不同淋洗剂对污染土壤重金属形态分布的影响研究

Effects of different eluents on speciation analysis of the heavy metals in contaminated soil

以上海市某建设用地的重金属污染土壤为研究对象,对其理化性质和污染特征进行分析,通过Tessier连续提取法分析了经过不同淋洗剂淋洗后土壤中镍铜铅等重金属的形态分布情况。结果表明:土壤样品中重金属镍的含量显著超标,铜和铅的含量均未超标;在形态分布上,均以碳酸盐态、铁锰氧化态和残渣态为主。土壤中的镍元素经过柠檬酸淋洗后打破了各个形态的平衡,使土壤中的镍从残渣态解析并向铁锰氧化态迁移;土壤中的铜在盐酸淋洗后残渣态含量降低,迁移性能提高,而经过柠檬酸淋洗后碳酸盐结合态含量降低,使土壤中的铜元素趋于更加稳定的状态;与铜和镍相比,土壤中的铅更容易发生迁移,且在柠檬酸淋洗后铁锰氧化态含量有所降低。该研究为今后重金属污染土壤淋洗修复提供理论依据和实践参考。

The heavy metal contaminated soil in a construction land in Shanghai was taken as the research object,and the physical and chemical properties and pollution characteristics of heavy metal contaminated soil were analyzed.The speciation distribution of heavy metals(nickel,copper and lead)in soil washed with different leaching reagents was analyzed by Tessier continuous extraction method.The results showed that the content of nickel in soil samples exceeded the standard significantly,while the content of copper and lead did not exceed the standard.In terms of morphology distribution,they were mainly carbonate state,iron manganese oxidation state and residue state.After leaching with citric acid,nickel in soil breaks the balance of various forms,which caused the decomposition of nickel in soil from the residue state to transfer to the oxidation state of iron and manganese.After leaching with hydrochloric acid,the content of residual copper in soil decreased and its migration performance improved,while after leaching with citric acid,the content of carbonate bond decreased,so that the copper in soil tended to be more stable.Compared with copper and nickel,lead migrated more easily in soil,and the content of iron and manganese oxidation state decreased after citric acid leaching.Finally,this study provided a theoretical basis for leaching and remediation of heavy metal contaminated soil in the future.