利用化学萃取法研究长春市土壤重金属化学形态及其影响因素

利用化学萃取法研究长春市土壤重金属化学形态， 分析其化学形态与土壤负荷水平、 理化性质的关系表明， 土壤中Pb和Cu主要以残渣态和有机结合态为主； Cd主要以残渣态和交换态为主； Zn主要以残渣态和铁锰氧化态为主. Cd的活性形态含量最高， 为31.98%. 交换态Cd和Zn含量及活性与土壤重金属负荷水平呈正相关； Cu和Pb铁锰氧化态的含量随负荷水平增加而下降； Zn和Pb碳酸盐结合态与负荷水平无关. 交换态Cd与土壤阳离 子交换量呈显著正相关， 而Cd的活性与土壤阳离子交换量呈显著负相关； 在碱性条件下， Cd， Cu， Pb和Zn的碳酸盐结合态与pH呈正相关； 重金属铁锰氧化态含量随着氧化还原电位的增加而降低， 而残渣态相反. Cu有机结合态与有机质呈显著正相关.

Chemical Speciation of Some Heavy Metals in Urban Soils in Changchun Studied by Chemical Extraction and Influencing Factors

The urban soil samples in Changchun were studied for the potential chemical speciation of some heavy metals by chemical extraction in order to analyse the relationships between the chemical speciation and the total heavy met al as well as the physicochemical characteristics of urban soils. The results sh ow that Pb and Cu are mainly in residual and organic phases, Cd is largely associated with the residual and exchangeable fractions, while Zn is largely associated with the residual and Fe-Mn oxide phases. The highest percentage of Cd associated with available fractions is 31.98%. The total metal contents have direct influences on the exchangeable and available Cd and Zn contents, inverse influences on the Fe-Mn oxide Cu and Pb contents, and no influences on　the carbonate Zn and Pb contents. The exchangeable Cd contents are directly correlated with cation exchange capacity, and the available Cd contents are inversely correlated with cation exchange capacity. The carbonate fractions are directly correlated with pH, and Fe-Mn oxide fractions are directly correlated with oxidation-reduction potential. The organic Cu contents are directly correlated with organic contents.