Quality Characteristics of Underground Water Resources in Nkanu East and Nkanu West Local Government Areas of Enugu State, Nigeria.
CHAPTER ONE
Objective of Study
There are yet no reported physicochemical or bacteriological studies of underground water resources in Nkanu East and Nkanu West Local government Areas. Therefore we set out to analyze borehole water samples from these areas in order to ascertain the potability and safety of the water by comparing the concentration levels with set standards and to procure the present quality status as baseline data for future periodic monitoring of the underground water quality in this area.
CHAPTER TWO
Literature Review
Water
Water is the most abundant substance in living systems, making up 70% or more of the weight of most organisms. Its unique physical properties, which include the ability to solvate a wide range of organic and inorganic
molecules, derive from it’s dipolar structure and exceptional capacity for forming hydrogen bonds. An excellent nucleophile, water is a reactant or product in many metabolic reactions. It has a slight propensity to dissociate into
hydroxide ions and protons.
Properties of Water
- Water is a dipole, a molecule with electrical charge distributed asymmetrically about its structure. The strongly electronegative oxygen atom pulls electrons away from the hydrogen nuclei, leaving them with a partial positive charge, while its two unshared electron pairs, constitute a region of local negative charge
- Water has a high dielectric constant of 78.5. It therefore decreases the force of attraction between charged and polar species relative to water-free environments with lower dielectric constants
Water, whose two lone pairs of Sp3 electrons bear a partial negative charge, is an excellent nucleophile. Nucleophilic attack by water generally results in the cleavage of the amide, glycoside, or ester bonds that hold biopolymers together - Water has a higher melting point, boiling point, and heat of vaporization than most other common solvents. These properties are a consequence of attractions between adjacent water molecules that give liquid water great internal cohesion
- Water is an amphiprotic solvent. That is, it behaves as an acid in the presence of basic solutes and as a base in the presence of acidic solutes
- Water is a highly polar molecule, capable of forming hydrogen bonds with itself and with solutes due to possession of very different electronegativities of hydrogen and oxygen atoms [4].
- Water is a good solvent for polar (hydrophilic) solutes, with which it forms hydrogen bonds, and for charged solutes, with which it interacts electrostatically [4].
- Water is both the solvent in which metabolic reactions occur and a reactant in many biochemical processes, including hydrolysis, condensation, and oxidation-reduction reactions .
Uses of Water
- The high specific heat of water is useful to cells and organisms because it allows water to act as a “heat buffer”, keeping the temperature of an organism relatively constant as the temperature of the surroundings fluctuates and as heat is generated as a byproduct of metabolism.
- The high degree of internal cohesion of liquid water, due to hydrogen bondings, is exploited by plants as a means of transporting dissolved nutrients from the roots to the leaves during the process of transpiration.
The density of ice is lower than that of liquid water and as a result ponds freeze from the top down, and the layer of ice at the top insulates the water below from frigid air, preventing the pond from freezing solid.
CHAPTER THREE
Sample Collection
Water samples were collected from boreholes (taps) located in various villages in Nkanu East and Nkanu West Local Government Areas, in Enugu State, South-east of Nigeria. The villages are Isiogbo Nara, Nara Unateze, Mbulu Owo, Amechi Idodo, Amurri, Agbani, Amodu Awkunanaw, Umueze and Akpugo as shown in Fig 3.1 and Table 3.1. The water samples were collected after adequately flushing the service line (tap) and allowing the water to reach the ambient temperature. The samples were taken in new 2-litre polyethylene cans which were first rinsed with AnalaR grade 1:1 HCl
Method of Analysis
Turbidity
HANNA Turbidimeter LA 2000 model was used. 10 mL of water sample was measured into a 10 mL sample cell. The sample cell was placed in the turbidimeter and the Nephelometric turbidity value was obtained and recorded.
Temperature
This was measured at the sampling point. JENWAY 470 conductivity meter model was used for this purpose.
Colour
HACH colourimeter BL 890 model was used for determination of colour. 10 mL of water sample was measured into a 25 mL sample cell. The sample cell was placed into a colourimeter and the colour unit shown by the colourimeter was recorded.
Total dissolved solid
JENWAY 470 conductivity meter model was used for the determination of total dissolved solid. 20 mL of sample was measured into a 25 mL sample cell. The sample cell was taken to the conductivity meter and the value
obtained was recorded.
CHAPTER FOUR
Results and Discussion
Tables 4.1-4.6 give the concentrations of different parameters analyzed and the corresponding WHO guideline values.
Turbidity
The turbidity level ranges from BDL – 98.0 NTU with water sample from Amodu Awkunanaw having the highest turbidity value of 98 NTU. While six samples are below recommended WHO permissible level of 5 NTU [45], samples from Amechi Idodo, Mbulu Owo, Isiogbo Nara and Amodu Awkunanaw exceeded this value. The high values recorded for turbidity may be as a result of the dissolution of solid phases into the underground water. It may also be as a result of precipitated calcium carbonate in hard waters, aluminium hydrate in treated waters and precipitated iron oxide in corrosive water [35]. Turbidity in water can stop light from reaching submerged plants and can raise water temperature [31]. Turbidity may also contain particles that are toxic or help to accumulate toxic substances in water. Turbidity, therefore, may be judged both as a physical parameter- because it causes aesthetic and psychological objections by the consumer, and a microbiological parameter- because it may harbor pathogens and impede the effectiveness of disinfection.
CHAPTER FIVE
Conclusion and Recommendation
Underground water drawn from wells and boreholes constitute a major source of water supply in many African countries including Nigeria. In these circumstances, the water is usually untreated. This appears to be the case for the water samples analyzed. Notwithstanding the elevated levels of iron, chromium, cadmium, lead and total coliform in the samples, analyte concentrations were generally moderate indicating that sewage, leaching of waste, fertilizers, animal waste and mineralization has not adversely affected the quality of the studied water samples. The data procured are baseline and are representative of the geological strata of the area. Based on the results obtained, the following recommendations are necessary:
- Sources of underground water should be sited faraway from pit latrines, sewage systems and incinerators to avoid introduction of pathogenic microorganism into the water which can cause water borne diseases.
- Concerted efforts should be made by the populace to monitor the level of waste disposal so as to ensure clean and potable drinking water system.
- Government should enlighten the people especially the rural dwellers on the need to maintain a healthy environment.
- There should be a quality control plan (quarterly, monthly, yearly) by the government to test the water so as to ensure the safety of the water supply.
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