复垦尾矿库重金属分布及生态风险评价

摘要

In order to assess the ecological risk of tailings, protect ecological environment and achieve sustainable development, the vertical distribution characters of the heavy metals Pb, Zn, Cu and As in a tailings were investigated, and the pollution and potential ecological hazards degree were assessed. In addition to geoaccumulation index and ecological hazards index, the geoaccumulation index and Nemerow index were combined to evaluate the comprehensive pollution of heavy metals. The results show that the vertical distributions of heavy metals are different. The heavy metal concentration in the reclamation soil is lower but it is still higher than the soil background value. The heavy metal concentration in the interface between the soil and tailings is the highest, the pollution degree is the strongest. The pollution degrees in the tailings layer and deep area are more severe. Among these heavy metals, the pollution degree of Cu is the slightest, and the pollution degrees of Pb, Zn and As are different in different depth. The contribution orders of the four heavy metals on the total ecological hazards index from big to small are As, Pb, Zn, Cu. The effect that simple covering soil on tailings to reduce heavy metal hazards is not significant, other effective measures should be combined to treat heavy metal pollution.%为评估尾砂矿生态风险，保护生态环境，实现可持续发展，研究某铅锌尾矿库中Pb、Zn、Cu、As 4种重金属的垂向分布并对其污染程度和潜在生态危害进行评价。除使用地累积指数法和生态风险指数法，结合地累积指数法和内梅罗综合指数法来评价多种重金属综合污染情况。结果表明：重金属在垂向上的分布不尽相同，复垦土层重金属含量较下层小但仍超过土壤背景值；土层与尾砂交界处，重金属出现富集现象，污染程度最大；尾砂层和深部区为中度或强污染。4种重金属元素Cu的污染最轻，Pb、Zn、As的在中度污染或强污染以上，对总的生态风险指数贡献率由大到小依次为 As、Pb、Zn、Cu。单纯覆土对减少尾矿库重金属危害效果不明显，应联合其他有效措施进行修复。