i
QUALITY CHARACTERISTICS OF UNDERGROUND WATER RESOURCES IN NKANU EAST AND NKANU WEST LOCAL GOVERNMENT AREAS OF ENUGU STATE, NIGERIA.
CHUKWUDI, IFEOMA .D. PG/M.Sc/10/57611
DEPARTMENT OF PURE AND INDUSTRIAL CHEMISTRY, UNIVERSITY OF NIGERIA, NSUKKA.
SUPERVISOR: DR. C.O. B. OKOYE
AUGUST, 2013 i
TITLE PAGE
QUALITY CHARACTERISTICS OF UNDERGROUND WATER RESOURCES IN NKANU EAST AND NKANU WEST LOCAL GOVERNMENT AREAS OF ENUGU STATE, NIGERIA.
BY
CHUKWUDI, IFEOMA .D. PG/M.Sc/10/57611
A RESEARCH PROJECT SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF THE DEGREE OF MASTER OF SCIENCE IN ANALYTICAL CHEMISTRY IN THE DEPARTMENT OF PURE AND INDUSTRIAL CHEMISTRY, UNIVERSITY OF NIGERIA, NSUKKA.
AUGUST, 2013
ii
APPROVAL PAGE
This research has been approved for the Department of Pure and Industrial Chemistry, Faculty of Physical Sciences, University of Nigeria, Nsukka .
By
______Prof.P.O.Ukoha Dr. C.O. B. Okoye Head of Department Project Supervisor
Date______Date______
______External Examiner
Date ______iii
CERTIFICATION
Chukwudi Ifeoma, a post graduate student in the Department of Pure and
Industrial Chemistry, with the registration number PG/M.Sc/10/57611, has satisfactorily completed the requirements for course and research work for the degree of Master of Science in Analytical Chemistry. The work embodied in this project is original and has not been submitted in part or whole for any other diploma or degree of this or any other university.
______Prof. P.O. Ukoha Dr. C.O.B. Okoye Head of Department Project supervisor Date ______Date______
iv
DEDICATION
This project is dedicated to the faithful God. v
ACKNOWLEDGEMENT
My inexpressible thanks goes first to God who saw me through this programme. I also appreciate Him for His provision and wisdom throughout the period of this programme.
I am indebted to my ebullient and indefatigable supervisor, Dr. C.O.B
Okoye for his eagerness to correct and direct accordingly. I also owe my sincere appreciation to my head of department, Prof. P.O. Ukoha.
I am most grateful to my parents and siblings for their support. I owe my appreciation to the staff and management of Federal Ministry of Water
Resources, Regional Water Quality Laboratory, Enugu where the analysis was carried out. My special thanks goes to Mr. Innocent Obi for his unalloyed support. Finally I am grateful to my friends and well wishers who in one way or the other contributed to the success of this work.
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ABSTRACT Physicochemical and bacteriological analyses of underground water resources in Nkanu East and Nkanu West Local Government Areas of Enugu state, Nigeria were carried out to evaluate the potability and quality of the rural water supplies and to provide baseline data for future quality assessment. Underground water samples were collected from ten different boreholes in Nkanu East and Nkanu West LGAs. The parameters measured include temperature, colour, pH, electrical conductivity, turbidity, total dissolved solids, total hardness, calcium hardness, magnesium hardness, total alkalinity, chloride, sulphate, phosphate, nitrate, sodium, potassium, lead, chromium, copper, cadmium, nickel, iron, zinc and total coliform. The water showed near neutral pH (6.4- 8.2) favourably comparable to the WHO recommended range of 6.5-8.5, with moderate permanent hardness of 2.5-289 mg/L. Conductivity and total dissolved solids values for Amechi Idodo (4360 μs/cm, 2650 mg/L) and Mbulu Owo (4880 μs/cm, 2930 mg/L) were higher than the WHO guideline values of 1660 μs/cm and 1000 mg/L, respectively. Concentrations of most trace metals and all anions were below the WHO guideline values. However, iron,cadmium and chromium occurred at levels slightly above the WHO permissible limit. Total coliform count in Amechi Idodo and Mbulu Owo exceeded the WHO guideline value of zero. The underground waters studied are good for drinking provided they are boiled to remove microbial contamination.
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TABLE OF CONTENTS Pages
Title Page ------i Approval Page ------ii Certification ------iii Dedication ------iv Acknowledgement ------v Abstract ------vi Table of Contents ------vii List of Tables ------xi List of Figures ------xii
CHAPTER ONE 1.0 Introduction ------1 1.1 Underground water quality ------1 1.2 Background of Study ------2 1.3 Scope of Study ------3 1.4 Objective of Study ------4
CHAPTER TWO 2.0 Literature Review------5 2.1 Water ------5 2.1.1 Properties of water ------5 2.1.2 Uses of Water ------6 2.2 Types of water resources ------7 2.2.1 Underground water ------7 2.2.2 Surface water ------8 2.2.3 Water in the atmosphere ------12 viii
2.3 Pollution ------12 2.3.1 Water pollution ------13 2.3.1.1 Organic pollutants ------13 2.3.1.2 Inorganic pollutants ------15 2.3.1.3 Sediments pollutants ------16 2.3.1.4 Radioactive materials ------16 2.3.1.5 Thermal pollutants ------17 2.3.2 Underground water pollution/pollutant ------17 2.3.2.1 Point-source pollution ------19 2.3.2.2 Non-point source pollution ------19 2.3.2.3 Chemical pollution ------21 2.3.2.4 Biological pollution ------22 2.3.2.5 Physical/Natural pollution ------24 2.4 Water Analysis ------25 2.4.1 Physical examination ------25 2.4.1.1 Temperature ------25 2.4.1.2 Turbidity ------25 2.4.1.3 pH------27 2.4.1.4 Total dissolved solids ------27 2.4.1.5 Conductivity ------28 2.4.1.6 Colour ------28 2.4.2 Chemical examination ------28 2.4.2.1 Hardness ------28 2.4.2.2 Alkalinity ------30 2.4.2.3 Calcium ------30 2.4.2.4 Magnesium ------31 2.4.2.5 Chloride ------31 2.4.2.6 Nitrate ------31 ix
2.4.2.7 Phosphate ------32 2.4.2.8 Potassium ------32 2.4.2.9 Sulphate ------33 2.4.2.10 Sodium ------33 2.4.2.11 Cadmium ------34 2.4.2.12 Chromium ------35 2.4.2.13 Copper ------36 2.4.2.14 Iron------37 2.4.2.15 Lead------38 2.4.2.16 Nickel ------38 2.4.2.17 Zinc ------39 2.4.3 Microbiological examination ------` 39
CHAPTER THREE 3.0 Materials and Methods ------41 3.1 Sample collection------41 3.2 Method of analysis ------43 3.2.1 Turbidity ------43 3.2.2 Temperature ------43 3.2.3 Colour ------43 3.2.4 Total dissolved solid ------43 3.2.5 pH ------44 3.2.6 Conductivity ------44 3.2.7 Total alkalinity ------44 3.2.8 Total hardness ------45 3.2.9 Calcium ------46 3.2.10 Magnesium ------47 3.2.11 Chloride ------47 x
3.2.12 Nitrate ------48 3.2.13 Sulphate ------49 3.2.14 Phosphate ------49 3.2.15 Sodium ------50 3.2.16 Potassium ------50 3.2.17 Heavy metals determination ------51 3.2.18 Bacteriological examination ------52 CHAPTER FOUR 4.0 Results and Discussions ------53 4.1 Turbidity ------55 4.2 Colour ------55 4.3 Conductivity ------57 4.4 Total dissolved solid ------57 4.5 pH ------58 4.6 Total hardness, calcium hardness and magnesium hardness ------59 4.7 Total alkalinity ------61 4.8 Nitrate ------62 4.9 Phosphate ------62 4.10 Sulphate------63 4.11 Chloride------63 4.12 Sodium and potassium ------64 4.13 Heavy metals ------67 4.14 Total coliform ------69 Conclusion and Recommendation ------69 References ------71 xi
LIST OF TABLES
3.1: Sample code and sample location ------41
4.1: WHO standard values for drinking water ------53
4.2: Physicochemical quality of underground water in Nkanu East and Nkanu West Local Government Areas, Enugu State, Nigeria ------54
4.3: Colour and turbidity of water sample------56 4.4: Conductivity and total dissolved solid of water sample ------58
4.5: Total hardness, magnesium hardness and calcium hardness of water sample ------60
4.6: Metal concentrations (mg/L) of water sample ------66
xii
LIST OF FIGURES
3.1: Map of Nkanu East and Nkanu West LGAs ------42 4.1 Bar-chart showing correlation between colour and turbidity ---- 56 4.2 Bar-chart showing correlation between conductivity and total dissolved solids ------58 4.3: Bar-chart showing correlation between total hardness, magnesium hardness and calcium hardness ------61
1
CHAPTER ONE
1.0 Introduction
1.1 Underground water quality
Water is the matrix of life and forms the bulk of the weight of the living cells. The resources of usable water have been diminishing and are unable to meet the variety of needs of modern civilization. Water as the carrier of pathogenic microorganisms, can cause immense harm to public health.
Waterborne diseases include typhoid and paratyphoid fever, dysentery and cholera, polio and infectious hepatitis [1].
Many developing countries are witnessing a stage of development where water from shallow wells and boreholes are gradually supplementing the original sources of drinking water (surface water). The preference for underground water to surface water is borne out of the belief that before underground water can be distributed as tap water it must always be subjected to some purification, while in practice, underground waters are filtered by natural processes as they pass through columns of soils, sands, strata, or sedimentary layers of rocks and are usually clear of solid materials as they come from the aquifer, particularly if they are deep seated ones. The intricate pore spaces or water passage ways of the aquifer materials act as a fine filter and remove small particles of clay or any other fines [2]. Organic materials decay or are destroyed in transit. Thus, the dirtiest and most polluted sewage 2 water may become clear of suspended/particulate solid materials once it has gone through a thick bed of sand or geologic and pedologic units. As a result of this natural self-cleansing of polluted water by deep-seated aquifers, physical and biological aspects of pollution may not pose serious problems in underground waters [2].
Thus, underground water may not be treated before use and is believed to be free from pollution. In spite of all this, underground waters may have pollutants that not only depend on the geology, pedology, and mineralogy of the formations it flows through but also on the constituent pollutants/contaminants in the water that recharges the underground water.
Unsatisfactory colour and taste are easily detected and are good indicators for underground waters of poor quality. Some underground waters taste of iron, others may have a disagreeable odor. Borehole waters must, as a rule, be analyzed for chemical contaminants before the water is distributed and supplied to households [2].
1.2 Background of Study
The area of study is Nkanu East and Nkanu West. A Local Government
Area in Enugu State, Nigeria, Nkanu East borders Ebonyi State to the east. Its
Headquarters is Amagunze. It is a rural area with a population of about 148,
774 and land mass of approximately 795 km2.. Nkanu West has its
Headquarters at Agbani. It has an area of 225 km2 and a population of 146,695. 3
The major occupation in these areas is farming. The various communities making up the two local government areas live in small villages, which still have considerable natural surroundings. Although there are springs and streams, most of the communities rely on boreholes for their water supply due to proximity and modernity [3].
Due to increased use of fertilizers and pesticides in this areas part of which is leached into the underground water through the soil, there is increased risk of pollution of these boreholes. Enugu, the state of study was previously mined for coal and underground water pollution is an ever present risk in areas of mining. Also most of the people use pit toilets which are sources of underground water pollution [2].
1.3 Scope of Study
Samples of water from ten boreholes in the two LGAs specifically in
Amechi Idodo, Mbulu Owo, Umueze, Agbani, Ugbawka, Isiogbo Nara,
Akpugo, Amurri, Nara Unateze and Amodu Awkunanaw are to be collected.
Physicochemical, bacteriological and trace metal analysis comprising of temperature, colour, pH, electrical conductivity, turbidity, total dissolved solids, total alkalinity, total hardness, calcium, magnesium, chloride, nitrate, phosphate, sulphate, sodium, potassium, total coliform, lead, copper, zinc, chromium, cadmium, and nickel are to be undertaken and values obtained are to be compared with World Health Organization (WHO) guideline values. 4
1.4 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.
5
CHAPTER TWO
2.0 Literature Review
2.1 Water
Water is the most abundant substance in living systems, making up 70% or more of the weight of most organisms [4]. 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 [5].
2.1.1 Properties of Water
v 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 [5].
v 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 [5].
v Water, whose two lone pairs of Sp3 electrons bear a partial negative
charge, is an excellent nucleophile. Nucleophilic attack by water 6
generally results in the cleavage of the amide, glycoside, or ester bonds
that hold biopolymers together [5].
v 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 [4].
v 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
[6].
v 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].
v 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].
v Water is both the solvent in which metabolic reactions occur and a
reactant in many biochemical processes, including hydrolysis,
condensation, and oxidation-reduction reactions [4].
2.1.2 Uses of Water
v 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 7
organism relatively constant as the temperature of the surroundings
fluctuates and as heat is generated as a byproduct of metabolism[4].
v 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
[4].
v 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 [4].
v Its strong dipole and high dielectric constant enable water to dissolve
large quantities of charged compounds such as salts [5].
2.2 Types of Water Resources
The type of a water resource is usually an indication of its water quality characteristics. The aquatic environments comprises of water in the soil or underground water, surface water and water in the atmosphere [7].
2.2.1 Underground water
Underground water is an aqueous solution in the subsurface [8].
Underground water supplies drinking water to over half the population of the
United States and provides an even greater percentage of the amount of water used for irrigation and industrial purposes [9]. Water present below the land 8 surface takes on some of the characteristics of that environment. Rainfall and snowmelt percolating through the soil zone and unsaturated materials chemically react with the gases, minerals and organic compounds that occur naturally in the subsurface. These reactions continue below the water table as the water flows through the aquifer. Of the many solutes found in underground water only a relatively few are present at concentrations greater than 1 mg/L under typical natural conditions. These are generally called the major ions, and they consist of the cations calcium (Ca2+), magnesium (Mg2+), sodium (Na+),
+ - 2- and potassium (K ), and the anions bicarbonate/carbonate (HCO3 /CO3 ),
2- - - sulphate (SO4 ), chloride (Cl ), and nitrate (NO3 ). An important non-ionic constituent in typical underground water is silicon (Si) [8].
Borehole is a well drilled into the sub-surface aquifer (aquifer is a porous and permeable rock hosting water or a water saturated geologic unit or formation that may be exploited for water for economic use) for the purpose of exploiting underground water. It is solely drilled to provide water for drinking, domestic and industrial uses [10].
2.2.2 Surface water
The use of surface water by man is as old as the existence of human beings, since water, which is a natural resource, is indispensable to life [11].
Surface water resources consist of the following:
i. Springs 9
ii. Rivers/streams
iii. Lakes and reservoirs
iv. Oceans/seas
Springs
A spring is a point in the hydrological cycle where underground water meets the land surface and flows into a stream [7]. The water quality at the surfacing point is usually excellent as the water has percolated through thick strata of soil. In this process of percolation, the water picks dissolved minerals
(such as calcium, magnesium, iron etc) and is purified of biological pathogens,
(disease producing organisms) such as bilharzias [12]. Though spring water is considered to be aesthetically acceptable for domestic use, presence of poorly designed pit latrines, poor wastewater management, poor solid waste management as well as poor and inadequate spring protection may lead to contamination of water from the springs with pathogenic bacteria [13].
Rivers
Rivers are surface streams. The quality of river water depends on the quality of the feeding sources which include surface run off, water glaciers, swamp rain and underground water, treated sewage, industrial effluents and population around the areas [11]. The most common causes of pollution in 10 rivers are pathogens (bacteria), siltation (the smothering of river and stream sediment, usually from soil erosion) and oxygen depleting substances.
The three leading sources of pollution in U.S Rivers were agriculture, hydrologic modifications and habitat modifications. Agriculture was the leading source of pollution, responsible for about 48% of the reported water problems in impaired rivers and streams. Hydrologic modifications were responsible for 20% of the impaired miles of rivers. These modifications include such things as flow regulation and the construction of dams. Habitat modifications are all those changes to habitat that directly affect water flow.
This includes removal of woody debris and land-clearing practices. The modification of river habitats can have a similar and equally destabilizing effect to aquatic life [14].
Lakes and Reservoirs
Lakes and surface water reservoirs are the planet’s most important freshwater resources and provide innumerable benefits. They are a source of water for domestic use, irrigation and renewable energy in the form of hydro- power and are essential resources for industry. Lakes provide ecosystems for fish, thereby functioning as a source of essential protein, and for significant elements of the world’s biological diversity. They have important social and economic benefits as a result of tourism and recreation, and are culturally and 11 aesthetically important for people throughout the world. They also play an equally important role in flood control [14].
The flood control achieved as a result of the construction of the
Kainji/Jebba dam has led to intensification in agricultural practices, including irrigation agriculture and fishing, in the regions around the Kainji and Jebba lakes and in areas downstream of the dam. Resulting from this is the increased use of fertilizers, pesticides and herbicides. Run-off from agricultural lands and refuse from residences located along the shores of the lakes are directly or indirectly discharged into the lakes [15]. Lakes can become polluted without obvious signs [16] and, as such, environmental monitoring as a means of detecting insidious pollution becomes very pertinent [15].
Oceans
Countless freshwater streams and rivers empty into the oceans [17]. The total dissolved solids content of sea water averages about 35000 ppm [18]. This includes 55% chloride, 30.6% sodium, 7.7% sulphate, 3.7% magnesium, 1.2% calcium, 1.1% potassium, 0.4% bicarbonate, 0.2% bromide and a number of others such as borate, strontium, and fluoride. Ocean salinity varies from place to place and sometimes from season to season. Regions of oceans that receive freshwater from large rivers or much rainfall are less salty than average. So, too, is seawater near melting polar ice, which is frozen freshwater. Conversely, when ice forms, nearby seawater becomes more saline. Overall, though, ocean 12 salinity is very stable. Seawater also has a relatively stable pH. The pH of seawater ranges between 7.4 and 8.3, which is slightly alkaline. Much of the carbondioxide that humans are adding to the atmosphere ends up in the oceans, where it reacts with water to form carbonic acid and so human activity is slowly acidifying the oceans [17].
2.2.3 Water in the atmosphere
Atmospheric water sources include all forms of precipitation such as snow, sleet, rainfall, drizzle, dew, boar, frost, fog, drip, ice pallets and granular snow. In rural environments where atmospheric pollution is not a major problem, rainwater provides an appropriate high quality source of water. Rain water is typically collected from roof tops and stored in tanks or cisterns. But because the roof or any collection surface is subject to contamination from nesting and flying birds and air borne dust, no one should assume that this source of water is the most suitable for human consumption [14].
2.3 Pollution
Pollution is defined as the release of toxic or harmful substances into the environment in quantities that are harmful to man, animals and plants. These harmful substances are called pollutants. It is the contamination of the earth’s environment with materials that interfere with human health, the quality of life or the natural functioning of ecosystems. Moreover, it must be present in an 13 amount sufficient to produce an unwanted effect. Although some environmental pollution is as a result of natural causes, most pollution is caused by human activities [19].
2.3.1 Water pollution
Water pollution is a big problem in the present day world. It threatens aquatic life and changes water bodies into unsightly, foul-smelling scenes. It also affects our health because of the harmful substances that accumulate in aquatic animals, one of our main sources of food. The main cause of water pollution is the indiscriminate dumping of solid and liquid wastes into water bodies [20]. The public health significance of water quality cannot be overemphasized. Many infectious diseases are transmitted by water through the fecal-oral route. Diseases contacted through drinking water kill about 5 million children annually and make 1/6th of the world population sick [21].
A large number of water pollutants may be broadly classified as: - Organic pollutants - Inorganic pollutants - Sediments pollutants - Radioactive materials - Thermal pollutants
2.3.1.1 Organic Pollutants
This group includes oxygen demanding wastes, disease carrying agents, plant nutrients, sewage, synthetic organic compounds and oil. Dissolved 14
Oxygen (DO) is an essential requirement of aquatic life. The optimum dissolved oxygen in natural water is 4-6 ppm. Decrease in this dissolved oxygen value is an index of pollution mainly due to organic matter, e.g sewage
(domestic and animal), industrial waters from food-processing plants, paper mills and tanneries, waters from slaughter houses and meat packing centers, run-off from agricultural lands, etc [1]. Organic pollutants can further be classified thus:
1. Refuse and sewage: It is a common practice to dump refuse and human
wastes into the river for easy disposal. The waste or sewage is mostly
organic matter. It is broken down into simple substances by
decomposers, mainly bacteria. In the process, the bacteria use up the
dissolved oxygen. Too much sewage in a water body causes an increase
in the bacterial population. This reduces the level of oxygen in the water.
If the oxygen level falls too much, the aquatic organisms start to die and
eventually the water body becomes clogged up and foul-smelling water
polluted by sewage contains many disease causing organisms [20].
2. Industrial wastes: Many factories empty their chemical wastes directly
into rivers and seas without converting them into harmless substances
first. These chemicals include fuels, plastics, plasticizers, fibers,
elastomers, organic solvents, detergents, paints, insecticides, food 15
additives and pharmaceuticals. Their presence in water imparts
objectionable and offensive taste, colour and odour [20].
3. Agricultural wastes: These include pesticides, insecticides, rodenticides,
molluscides, herbicide and fungicides. The negative aspect of these is
that their residues have moved through ecosystems and are threatening to
destroy the food chain [1].
4. Crude oil spills: Accidents and carelessness in oil rigs and tankers cause
crude oil spills mainly in the coastal waters. The oil floats on water and
kills most of the marine life in the affected areas. The oil then becomes
washed up on the beach, temporarily preventing people from using the
water and the beach for recreation [20].
2.3.1.2 Inorganic pollutants
These include the heavy metals. Advancement in technology has led to high levels of industrialization leading to the discharge of effluents containing heavy metals into our environment. Between 1850 and 1990, the production of these metals increased nearly by 10-fold with emissions rising in tandem [22].
Pollution by heavy metals can be classified into pollution on land, water and air
[23].
On the land, mining is the principal area where heavy metal pollution readily occurs. The indiscriminate dumping of scraps of old vehicles and 16 metallic materials litter the whole environment causing incalculable environmental pollution. Being aware that some heavy metals are naturally present in some natural water sources were some of them are essential for healthy living of organisms, there is pollution of streams and rivers through agricultural chemicals that flow into them and industrial metal waste effluents which are discharged into the bodies of water. This raises the concentration of the metals to intolerable limits making them toxic to aquatic life [23].
Heavy metals occur in air mainly as solid particulate matters. Metal particulate matters are all extremely diverse and complex, existing in the metallic or compound forms [23]. Heavy metals may also occur naturally as a result of normal geological phenomena such as formation of dunes, weathering of rocks and leaching [24].
2.3.1.3 Sediments pollutants
The natural process of soil erosion gives rise to sediments in water. It represents the most extensive pollutants of surface water. Bottom sediments are important sources of inorganic and organic metals in streams [1].
2.3.1.4 Radioactive materials
Four human activities are responsible for radioactive pollution;
- Mining and processing of ores to produce usable radioactive
substances
- Radioactive material in nuclear weapons 17
- Radioactive material in nuclear power plants
- Radioactive isotopes in medicine, industry and research
Exposure of high levels of radiation adversely affects human health. It is decidedly connected with the incidence of leukemia and other forms of cancer [1].
2.3.1.5 Thermal pollutants
Several industries like oil refineries, steel mills and breweries use water for cooling coal fired or nuclear fuel fired steam power plants. Usually water from a nearby river or lake is pumped in and used for the cooling process. The resulting warm water is then emptied back into the river or lake. This causes an increase in the temperature of the water. As a result, less oxygen dissolves in it leading to a decrease in dissolved oxygen of water and this affects aquatic life [20].
2.3.2 Underground water pollution/pollutant
An underground water pollutant is any substance that, when it reaches an aquifer, makes the water unclean or otherwise unsuitable for a particular purpose [25]. Various processes, some of which may be manmade or anthropogenic, generate pollutants and contaminants that enter underground water flow systems. These processes include physicochemical weathering, mass wasting, erosion, sediment transport and deposition, agricultural activities/mining, mine-waste disposal and acid mine drainage problems, oil exploration, exploitation, and gas flaring, sewage treatment, disposal, and management, runoff, floods, and snowmelt, biological pollution of wetlands 18 and impounded reservoirs, saline lakes, ponds, and evaporite deposits, geothermal springs and mineralized waters, atmospheric fallout and rainout, burial grounds, garbage dumps, landfills, etc . Some pollution sources in rural environments that are usually ignored, even though they may be hazardous, include pit latrines, open space communal toilets, wide scale and indiscriminate uses of the bush for defecation etc . Various environmental problems can arise as a result of underground water pollution. A major consequence of underground water pollution includes the potential contamination of surface waters. This can happen if the rivers, streams, or lakes in the areas are recharged by a polluted aquifer. The converse becomes the case if contaminated surface water recharges an aquifer. Some high-level wastes have pollutants and contaminants with long half lives. Because of this property, they remain hazardous for long times within the hydrogeologic environment and are very difficult to remove. Salmonellosis, bacillary, dysentery, schistosomiasis, helminthiasis, and viral infections are known to have been transmitted through drinking underground waters polluted by surface waters and sewage [2].
Cases of guinea worm infestation in parts of Ilorin and Abakaliki have continually been linked to the drinking of underground waters contaminated by heavily polluted surface waters. It is obvious that if systematically investigated, most outbreaks of waterborne diseases could be linked to pollution of underground waters from surface waters, septic tanks, pit latrines, and compost 19 heaps. In the Kano area, the filamentous iron bacteria leptothrix and crenothrix were found abundantly in nearly all the boreholes in the Bompal area, on the outskirts of Kano municipality. The industrialized world has accumulated great amounts of pollutants and contaminants within their environments [2].
Underground water pollution caused by human activities usually falls into one of two categories; point-source pollution and non-point source pollution [25].
2.3.2.1 Point-source pollution
Point-source pollution refers to contamination originating from a single tank, disposal site, or facility [25]. The pollutants or contaminants come from zones or areas of known and definable boundaries that are easily amenable to mathematical analysis and modeling. The pollution loads can be controlled at the point of input before they can spread into the surrounding environment in a time-discrete or continuous manner. Point sources include sewage lagoons, industrial wastes, landfills/garbage dumps, liquid/gaseous spills (oil, chemicals etc), mining, saline lakes and deposits, evaporite sequences etc [2].
2.3.2.2 Non-point source pollution
Non-point source pollution are those in which the pollutants or contaminants are spread through a large area of hydrogeologic environment and in which they extend over the entire source area. A distributed source is very widespread, and the pollutants may be introduced from various sources and 20 directions. Spreading is enhanced by wind, rain, and snowfall activities, through atmspheric circulation and precipitation [2]. The areal extent or boundary conditions for the pollutants are difficult to define because of the regional nature of sources, thereby posing problems for mathematical analysis.
The sources include acid-alkaline rain, floods, erosion, agricultural fertilizer applications, and generated agricultural wastes, sea sprays and intrusions, volcanoes etc. Acid rain is a major distributed source of pollution in developed countries such as the United States, Canada, Germany, etc [2]. Localized pollution of underground water by acid rain in some developing countries such as Nigeria has been reported [26]. In urban, sub-urban, and rural areas of many developing countries, particularly in the tropics, soil and gully erosion produce heavy sediment loads carried by floods that pollute surface water and underground water systems [27-29].
Because non-point source substances are used over large areas, they collectively can have a larger impact on the general quality of water in an aquifer than do point sources, particularly when these chemicals are used in areas that overlie aquifers that are vulnerable to pollution [25].
Sometimes the substance is a manufactured chemical, but just as often it might be microbial contamination. Contamination also can occur from naturally occurring mineral and metallic deposits in rock and soil. Hence underground 21 water pollution can further be classified into chemical pollution, biological pollution and physical/natural pollution [25].
2.3.2.3 Chemical pollution
One of the best known classes of underground water contaminants includes petroleum-based fuels such as gasoline and diesel. Gasoline consists of a mixture of various hydrocarbons that evaporate easily, dissolve to some extent in water, and often are toxic. Benzene, a common component of gasoline is considered to cause cancer in humans . Aquifers in industrialized areas are at significant risk of being contaminated by chemicals and petroleum products.
Another common class of underground water contaminants includes chemicals known as chlorinated solvents. As a general rule, the chlorine present in chlorinated solvents makes this class of compounds more toxic than fuels.
Unlike petroleum-based fuels, solvents are usually heavier than water, and thus tend to sink to the bottoms of aquifers. This makes solvent-contaminated aquifers much more difficult to clean up than those contaminated by fuels [25].
The use of pesticides, herbicides, fertilizers, and other materials to increase agricultural yields have some great negative effects on underground water quality. Pesticides and herbicides applied to fields or orchards may find their way into underground water when rain or irrigation water leaches the dissolved constituents downward into the soil. Nitrate from its fertilizer, one of the most widely used agricultural fertilizers, is harmful in drinking waters even 22 in relatively small quantities. The nitrate is very soluble and although some may be used by plants, much of the dissolved nitrate escapes unused into deeper parts of the soil and into underground water [30]. Nitrate is toxic to humans even in amounts as small as 10 to 15 ppm. Uranium and fluorine in phosphate fertilizers and probably rubidium in potash fertilizer are soluble under most conditions and will eventually find their way into the underground water regimes. The uses of lime for the production of fertilizer may result in lead and zinc contamination, if the lime is produced from metal-containing limestone [2].
2.3.2.3 Biological Pollution
Biological pollutants of underground water include dissolved organic constituents and microorganisms that seep or leach into underground water from polluted surface waters. The microorganisms may be either pathogenic or unpathogenic.
- Pathogenic microorganisms
These are present in underground water, especially in the vicinity of facilities that are discharging sewage effluents or contaminated surface waters.
Shallow wells and some deep boreholes are prone to contamination by these pathogens. The majority of waterborne pathogenic microorganisms enter water supplies as a result of faecal contamination. Pathogenic microorganisms normally associated with water supplies includes Enteamoeba histolytica, 23
Adenoviruses, Parvoviruses, Reoviruses, Salmonella typhis etc [2].pathogenic microorganisms can cause water borne diseases such as typhoid, cholera, and amoebic dysentery [31].
- Non-pathogenic microorganisms
Many nonpathogenic bacteria are as important as the pathogenic ones in the pollution of surface water and underground water supplies. These include the sulphur and iron bacteria. Among the sulphur bacteria are the sulphate reducers such as Desulfovibrio, Desulfomonas, and Desulfotomaculatum which produce elemental sulphur from sulphates. On the other hand, some of the sulphur bacteria oxidize elemental sulphur to sulphates, all of which involve complex oxidation-reduction reactions. These include the ubiquitous
Chemolithotrophic Thiobacillus and the filamentous gliding bacteria Beggiatoa and Achromatium. Iron bacteria are frequently present in underground water.
They obtain energy for their metabolism by the oxidation of ferrous and/or manganous ions .
In both cases, pathogenic and unpathogenic microorganism produce undesirable effects in the underground water itself and in the distribution network (where water may be distributed for domestic uses) and the populations using it [2].
24
2.3.2.5 Physical/natural pollution
For many years, people believed that the soil and sediment layers deposited above an aquifer acted as a natural filter that kept many unnatural pollutants from the surface from infiltrating down to underground water. By the
1970s, however, it became widely understood that those soil layers often did not adequately protect aquifers. Despite this realization, a significant amount of contamination already has been released to the nation’s soil and underground water. The toxic metal arsenic, for instance, is commonly found in the sediments or rock of the western United States, and can be present in underground water at concentrations that exceed safe levels for drinking water.
Radon gas is a radioactive product of the decay of naturally occurring uranium in the Earth’s crust. Underground water entering a house through a home water-supply system might release radon indoors where it could be breathed
[25].
Geologic rock units may be fractured, faulted, and jointed through tectonic movements or may be layered during the deposition and consolidation of sediments. Weathering disaggregates rocks into soils and sediments that are transported away by wind, water, and/or man. During these processes of the geologic cycle, pollutants and contaminants may be formed or released [2].
25
2.4 Water Analysis
The examination of water consists of the following:
- Physical examination.
- Chemical examination
- Microbiological examination
2.4.1 Physical examination
The following parameters are considered under physical examination:
2.4.1.1 Temperature
This influences the amount of dissolved oxygen in water which in turn influences the survival of aquatic organisms (raising the temperature of a freshwater stream from 20 to 300C will decrease the dissolved oxygen saturation level from about 9.2 ppm to 7.6 ppm) . Increasing temperature also increases the rate of chemical reactions taking place in the water. Increases in temperature are often associated with hot water discharge from power stations and industries that use water as a coolant [31].
2.4.1.2 Turbidity
Turbidity is a measure of water clarity [31]. It can also be defined as the cloudiness or haziness of a fluid caused by individual particles (suspended solids) that are generally invisible to the naked eye similar to smoke in air.
Fluids can contain suspended solid matter consisting of particles of many 26 different sizes. While some suspended materials will be large enough and heavy enough to settle rapidly to the bottom of the container if a liquid sample is left to stand, very small particles will settle only very slowly or not at all if the sample is regularly agitated or the particles are colloidal. These small solid particles cause the liquid to appear turbid. Turbidity in open water may be caused by growth of phytoplankton. Human activities that disturb land, such as construction, can lead to high sediment levels entering water bodies during rainstorms, due to storm water run-off, and create turbid conditions [32].
Urbanized areas contribute large amounts of turbidity to nearby waters, through storm water, pollution from paved surfaces such as roads, bridges and parking lots [33]. Certain industries such as quarrying, mining and coal recovery can generate very high levels of turbidity from colloidal rock particles.
In drinking water, the higher the turbidity level, the higher the risk that people may develop gastro-intestinal diseases. This is especially problematic for immune-compromised people, because contaminants like viruses or bacteria can become attached to the suspended solid. The suspended solids interfere with water disinfection with chlorine because the particles act as shields for the virus and bacteria. Similarly, suspended solids can protect bacteria from ultraviolet sterilization of water. In water bodies such as lakes and reservoirs, high turbidity levels can reduce the amount of light reaching lower depths, which can inhibit growth of submerged aquatic plants and 27 consequently affect species which are dependent on them, such as fish and shellfish [32].
2.4.1.3 pH
This measures the acidity or alkalinity of water. pH of rain water is about 5.5-6.0. Typically, natural water has pH of 6.5-8.5. Pure water has a neutral pH of 7, which is neither acidic nor basic. For aquatic life the pH should be between 6.0 and 9.0. A pH< 5 (acidic water) is most damaging to eggs and larvae of aquatic organisms. Most aquatic life (except for some bacteria and algae) cannot survive pH<4 [31]. One of the most significant environmental impacts of pH is the effect that it has on the solubility and thus the bioavailability of other substances. Runoff from agricultural, domestic, and industrial areas may contain iron, lead, chromium, ammonia, mercury or other elements. The pH of the water affects the toxicity of these substances. As the pH falls (solution becomes more acidic), many insoluble substances become more soluble and thus available for absorption [30].
2.4.1.4 Total dissolved solids (TDS)
This is the quantitative measure of the sum total of organic and inorganic solutes in water [22]. It is also defined as a conductivity test of available ions in
2+ + + 2+ 3+ - the water including Ca , Na , K , Fe , Fe , HCO3 and ions containing phosphorus, sulphur and nitrogen. High levels of sodium is associated with excessive salinity and is found in many minerals. Potassium is incorporated 28 into plant materials and is released into water systems when plant matter is decayed or burnt [31].
2.4.1.5 Conductivity
Conductivity, K, is a measure of the ability of an aqueous solution to carry an electric current. This ability depends on the presence of ions, on their total concentration, mobility and valency, and on the temperature of measurement. Solutions of most inorganic compounds are relatively good conductors. Conversely, molecules or organic compounds that do not dissociate in aqueous solution conduct a current very poorly, if at all [34]. Conductivity varies with temperature. It is usually measured at 250C [35].
2.4.1.6 Colour
This may result from natural minerals such as iron and manganese or coloured wastes discharged from industries. The colour produced by 1 mg/L of platinum in combination with ½ mg/L of metallic cobalt is taken as one standard colour unit [36].
2.4.2 Chemical examination
The following parameters are considered under chemical examination.
2.4.2.1 Hardness
This is defined as the sum of the calcium and magnesium ion concentrations [37]. Although other ions in water, such as iron and manganese, 29 can cause hardness, these are present in very small concentrations and are not, therefore, of any real significance to the water’s hardness. Calcium and magnesium can be present in water in the form of different salts, commonly as bicarbonates, carbonates, sulphates, and chlorides. On boiling, calcium and magnesium bicarbonates decompose to their carbonates which have a low solubility in water. Therefore, most of the hardness caused by calcium and magnesium present as bicarbonates or carbonates can be removed by boiling.
Hardness due to carbonate and bicarbonate salts is known as temporary hardness, since it is mainly removed by boiling. Temporary hardness is alternatively called carbonate hardness. Other salts of calcium and magnesium, such as sulphates and chlorides, are unaffected by boiling. Hardness caused by salts which are unaffected by boiling is known as permanent hardness [18].
Hard water has a noticeable taste, produces precipitates with soaps which inhibits lathering and forms precipitates (scale) in boilers, hot water systems and kettles according to the equation below:
2+ + 2C17H35COONa + Ca (C17H35COO)2Ca + 2Na [38] (scum) Studies on water hardness and cardiovascular disease mortality have suggested a lower incidence of heart disease in communities drinking hard water. Extremely hard water (hardness > 500 mg/L) is also unfit for consumption because the constituent minerals such as calcium can deposit inside the body if present in high amounts leading to kidney or gall bladder 30 stones. Consumption of water lacking in essential minerals like calcium, magnesium and other trace minerals is also harmful for the body because water low in mineral content would rob off the body’s minerals. People drinking such treated water excrete huge amounts of calcium, magnesium and trace minerals in urine. The more the mineral loss, the greater the risk for osteoporosis, osteoarthritis, hypothyroidism, coronary artery disease, high blood pressure and a long list of degenerative disease generally associated with premature aging
[39].
2.4.2.2 Alkalinity
This is defined as the acid-neutralizing capability of water. It is reported
- 2- - as due to HCO3 , CO3 , and OH , although borates, phosphates, ammonia, amines, silicates, organic carboxylates, phenates, and other basic anions may contribute [35]. Alkalinity is increased by caustic substances from industries
(KOH, NaOH), Soil additives in agriculture such as lime Ca(OH)2, superphosphate which is a mixture of Ca(H2PO4)2 and CaSO4, and soaps and detergents[31].
2.4.2.3 Calcium
A silver-white, chemically active, metallic chemical element, found always in combination in limestone, marble and chalk. One of the alkaline earth elements, fifth in abundance in the earth’s crust (3%), reacts with water and is an essential constituent of bones and teeth [35]. 31
Calcium ions are a major contributor to water hardness and are due to water running through rocks containing minerals such as gypsum
(CaSO4.2H2O), Calcite (CaCO3) and dolomite (CaMg(CO3)2) [31].
2.4.2.4 Magnesium
Magnesium is a light, silver-white, malleable, ductile, metallic chemical element. It is the eighth most abundant element in the earth’s crust. It is never found as a free element. It constitutes a large deposit as magnesite and the common rock forming dolomite. It is a nutritional element in animal and plant life. Magnesium has been considered as nontoxic to humans at the concentration expected in water (150 mg/L) [35].
2.4.2.5 Chloride
Chloride in the form of chloride ion (Cl-), is one of the major inorganic anions in water and wastewater. The salty taste produced by chloride ion concentration is variable and dependent on the chemical composition of water.
The chloride ion concentration is higher in wastewater than in raw water because sodium chloride is a common article of diet and passes unchanged through the digestive system. High chloride content may harm metallic pipes and structures, as well as growing plants [34].
2.4.2.6 Nitrate
Nitrate is a salt or ester of nitric acid or an end-product of the aerobic stabilization of organic nitrogen. Sources of nitrates are mineral deposits 32
(sodium and potassium nitrate), soils, seawater, and atmosphere. Nitrate is used as a fertilizer, as food preservative and as an oxidizing agent in the chemical industry. Lakes and reservoirs usually have less than 2 mg/L of nitrate measured as nitrogen. Higher levels of nitrates are found in underground water ranging up to 20 mg/L, but much higher values are detected in shallow aquifers, polluted by housing (sewage) and/or excessive use of fertilizers [35].
Nitrate is a problem as a contaminant in drinking water due to its harmful biological effects. High concentrations have been cited as a risk factor in developing gastric and intestinal cancer [40].
2.4.2.7 Phosphate
Mainly a salt of phosphoric acid, phosphate in nature is found in phosphate rock, in the mineral known as apatite, a tri-calcium phosphate. It is an important source of phosphorus. Also, it is the inorganic component of bones and teeth. The large demand for chemical fertilizers, worldwide has increased the production of phosphates. Phosphates are also used for production of special glasses, chinaware, baking powder, and detergents [35].
Total phosphate is used as an indicator of pollution from run-off in agricultural areas or domestic sewage. Concentrations of 0.2 mg/L are common.
Concentrations of 0.05 mg/L indicate the possibility of eutrophication
(increased nutrient concentrations) and algal blooms are likely [31].
33
2.4.2.8 Potassium
A soft, light, silver-white, waxlike, metallic, common chemical element of the alkali group. Potassium is the seventh most abundant element and constitutes 2.4% by weight of the earth’s crust. It is never found free in nature.
Most potassium minerals are insoluble. It decomposes in water, generating hydrogen and catching fire spontaneously . Extensively used in fertilizers, in glass, and in a limited way in the chemical industry, potassium is definitely an essential nutritional element for humans, animals, and plants. It is nontoxic but acts as a cathartic in excessive concentration (1-2 g). Acute toxicity may be reached in adults with a dosage of 7-10 g/day [35].
2.4.2.9 Sulphate
A salt or ester of sulphuric acid derived from elemental sulphur. It is a pale yellow, odorless, brittle, nonmetallic solid which is insoluble in water.
Indicated as SO4-ion, sulphates are found in natural waters in the final oxidized stage of sulphides, sulphites, and thio-sulphates. In all cases sulphate is found as a product of pollution sources related to mining or industrial wastes. High levels of sulphate causes diarrhea and dehydration [40].
2.4.2.10 Sodium
A soft, silver-white, extremely active, alkaline element, found in nature only in combined form, the sixth most abundant element on earth. Sodium compounds are used in paper, glass, soap, textile, petroleum, chemical and 34 metal industries. Sodium is a natural constituent of raw waters, but its concentration is increased by pollutional sources, such as rock salt treatment of road surfaces in below freezing temperature, precipitation run-off, and soapy solutions and detergents. Sodium is considered harmful in drinking water at high concentrations to persons suffering from cardiac, renal, and circulatory diseases [35].
2.4.2.11 Cadmium
Cadmium is a naturally occurring metal with an atomic number of 48, relative atomic mass of 112.10 gmol-1 and density of 8.65 gcm-3. In nature cadmium appears in zinc, copper, and lead ores. It is also found in low concentration in rocks, coal and petroleum. It is found in underground water more than in surface water as a natural occurrence. Therefore, it may enter the water supply from mining, industrial operations, and leachates from landfill
Also, cadmium may enter the distribution system from corrosion of galvanized pipes [35].
Cadmium is primarily a respiratory poison and has lethal potential than most other metals with mortality rate of 15% in poisoning cases. In humans, mild intoxication causes smarting of the eyes, dryness and irritation of the throat, tightness in the chest, and headache. With increased exposure, the respiratory distress increases with uncontrollable cough and gastrointestinal pain, nausea, vomiting and diarrhea [41]. 35
2.4.2.12 Chromium
Chromium occurs in nature in several chemical form and valence states.
It has an atomic number of 24, atomic mass of 51.996 gmol-1 and density of 7.1 gcm-3. It is found in the earth’s crust from 10-200 ppm. Chromium is a naturally occurring metal in drinking water. Chrome plating and chrome metallurgical and chemical operations may contaminate the atmosphere with chromium. In addition to fossil fuel combustion, solid waste incineration, and cement plant emulsion, other chromium salt usage is found in the leather industry, paints, dyes, explosives, ceramics, and papers, leading to industrial pollution [35]. Chromium when in excess in humans results in a chronic renal insufficiency in the kidney which is a disease in which the kidney no longer function properly but do not yet require dialysis. It is difficult to diagnose, as symptoms are not usually apparent until kidney disease has progressed significantly. Common symptoms includes a frequent need to urinate and swelling as well as possible anemia, fatigue, weakness, headache and loss of appetite. As the disease progress, other symptoms such as nausea, vomiting, bad breath and itchy skin may develop as toxic metabolites. Chromium often accumulates in aquatic life adding to the dangers of eating fish that may have been exposed to high levels of chromium [41].
36
2.4.2.13 Copper
Copper is a metallic element with an atomic number of 29, relative atomic mass of 63.5 g/mol and a density of 8.95 g/cm3. Copper is very commonly found on the earth’s crust as sulphides, oxides and rarely as metal.
Consequently it is found in surface water generally at concentrations below 20
μg/L. It may be detected in higher values from the consumer’s faucet as a product of corrosion of brass and copper pipes . As an algicide in surface water, it may vary seasonably in surface supplies. Copper in the air can be the product of copper dust, coal burning, and probably tobacco smoke. In food it is found in organ meats, shell fish, nuts, dried legumes, cocoa. Copper is considered an essential element for human nutrition since it is required in many enzymatic reactions. Poisoning from copper in water is normally avoidable because taste threshold concentration of copper is at 1.0-2.0 mg/L, levels at 5-8 mg/L make the water undrinkable, but poisoning occurs at higher concentrations. The daily requirement has been estimated at 2 mg/L [35].
Inhaled copper dust can produce eye and respiratory tract irritation, headache, vertigo (dizziness), discolouration of the skin and hair in humans.
Prolonged inhalation of copper fumes can result in pulmonary fibrosis, liver impairment and liver disease. Copper also appears to affect reproduction and development in human and animals. Sperm motility also appears to be compromised by the presence of copper in human spermatozoa [42]. 37
Individuals with Wilson’s disease (disorder of copper metabolism) are at additional risk from the toxic effects of copper [35].
2.4.2.14 Iron
Iron is a metallic chemical element with mass number of 26, atomic weight of 55.85 g/mol and density of 7.87 g/cm-3. In surface water supplies, the presence of iron is almost exclusively due to corrosion of pipes (the most commonly used material for water piping) and storage tanks. In underground water supplies, in addition to corrosion problems of the distribution system, high content of iron can be encountered due to the frequency of the elevated iron level in the earth strata related to the feeding aquifers [35]. In underground waters when a significant amount of carbondioxide and lack of oxygen is encountered, ferrous carbonate is dissolved as follows:
++ - FeCO3 + CO2+ H2O Fe + 2HCO3 [35]
It is a known fact that iron in trace amounts is essential for nutrition. The daily requirement is 1-2 mg with dietary ranges of 7-35 mg/day. Well water containing soluble iron may remain clear while pumped out, but exposure to air will cause precipitation of iron due to oxidation, with a consequence of rusty colour and turbidity. The presence of iron bacteria may clog well screens or develop in the distribution system [35].
38
2.4.2.15 Lead
Lead is a bluish-gray metallic element with atomic number of 82, relative atomic mass of 207.19 g/mol and a density of 11.3 g/cm3.
Concentration of lead in natural waters has been reported as much as 0.4-0.8 mg/L (mountain limestone and galena deposits encountered). Surface and ground raw waters range from traces to 0.04 mg/L [35]. Depending on one’s location on the face of the planet, the food and water supply as well as the air we breathe exposes us to lead. Lead exposure can also come from fumes released by automobiles, from fumes released during production in the heavy chemical industries and from mining of coal and other chemicals. Lead is the most significant toxin of the heavy metals [43].
In humans exposure to lead can result in a wide range of biological effects depending on the level and duration of exposure. Various effects occur over a broad range of doses, with the developing foetus and infants being more sensitive than the adult. It causes nausea, vomiting and other gastrointestinal effects in adults, but more serious impacts of central nervous system dysfunction and intelligence quotient (IQ) deficits occur in children. High level of exposure may result in acute and chronic lead toxicity [43].
2.4.2.16 Nickel
Nickel is a metallic element with atomic number 28, atomic weight of
58.69 g/mol and density of 8.90 g/cm3. Nickel is found in common metal 39 products such as jewelry. Food stuffs naturally contain severely high quantities.
It is released into the air by power plants and trash incinerators. Short-term exposure to nickel in humans is not known to cause any health problem but long term exposure can cause decreased body weight, heart and liver damage, and skin irritation [35].
2.4.2.17 Zinc
Zinc is a bluish-white, metallic element with atomic number 30, atomic weight of 65.38 g/mol and density of 7.13 g/cm3. Trace amounts (<0.05 mg/L) of zinc is present in most natural waters. Zinc may be present in higher levels in irrigation areas due to the use of galvanized iron, copper and brass in plumbing fixtures and for water storage [31]. A higher concentration of zinc (5-30 mg/L) is aesthetically objectionable in drinking water due to a milky appearance and a greasy film in boiling [35]. A concentration of zinc higher than 5 mg/L causes a bitter astringent taste and opalescence in alkaline waters [44]. Zinc, if associated with lead and cadmium, may indicate deterioration of galvanized iron and dezinfication of brass pipes [35].
2.4.3 Microbiological examination
Many protozoa, bacteria, viruses, algae and fungi are found in natural water systems. Some are pathogenic (typhoid, cholera and amoebic dysentery can result from water-borne pathogens) . The excessive growth of algae (called algal bloom) can degrade water quality because it lowers dissolved oxygen 40 levels thereby killing other living things. The level of bacterial contamination of water due to animal waste is measured by determining the number of coliform organisms such as E.coli [31]. Coliform organisms include
Escherichia coli, citrobacter, klebsiella, and Enterobacter spp. They are gram negative, oxidase-negative, nonspore forming rods that can grow aerobically in a medium containing bile salts. They are able to ferment lactose within
48hours, producing acid and gas at 370C [35].
The pollution of underground water by microorganisms could lead to problems such as depletion of dissolved oxygen, reduction of nitrate to nitrite or ammonia, reduction of sulphate to sulphide with attendant offensive odors and growth of filamentous bacteria, reaction of sulphide with iron to form an insoluble precipitate that can restrict underground water flow, and mobilization of iron from soil under conditions of reduced oxygen tension only to be oxidized and precipitated in other regions of the aquifer either by chemical or microbiological means [2]. 41
CHAPTER THREE
3.0 Materials and Methods
Table 3.1: Sample code and sample location
Sample code Sample location 1 Amechi Idodo 2 Mbulu Owo 3 Umueze 4 Agbani 5 Ugbawka 6 Isiogbo Nara 7 Akpugo 8 Amurri 9 Nara Unateze 10 Amodu Awkunanaw
3.1 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 42
FIG: 3.1 MAP OF NKANU EAST AND NKANU WEST SHOWING THE LOCATION OF BOREHOLES STUDIED 43
(BDH England), then rinsed severally with de-ionized distilled water, and finally with the water sample. The labeled cans were corked immediately and put into ice before transportation to the laboratory.
3.2 Method of Analysis
3.2.1 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.
3.2.2 Temperature
This was measured at the sampling point. JENWAY 470 conductivity meter model was used for this purpose.
3.2.3 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.
3.2.4 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 44 cell. The sample cell was taken to the conductivity meter and the value obtained was recorded.
3.2.5 pH
HANNA HI 4212 model pH meter was used for the determination of pH.
20 mL water sample was measured into a 25 mL sample cell . The sample cell was taken to the pH meter and the reading taken.
3.2.6 Conductivity
JENWAY 470 model conductivity meter was used. 20 mL water sample was measured into a 25 mL sample cell . The cell was taken to the conductivity meter and the reading was taken.
3.2.7 Total Alkalinity
Preparation of reagent
- 0.01 M H2SO4: 0.05 M H2SO4 was prepared by diluting 2.8 mL
concentrated H2SO4 to 1 liter. 0.01 M H2SO4 was now prepared by
diluting 200 mL of 0.05 M H2SO4 to 1 litre with distilled water [34].
Procedure
Potentiometric titration method was used for the determination of alkalinity [34]. The water sample was properly shaken and 100 mL of sample was measured into a 500 mL beaker. 0.01 M H2SO4 was titrated against the solution to a pH of 4.5. The volume of acid used was recorded.
45
Calculation
A x N x 50000 Total Alkalinity, mg CaCO3/L = ml sample
Where A average volume of acid used
N Normality of acid
mL sample volume of water sample used
3.2.8 Total Hardness
Preparation of reagent
- Buffer solution (pH 10): 57 mL of concentrated NH4OH was added to
6.75g NH4Cl. The resulting solution was dissolved and diluted to 100 mL
with distilled water [34].
- Eriochrome black T: 0.5 g of Erio T powder was added to 4.5 g of
hydroxylamine hydrochloride and dissolved in 100 mL of 95% ethyl
alcohol.
- 0.01 M EDTA: 3.723 g of the disodium salt was dissolved in 1 liter of
distilled water [34].
Procedure
Complexometric titration method was used for the determination of hardness [34]. 50 mL of the water sample was measured into a conical flask and 1 mL buffer solution (pH) was added followed by addition of 2 drops of
Erio T indicator. 0.01 M EDTA was titrated against the solution until the last 46 reddish tinge disappeared leaving a blue colour at the end point. The volume of
EDTA used was recorded.
Calculation
A x B x 1000 Hardness (EDTA) as mg/L CaCO3 = ml sample
Where A average volume of 0.01M EDTA used
B mg CaCO3 equivalent to 1.00 mL EDTA titrant or titre value mL sample volume of water sample used .
3.2.9 Calcium
Preparation of reagents
- I N sodium hydroxide: 4 g of NaOH was dissolved and diluted to 100 mL
with distilled water [34].
- 0.01 M EDTA: 3.723 g of the disodium salt was dissolved in 1 liter of
distilled water [34].
Procedure
Calcium was analysed using complexometric titration [34]. The water sample was thoroughly shaken and 50 mL of the sample was measured into a conical flask. 2 mL of sodium hydroxide was added, followed by addition of
0.1 g murexide indicator. 0.01M EDTA was titrated against the solution until the colour changed from pink to purple. The titre value was noted.
47
Calculation
A x B x 1000 Calcium hardness (mg/L) = ml sample
Where A Average volume of EDTA used
B mg CaCO3 equivalent to 1.00mL EDTA (titre)
at the calcium indicator endpoint
mL sample volume of water sample used.
3.2.10 Magnesium
Since hardness in water is mostly due to the presence of calcium and magnesium ions, magnesium hardness was determined thus:
Magnesium hardness (mg/L) = (Total hardness – calcium hardness) mg/L
3.2.11 Chloride
Preparation of reagent
- K2CrO4 indicator: 50 g K2CrO4 was dissolved in a little distilled water.
Silver nitrate solution was added until a definite red precipitate was formed.
The solution was allowed to stand for 12 h, filtered and diluted to 1 liter with distilled water [34].
- Standard AgNO3 (0.0141 N): 2.395 g of AgNO3 was dissolved in distilled water and diluted to 1000 mL with distilled water [34].
48
Procedure
Argentometric method was used for chloride determination [34].100 mL of filtered water sample was measured into a conical flask. 1 N sodium hydroxide was used to bring the pH to the range of 7-10 followed by addition of 1 mL K2CrO4 indicator. 0.0141 N AgNO3 was titrated against the solution to a pinkish yellow endpoint.
Calculation
(A − B ) x N x 35450 Chloride content (mg/L) = ml sample
Where A Average volume of AgNO3 used for sample
B Average volume of AgNO3 used for blank
N normality of AgNO3
mL sample volume of water sample used.
3.2.12 Nitrate
Procedure
This was done using the cadmium reduction method [34]. 50 mL beakers were filled with 25 cm3 of the water sample and one sachet of Nitraver 5
Nitrate powdered pillow was added. This was swirled to dissolve and then poured into a 10 mL sample cell and taken to the DR/890 HACH model colourimeter for a reaction time of one minute. When the timer beeped at the expiration of the one minute, the shift and the timer button was pressed again 49 for a 5 minutes reaction period. Then the absorbance was measured at a wavelength of 500 nm.
3.2.13 Sulphate Preparation of reagent Conditioning reagent: 50 mL glycerol was mixed with a solution of 30 mL concentrated HCl, 300 mL doubly deionised water, 100 mL 95% ethyl alcohol and 75 g NaCl [34].
Procedure Sulphate was determined using turbidimetry method [34]. 100 mL of sample was measured followed by the addition of exactly 5.0 mL conditioning reagent. The solution was mixed thoroughly using magnetic stirrer and stirring bar. As the stirring continued, 0.2 g of BaCl2 crystals were added and the solution was stirred for I minute at constant speed. After one minute, the sample was placed in a 5 cm cuvette and the absorbance was measured at 420 nm after exactly 4 min.
3.2.14 Phosphate
Preparation of reagent
- Armstrong reagent: 122 mL concentrated tetraoxosulphate (vi) acid
was added to 800 mL of water. This was followed by addition of 10.5 g
ammonium molybdate and 0.3 g antimony potassium tartarate [35].
- Ascorbic acid: 3 g of ascorbic acid was dissolved in 100 mL of distilled
water [35]. 50
Procedure
Ascorbic acid method was used for the determination of phosphate [35].
The glassware to be used was rinsed once with 1+1 HCl and severally with doubly deionised water. 50 mL of filtered sample was measured into the thoroughly cleaned glassware. 5 mL of Armstrong reagent was added followed by the addition of 1mL of ascorbic acid. The solution was swirled to mix properly. A 20 minute reaction period was allowed after which the sample was measured into a 5 cm cell and the absorbance taken against that of doubly deionised water at a wavelength of 880 nm.
3.2.15 Sodium
Procedure
SHERWOOD Flame photometer 410 model was used for the determination of sodium.10 mL of water sample was measured into a 10 mL sample cell. The sample was nebulized into the flame and the emission intensity was recorded.
3.2.16 Potassium
Procedure
SHERWOOD Flame photometer 410 model was used for the determination of potassium. 10 mL of water sample was measured into a 10 mL sample cell. The sample was nebulized into the flame and the emission intensity was recorded. 51
3.2.17 Heavy Metals Determination
Procedure
200 mL of water sample was measured into a conical flask. 10 mL of concentrated nitric acid was added followed by digestion of the solution until the volume reduced to below 25 mL. The solution was made up to 25 mL with distilled water in a volumetric flask. Atomic absorption spectrophotometer
(AAS) of the GBC Avanta ver 2.02 scientific model, was used for the heavy metals determination. It was first of all standardized using standard solutions and then the samples now in small sample cells were placed in the AAS. The metal concentrations in the water samples were measured and recorded. Lead, copper, zinc, cadmium, iron, nickel and chromium were determined using this procedure.
R Calculation: Heavy metals (mg/L) = C.F
R = AAS reading (Sample concentration - Blank concentration)
C.F = Concentration factor (8)
For zinc, 10 times dilution was made for samples from Amodu Awkunanaw and Amechi Idodo before determination. Therefore concentration of zinc in these water samples is given by:
D x R Zn (mg/L) = C.F
D = Dilution factor (10) 52
R = AAS reading
C.F = Concentration factor (8)
3.2.18 Bacteriological examination
Procedure
The bottle for sampling was sterilized for 15 minutes at 1210C in an autoclave. The samples were collected with spaces left for aeration and then kept in the oven on arrival to the laboratory. 100 mL of the sample was filtered through a cellulose based membrane which has a pore size of 0.45 μm enabling it to retain bacteria on the surface. After filtration the membrane was placed on a cellulose pad saturated with the growth medium. The plate was then incubated invertedly for a 24 hour period after which the number of colonies on the membrane was counted with the aid of colony counter microscope and the result was expressed as number of microorganism per 100 mL of water. 53
CHAPTER FOUR
4.0 Results and Discussion
Tables 4.1-4.6 give the concentrations of different parameters analyzed and the corresponding WHO guideline values.
Table 4.1: WHO guideline values for drinking water quality [45,46] Parameter Ingest desirable level Maximum permissible level Turbidity (NTU) - 5 Temperature (0C) - - Colour (Pt- Co) - 15 pH 7.0 -8.5 6.5-8.5 Conductivity (μs/cm) - 1660 Total hardness (mg/L) 100 500 Total dissolved solid - - (mg/L) Total alkalinity (mg/L) 500 1000 Nitrate (mg/L) 10 50 Sulphate (mg/L) 200 400 Phosphate (mg/L) 15.3 - Chloride (mg/L) 200 250 Sodium (mg/L) - 200 Potassium (mg/L) - - Calcium (mg/L) 75 200 2- 2- Magnesium (mg/L) 30 (if SO4 =250mg/L) 150 (if SO4 < 250mg/L) Lead (mg/L) - 0.01 Zinc (mg/L) 5.0 15 Cadmium (mg/L) - 0.003 Copper (mg/L) 0.05 1.6 Iron (mg/L) 0.1 1 Nickel (mg/L) - - Chromium (mg/L) - 0.05 Total coliform - 0/100mL (CFU/100mL)
54
Table 4.2: Physicochemical quality of Underground water in Nkanu East and Nkanu West Local Government Areas, Enugu State, Nigeria. S/N Sample location Amechi Mbulu Umueze Agbani Ugbawka Isiogbo Akpugo Amurri Nara Amodu Permissible Idodo Owo Nara unateze Awkunanaw level Parameter (WHO) 1 Temperature (0C) 27.5 27.3 26.7 27.1 27.3 27.3 26.6 27.7 27.5 27.1 - 2 Turbidity (NTU) 17.0 8.0 BDL BDL BDL 6.0 BDL BDL 3.0 98.0 5.0 3 Colour (Pt-Co) 143.0 47.0 0 0 0 21.0 0 0 35.0 550.0 15 4 Conductivity (μs/cm) 4360.0 4880.0 149.6 94.7 770.0 875.0 143.8 146.8 352.0 474.0 1660 5 Total hardness 289.0 73.0 2.5 30.0 31.0 15.0 53.0 41.0 31.0 211.0 500 (mg/L) 6 pH 7.8 8.2 7.5 6.4 8.1 8.0 6.4 6.5 7.4 7.1 6.5-8.5 7 Total dissolved solid 2650.0 2930.0 89.7 56.4 461.0 525.0 85.6 88.5 210.0 283.0 1000 (mg/L) 8 Total alkalinity 464.0 423.0 28.0 3.0 330.0 447.0 58.0 37.5 147.0 248.0 - (mg/L) 9 Nitrate (mg/L) 3.567 0.957 0.696 3.828 1.392 1.392 0.870 2.349 0.609 0.522 50 10 Sulphate (mg/L) 122.0 153.7 38.7 8.67 48.7 15.3 10.3 22.0 10.3 BDL 400 11 Phosphate (mg/L) 0.015 BDL 0.095 0.345 0.025 0.045 0.655 0.235 0.195 0.015 - 12 Chloride (mg/L) 15.50 56.98 22.49 8.75 4.75 18.49 0.25 6.50 6.50 1.50 250 13 Total coliform 70 55 0 0 0 0 0 0 0 0 0/100mL (CFU/100mL)
55
4.1 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
[35].
4.2 Colour
The values obtained ranges between 0-550.0 Pt-Co with water sample from Amodu Awkunanaw having the highest colour unit of 550.0 Pt – Co.
Unusually high intensity of colour at the source may be caused by the presence of iron and manganese, humus and peat materials. Colour is a physical 56 parameter that is not necessarily related to toxicity or pathogenic contamination of water. Nevertheless, harmful colour can create psychological rejection and fears, leading to limitation of water intake with consequent effects on personal health. There is a correlation between turbidity and colour values as shown in
Table 4.3 and Fig 4.1. This is because when turbidity is not removed, “apparent colour” is noted and it is possible that removing turbidity (filtration or centrifugation) may remove some “true colour” [35].
Table 4.3: Colour and turbidity of water samples
Sample Code 1 2 3 4 5 6 7 8 9 10
Colour (Pt- Co) 143.0 47.0 0 0 0 21.0 0 0 35.0 550.0
Turbidity (NTU) 17.0 8.0 0 0 0 6.0 0 0 3.0 98.0
Colour(Pt-Co) Turbidity(NTU)
500
400
300
200
100 Colour(Pt-Co) and Turbidity(NTU)
0 1 2 3 4 5 6 7 8 9 10 Sample code
Fig.4.1: Bar Chart showing Colour and Turbidity of water sample 57
4.3 Conductivity
This lies within the range of 94.7-4880.0 μs/cm with Amechi Idodo water sample and Mbulu Owo having the highest values of 4360 μs/cm and
4880 μs/cm respectively. These high values did not agree with the WHO standard of 1660 μs/cm [45]. Mbulu Owo water sample with the highest conductivity value also has the highest concentration of sodium. This is because conductance of water increases with salts [47].
4.4 Total Dissolved Solid
Total dissolved solid of the water samples ranges from 56.4-2930.0 mg/L with Mbulu Owo and Agbani water samples having the highest and lowest values of 2930.0 mg/L and 56.4 mg/L respectively. The water samples from Amechi Idodo and Mbulu Owo were found to possess high TDS value when compared with the WHO standard of 1000 mg/L [46]. This may be as a result of natural contact of water with rocks and soil [35] though of aesthetic rather than health hazards [48]. The higher the concentration of electrolytes in water the more is its electrical conductance. Total dissolved solids and conductivity can be used to delineate each other [50]. In this study, conductivity is proportional to the dissolved solids as shown in Table 4.4 and
Fig 4.2.
58
Table 4.4: Total dissolved solid and conductivity of water sample
Sample Code 1 2 3 4 5 6 7 8 9 10
TDS (mg/L) 2650 2930 89.7 56.4 461 525 85.6 88.5 210 283
Conductivity 4360 4880 149.6 94.7 770 875 143.8 146.8 352 474
(µs/cm)
Total dissolved solid(mg/L) Conductivity(us/cm) 5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0 1 2 3 4 5 6 7 8 9 10 Total dissolved solid (mg/L) and conductivity (us/cm) Sample code
Fig.4.2: Total dissolved solid and conductivity of water sample
4.5 pH
The pH ranges from 6.4-8.2. 80% (8 out of 10) of the samples had a pH
within the WHO recommended range of 6.5 to 8.5 [45]. Water samples from
Agbani and Akpugo have pH of 6.4 each. This could be attributed to the 59 contamination of water with acid from agricultural and domestic activities [49].
Samples collected from Umueze (7.5) and Nara Unateze (7.4) were slightly basic. Though pH has no effect on human health, all the biochemical reactions are sensitive to variation of pH. For most reactions as well as for human beings, pH value 7.0 is considered best and ideal [49].
4.6 Total hardness, calcium hardness and magnesium hardness
Hardness is one of the very important properties of underground water from utility point of view for different purposes [49]. The water samples in this study showed moderate hardness, ranging from 2.5-289.0 mg/L CaCO3. Water could be considered to be very hard if hardness exceeds the WHO maximum permissible level of 500 mg/L [46]. It is well known that hardness is not caused by a single substance but by a variety of dissolved polyvalent metallic ions, predominantly calcium and magnesium ions, although other ions like barium, iron, manganese, strontium and zinc also contribute [49].
Very hard water is not good for drinking and is associated with rheumatic pains and gouty condition. Such water does not lather with soap and produces deposits and scaling in pipes and steam boilers, hardens vegetables and would not allow it to cook well. When used for bathing it tends to harden the skin, or make the skin rough due to impregnation of insoluble calcium and magnesium soaps [50]. On the other hand soft water is associated with rickets in children and can cause corrosion. Very soft water has hardness of between 50 and 60 60
mg/L [24]. Moderately hard water as found in this study is considered to be
good dietetically [51].
The calcium level and magnesium level ranges between 2 -138.0 mg/L
and 0.5 -151.0 mg/L respectively. In the present study total hardness was
positively correlated with calcium and magnesium hardness as shown in Table
4.5 and Fig 4.3. Amechi Idodo and Umueze water samples had the highest and
lowest values for hardness (289.0, 2.5) mg/L, calcium hardness (138.0,2.0)
mg/L and magnesium hardness (151.0,0.5) mg/L respectively. This is as a
result of the significant effect of magnesium and calcium ions on hardness of
water [31].
Table 4.5: Total hardness, magnesium and calcium hardness of water samples.
Sample Code 1 2 3 4 5 6 7 8 9 10
Total hardness(mg/L) 289.0 73.0 2.5 30.0 31.0 15.0 53.0 41.0 31.0 211.0 Calcium hardness 138.0 44.0 2.0 17.0 18.0 4.0 46.0 36.0 14.0 126.0 (mg/L) Magnesium hardness 151.0 29.0 0.5 13.0 13.0 11.0 7.0 5.0 17.0 85.0 (mg/L)
61
Total hardness(mg/L) 300 Calcium hardness(mg/L) Magnesium hardness(mg/L)
250
200
150
100 and Magnesium hardness(mg/L) 50 Total hardness(mg/L), Calcium hardness(mg/L) 0 1 2 3 4 5 6 7 8 9 10 Sample code
Fig.4.3: Bar chart showing correlation between total hardness, calcium hardness and magnesium hardness. 4.7 Total Alkalinity The buffering capacity ranges from 3-464 mg/L with the sample from
Amechi Idodo having the highest value of 464 mg/L and Agbani water sample having the least value of 3 mg/L. The constituents of alkalinity in neutral system include mainly carbonate, bicarbonate and hydroxide components [49].
Alkalinity is not a significant parameter from the potability viewpoint [40] but it is a big problem in industries, as alkaline water if used in boilers for steam generation may lead to precipitation of sludge, deposition of scales and can cause caustic embrittlement [49].
4.8 Nitrate 62
The nitrate level ranges from 0.522 – 3.828 mg/L with the highest nitrate level of 3.828 mg/L recorded from Agbani water sample. 100% of the samples had nitrate levels within the WHO maximum permissible level of 50 mg/L
[46]. This may be an indication of little or no contamination from human wastes, nitrogenous fertilizer, or micro flora, which break down to release nitrate into water. For public drinking water supplies, a level of 10 mg/L nitrate has been established as the maximum allowable concentration, therefore nitrate concentration above the value of 10 mg/L is dangerous to pregnant women and poses a serious health threat to infants less than three to six months of age because of its ability to cause methemoglobinemia (blue baby syndrome) in which blood loses its ability to carry sufficient oxygen [52].
4.9 Phosphate
Phosphate values were very low, ranging from 0.015 – 0.655 mg/L and indicate that there was little or no seepage of domestic sewage or runoff water.
Water samples from Umueze, Agbani, Akpugo, Amurri, and Nara Unateze with concentrations of 0.05 mg/L and above indicate the possibility of eutrophication (increased nutrient concentrations) and algal blooms [31].
Phosphate was not detectable in Mbulu Owo water sample.
4.10 Sulphate 63
Sulphate levels ranging from 8.67 – 153.7 mg/L were obtained and these falls below the WHO permissible limit of 400 mg/L [45]. The comparatively high value in Mbulu Owo water sample may have contributed significantly to the elevated values of conductivity and TDS measured in the water samples from this sampling point. High levels of sulphate above 600 mg/L causes diarrhea and act as purgative in humans [53]. sulphate is one of the least toxic anions. The lethal dose for human as potassium or zinc sulphate is 45 g. The major physiological effects resulting from the ingestion of large quantities of sulphate are catharsis, dehydration and gastrointestinal irritation. Because of the gastrointestinal effects resulting from the ingestion of drinking water containing high sulphate levels, it is recommended that health authorities be notified of sources of drinking water that contain sulphate level in excess of
500 mg/L [54] .
4.11 Chloride
The chloride levels ranged from 0.25 – 56.98 mg/L. The values obtained were below the WHO maximum permissible level of 250 mg/L [46]. Mbulu
Owo and Akpugo had the highest and lowest chloride values of 56.98 and 0.25 mg/L respectively.
4.12 Sodium and Potassium 64
The data on metals in Table 4.6 shows that the concentrations of sodium and potassium were within the WHO standards for drinking water [46].
Sodium level ranges from 0.45 – 15.1 mg/L while that of potassium ranges from 1.75 – 18.0 mg/L. Sodium is very important for human body and regulates the water balance and the acid-base balance in the blood and tissue. Sodium in drinking water is not a health concern for most people because in healthy people, excess sodium is eliminated through the kidneys and the correct balance of sodium and water is maintained. But for people with heart disease, hypertension, kidney disease and circulatory illness, it may be an issue of health concern because of their inability to maintain the required body balance of sodium [55,39] . The Food and National Board of the National Research
Council of America recommends that sodium intake be limited to no more than
2400 mg per day [39].
The maximum and the lowest levels of sodium was determined in Mbulu owo and Akpugo water samples. All the samples analyzed contain much lower level of sodium than the maximum permissible limit of 200 mg/L suggested by
WHO. Sodium may affect the taste of drinking water at level above 200 mg/L
[54]. Most water supplies contain less than 20 mg of sodium per liter, but in some countries levels can exceed 250 mg/L [56] .
There is no fixed health guidelines for the amount of potassium present in water that would be considered safe by the WHO. Drinking water is not the 65 major dietary source of potassium, and the level in drinking water seldom reaches 10 mg/L. However, USEPA has set a maximum level of 100 mg/L. In people on low potassium diets, strokes, high blood pressure, and diabetes occur more frequently than in those who consume sufficient or high potassium diets
[54]. The potassium content of drinking water varies greatly depending on its source. It tends to be larger in mineral water than ordinary tap water. The
Committee on Dietary Allowances recommends 1875-5625 mg per day of potassium in order to maintain adequate and safe levels of potassium balance
[39]. Waters with potassium exceeding 2 mg/L is not suitable for regular drinking because it may cause kidney stress and possible kidney failure [57]. 66
Table 4.6: Metal concentrations (mg/L) of borehole water samples from Nkanu East and Nkanu West LGAs Enugu state, Nigeria . S/N Parameter K Na Ca Mg Pb Zn Cd Cu Fe Ni Cr
Sample location 1 Amechi Idodo 8.61 8.41 138. 151.0 0.008 0.48 0.016 0.015 1.05 <0.05 0.066 0 2 Mbulu Owo 6.45 15.1 44.0 29.0 0.007 0.017 0.01 0.029 0.59 <0.05 0.079 3 Umueze 1.75 4.68 2.0 0.5 <0.004 0.07 <0.002 0.01 0.16 <0.05 <0.002 4 Agbani 12.8 1.16 17.0 13.0 <0.004 0.017 <0.002 0.008 0.03 <0.05 0.004 5 Ugbawka 5.38 4.28 18.0 13.0 <0.004 0.05 0.004 0.013 1.17 <0.05 <0.002 6 Isiogbo Nara 1.85 13.4 4.0 11.0 <0.004 0.009 <0.002 0.004 0.077 <0.05 0.01 7 Akpugo 2.83 0.45 54.0 3.0 <0.004 <0.006 <0.002 0.013 0.20 <0.05 <0.002 8 Amurri 18.0 0.55 36.0 5.0 <0.004 <0.006 <0.002 0.007 0.128 <0.05 <0.002 9 Nara unateze 2.44 4.58 14.0 17.0 <0.004 0.01 0.004 0.025 1.39 <0.05 <0.002 10 Amodu 6.35 3.47 126. 85.0 <0.004 0.85 0.004 0.002 1.93 <0.05 <0.002 Awkunanaw 0 mean 6.65 5.60 33.3 44.05 0.007 0.188 0.008 0.013 0.67 - 0.04 0 ± ± ± ± ± - ± - ± ± - - SD 5.29 5.15 35.9 79.64 - 0.31 - 0.009 0.67 - - 6 WHO STD - 200 200 150 0.01 15.0 0.01 1.6 1.0 - 0.05 DL - - - - 0.004 0.006 0.002 0.001 0.003 0.05 0.002
DL = Detection limit SD = Standard Deviation 67
4.13 Heavy Metals
The level of copper and zinc obtained ranges between 0.002 -0.029 mg/L and 0.009 – 0.85 mg/L respectively which are within the WHO permissible limit [45]. Copper on the other hand is not a cumulative systemic poison. Doses up to 100 mg taken by mouth causes symptoms of gastroenteritis with nausea [35]. Copper levels in drinking water vary widely as a result of variations in water characteristics such as pH, hardness and copper availability in the distribution system [58].
Only two samples from Amechi Idodo and Mbulu Owo showed values above the detection limit for lead. The values are within the WHO guideline values of 0.01 mg/L [45]. A major source of environmental lead, particularly in urban areas is the combustion of leaded petrol. Lead then enters the waterways from soil, thus affecting the levels of lead in natural waters [59]. Lead is present in tap water to some extent as a result of its dissolution from natural sources but primarily from household plumbing systems in which the pipe, solder, fittings, or service connections to homes contain lead [60].
Cadmium level ranges between 0.004-0.016 mg/L with the sample from Amechi Idodo having value above the WHO guideline value of 0.01 mg/L [45]. The cadmium level in unpolluted waters is usually below 0.001 mg/L [61]. 68
Iron concentrations in the study ranged between 0.03 – 1.93 mg/L with
40% of the samples having values above the WHO permissible limit of 1 mg/L
[46]. Amechi Idodo, Ugbawka, Nara Unateze and Amodu Awkunanaw water samples had values of 1.05 mg/L, 1.17 mg/L, 1.39 mg/L and 1.93 mg/L respectively. Amodu Awkunanaw water sample with the highest value for iron
(1.93 mg/L) also has the highest colour unit (550.0 mg/L). This shows that iron has a significant effect on colour of water [35]. The high levels of iron detected in these samples may be as a result of corrosion problems of the distribution system, frequency of the elevated iron level in the earth strata related to the feeding aquifers and leaching of iron salts (acid mine drainage) [40]. It is a known fact that iron in trace amounts is essential for nutrition. The brownish precipitate or sediments found in underground water is mostly due to oxidation
2+ 3+ of Fe and Fe in form of Fe(OH)3 which present unaesthetic appeal [49].
Chromium was detected in Amechi Idodo, Mbulu Owo, Agbani and
Isiogbo Nara water samples. The water samples from Mbulu Owo and Amechi
Idodo have values that are above the WHO permissible limit of 0.05 mg/L [45].
Trivalent chromium may be nutritionally essential with a safe and relatively innocuous level of 0.20 mg/day. Hexavalent chromium has a deleterious effect on the liver, kidney, and respiratory organs with hemorrhagic effects, dermatitis and ulceration of the skin for chronic and subchronic exposure [40]. 69
All the values obtained for nickel were below detection limit. Nickel has low toxicity comparable to zinc, manganese, and chromium. It does not accumulate in tissues [35].
4.14 Total Coliform
The samples from Amechi Idodo and Mbulu Owo with total counts of
70 and 55 respectively exceeded the WHO standard of zero Cfu/100 mL [45].
This may be due to contamination from improper construction, shallowness, animal wastes, proximity to toilet, sewage and seepage from refuse dump sites
[62].
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: 70
- 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.
71
REFERENCES
1. Chatterjea, M.N, & Shinde. R (2007): Textbook of Medical Biochemistry. 7th Edition, Jaypee Publishers, p 727-730.
2 Egboka B.C.E, Nwankwor. G.I, Orajaka. I.P. and Ejiofor. A.O.(1989): Principles and problems of Environmental pollution of Groundwater Resources with case Examples from Developing countries. Environmental Health Perspectives p 41-46,59-63.
3 Nkanu East-wikipedia, the free encyclopedia , http://en.wikipedia.org/wiki/Nkanu-East D.L. 2009-10-20.
4 Nelson, D.L., Cox. M.M (2008): LEHNINGER Principles of Biochemistry. Fifth edition, p 43,65-66.
5 Murray, R.K., Bender. D.A, Botham K.M., Kennelly. P.J., Rodwell. V.W., Weil. P.A. (2009): Harper’s Illustrated Biochemistry. International Edition, McGraw Hill. p 6, 8.
6 Skoog, D.A, West. D.M, Holler. F.J, Crouch. S.R, (2004): Fundamentals of analytical chemistry, eighth edition. p 231.
7 Chukwu, K.E. (1999): “Water supply systems and environmental health”, workshop on environment, sanitation and human existence, UNTH, Enugu, 4th-5th August, p. 16-21.
8 Deutsch, W.J. (1997): Groundwater Geochemistry fundamentals and applications to contamination p 2, 5 and 7.
9 Davis, B.E (1990): Heavy metals in soils p 177-196.
10 Leopold, L .B(1977): Encyclopedia of Science and Technology, Mcgraw-Hill, New York, p 337-339.
11 Freeze, A.R. and Chemy. A.J. (1979): Groundwater, prentice Hall Inc, Eaglewood Cliffs, p. 45-50.
12 Obasikene, J.I., Adinna, E.N. and Uzoechi, I.F.A. (eds) (2000): Man and the Environment, Computer Edge publishers, Enugu, p.115-117.
72
13 Haruna, R., Ejobi. F., Kabagambe. E.K. (2005): The quality of water from protected springs in Katwe and Kisenyi parishes, Kampala city, Uganda, African Health Sciences vol. 5 No.1 p14.
14 Surface water: Rivers and lakes-water quality of the Nation’s Rivers and streams http://www.Libraryindex.com/pages/2585/surface-water-Rivers- Lakes-WATER-QUALITY, 04-08-2008.
15 Oyewale, A.O., Musa.I. (2006): Pollution assessment of the lower basin of lakes Kainji/Jebba, Nigeria: heavy metal status of the waters, sediments and fishes. Environmental Geochemistry and Health 28: 273- 281.
16 Biney, C, Amuzu. A.T., Calamari. D, Kaba. N, Mbome. I.L, Naeve. H., Ochumba. P.B., Osibanjo. O, Radegonde. V, Saad. M. A (1994): Review of heavy metals in the African aquatic environment. Ecotoxicol Environ safe 28, 134-159.
17 Awake (2006): why is the sea salty? July 2006, Issue of Awake. p 16 &18.
18 Lorch, W. (1987): Water quality classification in Handbook of water purification, 2nd Ed, Lorch W. (Ed), Harwood Ellis Ltd: Chichester, p 90-92, 84.
19 Robert, L.R (1997): Man and the Environmental information Guide series, Gale Research company, Michigan, vol. 7, p 36.
20 Ababio, O.Y (1990): New School chemistry. Africana Fep publishers. p 259-260.
21 WHO (2004). Water Sanitation and Health Programme. Managing water in the home: accelerated health gains from improved water sources. World Health Organization. www.who.int .
22 Colin, B (1999); Environmental chemistry, 2nd Edition, W.H. Freeman and company. p 4.
23 Acres, G.K (1993): Catalyst systems for emission control from motor vehicles, 3rd edition smith and Hill, U.S.A p 221. 73
24 Warren, L.J (1981): “contamination of sediments of lead, cadmium and zinc”. Review, Environmental Pollution (series B), p2, 401-436.
25 Groundwater Pollution, www.waterencyclopedia.com. 10/07/2009.
26 Uma, K.O (1986): Analysis of transmissivity and hydraulic conductivity values of sandy aquifers of the Imo River Basin, Nigeria. Ph. D Thesis, University of Nigeria, Nsukka, Nigeria.
27 Egboka, B.C.E, and Orajaka, I.P (1986): Models of soil and gully erosion dynamics, j. Water Resources (Iraq)5(1): 279-299.
28 Egboka, B.C.E. (1983): Analysis of groundwater resources of Nsukka area and environs, Anambra State, Nigeria. Nig. J.Min. Geol 1 and 2: 1- 16.
29 Egboka, B.C.E and Nwankwor, G.I. (1985): The hydrogeological and geotechnical parameters as agents for the expansion of Agulu Nanka gully, Anambra State, Nigeria. J. Afr. Earth Sci 3(4): 417-425.
30 Egboka, B.C.E (1984): Nitrate contamination of shallow groundwaters in Ontario, Canada .Sci Total Environ. 35: 63-65
31 Chemistry Tutorial: Water Analysis, http://www.ausetute.com.au/waterana.html 8th August 2011.
32 “pH and its effects on water quality”, http://www.kywater.org 11-06- 2009.
33 U.S. Environmental protection Agency. Washington, D.C. “National management measures to control Non-point source pollution from urban Areas”. Chapters 7 and 8. Document No. EPA 841-B-05-004. November 2005.
34 Eaton, A.D, Clesceri, S.L, Rice. W.E, Greenberg, A. E (2005): standard methods for the examination of water 21st edition p 15, 67.
35 Dezuane, J. (1997): Handbook of drinking water quality. 2nd Edition p 66-73,88,102-116, 121-126,130-132.
74
36 Welcher, F.J (1963): Standard methods of chemical analysis. volume 2. p. 409.
37 Smith, R.K (1999): Hand-book of Environmental Analysis. Genium publishing company, Canada, 4th ed p 237.
38 Baroni, .L, Cenci . L, Tettamntia. M and Berati . M(2007): Evaluating the environmental impact of various dietary patterns combined with different food production systems, European journal of clinical nutrition,61, 279-282.
39 Mahajan, R.K; Walia; T.P.S and Sumanjit, B.S.(2006). Analysis of physical and chemical parameters of bottled drinking water. Intern .J. Environ. Health.Res. 16:89-98.
40 Egereonu, U.U (2005): A study on the groundwater pollution by nitrates in the environ, Aba, Nigeria, J. chem. soc. Nigeria vol. 30 No.2. p 211- 212.
41 Voogt, D.P, Van. H.B, Feemstra, J.P, Copius-peerebom J.W (1980): Toxicological and environmental chemistry review p 89-109.
42 Wentz, C.A (1989): Harzadous waste management, McGraw Hill in U.S.A. p 88-95.
43 Us Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Diseases Registry (1993): Toxicological profile for mercury
44 APHA, AWWA, WPCF (1985): Standard methods, 16th edition, Washington, D.C: American public Health Association.
45 World Health organization (WHO) Guidelines for Drinking water quality, 3rd ed, Vol.1, Recommendation, Geneva, 2004 (cited Nov 19 2007), available from:http://www.indawater.portal. Org//tt/wq/res/GDWQ2004web:pdf .
46 WHO Guidelines for Drinking water Quality Recommendations, World Health Organization, 2nd Edition Geneva, 1993.
75
47 Okoye, C.O.B and Okpara, C.G (2010): Physicochemical studies and bacteriological assay of groundwater resources in Isikwuato local government area of Abia state , Nigeria. Journal of the chemical society of Nigeria. Vol 35 No.1 p 4.
48 EPA, (2002): US Environment Protection Agency, Safe Drinking Water Act Amendment http://www:epa.gov/safe water/mcl.Html. 10-05-02
49 Gupta, D.P, Sunita and Saharan, J.P (2009): Physicochemical analysis of groundwater of selected area of Kaithal city (Haryana) India. http://www.sciencepub.net.
50 Greenberg, E.A, Clesceri. L.S, Eaton. A.D (1992): Standard methods for the Examination of water and wastewater, 18th ed, APHA-AWWA- WEF: Washington, DC.
51 Escritt, L.B. (1972): Public Health Engineering I: water supply and Building sanitation, 4th ed. Macdonald and Evans Ltd: England. p 66.
52 Nduka, J.K, Orisakwe. O.E, Ezenweke. L.O. (2009): Nitrate and Nitrite levels of potable water supply in Warri, Nigeria: A public health concern, Journal of environmental health(Galley proof).
53 Obasi, R. A. and Balogun. O. (2001): Water quality and Environmental impact assessment of water resources in Nigeria, African Journal of Environmental studies, 2 (2), 228-231.
54 Saleh, .M.A; Ewane, E.; Jones, J. and Wilson, B.L.(2001).Chemical evaluation of commercial bottled drinking water from Egypt .J. Food Comp. Anal. 14: 127-152.
55 Lau, O.-W. and Luk, S.-F.(2002). A survey on the composition of mineral water and identification of natural water. Intern. J. Food Sci. Technol. 37: 309-317.
56. Codex Alimentarius (2001). The code of hygienic practice for the collecting, processing and marketing of natural mineral waters. CAC/RCP 33-2001,Codex Alimentarius vol.11: section 3.2.1.
57. Codex Alimentarius (1985). The code of hygienic practice for the collecting, processing and marketing of natural mineral waters 76
containing the provision on authorization of springs, wells and drillings. CAC/RCP 33-1985, Codex Alimentarius vol. 11: section 3.1
58 Nazif,W.; Perveen.S. and Shah,S.S (2006). Evaluation of irrigation water for heavy metals of Akbarpura Area ,j.Agric. Biol. Sci. 1 : 51-54.
59. Ministry of Health (2005). Draft Guidelines for Drinking-water Quality Management for New Zealand, 2nd ed. Ministry of Health ,Wellington.
60. Daskalova, B.N.(2007). A method for determination of toxic and heavy metals in suspended matter from natural waters by inductively coupled plasma atomic spectrometry (ICP-AES):part 1 Determination of toxic and heavy metals in surface river water samples .j. Univ. Chem. Technol. Metal 42: 419-426.
61. Dabeka, R.W; Conacher, H.B.S.; Lawrence, J.F.; Newsome W.H; Mckenzie, A.; Wagner, H.P.; Chadha, R.K.H. and pepper, k (2002). Survey of bottled drinking waters sold in Canada for chlorate, bromide, bromated, lead, cadmium and other trace elements. J. Food Addit. Contam. 19 :721-732.
62. Bitton, G (1994): Waste water Microbiology. Gainesville, New York Wiley –Liss. p 118.