Study On The Influence Factors Of Sediment Bacterial Community Structure On Methane Emission Of The Three Gorges Reservoir

In this study,quantitative PCR and high-throughput sequencing were used to analyze the species composition,diversity,RDA and phylogeny of bacteria and methanogenic bacteria communities in the water and sediment between the main stream and tributaries of the Three Gorges Reservoir Area in Wanzhou,Chongqing.Pearson correlation analysis and redundancy analysis of methane functional bacteria community and CH₄emission flux in sediments.the following research results are obtained:(1)There was no significant difference in the diversity and abundance of bacterial community in the main stream and tributary water and sediment;The number of species in the water body and sediment of the main stream and tributary has no obvious regularity,but the composition of bacterial community has certain similarity,and there are also their own unique species.Therefore,TOC,NH₄⁺-N content,water temperature and p H were the main factors that led to the diversity and abundance of bacterial community in May was significantly higher than that in other three months.Environmental factors affect the composition and structure of bacterial community by affecting the diversity and abundance of bacterial community.(2)On Phylum level,the bacteria species in the sediment are more than that in the water body as a whole,and there are several species with unique and relatively low abundance in the sediment,such as Ignavibacteria,Latescibacteria,etc.No matter in the main stream or tributary,proteus,actinomycetes and Bacteroides are the dominant species in fresh water and sediment,such as lakes and reservoirs.TOC and NH₄⁺-N are important environmental factors that affect the composition and structure of bacterial community in water and sediment.(3)There was no significant difference in the diversity and abundance of methane functional bacteria community in the main stream and tributary water and sediment,and there was no significant difference in species on Phylum level.The dominant methanogenic bacteria on Order level are Methanobacteriales,Methanomicrobiales and Methanosarcinales;the dominant methanogenic bacteria on Class level are ?-Proteobacteria and?-Proteobacteria.NH₄⁺-N,DO content and p H are important factors affecting the abundance of mcr A gene and pmo A gene.TOC is an important environmental factor affecting the community structure of methane functional bacteria in sediment.(4)In methanogenic community,some Archaea have great influence on methane emission,such as unclassified?f?Methanoregulaceae,unclaasified?p?Euryarchaeota,Methanospirillum,Methanoregula,Methanobacterium and Methanosarcinaceae,When the abundance of these species increases,methane emission will be affected by promoting methane production.In the methane oxidizing bacteria community,the key species that affect methane emission are Methylosarcina and Methylobacter.When the abundance of methyloctarcina and methylbacterium increases,methane oxidation will be accelerated and methane emission at the water gas interface will be reduced.