Screening And Application Effect Of Organic-inorganic Passivation Remediation Of Heavay Metal Cd

Food and food safety problems caused by soil pollution are worrying.Soil heavy metal pollution is relatively serious,so soil remediation needs to be solved urgently.At present,passivation remediation has become an important way of remediation of heavy metal contaminated soil in farmland.In this paper,several kinds of straw and cattle manure materials were utilized as resources.A series of studies on the passivation and remediation effects of organic-inorganic composite passivation materials on heavy metals(Cd)in soil were carried out,and a soil heavy metal(Cd)organic-inorganic composite passivator with dual functions of remediation of heavy metals(Cd)Contaminated Farmland and improvement of fertilizer soil was developed.In this paper,five kinds of inorganic passivation materials(lime,manganese dioxide,bentonite,attapulgite,calcium magnesium phosphate fertilizer)and other five kinds of organic passivation materials(cattle manure organic fertilizer,cattle manure biochar,straw ash,straw biochar,humic acid)were incubated with either single or organic-inorganic compound at the different dosages.The experiments showed that the passivation efficiency of 4% and 8%cattle manure organic fertilizer,4% and 8% attapulgite,4% and 8%calcium magnesium phosphate(Ca-Mg-P)fertilizer,4% and 8%bentonite,and 4% attapulgite + 4% cattle manure organic fertilizer,8%attapulgite + 8% cattle manure organic fertilizer,4% calcium magnesium phosphate fertilizer + 4% cattle manure organic fertilizer were all over50%.Cattle manure organic fertilizer,Ca-Mg-P fertilizer,attapulgite and bentonite were selected for pot experiment.The soil available Cd content in treatments of Ca-Mg-P fertilizer decreased significantly compared with the control,among which Ca-Mg-P fertilizer had the better passivation effect at 8% than 4% application rates.The combined passivation materials of cow manure organic fertilizer + attapulgite,cow manure organic fertilizer + Ca-Mg-P fertilizer,cow manure organic fertilizer +bentonite had the better passivation effect.Additionally,all passivation treatments in the different combinations significantly reduced the content of available Cd in soil.The passivation effect of the combination of Ca-Mg-P fertilizer and cattle manure organic fertilizer was the best among all treatments.Therefore,the ratio of cattle manure organic fertilizer and Ca-Mg-P fertilizer could be determined according to the maximum proportion.