干旱区绿洲土壤中Cd,Pb,Zn形态分布与芹菜有效性

Form distributions of Cd,Pb and Zn and their availability to celery in arid oasis soil

以干旱区绿洲耕层土壤为研究对象,通过盆栽试验,利用Tessier连续提取法研究了原状土以及外源可溶性重金属Cd,Pb,Zn加入土壤后重金属形态分布,分析了土壤中重金属不同化学形态与芹菜有效性之间的关系。结果表明:原状土壤中Cd主要以铁锰氧化态和碳酸盐结合态形式存在,Pb和Zn主要以残渣态形式存在;随着重金属负荷的增大,三种重金属各形态质量分数均有不同程度的提高,Cd以可交换态和碳酸盐结合态为主要赋存形态,Pb和Zn均以碳酸盐结合态和铁锰氧化态为主要赋存形态。实验土壤中,对芹菜Cd吸收量贡献最大的分别为可交换态和碳酸盐结合态,对Pb吸收量贡献最大的分别是碳酸盐结合态和铁锰氧化态,对Zn吸收量贡献最大的分别是碳酸盐结合态和可交换态。

Soil samples were collected from the plowing layer of the arid oasis region and studied through pot experiments. Using Tessier sequential extraction, the distribution of chemical forms of heavy metals added in tested soil was investigated, as well as the relationship between the concentrations of chemical forms of studied heavy metals and their availability to celery. The results show that Cd existed mainly in Fe-Mn oxides bound form, while Pb and Zn mainly in residual fraction in the original soil. With the increasing amounts of heavy metals added into the soil, the concentrations of all five forms of the three metals increased to different extents. Exotic Cd of soil was found to be predominant in exchangeable form and carbonate-bound form, while exotic Pb combined with Zn was found predominantly in carbonate-bound form and Fe-Mn oxide-bound form. Cd of exchangeable form and carbonate-bound form, Pb of carbonate-bound form and Fe-Mn oxides bound form, Zn of carbonate-form and exchangeable form made the most contributions to the content of Cd, Pb and Zn in celery, respectively.