Assessment of selected physico-chemical parameters of ground water in Tharaka Nithi County, Kenya
Kanyaru, Savina Mbura
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ABSTRACT Ground water contamination has become one of the main environmental issues and a challenge to the world population especially in arid and semi-arid areas. The levels of physico-chemical parameters of ground water exceeding the Kenya Bureau of Standards permissible guidelines have resulted to health problems among the water users especially in rural areas of developing countries, where a significant number of serious human health problems have been reported. Kenya being a water scarce country encourages ground water use as a way of availing clean water to all yet some of the ground water sources are said to contain some physico-chemical parameters above the permissible standards. The study sought to assess the selected physico-chemical parameters of ground water in Kamanyaki location, Tharaka Nithi County, Kenya with the following specific objectives; to determine the physico-chemical parameters of ground water during dry and wet season, to compare the levels of physico-chemical parameters of ground water during dry and wet season and to compare the levels of physico-chemical parameters of ground water with the Kenya Bureau of standards. Field survey design was used and it was accompanied by laboratory tests to analyze the level of each parameter from eight shallow wells. Plastic sample bottles of 1000ml were used to collect a total of 64 samples. In-situ measurements of temperature, electrical conductivity, total dissolved solids, dissolved oxygen, pH and turbidity were taken using mercury thermometer, conductivity/total dissolved solids meter, dissolved oxygen meter, pH meter and turbidimeter respectively. The water samples were stored at a temperature of below 100C in the cool box containing ice cubes for transportation to the Water Resources Management Authority laboratories in Nairobi where the analysis of the chemical parameters; fluoride, nitrates, phosphate, sodium, potassium, chloride, total hardness, magnesium, calcium ions and total alkalinity was done. The results were compared to Kenya Bureau of Standards in order to assess the suitability of the ground water for domestic use. The results reveal that the physico-chemical parameters during the dry season were significantly different (P≤ 0.05) from the wet season and the physico-chemical parameters during the dry and wet season were found to be significantly different (P≤ 0.05) from the recommended levels by the Kenya Bureau of Standards with the mean levels for fluoride being higher than the recommended standards in both seasons. The mean levels for fluoride during dry and wet season were found to be 5.0 mg/l and 2.9 mg/l respectively which were higher than the Kenya Bureau of Standards 1.5mg/l standards. Electrical conductivity was also found to be significantly different (P≤ 0.05) from Kenya Bureau of Standard which is 1400 μs/cm in the two seasons with the mean levels of 2836μs/cm and 3824μs/cm in dry and wet season respectively. Therefore there is need to supply clean water for domestic purposes in the study area as the ground water in the area is not safe for drinking especially due to the high levels of fluoride in the water which could have contributed to the dental discolouration among many residents in the area.