鄱阳湖湿地土壤中Cu Zn Pb Cd的形态研究

Speciation of Cu,Zn,Pb,Cd in the Wetland of Poyang Lake

针对乐安河上游铜矿开采带来的鄱阳湖湖体东部重金属污染的问题,采用Tessier法对鄱阳湖湿地土壤中Cu、Zn、Pb、Cd的化学形态以及重金属形态与植物富集的相关关系进行了研究。结果表明,鄱阳湖土壤中Cu、Pb、Zn主要以有机结合态和残渣态为主,水溶态和交换态等生物有效性态含量很少。Cd的水溶态、交换态和铁锰氧化物态较其他元素高。相关分析和偏相关分析均显示植物中重金属含量与其生存环境中的重金属含量直接相关,植物对重金属的富集能力表现出Zn>Cu>Cd>Pb的趋势。

As a result of indust,＇ialization, the modem world has left a legacy of metal contamination throughout the environment. These industrial activities, such as smelting, foundries, and finishing, have introduced large concentrations of metals into many different environments, including aquatic systems identifying the chemical forms of toxic metals is of vital importance for a realistic assessment of the chemical risk posed by their presence in soils and selecting effective remediation technologies. Consequently, the definition of the different chemical forms （i.e., chemical speciation） of metals becomes a key issue. In this study, the heavy metals （Cu, Pb, Cr, Cd, Zn and Ni） in the wetland soil in Poyang Lake were fractionated to water soluble, exchangeable and carbonate bound, Fe-Mn oxide bound, organic matter and residual bound by a four-stage sequential extraction procedure. All analysis of Cu, Zn, Pb and Cd in each extractant was performed using atomic absorption spectroscopy. Plant bioaccumulation factor and the Correlation and partial correlation coefficients among speciation of Cu, Zn, Pb and Cd from soils were also studied. The results showed that the organic matter-sulfide and residual bound fraction was the main speciation of Cu, Zn, Pb; the soluble and exchangeable fraction （bioavailable speciation） and Fe-Mn oxides fraction of Cd were higher than those of other three metals. The plant uptake coefficients for heavy metals（the soluble and exchangeable speciation） ranked in the following order： Zn 〉Cu 〉Cd 〉 Pb.