Study On Microbial Community Structure And Nitrogen Metabolism In Suburban Rivers Of Plain Area

Water ecology protection and restoration is crucial for the future integrated water environment management.Microorganisms play an important role in the natural purification of water bodies and participate in the nitrogen transformation process,but there are still limited studies on the structural characteristics and nitrogen metabolism potential of river microbial communities under different spatial and temporal conditions.In this study,we analyzed the spatial and temporal variation of water quality factors in rivers of plain areas,and elucidated the influence of exogenous inputs on river water quality through source analysis model.We also investigated the spatial and temporal characteristics of nitrogen metabolic pathways and revealed the mechanism of nitrogen morphological transformation driven by river microorganisms.This study is of great theoretical value and practical significance for establishing robust ecological restoration goals for rivers in the plains and exploiting resources related to river nitrogen metabolism microorganisms.The main findings are as follows:（1）There are significant seasonal differences in the water quality of rivers in the plain area,mainly including environmental factors such as T、DO and p H;through monitoring,it is found that there is a certain degree of nitrogen pollution in the rivers in the plain area,and the source analysis results showed that the exogenous input was dominated by soil organic nitrogen,fertilizer and ammonia nitrogen from precipitation.（2）The composition and diversity of riverine microbial communities were significantly affected by spatial and temporal variation.The richness and diversity of microorganisms in rivers in wet seasons are significantly higher than those in dry seasons,which is mainly related to the rainfall of wet seasons bringing soil microorganisms into rivers;T、TN、NO₃^-and NH₄⁺are the key environmental factors affecting the microbial community structure of the river during the wet season,and p H and CODcr are the key environmental factors affecting the microbial community structure of the river during the dry season.（3）Seasonality is the key factor affecting the microbial drive of nitrogen metabolism and morphological transformation in rivers.T and p H are the environmental factors that mainly affect the nitrogen function of microorganisms in rivers.Among them,Dechloromonas and uncultured＿f＿Anaerolineaceae are the main dominant bacteria involved in the nitrogen transformation in the river during the wet season,hgcl＿clade,Sphingorhabdus and Limnohabitans are the main dominant bacteria in the dry season;in addition,the rivers in the wet season The increase in the abundance of nitrification functional genes leads to the accumulation of NO₃^-in rivers;the increase in the abundance of denitrification and nitrate reduction functional genes in rivers in dry seasons promotes to the conversion of NO₃^-to NO₂^-in rivers.