Gold tailings as a source of waterborne uranium contamination of streams - the Koekemoerspruit (Klerksdorp goldfield, South Africa) as a case study - part I of III: uranium migration along the aqueous pathway

• DOI: 10.4314/wsa.v30i2.5067
• Publication Date: 2011-11-30T09:59:02Z
• Authors: Frank Winde; Peter Wade; Izak Jacobus Van ...
• Keywords: Uranyl

Tailings deposits from gold and uranium (U) mining in the Witwatersrand basin often contain elevated levels of radioactive chemo-toxic heavy metals. Through seepage, dissolved U other metals migrate tailings via groundwater into adjacent fluvial systems. The subsequent transport through flowing surface water is one most effective pathways distributing contaminants throughout biosphere. Mechanisms diffuse stream contamination, as well aqueous transportation were investigated. In this paper, geochemical data sediment samples Koekemoerspruit (a typical example a affected by South Africa) are analysed with regards to possible immobilisation mechanisms migrating solution. Ratios between solid phases for various water-sediment-systems along pathway indicated, unexpectedly, significantly lower mobility than system floodplain. Correlation parameters suggests co-precipitation calcium carbonate iron/ manganese-compounds main reason higher rate Owing redoxinitiated precipitation at interface reducing oxygenated within bottom sediments, latter act sink barrier sources. low retention highly sorptive floodplain sediments on hand explained formation neutral uranyl-sulphate-complexes, which prevent positively charged ion adsorbing onto negative surfaces clay minerals organic substances Evidence such complexes sulphate crusts extremely high concentrations, form topsoil due capillary fringe effects dry periods. Due their solubility, these easily rain, resulting concentration peaks runoff. WaterSA Vol.30 (2) 2004: 219-225