Comparison of remediation effects of different passivators on cadmium-contaminated rice paddy
Cadmium pollution in soil brings a serious threat to food security and human health,and the problem of cadmium pollution in paddy fields is a priority for heavy metal pollution and prevention in soil.Pot experiments were conducted to screen suitable cadmium passivators for soil remediation in farm-land.10 passivators including T1(anomaterials,etc.),T2(lime),T3(oyster shells,etc.),T4(CaO),T5(silica-calcium fertilizers),T6(organic fertilizers of goat dung),T7(Bacillus cereus,etc.),T8(or-ganic fertilizers of pig manure),T9(oyster shells),and T10(microorganisms,etc.)were used to com-pare the remediation effect of 10 passivators on cadmium contaminated rice paddy and the growth of rice.The results showed that passivators increased the pH of soil in rice paddy and altered the form of cadmium stored in the soil.The content of exchangeable cadmium in the soil treated with each passivator decreased by 4.6%to 44.8%compared to the control,with significant decrease in T8(44.8%),T6(36%),T1(31.15%),and T10(28.4%).The content of carbonate bound states increased.The changes in the content of Fe-Mn oxide-bound state and organic matter bound state were not significant.The proportion of residual cadmium showed an overall upward trend,with T6 having the largest increase,increasing by 53.85%com-pared to that of the control.The biomass of rice seeds treated with various passivators increased by 5.75%to 25.30%.The content of cadmium in the seeds,husks,and straw of rice was in the decreasing order of straw>grain>husk.The content of cadmium in the rice seeds ranged from 0.068 to 0.254 mg/kg,with T2(0.152 mg/kg),T5(0.143 mg/kg),T6(0.088 mg/kg),T7(0.126 mg/kg),T8(0.072 mg/kg),T9(0.068 mg/kg),and T10(0.071 mg/kg)being lower than the national limit standard(0.2 mg/kg).The content of cadmium in rice seeds of T6,T8,T9,and T10 significantly decreased by 61.90%,68.83%,70.56%,and 69.26%,respectively,compared to that of the control.T2,T6,and T8 had better effects of passivation based on analyzing the transformation of cadmium form in soil,rice biomass,and the content of cadmium in rice seeds.
cadmium pollutionpassivationsoil remediationthe form of cadmiumrice
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