Effects of Different Passivating Agents on Cd Pollution in Alkaline Farmland Soil

Abstract

In this study, cadmium-polluted farmland in the southern suburbs of Jiaozuo, Henan Province was selected as the research object. Under the field conditions, two passivating agents such as aluminosilicate and calcium-aluminum hydrotalcite were added respectively, and the cadmium form content was analyzed by BCR extraction method. The passivating effect of different passivating agents on soil cadmium in alkaline farmland in northern China was studied under the application rate of 200 and 400kg/mu. The results showed that silicoaluminate and calcium-aluminum hydrotalcite reduced soil pH value in different degrees, but had little effect on soil pH value. The two passivating agents can convert the soluble Cd of weak acid to the residual Cd, and the transformation effect is more significant with the increase of the applied amount. The passivation effect is ranked as calcium aluminum hydrotalcite > silicaluminate, among which 400 kg/mu of calcium aluminum hydrotalcite has the most obvious passivation effect, and the effective content of Cd is reduced by 70.5% compared with group CK. In general, after the application of two passivators and different amounts, the soluble Cd content of weak acid in soil decreased significantly, the reducible Cd content decreased slightly, the oxidizable Cd content increased slightly, and the residual Cd content increased significantly.