太湖表层沉积物中重金属形态分布及其潜在生态风险分析

Speciation distribution and potential ecological risk assessment of heavy metals in sediments of Taihu Lake

利用BCR 3步提取法对太湖37个表层沉积物样品中重金属Ni、Cu、Zn和Pb的形态进行调查研究,并基于重金属形态评价方法(RSP)对太湖沉积物中4种重金属的潜在生态风险进行了初步评价.结果表明,太湖表层沉积物中Ni、Cu、Zn和Pb含量显著高于太湖沉积物背景值,分别超出背景值80.3%、13.5%、25.9%和69.6%,表现出明显的累积效应.残渣态和Fe-Mn氧化物结合态是太湖表层沉积物中4种重金属的主要赋存形态,4种重金属的可提取态比例均大于50%,具有较高的二次释放潜力.从RSP污染指数分析,太湖表层沉积物中4种重金属的潜在生态风险大小为为Ni>Zn>Cu>Pb,表层沉积物中可提取态重金属的空间分布特征明显,表现为北部湖湾>西太湖>

BCR three stage sequential extraction procedure was applied to examine the speciation and concentration of four heavy metals（Ni,Cu,Zn and Pb） in sediments of Lake Taihu, and the potential ecological risk of these heavy metals was assessed based on the rations secondary phase and primary phase （RSP）. Concentrations of heavy metals in surface sediments were significantly higher than the background value of Taihu Lake sediment, which was 80.3%, 13.5%, 25.9%, 69.6% beyond the background value of Ni, Cu, Zn, Pb. The major speciation of four heavy metals were Fe-Mn oxide fractions and residue fraction, the percentage of fractions extracted form in total content was greater than 50%, the four heavy metals had a high potential for secondary release.Base on the RSP, the potential ecological risk of heavy metals was in the descending order of Ni, Zn, Cu and Pb. Total content of fractions extracted of heavy metals in the spatial distribution of apparent north bay〉west lake〉other regions.