[Chemical speciation and pollution characteristics of soil mercury in mercury deposit area of Western Hunan-Eastern Guizhou province].

By the BCR extraction procedures and HG-ICP-AES technique, the chemical speciation and pollution characteristics of soil mercury in typical mercury deposit areas of Western Hunan-Eastern Guizhou province were studied. It was found that the concentrations of mercury in soils are dominated by residual form, followed by organic-sulfide form. Fe-Mn oxides and acid-exchangeable form are rather low. The percent of the four mercury species in soils are 85.77%, 12.44%, 0.93% and 0:86%, respectively. The total concentrations and each species of mercury in soils show positive relationship with the concentration of sands, and negative relationship with the concentration of clays in soils. They also increase with the soil pH value. Mercury concentration in soils has spatial changes. In general, the concentrations in the surface soil are higher than those of sub-surface soils. Furthermore, the concentrations rapidly decrease with the distance from the pollution source increased and vary among different soil samples from different location and land use type. The results indicated that exogenous mercury pollution caused by human activities provides significant influence on environmental toxicity and pollution characteristics of mercury in soils of mercury deposit area.