Stability Study of Four Passivators for Remediation of Cadmium-Contaminated Rice Fields
In order to investigate the remediation effect and stability of four passivators on cadmium-contaminated paddy fields,a field experiment was carried out in Garden Village,Yanxi Township,Liuyang City,with Yuzhenxiang and Xiang-wanxian No.13 as the test varieties of paddy fields,and four passivators,namely,calcium sulphoaluminate(S),calcium chloroaluminate(L),calcium-aluminium hydrotalcite(A),magnesium-aluminium hydrotalcite(B)were used to investi-gate the effects of the passivators on the yields of the different varieties of paddy fields and on the cadmium uptake of dif-ferent varieties of paddy fields at the third year of the application period.The results showed that,compared with CK,the effective Cd content of soil decreased by 27.78%and 19.44%in L and B treatments,respectively.Meanwhile,the treat-ments significantly reduced the activation rate of soil Cd.The Cd content of Yuzhenxiang and Xiangwanxian No.13 brown rice in A treatment was the lowest among all the treatments,which decreased by 48.89%and 51.52%,respectively,com-pared with the control,and decreased by 20.00%and 21.21%in L treatment,and 40.00%and 12.12%in B treatment,respectively.Application of passivation had no significant effect on the yield of Xiangwanxian No.13,L and S treatments significantly increased the dry matter of stems and leaves,A treatment had no significant effect on the dry matter of stems and leaves,and B treatment significantly increased the dry matter of the stems and leaves of Xiangwanxian No.13,but sig-nificantly reduced the dry matter of the stems and leaves of Yuzhenxiang.Taken together,one-time application of calcium-aluminum hydrotalcite has the best stability for remediation of cadmium-contaminated soil and reduction of cadmium in rice.The effect of calcium sulfoaluminate is relatively poor.
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