太湖表层沉积物重金属赋存形态分析及污染特征

为了解太湖表层沉积物中重金属的污染状况,对太湖表层沉积物中4种重金属（Cd、Pb、Cu、Zn）的含量及空间分布分别进行了对比研究,并采用BCR三步分级提取法分析了太湖表层沉积物中4种重金属（Cd、Pb、Cu、Zn）不同赋存形态的含量,评估了这4种重金属的生物有效性,最后采用潜在生态危害指数法对重金属污染程度及潜在生态危害进行了评价.结果表明,太湖表层沉积物中4种重金属元素均有一定程度的富集,其中Cd的富集程度最为严重;赋存形态分析表明4种金属均主要以可提取态形式存在,各元素生物有效性即可提取态含量排序为：Cd〉Pb〉Zn〉Cu;潜在生态危害指数法评价结果表明,元素Cd为太湖表层沉积物中最主要的污染元素,且具有较强的生态危害.其次是Pb,Cu和Zn则较为轻微.4种重金属潜在生态危害由大到小排序为：Cd〉Pb〉Cu〉Zn.

Speciation and Pollution Characteristics of Heavy Metals in the Sediment of Taihu Lake

To explore the condition of heavy metal pollution of Taihu Lake, the contents and spatial distribution of Cd, Pb, Cu and Zn in surface sediments of Taihu Lake were studied respectively. BCR three stages sequential extraction procedure was applied to investigate the speciation and contents of four heavy metals (Cd, Pb, Cu, Zn) in the surface sediments of Taihu Lake. And the bioavailability of these four heavy metals was also determined preliminarily. At last the contamination and potential ecological risk of these elements were evaluated by potential ecological risk index. The results indicated that all 4 elements in surface sediments of Taihu Lake were enriched to some extent, especially Cd. All of these four metals existed mainly in extractable fractions which included weak soluble fraction, reducible fraction and oxidisable fraction, and the bioavailability of four metals varied with a descending order of Cd>Pb>Zn>Cu. The comprehensive assessment results showed that Cd was the primary element with high ecological risk while Pb, Cu, Zn were slight,and the order of ecological risk was Cd>Pb>Cu>Zn.