Mercury pollution due to gold mining in the Madeira river basin, Brazil

New results from an extensive survey on the mercury concentration in different environmental compartments (river water, suspended and bottom sediments, soil, and air), as well as in fish and human hair, from the gold mining area along the Madeira River, SW Amazon, are presented. Concentration of mercury in bottom sediments (up to 157 μg Hg · g-1dw) from small forest streams, close to the main mining areas, as well as in fish (up to 2.7 μg Hg · g-1ww) taken from Madeira tributaries, indicate heavy mercury contamination in this area. Air-mercury concentrations prove to be quite similar to control areas, but can reach very high levels in the vicinity of Au-Hg reburning locations. The mercury burden in human hair of up to 26.7 μg · g-1dw suggests high exposure in local populations.