尾矿区污染土壤中重金属的形态分布及其生物有效性

采用BCR连续提取法对大宝山槽对坑尾矿区周围受污染的菜园土和水稻土中Cd、Pb、Cu和Zn的形态分布及其生物有效性进行了研究。结果表明，两种土壤中Cd、Pb、Cu和Zn的总量均超过国家土壤环境质量相应的标准。两种污染土壤中Cd、Pb、Cu和Zn的形态分布差别不大。Cd主要分布在残渣态中，占总量的60％以上，Cd各形态含量的分配顺序均为：残渣态〉酸提取态〉可氧化态〉可还原态；Pb以可还原态和残渣态为主，占总量的92％以上；Cu各形态含量的分配顺序均为：残渣态〉可还原态〉酸提取态〉可氧化态，以残渣态为主，占总量的59％以上；Zn在土壤中以残渣态占绝对优势，占总量的90％以上。菜园土和水稻土重金属生物有效性以Ph为最高，Zn为最低。

Species Distribution and Biological Effectiveness of Heavy Metals in Contaminated Soils of Mine Tailing Area

The species distribution and biological effectiveness of heavy metals (Cd, Pb, Cu and Zn) in contaminated paddy soil and vegetable soil around Caoduikeng mine tailing area of Dabaoshan in Guangdong Province were studied by the method of BCR sequential extraction procedure. The results showed that the total concentrations of Cd, Pb, Cu and Zn in both contaminated soils all exceeded the maximum permissible limits (GB15618-1995, pH<6.5, Cd 0.30 mg/kg, Zn 200 mg/kg, Pb 250 mg/kg, Cu 50 mg/kg) that set by State Environmental Protection Agency (SEPA) for soils.in China.The species distribution of Cd, Pb, Cu and Zn in both contaminated soils has no obvious different. Cd was mainly dominated by the residual state, it accounts for more than 60% of the total contents, and the each state contents of Cd distributed as follows by the order of residual ＞ acid-extractable ＞ oxidizable > reducible; Pb was mainly dominated by the reducible and residual states, they account for more than 92% of the total contents; Cu was mainly dominated by the residual state, it accounts for more than 59% of the total contents, and the each state contents of Cu distributed as follows by the order of residual > reducible > acid-extractable > oxidizable; Zn was mainly dominated by the residual state, it accounts for more than 90% of the total contents. The highest and the lowest biological effectiveness of heave metals in both soils were Pb and Zn, respectively.