Peatlands as Filters for Polluted Mine Water?—A Case Study from an Uranium-Contaminated Karst System in South Africa—Part IV: Quantifying the Chemical Filter Component

Abstract: This is the final part of a paper series on the ability of peat to filter uranium (U) from mining-polluted water. The focus is on the characterization and site-specific quantification of the chemical component of the filter model introduced in Part II. Based on U levels in different sediment-water systems of the study area that were analyzed in this paper, peat generally displays the highest geochemical U enrichment even though absolute U levels are relatively low. Results of batch experiments suggest that peat removes U from local mine waters exceptionally well, reaching a removal efficiency of close to 100%. However, almost all of the initially sorbed U is released again on subsequent contact with clean dolomitic water. A synoptic summary of the findings presented in Parts I to IV concludes the paper series.