Browsing by Author "Pohl, Walter"

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    Exploratory geochemical assessment of stream water and sediment contamination in Gatumba tin and tantalum mining district, Rwanda.
    (2009) Flügge, Judith; Muwanga, Andrew; Trümper, Kerstin; Zachmann, Dieter; Pohl, Walter
    Stream waters are not contaminated with dangerous inorganic elements. According to WHO guidelines, these waters are acceptable for lifelong consumption without risk to health. Note, however, that microbial waterborne disease vectors were not investigated. Stream sediments generally have relatively low contents of most elements that may be derived from pegmatites. Of mine-related contaminants, only uranium and arsenic exceed their respective average crustal abundance. Both appear to be higher near former mine sites but this is probably not caused by mining. Causes are rather primary hydrothermal and secondary supergene dispersion, and recent mobilisation because of intensive agricultural use. Yet at present, the welfare of the local population is not threatened. The most serious hazard is human interference with groundwater by abstracting drinking water either from wells in valley fill or from deeper horizons of the regolith. Overall, our work suggests that past mining at Gatumba caused little dispersion of deleterious elements.
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    The geochemical signature of rare-metal pegmatites in the Central Africa Region: Soils, plants, water and stream sediments in the Gatumba tin–tantalum mining.
    (Journal of Geochemical Exploration, 2014) Nieder, Rolf; Weber, Tobias; Paulmann, Inga; Muwanga, Andrew; Owor, Michael; Naramabuye, Francois; Gakwerere, Francis; Biryabarema, Micheal; Biester, Harald; Pohl, Walter
    We studied trace elements in soils, plants, water and stream sediments in the Gisuma–Kibilira catchment of the Gatumba area of western Rwanda which has a long tradition of artisanal to small-scale tin–tantalum mining from rare-metal pegmatites. The geochemical fingerprint of soil, plant, water (springs and surface water in dry and rainy seasons) and stream sediment samples reveals elevated concentrations of Li, Rb, Cr, and Cs, but low As and U abundances at or below the global average. Trace element contents of soils and most plant materials are below internationally accepted guideline values. All water samples analyzed meet the World Health Organization (WHO) drinking water guidelines, and the stream sediments are below critical values of Dutch environmental standards. These data provide a baseline for environmental impact studies for rare-metal mining projects in the Central Africa Region