铅锌尾矿库周边土壤重金属污染特征及环境风险

摘要

以尾矿库周边土壤为研究对象，用改进BCR法探讨Zn、Pb、Ni、Cu、Cr形态特征，用污染因子Cf和风险评价代码RAC评估环境风险。结果表明：Pb污染最重，总量是区域背景值的2倍多，污染剖面各重金属总量垂向分布均匀，污染已扩散至1 m深；5种金属均主要以残渣态存在，有效态、可交换态Pb质量占比均高于其他4种金属，与表层土壤相比，中、下层污染剖面各金属以更稳定的形态存在；Zn、Ni、Cu、Cr在表层或污染剖面土壤均存在低风险，部分点位Pb存在中度风险。%Taking soils around tailings reservoir as research object, speciation characteristic of lead (Pb), zinc (Zn), nickel ( Ni) , copper ( Cu) , chromium ( Cr) were investigated by modified BCR method, and environmental risks were evaluated by Cf and RAC. Results showed that:Pb pollution was the most serious, content of which was more than 2 times of regional background value, and contents of heavy metals in the pollution profiles were vertically uniform, indicating pollution has spread to 1 m. All heavy metals were existed mainly in the fraction of residue, percentage contents of Pb in available and exchangeable fraction were higher than other 4 metals, compared with topsoil, heavy metals in the middle and lower soil of pollution profiles were more stable. Zn,Ni,Cu,Cr existed low risk in the surface or profile soil, Pb existed medium risk in some sites.