pH和腐植酸对Cd,Cr在土壤中形态分布的影响

通过调节pH值和腐植酸(HA)的含量,并采用Tessier五步连续萃取法,研究了pH和腐植酸对土壤中重金属Cd和Cr形态和生物活性的影响.结果表明,随着pH的升高,Cd可交换态和碳酸盐结合态的含量变化互为消长,生物活性基本不变;其Fe/Mn氧化物结合态、有机结合态和残渣态的含量不变.Cr可交换态和碳酸盐结合态的含量随着pH的升高而升高,生物活性增强;有机结合态的含量减少,Fe/Mn氧化物结合态和残渣态的含量不变.随着腐植酸投加量的增多,Cd和Cr可交换态和碳酸盐结合态的含量迅速减小,生物活性减弱;它们的Fe/Mn氧化物结合态略增,有机结合态和残渣态含量基本不变.

Effects of pH and Humic Acid on the form Distribution of Cadmium, Chromium in the Soil

Effects of pH and humic acid on the form distribution of cadmium,chromium in the soil were studied by adjusting pH and humic acid(HA)content with the Tessier five steps of continuous extraction method.The results showed that the contents of exchangeable and carbonate bound form of cadmium changed each other and the biological activity of cadmium remained about the same with the increasing of pH.Besides the Fe-Mn oxide,organic,residual form of cadmium basically unchanged.The contents of exchangeable and carbonate bound form of chromium increased with the increasing of pH,which leaded to the biological activity enhancing.The content of organic form of chromium decreased but the contents of Fe-Mn oxide,residual form of chromium increased a little.The contents of exchangeable and carbonate boun-d form of cadmium and chromium decreased quickly,which meaned the reduced biological activity.The contents of Fe-Mn oxide form of them increased unconspicuously and the contents of organic and residual form of chromium were still in their original level.