模拟酸雨下铬污染土壤中Cr、Zn、Cu的释放特征

通过对对照土壤和铬污染土壤的模拟酸雨土柱淋溶试验,研究了模拟酸雨作用下土壤中重金属Cr、Zn、Cu的释放特征,比较了对照土壤与铬污染土壤重金属释放特征的差异.结果表明,模拟酸雨pH值越低,3种重金属的释放量越大；两种土壤中3种重金属对酸雨的敏感性差异为Cr ＞Zn＞ Cu,对照土壤对重金属吸附能力为Cu＞ Zn,铬污染土壤对重金属吸附能力为Zn(≥)Cr＞Cu,说明金属Cr对土壤中Cu、Zn的吸附能力有一定的影响作用；土壤中Cu与Zn的累积释放量之间均存在着显著的线性关系,而在铬污染土壤中Cu与Cr的累积释放量之间呈现显著指数关系；在pH4、pH5的模拟酸雨作用下土壤中释放的Cr年平均浓度分别超标127、104倍,酸雨加速了铬污染土壤中Cr的释放,从而增加了环境中Cr对人类直接或潜在的危害性.

Desorptive Behavior of Cr, Zn,Cu species in the Chromate-polluted Soil Based on Simulated Acid-Rain Pattern

Desorptive behavior of Cr, Zn, Cu species in chromate-polluted soil was studied by contrasting normal soil with the chromate-polluted soil on basis of simulated acid-rain derived from column shower, and the desorptive difference between the two soils was presented. The experiments showed that the large desorptive quantities of the said heavy metals were comparable to low pH value of the simulated acid-rain, the sensitive difference of the two soils for the said heavy metals increased in order of Cr>Zn>Cu, whereas adsorption capacity of contrasting soil to the said heavy metals increased in order of Cu>Zn; the adsorptive capacity of chromte-polluted soil to the said heavy metals increased in the order of Zn>>Cr>Cu. It was concluded that the occurrence of chromate in the said soil had a specific effect on adsorption of Cu, Zn heavy metals, and that distinct linear correlation occurred in accumulative desorptive behavior for Cu, Zn species in both soils, and that accumulative desorptive quantities for the Cu, Cr species increased exponentially. The annual mean desorptive chromium-species quantities form the said soils were 127 and 104 times as much as those of National Standard at pH=4 and pH=5, respectively, i.e., the acid-rain accelerated the desorptive chromium species in chromate-polluted soil, therefore more potentially hazardous effect of chromium species was developed directly or indirectly.