Environmental contamination of mercury from Hg-mining areas in Wuchuan, northeastern Guizhou, China

Total Hg and methyl-Hg were evaluated in mine wastes, soils, water, and vegetations from the Wuchuan Hg-mining areas, Guizhou, China. Mine wastes contain high total Hg concentrations, ranging from 79 to 710 μg g−1, and methyl-Hg from 0.32 to 3.9 ng g−1. Total Hg in soil samples range from 0.33 to 320 μg g−1 and methyl-Hg from 0.69 to 20 ng g−1. Vegetations present a high average total Hg concentration of 260 ng g−1, which greatly exceeds the maximum Hg concentration of 20 ng g−1 recommended by the Chinese National Standard Agency for food sources. The rice samples contain elevated methyl-Hg concentrations, ranging from 4.2 to 18 ng g−1. Stream water collected from Hg-mining areas is also contaminated, containing Hg as high as 360 ng l−1, and methyl-Hg reaches up to 5.7 ng l−1. Data indicate heavy Hg-contaminations and significant conversion of methyl-Hg in the study areas.