, 10, 14 and 30 respectively, while at 48 hours, the number of 
mortalities were 2, 6, 12, 18, 22 and 40 respectively. For 1.56 %, 3.125 %, 6.25 %, 
12.5 %, 25 % and 50 % concentrations of Gege stream, the number of mortalities at 
24 hours were 0, 2, 6, 16, 30 and 34 respectively, while at 48 hours the number of 
mortalities were 4, 6, 12, 24, 34 and 40 respectively. For 1.56 %, 3.125 %, 6.25 %, 
12.5 %, 25 % and 50 % concentrations of Gbagi stream, the number of mortalities at 
24 hours were 0, 0, 2, 4, 8 and 8 respectively, while at 48 hours, the number of 
mortalities were 2, 4, 4, 10, 12 and 18 respectively. At 24 hours, 4 mortalities each 
were recorded for 1.56 %, 3.125 %, 6.25 % and 12.5 % concentrations of Odinjo 
stream while 10 and 12 mortalities were recorded for 25 % and 50 % concentrations 
respectively; For 48 hours, 6, 4, 8, 10, 12 and 30 mortalities were recorded for 1.56 
%, 3.125 %, 6.25 %, 12.5 %, 25 % and 50 % concentrations respectively. At 24 hours, 
the number of mortalities of mayflies exposed to 1.56 %, 3.125 %, 6.25 %, 12.5 %, 25 
% and 50 % concentrations of Omi Adio stream were 6, 8, 8, 12, 14 and 16 
respectively, while at 48 hours, the number of mortalities were 8, 8, 10, 14, 18 and 20 
respectively. No mortality was recorded for 1.56 % and 3.125 % concentrations of 
Awba stream, 6.25 % and 12.5 % concentrations had 2 mortalities each, while 25 %  
 
 
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50 
45 
40 
35 
30 
25 24 Hours 
48 Hours 
20 
72 Hours 
15 
96 Hours 
10 
5 
0 
Gege Irefin Gbagi Odinjo Omi Awba 
stream 
Sampling Locations 
90 
80 
70 
60 
50 24 Hours 
40 48 Hours 
72 Hours 
30 
96 Hours 
20 
10 
0 
Ojokondo Olodo Moniya Idi Ope Oremeji Balewa 
Sampling Locations 
 
NOTE: Blank spaces indicated that no mortality was observed in the soil from 
Omi Adio, Awba stream, Moniya and Balewa 
 
Figure 4.46 
a): Effect of dumpsites' soil on eudrilus euginiae survival  
b): Effect of streams' soil on eudrilus euginiae survival  
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and 50 % concentrations had 4 and 6 mortalities respectively; at 48 hours the number 
of mortalities were 4, 6, 10, 12, 12 and 14 respectively (Figure 4.47; Appendix 63a).  
The 48hour LC50 values of the stream-water samples obtained using Probit method 
were 12.67 %, 8.63 %, 72.13 %, 33.32 %, 49.55 % and 181.07 % for Irefin, Gege, 
Gbagi, Odinjo, Omi Adio and Awba streams respectively (Appendix 63b). 
 
4.9.3  Tadpoles bioassay 
There was no death of tadpoles exposed to varying concentrations of stream water 
from Gbagi, Odinjo, Omi Adio and Awba. However, mortalities that occurred in 
Irefin and Gege stream water exposure to tadpoles were concentration-dependent. It 
was only at 100 % concentration of Irefin stream water that tadpoles’ mortality 
occurred; At 24 hours exposure, 10 mortalities occurred while 11 mortalities were 
maintained from 48 hours to 96 hours. Tadpoles exposed to Gege stream had 
mortalities at 50 % and 100 % concentrations. The mortalities recorded at 24 hours, 
48 hours, 72 hours and 96 hours of 50 % concentration were 11, 11, 13, 18 
respectively. At 100 % concentration, all the tapoles died (Table 4.5). The 96 hour 
LC50 of Gege stream water using Probit method was 53.59 % with 95% lower and 
higher confidence limits of 47.34 % and 60.66 % respectively (Appendix 64). 
 
4.9.4 Fish toxicity assay 
4.9.4.1 Clarias gariepinus frys toxicity assay 
Clarias gariepinus frys mortality occurred in all test chambers except the control. The 
mortality was concentration-dependent. For the frys exposed to the Irefin stream 
water: 36 mortalities were recorded in 6.25 % concentration from 24 hours to 72 
hours, while it was 37 at 96 hours; 37 mortalities were recorded in 12.5 % 
concentration from 24 hours to 72 hours, while it was 39 at 96 hours; for 25 % 
concentration, 38 mortalities were recorded at 24 hours to 72 hours, while 39 was 
recorded at 96 hours;  for 50 %concentration, 39 mortalities recorded from24 hours to 
72 hours, while 40 was recorded at 96 hours; for 100 % concentration, all the frys 
died during the first 24 hours (Appendix 65a; Figure 4.48a). For the frys exposed to 
Gege stream water: frys in 6.25 % concentration had 11, 17, 26 and 33 mortalities 
recorded at 24, 48, 72 and 96 hours respectively; 12.5 % concentration had 19, 30, 35 
and 38 mortalities recorded at 24, 48, 72 and 96 hours respectively; for 25 % 
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50 
40 20 50 Gbagi 
40 Irefin 30 Gege 15 
30 10 
20 
20 5 
10 10 
0 
0 0 
Concentration (%) Concentration (%) Concentration (%) 
24 hours 48 hours 24 hours 48 hours 24 hours 48 hours 
   
40 
Omi Adio Awba stream 
30 Odinjo 30 15 
20 
20 10 10 
10 0 5 
0 
0 
Concentration (%) 
Concentration (%) 
Concentration (%) 
24 hours 48 hours 24 hours 48 hours 
24 hours 48 hours    
 
Figure 4.47: Mortalities of Cloeon perkinsi’s larvae exposed to different concentrations of stream water 
178 
 
Number of mortalities Number of mortalities 
UNIVERSITYNumber of mortalities  O Number of Mortalities F IBADAN
Number of 
mortalities   Number ofL morItaBlities RARY
 
Table 4.5: Mortalities of tadpoles to different concentrations of Gege stream 
water 
Concentration Exposure Number of Concentration Exposure Number of 
  Duration Mortalities   Duration Mortalities 
  24 hours 11   24 hours 40 
            
  48 hours 11   48 hours 40 
50%     100%     
72 hours 13   72 hours 40 
           
   96 hours 18   96 hours 40 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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concentration, 39 mortalities were recorded at 24 hours, while 40 recorded at 48 
hours; for 50 % and 100 % concentrations, 40 mortalities each were recorded during 
the first 24 hours (Appendix 65a; Figure 4.48b). For the frys exposed to Gbagi stream 
water: frys in 6.25 % concentration had 17, 22, 25 and 30 mortalities recorded at 24, 
48, 72 and 96 hours respectively; 12.5 % concentration had 19, 25, 29 and 33 
mortalities recorded at 24, 48, 72 and 96 hours respectively; for 25 % concentration, 
23, 32, 34 and 37 mortalities were recorded at 24, 48, 72 and 96 hours respectively; 
for 50 % concentration, 29, 35, 37 and 39 mortalities were recorded at 24, 48, 72 and 
96 hours respectively; for 100% concentration, 30, 35, 38 and 40 mortalities were 
recorded at 24, 48, 72 and 96 hours respectively (Appendix 65a; Figure 4.48c). For 
the frys exposed to Odinjo stream water:  frys exposed to 6.25 % concentration had 35 
mortalities at 24 hours and 37 mortalities throughout 48 to 96 hours; frys in 12.5 % 
concentration had 38 mortalities all through 24 to 72 hours, while it increased to 39 at 
96 hours; frys exposed to 25 % concentration had 39 mortalities recorded all through 
24 to 96 hours; at both 50 % and 100 % concentrations, all the frys (that is, 40) died 
within 24 hours (Appendix 65a; Figure 4.48d).  For the frys exposed to Odinjo stream 
water: frys exposed to 6.25 % concentration had 34 mortalities throughout 24 to 72 
hours while all died (that is, 40) at 96 hours; for 12. 5 % concentration, 36, 38, 39 and 
40 mortalities were recorded at 24, 48, 72 and 96 hours respectively; for 25 % 
concentration, 38 mortalities were recorded fir 24 to 72 hours, while 40 mortalities 
was recorded at 96 hours; at both 50 % and 100 % concentrations, all the frys (that is, 
40) died within 24 hours (Appendix 65a; Figure 4.48e).  For the frys exposed to Awba 
stream water: frys exposed to 6.25 % concentration had 11, 13, 14 and 16 mortalities 
at 24, 48, 72 and 96 hours respectively; frys exposed to 12.5 % concentration had 18, 
22, 22 and 26 mortalities at 24, 48, 72 and 96 hours respectively; frys exposed to 25 
% concentration had 30 mortalities at 24 hours , while 38 mortalities were recorded 
throughout 48 to 96 hours; frys exposed to 50 % concentration had 34 mortalities 
recorded at 24 hours, while  40 mortalities was recorded at 48 hours, at 100 % 
concentration, 34 mortalities, while 40 mortalities was recorded at 48 hours 
(Appendix 65a; Figure 4.48f). 
The 96hour LC50 of all stream water obtained using trimmed Spearman-Karber 
method were 2.75 %, 0.8 %, 2.8 %, 0.79 % and 4.27 % for Irefin, Gege, Gbagi, 
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Odinjo and Awba streams respectively. The 96hour LC50 of the Omi Adio stream 
could not be calculated. However, the 72hour LC50 had 2.63 % (Appendix 65b).  
 
4.9.4.2 Clarias gariepinus fingerlings bioassay 
When fingerlings of Clarias gariepinus were exposed to different concentrations of 
test solutions, there was no mortality recorded in the exposure to the test solutions 
from Gbagi, Odinjo, Omi Adio streams and control. However, fish mortality occurred 
in test chambers of Irefin and Gege.  
In the test chambers containing the varying concentrations of Irefin contaminated 
samples, the following mortalities were recorded: fingerlings in 3.125 % 
concentration had 0, 12, 16 and 23 mortalities recorded at 24, 48, 72 and 96 hours 
respectively; 6.25 % concentration had 3, 13, 18 and 24 mortalities recorded at 24, 48, 
72 and 96 hours respectively; for 12.5 % concentration, 5, 13, 29 and 30 mortalities 
were recorded at 24, 48, 72 and 96 hours respectively; for 25 % concentration, 5, 15, 
22 and 34 mortalities were recorded at 24, 48, 72 and 96 hours respectively; for 50% 
concentration, 6, 19, 30 and 35 mortalities were recorded at 24, 48, 72 and 96 hours 
respectively; while at 100 % concentration, 7, 20, 35 and 40 mortalities were recorded 
at 24, 48, 72 and 96 hours respectively (Table 4.6). 
For fingerlings exposed to the varying concentrations of contaminated Gege stream 
samples, the following mortalities were recorded: fingerlings in 3.125 % 
concentration had 0, 5, 3 and 14 mortalities recorded at 24, 48, 72 and 96 hours 
respectively; 6.25 % concentration had 0, 9, 15 and 21 mortalities recorded at 24, 48, 
72 and 96 hours respectively; for 12.5 % concentration, 2, 12, 21 and 23 mortalities 
were recorded at 24, 48, 72 and 96 hours respectively; for 25 % concentration, 12, 19, 
29 and 33 mortalities were recorded at 24, 48, 72 and 96 hours respectively; for 50% 
concentration, 15, 32, 33 and 35 mortalities were recorded at 24, 48, 72 and 96 hours 
respectively; while at 100 % concentration, 35, 40, 40 and 40 mortalities were 
recorded at 24, 48, 72 and 96 hours respectively (Table 4.6). 
The 96hour LC50 of Gege and Irefin downstream contaminated water obtained using 
Probit method indicated that Gege downstream had 3.327 % with 95 % lower and 
higher confidence limits of 1.138 % and 5.765 % respectively while Irefin 
downstream had 5.624 with 95 % lower and higher confidence limits of 3.045 % and 
8.366 % respectively (Appendix 66).  
 
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CHECK FIGURE 4.48 IN GRAPHS FOR CHAPTOR FOUR 
 
 
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Table 4.6: Mortalities of Clarias gariepinus fingerlings to different concentrations of 
Gege and Irefin stream water samples 
 
            
  Mortalities    
Samples C oncentrations  24 hours 48 hours 72 hours 96 hours  
Irefin 3.125% 0 12 16 23  
6.25% 3 13 18 24  
 12.50% 5 13 29 30  
 25% 5 15 22 34  
 50% 6 19 30 35  
 100% 7 20 35 40  
Ge ge 3.125% 0 5 3 14  
6.25% 0 9 15 21  
 12.50% 2 12 21 23  
 25% 12 19 29 33  
 50% 15 32 33 35  
 100% 35 40 40 40  
  
       
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER FIVE 
DISCUSSION 
5.1 Earthworm diversity and abundance and relationship with soil factors 
Earthworms are among the most widespread invertebrate animals found mainly in the 
soils of grasslands, woodlands, scrublands and forest, they are diverse in forms and in 
behaviour, and could be aquatic or terrestrial in nature (Abimbola et al., 2013). 
Ecologically, they represent the dominant faunal biomass of the soil in many environments 
except the environments that are highly saline, moisture-limited or acidic (Edwards and 
Lofty, 1977; Lee, 1985). 
The abundance and species composition of earthworm fauna at a particular site, and also 
the preference, avoidance or activity of individual earthworms (that is, the behavior) in 
contact with a soil substrate can indicate the quality of the soil (Heinz-Christian et al., 
2011). They have been shown to be of great importance in soil fertility, soil improvement 
and soil amelioration (Paoletti, 1999). They influence soil characteristics because they 
participate in the construction and destruction of the soil particles, as well as in organic 
matter transfer (Lemtiri et al., 2014). The combinations of the ecological categories of 
earthworms together or individually are responsible for the maintenance of soil fertility 
(Bhadauria et al., 1997; Sinha et al., 2003; Bhadauria and Saxena, 2010). 
Epigeic earthworms feed on plant debris, therefore they are mostly responsible for 
breaking down complex organic residues and mineralize nutrients (Ojha and Devkota, 
2014).  Some epigeic species maintain shallow horizontal burrows (Lee, 1985; Francis 
and Fraser, 1998; Ernst et al., 2009). Anecic and epigeic earthworms increase water 
infiltration in soil (Zaller et al., 2011; Spurgeon et al., 2013). The lifestyle of epigeic 
species may likely explain their effects on water infiltration rates: Since they dwell on the 
surface, their activities may prevent the formation of a soil surface crust or low
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 permeability (Spurgeon et al., 2013); the production and degradation of their casts 
form stable microaggregates which are important for soil moisture regulation and 
therefore for water affinity and conductivity (Bottinelli et al., 2010); when they are 
exposed to adverse conditions such as drought or frost, they may burrow deeper into 
the soil, therefore forming temporary vertical burrows which may act as conduits for 
water flow (Spurgeon et al., 2013). 
Endogeic earthworms are known as “ecological engineers,’’ or “ecosystem 
engineers’’ because they live exclusively and build extensive nonpermanent burrows 
in the upper mineral layer of soil and mainly ingest mineral soil matter (Bhadauria 
and Saxena, 2010). They keep moving in the soil to feed on soil organic matter 
(Lavelle et al., 1997), they primarily consume soil in the upper layer of the mineral 
soil (Lemtiri et al., 2014) and they produce physical structures through which they 
can modify the availability or accessibility of a resource for other organisms (Jones et 
al., 1994). 
Anecic earthworms live near subsurface soil region (Ojha and Devkota, 2014). This 
life style helps to increase water infiltration in soil. They dig vertical burrows which 
are connected to the soil surface and therefore act as preferential pathways for water 
flow and gas diffusivity (Edwards et al., 1990; Clements et al., 1991; Capowiez et al., 
2009; Spurgeon et al., 2013). Their burrows make major contribution to soil 
macroporosity (Andriuzzi et al., 2015).  
The result of the abundance and composition of earthworms collected at the streams 
and dumpsites indicated that all the sites had Eudrilus euginiae being the most 
abundant except at the control site for streams (Awba stream) where Dichogaster 
modigliani was the most abundant.  
The occurrence of Alma millsoni at the bank of the streams’ control site (Awba 
stream) was due to the fact that this species of earthworms is found in marshy 
environment. They are limicolous (marsh dwellers) (Dedeke et al., 2010) and they 
thrive well in a less/non-polluted environment. Ojieze and Eghafona (2014 and 2015) 
also collected Alma millsoni from riverside of Okitipupa, Ondo state, Nigeria. Alma 
millsoni is found in the floodplain known to be high in nutrients such as phosphorus 
(Dedeke et al., 2010). Owa and Olojo (2003) reported that such limicolous 
environments where they are found are high in nutrients such as phosphorus, are 
referred to as fertile regions that are yearly renewed by alluvial deposits resulting 
 
 
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from annual floods. The presence of Alma millsoni in Awba stream might account for 
the high phosphate-phosphorus present in the streamwater in the month of January, 
2009; high potassium in the soil in the months of November, 2009 and January. 2010; 
and high sodium in all the three months that the earthworm was found. Dedeke et al. 
(2010) observed high phosphorus, potassium and sodium in Alma millsoni 
earthworms collected among banks of stream in Olabisi Onabanjo University, Ago-
Iwoye, Ijebu northeast area, southwest, Nigeria. They attributed the presence of these 
macrominerals to the marshy environment where the earthworms were collected. 
Eudrilus euginiae are epigeic earthworms that live in the uppermost moist soil litter 
layer and feeding mainly on organic matter of the soil (Sivasankari et al., 2014). They 
are generally referred to as African night crawlers. The presence and abundance of 
Eudrilus euginiae might be attributed to the fact that it is extremely prolific 
(Dominguez et al., 2001), has ability to move quickly, capable of surviving in various 
substrates, under polluted conditions (Mainoo et al., 2008) and it is capable of rapidly 
converting wide range of organic substrates such as sewage sludge (Graff, 1982), 
animal wastes (Dominguez et al., 2001), cassava peel (Mba, 1996) and so on. All 
these were present in some of the streams and dumpsites. High-reproduction rates are 
being exhibited by Eudrilus eugeniae (Bano and Kale, 1988; Edwards, 1988) and is 
capable of quickly decomposing large quantities of organic wastes and incorporating 
them into the topsoil (Neuhauser et al., 1979; Neuhauser et al., 1988; Edwards 1988). 
Fabunmi et al. (2016) also collected Eudrilus euginiae earthworms from three 
dumpsites in Port Harcourt, Nigeria. 
Dichogaster modigliani ia also an epigeic earthworm. It was not present in the soil 
from the Idi Ope dumpsite. One of the factors that aided its absence might be the 
cassava processing industry very close to this site. This observation was contrary to 
Jouquet et al. (2006), who found Dichogaster modigliani in a small area of cassava 
plantation. Apart from Dichogaster modigliani that was present in their study site, 
some species of earthworms were absent, which suggested that cassava cropping 
affected earthworm density (Jouquet et al., 2006). Ogunlaja and Morenikeji (2013) 
observed Dichogaster modigliani in an oil pipeline vandalized area in Lagos state, 
Nigeria. 
Hyperiodrilis africanus has been identified as one of the broadly distributed species of 
earthworms  (Barois et al., 1993) existing through humid tropical (Lavelle et al., 
 
 
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1999) Central and West Africa in disturbed and undisturbed fields (Madge, 1969; 
Tondoh, 1998), hence its presence in the soil samples from the streams and dumpsites 
except from the soil from the Odinjo stream and Moniya dumpsite. It is an exotic 
worm that is known to be active in the burial and the decomposition of litter in 
various agro-ecosystems (Hauser, 1993; Hauser et al., 1998; Tian 1995). Dedeke et. 
al. (2010) also observed Hyperiodrilis africanus in friable soils from Olabisi 
Onabanjo University, Ago Iwoye, Nigeria. Hyperiodrilus africanus were also found 
in soil receiving wood wastes from Isale Ake sawmill in Abeokuta, Southwestern, 
Nigeria (Bamidele et al., 2016).  
In situ observation of earthworms’ biomass and population dynamics has been a 
means of determining long-term effects on environment (Kooch and Jalivand, 2008). 
They are regarded as bioindicators of soil quality (Pérès et al., 2011). Due to their 
various activities like burrowing and casting that affect the activities of other 
organisms, the presence of earthworms modifies the soil quality (Kalu et al., 2015). 
Their activity is influenced by soil parameters besides feed (Edwards and Lofty, 
1972). Physical and chemical properties of soil are influenced also by earthworms 
(Jayakumar and Natarajan, 2012). In addition, soil texture, pH and organic matter 
content have major influence on earthworm abundance and diversity (Edwards and 
Bohlen, 1996).  Areas with higher soil organic carbon content sometimes have more 
earthworms (that is, abundance) (Hendrix, et al., 1992; Poier and Richter, 1992; 
Nuutinen, et al., 2001). However, not in all studies (Whalen, 2004; Rossi et al., 2006). 
This could also be seen from the result of the organic matter that despite the low, 
medium and high levels of organic matter in the soils from the streams and dumpsites, 
the earthworm abundance is low. The weak inverse correlations between total organic 
carbon and matter with earthworms’ density of the dumpsites (Appendix 68) may be 
due to the fact that the presence of earthworms depends on factors more important 
than organic carbon, and when present, organic carbon is consumed by earthworms 
(Mainoo et al., 2008). Kale (1998) also reported that the abundance and diversity of 
earthworm species is affected by carbon and nitrogen content of the soil.  
Inverse correlation of total organic carbon and earthworm abundance were also 
observed by Mainoo et al.  (2008) in their sampling of earthworms from some site in 
Accra, Ghana and also Maclean and Parkinson (1997) in their observation of epigeic 
earthworms in a pine forest. This might probably explain the weak inverse 
 
 
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correlations between total organic carbon and matter with earthworms’ density of the 
dumpsites (Appendix 68). However, Kale et al. (2015), observed positive correlation 
of organic matter with earthworm population density in their sampling of Panchase 
area, Nepal. Hendrix et al. (1992) also observed high significant correlation between 
earthworm populations and soil organic carbon content in their sampling of 
earthworms in Georgia Piedmont, USA. 
The high electrical conductivity of the streams and dumpsites implicated that there are 
more soluble salts in the soil (Arias et al. 2005; Karaca, 2004 and Singer and Munns, 
1999). This has implication on survival of earthworms because they cannot tolerate 
high salinity (El-Duweini and Ghabbour, 1965) because high salt concentrations 
cause dessication and eventually death (Schaefer, 2005). This probably explains the 
low abundance of earthworms and also the inverse correlation between the streams’ 
earthworm density and biomass and the electrical conductivity (Appendix 67). 
There is wide recognition of the importance of earthworms for heavy metal 
biomagnifications in terrestrial ecosystems (Karanjal et al., 2010). This could be seen 
from the inverse correlation of streams’ earthworm density and biomass with lead, 
iron, cadmium and positive correlation with zinc (Appendix 67). Owa (1992) and 
Aladesida (2010) also observed positive correlation of earthworm abundance with soil 
iron and calcium. When lead is high, earthworms will not thrive because lead is 
poisonous to their immune system. This might be the reason for the low earthworms’ 
population in soil from the streams and dumpsites, since their lead contents were high. 
The low abundance of earthworms in the dry season could be attributed to changes in 
soil temperature and moisture (Whalen et al., 1998). This was also seen from the 
results, even though the temperature and moisture contents were not analysed.  
 
 
 
 
 
5.2 Physico–chemical characteristics of stream water samples 
The chemical character of any water determines its quality utilization (Elueze et al., 
2004). The quality is a function of the physical, chemical and biological parameters to 
which it could have been subjected to and a particular use it is intended for (Tijani, 
1994). 
 
 
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pH measures the degree of acidity or alkalinity of water and it determines some 
reactions (APHA, 1998). It is important in water quality assessment as it influences 
many biological and chemical processes within a water body (Chapman, 1996); low 
pH increases the availability of metals and other toxins for intake by aquatic life 
(Nartey et al., 2012). The mean pH of the stream water samples fell within the range 
(6.5 – 8.5) recommended for surface water samples by NESREA (2011). Some of the 
samples were a little lower than 6.5, the Omi Adio downstream had pH of 5.48 in 
September, 2008. The pH values observed were related to the range (5.4 – 6.8) 
observed by Ewa et al. (2011) on their study of Omoku creek that receives industrial 
effluent and domestic wastes in Rivers state, Nigeria. They also fell within the range 
7.6 -7.8 observed by Nartey et al. (2012) on their study on the impact of solid waste 
dumpsites on some surface water systems in Accra, Ghana. 
Dissolved oxygen is a measure of the degree of organic pollution in a water body by 
organic matter, the destruction of organic substances as well as self purification 
capacity of the water body (Omole and Longe, 2008). It is a very important abiotic 
parameter because without it, aquatic organisms cannot survive.  It is highly important 
for aquatic life. When it is very low, it can stress the organisms in the water; the 
organisms may move away, get weak or die. The dissolved oxygen content of water is 
influenced by the source, raw water temperature, treatment and chemical or biological 
processes taking place in the distribution system (WHO, 2006). Atmospheric and 
photosynthetic activities are sources of dissolved oxygen in the aquatic environment 
while respiration, decay by aerobic bacteria and decomposition of decaying sediment 
cause loss of dissolved oxygen (Gupta and Gupta, 2006). 
During the sampling periods, there were some months that zero values of DO were 
observed. This might be as a result of organic pollution due to high organic contents 
from human faeces and domestic wastes because the rate of deoxygenation depends 
on dilution that occurs when wastes mix with the stream, the biochemical oxygen 
demand of the discharge, temperature of the discharge and the streams’ DO (Raheem 
and Morenikeji, 2008). The months when DO were observed, the values were lower 
than 4.0 mg/L limit laid down by NESREA (2011) for effluent discharge and also 6.0 
mg/L limit laid down for fisheries and recreation quality criteria standards, also by 
NESREA (2011). The values from the control site (Awba stream) showed that they 
can support aquatic life. There were also reports on surface water bodies with low DO 
 
 
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level amongst which are Lagos lagoon with human sewages and municipal wastes 
discharge (Lawson, 2011), Lower Ogun river caused by organic–rich abattoir 
effluents (Yakub, 2010). Raheeem and Morenikeji (2008) also observed zero DO 
values at the point at which abattoir effluent enters Alamuyo stream in Ibadan, 
Nigeria. 
The values of BOD and COD observed during the sampling periods were higher than 
the limits of 6.0 mg/L and 30.0 mg/L respectively set by NESREA (2011). The low 
DO concentrations observed at the site may be due to high organic load as shown by 
the result of biochemical oxygen demand (BOD) and chemical oxygen demand 
(COD). This probably explains the inverse relationship between BOD and DO, COD 
and DO (Appendix 69). This implies that as the BOD and COD increase, DO 
decreases. The positive correlation between BOD and COD also justifies the fact that 
there is high organic load in the streams. All the stream samples have organic matter 
that is daily imputed into them. For instance, human and animal faecal matters are 
being imputed daily. The contamination of water with faeces increases the BOD 
because it contains mainly organic matter making oxygen less available to desirable 
organisms (Ekundayo, 1977 and Imevbore, 1983). Sudhi (2014) also observed high 
BOD in rivers polluted by faecal contamination in Kerala, India.  
Conductivity is the ability of a solution to pass electric current. Conductivity values 
are often related to the dissolved solids concentrations (Kashiwabara and Tsude, 
1994; Twort et al., 1995). According to Reddy and Reddy (2011), electrical 
conductivity depends on concentration of ions and nutrients status. The high values of 
total dissolved solids (TDS) and electrical conductivity (EC) indicated that there were 
high concentration of anions and cations indicating the presence of inorganic 
materials. Since electrical conductivity of industrial wastewater, treatment plant, 
effluents and polluted waters is due to the presence of ionic solutes (Ademoroti, 
1996), this probably explains the positive correlations of TDS and EC with total 
alkalinity, chloride, phosphate and sulphate. Electrical conductivity is strongly 
influenced by the concentration of dissolved constituents (Obire et al., 2003); this 
probably explains an almost perfect positive correlation between electrical 
conductivity (EC) and total dissolved solids (TDS) (Appendix 69). 
The range of TDS values obtained in the stream samples were far below the range of 
1235 to 19846 mg/L obtained by Obire et al. (2003) in Elechi creek whose banks is 
 
 
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also marked with waste disposal and frequent defaecation in Port Harcourt. The mean 
TDS values obtained in the surface water samples were a little lower than the mean of 
(732±26 mg/L) and (725±75 mg/L) observed at the upstream and downstream 
respectively of a stream in the vicinity of a battery factory in Ibadan, Nigeria 
(Dawodu and Ipeaiyeda, 2008). There are no limits of EC and TDS set by NESREA 
(2011) but Dawodu and Ipeaiyeda (2008) claimed that there is an international 
acceptable level of 1000 mg/L of dissolved solids. They also claimed that since there 
is no limit for electrical conductivity, the values should not reflect an associated 
dissolved solids level. The upstream and downstream of Gege, upstream and 
downstream of Irefin, and upstream and downstream of Odinjo had TDS values that 
were more than 1000 mg/L. This might probably be due to the presence of ionic 
(anions and cations) solutes as seen in their results of sulphate-sulphur, phosphate-
phosphorus, chloride, magnesium and calcium. 
Using the mean values of TDS to classify water according to the classification of 
water based on TDS by Davis and DeWiest (1966) (Appendix 71), Gege stream may 
be useful for irrigation. Also, according to Freeze and Cherry (1979) (Appendix 72), 
all the water types are freshwater except Gege that is a little bit tending towards the 
brackish water type. 
Using their electrical conductivity values to classify their salinity hazards according to 
US salinity laboratory (1954) (Appendix 73), the control stream (Awba stream) and 
Gbagi stream have  low to medium salinity hazards; Gege stream has very high 
salinity hazard; Irefin stream has high to very high salinity hazard; the upstream of 
Omi Adio stream has a low to medium salinity hazard, its downstream has low, 
medium and high salinity hazards; while Odinjo stream has medium, high and very 
high salinity hazards. 
The measure of the capacity of natural water to neutralize acid is alkalinity. It is an 
estimate of the ability of water to resist change in pH upon the addition of acid and it 
is caused mainly due to hydroxide, carbonate and bicarbonate ions (Mahananda et al., 
2010). There is no alkalinity limit stipulated by NESREA (2011). 
Some of the mean total alkalinity values of the stream water samples were higher and 
some were lower than the mean alkalinity values of 369 mg/L and 119 mg/L observed 
by Mahananda et. al. (2006) from two ponds that receive municipal solid wastes and 
different human activities are also carried out at the banks in Bargarh District, Orissa, 
 
 
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India. The range of values obtained were also higher than the range of 4.1 to 18.5 
mg/L by Nkwocha et al. (2011) from points of Otamiri river which is close to 
municipal solid waste dumpsite. The higher alkalinity values obtained in the streams 
may be due to higher concentrations of nutrients, ions and phosphate (which have acid 
buffering properties). 
 
5.2.1 Anion qualities of stream water  
The limit of chloride set by NESREA (2011) for effluent discharge is 300 mg/L. 
Using the mean chloride contents of all the streams, they were not up to the limit. 
However, at some particular periods of sampling, Gege, Irefin and Odinjo upstreams 
and downstreams were higher than the stipulated limit. The high chloride contents 
signified high organic pollutants present in the water bodies at the time of sampling. 
The origin of the pollutants may be due to origin like human and animal faeces, and 
also sewage inflow into the water bodies. 
The range of chloride values observed were far higher than the range of 12.1 to 184 
mg/L observed by Nkwocha et al. (2011). Their mean values were also higher than 
the mean of 11.78 mg/L and 7.59 mg/L observed at the upstream of Rivers Ona and 
Alaro respectively and 9.52 and 12.01 mg/L observed at the downstream of the rivers 
in Oluyole Industrial Estate, Ibadan (Osibanjo et al., 2011). Chloride sources could be 
from soluble salts of NaCl and KCl from blood discharged into abattoir effluent 
(Atuanya et al., 2012) especially in Gege and Gbagi streams that receive blood from 
abattoir. 
Phosphorus is a nutrient that occurs in many forms that are bioavailable and 
phosphate is one of such forms of existence (Nartey et al., 2012). Phosphorus occurs 
in natural waters and wastewaters almost solely as phosphates (APHA, 1998). It is 
often transported to water bodies via soil erosion because many forms of phosphorus 
tend to be adsorbed to soil particles. It also occurs in natural waters in low quantity as 
many aquatic plants absorb and store phosphorus many times their actual immediate 
needs (Mahanada et al., 2010).  
The very high values of phosphate may be due to releases of diverse composition of 
wastes into the stream. It may also be due to solar radiation that might have 
encouraged the biological degradation of the organic matter (Mahanada et al., 2010). 
High levels of total phosphorus and other nutrients have been reported to encourage 
 
 
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eutrophication which could further deplete the dissolved oxygen levels of the rivers 
(Fakayode, 2005; Minareci et al., 2009). This could also be deduced from the 
dissolved oxygen values obtained and the inverse correlation between phosphate and 
DO (Appendix 69). Phosphate may also encourage the growth of algae in the water. 
Nitrate generally occurs in trace quantities in surface water (APHA, 1998). Mean 
nitrate values obtained were below the limit of 40.0 mg/L set by NESREA (2011) for 
effluent discharge. However, there were some sampling periods where the values of 
nitrate in the upstreams and downstreams of Gege and Odinjo and the downstream of 
Gbagi were higher than the set limit for fisheries and recreation but not up to limit for 
effluent discharge. From the point of nitrate pollution, there is no cause of alarm. 
Sulphate is widely distributed in nature and may be present in natural waters in 
concentrations ranging from a few to several thousand milligrammes per litre (APHA, 
1998). Sulphate values were far higher than 500 mg/L set by NESREA (2011) for 
effluent discharge. The high sulphate values could be as a result of the wastes entering 
the water bodies.       
 
5.2.2 Calcium and magnesium 
Calcium and magnesium occur naturally in water bodies and they are among the most 
highly available alkali metals in the environment (Grochowska and Tandyrak, 2009). 
Their concentrations in ground and surface waters increase as they are washed out 
from bedrock (Gałczyńska et al., 2013). Calcium compounds are present naturally in 
surface water, and their concentrations are determined mainly by the carbonate 
balance (Gałczyńska et al., 2013) while magnesium salts are found naturally and in 
high concentrations in surface and ground water (Potasznik and Szymczyk, 2015). 
Calcium levels in the stream water samples were not up to the limit of 180 mg/L set 
by NESREA (2011). So also magnesium levels were not up to the limit of 40 mg/L 
set by NESREA (2011), except at the upstream of Irefin in March 2009, the 
downstream of Gege in July 2009 and the upstream of Omi Adio in January 2010. 
-3
Potasznik and Szymczyk (2015) observed calcium content of 74.0±20.8 mg dm  in 
the Tolknicka Struga stream, which receives wastewater from a local wastewater 
-3
treatment plant and magnesium content of 12.0±4.1 mg dm  within the same stream. 
Grochowska and Tandyrak (2009) observed calcium content between 47.12 and 64.97 
 
 
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mg/L in the waters of Miodówko Lake surrounded by the year-round houses not 
connected to the collective sewerage system but equipped in septic tanks. The 
magnesium content of the same lake varied in the range of 4.4 to 33.2 mg/L 
(Grochowska and Tandyrak, 2009).   
 
5.2.3a Other metals (Pb, Cu, Fe, Zn) 
NESREA (2011) did not set limit for manganese but there are limits for the other 
metals. The range of values of the other elements were more than the set limits by 
NESREA (2011) for effluent discharge, except nickel values of the upstream of Gege 
and Gbagi. Chromium values were also not up to the limit. 
Considering their mean values, lead mean values were higher than the limit for 
effluent discharge except the upstream and downstream of Irefin, upstream and 
downstream of Gege, upstream of Omi Adio and the upstream of Gbagi. 
Mean values of copper, iron and zinc were more than the two set limits. Nickel mean 
values were not up to effluent limit. Cadmium mean values were not also up to 
effluent limit except Omi Adio and the upstream of Gbagi.  
Metals in trace amount may play important role in the biochemical life processes of 
aquatic organisms. However, their sublethal concentrations become lethal to the 
organisms when there is prolonged exposure duration. 
The results obtained from the metal analysis showed that there was high pollution 
indicating that there was high magnitude of metal input from the wastes and effluents 
entering the water bodies. The high levels of metal in the water bodies call for 
concern because of the organisms inhabiting the streams and the larger water bodies 
that the streams feed and also human beings exposed to such environment.  
The high values of metals in the control stream (Awba stream) could be as a result of 
the diffuse nature of lead, run-off activities in cadmium, zinc or lead containing 
materials (Ololade et al., 2009). The presence of lead in the stream samples may be 
due to its discharge from petroleum products. It could also be from lead-acid batteries, 
plastics and rubber remnants, lead foils such as bottle closures, used motor oils and 
discarded electronic gadgets including television, electronic calculators and stereos 
(WHO, 2004). Lead in the environment is mainly particulate bound with relatively 
low mobility and bioavailability (Nartey et al., 2012). According to WHO (1989) lead 
 
 
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does, in general not bioaccumulate and there is no increase in concentration of the 
metal in food chain. However, female animals show impact of lead toxicity by 
miscarriages and potent mortality (Taupean et al., 2001). Fatoki et al. (2002) observed 
the development of neurological problem in fetuses and children exposed to a lead 
concentration of 0.1 mg/L. 
Zinc is an enzyme co-factor in several enzyme systems including the carbonic 
anhydrase found in the red blood cells (Lawson, 2011). It has been found to have low 
toxicity effect in man. However, the prolonged consumption of large doses can result 
in some health complications such as fatigue, dizziness and neutropenia (Hess and 
Schmid, 2002). 
Iron is important in cellular processes of plants and animals. It is found in natural 
waters but when the levels are elevated, it discolours materials such as clothes, plates, 
etc. 
 
 
 
 
5.2.3b Other metals Ni, Cd, Cr, Mn 
High nickel concentration may be due to its presence in wastes of diverse forms and 
particularly in its soluble form. Even in lower concentration, apart from being 
carcinogenic, it can cause allergic reactions in people (Mckenzie and Smythe, 1998). 
Cadmium occurs naturally in zinc, lead, copper and other ores which can serve as 
sources to ground and surface waters, especially when in contact with soft, acidic 
waters (Ololade et al., 2009). High cadmium values in the streams could be due to the 
closeness of the streams to roadside or washing of cars into the streams, for example, 
the Omi Adio and Odinjo streams. Its high concentrations lead to chronic kidney 
dysfunction, inducing cell injury and death by interfering with calcium regulation in 
biological systems in man, fish and other aquatic organisms (Woodworth and Pascoe, 
1982). Its involvement in endocrine disrupts activities, which could pose serious 
health problem (Lawson, 2011). However, its concentrations in water are only likely 
to be of health concern in environments where pH is less than 4.5 (WHO, 2004). 
 
 
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Inhalation of high dose of manganese leads to death. The symptoms in man include 
problems with central nervous system, euphoria, insomnia, serious headache and 
palsy of feet (Lawson, 2011). It is an element of low toxicity having considerable 
biological significance and one of the more biogeochemical and active transition 
metals in aquatic environment (Evans et al., 1977). It occurs in surface waters that are 
low in oxygen and often does so with iron (Lawson, 2011). This probably explains the 
positive correlation with iron. A probable source of airborne inorganic manganese 
pollutant in urban centres is the combustion of methylcyclopentadienyl manganese 
tricarbonyl (MMT), particularly in high traffic density (Sierra et al., 1998). 
Combustion of MMT in hot car engine leads to the emission of manganese 
phosphates, manganese sulphate and manganese oxides that include manganese 
tetroxide as a minor component (WHO, 2004 and Zayed, 2001). 
According to USEPA (2010), the recommended maximum level for manganese in 
water is 0.05 mg/L. Values from the stream water analysis were higher than this 
recommended level. This could be due to MMT, an antiknocking agent in petroleum 
products which has manganese as an active compound.         
 
5.3 Soil contamination by domestic solid waste 
An important component of the terrestrial ecosystem is soil due to its key functions in 
fertility, decomposition processes, nutrient and energy flows (Karanja et al., 2010). 
 
5.3.1 Particle size distribution 
Soils of the banks of the streams had high percentages of sand and very little amounts 
of clay and silt. The soils of the dumpsites also had high percentages of sand and very 
little amounts of clay and silt. These corroborate the works of Oni (2010) who 
observed high percentages of sand in waste dump area of Aba-Eku landfill in Ibadan; 
Benga-Coker and Bafor (1999) observed high percentages of sand of Teboga waste 
dump in Benin City; Anikwe and Nwobodo observed high percentages of sand (72 – 
76 %) from Abakaliki dumpsite. The authors made a conclusion that soils with sand 
content greater than 70 % were unsuitable for waste disposal because they had high 
permeabilities that would allow the leachates pass through them. From their 
conclusion, it could also be inferred that the soils of the study areas are unsuitable for 
dumping wastes. This is confirmed by the results of the groundwater analysis showing 
 
 
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high concentrations of some of the metals or elements in them. This means that the 
metals are seeping through the soil and finding their ways into groundwater bodies. 
This indicated that the soils of the dumpsites are unsuitable for refuse disposal.       
 
5.3.2 Organic matter 
Soil organic carbon is not a requirement for plant growth, however, the levels of 
organic matter in soils influence a number of soil chemical and physical processes and 
it is an important indicator of the soil as a rooting environment (Okalebo et al., 1993). 
Enwezor et al. (1988) classified organic matter levels in soil: organic matter levels 
less than 2 % were considered low (values below critical limits); 2.1 – 3.0 % as 
medium (values above critical limits); and greater than 3.1 % as high. Based on this 
classification, the soils of the control site for the streams (Awba stream) and Gege 
stream ranged from low to medium levels of organic matter while soils of Irefin, 
Odinjo, Gbagi and Omi Adio streams ranged from low, medium and high levels of 
organic matter. The low organic carbon contents of some of the sites could be 
attributed to the utilisation of organic carbon by micro-organisms as a source of 
nutrients for mineralization (Ogbonna et al., 2009). 
Using this classification on soils from dumpsites; all soils from the dumpsites and 
their control site (Balewa) had high organic matter levels. These could be as a result 
of human and animal faeces. High organic matter has been reported by Oni (2010) on 
the analysis of soils in Aba Eku dumpsite in Ibadan. Obasi et al. (2012) also observed 
high organic matter in waste dumpsite soils along Enugu-Port Harcourt expressway. 
Municipal wastes contain a lot of decomposable material that add to the soil organic 
matter (Ideriah et al., 2006). This accounts for the high levels of organic matter in the 
dumpsites’ soil samples since the sites contain major biodegradable wastes like 
domestic litters. However, increased organic matter can lead to increased soil 
productivity (Anikwe and Nwobodo, 2002). 
 
5.3.3 Electrical conductivity 
The soils of the streams had high range of electrical conductivity. This was also 
observed in the soils of the dumpsites, except the control (Balewa). Obasi et al. 
(2012) also observed high electrical conductivity from soils from Enugu-Port 
Harcourt dumpsite and also dumpsite from Zaria. The high electrical conductivity 
 
 
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may be attributed to the presence of metal scraps which is one of the constituents of 
the refuse dumpsite and it implicated that there are more soluble salts in the soil 
(Singer and Munns, 1999; and Karaca, 2004).  
 
5.3.4 Calcium and Magnesium 
Bowen (1979) stated that the World Median value for calcium was 15 000 mg/Kg. 
During the sampling period, the calcium values obtained for the soil samples from the 
banks of the streams and dumpsites were much higher than the 15 000 mg/Kg 
stipulated by Bowen (1979) except for some few months. There were values that were 
even more than twice the World Median level. Plants and animal tissues have calcium 
as one of the inherent constituents, therefore their decay can contribute to the elevated 
concentration of calcium in the environment (Oni, 2010). The vegetative constituents 
of the dumpsites might have also been the reason for the high contents of calcium and 
magnesium (Oketola and Akpotu, 2015). 
Additional sources of calcium may be domestic and industrial wastes (Ademoroti, 
1996). The excessive amount of calcium may indicate some anthropogenic input from 
the wastes dumped in the streams and on the dumpsites.  
Oni (2010) also observed a wide range (18,728.60 – 42,663.85 mg/Kg) of calcium 
with a mean value of 29617 mg/Kg in top soils of waste dump area of Aba Eku 
landfill in Ibadan. Coşkun et al. (2006) also observed high calcium values of 1,750 – 
164,700 mg/Kg with a mean value of 30,700 mg/Kg in Thrace region, Turkey.  
However, Ahmed and Suleiman (2001) observed lower mean calcium value of 1,151 
mg/Kg in soils of Seri-Petalangi landfill in Malaysia. Eddy et al. (2006) also observed 
a range of 100 -142 mg/Kg in their study.   
Eddy et al. (2006) gave the range background levels for magnesium between 1,000 – 
35,000 mg/Kg. The magnesium values for the soils for the banks of streams and 
dumpsites were within this range except in few cases of soil from stream banks. The 
magnesium contents suggest some degree of anthropogenic inputs from the wastes 
dumped on the sites. 
Oni (2010) also observed a high range of 2,303.79 – 6,485.47 mg/Kg with mean value 
of 3,889.33 mg/Kg in top soil samples of waste dump area of Aba Eku landfill in 
Ibadan.  A lower mean value of 53.61 mg/Kg was obtained by Ahmed and Suleiman 
 
 
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(2001) in the soil samples from Seri-Petaling in Malaysia and Eddy et al. (2006) 
obtained lower levels of magnesium (150.5 – 415.5 mg/Kg) which were lower than 
the values obtained in this study. 
The natural limit for potassium as given by Eddy et al. (2006) ranged between 200 
and 2,400 mg/Kg while Bowen (1979) gave a world median value of 14,000 mg/Kg. 
The potassium levels in the soil from the banks of the stream and the dumpsites were 
within this natural limit and the world median value except the Awba stream that had 
a value of 130 mg/Kg in January, May and July 2009 and the same value recorded at 
the Omi Adio stream in November 2009. 
However, the concentration of potassium (8,334.79 – 14,897.29) in top soil levels of 
Aba Eku landfill in Ibadan was quite higher than the ones observed in this study. 
Eddy et al. (2006) also observed a higher range of 15,169 – 22,680 mg/Kg. 
 
5.3.5 Metals 
NESREA (2011) gave a limit of 164 mg/Kg of lead in soil. The results obtained 
showed that the values of lead in the soil samples from stream banks and dumpsites 
were fluctuating around this figure. This suggests a high level of lead contamination 
depending on the composition of the wastes that come in and some other factors such 
as anthropogenic inputs, lead from leaded gasoline and a host of other factors.  
Navas and Machin (2002) stated that a lead range between 10 and 67 mg/Kg is 
frequent in soils of the world. The world median value was 35 mg/Kg as stated by 
Bowen (1979). However, Olade (1987) stated that the background trace element 
content of lead often varies depending on the underlying bedrock type but ranged 
from 16 – 24 mg/Kg and 35 – 150 mg/Kg in tropical soils of Nigeria with mean 
values of 42 and 78 mg/Kg respectively depending on the type of bedrock.  The lead 
values in the soil from the dumpsites fell within the range given by Olade (1987), so 
also some of the soil samples from streams’ banks, except some of them. 
Tijani et al. (2006) gave a range of lead in the soils from Ibadan to be from 20.8 to 
65.3 mg/Kg depending on the bedrock type. Anikwe and Nwobodo (2002) observed 
lead values of 63.4 to 72.1 mg/Kg of municipal waste dump area of Abakaliki as 
compared with 17.3 – 29.3 mg/Kg in the control (non-dump) site. Shomar et al. 
 
 
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(2005) obtained high concentrations of lead that ranged from 146 to 210 mg/Kg in 
agricultural top soils of Gaza strip located near a solid waste dumpsite. 
Eddy et al. (2006) gave the permissible range of manganese levels in soils with a 
range from 200 - 9,000 mg/Kg. Bowen (1979) gave a range of 1000 mg/Kg. However, 
Tijani et al. (2006) gave the range of 77.5 to 387.5 mg/Kg in soils of Ibadan 
depending on the type of the bedrock. Manganese levels in the samples from the 
streams’ banks and the dumpsites had their ranges within the limits given by the three 
authors. 
Comparing the values with other studies indicated that the manganese levels were 
below the range of 2,313.50 to 3,175 mg/Kg observed in dumpsite soil by Eddy et al. 
(2006). The possibility of naturally enriched manganese levels is supported by their 
study, even though there are some evidences of manganese input from the wastes 
dumped. However, Shomar et al. (2005) observed a lower range of 26 to 239 mg/Kg. 
Olade (1987) gave the range of 10 to 270 mg/Kg as background level of zinc in soils 
and the mean values of 74 to 118 mg/Kg depending on the type of bedrock while 
Tijani et al. (2006) gave values of 17.2 to 116.9 mg/Kg as the background values for 
zinc in Ibadan soils. The mean values of zinc obtained from the soil samples from the 
stream banks and dumpsites had higher values than the background values suggested 
by the authors except the control sites that had their mean values within the suggested 
background values. However, the mean values obtained from some of the sites were 
within the 421 mg/Kg limit stipulated by NESREA (2011) except some samples that 
were higher. 
Plants and humans require iron which is an abundant nutrient element, and its toxicity 
is not common (Anikwe and Nwobodo, 2002). Bowen (1979) gave a world median 
value of 40, 000 mg/Kg while Eddy et al. (2006) gave the range of concentration in 
natural background as varying widely between 3,000 to 500,000 mg/Kg. All the iron 
values observed in the soil samples from the study sites fell within the range of 
natural background given by Eddy et al. (2006) and also their mean values fell within 
the world median value given by Bowen (1979) except the mean value observed at the 
Oremeji dumpsite. The high iron concentrations observed in the samples might be 
attributed to the natural concentration of iron in the environment and not only the 
disposed wastes since Ademoroti (1996) reported that natural soils contain significant 
concentrations of iron. 
 
 
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The reason for the high chromium content in the soils from the dumpsites might be 
attributed to wastes from household chemicals and cleaners, diesel engines utilizing 
anti-corrosive agents, rubber, candles, matches and so on (Olayiwola and Onwordi, 
2015). However, Ihedioha (2016) observed low concentrations of chromium during 
rainy and dry seasons (3.6 mg/kg and 4.05 mg/kg respectively) in soil samples 
collected from a municipal dumpsite in Uyo, Nigeria. 
   
 
5.4 Groundwater contamination by domestic solid wastes 
Now-a-days, quality of groundwater is more important than quantity (Hem, 1985). 
Groundwater is protected by the filtering action of soil, but it can still be polluted by 
leaking municipal solid waste or landfills. When there is no access to portable water, a 
lot of water-borne diseases can be transmitted. According to the World Health 
Organization (2015), globally, at least 1.8 billion people use a drinking-water source 
contaminated with faeces and diseases such diarrhoea, cholera, dysentery, typhoid and 
polio can be transmitted through contaminated water.  
Contaminated drinking-water is estimated to cause 502 000 diarrhoeal deaths each 
year (WHO, 2015). In 2014, forty-two (42) countries from all continents reported 190 
549 cases of cholera to World Health Organization (WHO), 55% of the cases were 
reported from Africa (WHO, 2015). The World Health Organization reported that 
there were 5,853 deaths due to cholera in Africa in 1997. There was a reduction to 1, 
882 deaths recorded in Africa in 2014 (Wong, 2015).  This reduction could be 
confirmed from WHO (2015), that 91% of the world’s population had access to an 
improved drinking-water source, compared with 76% in 1990.   
The pH of groundwater samples had various ranges which fell within or outside the 
NESREA (2011) limits for substances and characteristics affecting groundwater for 
domestic use. The wells at the control site (Balewa) and after the Ojokondo dumpsite 
fell within the NESREA (2011) permissible level of 6.5 – 9.2. Others at a particular 
time had pH values that were a little less than 6.5 which showed that they were acidic, 
and at those times, they were not suitable for drinking. Throughout the study period, 
the well close to the Moniya dumpsite showed a range (5.19 – 6.76) that was outside 
the NESREA limit. This indicated acidic level of the water which does not make it fit 
for human consumption. The Duncan’s multiple range tests even showed that it was 
 
 
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the only well that its pH values did not show any significant relationships with any of 
the wells. The acidic nature may be due to the fact that runoff might bring 
contaminants from the dumpsite since it is located downslope the dumpsite and it 
might also be as a result of the water treatment practiced by the owner of the well; the 
chemicals for treatment might not be applied in the correct proportion.  
Organic pollution load of the samples were very high. This statement could be 
confirmed from the result of biochemical oxygen demand (BOD) and chemical 
oxygen demand (COD), and also from the correlation of BOD and COD (Appendix 
70). NESREA (2011) did not set any limit for BOD. But according to Federal 
Environmental Protection Agency (FEPA, 1991) standards for drinking water quality, 
BOD should be 0 mg/L. Throughout the sampling period, there was no particular time 
that BOD was not detected in the samples. The range 18.16 to 140.62 mg/L obtained 
from the samples were higher than the range of -13.0 to 27 mg/L observed in 
groundwater samples from three locations in Ibadan by Oni (2000). It was also higher 
than the range 0 to 52.19 mg/L observed by Adewoyin et al. (2013) from groundwater 
samples located around mechanic workshops in Ibadan. 
Compared with other works, COD range of 60.46 to 200 mg/L was much higher than 
the range (2.16 to 18.67 mg/L) observed by Oni (2010) on two groundwater wells 
around a landfill in Ibadan. It was also higher than the range of 35.0 to 51.5 mg/L 
observed at a well around a battery factory in Ibadan by Dawodu and Ipeaiyeda 
(2008).          
Total dissolved solids’ (TDS) limit was not stipulated by NESREA (2011) but FEPA 
(1991) stipulated limit of 500 mg/L for drinking water standard. The values obtained 
at the control site (Balewa) were acceptable by FEPA (1991). The other samples at 
one time or the other were fluctuating, but throughout the sampling period, the well 
after the Ojokondo dumpsite showed values that were higher than the FEPA (1991) 
limit. Since TDS is a measure of the total concentration of ionic species in a sample, 
that is the sum of cation and anionic concentration; this might probably explain the 
TDS significant positive correlations observed with electrical conductivity, chloride, 
nitrate-nitrogen, sulphate-sulphur, zinc, nickel, magnesium and calcium (Appendix 
70). The higher values of TDS obtained may be due to leaching of contaminants from 
the dumpsites towards the groundwater source or the presence of higher dissolved 
mineral matter. The periods when TDS values were lower than the FEPA limit might 
 
 
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probably be due to the filtering effect of the soil as the contaminants move towards 
the groundwater. 
The mean TDS was higher than the mean 212.13 mg/L of hand dug wells in dumpsite 
areas of Warri observed by Akudo et al. (2010). The range of TDS was lower than the 
range of 267 to 2345 mg/L obtained by Rajkumar et al. (2010) from wells close to 
municipal solid waste dumpsite in Erode city, India. 
Groundwaters are classified depending upon their hydrochemical properties based on 
their TDS values (Carroll, 1962; Freeze and Cherry, 1979). Using the classification 
according to Freeeze and Cherry (1979) (Appendix 71), the values of the sampled 
groundwater showed that they are freshwater except for a brackish water occasionally. 
The well after the Ojokondo dumpsite might be classified as being brackish water 
type because it was just about three times of the sampling that it had values less than 1 
000 mg/L, even those values were between 846 to 901 mg/L.  
Considering the suitability of the groundwater samples for drinking, it is only the well 
at the control site (Balewa) that is suitable for drinking based on the FEPA limit. The 
well water after the Ojokondo dumpsite was not at any time suitable for drinking 
while the other well water samples from the other sites had times when they were fit 
for drinking and there were some other times when they were not fit for drinking. 
Electrical conductivity is a measure of the capacity of water to convey electric 
current. It also signifies the amount of dissolved salts (Dahiya and Kaur, 1999). 
According to Carpenter et al. (2012), polluted groundwater is electrically conductive. 
There is no electrical conductivity limit stipulated by NESREA (2011), but there is 
limit of 440 µS/cm by WHO (1994). However WHO (1997) indicated a limit of 2000 
µS/cm. Throughout the sampling period, the wells before and after the Ojokondo 
dumpsite had values greater than the 1994 WHO limit. However, the well before the 
Ojokondo dumpsite had values lower than the 1997 WHO limit while the well after 
the Ojokondo dumpsite had times when it was lower than 1997 limit and times when 
it was higher.  The other wells had times when they met up with the 1994 limit and 
times when they were greater than the limit. It was only the well at the control site 
(Balewa) that met up with the1994  limit except a particular sampling month that it 
was a little higher (468 µS/cm). The high electrical conductivity values of the 
groundwater samples could be as a result of the effluent from the different wastes 
 
 
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indicating the presence of high amount of dissolved inorganic substances in ionized 
form.  
Using the electrical conductivity values to classify the groundwater salinity hazard 
according to US salinity laboratory (1954) (Appendix 73), the well at the control site 
(Balewa), had low to medium salinity hazard, the wells before the Ojokondo 
dumpsite, the ones close to the Olodo and Idi Ope dumpsites had medium to high 
salinity hazards, the well close to the Moniya dumpsite had low, medium to high 
salinity hazard, the well at the Oremeji dumpsite had medium salinity hazard, while 
the well after the Ojokondo dumpsite had high to very high salinity hazards. 
The range of electrical conductivity values observed in the groundwater samples was 
higher than the range of 344 to 1191 µS/cm observed by Saidu (2011) on groundwater 
close to refuse dumpsites in Minna, Nigeria. 
Alkalinity is the measure of the capacity of natural water to neutralize acid and it is 
due to the presence of hydroxide, carbonate and bicarbonate compounds of calcium, 
sodium and potassium (Devi and Premkumar, 2012). This probably explains the 
positive correlation of alkalinity with calcium (Appendix 70). Alkalinity values in 
drinking water mainly reflect the bicarbonate ion concentration (Sarapata, 1994). 
There is no limit for total alkalinity by NESREA (2011). 
The range of total alkalinity values observed in the groundwater samples during the 
sampling period was higher than the range of 20 to 358 mg/L observed in drinking 
well water in Ibadan by Onianwa et al. (1999). 
Chloride concentration acts as an indicator of pollution by sewage (Devi and 
Premkumar, 2012). Chloride concentrations of the groundwater samples were not up 
to the highest desirable level of 200 mg/L by NESREA (2011) except the well close 
to the Oremeji dumpsite and the one after the Ojokondo dumpsite. However, these 
two wells did not show values up to the maximum permissible level of 600 mg/L also 
by NESREA (2011).    
Considering only chloride to judge the suitability of the groundwater for domestic 
use, all the water samples were suitable for use. High chloride concentration gives an 
undesirable taste to water (Kola–Olusanya, 2011), it is corrosive to metals particularly 
at low alkalinity (Coode, 1997). People accustomed to higher chloride in water are 
subjected to laxative effects (Dahiya and Kaur, 1999). According to Souza and 
 
 
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Somashekar (2012), high chloride concentration in groundwater can affect the people 
suffering from heart and kidney disorders. 
The mean of chloride values observed in the groundwater samples was lower than the 
mean 229 mg/L observed in groundwater samples situated around a surface water 
dumpsite in Ondo state (Ololade et al., 2009).  
There were high levels of phosphate-phosphorus in the samples. Since phosphorus is 
present in natural waters coupled with sources from waste and household detergent, 
this might be the reason for its high levels and this is also an indicator of organic 
pollution. Phosphate-phosphorus values were far higher than 3.5 mg/L limit by 
NESREA (2011) and much higher than the values observed by some authors who 
worked on groundwater samples close to refuse dumpsites (Kola – Olusanya, 2011- 
range of 0.06 to 2.09 mg/L; Adekunle, et al., 2007 – highest mean of 1.49±-0.84 
mg/L; Souza and Soumashekar, 2012 - range of 0 to 1.89 mg/L). 
According to Golwer and Matthess (1968), the process of decomposition of organic 
material exhaust all available dissolved oxygen in the groundwater and give rise to a 
reduction of the nitrate and to a smaller extent of the sulphate, the oxygen which is 
used for the oxidation. This might be the reason for the lower nitrate values in the 
groundwater samples. The nitrate is reduced to elementary nitrogen escaping into the 
atmosphere or to ammonia. The sulphate is reduced to elementary sulphur and to 
hydrogen sulphide. The reduction in nitrate and sulphate originates into bacterial 
action too.       
Nitrate may attain high levels in some groundwater (APHA, 1998). The presence of 
nitrates in groundwater is an indication of a possible bacteriological pollution, which 
may present some health risks (Mbonu, 1991) and can also cause severe illness in 
infants such as Methemoglobinemia. At very high concentrations, it can cause gastric 
cancer (WHO, 1997). The concentrations of nitrate-nitrogen in the samples were not 
up to the highest desirable level of 45 mg/L set by NESREA (2011), therefore the 
groundwater samples based on nitrate-nitrogen contents, they may not constitute any 
danger to human health. From previous works, nitrate-nitrogen values exceeding 
NESREA standards are not very common but there are some exceptional cases. For 
instance, Akinbile (2012) found 61 mg/L of nitrate-nitrogen in one of the three 
groundwater samples close to a landfill in Akure, Ondo state.  
 
 
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Sulphate-sulphur concentrations were observed at a much higher level than 
phosphate-phosphorus and nitrate-nitrogen. They were far higher than the highest 
desirable level and the maximum permissible level of 200 and 400 mg/L respectively, 
including the well at the control site (Balewa). Levels of sulphate act as purgative in 
humans (Esry and Habicht, 1986; Esry et al., 1991). Sulphate occurs naturally in 
water as a result of leaching from gypsum and other common minerals (Manivaskam, 
2005). The discharge of domestic sewage, refuse dumps and industrial wastes tends to 
increase its concentration.    
 
5.4.1 Calcium and magnesium 
NESREA (2011) indicated 75 and 200 mg/L for highest desirable level and maximum 
permissible level of calcium in groundwater for its suitability for domestic use. The 
wells at the Oremeji dumpsite and after the Ojokondo dumpsite at some periods of 
sampling, showed values higher than the highest desirable level but not up to the 
maximum permissible level. 
NESREA (2011) indicated 30 and 150 mg/L for highest desirable level and maximum 
permissible level of magnesium in groundwater for its suitability for domestic use. It 
was also the wells at the Oremeji dumpsite and after the Ojokondo dumpsite that at 
some periods showed values higher than the highest desirable level but not up to the 
maximum permissible level. Using the calcium and magnesium to consider the 
groundwater samples for use, they are suitable for domestic purpose. 
 
5.4.2 Other metals (Pb, Cu, Fe, Zn, Ni, Cd, Mn and Cr) 
Lead, nickel, cadmium and chromium do not have highest desirable and maximum 
permissible levels by NESREA (2011) but they had target and intervention values 
also by NESREA (2011). During the sampling periods, there were times when all the 
four elements were not detected. However, when they were detected, their values 
were fluctuating. 
Copper, iron, zinc and manganese have highest desirable and maximum permissible 
levels by NESREA (2011). There were also periods of sampling that they were not 
detected and the periods when they were detected, they had their values fluctuating 
around the highest desirable and maximum permissible levels by NESREA (2011). 
 
 
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Copper contents were greater than the highest desirable level of 0.05 mg/L but less 
than the maximum permissible level of 1.5 mg/L. Their mean values were less than 
the highest desirable level except the mean values of the well before the Ojokondo 
dumpsite and the one at the Oremeji dumpsite but the two were not up to the 
maximum permissible level.  
The ranges of the values of iron were greater than both the highest desirable and 
maximum permissible levels of 0.1 and 1.0 mg/L respectively. Their mean values 
were also greater than highest desirable and maximum permissible levels except the 
wells close to the Olodo, Idi Ope dumpsites and the one after the Ojokondo dumpsite. 
The ranges of values of zinc in the samples from the Idi Ope well and the well after 
the Ojokondo dumpsite were greater than the highest desirable level of 5.0 mg/L but 
not up to the maximum permissible level of 15.0 mg/L while those from other 
samples were not up to the two limits. The mean values of all the samples were not up 
to the two limits. 
All the ranges of manganese values were greater than the highest desirable level of 
0.05 mg/L and the maximum permissible level of 0.5 mg/L, except those of the wells 
at the control site (Balewa), Olodo and Idi Ope dumpsites that were less than the 
maximum permissible level. The mean manganese values were greater than the 
highest desirable level but not up to the maximum permissible level, except that of the 
well at the Oremeji dumpsite that was greater than the maximum permissible level. 
The elevated levels of metals in the groundwater samples during some sampling 
periods showed that they were not completely free from metal contamination. This 
means that the samples are not totally suitable for drinking or use.  
Heavy metals such as lead, cadmium, chromium, copper, and so on have been 
reported at excessive levels in groundwater due to landfill operations (Lee et al., 
1986; Ogundiran and Afolabi, 2008; Oni, 2010; Akoteyon, 2012; Sanusi, 2013). The 
migration of metals is likely a product of some parameters including soil sorption 
capacity, reaction rate of these elements with solid phase, water movement rate in the 
soil and their primary concentration (Behbahaninia et al., 2010).        
According to APHA (1998), the average abundance of copper in groundwater is less 
than 0.1 mg/L. Some compounds are toxic by ingestion or inhalation. Copper is 
commonly used in electrical wiring, roofing, various alloys, cooking utensils, piping 
 
 
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and in chemical industry. These might be the reasons for its elevated levels in the 
wells at the upper part of Ojokondo and Oremeji dumpsites. 
Copper has been shown to have a protective effect against cadmium poisoning, and 
people who do not have enough copper in their diet can be more susceptible to 
adverse effects from lead (ATSDR, 2005). Although mammals have efficient 
mechanisms to regulate copper stores such that they are generally protected from 
excess dietary copper levels, however at high enough levels, chronic overexposure to 
copper can damage the liver and kidneys (EFS, 2005). 
The average abundance of iron in groundwater is 0.1 to 10 mg/L (APHA, 1998). Most 
groundwater supplies contain some iron because iron is common in many aquifers and 
is found in trace amounts in practically all sediments and rock formations 
(Omofomwan and Eseigbe, 2009). The high levels of iron in the groundwater samples 
could also be as a result of the material used for covering the wells, since they were 
made of iron. Large quantities of iron result in toxic effect like haemochromoitosis in 
tissues if more iron accumulation takes place (Tambekar et al., 2012). Akinbile 
(2006) and Shyamala et al. (2008) remarked that the formation of blue baby syndrome 
in babies and goiter in adults are the results of consumption of water containing iron 
above the specified quantity.          
The average abundance of cadmium in groundwater is from 1 to 10 µg/L. It occurs in 
sulphide minerals that contain zinc, lead or copper. This probably explains the 
positive correlation between cadmium and zinc, and its inverse relationship with lead 
and copper (Appendix 70). Since cadmium is used in electroplating, batteries, paint 
pigments and alloys with various metals, this probably could be the reason for its 
elevated levels in all the samples due to wash down from paint pigments from 
buildings, the various metal scraps from the auto-mechanic workshops beside the well 
at the upper part of the Ojokondo dumpsite and also the Moniya well. 
Cadmium is extremely toxic and accumulates in kidneys and livers, with prolonged 
intake at low levels sometimes leading to dysfunction of the kidney.  
Manganese resembles iron in its chemical behavior and its occurrence in groundwater 
is less abundant than iron. It is found to be lower than iron. Although in deep wells, it 
may reach concentrations as high as 2 to 3 mg/L (APHA, 1998). When solid wastes 
dissolve, they usually contain abundant manganese (Hughes, 2004). Excessive 
 
 
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concentration of manganese would result in taste and precipitation problems (Longe 
and Balogun, 2010).    
According to APHA (1998), the average abundance of chromium in groundwater is 
generally 100 µg/L. It is also used in alloys, in electroplating and in pigments. It is an 
essential trace element for animals. Its hexavalent compounds have been shown to be 
carcinogenic by inhalation and are corrosive to tissue. Their sources could also be 
from the wastes. Even though, chromium salts are rapidly eliminated from human 
body, their heavy doses could corrode the intestinal tract (WHO, 2004).  
 
5.5 Toxicity tests 
As pollution intensity increases, in most cases, there is a decrease of all biological 
indices of environmental health (algae, invertebrates, fish) (Cuffney et al., 2000; Hill 
et al., 2000). In heavily contaminated soil and water, there is a decrease in the 
population, growth and function of biota present (Kaonga and Monjerezi, 2012). This 
could be inferred from the results of the toxicity tests results except for the pollution 
tolerant species. 
 
5.5.1 Eudrilus euginiae earthworms 
The earthworm mortality recorded during the toxicity tests indicated the pollution 
level of the soil samples. Although Eudrilus euginiae species used as test organisms 
can survive in various subtrates under polluted conditions (Mainoo et al., 2008), but 
they are sensitive to disturbances (Dominguez et al., 2001). This might probably be 
the reason for the high mortality recorded during the test. This was contradictory to 
the 100 % survival recorded by Jeyanthi et al. (2016) when the Eudrilus euginiae 
species were exposed to different concentrations of carbaryl and lead at different 
exposure periods. Alemneh (2015) observed 100 %, 87.5%, 50 %, 37.5 % and 25 % 
survival of Eudrilus euginiae when exposed to 0.3, 0.6, 1.2, 2.4 and 5 mg/ml of 
chloroxylenol (dettol) respectively during a 7-day exposure period. He observed 87.5 
% and 75 % survival when exposed to 0.6 and 1.3 mg/ml of sodium hypochlorite 
(parazone) respectively after seven days. He observed 87.5 %, 87.5 %, 75 % and 37.5 
% survival of the earthworms when exposed to 0.7, 1.3, 2.4 and 4 mg/ml of lactic acid 
(Mr Muscle) respectively.  
 
 
 
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5.5.2 Mayflies (Cloeon perkinsi’s) larvae 
There have been significant effects of mayflies’ diversity throughout the world due to 
impact of human activities (Landa and Soldan, 1995). 
The genus Cloeon (Leach, 1815) Ephemeroptera which is one of the most common 
and most diversified genera of mayflies colonizes all kinds of still and standing 
waters, present in riparian vegetation of streams, in ponds, lakes and artificial habitats 
(Salles et al., 2014). Cloeon perkinsi is the most abundant of African Cloeon with 
nymphs occurring in many types of still or slowly moving water from temporary 
ponds to the margin of large lakes (Gillies, 1980). They are valuable indicators of 
water qualities, hence their use for the toxicity assay.  
The contaminated stream samples were highly toxic to Cloeon perkinsi’s (mayflies’) 
larvae. This is attributed to the fact that the presence of mayflies in water indicates 
clean water sources because they prefer cleaner waters (Science, Olympiad, 2013) and 
they are sensitive to chemical pollutants, decreased dissolved oxygen levels, and 
increases in suspended solids (erosion) (Sigurdson, 2010). They are sensitive to 
acidification, heavy metal contamination and low pH levels (Capinera, 2008). The 
reason for the high mortalities recorded during the test could probably be due to the 
fact that all the metals analysed did not meet up with the regulatory standards as 
stipulated by NESREA (2011).  
Sublethal effect of pollution result in altered enzyme function, poor growth, 
behavioural change or lack of reproductive success (Capinera, 2008). Since they are 
important in the food chain, there is pollution effect on other organisms such as 
overgrowth of algae due to death of herbivorous nymphs, over-abundance of prey 
species due to scarcity of predacious nymphs (Capinera, 2008). However, mayflies 
help in removing pollutants from aqueous systems by processing a lot of great 
quantity of organic matter and transferring a lot of nitrates and phosphates to 
terrestrial environments when they emerge as adults from the water (Dominguez, 
2006). 
Ogbogu (2003) also carried out a 48 hour static bioassay exposing Cloeon perkinsi’s 
larvae to 5, 10, 15 and 20 mg/L each of stock solutions of sodium chloride, sodium 
sulphate, sodium hydrogen phosphate and potassium nitrate.  He observed that at all 
concentrations of phosphate solution, survival was below 10 %, survival in nitrate 
 
 
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solution was high (70 %) at 5 mg/L but decreased as concentration increased, 
reaching mimimum (7 %) at 20 mg/L. In chloride and sulphate solutions, survival 
varied between 40 % and 70 %. He commented that very low levels of phosphate 
concentration in water can impair production of low Cloeon perkinsi in reservoirs, 
higher concentrations of nitrates around 20 mg/L can also impair Cloeon perkinsi 
production. This could be observed in the very high phosphate result of the test 
solutions. Beketov (2004) observed LC 50 value of 19.05 % for Cloeon bifidum larvae 
when exposed to a mixture of 59.0 % ammonia, 1.5% nitrite and 39.5 % nitrate. 
However, Cloeon dipterum larvae could support water of low quality (α-β 
mesosaprobic) and even temporary anoxia (Nagell, 1977). There was a case of Cloeon 
dipterum larvae which were exposed to laboratory anoxic condition. About 50 % of 
o
the larvae survived 130 days of anoxia at 0 C; the most resistant surviving 155 days. 
Undissociated H2S (1.4 mg/L) in the anoxic water did not reduce the survival. 
Severely starved larvae survived anoxia for only 16 days (LT50) (Nagell, 1977). This 
was due to the fact that the larvae are facultative anaerobes and will use oxygen if it is 
available in winter (Nagell, 1977). 
 
5.5.3 Tadpoles (Rana temporaria) 
Amphibians are bioindicators of environmental stress (Hall and Mulhern, 1984; 
Freda, 1991; Dunson et al., 1992), especially due to decline of some population 
(Barinaga, 1990). Decline of some population has been linked to environmental 
contamination and potential adverse effects of chemical exposure (Blaustein et al., 
1994). 
Tadpoles growth and survival can be affected by alterations in environmental factors 
such as limitation of resources, predation, crowding and dessication of habitat (Shi, 
2000). Exposure of tadpoles to contaminants can lead to frogs with many types of 
malformation. For example, frogs without eyes, with extra or missing legs, or deadly 
malformations (U. S. Fish and Wildlife Service, 2000). If the tadpoles exposed to 
stream test solution of Gbagi, Odinjo and Omi Adio were left for more than 96 hours 
and the growth to frogs observed, it is possible that some of these malformations 
would occur. 
Tadpoles of Rana catesbeiana collected in coal ash deposition basin (contaminated 
with arsenic, cadmium, chromium, copper, selenic and other elements) and a 
 
 
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downstream drainage swamp had a reduced number of labial teeth and deformations 
of labial papillae when compared with tadpoles from reference areas (Rowe et al., 
2014). Tadpoles with deformities were less able to graze periphyton than the normal 
tadpoles when tested in the laboratoty. When given periphyton as sole food, they had 
lower negative growth rates than the ones with normal teeth (Rowe et al., 2014). 
Since the toxicity assay was just for 96 hours, these deformities could not be observed 
in the test experiments. 
Juveniles of anurans accumulated greater concentrations of polychlorinated biphenyls 
(PCBs) compared to adults collected from the same contaminated stream locations 
flowing from Paducah gaseous diffusion plank in Paducah, Kentucky (De Garady and 
Halbrook, 2005).  
High electrical conductivity impacted the growth, development and survival of 
various anuran tadpoles of brown tree frog, Litoria ewingii exposed to high saline 
condition (Chinathamby et al., 2006). Electrical conductivity above 3 000 µS/cm had 
negative impacts on anurans species presence (Smith et al., 2007). However, the 
electrical conductivity values of the test solutions were not up to 3 000 µS/cm, death 
of the tadpoles observed might be due to the high values of electrical conductivity. 
Chronic exposure of calcium phosphate significantly reduced the survival of Litoria 
aurea tadpoles of a fertilizer-applied agricultural land in southeastern Australia 
(Hamer et al., 2004). The death of tadpoles exposed to the contaminated-stream water 
of Irefin and Gege might be due to the high phosphate contents of the samples. 
Endosulfan, which is an organochlorine pesticide affected Rana temporaria tadpoles 
(Denoel et al., 2013). The tadpoles travelled shorter distances, swam less often at a 
lower speed and occupied less peripheral position than control tadpoles (Denoel et al., 
2015). Survival of the tadpoles was reduced after long-term exposure, which was 
associated with short-term behavioural dysfunctions. Therefore, endosulfan strongly 
affects behavioural repertory of amphibian tadpoles (Denoel et al., 2015).   
Furthermore, Rana temporaria tadpoles were developed in simulated experiments of 
ponds littered with metal-containing refuse ponds (Severtsova and Gutierrez, 2013). 
Retarded growth was observed in the tadpoles exposed to the water polluted with lead 
and the tadpoles were significantly smaller than the control group. However, those 
 
 
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developing in iron polluted water had an increased body size when compared with the 
control group.  
 
5.5.4 Fishes (Frys and fingerlings of Clarias gariepinus) 
Fishes are widely used to check the health of an aquatic body, hence the use of 
Clarias gariepinus frys and fingerlings. The link of fish to man in the food chain 
makes it to be a major test organism in ecotoxicological studies (Oshode et al., 2008). 
They may provide advanced warning of the potential danger of new chemicals and the 
possibility of environmental pollution, if they are used for the assessment of water-
borne and sediment-deposited toxins (Powers, 1989). 
Clarias gariepinus is very hardy, however, the frys and fingerlings cannot tolerate 
pollution stress since the organs are not well developed. This led to the mortalities of 
the frys and fingerlings observed because of the high contamination level of the 
streams.  
Clarias gariepinus is of commercial importance in aquaculture due to its positive 
attributes like resistance to diseases, high fecundity, and ease of larval production 
(Hogendoorn, 1980; Haylor, 1991; Kestemont et al., 2007). However, there is low 
survival during the larval and fingerling stages (De Graaf and Jannsen, 1996) which is 
attributed to infectious diseases caused by parasites (Bricknell and Dalmo, 2005). 
Haematology is used as an index of fish health status in a number of fish species to 
detect physiological changes following different stress conditions like exposure to 
pollutants, diseases, metals, hypoxia, and so on (Blaxhall, 1972; Duthie and Tort, 
1985). 
Oshode et al. (2008) after 96 hour exposure of fingerlings to 25 %, 35 % and 45 % 
concentrations of raw leachate collected from Aba Eku landfill, Ibadan, they observed 
20 %, 40 % and 100 % mortalities respectively. They also observed abnormalities in 
the livers, gills and kidneys and physiological changes in the haematological 
parameters of the exposed fishes. Aderemi et al. (2012) also observed 20%, 40%, 
60% and 80% mortality of Clarias gariepinus fingerlings when exposed to 1%, 2%, 
3% and 5% concentrations of municipal landfill leachate respectively for 96 hours. 
However, no mortalities of Clarias gariepinus fingerlings were observed when 
exposed to 20 %, 40 %, 60 %, 80 % and 100 % concentrations of domestic effluent 
 
 
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discharge from a female hostel in Niger Delta University, Nigeria (Aghoghovwia et 
al., 2015). 
Endosulfan was highly toxic to juveniles of Clarias gariepinus. The 96 hour LC50 
value obtained was 0.052 ppm, there was decrease in haematological values (PCV, 
Hb and RBC), which might be due to haemolysis of red blood cells leading to 
significant decrease in haematocrit which resulted in fish anaemia (Yekeen and 
Fawole, 2011). 
Furthermore, fingerlings of Clarias gariepinus were exposed to lethal concentrations 
of herbicide 2,4-Dicholorophenoxyacetic acid (Shallangwa, 2011). The exposed 
Clarias gariepinus exhibited agitated swimming, loss of equilibrum, air gulping, 
period of quiescence and the fish turned on its flank and swarm in circles and finally 
died. The 96 hour LC50 value obtained was 86 mg/L. 
In addition, adults of Clarias gariepinus were exposed to various concentrations of 
cassava effluent, death occurred at 15 ml concentration of cassava wastewater. 
Various heamatological responses were observed, which include anaemia, higher total 
white blood cell than control, and histopathological lesions which include severe 
necrosis, hypertrophy and vacuolation of hepatocytes (Adeyemo, 2005). According to 
NESREA (2011), the limit of oxygen for effluent discharged into a stream should not 
be less than 4 mg/L for organisms to be able to survive in it. Irefin and Gbagi test 
solutions had zero (0 mg/L) DO, Odinjo had 1.07 mg/L, this could be attributed to 
stress which eventually led to the death of the frys and fingerlings exposed to the test 
solutions.  
In order for fish to survive in an aquatic medium, the physico-chemical qualities of 
the water should meet up with regulatory standard. Low quality water results in weak, 
sick and eventually death of fishes.   
 
5.6 Conclusion and recommendation 
The low diversity and abundance of earthworms present in the soil from the streams 
and dumpsites indicated that the sites were highly contaminated and polluted. This 
resulted from the low qualities of the soil, which could not support the existence of 
various species of earthworms.  
 
 
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There should be improvement of the soil qualities so that soil health would be better 
improved; all soil-dwelling fauna (not only earthworms) could be preserved and they 
will not go into extinction.  
The results of the physico-chemical qualities of the streams showed that streams were 
highly polluted because the qualities could not meet up with the standard as stipulated 
by NESREA (2011). The low physico-chemical qualities of the streams had a 
negative impact on the survival of the different test organisms used for the bioassay. 
Therefore, efforts should be made in preserving our aquatic health and also for the 
survival of aquatic organisms. 
The physico-chemical qualities of the groundwater samples close to the streams and 
dumpsites indicated that the groundwater samples were contaminated and since all 
their qualities did not meet up with the standards for drinking water, therefore, they 
were not fit for drinking. 
The study showed that apart from wastes that were being dumped on the land, a lot of 
activities going on around the sites had negative effects on the existence of 
earthworms, soil, stream, groundwater and existence of aquatic organisms. Some of 
the activities include washing of abattoir wastes into streams without prior treatment 
of the effluent such as occurring in Gege and Gbagi. Auto-mechanic workshops 
around Ojokondo, Oremeji and Moniya, washing of cars and motor cycles as 
occurring in Odinjo and Omi Adio. Cassava processing as observed in Idi Ope, and 
food vendor around the Odinjo upstream, Gbagi and Omi Adio downstream.  
In order to ensure sustainable management of conservation of soil and aquatic 
biodiversity as well as socio-economic importance of aquatic and soil resources of 
Ibadan, the following regulatory measures are therefore recommended: 
There is need for waste management by waste reduction, reuse and recycling when 
and where appropriate. Each household should have refuse bins in front of the house 
and the Government should intensify more efforts on the collection of the waste from 
the households and the further movement to landfill sites that have been designated 
for dumping of wastes. There should be public enlightenment on the impacts of 
disposing wastes into water bodies and indiscriminately on land, such as 
susceptibitlity of inhabitants around the wastes sites to various diseases and infections 
such as cholera, typhoid and some other water-borne diseases, apart from negative 
 
 
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impacts on aquatic dwelling organisms. Public health officers should inspect various 
houses especially around the core or low income areas, for provision of toilets for 
defaecation. 
Furthermore, abattoir owners and workers should be enlightened on the impacts of 
washdown of abattoir on public health, the environment and the fragility of the 
ecosystem. Treatment of abattoir effluent should be encouraged. There should be 
proper monitoring of abattoir to enhance compliance with hygienic requirements and 
sanitary regulations to reduce the transmission of zoonotic diseases. Regulatory 
bodies should strengthen the enforcement and punitive aspect of their responsibilities 
so that those who infract on environmental safety standards should be brought to book 
to serve as deterrant either in form of fines or punishment. 
In addition, auto-mechanic engineers and car wash operators should be enlightened on 
the impact of their disposal on land and in water. Environmental friendly techniques 
should be employed and their wastes must be treated before disposal.  
For the cassava processing site, waste water should be treated before being released 
and such water can be used for irrigating crops or safely released to rivers or streams. 
Solid waste such as cassava peels, fibrous residue and starch residue can be disposed 
by land filling and can be dried to produce animal feed. 
The need for further studies on the work include a longer exposure duration of 
earthworms for the bioassay test to check changes or alterations in the survived 
earthworms in their aspects of reproduction, cocoon production, alterations in newly-
developed earthworms; haematological and histopathological variations in exposed 
earthworms. Bioremediation should also be checked.   
Furthermore, there is need for increased and continued combined environmental 
intervention, enlightenment and awareness programmes. These should be organized 
through public health workers for local residents on the environmental devastations 
that result from indiscriminate dumping of untreated wastes into the natural water 
bodies and on land as well as the benefits of adequate waste management measures.  
In addition to the aquatic toxicity assays, tadpoles should be exposed for a longer 
duration to check for the likely alterations in metamorphosised frogs. Then the 
survived tadpoles during the 96 hour test should also be subjected to various 
histopathological and haematological tests. Frogs should be collected from the sites to 
 
 
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check for probable biochemical alterations in their vitellogen production, like the 
exhibition of female characters in the male frogs. 
Public health aspect of the work should be carried out to check the effects of the waste 
disposal sites on human beings inhabiting the areas. This should be done by the use of 
questionnaires to interview inhabitants close to waste disposal sites on the health 
challenge they are constantly faced with. Information should also be gathered from 
hospitals near the waste sites to check for the data on the occurrence of food-, air- or 
water-borne infections like cholera, dysentery, diarrhoea, typhoid, hepatitis A and E, 
zoonotic diseases and some other infections that have been reported.   
Lastly, this study serves as a database to initiate remediation programmes for the 
already affected sites (soil, surface water, groundwater) and check how the natural 
biota can be effectively conserved.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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