芜湖市龙窝湖湿地土壤重金属污染特征及潜在生态风险评价

分析了不同人类活动方式下芜湖市龙窝湖湿地土壤镍（Ni）、铬（Cr）、镉（Cd）、铅（Pb）、铜（Cu）和锌（Zn）含量差异，采用污染指数法、潜在生态风险指数法和沉积物质量基准（SQG）比较法对湿地土壤重金属污染特征和潜在生态风险进行评价。结果表明：6个样地土壤重金属含量只有Cd含量（0．76—3．67mg／kg）显著超过土壤环境质量二级标准（GB15618—1995）；6个样地土壤Cd和Cu含量与塘式水产养殖湿地、网式水产养殖湿地、垃圾倾倒地下游湿地和垃圾倾倒地土壤Pb和Zn含量超过土壤背景值，而6个样地土壤Ni和Cr含量与湖泊底泥和耕地土壤Ph和Zn含量未超标；土壤6种重金属综合污染指数为垃圾倾倒地下游湿地（25．4）〉网式水产养殖湿地（25．3）〉塘式水产养殖湿地（23．1）〉垃圾倾倒地（19．2）〉耕地（8．2）=湖泊底泥（8．2）；土壤6种重金属综合潜在生态风险指数为网式水产养殖湿地（603．6）〉垃圾倾倒地下游湿地（595．5）〉塘式水产养殖湿地（538．4）〉垃圾倾倒地（439．9）〉耕地（145．6）〉湖泊底泥（136．6）。土壤cd含量高是导致湿地土壤重金属较高污染（Cd单项污染指数占综合污染指数：49％～76％）和存在严重潜在生态风险（Cd单项潜在生态风险指数占综合潜在生态风险指数：88％～96％）的关键元素。基于沉积物质量基准比较法的潜在风险评价结果表明湿地土壤存在M、Cd和Cu污染的中等潜在生态风险。

Characteristics and Potential Ecological Risk of Soil Heavy Metal Pollution in the Longwo Lake Wetland in Wuhu City, Anhui Province

Ni, Cr, Cd, Pb, Cu and Zn contents in soil were analyzed, and the pollution index and the potential ecological risk index of soil heavy metals were calculated to estimate soil pollution in the Longwo Lake Wetland in Wuhu City. The results showed that soil Cd contents （0.76 -3.67 mg/kg） seriously exceeded soil quality standard （GB 15618-1995） in all 6 studied fields, while other heavy metal contents were under soil quality standard. Soil Cd and Cu contents in all 6 studied fields and soil Pb and Zn contents in pond fishery wetlands, net fishery wetlands, rubbish wetland and rubbish field exceeded soil element background contents, otherwise soil Ni and Cr contents in all studied fields and soil Pb and Zn contents in lake sediment and cultivated land were under soil element background contents. Pollution indices of all soil heavy metals in studied fields cultivated land decreased with the following tendency ： rubbish dumping wetland （25.4） 〉 net fishery wetland （ 25.3 ） 〉 pond fishery wetland （ 23.1 ） 〉 rubbish dumping field （ 19.2 ） 〉 cultivated land （8.2） = lake sediment （8.2）. Potential ecological risk indices of all the 6 soil heavy metals decreased with the tendency： net fishery wetland （603.6） 〉 rubbish dumping wetland （595.5） 〉 pond fishery wetland （538.4） 〉 rubbish dumping field （439.9） 〉 cultivated land（145.6） 〉 lake sediment （136.6）. Soil Cd was the key element inducing soil heavy metal pollution and serious potential ecological risks. Comparing to sediment quality guide line, soil Ni, Cd, and Cu induced a medium potential ecological risk in Longwo Lake Wetlands in Wuhu City.