铜陵狮子山矿区土壤重金属污染特征及生态风险评价

Characteristics and ecological risk assessment of polluted soil by heavy metals in Shizishan,Tongling

选择安徽铜陵狮子山矿区5种不同土地利用类型(采矿区、选矿区、堆矿区、尾矿区及周边菜园)的土壤为主要调查研究对象,采集样品76份,分析了土壤重金属含量和形态特征,并对重金属污染程度和潜在生态危害进行了评价.结果表明,铜陵狮子山矿区表层土壤中重金属Cu、Pb、Zn和Cd的平均含量均超过铜陵市土壤背景值,且不同片区土壤中重金属含量差异较大.各片区土壤的重金属元素以残渣态为主,可氧化态比例最小.采用相关性和主成分分析可知,重金属元素之间存在一定的正相关性,Cu、Pb与Zn之间相关性尤为显著(P<0.01),推断Cu、Pb和Zn来源相似.单因子指数法结果表明,重金属元素的污染程度大小为Cu>Cd>Pb>Zn.内梅罗综合污染指数法结果表明,不同片区土壤重金属综合污染指数大小为:堆矿区>选矿区>采矿区>菜园>尾矿库区,其中选矿区和堆矿区污染尤为严重.综合潜在生态危害指数来看,尾矿区属于轻度危害,采矿区和菜地属于中度危害,堆矿区和选矿区属于很强危害.

Soil samples from five different types of land-use zones in Shizishan, Tongling, Anhui （milling, mining and tailing, heap mining area and the garden around them） were chosen as the study object, and a total of 76 samples were collected. The contents of heavy metals in soil and morphological characteristics were analyzed, and pollution level and potential ecological risk of heavy metals were evaluated. Results showed that the mean contents of Cu, Pb, Zn and Cd in soil samples exceeded the corresponding background values in Shizishan, and the contents of heavy metals varied significantly in different zones. The residual phase is the main species of the heavy metals, and the proportion of oxidation state is small. Correlation and principal component analysis showed that there was a positive correlation between the heavy metals, and the correlation between Cu, Pb and Zn was significant（P〈0.01）, which suggests Cu, Pb and Zn in the soil of Shizishan came from the same sources.Single factor index results showed that the pollution degree was in the following order： Cu〉 Cd〉Pb〉Zn. The Nemerow integrated pollution index of the four areas ranked as follows ： heap mining area〉milling area〉mining area〉garden〉 tailings area, heap mining area and milling area pollution is particularly serious. The potential ecological risk index shows that tailings area is at a slightly hazard harm, mining area and garden are at moderate hazard levels, milling area and heap mining area are at very high hazard levels.