酸雨中SO_4^(2-)、NO_3^-、Ca^(2+)、NH_4^+对红壤中重金属的影响

Effects of SO_4^(2-)、NO_3^-、Ca^(2+)and NH_4^+of acid rain on the heavy metals in red soils

在实验室条件下连续浸泡污染红壤和黄红壤,研究模拟酸雨中阴离子、阳离子浓度对土壤中重金属解吸行为和化学形态分布的影响.结果表明,酸雨加速了土壤酸化,重金属活性增强.增加模拟酸雨中SO42-、NO3-或Ca2+、NH4+浓度对Cd、Zn解吸行为均产生明显促进作用,但对Cu影响不明显.增加模拟酸雨中SO42-、NO3-浓度,红壤和黄红壤交换态Cd、Zn百分率明显降低,交换态Cr百分率明显增加,交换态Cu百分率稍有提高,交换态Pb百分率变化不明显;增加模拟酸雨中Ca2+、NH4+浓度,红壤和黄红壤交换态Cd、Cu、Zn百分率明显降低,交换态Cr和活性形态Pb明显增加,但Cu的化学形态分布主要受模拟酸雨pH值的影响.

Under the condition of laboratory, the desorption and chemical fractions of heavy metals in contiguouslysoak-contaminated red soil and yellow red soil by concentration of anion or cation of simulated acid rain were studied. The results showed that acid rain accelerated the soil acidification and strengthened in the activity of heavy metals. Increasing the concentration of SO42-, NO3-, or Ca2+, NH4+ in the acid rain would increase the desorption of Cd and Zn from soil; but not significant for Cu. Increasing the concentration of SO42- and NO3- in the acid rain, the ratio ofexchangeable Cd and Zn decreased, markedly, while the ratio of exchangeable Cr increased significantly; but the ratio of exchangeable Cu increased only a little and the ratio of exchangeable Pb transformed not significantly. Increasing the concentration of Ca2+ and NH4+ in the acid rain, the ratio of exchangeable Cd, Cu and Zn in the soil decreasedsignificantly, while the active Pb and exchangeable Cr increased significantly. However, the chemical fraction of Cu was mainly affected by pH values of the acid rain.