模拟酸雨对污染土壤中Cd、Cu和Zn释放及其形态转化的影响

Effects of simulated acid rains on Cd, Cu and Zn release and their form transformation in polluted soils.

研究了模拟酸雨连续浸泡下污染红壤和黄红壤中重金属释放及形态转化。结果表明,随着模拟酸雨pH值下降,污染土壤中重金属释放强度明显增大;Cd、Zn释放量与酸雨pH值呈线性极显著负相关.Cu与酸雨pH值呈线性显著负相关。模拟酸雨作用下,污染红壤和黄红壤中Cd均以交换态为主;Cu则以有机结合态和氧化锰结合态为主;Zn在污染红壤中以残留态和交换态为主,在污染黄红壤中以残留态和有机结合态为主。土壤有机质含量和阳离子交换量对Cd、Cu、Zn的释放产生一定的影响并影响Cd、Zn的形态转化,但对Cu形态转化影响不明显,随着模拟酸雨酸度增大,污染红壤和黄红壤中重金属Cd、Cu的生物可利用态明显增多,但难解吸态Zn向生物有效态转化效应不明显。

The release and form transformation of Cd, Cu, and Zn in polluted red soil and yellow red soil affected by simulated acid rains were studied through batch equilibrium experiments. The results showed that the release of test heavy metals increased significantly with decreasing pH value of simulated acid rain. Their release amount was negatively correlated to the pH value of acid rains. In polluted red soil and yellow red soil, Cd existed mainly in exchangeable form, and Cu in organically bound and Mn oxide-occluded forms. Zn existed mainly in residual and exchangeable forms in polluted red soil, and in residual and organically bound forms in polluted yellow red soil. To some extents, the release of Cd, Cu and Zn and the chemical forms of Cd and Zn in test soils were affected by soil organic matter content and CEC. The release amount of bio-available Cd and Cu in polluted red soil and yellow red soil was increased greatly with the increasing acidity of simulated acid rains, but the transformation of Zn from stable to bio-available form was not obvious.