Determination of Heavy Metals in Waters of Lower River Kuywa
Stephen Wekesa Muchanga
Department of Chemistry, Jomo Kenyatta University of Agriculture and Technology (J.K.U.A.T), P.O.Box 62,000-00200, Nairobi, Kenya.
Ali Mohammed Salim *
Department of Chemistry, Jomo Kenyatta University of Agriculture and Technology (J.K.U.A.T), P.O.Box 62,000-00200, Nairobi, Kenya.
*Author to whom correspondence should be addressed.
Abstract
Heavy metals are required by the biological organisms as nutrients but their availability above certain limits leads to adverse conditions such as bone, nerve and internal body organs damage like liver, high blood pressure, acute poisoning and death in animals and human beings and reduction of photosynthesis production, inhibition of seed germination and decreased crop yield in plants. River Kuywa being in a rich inorganic farming of sugarcane and maize area as well as industrial and urban environment, it is exposed to pollution. The objective was to determine the levels of heavy metal concentration using an Atomic absorption spectrometer and the effects of physicochemical parameters to the metal ions concentration which could arise from pollution. Temperature, pH, electrical conductivity and total dissolved solids were found to be (22.9, 23.3 C̊), (7.19, 4.34), (312.43, 318.45 µS) and (201, 204 mg/L) for upstream and downstream side of pollutants entry point respectively. Chromium, Copper and Zinc ions had relatively high concentrations compared to Cadmium ions. Lead ions were below the detection limit. Chromium, Copper and Zinc had (0.2660 ppm, 0.4276 ppm), (0.1306 ppm, 0.085 ppm) and (0.1369 ppm, 0.1395 ppm) while Cadmium had (0.0684 ppm, 0.0513 ppm) for upstream and downstream respectively. All physicochemical parameters were within WHO limits except pH. Chromium and Cadmium concentrations were above WHO limits while Copper and Zinc were below. Chromium had elevated concentration compared to other metals. There should be continuous and close monitoring of Chromium levels by reducing the factors leading to high rate of rock weathering and leaching. The water having Chromium and Cadmium concentrations above recommended limits, it should be treated first for Quality Assurance before it is consumed. Agencies like NEMA and WARMA should increase water quality surveillance operations for surface water.
Keywords: Heavy metals, quality assurance, WHO, effluents, physicochemical parameters.