扬州古运河三湾段沉积物中重金属潜在生态风险评价及形态变化特征

扬州古运河是京杭大运河最古老的一段,为了解沉积物中重金属污染状况,采用Hakanson潜在生态风险评价扬州古运河三湾段沉积物中重金属Cr、Ni、Cu、Zn、Cd和Pb的风险水平,并对形态分布特征进行了研究。结果表明:扬州古运河六种重金属的含量均高于背景值,其中Cd含量为其背景值的13.15倍。沉积物中重金属的累积潜在生态风险指数RI高达456.55,沉积物的总体潜在生态风险等级为强。沉积物中Pb的主要赋存形态主要以铁锰氧化态存在,而Zn和Cd主要以酸可溶态形式存在,说明这三种重金属的潜在生态风险水平较高。

Potential Ecological Risk Assessment and Morphological Change Characteristics of Heavy Metals in the Sediment of Yangzhou Ancient Canal

Yangzhou's canal is the oldest section of the Beijing-Hangzhou Canal. The risk level of the heavy metals (Cr,Ni,Cu,Zn,Cd and Pb) in the sediment from SanWan section of Yangzhou ancient canal was researched by Hakanson potential ecological risk assessment method, their morphological distribution characteristics were investigated. The results show that concentrations of six heavy metals are higher than the background values; the content of Cd is more than 13.15 times the background value. The cumulative potential ecological risk index of six kinds of heavy metals in the sediment is 456.55, so the overall potential ecological risk degree of the sediment of Yangzhou ancient canal is strong. The sequential extraction experiment shows that the main speciation of Pb in the sediment is iron and manganese oxidation state, the speciation of Zn and Cd in sediment is mainly dissolvable and exchangeable state, which shows that Pb, Zn and Cd are the largest potential ecological risk elements.