Analysis of Selected Heavy Metals in Water from River Kuywa and Adjacent Wells in Bungoma Central Sub County- Kenya

Industrial effluents, agricultural chemicals such as pesticides, herbicides and residential wastes are the major sources of heavy metals in drinking water. Presence of heavy metals in drinking water is the cause of many diseases in human beings. Worldwide over six million people lack access to clean drink water. In Kenya it has been reported that sources of drinking water such as rivers, boreholes and wells are having heavy metals. In Bungoma Central Sub County, residents depend on River Kuywa and well water for domestic consumption and agricultural activities. River Kuywa and adjacent wells are at risk of exposure to heavy metal by virtue of them passing through sections of factories and crossing several farms which intensively use agrochemicals and also through residential areas. The main objective was to determine levels heavy metals from both river water and well water and compared to the limits set by world Health Organization (WHO) and Kenya Bureau of Standards (KEBS). Sampling was done at various points along the river and from randomly selected wells adjacent to the river during the dry and rainy seasons. The levels of heavy metals were determined by use of FAAS, and data analysis was achieved by use of ANOVA and t-test. Results for two seasons ranges as follows; levels in mg/l in river water are Pb (0.57±0.09 - 3.36±1.15), Mn (0.15±0.14 - 0.25±0.03), Cu (1.01±0.12-1.92±0.14) and Cd (0.32±0.02-0.99±0.67). In well waters the ranges (mg/l) were Pb (1.43±0.34-2.43±0.41), Mn (0.15±0.14- 0.25±0.03) Cu (1.39±0.24-1.92±0.14) and Cd (0.35±0.03-0.46±0.03). From the results the mean values of Pb, Cu and Cd were above those set by KEBS and WHO and levels Manganese were below the set value. This was attributed to the surrounding industrial and agricultural activities, as well as domestic wastes. These results signify high levels of heavy metal in drinking water of the Sub County, and this pauses health risk to residents. Moreover, significant differences (p<0.05) were observed in the levels of heavy metals in water between the seasons (dry and wet). These findings call for urgent intervention by the government to set in place strategies that would reduce further contamination of water in river Kuywa and in wells in Bungoma County (author)