ABSTRACT
This work reports the effects of well depth on the physicochemical and microbial properties of hand dug wells water in villages close to Rivers Niger and Benue in Lokoja, Nigeria. Wells up to 2.8 m deep and 300 m away from the rivers were studied in both the dry and wet seasons. Analyses of samples of well water from the villages (Shintaku, Ganaja and Gbobe) and Lokoja metropolis showed that the total suspended solid (TSS), total dissolved solid (TDS), total solid (TS), alkalinity, total hardness (TH) and turbidity were in the ranges of 13 – 450, 57 – 905, 10 – 170, 11.5 – 18, 202 – 818 mgdm-3 and 0.611 – 140 NTU respectively. Biochemical oxygen demand (BOD), chemical oxygen demand (COD) and dissolved oxygen (DO), were in the ranges of 0.1 – 0.45, 108 – 346 and 0.08 – 0.75 mgdm-3 respectively. Also the ranges of electrical conductivity (EC) and pH recorded were: 53. 35 – 98.5 μScm-1 and 5.9 – 7.5. While those of ammonia, nitrate and phosphate in the water were in the ranges 0.01 – 0.3, 3.9 – 43 and 1.5 – 14.95 mgdm-3, respectively in the dry season of 2014. TSS, TDS, TS, alkalinity, TH and turbidity of the well water samples showed the mean values of 13 – 450, 57 – 905, 10 – 170, 59 – 131, 130 – 404 mgdm-3 and 0.611 – 140 NTU respectively. BOD, COD and DO recorded the highest concentration ranges of 0.2 to 31, 60 to 818 and 0.9 to 1.2 mgdm-3 respectively. However, the ranges of EC and pH of the sample were: 0.611 – 140 NTU and 5.8 – 7.15, respectively. Ammonia, nitrate and phosphate were in the ranges of 3.1 – 14.5, 7.5 – 65 and 3.1-13.5 mgdm-3, respectively in the wet season of 2014. The water samples had detectable levels of Cu, Cd, Ni, Mn, Pb and Zn, but all the samples have metal contents far below the permissible limits, except for the Cd content which was above in some of the water samples. By using the multiple tube fermentation technique, the well water from all the sites had faecal contamination with bacteria pathogens such as Klebsiella spp, Escherichia coli, Enterobacter spp., Serantia spp. and Citrobacter spp. During the wet season, it was found that the amounts of nitrate, turbidity, microbial isolate and pH values of the well water were found to increase with depth of the well. And the value of TS and TDS also increases positively with the proximity of the wells to the rivers in wet season. Therefore, careful consideration and planning is needed in construction of the wells. This suggests that wells must be up to 15 m deep and 300 m distance away from the river so as to be free from pollution.
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TABLE OF CONTENTS
Title Page i Declaration ii Certification iii Dedication iv Acknowledgement v Abstract vi List of Tables vii List of Figure xi Abbreviation xiv
CHAPTER ONE
1.0 INTRODUCTION 1
1.1 Water 1
1.2 Justification 4
1.3 Aim of the Work 4
1.3.1 Objectives 4
CHAPTER TWO
2.0 LITERATURE REVIEW 6
2.1 Water 6 2.1.1 Sources of water 6 2.1.2 River Niger 7 2.1.3 River Benue 7 2.2 Wells 8 2.2.1 Well contamination 8
2.3 Groundwater 9
2.3.1 Groundwater pollution 12
2.3.2 Survival of microorganisms in groundwater 12 2.4 Physico-Chemical Properties of Water 13 2.4.1 pH of Water 13
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2.4.2 Improving the pH of water 13 2.4.3 Total dissolved solids 14 2.4.4 Turbidity 15 2.4.5 Electrical conductivity 15 2.4.6 Hardness of water 16 2.4.7 Potential health effect of hard water 16 2.4.8 Nitrate in water 17 2.4.9 Potential health effect of nitrate 17 2.4.10 Alkalinity 19 2.4.11 Chemical oxygen demand (cod) 19 2.4.12 Biological oxygen demand (bod) 19 2.5. Metallic Pollutants 20
2.5.1 Effects of heavy metals 20
2.6 Bacteriological Analysis 23
2.6.1 Total coliforms 24
CHAPTER THREE 3.0 MATERIALS AND METHOD 29 3.1 Description of the Study Area 29 3.2 Sampling site 30 3.2.1 Sample collection 30 3.3 Preparation of Aqueous Stock Solutions 31 3.3.1 Calibration curves 32 3.4. Determination of Physico-Chemical Parameters 33 3.4.1 Determination of temperature 33 3.4.2 Determination of pH 33 3.4.3 Determination of conductivity 33 3.4.4 Determination of turbidity 33 3.4.5 Determination of total hardness 34 3.4.6 Determination of total dissolved solids 34 3.4.7 Determination of chemical oxygen demand (cod) 35 3.4.8 Determination of biochemical oxygen demand (bod) 36 3.4.9 Determination of nitrate, phosphate 36 3.4.10 Determination of dissolved oxygen 36
3.4.11 Determination of total alkalinity 36
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3.5 Procedure for Water Digestion 37 3.6 Atomic Absorption Spectrophotometric Analysis 37 3.7. Bacteriological Analysis 38 3.7.1 Presumptive coliform test 38 3.7.2 Identification of isolate 38 CHAPTER FIVE 5.0 DISCUSSION 75 5.1 Characterization of Well Water Samples 75 5.1.1 pH of the well water samples 75 5.1.2 Temperature of the well water samples 76 5.1.3 Electrical conductivity of the well water samples 76 5.1.4 Total hardness (TH) of the well water samples 77 5.1.5 Chemical oxygen demand of the well water samples 79 5.1.6 Biological oxygen demand of the well water samples 80 5.1.7 Dissolved oxygen demand of the well water samples 81 5.1.8 Total dissolved solid of the well water samples 82 5.1.9 Total suspended solid of the well water samples 82 5.1.10 Total solids of the well water samples 83 5.2 Chemical Properties of the Well Water Samples Near River Niger and Benue in Lokoja, Nigeria 83 5.2.1 Nitrate 83 5.2.2 Phosphate 84 5.2.3 Ammonia 85 5.3. Heavy Metal of the Well Water Samples 85 5.4 Microbial Characterization of the Well Water Samples 87 5.5 Effects of Distance and Depth on Water Quality 89 5.6 Statistical Data Analysis 90
CHAPTER SIX
6.0 SUMMARY, CONCLUSION AND RECOMMENDATION 92
6.1 Summary 92
6.2 Conclusion 92
6.3 Recommendations 93 Reference 94
CHAPTER ONE
1.0 INTRODUCTION
1.1 WATER
Water, after air, is the most essential commodity to the survival of life. Human life depends, to a large extent, on water. It is used for an array of activities; chief among these being drinking, food preparation, as well as for sanitation purposes. In as much as safe drinking water is essential to health, a community lacking in a good quality of this commodity will be saddled with a lot of health problems which could otherwise be avoided (Miller and Junior, 1997). Water covers 70.9% of the earth’s surface, and is vital for all known forms of life. On earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapour and precipitations. Oceans hold 97% of surface water, 2.4% for glaciers and polar ice caps, and, 0.6% for other land surface water such as rivers, lakes and ponds. A very small amount of the earth‘s water is contained within biological bodies and manufactured products (Wikipedia, 2010). Groundwater is of major importance and is intensively exploited for private, domestic and industrial uses. According to Ajibade et al. (2011), 90% of the population in Nigeria depends largely on hand-dug wells and boreholes. Water is necessary for sustainable economic development in a country like Nigeria. Hand dug wells have been the sources of water for people in Nigeria for ages. Some of these wells are dug close to rivers. And literature shows that rivers are the major transporting means for different contaminants into groundwater and lakes (Sina et al., 2009).
The preference of groundwater as a source of drinking water in rural areas is due to its relatively better quality than river water (Obiri-Danso et al., 2009). Historically, rural
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settlement is being determined by the water source which is stream, river and spring (Okeola et al., 2010). The inhabitants of these settlements rely on underground water often being within a few metres below the surface, which are exploited by well digging. Access to safe drinking water is a basic human need and is a fundamental human right, crucial for poverty reduction and eradication. According to a report by United Nations (2003), this situation forces people to consume water directly from the rivers and ponds and this represents a high risk to the consumers‘ health. According to World Health Organization (WHO, 2000), in the next thirty years alone, accessible water is unlikely to increase more than ten percent (10%) but the earth‘s population is projected to rise by approximately one-third. Unless the efficiency of water use rises, this imbalance will reduce the quality of water services, reduce the conditions of health of people and deteriorate the environment and the world. Rivers are the major transporting means for different contaminant into other resources like groundwater and lake (Karbassi, 2007). By passing water through the ground, its quality will change and this might be related to humans or natural phenomenon. . Generally, shallow groundwater is affected more by contamination compared to deep groundwater (Kinzelbach, 1989). Groundwater moves downwards due to the pull of gravity. It can also move up because it will flow from higher- pressure areas to lower pressure areas. The rate of groundwater flow is permeability (pore space) environmental protection agencies (EPA, 1994). The ultimate distance to which water pollution will occur in a groundwater depend on a number of complex and interlocking factors, namely wet and dry weather, (Kinzelbach, 1989). .
Heavy metals such as zinc, copper, cadmium and manganese are important in small quantities for biological processes in plants and animals. They also occur naturally in soil,
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water and the atmosphere. However, when they are discharged in large quantities from sewage, industrial and agricultural run-offs and ultimately find their way into water bodies including oceans and river, they constitute an increasing hazard to humans through the food chain. (Tay et al., 2011). The water pollution by heavy metals has become a scientific concern in many countries because of their toxicity to human health and biological systems (Anazawa et al., 2004). Each pollutant has its own health risk profile. Metal concentrations in groundwater may also increase due to discharges from various anthropogenic sources. Small quantities of certain heavy metals are nutritionally essential for a healthy life. Some of these are referred to as trace elements (e.g. iron, copper, manganese and zinc). Heavy metals become toxic when they are not metabolized by the body and accumulate in the soft tissues. These metals may enter the human body through food, water and air, or absorption through the skin when they come in contact with humans in agriculture and pharmaceutical industry. Heavy metals become more hazardous when they are ingested in large quantities and these might causes public health problems (Anazawa et al., 2004).
Faecal contamination with bacteria pathogens such as Klebsiella spp, Escherichia coli, Entrobacter spp, Serantia spp. and Citrobacter spp. such contaminant are responsible for the cause of communicable enteric disease, some of the pathogenic micro-organisms that cause these diseases may be present in water. Drinking water or using it in food preparation may then result in new cases of infection (Anazawa et al., 2004). The pathogenic agents involved include bacteria, viruses, and protozoa, which may cause diseases that vary in severity from mild gastroenteritis to severe and sometimes fatal diarrhoea, dysentery, hepatitis, or typhoid fever and most of them are widely distributed throughout the world (Mara et al., 1989). Faecal contamination of drinking water is only one of several faeco-oral mechanisms by which disease can be transmitted from one person to another or, in
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some cases, from animals to people (APHA, 1998) reported that bacteria in water are generally not present individually but as clumps or in association with particulate matter.
1.2 Justification
The quality of well water in villages close to rivers Niger and Benue in Lokoja Kogi State have become a major health concern. In addition, an inhabitant depends majorly on wells water, which have doubtful water quality especially during the wet season. The villages near rivers Niger and Benue in Lokoja are not connected to pipe water supply system causing most people to depend on other alternative sources of water such as hand dug wells constructed in many households close to the rivers with doubtful water quality. These alternative sources are, to a large extent, exposed to contaminants such as bacteria, heavy metals, nitrates and other salts which have resulted in polluting the water.
1.3 Aim of the Work
The overall aim of this work was to determine the effects of proximity and depth on the quality of water from wells of villages near river Niger and Benue on water quality in Lokoja.
1.3.1 Objectives
The above aim has been achieved by the following set of objectives:
I. To compare the effect of well depth on the water quality;
II. To determine the physicochemical and microbial properties of the well water in villages (Gbobe, Shintaku and Ganaja) near rivers Niger and Benue in Lokoja, Nigeria;
III. To compare the effect of well depths on the water quality in Lokoja metropolis;
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IV. To comparing the quality of water samples collected from the wells of the villages near the flood plain with those from Lokoja metropolis;
V. To determine the effects of distance on the quality of water samples
VI. To study and compare the quality of water as a function of depth;
VII. To correlate the result of the well water quality as a function of distance to the rivers and well depths;
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