ABSTRACT

This study determined the quality of surface and underground water in Itagunmodi in Nigeria. Physicochemical analysis of water samples collected within gold mining area and the water consumed in the town was carried out to determine their hygienic conditions. The major objective of this study was assessment degree of groundwater pollution around the mining sites and the available water consumed in the town. Four major sources of water were analyzed. Several physical and chemical parameters were tested in groundwater, these include pH, total solids (TS), total dissolved solids (TDS), conductivity, total alkalinity, total hardness (TH), chloride (Cl^-1), sulphur (S), heavy metals (Pb, Zn, Cu), major cation (Mg). The results show that the parameters are within the standard acceptable levels which are required for drinking water adapted from World Health Organization. The pH of the samples was suitable for drinking according to the World Health Organization standard. For a safe drinking water, the pH should be between 6.5 and 8.5); it can be said that the water quality of the samples are fairly good based on the monitored elements and physicochemical characteristics.  

Key words:  Groundwater, conductivity, heavy metals, gold mining site, pollution.

Groundwater is water located beneath the ground surface in soil pore space and in the fractures of lithologic. It makes up about 20% of the world’s fresh water supply which is about 0.61% of the entire world’s water including oceans and permanent ice. Groundwater is naturally replenished by surface water from precipitation, streams and rivers when this recharge reaches the water table. Rain water dissolves soluble salts from vegetations, topsoil, river bed, lake bed into water bodies, hence most ions (Ca²⁺, Mg²⁺, Na⁺, K⁺ and NH₄⁺) in rain water are also found in surface and groundwater.

 

Groundwater is an important water resource in both the urban and rural areas of Nigeria but in the cities, pipe borne water is also available. Rural dwellers rely basically on hand-dug wells for potable water supply as the streams usually dry up in dry season. These resources are under threat from pollution either from human life style manifested by the low level of hygiene practiced in the developing nations (Punmia and Jain, 1998; Akujieze et al., 2003). Environmental health involves all the factors, circumstances and conditions in the environment or surroundings of humans that can influence health and well being. The neglect of rural areas in most developing countries in terms of basic infrastructures such as pipe-borne water and sanitation facilities, expose the villagers to a variety of health related problems such as water - borne diseases (Sridha, 2000).

 

Recent research conducted by Yisa and Jimoh (2010) showed that there was an increase in the demand for freshwater due to rapid growth of population as well as the accelerated pace of industrialization in the last few decades. Groundwater has long been considered as one of the purest forms of water available in nature and meets the overall demand for rural and semi-rural people (Tyagi et al., 2002). This was considered as the major source of water for human activities (consumption inclusive) especially in the rural area (Fasunwon et al., 2008).

Inadequate amounts of water for basic hygiene can contribute to poor hygiene practices, which in turn can lead to skin and eye diseases, and act as a key factor in the transmission of many diarrhoeal diseases (Ramakrishnaiah et al., 2009) reported that once ground water is contaminated, its quality cannot be restored. It therefore becomes imperative to protect it in other to prevent water borne diseases such as typhoid, cholera, diarrhoea and dysentery which are potentially communicable (Okeke and Igboanua, 2003; Suleiman, 2006).

Water from various sources contains varying forms of dissolved gases, minerals, organic and inorganic substances, chemical compounds and suspended matter such as organisms and dirt (Erah et al., 2002). Pure water is never found in nature, but contains impurities which vary from dissolved gases, chemical compounds to suspended matter such as organism and dirt especially in this part of the world (Sandhu et al., 1976). The most important physical characteristics are turbidity, colour, odour, taste, temperature and solids, while the chemical characteristics are acidity, alkalinity, hardness and corrosiveness (Ademoroti, 1996a). Water of good quality is necessary if it is to be acceptable by the people.

 

Palatability of water describes the characteristics of being pleasing to sense of taste. However, palatable water in real sense is not necessarily safe to drink or potable (Packham, 1996). Trace metals of different types can be found in water. Very low amount of trace metals are required by living things, but in excess concentration, metals can be harmful (Rand and Petriocelli, 1985). Potassium and sodium are very soluble salts and most of them leached from rocks, soils and plants tend to remain in solution. High concentration of potassium and sodium cause foaming in boiling water and have toxic effect on fish (Vermani, 1989).

 

Some water bodies may contain pathogens that are harmful in the body. The water sources in the area were either from bore-hole, streams or other sources, in which one may not be sure if analysis were carried out or not. Access to potable water is still a major concern in all the developing nation of the world as millions of people died of water-borne diseases annually.

In this study, the levels of some physical, chemical, water quality parameters in hand-dug wells, streams, borehole, deep well located in the residential areas and in the vicinities of Itagunmodi, a rural settlement in southwest Nigeria was carried out. In this work water from gold mining area was included in the analysis. Since gold is extremely resistant to weathering, when freed from enclosing rocks, is carried downstream as metallic particles consisting of "dust," flakes, grains, or nuggets.

 

Geology of the study area

 

Itagunmodi is located on latitude (DMS) 7031’60’’ longitude (DMS) 4039’0’’ and altitude (meters) 347 the time zone is east (est). The approximate population for 7 km radius from this point is 12655. Itagunmodi is a town very close to towns such as: Ile-Ife, Ilesa in Osun State, Nigeria. The sediment-hosted disseminated gold deposits (SHDGD) in Itagunmodi, Osun State, Nigeria is located in the clayey soil types derived from variably migmatised gneiss, biotite-and-biotite hornblende-gneiss and weathered amphibolites respectively (Figure 1).

 

 

Sample collection

 

The analyses were carried out between the months of February to July, 2013, and their average values were recorded in Table 1. The water sources include: (i) Deep well; (ii) Shallow well; (iii) stream, and (iv) Borehole. Samples were taken to the laboratory within two weeks. It was found out in the course of the work that most of the inhabitants get most of their domestic water from the well and drink directly without purification. The mean concentrations of the samples were calculated and used for the study.

 

Parameters analyzed

 

Physical and chemical parameters were analyzed in groundwater samples. The physical parameters include pH and electrical conductivity (EC). The chemical parameters include: Nitrite (NO₃), chloride (Cl), sulphate (SO₄), lead (Pb), iron (Fe), zinc (Zn), copper (Cu), biological oxygen demand (BOD), and groundwater, these include pH, total solids (TS), total dissolved solids (TDS), conductivity, total alkalinity, total hardness (TH), chloride (Cl^-1), sulphur (S), heavy metals (Pb, Zn, Cu), major cation (Mg).

 

Theory

 

 

Where   M = Molarity of EDTA used and V = volume of EDTA used.

Fe and Cr were measured with S series atomic absorption spectrophotometer (AAS) 

The pH values of the samples were shown in Table 1. The highest average value of 7.83 was measured in sample 2, and the lowest value of 6.5 was measured in sample 5, this was shown in Figure 1. The results obtained were within the standard range of 6.5 to 8.5 required for drinking water according to W.H.O and the Nigeria standard. This occurs in most natural waters. The lower the pH, the more corrosive the water will be. The pH of sample collected from the gold mining site is acidic while the other samples are alkaline. Those samples within the town of Itagunmodi are also regarded as safe drinking water; the average pH values lies between 6.5 and 7.4, these values lie between the permitted ranges in drinking water quality standard used in Nigeria.

 

 

Low values are most often caused by lack of carbonate minerals, such as calcium and magnesium found in limestone. Water leaking from a landfill may also lower pH. Other analysis such as conductivity, total dissolved solids, chlorine, copper and zinc, falls within the maximum permitted level with reference to Nigeria drinking water standard which are: 1000.00, 500.00 mg/L, 250.00 mg/L, 0.01 mg/L, 1.00 mg/L and 3.00 mg/L.

 

The total solids analyzed, the highest value was recorded in sample 3, and lowest in sample 5. It was high in sample 4 and the lowest was recorded in sample 5 while in total dissolved solids, the highest was recorded in sample 2 and the lowest was in sample 5, samples 3 and 4 were higher than that in sample 5. The conductivity was higher in sample 3 than in sample 4 while those of samples 1 and 2 were lower and sample 5 has the lowest value. The alkalinity was higher in sample 5, while those of samples1, 2, 3 and 4 were low. The concentration of CaCO₃ in samples 2 and 3 were higher than the value obtained sample 1 and 4 with the lowest value in sample 5. All the samples have higher concentration in Mg because they exceed the WHO standard for drinking.

 

The average concentration of chlorine was higher in sample 3 then sample 1, 5 and 4, with the lowest value in sample 2. Average sulphate concentration was highest in sample 5, high in sample 4 and low in samples: 1, 2 and 3. For Lead, sample1, 3, 4 has zero concentration and sample 2 and 3 concentrations exceed WHO standard. The average concentration of Cu was highest in sample 5 than in other sample. The average concentration of Zn was higher in sample 2 than in other samples, The maximum permitted level for magnesium in Nigeria is 0.20 mg/L, this value depend on consumer acceptability e.t.c., can be used to confirm the water samples as been hygienic for human consumption. This does not pose any significant water quality problem, because these results are within the standard acceptable levels of drinking water used in Nigeria. For Arsenic, all the samples are polluted with Arsenic because the arsenic concentrations exceed WHO standard. Arsenic can cause damage to the nervous system. Examples of diseases caused by arsenic are: Cancer of the lung, skin, prostate, kidney and liver, diabetes mellitus and hypertension. The WHO’s guideline value for arsenic in drinking water is 0.05 mg/L (given a provisional guideline value of 0.01 mg/L in 2006).

 

Phosphate in all the samples exceeds the WHO standard which means that water is polluted with phosphate in all the samples. In the sample Iron in sample 2 has the highest concentration, samples 3, 4, and 5 have higher concentration and sample 1 has the lowest concentration. Iron in all the samples is within WHO standard for drinking water. Although, iron is an important dietary requirement in humans needed by haemoglobin and good for several other functions, when high concentrations of iron are absorbed, iron is stored in the pancreas, the liver, the spleen and the heart. This may damage those vital organs. The presence of excess iron in water imparts the taste and it also promotes growth of iron bacteria that hasten rusting process of all the ferrous metals that come in contact with the water (Chukwu et al., 2008).

A FORTRAN program was also used to determine the present state of water sources in the town, the data for each set of parameters were insert into program at various stage and run. The results show that the samples were within the intake of the people.

 

 REFERENCES

 APPENDIX