Potential environmental impact resulting from inadequate remediation of uranium mining in the Karoo Uranium Province, South Africa

Inadequate remediation of uranium mining in the Karoo Uranium Province, South Africa led to a disused open pit and inclined shaft, uranium ore in stockpiles and barrels, as well as other mining related equipment. Land owners were unaware of the potential threat of uranium and coherent heavy metals resulting in livestock grazing amongst ore stockpiles and drinking from contaminated water supplies. Land owners consequently used stockpiled uranium ore for gravel road maintenance and construction of farmhouse foundations. The concentration of the radioactive gas radon (Rn-222) was monitored in the aforementioned farmhouse and reached 835 Bq.m(-3), thus exceeding the concentration limitations (150 Bq.m(-3)) for radon gas in dwellings set by the United States Environmental Protection Agency. Lycium cinereum, Fingerhuthia africana, Aristida congesta congesta and Phragmites australis growing within these mining locations revealed high concentrations Of uranium and molybdenum in leaves and roots. Lycium cinereum were found to accumulate molybdenum up to 650 ppm in some leaves. Uranium readily accumulates in the roots of some of the species, whilst only a fraction is translocated to the leaves. Plants were also subjected to protein profile studies revealing a general tendency that with an increase in uranium and molybdenum concentrations, protein concentrations in the leaves tend to decrease. These fauna serve not only as a toxicological hazard for grazing livestock, but also as potential phytore-mediators of polluted soils. Xenopus laevis were found to reside within a water filled open pit where uranium and molybdenum concentrations reach 20 mg/l and 4 mg/l respectively. These aquatic organisms contain high hepatic, renal and bone concentrations of uranium and molybdenum. Histological sections of liver and kidney revealed anomalous levels of lymphocytes, indicative of infection or neoplasia, possibly as a result of heavy metal uptake.