Geochemical assessment of heavy metals accumulation and fractionation in fluvial sediments of the Central Rand Goldfield, South Africa

摘要

University of the Witwatersrand, P. Bag X3, WITS 2050, Johannesburg, South Africa Mine tailings generate significant environmental impacts in the form of water and air pollution. Surface runoff from impoundments leads to deposition of sediments in water bodies. The Fleurhof Dam and Russel Stream in the Central Rand, South Africa are such cases where surface runoff led to an accumulation of sediments in the dam and along the stream bed, respectively. This study was aimed at the quantitative assessment of accumulation of heavy metals and acid mine drainage pollutants in the dam and stream due to surface runoff, deposition and siltation. Concentrations in sediments were found to be several orders of magnitude more than in the source tailings suggesting that the sediments, particularly in the organic-rich zones, trap these pollutants significantly. Leaching and sequential extraction protocols were used to characterise the compositional fractionation of heavy metals, particularly gold in the sediments.