ABSTRACT
The groundwater quality indices of 12 randomly selected boreholes in Enugu North Senatorial District in Enugu State, south-east Nigeria have been studied. Using standard methods by American Public Health Association, American Water Works Association; World Environmental Federation (APHA-AWWA-WEF) and the Association of Official Analytical Chemists (AOAC), 22 physicochemical parameters were determined in triplicates at monthly intervals for three months in dry season and then repeated in rainy season. The parameters and the range of values obtained during dry season include: BOD5(3.14–6.37 mg/L), COD(5.8–10.51 mg/L), temperature(29.0-31.9 C), phosphate(0.12-0.87 mg/L), nitrate(1.24-8.72 mg/L), sulphate(20.10-24.34 mg/L), pH(4.900-7.500), E.C(10.0–410.0 μS/cm), total acidity(0.06 – 1.24 mg/L), total alkalinity(28.0–22.10 mg/L), total hardness ( 100.0 – 140.1 mg/L), TSS(70.0–270.0 mg/L), TDS(0.00–210.0 mg/L), TS(70.0–390.0 mg/L), turbidity(3.4 –50.0 mg/L), Na(0.0–21.28 mg/L), K(0.0–12.03 mg/L), Cu(0.0–23.01 mg/L), Fe(0.0–11.03 mg/L), and Zn(0.01–3.00 mg/L). During rainy season, the parameters in the 12 samples revealed the following ranges: BOD5(2.88 – 6.10 mg/L), COD(3.49–7.45 mg/L), temperature(29.0-31.9 C), phosphate(0.30–10.60 mg/L), nitrate(1.20–120.0 mg/L), sulphate(0.0–100.0 mg/L), pH(4.900-7.500), E.C(10.0- 360.0 μS/cm), total acidity(0.10-10.5 mg/L), total alkalinity(10.0-52.1 mg/L), total hardness(100-130 mg/L), TSS(100.0-280.0 mg/L), TDS(0.0-260.0 mg/L), TS(110.0- 560.0 mg/L), turbidity(3.80-56.0 mg/L), Na(0.0-21.28 mg/L), K(1.32-15.11 mg/L), Cu (0.03-28.37 mg/L), Fe(0.0-12.29 mg/L), and Zn(0.02-3.61 mg/L). The mean values of the parameters were compared with standard guideline values recommended by World Health Organisation (W.H.O.), Nigerian Standard for Drinking Water Quality (NSDWQ), National Agency for Food and Drug Administration and Control (NAFDAC) and the European Union (EU) for drinking water. Seasonal variations of the parameters in the samples were observed. The mean values of BOD5 and temperature in all the samples were above the standard values. The rainy season nitrate values in some samples and phosphate mean values were higher than recommended values. There was a drop in pH during rainy season with the range generally acidic in both seasons. Turbidity in some samples was above the guideline value. A rainy season increase in total acidity (with a corresponding rainy season drop in total alkalinity), total hardness; sulphate and Zn values was observed. Cd and Pb were not detected in all the samples studied. The mean values of Cu and Fe increased in rainy season and were above the recommended guideline values in both seasons. K mean value increased in rainy season slightly above the standard guideline value. Recovery analyses were performed for the metals to validate the accuracy of the methods and instruments as well as the reliability of the results obtained. A two-way analysis of variance (ANOVA; using SPSS Windows Version 20) performed on the data obtained showed statistically significant variations between the 12 borehole water physicochemical parameters in dry season as well as in rainy season. Post hoc tests of multiple comparisons were conducted to specify the patterns of variability between the samples. An overall physicochemical Water Quality Index (WQI) for each borehole was computed and used in the groundwater rating. Levene’s T3 test revealed no significance difference between the dry season overall physicochemical WQI and rainy season overall physicochemical WQI t (18.67) = – 1.27, p = .22. Pearson correlation coefficient showed linear relationships in some of the physicochemical parameters studied.
CHAPTER ONE INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Water is fundamental to life as well as nature. It is not just an important natural resource, it is also essential to all life forms. Its use and effects on life, environment, agriculture and industry are extensive so much so that they may never be exhausted. Starting with a few of the critical roles water performs in life for instance, one can say that water is one of the vital forces that drive life. This is evident in its critical functions in life producing (as well as furnishing) processes such as organic reactions in the body leading to cell replication and metabolism, respiration (in plants and animals) and photosynthesis in plants which provides the oxygen for animal respiration, including man. Also, water is a habitat for all aquatic life forms- plankton, amphibians, fish (most of which exclusively live in water), even some mammals like whales and dolphins (marine mammals). Since it is a basic requirement
for plant photosynthesis, water is widely used for irrigation in agriculture.1 Apart from
its key role in biological (and biochemical) processes and agriculture, water finds its application in industry to be as central as it is in other spheres of life on earth. It is used in hydro-electric-power generation which is a renewable source of clean energy, food processing, fire extinguishing, transportation recreation (such as swimming), laundry and even chemical uses. It suffices to say that being a universal solvent 2; and with its vast uses, one can say that water is an essential driver of global economy. It is said to be the most abundant chemical compound on the earth surface, covering about three quarters of the earth surface (the total volume of water on earth has been
given as approximately 1,338,000,000 km3). 3- 5
Despite its abundance, only three percent of water (which exists as fresh water and partly as ponds, rivers and streams; most of which are trapped in glaciers and polar caps) is potable for human use and consumption since the other bulky 97 percent exists as ocean which is highly saline.
Naturally, water is a unique substance that can exist as solid, liquid and gas forms. 2 At standard temperature and pressure, water is liquid (density: 1,000 kg/m3); it freezes into solid ice at 0oc (density of 917 kg/m3) and at sea level, it boils at 100oc (specific heat capacity: 4181.3 J/(kg·K) and heat of vaporization: 40.65 kJ·mol−1 ). The maximum density of water occurs at 3.98 °C. 6 Its molecule is polar and composed of a single oxygen atom (16O) and two hydrogen atoms (1H and a little of
2H depending on natural source) with an H-O-H bond angle of about 1050 2.
It has been said that the human body needs between one to seven litres of water per day to avoid dehydration, 7 depending on factors such as humidity, temperature, body activity, 8 and so on. Pregnant and breastfeeding women need extra fluid to keep them hydrated. 9 Water meant for drinking should be safe by being free of contaminants. It is said to be polluted if foreign substances (oxygen
demanding substances, diseases causing agents, inorganic chemicals, synthetic organic chemicals such as pesticides and industrial wastes, sediments from land erosion, radioactive wastes or energy such as waste heat) are present in such a degree that it can not be used for a specified purpose. 2 Sources of these pollutants have been classified as resulting from Municipal waste (or domestic effluents), agricultural discharge, and mining and industry. 3 It is thus imperative to check the various sources of water supply for drinking and domestic purposes so as to analyse for their purity.
Natural sources of water include rain-water, surface water (streams, rivers, sea, etc) and groundwater. Water supply facilities include water purification facilities, water tanks, water towers, water pipes including old aqueducts, water wells, cisterns for rainwater harvesting, water supply networks, etc. Borehole water, (which is obtained from ground source) is one of the common sources of water for drinking and other domestic and industrial purposes around the world.
In Nigeria, there are laws governing the use of water resources. These are contained in the Constitution of the Federal Republic of Nigeria 1999 as “Nigerian Laws Governing the water sector. They include among others: The Water Resources Act 1993, The National Water Resource Institute Act, River Basins Development Authorities Act, National Inland Waterways Authority Act, The Various State Water Board Acts, The National Resources Conservation Council Act, etc. For instance, the “Water Resources Act 101 of 1993” vests on the Federal Government of Nigeria through the Federal Ministry of Water Resources, the rights to regulate, develop, and license all water operators in Nigeria. This includes planning, development, and usage of Nigeria’s water resources, ensuring quality, quantity, distribution, use and management of water, ensuring application of appropriate standards and techniques for investigation, use control, protection, management and administration of water
resources, facilitating technical assistance and rehabilitation for water supplies etc. 10
It is therefore important to constantly investigate the quality of water from various sources around us as this will serve as a contribution towards national development.
1.2 Drinking Water Quality
The characteristic of water supply that will influence its suitability for a specific use is referred to as water quality. Quality is defined by certain physical, chemical and biological characteristics. These characteristics provide the basic
parameters for the analysis of water for various purposes. In Nigeria and other parts of the world, these parameters provide a basic framework for references to be made to globally approved standards. Stakeholders in the water sector and outside the country have reached a consensus on the parameters and standard for water quality (including drinking water and water for agricultural and industrial purposes). For example, the Nigerian Standard for Drinking Water Quality (NSDWQ) established in 2007 was developed with reference to World Health Organisation (WHO) guidelines for
drinking water quality (3rd Edition), Nigeria Industrial Standard for Potable Water and
Natural Mineral Water and the National Guidelines and standards for Water Quality in Nigeria. NSDWQ which was approved by the Standards Organisation of Nigeria (SON) subdivided the parameters for determining water quality into physical/organoleptic, chemical organic and inorganic constituents, disinfectants and disinfectant by-products, radionuclide and microbial parameters. 11 These parameters and their allowable limits (maximum permitted limits) are tabulated below:
1.2.1 Parameters and Maximum Allowable Limits
Table 1.1 Physical / Organoleptic Parameters
| Parameter | Unit | Maximum Permitted Levels | Health Impact |
| Colour | TCU | 15 | None |
| Odour | – | Unobjectionable | None |
| Taste | – | Unobjectionable | None |
| Temperature | 0oCelsius | Ambient | None |
| Turbidity | NTU | 5 | None |
1.2.2 Chemical Parameters
Table 1.2 – Inorganic Constituents
| Parameter | Unit | Maximum | Health Impact | Notes | |
| Permitted | |||||
| Aluminium (Al) | mg/L | 0.2 | Potential | Neuro-degenerative | Note 1 |
| disorders | |||||
| Arsenic (As) | mg/L | 0.01 | Cancer, | ||
| Barium | mg/L | 0.7 | Hypertension | ||||||
| Cadmium (Cd) | mg/L | 0.003 | Toxic to the kidney | ||||||
| Chloride (Cl) | mg/L | 250 | None | ||||||
| Chromium (Cr6+) | mg/L | 0.05 | Cancer | ||||||
| Conductivity | μS/cm | 1000 | None | ||||||
| Copper (Cu2+) | mg/L | 1 | Gastrointestinal disorder, | ||||||
| Cyanide (CN-) | mg/L | 0.01 | Very toxic to the thyroid and the nervous system | ||||||
| Fluoride (F-) | mg/L | 1.5 | Fluorosis, Skeletal tissue (bones and teeth) morbidity | ||||||
| Hardness (as CaCO3) | mg/L | 150 | None | ||||||
| Hydrogen | Sulphide | mg/L | 0.05 | None | |||||
| (H2S) | |||||||||
| Iron (Fe2+) | mg/L | 0.3 | None | ||||||
| Lead (Pb2+) | mg/L | 0.01 | Cancer, interference with Vitamin D metabolism, affect mental development in infants, toxic to the central and peripheral nervous systems | ||||||
| Magnesium (Mg2+) | mg/L | 0.20 | Consumer acceptability | ||||||
| Manganese (Mn2+) | mg/L | 0.2 | Neurological disorder | ||||||
| Mercury (Hg+) | mg/L | 0.001 | Affects the kidney | and | central | ||||
| nervous system | |||||||||
| Nickel (Ni) | mg/L | 0.02 | Possible carcinogenic | ||||||
| Nitrate (NO3-) | mg/L | 50 | Cyanosis, and asphyxia („blue- baby syndrome”) in infants under 3 months syndrome”) in infants under 3 months | ||||||
| Nitrite (NO2-) | mg/L | 0.2 | Cyanosis, and asphyxia (‘blue- baby syndrome’) in infants under 3 months | ||||||
| pH | – | 6.5-8.5 | None | ||||||
| Sodium (Na+) | mg/L | 200 | None | ||||||
| Sulphate (SO4 | 2- | ) | mg/L | 100 | None | ||||
| Total | Dis | solved | mg/L | 500 | None | ||||
| Solids | |||||||||
| Zinc (Zn) | mg/L | 3 | None | ||||||
Table 1.3 Organic Constituents
| Parameter | Unit | Maximum Permitted Levels | Health Impact |
| Detergents | mg/L | 0.01 | Possibly carcinogenic |
| Mineral oil | mg/L | 0.003 | Possibly carcinogenic |
| Pesticides | mg/L | 0.01 | Possibly carcinogenic |
| Phenols | mg/L | 0.001 | Possibly carcinogenic |
| Poly Aromatic Hydrocarbons | mg/L | 0.007 | Possibly carcinogenic |
| Total Organic Carbon or Oxidisability | mg/L | 5 | Cancer |
1.2.3. Disinfectants and their By-products
Table 1.4 Disinfectants and their by-products
| Parameter | Unit | Maximum Permitted Levels | Health Impact | Note |
| Free residual chlorine | mg/L | 0.2 – 0.25 | None | Note 2 |
| Trihalomethanes Total | mg/L | 0.001 | Cancer | Note 2 |
| 2,4,6-trichlorophenol | mg/L | 0.02 | Cancer | Note 2 |
Note 2: For chlorinated water only.
Drinking water providers shall increase the amount of residual chlorine during epidemics or special cases according to instructions of Ministry of Health.
1.2.4 Radioactive Constituents
The presence of the following contaminants shall not exceed limits specified in Table
1.5.
Table 1.5 – Radioactive Limits
| Parameter | Unit | Maximum | Health | Notes |
| Permitted | Impact | |||
| Levels | ||||
| Radionuclides | Bq/L | 0.1 | Cancer |
1.2.5. Microbiological Requirements
Table 1.6 Microbiological Limits
| Parameter | Unit | Maximum | Health Impact | |||
| Permitted Levels | ||||||
| Total Coliform count | cfu/mL | 10 | Indication of faecal contamination | |||
| Thermo | tolerant | Coliform | or | cfu/100 mL | 0 | Urinary track infections, bacteraemia, |
| E.coli | meningitis, diarrhea, (one of the main cause of morbidity and mortality among | |||||
| children), acute renal failure and | ||||||
| haemolytic anaemia | ||||||
| Faecal streptococcus | cfu/100 mL | 0 | Indication of recent faecal contamination | |||
| Clostridium perfringens spore | cfu/100 mL | 0 | Index of intermittent faecal contamination | |||
SOURCE: Nigerian Standard for Drinking Water approved by Standard
Organisation of Nigeria, 2007.
Over a billion people worldwide do not have access to safe water 2 and some of the problems facing the Nigerian water sector include poor water quality due to pollution and sanitation issues. 3 The Federal Government of Nigeria through the Millennium Development Goals (MDGs) Programme is partnering with State Ministry of Water Resources, e.g. the Enugu State Rural Water and Sanitation Agency (ENRUWSA) as well as other organisations such as the United Nations International Children Emergency Fund (UNICEF), in finding lasting solutions to the
menace of safe water scarcity. Through this partnership, borehole water schemes are being carried out in different parts of the country. For instance in Nsukka, the electro- mechanical systems of the urban water boreholes have been rehabilitated and one new borehole has been drilled along Enugu Road, Nsukka. Enugu State government is committed to water and environmental sanitation to such a degree as to compel companies producing toxic waste water to mount plants that will treat their waste water. A United Nations (UN) report observed that water-borne diseases are endemic
in certain parts of Africa’s most populous country (Nigeria) 4 but UNICEF
emphasizes that the occurrence of diarrhoea, a major childhood killer in Nigeria, could decline by 15 percent if water quality was improved. It is pertinent therefore to conduct research in the water sector to provide data on the quality of water in parts of the state.
1.3. STATEMENT OF PROBLEMS
• In the bid to meet the water demand of the ever-growing population in Enugu North Senatorial District and its environs, efforts without substantial impact have been made by individuals, governments, and corporate bodies towards supply of potable water for the masses. Some of these efforts include the construction of borehole water supply systems (whose purity is seldom taken
serious 4) in communities and urban towns (and as such close to anthropogenic
contamination source).
• Many people within the urban towns and rural communities in Enugu North
Senatorial District still suffer from lack of stable potable water supply.
• In 2006, United Nations report stated that “there is enough water for everyone4
unfortunately, only a few have access to good quality water.
• It has been estimated that by 2025 more than half of the world population will be facing water-based vulnerability. 3
1.4 SIGNIFICANCE OF THE STUDY
The significance of this study includes provision of:
• Baseline information on borehole water quality for Enugu North Senatorial
District catchment area.
• A framework to assess the on-going study of vulnerability of borehole water supply in Enugu State to contamination and the major operational or infrastructure problems that may make future contamination likely. This will
help to enhance substantial impact in efforts made towards supply of potable water to the ever-growing population in Enugu State.
• A reference for future planning, assessment and monitoring of progress made in the water sector in Nigeria.
• More insight into the existing water safety parameters with the view to facilitate disease surveillance due to possible water toxins. This will help to reduce the number of people dying of water related diseases as more than
25,000 people are said to die daily due to water related diseases.6
• Supportive information towards the ongoing Environment Impact Assessment (EIA) with the view to reducing indiscriminate contamination of natural waters.
1. 5 OBJECTIVES OF THE STUDY
• The general purpose of this study is to assess the quality of borehole water in Enugu North Senatorial District, Enugu State, Nigeria. To achieve this aim, the objectives of the study shall be to:
• Determine twenty-two physicochemical parameters in water samples collected from twelve boreholes selected from the seven Local Government Areas (LGAs) in the study area in dry season and rainy season.
• Compare the results obtained with the World Health Organisation (WHO) standard for potable water and/or Nigerian Standard for Drinking Water quality (NSDWQ).
• Establish the comparative ground water qualities of various towns and communities in the study area.
• Measure the strength of association of the water quality parameters.
• Make necessary recommendations based on the findings of the research.
1.6 SCOPE OF STUDY
• Borehole water samples collected from twelve different towns/communities covering seven LGAs in Enugu North Senatorial District at different times during the research period.
• A total of twenty-two physicochemical parameters determined in the samples based on the specific objectives of this study. These parameters were carefully selected to cover the following:
► General degree of water pollution,
► Pollution due to agricultural/fertilizer inputs,
► Parameters due to soil types and geological differences,
► Heavy Metals: possible inputs from water sources especially waste-water percolation from industrial processes.
This material content is developed to serve as a GUIDE for students to conduct academic research
PHYSICOCHEMICAL STUDIES OF BOREHOLE WATER IN ENUGU NORTH SENATORIAL DISTRICT ENUGU STATE NIGERIA
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