[Environmental quality of soil polluted by mercury and lead in polymetallic deposit areas of western Hunan Province].

The environmental quality of soil polluted by mercury and lead in typical polymetallic deposit areas of western Hunan province and its natural and human causes were studied. It was found that western Hunan province is a high regional geochemical abnormal region on mercury and lead. The concentrations of mercury and lead in soils in mercury deposit areas were 1 315 and 3.1 times higher than that of the average background of soils in China respectively, while those in soils in lead-zinc deposit areas were 14.8 and 16.1 times higher. Using geoaccumulation index developed by Muller, it was found that either mercury deposit area or lead-zinc deposit area in western Hunan province is polluted by the two elements, the majority soils in mercury deposit areas are seriously polluted by mercury with middle polluted or light polluted by lead, while the majority soils in lead-zinc deposit areas are middle polluted or middle-heavily polluted by lead and middle-heavily polluted by mercury. The sources of metal pollutants in soils in the deposit areas are natural and human causal, the spatial distribution of mercury and lead are dominated by original geochemical situation but seriously affected by human mining activities.