Abstract:
Pollution of ground water sources continues to remain an area of great concern due to the fact that pollution places a restriction on water use hence leading to water scarcity; and at the same time places high treatment cost for users downstream. Pollutants such as nitrates and phosphates are known to cause eutrophication of rivers and lakes, algal bloom, blue baby syndrome in new borns and also produce unpleasant smell and taste in water due to bacterial growth. High levels of heavy metals in water lead to bioaccumulation via the food chain. Bioaccumulation of metals such as lead, chromium and manganese always lead to complications such as brain and spinal cord inflammation; liver and kidney damage, liver cirrhosis and bronchitis respectively. It is therefore crucial to determine the levels of both anions and heavy metals when determining water quality. The objective of the study was to assess the quality of water along River Sio, Busia County, Kenya. Water samples were collected in pre-washed polyethylene bottles and analyzed for both physical and chemical characteristics. The data was subjected to statistical analysis using Microsoft excel. Turbidity was the highest recorded physical parameter with a range of 12.03±0.61 NTU to 44.33±0.5 NTU during the dry season and 212.50±0.50 NTU to 481.83±0.76 NTU during the wet season. The pH of water was in the range of 7.45±0.02 to 7.62±0.02 during the dry season and 6.70±0.04 to 7.24±0.05 during the wet season. Temperature was in the range of 23.47±0.15 0C to 25.43±0.21 0C during the dry season and 24.03±0.12 0C to 27.20±0.10 0C during the wet season. In water, 53% of the parameters showed significant seasonal variation at the 95% level of significance, with the mean concentration of 56% of the parameters being higher during the wet season according to paired t-test. The parameters that exceeded the WHO limit were turbidity, phosphates, lead, iron, nickel, chromium and cobalt indicating poor quality of water in River Sio. In sediments lead, copper and nickel were the only cations that were above the WHO recommended limit while cadmium was below the limit of detection. According to geoaccumulation index, nickel showed moderate pollution during the dry season. The contamination factor for lead was very high during the dry season, while pollution load index confirmed pollution due to anthropogenic activities in sampling sites 1 – 4 during the dry season and no pollution due to anthropogenic activities during the wet season. Poor agricultural practices, domestic and industrial waste water are the main factors that contribute to pollution of water and sediments in River Sio. The study proposes proper land use, proper treatment and disposal of sewage and use of organic manure and biological control as means of preventing water and soil pollution.
