Activation Mechanisms And Application Of Biochar On Arsenic In Soil

As an alkaline amendment,biochars,because of its special structure,can reduce the amount of arsenic adsorbed by soil particle and promote the available arsenic in soil under specified conditions.It is a great challenge for remediation of arsenic-contaminated soil.In this study,we prepared vinegar residue as raw materials to burned for biochar.Soil anaerobic incubation experiment,pot experiment and field test were carried out to investigate the activation effect of biochar and to verify its validity.The results were as follows:(1)Soil anaerobic incubation with vinegar residue biochar(VB)was conducted.Combined with three-dimension excitation emission matrix fluorescence spectroscopy(3D-EEM)to analyze DOM composition in liquid phase and species abundance in the microbial community structure,the effect of VB on reduction and release process of arsenic in soil by was investigated.The results showed that almost all of As(V)was reduced to As(III)in culture system,and concentration of dissolved As presented as VB-300>VB-500>VB-700>CK.Three kinds of biochar increased the humification of DOM in culture system,and soluble microbial metabolites appeared in the VB-300 treatment.Result of high-throughput sequencing revealed that the abundance of As(V)-reducing strains such as Anaeromyxobacter,Clostridium,and Desulfosporosinus were significantly increased in biochar culture system,and there were most key species in VB-300 treatment.(2)Pot experiments Vetiveria zizanioides were conducted.Effect of biochar application and different water management to phytoremediation of As-contaminated soil was observed by growth,antioxidant system,arsenic content and arsenic extraction of vetiver.The results show that the biomass of vetiver decreased with the increase of biochar application;Antioxidant enzyme activities of vetiver were significantly higher than CK,which indicated vetiver can effectively remove H2O2 and free radicals to ensure its normal growth;Biochar and moisture can promote As absorption of vetiver,and 1%application and 150%of FC(field capacity)presented the best,reaching 23.73 ?g.(3)In order to verify the effect of enhance phytoremediation of arsenic by biochar,field experiments was carried out based on the above research results.The results showed that intercropping with Pisum sativum L.could increase arsenic accumulation in above-ground of Sedum plumbizincicola,and increased the biomass of the sedum;Biochar significantly increased the biomass and yield of Pisum sativum L.;Biochar and intercropping could promote the accumulation of As in sedum;As of pea roots and leaves was increased by applying biochar,and As concentration in Pisum sativum L.various parts presented as root>leaf>stem>fruit.After the application of biochar,available As concentration in soil increased significantly,about 15.60%,which could promote the phytoremediation of arsenic lightly polluted soil.