ASSESSMENT OF HEAVY METAL IMPACT ON MUKUVISI RIVER IN HARARE, ZIMBABWE

Abstract

This study examined the impact assessment of heavy metals in the Mukuvisi River, Harare Zimbabwe for the two of its major seasons, the summer and rainy season. Several studies have been done for the impact assessment but this study is the first of its kind in Harare Zimbabwe as it focuses on heavy metal that are discharged by industries along the Msasa industrial area into the river. The objective is to investigate and analyze the quantity of heavy metals that are discharged into the Mukuvisi river and carry out an impact assessment so as to come up with mitigation measures and solutions that will help the Zimbabwe National Water Authority (ZINWA) to make policies and enforcing strict laws to polluting industries so as to maintain the ecological health of the river. We also presented the difference in the heavy metal concentrations between the summer and rainy season while samples were collected according to the Standard Association of Zimbabwe (SAZS 560:1997) procedure using polythene bottles which were previously immersed in 10% nitric acid and scrubbed with deionized distilled water and samples taken to the laboratory for analysis. The water quality parameters analyzed were Arsenic, Mercury, Cadmium, Chromium, and Palladium. The mean level range of Arsenic, Mercury, Cadmium, Chromium, and Palladium was found 0.04, 0.065, 0.045, 0.01, and 0.01 mg/l, respectively, for the summer season, while for the rainy season, the concentrations were 0.04, 0.028, 0.028, 0.009 mg/l, and below 0.01 mg/l respectively for each sampling site. High heavy metal concentrations were recorded in summer, while low heavy metal concentrations were recorded in the rainy season which shows a clear seasonal effect between the two seasons as there were some variations.