The Impact of Using Polluted Benue River and Shinko Waters on Irrigated
Vegetables at Geriyo, Nigeria
ALIYU HALIRU HONG
Doctor of Philosophy
(Environmental Engineering)
2015
Faculty of Engineering
THE IMPACT OF USING POLLUTED BENUE RIVER AND SHINKO
LAKE WATERS ON IRRIGATED VEGETABLES AT GERIYO, NIGERIA
ALIYU HALIRU HONG
A thesis submitted in fulfillment of the requirement for the award of Degree of Doctor of
Philosophy
FACULTY OF ENGINEERING
UNIVERSITI MALAYSIA SARAWAK
i
ABSTRACT
Water pollution and scarcity are identified as the major challenge affecting food production
through irrigation in a sahelian region of Africa. However, the impact of using polluted water for
irrigation on soil and edible crops and the associated risk from heavy metals loaded in polluted
water, soil and crops on consumers remains uncertain. A typical case of this is in Yola, Adamawa
State, Nigeria where high quality irrigation water is scarce. To close this gap, this PhD research
studied the impact of polluted river and lake water characteristics, and heavy metal concentration
levels in water, soils and irrigated vegetables. Health risk index for consumption of heavy metals
in polluted vegetables were estimated on adult and children through the water – soil – plant food
chain transfer pathway from two irrigation sites of Geriyo catchment area using standard
methods. The result of water characteristics and heavy metals indicated significantly high level of
pollutants with most of the parameters above the threshold levels set by FAO/WHO and FEPA
Standards for irrigation water uses. Heavy metal concentration levels in soil across the two sites
indicated significant difference in concentration of heavy metals with Shinko Lake site soil
higher than River Benue site. Heavy metal concentration levels in soils of the two sites have been
impacted due to accumulation of metals in water and soil, with most of the values above the
international critical threshold levels set by EU, USA, Canada and UK. The calculated metal
pollution index (MPI) of the two soils revealed severe contamination of soil, to severe pollution
of soil with heavy metals; with potentials of effecting plant growth and ground water
contamination. The evaluated heavy metal transfer factor from soil into vegetables which is a key
component of metal exposure was observed to be higher due to high percentage of sand fraction
and low soil pH. Vegetables showed evidence of bioaccumulation of heavy metals from both
ii
sites; with their maximum values above permissible level of heavy metals in vegetable set out by
FAO/WHO (2007) standard. The evaluated food chain transfer of heavy metals via the
consumption of contaminated vegetables based on determined daily intake rate of 345g/day and
232g/day for adults above 18 years of age with body weights category of 60, 50, and 40 kg; and
children below 18 years of age, with body weights of 32.5, 22.5 and 12.5kg using health risk
index tool (HRI) revealed that health risks of heavy metals in vegetables are due to Cu and Pb
elements. For adults consumers of vegetables with body weights of 60, 50, and 40 kg; the
estimated health risk index range from 1.112 - 1.114, 1.0850 – 1.3358 and 1.0630 – 1.6697 are
due to ingestion of Pb and Cu in cabbage, amaranthus and tomatoes. For children with body
weights category of 32.5, 22.5 and 12.5kg, estimated health risk index range of 1.1180 – 1. 3830,
1.6218 – 1.9983 and 1.0294 – 3.5969 are due to Pb and Cu in vegetables. The results indicated
that children with body weights under 12.5kg are more prone to heavy metal exposure from
intake of these vegetables, as their estimated health risk index are higher than other body weights
of consumers. The long time toxic effect of food chain transfer and accumulation of Cu and Pb
on human body organs, such as liver, kidneys, spleen and lungs to cause defects is a serious
source of concern. Urgent integrated health risk management and risk education need to be taken
by local authority in the area.
iii
ABSTRAK
Pencemaran air dan kekurangan sumber air telah dikenal pasti sebagai cabaran utama dalam
pengeluaran makanan melalui pengairan di rantau Sahelian Afrika. Walau bagaimanapun, kesan
penggunaan air tercemar melalui pengairan tanah dan tanaman dan juga risiko yang boleh
dikaitkan dengan pemakanan logam berat di dalam air yang tercemar, tanah dan tanaman kepada
pengguna masih tidak menentu. Kes tipikal seperti ini terdapat di Yola, Adamawa State, Nigeria
di mana air pengairan yang berkualiti sangat sukar untuk didapati. Untuk merapatkan jurang ini,
penyelidikan PhD ini mengkaji kesan sungai dan air tasik tercemar melalui ciri-ciri dan tahap
kepekatan logam berat di dalam air, tanah dan sayur-sayuran pengairan dan juga risiko terhadap
kesihatan pemakanan logam berat dalam sayur-sayuran yang tercemar pada orang dewasa dan
kanak-kanak merangkumi air - tanah - tumbuhan laluan pemindahan rantai makanan dari dua
kawasan tadahan tapak pengairan Geriyo menggunakan kaedah piawai. Hasil menunjukkan ciri-
ciri air dan logam berat barada pada tahap yang jelas tinggi dengan bahan pencemar iaitu
kebanyakan parameter melebihi paras ambang yang ditetapkan oleh FAO / WHO dan Piawaian
FEPA untuk air pengairan. Tahap kepekatan logam berat dalam tanah di kedua-dua tapak,
mendapati perbezaan yang ketara dalam kepekatan logam berat dengan tapak kajian Tasik
Shinko memberi bacaan yang lebih tinggi berbanding tapak Sungai Benue. Tahap kepekatan
logam berat dalam tanah kedua-dua tapak telah terjejas disebabkan pengumpulan logam dalam
air dan tanah, dengan sebahagian besar daripada nilai-nilai berada di atas paras kritikal
antarabangsa yang ditetapkan oleh Kesatuan Eropah, Amerika Syarikat, Kanada dan United
Kingdom. Indeks pencemaran logam (MPI) pada kedua-dua tanah mendedahkan pencemaran
tanah yang teruk dengan logam berat, sehingga berpotensi untuk memberi kesan terhadap
pertumbuhan tumbuhan dan pencemaran air bawah tanah. Nilai faktor pemindahan logam berat
iv
dari tanah ke dalam sayur-sayuran yang merupakan komponen utama yang diperhatikan dalam
pendedahan logam menunjukkan bacaan lebih tinggi disebabkan oleh tekstur tanah dan ciri-ciri
pH. Sayuran menunjukkan bacaan bio logam berat dari kedua-dua tapak; dengan nilai-nilai
maksimum di atas paras yang dibenarkan untuk logam berat dalam sayur-sayuran yang
ditetapkan oleh piawai FAO / WHO (2007). Nilai pemindahan logam berat melalui rantai
makanan, penggunaan sayur-sayuran yang tercemar ditentukan berdasarkan kadar pengambilan
harian 345g / hari dan 232g / hari untuk orang dewasa berumur 18 tahun dengan kategori berat
badan 60, 50, dan 40 kg; dan kanak-kanak di bawah 18 tahun, dengan berat badan 32.5, 22.5 dan
12.5kg. Menggunakan alat indeks risiko kesihatan (HRI) telah mendedahkan bahawa logam berat
amat berisiko terhadap kesihatan disebabkan oleh elemen Cu dan Pb dalam pemakanan sayur-
sayuran yang tercemar. Bagi pengguna dewasa dengan berat badan 60, 50, dan 40 kg, anggaran
indeks risiko kesihatan memberi bacaan 1.112 - 1.114, 1.0850 – 1.3358 dan 1.0630 – 1.6697
adalah disebabkan oleh pengambilan Pb dan Cu dalam kubis, Amaranthus dan tomato. Bagi
kanak-kanak dengan kategori berat badan 32.5, 22.5 dan 12.5kg, anggaran indeks risiko
kesihatan memberi bacaan 1.1180 - 1. 3830, 1.6218 - 1. 9983 dan 1.0294 - 3.5969 adalah
disebabkan oleh Pb dan Cu dalam sayur-sayuran. Hasil kajian menunjukkan bahawa kanak-kanak
dengan berat badan bawah 12.5 kg lebih cenderung terhadap pendedahan logam berat dari
pengambilan sayur-sayuran ini, dengan anggaran indeks risiko kesihatan mereka adalah lebih
tinggi daripada berat badan pengguna. Ini disebabkan kesan toksik Cu dan Pb lebih tertumpu
kepada organ-organ tubuh manusia, seperti hati, buah pinggang, limpa dan paru-paru
menyebabkan kecacatan, yang mendesak pengurusan risiko kesihatan dan keperluan pendidikan
terhadap risiko yang perlu diambil oleh pihak berkuasa tempatan di kawasan itu.
v
ACKNOWLEDGMENTS
First of all, praise is to almighty God for giving me the strength, patience and wisdom to
complete this work successfully. I would like to express my sincere and immense gratitude and
appreciation to my supervisor Prof. Ir. Dr. Law Puong Ling for his help, guidance, patience and
wonderful supervision despite his tight schedules did a painstaking supervision of my PhD
research. You have certainly demonstrated a superb quality mentorship. I would also like to
thank and appreciate the guidance and invaluable co-operation and support to my co supervisor
Dr. Onni Suhaiza Selaman for her constructive criticisms and helpful comments were also central
to the success of this work. I am most grateful to you all.
I also greatly appreciate the entire management of Civil Engineering Department, Faculty of
Engineering, and the Centre for Postgraduate Studies CGS University of Malaysia Sarawak for
providing the enabling environment and support throughout my period of study in UNIMAS.
Special thanks and appreciations to my Department, employer and the entire Management of
Madibbo Adama University of Technology, Yola, Adamawa State, Nigeria for granting me a
study fellowship. My special thanks and appreciation also go to the Tertiary Education Training
Fund (TET Fund) for granting to me PhD study grant to complete this study. I am extremely
grateful.
I would also like to express my appreciation and gratitude to my beloved Parents Hajiya Dikko
and the entire members of Late Alhaji Haliru Adamu Badi family. Your prayers, inspiration,
guidance, care and support were a ladder to my adulthood.
To my darling wife Zainab Late Alhaji Yusuf Kama, my children, Abdulmajid, Abdulmalik,
Nana Aisha and Abdulrazak your support is immeasurable. You are indeed an invaluable treasure
vi
to me. I am deeply grateful for your understanding and patience while away in the course of this
study. To those who contributed in one way or the other to the success of this work whose names
are too numerous to mention, your entire effort is duly appreciated.
vii
TABLE OF CONTENTS
CONTENTS Page No.
ABSTRACT i
ABSTRAK iii
ACKNOLEDGEMENTS v
TABLE OF CONTENTS xii
LIST OF FIGURES xviii
LIST OF TABLES xix
LIST OF ABBREVIATIONS xxi
LIST OF PUBLICATIONS xxiv
CHAPTER 1 INTRODUCTION
1.1
Research Background
1
1.2 Problem Statement 4
1.3 Research Objectives 4
1.4 Research Hypothesis 5
1.5 Rationale 6
1.6 Scope of Research 7
1.7 Layout of the Thesis 8
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 9
2.2 Soil and Water Pollution in the Environment 9
2.2.1 Causes of Soil Pollution 10
2.2.2 Causes of Water Pollution 10
2.2.3 Effect of Soil and Water Pollution 12
2.3 Wastewater Definition and Classification 12
2.3.1 Agricultural Wastewater 13
2.3.2 Industrial Wastewater 13
2.3.3 Municipal Wastewater 13
viii
2.4 Heavy Metals 15
2.4.1 Lead (Pb) 16
2.4.2 Cadmium (Cd) 17
2.4.3 Chromium (Cr) 17
2.4.4 Copper (Cu) 18
2.4.5 Iron (Fe) 19
2.4.6 Zinc (Zn) and Manganese (Mn) 19
2.4.7 Nickel (Ni) 20
2.5 Heavy Metals Availability in Soil 20
2.5.1 Factors Affecting Movement of Heavy Metals in Soil 21
2.5.2 Water Scarcity and Irrigation Water Demand 22
2.5.3 Role of Irrigation Water in Crop Contamination 23
2.5.4 Irrigation Water Quality 25
2.5.5 Wastewater Irrigation Application Methods 26
2.5.6 Risk Associated with Irrigation Water and Pathogens 28
2.5.7 Global Assessment of Wastewater Reuse in Irrigation 30
2.5.7.1 Direct use of Treated Wastewater 32
2.5.7.2 Direct use of Untreated Wastewater 33
2.5.7.3 Indirect use of Untreated Wastewater 33
2.6 Vegetables as Vehicle for the Transmission of Pathogen 37
2.6.1 Epidemiological Considerations 37
2.6.2 Sources of Vegetable/Crop Contamination 41
2 .6.3 Mechanism of Microbial Adhesion to Vegetables/Crops 43
2.6.3.1 Salmonella typhi 43
2.6.3.2 Escherichia coli 44
2.6.3.3 Cryptosporidium Oocysts 45
2.6.3.4 Giardia cysts 46
2.7 Bioaccumulation and uptake of Heavy Metals by Vegetables 47
2.7.1 Harzadous effects of heavy metals 49
2.7.2 Risk Assessment of Heavy Metals Pollution in Soil, Water 50
ix
and Vegetables
2.8 Recent Findings of Heavy Metal Contamination in Vegetables in
Different Countries
55
CHAPTER 3 MATERIALS AND METHODS
3.1 Overview 65
3.2 The Study Area 65
3.3 Analytical Program me 69
3.4 Field Work/Measurements 72
3.4.1 Water Sampling 72
3.4.2 Sampling Method and Procedure 72
3.4.3 Irrigation Field Plot Setup 73
3.4.4 Soil Sampling 75
3.4.5 In – situ Measurement 75
3.5 Laboratory Analysis of Samples 77
3.5.1 Sample Preparation 77
3.5.2 Irrigation Water Sample Digestion 77
3.5.3 Soil Sample Digestion 77
3.5.4 Vegetable Sample Digestion 78
3.5.5 Instrument Calibration 79
3.6 Physicochemical Quality Analysis of Water Samples 80
3.6.1 Total Suspended Solid and Total Solids 80
3.6.2 Total Dissolved Solids 80
3.6.3 Turbidity 80
3.6.4 Alkalinity 81
3.6.5 Chloride 81
3.6.6 Biochemical Oxygen Demand (BOD) 81
3.6.7 Chemical Oxygen Demand 82
3.6.8 Total Nitrogen 83
3.6.9 Total Phosphorus, Nitrate and Sulphate 84
3.6.10 Analysis of Heavy Metals in Water Samples using 210VGP 84
x
3.7 Physicochemical Properties Analysis of Soil 86
3.7.1 Soil Particle Size Analysis 86
3.7.2 Soil pH 86
3.7.3 Soil Electrical Conductivity 87
3.7.4 Soil Organic Matter 87
3.7.5 Analysis of Heavy Metals in Soil and Vegetables Samples 88
3.7.6 AAS Analytical Techniques 88
3.7.7 Instrument Calibration 89
3.7.8 Uncertainty in Measured Data 89
3.8 Calculation of Metal Transfer Factor from Soil into Vegetables 90
3.9 Calculation of Metal Pollution Index for River and Lake Site 90
3.10 Computations of Daily Intake of Heavy Metal and Evaluation of
Health Risk Index
91
3.11 Data Analysis and Evaluation 92
CHAPTER 4 RESULTS AND DISCUSSION
4.1 Physicochemical Characteristics of Impacted River Benue and Shinko
Lake Water Quality
96
4.1.1 Total Solids 96
4.1.2 Electrical Conductivity and Total Dissolved Solids 97
4.1.3 Total Suspended Solids 99
4.1.4 Temperature 100
4.1.5 Turbidity 100
4.1.6 pH 102
4.1.7 Alkalinity 105
4.1.8 Chloride 106
4.1.9 Dissolved Oxygen 107
4.1.10 Biochemical Oxygen Demand 109
4.1.11 Chemical Oxygen Demand 112
4.1.12 Nutrients (N, P,K) in River and Lake Water 113
4.1.13 Cat ions (Na, Ca, Mg) in River and Lake Water 115
xi
4.1.14 Anions ( S042-
, NO3-) 116
4.2 Heavy Metal Concentration Levels of River Benue and Shinko Waters 125
4.2.1 Iron (Fe) in River and Lake Water 125
4.2.2 Zinc (Zn) in River and Lake Water 126
4.2.3 Manganese (Mn) in River and Lake Water 126
4.2.4 Copper (Cu) in River and Lake Water 128
4.2.5 Cadmium (Cd) in River and Lake Water 129
4.2.6 Chromium (Cr) in River and Lake Water 130
4.2.7 Lead (Pb) in River and Lake Water 131
4.2.8 Nickel (Ni) in River and Lake Water 131
4.3 Physicochemical Properties of River and Shinko Lake Sites Soil 136
4.3.1 Soil pH 136
4.3.2 Soil Electrical Conductivity 138
4.3.3 Soil Organic Matter 138
4.3.4 Soil Texture 139
4.4 Heavy Metal Concentration Level in River and Shinko Sites Soil 142
4.4.1 Iron Concentration in Soil 142
4.4.2 Zinc Concentration in Soil 143
4.4.3 Manganese Concentration in Soil 144
4.4.4 Copper Concentration in Soil 145
4.4.5 Cadmium Concentration in Soil 146
4.4.6 Chromium Concentration in Soil 147
4.4.7 Lead Concentration in Soil 149
4.4.8 Nickel Concentration in Soil 150
4.5 Heavy Metal Contamination/Pollution of River and Lake Sites Soils 155
4.5.1 Heavy Metal Pollution Index Assessment 155
4.6 Heavy Metal Concentration Level in Vegetables of River and
Shinko Lake Irrigation Sites
159
4.6.1 Concentration of Iron in Vegetables 159
xii
4.6.2 Concentration of Zinc in Vegetables 162
4.6.3 Concentration of Manganese in Vegetables 165
4.6.4 Concentration of Copper in Vegetables 167
4.6.5 Concentration of Cadmium in Vegetables 169
4.6.6 Concentration of Chromium in Vegetables 172
4.6.7 Concentration of Lead in Vegetables 175
4.6.8 Concentration of Nickel in Vegetables 178
4.7 Heavy Metal Transfer Factor from Soil into Vegetables 185
4.7.1 Cabbage 188
4.7.2 Lettuce 188
4.7.3 Amaranthus 188
4.7.4 Tomatoes 189
4.8 Distribution of Heavy Metal Concentration in Water, Soil and
Vegetables of River Benue and Shinko Lake of Geriyo Catchment
192
4.9 Health Risk Index Evaluation Assessment for Intake of Heavy
Metal in Vegetables through Food Chain Transfer Pathway
197
4.9.1 Daily Intake of Metal (DIM) 197
4.9.2
Health Risk Index Evaluation in Vegetables of River
Benue for Body Weights of 60kg and 32.5kg 198
4.9.2.1 Risk from River Benue Irrigated Cabbage 198
4.9.2.2 Risk from River Benue Irrigated Lettuce 200
4.9.2.3 Risk from River Benue Irrigated Amaranthus 203
4.9.2 .4 Risk from River Benue Irrigated Tomatoes 205
4.9.3
Health Risk Index Evaluation in Vegetables of Shinko
Lake for Body Weights of 60kg and 32.5kg
209
4.9.3.1 Risk from Shinko Lake Irrigated Cabbage 209
4.9.3.2 Risk from Shinko Irrigated Lettuce 211
4.9.3.3 Risk from Shinko Irrigated Amaranthus 212
4.9.3.4 Risk from Shinko Irrigated Tomatoes 214
4.9.4 Health Risk Index Evaluation in Vegetables of River
Benue for Body Weight of 50kg and 22.5kg
219
xiii
4.9.5
Health Risk Index Evaluation in Vegetables of River
Benue for Body Weight of 40kg and 12.5kg
221
4.9.6
Health Risk Index Evaluation in Vegetables of Shinko for
Body Weight of 50kg and 22.5kg
223
4.9.7
Health Risk Index Evaluation in Vegetables of River
Benue for Body Weight of 40kg and 12.5kg
225
4.9.8
Summary of Heath Risk Evaluation for Vegetables of
Geriyo Catchment Area
228
C CHAPTER 5 CONCLUSION, CONTRIBUTION TO KNOWLEDGE AND
RECOMMENDATIONS
5.1 Conclusion 232
5.2 Contribution to knowledge 235
5.3 Recommendations 236
REFERENCES 238
APPENDIX 275
xiv
LIST OF FIGURES
Figures Pages
2.1 Surface Water Spray Application Technique at Geriyo Irrigation Site 27
2.2 Furrow Water Application Technique at Geriyo Irrigation Site 27
3.1 Map of Nigeria Showing Adamawa State 66
3.2 Map of Geriyo Watershed Showing Sampling Points of Soil, Water and
Vegetables
68
3.3 Water Sources used for Irrigation in Geriyo Catchment Area 69
3.4 Analytical Framework for Water Analysis 70
3.5 Analytical Framework for Soil and Vegetable Analysis 71
3.6 Digested Water Samples for Laboratory Analysis 73
3.7 Cabbage, Lettuce, Amaranthus and Tomatoes Farm of Geriyo site 74
3.8 Single Analyte Dissolved Oxygen Meter for Testing Oxygen in Water 76
3.9 Digital Meter for pH and EC Measurement of Water Samples 76
3.10 Digested Soil and Vegetable Samples for Analysis on AA240FS 79
3.11 AA240 FS Varian Model, Germany 79
3.12 Shimadzu Model UV 160 UV/VIS Spectrophotometer 84
3.13 Buck Scientific Flame Photometer 210VGP Model USA 85
3.14 Sequential Atomic Absorption AA240FS Running Samples 88
4.1 Variation of Turbidity at Seven Locations of River Benue of Geriyo
Watershed
102
4.2 Variation of Turbidity at Seven Locations of Shinko Lake of Geriyo
watershed
102
4.3 Variation of pH at Seven Locations of River Benue Sampling Points 104
4.4 Variation of pH at Seven Locations of Shinko Lake Sampling Points 104
4.5 Variation of Chloride Concentration at Seven Sampling Points of River
Benue Water Samples
106
4.6 Variation of Chloride concentration at seven sampling points of Shinko
Lake Water Samples
107
xv
4.7 Variation of Dissolved Oxygen at Seven Sampling Points of River Benue
Water
108
4.8 Variation of Dissolved Oxygen at Seven Sampling Points of Shinko Lake
Water
109
4.9 Variation of BOD at Seven Sampling Locations of River Benue Water 110
4.10 Variation of BOD at Seven Sampling Locations of Shinko Lake Water 111
4.11 Variation of COD at Seven Sampling Locations of River Benue Water 112
4.12 Variation of COD at Seven Sampling Locations of Shinko Lake Water 113
4.13 Variation of Heavy Metal Levels in River Benue Site Soil Compared to
Control and FAO/WHO Standard Limit
151
4.14 Variation of Heavy Metal Levels in Shinko Lake Site Soil Compared to
Control and FAO/WHO Standard Limit
151
4.15 Mean Concentration Level of Fe in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
160
4.16 Mean Concentration Level of Fe in Vegetables of Shinko Lake Irrigation
Site Compared to Control and FAO/WHO Standard Limit
161
4.17 Mean Concentration Level of Zn in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
163
4.18 Mean Concentration Level of Zn in Vegetables of Shinko Irrigation Site
Compared to Control and FAO/WHO Standard Limit
163
4.19 Mean Concentration Level of Mn in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
166
4.20 Mean Concentration Level of Mn in Vegetables of Shinko Irrigation Site
Compared to Control and FAO/WHO Standard Limit
166
4.21 Mean Concentration Level of Cu in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
168
4.22 Mean Concentration Level of Cu in Vegetables of Shinko Irrigation Site
Compared to Control and FAO/WHO Standard Limit
168
4.23 Mean Concentration Level of Cd in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
170
xvi
4.24 Mean Concentration Level of Cu in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
170
4.25 Mean Concentration Level of Cr in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
174
4.26 Mean Concentration Level of Cr in Vegetables of Shinko Lake Irrigation
Site Compared to Control and FAO/WHO Standard Limit
174
4.27 Mean Concentration Level of Pb in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
176
4.28 Mean Concentration Level of Pb in Vegetables of Shinko Lake Irrigation
Site Compared to Control and FAO/WHO Standard Limit
176
4.29 Mean Concentration Level of Ni in Vegetables of River Benue Irrigation
Site Compared to Control and FAO/WHO Standard Limit
179
4.30 Mean Concentration Level of Ni in Vegetables of Shinko Lake Irrigation
Site Compared to Control and FAO/WHO Standard Limit
179
4.31 Transfer Factor of Heavy Metals from Soil to Vegetables of River Benue
Irrigation Site
187
4.32 Transfer Factor of Heavy Metals from Soil to Vegetables of Shinko Lake
Irrigation Site
187
4.33 Distribution of Heavy Metals in Water, Soil and Vegetables of River
Benue Irrigation Site
193
4.34 Distribution of Heavy Metals in Water, Soil and Vegetables of Shinko
Lake Irrigation Site
194
4.35 Health Risk Index for Adult and Children from Intake of Heavy Metals in
Cabbage from River Benue Irrigation Site
200
4.36 Health Risk Index for Adult and Children from Intake of Heavy Metals in
Lettuce from River Benue Irrigation Site
202
4.37 Health Risk Index for Adult and Children from Intake of Heavy Metals in
Amaranthus from River Benue Irrigation Site
205
4.38 Health Risk Index for Adult and Children from Intake of Heavy Metals in
Tomatoes from River Benue Irrigation Site
207
xvii
4.39 Health Risk Index for Adult and Children from Intake of Heavy Metals in
Cabbage from Shinko Lake Irrigation Site
210
4.40 Health Risk Index for Adult and Children from Intake of Heavy Metals in
Lettuce from Shinko Irrigation Site
212
4.41 Health Risk Index for Adult and Children from Intake of Heavy Metals in
Amaranthus from Shinko Irrigation Site
214
4.42 Health Risk Index for Adult and Children from Intake of Heavy Metals in
Tomatoes from Shinko Irrigation Site
216
xviii
LIST OF TABLES
Tables Page
2.1 Summary of Research Observations from Literature Review 62
3.1 Wavelengths and Appropriate Working Condition of Buck 210VGP
AAS
85
3.2 Oral Reference Dose of Metal Ingestion per Day for Vegetables 92
4.1 Mean Physicochemical Properties of Impacted River Benue Water at
Seven Sampling Locations of Geriyo Watershed
120
4.2 Mean Physicochemical Properties of Impacted Shinko Lake Water at
Seven Sampling Locations of Geriyo Watershed
121
4.3 Guideline for the Interpretation of Water Quality for Irrigation 122
4.4 One Way ANOVA of Physicochemical, and Heavy Metal in River
Benue Water Samples
123
4.5 One Way ANOVA of Physicochemical and Heavy Metal in Shinko
Lake Water Samples
124
4.6 Mean Concentration Level of Heavy Metals in River Benue Water at
Seven Sampling Locations in (mg/L)
134
4.7 Mean Concentration Level of Heavy Metals in Shinko Lake Water at
Seven Sampling Locations in (mg/L)
135
4.8 Most Common Classification of Soil pH 137
4.9 Physicochemical Properties of Soils of River Benue and Shinko Lake,
and Control Site Soil
141
4.10 Mean Concentration of Heavy Metals in River Benue and Shinko Sites
Soils taken Before and After Planting of Vegetables in Compared to
Control Site Soil in (mg/kg)
152
4.11 International Threshold Values of Heavy Metals Concentration in Soils 152
4.12 Pearson Correlation of Heavy Metals in River Benue Water and Soil 153
4.13 Pearson Correlation of Heavy Metals in Shinko Lake Water and Soil 154
4.14 Significance of Interval of Contamination/Pollution for MPI 155
xix
4.15 Degree of Soil Contamination/Pollution of River Benue and Shinko
Irrigation Sites
158
4.16 Summary of Heavy Metal Concentration in the Studied Vegetables 181
4.17 Mean Concentration of Heavy Metals in Vegetables and Fruit Irrigated
at River Benue and Shinko Lake Sites Compared with Control and
FAO/WHO Maximum Permitted Levels in Vegetables
182
4.18 Paired Sample T- test Summary on Heavy Metals in River Benue Soil
and Irrigated Vegetables
183
4.19 Pearson’s Correlation Analysis Summary for Heavy Metals in River
Benue Soil and Vegetables of Shinko Site
183
4.20 Paired Sample T- test Summary of Heavy Metals in Shinko Lake Site
Soil and Irrigated Vegetables
184
4.21 Pearson’s Correlation Analysis for Heavy Metals in Shinko Lake Soil
and Vegetables
184
4.22a Summary of Metal Transfer Factor as Observed in this Study 189
4.22b Heavy Metal Transfer Factor from Soil to Vegetables of River Benue
and Shinko Sites Soils
191
4.23a Summary of Heavy Metal Distribution in Water, Soil and Vegetables
observed in this Study
195
4.23b Distribution of Heavy Metal Concentrations in Water, soil and
Vegetables of River Benue and Shinko Lake Irrigation Sites
196
4.24 Effects of Excessive Intake of Heavy Metal on Human Health 203
4.25 Daily Intake of Metals (DIM) and Health Risk Index (HRI) for Heavy
Metal Caused by Consumption of 345g/d and 232g/d of Vegetables
Grown with Polluted River Water and Soil on Adult and Children of
60kg and 32.5kg Body Weights
208
4.26 Daily Intake of Metals (DIM) and Health Risk Index (HRI) for Heavy
Metal Caused by Consumption of 345g/d and 232g/d of Vegetables
Grown with Polluted Shinko Lake Water and Soil on Adult and
Children of 60kg and 32.5kg Body Weights
218
xx
4.27 Daily Intake of Metals (DIM) and Health Risk Index (HRI) of Heavy
Metal Caused by Consumption of 345g/d and 232g/d of Vegetables
Grown with Polluted River Benue Water and Soil on Adult and
Children of 50kg and 22.5kg Body Weights
220
4.28 Daily Intake of Metals (DIM) and Health Risk Index (HRI) of Heavy
Metal Caused by Consumption of 345g/d and 232g/d of Vegetables
Grown with Polluted River Benue Water and Soil on Adult and
Children of 40kg and 12.5kg Body Weights
222
4.29 Daily Intake of Metals (DIM) and Health Risk Index (HRI) of Heavy
Metal Caused by Consumption of 345g/d and 232g/d of Vegetables
Grown with Polluted Shinko Lake Water and Soil on Adult and
Children of 50kg and 22.5kg Body Weights
224
4.30 Daily Intake of Metals (DIM) and Health Risk Index (HRI) of Heavy
Metal Caused by Consumption of 345g/d and 232g/d of Vegetables
Grown wit Polluted Shinko Lake Water and Soil on Adult and Children
of 40kg and 12.5kg Body Weights
227
4.31 Summary of Health Risk Index for Body Weights of 60, 50, 40kg and
32.5, 22.5 and 12.5kg for Adult and Children for Ingestion of 345g/d
and 232g/d of Vegetables Grown with Polluted River Benue Water
230
4.32 Summary of Health Risk Index for Body Weights of 60, 50, 40kg and
32.5, 22.5 and 12.5kg for Adult and Children for Ingestion of 345g/d
and 232g/d of Vegetables Grown with Polluted Shinko Lake Water
231
xxi
LIST OF ABBREVIATIONS
APHA American Public Health Association
AWWA American Water Works Association
AAS Atomic Absorption Spectrophotometer
ANOVA Analysis of Variance
FAO Food and Agricultural Organization
WHO World Health Organization
USEPA United State Environmental Protection Agency
USDA United State Department of Agriculture
IWMI International Water Management Institute
EU European Union
USA United State of America
UK United Kingdom
FEPA Federal Environmental Protection Agency
RBW River Benue Water
TW Tape Water
CABB Cabbage
CSS Control Site Soil
RBWSS River Benue Site Soil
SHLSS Shinko Lake Site Soil
TOM Tomatoes
AMA Amaranthus
LETT Lettuce
HRI Health Risk Index
DIM Daily Intake of Metal
MPI Metal Pollution Index
VCF Vegetable Concentration Factor
PCF Plant Concentration Factor
xxii
RfD Reference Dose
ND Not Detected
NTU Nephelometric Turbidity Unit
StD Standard
StE Standard Error
Std Standard deviation
UV Ultraviolet
EDTA Ethylenediamine Tetra acetic acid
PFGE Pulsed Field Gel Electrophoresis
FAS Ferrous Ammonium Sulphate
BHIA Brain Heart Infusion Agar
DIC Differential Interference Contrast
IMS/FA Immunomagnetic Separation/Filtration Assay
PBS Phosphate Buffered Saline
DAPI Diamino – 2 – Phenyldole
KHP Potassium Hydrogen Phthalate
BOD Biochemical Oxygen Demand
COD Chemical Oxygen Demand
DO Dissolved Oxygen
TDS Total Dissolved Solids
TS Total Solids
TSS Total Suspended Solids
AL Alkalinity
CL Chloride
Ca Calcium
EC Electrical Conductivity
T Temperature
OM Organic Matter
TN Total Nitrogen
P Phosphorus
