ABSTRACT
he physicochemical and heavy metal assessment of water from selected boreholes in Kaura Namoda has been studied for the purpose of ascertaining the water quality of the boreholes. Twenty selected boreholes were sampled three times each at two weeks interval between the months of April and May, 2013. Parameters which included temperature, pH, turbidity, electrical conductivity, total dissolved solids (TDS), sulphate, phosphate, nitrate, chloride, fluoride, copper, lead, zinc, cadmium, iron and manganese were determined using standard methods. The results obtained when compared with the WHO, NSDW and USEPA standards for drinking water showed that the parameters which include turbidity, pH, electrical conductivity, TDS, phosphate, nitrate and fluoride had values that were within the maximum permissible limits in all the twenty boreholes sampled while parameters which include sulphate, chloride, cadmium, iron, hardness, lead, manganese and zinc were detected at levels above the permissible limit for drinking water in some of the boreholes sampled. Copper was below detectable level in all the boreholes except in one borehole with value within the maximum permissible limits. Therefore, not all the boreholes investigated had parameters that were in conformity with the WHO 2006, NSDW 2007 and USEPA 2012 recommended permissible limits for drinking water hence possible adverse effect due to consumption of the water containing high level of these parameters may occur among the inhabitants of this study area especially in the cases of the boreholes where lead and cadmium were detected above the permissible limits if they bio-accumulate beyond the tolerable concentrations in the body.
TABLE OF CONTENTS
itle page i
Declaration ii
Certification iii
Dedication iv
Acknowledgment v
Abstracts vi
Table of Contents vii
List of Tables xiv
List of Figures xv
List of Appendices xvii
List of Abbreviations xvii
CHAPTER ONE
1.0 INTRODUCTION 1
1.1 Background Study 1
1.2 The Importance of Water Quality Assessment 2
1.3 Groundwater Pollution 4
1.4 Justification 6
1.5 Aim and Objectives 7
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CHAPTER TWO
2.0 LITERATURE REVIEW 8
2.1 The Properties of Soil and its Influence on Groundwater 11
2.2 Groundwater and the Aquifer 12
2.3 Factors Affecting the Quality of Groundwater 14
2.4 Sources of Groundwater Pollution 15
2.4.1 Agricultural sources of groundwater pollution 15
2.4.2 Industrial sources of groundwater pollution 19
2.4.3 Domestic of groundwater pollution 21
2.4.4 Natural sources of groundwater pollution 21
2.5 Indicators of Groundwater Quality and their Significance 22
2.5.1 Heavy metals 22
2.5.2 Heavy metals and their significance 23
2.5.3 Some physicochemical indicators of water quality 30
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CHAPTER THRE
3.0 EXPERIMENTAL RESARCH AND METHODOLOGY 42
3.1 Preamble 42
3.2 Description of the Study Area 42
3.3 Sampling Collection and Preservation 45
3.4 Analysis of Physicochemical Parameters 48
3.4.1 Temperature determination 48
3.4.2 Turbidity determination 48
3.4.3 Potential of hydrogen (pH) determination 48
3.4.4 Electrical conductivity determination 48
3.4.5 Total dissolved solid determination 49
3.4.6 Determination of sulphate, nitrate and phosphate 49
3.4.7 Spectrometric determination of fluoride 49
3.4.8 Determination of chloride 50
3.4.9 Determination of total hardness 51
3.5 Preparation of Samples and Stock Solutions 54
3.5.1 Digestion of water sample for metal analysis 54
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3.5.2 Preparation of stock solutions 55
3.6 Atomic Absorption Spectroscopy Analysis and calibration curve 56
3.7 Theory of Atomic Absorption Spectrophotometer (AAS) 57
3.8 Principle of Operation of Photometer 58
3.9 Statistical Analysis 59
CHAPTER FOUR
4.0 RESULTS 60
4.1 Determination of Physicochemical Parameters 60
4.1.1 Temperature 60
4.1.2 pH 60
4.1.3 Conductivity 60
4.1.4 Total dissolved solids 66
4.1.5 Turbidity 66
4.2 Determination of Chemical Parameters 66
4.2.1 Chloride 66
4.2.2 Fluoride 74
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4.2.3 Nitrate 74
4.2.4 Sulphate 74
4.2.5 Phosphate 74
4.2.6 Hardness 74
4.3 Heavy Metals Determination 75
4.3.1 Zinc 75
4.3.2 Manganese 75
4.3.3 Iron 75
4.3.4 Lead 83
4.3.5 Cadmium 83
4.3.6 Copper 83
CHAPTER FIVE
5.0 DISCUSSION 86
5.1 Physicochemical Parameters 86
5.1.1 Temperature 86
5.1.2 pH 86
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5.1.3 Conductivity 87
5.1.4 TDS 87
5.1.5 Turbidity 88
5.1.6 Chloride 88
5.1.7 Fluoride 89
5.1.8 Nitrate 90
5.1.9 Sulphate 91
5.1.10 Phosphate 91
5.1.11 Hardness 92
5.2. Heavy Metals 93
5.2.1 Zinc 93
5.2.2 Manganese 94
5.2.3 Iron 94
5.2.4 Lead 95
5.2.5 Cadmium 95
5.2.6 Copper 96
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CHAPTER SIX
SUMMARY OF FINDINGS, CONCLUSION AND RECOMMENDATIONS
6.1 Summary of the Findings 98
6.2 Conclusion 99
6.3 Recommendations 99
References 101
Appendices 109
CHAPTER ONE
INTRODUCTION
1.1 Background Study
Water is life and is known to be next to oxygen in the order of importance in the sustenance of life. In fact, about two-thirds of human body is made of water. This colourless, odourless and tasteless liquid is essential for all forms of growth and development and is the basic need for sustaining human economic activities. Not only does water support a wide range of activities, it also plays a central symbolic role in rituals throughout the world and is considered a divine gift by many religions. It is indeed one of the earth’s most precious resources (Ayoade and Akintola, 1999; Padma and Namrata, 2009).
Availability of water in the desired quantity and quality, at the right time and place, has been the key to the survival of all civilizations. No other natural resource has had overwhelming influence on human history. As the human population increases, as people express their desire for a better living, as the economic activities continues to expand in scale, the demand for fresh resources continues to grow. Although water is a renewable resource, its availability in space (at a specific location) and time (at different periods of the year) is limited by climate, geographical and physical conditions (Chapman, 1996). Clean water is such scarce resource in the world that only a tiny fraction of the planet’s abundant water is available as fresh water. Of the total water on earth only about 97% of it is available as saltwater. More than 2% is
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locked up in ice cap or glaciers. Only less than 1% of the earth’s total volume of water is available as drinking water. The fresh water we use comes from two sources; surface and groundwater. Precipitation that does not soak into the ground or return to the atmosphere by evaporation or transpiration is surface water. The subsurface area where all available soil or rock is filled by water is groundwater (Padma and Namrama, 2009).
Although water is essential for human survival, many are denied access to sufficient potable drinking water supply. Globally, about 1.1billion people rely on unsafe drinking water resources from lakes, rivers and open wells. The majority of these are in Asia (20%) and sub-Sahara Africa (42%). Furthermore, 2.4 billion people lack adequate sanitation worldwide (WHO/UNICEF, 2008). Nevertheless, the key to increase human productivity and long life is good quality drinking water. The provision of good quality water is often regarded as an important means of improving health. In recent time, some parts of the world have been making encouraging progress in meeting the Millennium Development Goals (MDG) on water, but serious disparities remain. Lack of access to improved drinking water is still a serious problem in large portion of Asia and Sub-Sahara Africa (WHO/UNICEF, 2008).
1.2 The Importance of Water Quality Assessment
Water quality assessment process is an evaluation of the physical, chemical and biological nature of a water body in relation to intended uses particularly as it affects human health (Chapman, 1996). The quality of water may be described in terms of concentration and state (dissolved or particulate) of some or all the organic and
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inorganic materials present in the water, together with certain physical characteristics of water. It is determined by in-situ measurements and by examination of water samples on site or in laboratory. The main elements of water quality monitoring are, therefore, on-site measurement, the collection and analysis of water samples, the study and evaluation of the analytical results, and the reporting of the findings. The results of analyses performed on a single water sample are only valid for the particular location and time at which the sample is taken (Marky and Raman, 2011).
Unsatisfactory water supply and unwholesome sanitation conditions can result in poor human health. This portends the fact that there are very strong relationship between water and health (WHO/UNICEF, 2004). It is a natural resource whose scarcity or poor quality can cause a chain of unpleasant situations for mankind, especially in developing countries like Nigeria where access to improved drinking water is still a serious problem. There are many ways in which poor water quality and sanitary conditions can give rise to poor health (McJunkin, 1982; WHO, 2008). Water-related diseases are responsible for 80% of all illness/deaths in developing countries, killing more than 5 million people every year (UNESCO, 2007). Water borne diseases, as well as water related diseases which include cholera and other diarrheal diseases, as well as other water related parasitic diseases like schistosmiasis, guinea worm and river blindness are very common (WHO, 2006). In developing countries, thousands of children under the age of five die every day due to drinking of contaminated water (WHO, 2006). Thus lack of safe drinking water supply, basic sanitation and hygienic practice are associated with high morbidity and mortality. In fact, one of the goals of
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the United Nations Millennium Development Goals (MDG) is to reduce persistent poverty and promote sustainable development worldwide especially in developing countries through the improvement of drinking water supply and sanitation. The MDG target for water is to half, by 2015, the proportion of people without sustainable access to safe drinking water and basic sanitation (UNESCO, 2007). The WHO (2008) estimates that if these improvements were to be achieved in Sub-Sahara Africa alone, 434,000 child deaths due to diarrhoea alone would be averted annually.
1.3 Groundwater and Pollution
Groundwater exploitation has been with man way back in the ancient times. The civilizations of the ancient time had its success anchored on water supplies from groundwater as well as surface water. It is reported that in 1183 BC, crusade prisoners in Egypt constructed wells from excavated rocks which they called Joseph’s well to ensure the citadels and water supply. The drilling instead of the usual digging of wells began in the 12th century with successful drilling of well at Artois of France in 1226 (Osiakwan, 2002).
In the basement rocks, groundwater occurs in the weathered regolith and the fractured zones which sieves as the aquifer zone and usually occurs at depth ranging from 0m to a maximum of 60m. This underground water is protected from surface contamination by a layer of clay and fine grained sediments. The level of groundwater in the borehole may undergo change due to the recharge and discharge. The rate at which a borehole is recharged may vary due to variation in rainfall events, or as influent flows from nearby
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streams and rivers. A geological material that stores and transmits groundwater freely is known as an aquifer (Back et al., 1993).
Groundwater, like any other water resource, is not just of public health and economic values (Armon and Kitty, 1994). Water pollution has become a question of considerable public and scientific concern in light of the evidence of their toxicity to human health and biological systems. Heavy metals receive particular concern considering their strong toxicity even at low concentrations (Marcovecchio et al., 2007). Groundwater may contain some impurities or contaminants, which may be above the permissible limit as recommended by WHO even without human activities or disturbances. Natural contaminants can come from many conditions in the water shed or in the ground. This is because water moving through rocks or soil may pick up magnesium, calcium, chlorides, fluorides while some groundwater contain dissolved elements such as arsenic, boron, selenium, lead, cadmium, iron and manganese ( Alloy and Ryres, 2009).
These natural contaminants become a health hazard when they are present in high concentration. Also, groundwater is often polluted by human activities such as the use of fertilizers, animal manure, herbicides, insecticides and pesticides. Other sources of groundwater contamination can originate in the house or other forms such as dormitories, poorly built septic tanks and sewage systems for household wastewater. Leaking or abandoned underground storage tanks and improper disposal or storage waste chemical spills at local industrial sites also contribute to pollution of
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groundwater. Abandoned wells that have not been plugged or dismantled provide a potential pathway for water to flow directly from the surface into the groundwater. Open wells can become contaminated by the working fluids such as grease and oil from the pump or contaminants from the surface if the well cap is not tightly closed or if the lining is cracked or corroded (USEPA, 2007).
1.4 Justification
The major source of drinking water for the inhabitants of Kaura Namoda Local Government Area in recent time is the untreated groundwater obtained from boreholes that are drilled across the entire study area mostly by government agencies and individuals. Most of these boreholes are newly constructed and there is no existing information on their water quality. Meanwhile, the area is known for its intensive agricultural activities and most of these boreholes are located within the vicinities of farm lands and therefore could be contaminated. Also, the area is characterized by massive underlying rocks which could contain minerals capable of impacting on the groundwater. It is on this background that the water quality assessment of these boreholes became necessary so as to ascertain their suitability for drinking purposes by comparing with the WHO, NSDW and USEPA standards for drinking water.
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1.5 Aim and Objectives of the Study
The aim of this study was to access the quality of borehole water sourced from selected boreholes in Kaura Namoda Local Government Area. To achieve this aim, the objectives were as follows:
i. To determine the level of heavy metals in borehole water which include: zinc (Zn), copper (Cu), iron (Fe), cadmium (Cd), lead (Pb) and manganese (Mn).
ii. To determine the physicochemical properties of the underground water (borehole) which include: temperature, turbidity, total dissolved solid, electrical conductivity, pH, phosphates, sulphates, nitrates, total hardness, chlorides and fluorides.
iii. To compare the level of heavy metal and physicochemical parameters obtained from the analysis with the WHO, NSDW and USEPA standards for drinking water to ascertain the suitability of the water for drinking purposes.
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