Heavy metals and cyanide distribution in the villages surrounding Buzwagi gold mine in Tanzania

Abstract

The study aimed at assessing the levels of heavy metals and cyanide in water and sediments in villages surrounding Buzwagi gold mine, both during wet and dry seasons.  A total of 56 samples of water (28 from each season) and 44 samples of sediments (22 from each season) were collected from the wells in the area and were analyzed for total cyanide and heavy metals.  The total cyanide was analyzed spectrophotometrically whilst the heavy metals were analyzed by an Inductively Coupled Plasma (ICP). The Pb and Fe levels in water were found to exceed 10 µg/L and 2000 µg/L respectively, the World Health Organization (WHO) limits for drinking water in some wells. It was therefore concluded that the water is not safe for drinking. The concentrations of cyanide and most of the heavy metals in sediments (except Cd and Hg which were below the detection limit) were higher in the wells closest to the Tailing Storage Facility (TSF) than the wells which are far from the TSF showing that the contamination to the water is due to mining activities. Furthermore concentrations of most of the parameters in sediments were higher in dry than in wet season. It was recommended that the water contamination should be prevented by having a regular inspection of the TSF liner so as to ensure zero discharge and that the alternative source of water should be provided to the mining communities.

Key Words: Heavy metals pollution, Total cyanide, ground water pollution and  mining.