Regulation Of Arsenic Content And Valence Of Indigenous Microorganisms Under Different Oxygen Conditions

Microorganisms play an important role in the transformation of arsenic.There are abundant microbial resources in soil,and different soil environments have different microbial communities.In order to explore the influence of indigenous microorganisms on arsenic conversion under different oxygen-containing conditions,this experiment set aerobic and anaerobic conditions,with arsenic migration and conversion as the center,soil microbes as the main regulatory factors,and chemical analysis and molecular biology as the research methods,to explore the arsenic transfer and conversion in arsenic-contaminated soil in mining areas.The main conclusions of this paper are as follows:(1)Under aerobic conditions,the content of water-soluble arsenic increased,the content of humus arsenic decreased,and the content of other forms of arsenic remained basically unchanged.Compared with the non-bioactive soil samples,the available arsenic content in the non-sterilized soil was higher,and microorganisms played a leading role in the conversion of arsenic,increasing the availability of arsenic.The water-soluble arsenic was mainly As(V),and the exchangeable arsenic was mainly As(III).(2)Under anaerobic conditions,the content of water-soluble arsenic,exchangeable arsenic,carbonate-bound arsenic and humus bound arsenic in non-sterilized soil increased,the content of Fe-Mn oxide bound arsenic,strong organic matter bound arsenic and residual arsenic decreased,and the refractory arsenic was converted to the soluble arsenic.Compared with abiotic soil samples,the content of bioavailable arsenic is high,and microorganisms play a leading role in arsenic conversion to increase the availability of arsenic.The water-soluble arsenic is mainly As(III),and the exchangeable arsenic is also mainly As(III).(3)Under aerobic and anaerobic conditions,the soil microbial community structure is significantly different.Under aerobic conditions,soil microbes were mainly distributed in Proteobacteria ? Acidobacteria ? Actinobacteria.Soil microorganisms mainly consist of Unidentified?Clostridiales and Sporolactobacillus,while Sporolactobacillus was one of arsenic oxidizing bacteria.The expression of oxidizing genes aio A increased,while that of reducing genes ars C and arr A decreased.Under anaerobic conditions,soil microbes were mainly distributed in Firmicutes?Proteobacteria?Acidobacteria.The bacterial were mainly Unidentified?Clostridiales and Sporolactobacillus.The expression of aio A decreased,while that of ars C and arr A increased.It was found that under aerobic conditions,soil contains both arsenic-oxidizing bacteria and arsenic-reducing bacteria.Under microbial action,soil water-soluble arsenic content increases,the expression of arsenic-oxidizing genes is stronger than that of arsenic-reducing genes,and soil water-soluble arsenic is mainly As(V).Under anaerobic conditions,arsenic-reducing bacteria in soil are dominant,promoting the conversion of non-biological available arsenic to biological available arsenic.The expression of arsenic-reducing genes is stronger than that of arsenic-oxidizing genes,and soil water-soluble arsenic is reduced to As(III).Compared with aerobic conditions,soil arsenic is more effective and toxic under anaerobic conditions.It provides theoretical basis for arsenic removal and remediation and potential secondary pollution evaluation in arsenic-contaminated soil.