ORIGINAL ARTICLE Modelling natural attenuation of heavy-metal groundwater contamination in the Selebi-Phikwe mining area, Botswana M. O. Schwartz Æ J. Kgomanyane Received: 29 January 2007 / Accepted: 29 May 2007 / Published online: 28 June 2007...
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ORIGINAL ARTICLE Modelling natural attenuation of heavy-metal groundwater contamination in the Selebi-Phikwe mining area, Botswana M. O. Schwartz Æ J. Kgomanyane Received: 29 January 2007 / Accepted: 29 May 2007 / Published online: 28 June 2007 Springer-Verlag 2007 Abstract Seepage from a tailings dam is the major source of groundwater pollution in the Selebi-Phikwe area, where mining of sulphidic nickel–copper–cobalt ore started in 1973 and will continue until 2014. The seepage water has a pH in the range of 1.7–2.8 and is strongly enriched in SO4 2– (5,680 g/L) and heavy metals (6,230 lg/L Ni, 1,860 lg/L Cu and 410 lg/L Co). The fracture aquifer affected by pollution from the dam exhibits a remarkable capacity of heavy-metal sorption. Most of the Ni, Cu and Co is scavenged at less than 500 m distance downgradient from the polluting source, whereas SO4 2– is not immobi- lized significantly. The heavy-metal sorption process is assumed to be due to surface complexation, which is sup- po
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