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

研究了北京市密云水库上游金属矿区土壤中重金属环境污染和风险评价.从矿区周围采集了土壤和沉积物样品,分析了铁矿开采区和金矿开采区土壤样品中Cd、Mn、Zn、Cu、Pb、Ni、V、Cr的总量及提取态重金属含量,采用Tucker3模型、风险评价编码法(RAC)探讨了矿区土壤中重金属污染程度.研究表明,金属矿区土壤中大多数重金属超出北京市土壤背景值.采用BCR逐级提取法分析土壤中重金属形态,矿区土壤中Mn可交换态含量占总量的20%～30%;Zn、Cd、Pb可交换态和易还原态(Fe-Mn氧化态)含量之和约分别占总量的17%～24%、10%～23%、30%～45%;Cr、Ni、V残渣态含量占总量的80%以上.Tucker3模型分析进一步表明矿区重金属的潜在危害性.密云水库上游铁矿开采区和金矿开采区土壤中Mn的风险指数为0.03%～55.18%和3.94%～67.16%,处于中高潜在生态风险,其它重金属潜在生态风险较低.该结论将为北京市矿山环境污染防治和密云水库的保护提供科学依据.

Fraction Distribution and Risk Assessment of Heavy Metals in Iron and Gold Mine Soil of Miyun Reservoir Upstream

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.