引江济太沿程小型过水湖泊典型重金属富集特征及潜在生态风险

Enrichment Characteristics and Potential Ecological Risks of Typical Heavy Metals in Small River-Passing Lakes along the Water Diversion Project of Yangtze River to Taihu Lake

为明晰引江济太沿程上小型过水湖泊漕湖中典型重金属的富集特征和潜在生态风险,通过对河湖系统表层沉积物中9种重金属(Cr、Co、Ni、Cu、Zn、Cd、Pb、Sb和Hg)的含量分析,研究和分析了重金属的富集程度、生态风险和潜在来源。结果表明,除Co、Cr和Pb外,其余6种金属的平均含量均超过江苏省土壤背景值,Cd约是背景值的12.38倍,污染最为严重;重金属空间分布上主要集中在漕湖入湖口、圩区口、东西向中线附近以及支流口(CH11)处。地累积指数和潜在风险指数表明Cd为中污染,Zn、Sb和Hg表现为低污染水平;Cd作为主要的环境风险因子,表现为极高生态风险,表层沉积物中重金属污染整体表现为高风险水平。漕湖沉积物中重金属的富集受周边工业和农业活动的影响较大,Cd的污染与工业生产、引水和农业面源等关联较大。

In order to investigate the enrichment characteristics and potential ecological risks of typical heavy metals in the sediments of Caohu Lake which is a small river-passing lake along the water diversion project of Yangtze River to Taihu Lake,this study analyzed the contents of 9 heavy metals(Cr、Co、Ni、Cu,Zn,Cd,Pb,Sb and Hg)in the river-lake system,then evaluated the enrichment and as well as traced the sources of those heavy metals.The results demonstrated that the mean contents of metals except Cr,Co and Pb were beyond the background value of Jiangsu Province.In particular,the mean content of Cd was about 12.38 times the background value,presenting the greatest potential ecological risk.The high contents of heavy metals were mainly distributed at the inlet of Caohu Lake,outlets of polder areas,the east-west middle line of Caohu Lake and tributaries(CH11).The geo-accumulation index showed that Cd were in moderate pollution status,and Zn,Sb,and Hg were in low pollution.According to the assessment of potential ecological risk,all the surface sediments showed high potential ecological risk,Cd had very high ecological risk and was the main environmental risk metal.The enrichment characteristics of most heavy metals in Caohu Lake were greatly affected by the surrounding industrial and agricultural activities,and Cd pollution was closely related to industrial production,water diversion and agricultural nonpoint sources.