Effects Of Dairy Dung Biochar On Heavy Metal And DDT Bioavailability In Soil

In order to explore the effect of biochar,which is prepared with dairy dung as raw material,on the bioavailability in soils contaminated with heavy metal Cd,Cu,Cr and DDT,this paper utilizes pot experiments,based on the study of the effect of cow dung biochar prepared at high and low temperatures on the remediation of heavy metals Cd,Cu,Cr and DDT in soil,and the effects of biological carbon on the bioavailability of DDT and the evaluation method of DDT bioavailability were studied.Specific results were as follows:(1)The study on the remediation effect of biochar from dairy dung on heavy metals in soil showed that,the addition of dairy dung biochar could improve the pH value of soil,and had good passivation to heavy metals Cd,Cu and Cr,and the biochar of dairy dung at 700 ? was better than 300 ?.With the increase of biochar content,the pH value of soil gradually increased,and the passivation effect was better.When the dosage of dairy dung biochar prepared at 700? at 10g·kg-1,compared with the control,Cd,Cu and Cr contaminated soil pH value were increased by 0.2,0.7,0.7;Cd?Cu and Cr were passivated content increased by 42.2%,36.5%,21.0%,respectively.(2)Effect of dairy dung biochar on bioavailability of heavy metals in soils.The results showed that the addition of dairy dung biochar could decrease the extractable content of Cd,Cu and Cr in the soil,increase the residues content of Cd,Cu and Cr,and decrease the root and leaf system of brassica chinensis,and 700? is better than 300?.When the dosage of dairy manure biochar prepared at 700? at 10g·kg-1,compared with the control,the content of acid-exchangeable fraction of Cd,Cu and Cr in contaminated soil are decreased by 22.9%,40%,21.7%;the content of residual fraction are increased by 77.7%,41.4%,64.9%;the contents of Cd,Cu and Cr in the leaves and roots of the brassica chinensis were reduced by 71.5%,38.1%,50% and 60%,62.2%,26.9%,respectively.The contents of Cd,Cu and Cr in leaves and roots of brassica chinensis were all significant positively correlated with the content of acid extractable,and the contents of residues were negatively correlated.(3)The study on the remediation effect of biochar on DDT pollution in soil shows that the biodegradation of DDT in soil was enhanced by addition of dairy dung biochar,and the degradation effect was enhanced with the addition of biochar,and 300 ? is better than 700 ?.When the dosage of dairy dung biochar prepared at 700? at 10g·kg-1,compared with the control,the content of DDT in soil decreased by 35.3%.The effect of biochar on the aging residue was also studied.With the aging time,the content of DDT in the soil decreased,and the content of DDT in soil decreased more obviously when dairy dung biochar was added.(4)The DDT content in soil extracted from n-hexane can effectively evaluate the bioavailability of DDT in soil.Adding dairy dung biochar to reduce the DDT bioavailability in soil and inhibit the absorption of DDT in the roots and leaves of brassica chinensis,and 700 ? is better than 300 ?.When the dosage of dairy manure biochar prepared at 700? at 10g·kg-1,compared with the control,the content of DDT in the soil extracted by n-hexane decreased by 17.3%,the content of DDT in roots and leaves of brassica chinensis decreased by 63.8% and 39.7%,respectively.