Study On The Remediation Of Arsenic-contaminated Soil By Penicillium Combined Biochar

Fungal remediation of arsenic-contaminated soil is considered to be an effective method to adsorb and solidify arsenic.The porous structure,high ion exchange capacity and abundant organic carbon content of biochar all indicate its status in soil remediation.To explore the effects of biochar and penicillium on the contaminated soil,in this paper,two arsenic-contaminated soils were selected,3×3 randomized block experiment(biochar gradients was 0%,2%,4%,penicillium gradients was 0%,10%,20%)were conducted,cultivate with different amounts of penicillium and biochar for the remediation of arsenic-contaminated soil.By measuring the concentrations of As(Ⅲ),As(Ⅴ)and total arsenic in the soil,the effects of the penicillium and biochar on the passivation rate of arsenic and the conversion of the valence state of arsenic in the arsenic-contaminated soil were investigated.Meanwhile,the relationship between the indicators of microorganisms and the effective arsenic content was established through the analysis of the floristic analysis and Biolog method.The experimental results show that in the environment polluted by low effective arsenic,the total arsenic content in soil did not change with the increase of the applied amount of penicillium and biochar,the passivation rate of efiective arsenic reached up to 27.6%.But in the environment polluted by high effective arsenic,the passivation rate of effective arsenic could only reach up to 15%.However,there was no conversion between the two valence of arsenic(As(Ⅲ),As(Ⅴ)),As(Ⅴ)was fixed by penicillium and biochar,but the content of As(Ⅲ)in soil remained unchanged basically.While the effective arsenic content decreased,the content of actinomycetes in soil remained basically the same,but the total amount of bacteria in soil increased.The addition of penicillium and biochar changed the functional diversity of microbial community in soil.The microbial community functional diversity and carbon source utilization richness in soil showed a trend of increasing first and then decreasing with the increase of biochar concentration gradient in the environment polluted by low available arsenic,but only showed a trend of decreasing in the environment polluted by high available arsenic.The effects of high inoculum(20%)and low inoculation(10%)on the functional diversity of microbial communities in arsenic-contaminated soils were not significantly different.The highest soil microbial community functional diversity,species richness,carbon source abundance and utilization capacity were observed in the treatment of 2%biochar and 10%of penicillium.Penicillium has a weak ability to utilize amines and a small number of acid carbon sources(AWCD<0.5),has high metabolism capacity for most carbon sources and lipid carbon sources in amino acids(AWCD>1.0),has slightly weaker metabolism capacity for sugars and phenolic acid(AWCD=0.3～1.0).Penicillium had the highest utilization rate of D-galacturonic acid,L-asparaginic acid,L-serine,L-arginine and R-hydroxybutyric acid(AWCD>1.2).Studies have shown that:In the environment polluted by low available arsenic,Low concentration of biochar increased the metabolic activity and functional diversity of microorganisms,however,the inhibited effects occurred when the biochar content increased.But In highly effective arsenic contaminated environment,the addition of biochar can only inhibit soil microbial community diversity.The addition of penicillium to arsenic-contaminated soil can significantly increase the functional diversity of microbial communities and improve the microbiota community structure in arsenic-contaminated soil.The dominant carbon source of Penicillium is mostly the secretion of plant rhizosphere,which provides a reference for the remediation of arsenic-contaminated soil using the combination of penicillium and plants.the combined remediation of penicillium and biochar could reduce the content of effective arsenic,improve the microbial environment in the arsenic-contaminated soil,and show good remediation performance to the arsenic-contaminated soil.