南京市某闭库铜矿尾矿库土地再利用风险评估

Risk Assessment of Land Reuse in Tailings Pond of a Copper Mine in Nanjing

针对尾矿库闭库后安全再利用问题,本研究以南京市某闭库铜矿尾矿库为例,设置28个库区土壤采样点,6个周围农田土壤采样点,2个库区排水涵管采样点,测定样品中砷(As)、铅(Pb)、镉(Cd)、铬(Cr)、铜(Cu)、镍(Ni)和锌(Zn)元素的含量及pH,关注闭库后存在的重金属污染风险。结果表明:该尾矿库区土壤呈弱碱性;两个排水涵管的水样未受到重金属污染;土壤样品中重金属Ni未检出,但其余重金属元素富集明显,其中As、Cd和Cu含量最小值大于南京地区土壤元素背景值,Pb、Zn和Cr超过南京市土壤元素背景值的点位所占比例分别为94.12%、85.29%和5.88%。该尾矿库区土壤存在一定的重金属污染和生态风险,其中Cd的潜在生态风险系数显示超过一半的点位存在较高风险,须重点关注。潜在生态风险指数法评价结果表明50%的点位存在中等风险;健康风险评价结果表明,这6种重金属元素对成人的健康影响处于可忽略水平。

Aiming at the problem of safe utilization of tailings pond after closure,this study takes a closed copper mine tailings pond in Nanjing as an example,and sets 28 soil sampling points in reservoir area,6 soil sampling points in surrounding farmland,and 2 drainage culvert sampling points in reservoir area.The contents of arsenic(As),lead(Pb),cadmium(Cd),chromium(Cr),copper(Cu),nickel(Ni)and zinc(Zn)and pH in the samples were determined,and the risk of heavy metal elements contamination after the storage was concerned.The results show that the soil in the tailings reservoir area is weakly alkaline;The water samples of the two drainage culvert pipes were not contaminated by heavy metals.The contents of As,Cd and Cu were higher than the background values of soil elements in Nanjing,and the percentages of Pb,Zn and Cr exceeding the background values of soil elements in Nanjing were 94.12%,85.29%and 5.88%respectively.There are heavy metal pollution and ecological risks in the soil of the tailings pond area,and the potential ecological risk coefficient of Cd shows that more than half of the points have high risks,which needs to be paid attention to.The evaluation results of potential ecological risk index show that 50%of the sites had moderate risk.The results of health risk assessment show that the health effects of these 6 heavy metals on adults were negligible.