Surface Water Quality Assessment around Chania Catchment in Kenya and Determination of Metal Concentrations by TXRF Technique

Surface waters are prone to pollution especially from agriculture and other anthropogenic activities hence the need to establish the levels of pollution. This present work focuses on Chania catchment situated on the lower side of the Aberdares water tower of Kenya that supplies 95 % of water to the capital Nairobi. The aim of this study was to determine the physico-chemical and microbial quality of surface water in the catchment and also establish the water quality after treatment during the wet and dry seasons. Water samples were randomly collected in triplicate from five strategic locations and analysed for heavy metals by Total-Reflection X-Ray Fluorescence (TXRF) Spectroscopy. Other water quality parameters tested include chloride, sodium, nitrates, phosphates, EC, pH, turbidity, TDS and Total Coliforms. The microbiological quality of the raw surface water was found to contain a high number microbial indicator counts implying that the water is not suitable for drinking without treatment. Generally, most of the physico-chemical parameters were within the allowable WHO recommended maximum contaminant levels (MCL) with the exception of wet season where water samples had values of turbidity higher than WHO guideline values. Results of heavy metal analysis revealed that surface water in some sampling points was polluted with Manganese, Iron, Nickel and Lead above WHO recommended levels with Thika River sampling point having higher levels of metal pollutants.