Peatlands as Filters for Polluted Mine Water?—A Case Study from an Uranium-Contaminated Karst System in South Africa Part I: Hydrogeological Setting and U Fluxes

摘要

Located downstream of goldfields of the Witwatersrand basin, the Gerhard Minnebron (GMB) Eye—as major water source for downstream community of some 300,000 people—may be impacted on by mining-related water pollution especially with uranium (U). Containing up to 5 m-thick deposits of peat that is frequently reported to act as a filter for U and other heavy metals, this paper is the first part of a series that aims to quantify the ability of the GMB peatland to act as buffer against current and future U pollution. In a first step, this paper outlines the geohydrological conditions and discusses how deep–level gold mining impacted on the dolomitic aquifers. Subsequently, the potential influx of U into the wetland is estimated and associated sources and pathways analyzed. Finally, a model is proposed explaining the significant differences in degree and dynamics of U observed within a single groundwater compartment.