Determination and speciation of heavy metals in sediments of the Hartbeespoort Dam by sequential chemical extraction

The speciation of 10 heavy metals Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn in Hartbeespoort Dam sediments was determined by applying a sequential extraction procedure. Environmental risks associated with the potential remobilisation probability of these metals were evaluated. The results showed that with regard to total metal content, the sediments of the Hartbeespoort Dam would compare with moderately to heavily polluted fluvial systems in Europe and North America. The observed metal distribution patterns in the different sediment fractions, however, indicated that major proportions of most metals seemed to be associated with the inert fraction and could therefore be classified to be of geochemical origin. This result is supported by the extraordinary metal-rich rock types of the Transvaal complex in the area surrounding the Hartbeespoort Dam