Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Bioavailable metals in soils contaminated by mining and processing of base metal ores in Namibia
Abstract
The bioavailability of metals in heavily contaminated soils studied in the areas of Rosh Pinah and Tsumeb in Namibia turned out to differ significantly. Their enhanced bioavailability in the Tsumeb region is obviously caused by fine grain-size of solid emissions from local smelter and their fast weathering after deposition in semi-humid climate. The bioavailability of metals in the desert region of Rosh Pinah is lower. Approximately 73 % of chemical variability found in soil samples in the area of Rosh Pinah can be attributed to two factors. The first one is ascribed to sulfide fallout from crushers and ore concentrate damping grounds in which the content of bioavailable metals is low. The second factor is interpreted as fallout from a tailings impoundment that has been exposed to prolonged weathering, oxidation of sulfides and subsequent transport of sulfates. The fallout from tailings impoudment contains mostly metals in bioavailable form.
