Studies on levels of mercury, znic and cadmium in some crops in the mining communities of Tarkwa, Prestea, Bankyim and Agona in the south western part of Ghana

Abstract

This research was conducted to detennine the levels of mercury, cadmium and zinc in the leaves of Xanthosoma sagittifoliwn (kotombre), Marlihot esclIlenta(cassava leaves) and the conn of Colecasia esclIlenta (taro conn) growing in the mining communities of Tarkwa, Prestea, Bankyim and Agona Junction. The Random sampling method was used to collect the samples and the wet digestion method was used to digest the samples for AAS analysis. A statistical analysis of the results of the research reveals that the concentrations of Hg, Zn and Cd in samples from mining communities were higher than samples from non mining communities and that there is a significant difference in the means at 95% confidence level. When the results obtained were compared with WHO and EPA permissible values, zinc and cadmium concentrations in the samples were within the nonnal concentration found in plant leaves and conns. The levels of mercury in the samples were however in the phytotoxic concentratio'n range. There is therefore a cause for concern regarding the levels of Hg, in the selected vegetable crops from the mining district ofTarkwa because heavy metals can bioaccumulate as they move up the food chain.