Fraction Distribution and Risk Assessment of Heavy Metals in Iron and Gold Mine Soil of Miyun Reservoir Upstream
密云水库上游金属矿区土壤中重金属形态分布及风险评价

Environmental pollution and risk assessment of heavy metals in soils of iron and gold mine areas of Miyun Reservoir upstream in Beijing were researched in this article. Soil and sediment samples were collected around the mine areas. The contents and extractable contents of heavy metals(Cd,Mn, Zn, Cu, Pb, Ni, V, Cr) were analyzed. Heavy metal contamination was evaluated by the Tucker3 model and risk assessment code (RAC). The results showed that the concentration of most heavy metals in mine areas were exceeded the soil background of Beijing. The fractions of heavy metals in soils were analyzed by BCR sequential extraction procedure. The results showed that exchangeable fraction content for Mn accounted for 20%-30% of the total concentration; exchangeable and Fe-Mn fractions contents for Zn, Cd, Pb respectively accounted for about 17%-24%,10%-23%,30%-45% of the total concentration; residual fraction contents for Cr, Ni, V accounted for more than 80% of the total concentration. The Tucker3 model further demonstrated that potential hazards of heavy metals in mine areas. The risk indices were 0.03%-55.18% and 3.94%-67.16% from Mn in soils of iron and gold mine areas of Miyun Reservoir upstream. The risk assessment of Mn had a high potential ecological risk. Other metals had a low potential ecological risk. The conclusion will provide scientific basis in mine environmental pollution control and protection of Miyun Reservoir in Beijing.