Multivariate analyses of heavy metals in soils and Colophospermum mopane leaves around the Selebi Phikwe nickel-copper mine and smelter/concentrator plant area, Botswana

Abstract

This study was conducted in order to ascertain levels of concentrations and areal distribution of heavy metals in the surface soils and vegetation around the Selebi Phikwe Ni-Cu mine and smelter/concentrator plant, Botswana. One hundred and forty samples each of soil and Colophospermum mopane leaves obtained from ten sites, were analyzed by atomic absorption spectrometry (AAS) technique for their concentration levels of Cu, Ni, Fe, Cr, Co, Cd, Zn and Se. Data analysis was done mainly using the statistical package for social science (SPSS). Multivariate analysis was used to determine the distribution of metals within the study area. Concentration values obtained for analysed soil samples were as follows: Cd ranged from 0.01 to 0.05 ppm; Co from 1.0 to 28 ppm, Cr from 0.03 to 14 ppm; Cu from 11 to 116 ppm; Fe from 31 to 430 ppm; Ni from 19 to 120 ppm; Se from 0.01 to 0.03 ppm, and Zn from 17 to 68 ppm. The concentration values obtained for analysed mopane leaves were as follows: Cd was between 0.01 and 0.05 ppm, Co ranged from 1.0 to 28 ppm; Cr from 0.03 to 11 ppm; Cu from 4 to 116 ppm; Fe from 31 to 430 ppm; Ni from 19 to 120 ppm; Se was between 0.01 and 0.03 ppm, and Zn was between 17 and 79 ppm. In general heavy metals concentrations in both soils and vegetation depended on the site and proximity of the sampling locations to the mine. The findings of the study depicted that concentrations of heavy metals in soils and leaves of colophospermum mopane decreased with increase in distance from the mine and smelter/concentration plant.


Journal of Applied Sciences and Environmental Management Vol. 9(1) 2005: 177-185