Effects of Acid Mine Drainage on Physicochemical Factors and Nitrogen-fixing Microorganisms in the Root Zone of Mature Rice
[Objective]Acid mine drainage(AMD)is a kind of wastewater with low pH,high sulfate concentration and heavy metal enrichment.This study is aimed to investigate the abundance and composition of azotobacter community in the root zone of rice at mature stage and its response to AMD,and to elucidate the main driving factors of the change of soil azotobacter community structure.[Method]Rice pot experiment was carried out on paddy soil contaminated and uncontaminated by AMD from Tongling mining area of Anhui province,and three different treatments were set up(A:AMD irrigated contaminated soil;B:clean water irrigated contaminated soil;CK:clean water irrigated uncontaminated soil),nifH gene high-throughput sequencing technology was used to analyze the characteristics of azotobacter community in rice root zone soil under different treatments.[Result]The contents of SO42-,NO3-and heavy metals in rice root zone soil increased significantly,the soil acidified,and the diversity of azotobacter community decreased.The dominant nitrogen-fixing bacteria in rice root zone soil included Anaeromyxobacter,Geobacter,etc.The number of nitrogen-fixing bacteria enriched in CK treatment was significantly higher than that in A and B treatments,and Verrucomicrobia were mainly enriched in B treatment,while Proteobacteria were mainly enriched in CK treatment.pH、Cu、Pb and Zn were the main factors driving the community structure of azotobacter in rice root zone.Desulfovibrio and Desulfurivibrio with sulfur reduction function have significantly contributed to the change in nitrogen.[Conclusion]AMD had significant effects on soil chemistry and azotobacter in the root zone of rice,and restoring clean water irrigation promoted the recovery of azotobacter.The above findings provide new insights and ideas for biological remediation of AMD-contaminated soil.
AMDrice root zone soilroot zone nitrogen-fixing microorganismnitrogenheavy metal
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