Study On Microbial Diversity And Distribution Characteristics Of Sediments In The Lake Gehu

The Lake Gehu is the second largest lake in the Lake Taihu Basin.As an important economic development and ecological protection area in the Lake Taihu Basin,it plays an important role in the regulation of water quantity and water quality.In recent years,with the continuous increase of human activities in the area of the Lake Gehu,the decline in water environment quality of the lake has led to huge changes in the ecological environment of the Lake Gehu.As an important part of the ecological environment,microorganisms play an irreplaceable role in material circulation and ecological regulation.Meanwhile,the ecological environment also affects the microbial community at all times.Therefore,studying the distribution characteristics of the water quality,microbial community structure and evaluating the ecological status has significant reference for the environmental management and pollution control of the Lake Gehu.In this study,in the four quarters of 2018,samples of water and sediments from the Lake Gehu and typical pollution sources around the lake area were collected.According to the analysis results of the water quality parameters of the Lake Gehu in the study,the distribution characteristics of the water quality parameters were discussed,and the water environment quality status of the Lake Gehu was understood through the comprehensive water quality evaluation.At the same time,the high-throughput sequencing method was used to investigate the distribution characteristics of microbial diversity in the surface sediments in the Lake Gehu,and the cause of the microbial community change was preliminarily determined by the correlation analysis between water quality parameters and microbial community.On this basis,combined with the characteristics of the microbial community structure of typical pollution sources around the lake,machine learning methods was used to carry out a source tracing on the influences of the microbial diversity in the Lake Gehu.The research results could provide scientific basis and theoretical reference for the water environment management of the lake.According to the distribution characteristics of water quality parameters in Lake Gehu,the water quality parameters exhibited more obvious seasonal and spatial distribution characteristics.The parameters such as nutrients and organic pollution indicators were higher in summer,while the heavy metals show obvious spatial distribution characteristics.concentrated in the northern and southwestern regions of the lake.The water quality evaluation results showed that the water quality of the Lake Gehu basically reached the ? level of water standards.The samples that failed to meet the ? level of water standards were concentrated in the western and southeastern parts of the Lake in the summer.The pressure for achieving the standard mainly came from TP,TN and COD.To further study the health of ecology,high-throughput sequencing method was used to study the microbial community structure of the Lake Gehu and typical pollution sources around the lake.The results of microbial diversity index analysis showed that the microbial diversity and species richness of lake were greater than those of typical pollution sources.Species composition analysis showed that there were large differences in each taxonomic levels.The dominant bacteria phylum in the microbial community structure of lake sediments were Proteobacteria,Chloroflexi and Acfinobacteria,etc.The results of microbial diversity analysis showed that the microbial communities had significant differences between winter and other seasons in the lake,while the autumn samples were highly similar to the summer.The dominant bacteria phylum in Urban wastewater treatment plant(UWTP)were Proteobacteria,Bacteroidetes and Firmicutes etc.and the differences in the microbial community structure of different UWTP varied according to the type of wastewater.The dominant bacteria phylum in aquaculture farms were Acfinobacteria,Proteobacteria and Bacteroidetes,etc.,and the microbial community structure varied according to the production cycle.The prediction results of functional genes based on high-throughput sequencing showed that the microbial community of the Lake Gehu was greatly affected by UWTP in winter and aquaculture in spring.On this basis,the correlation analysis between water quality parameters and microbial population diversity was determined.The results showed that the microbial diversity and species richness in the sediments of the lake were significantly positively correlated with TN and negatively correlated with TP,and the typical pollution source had a certain degree of influence on the microbial community in the sediments of the lake.The machine learning models SourceTracker and FEAST were used to further analyze the impact degree of typical pollution sources on the microbial community in the lake.The analysis results of the two models showed a high similarity,of which the SourceTracker had a higher interpretation rate,and the recognition on the impact degree of the trace level was better than FEAST,while the FEAST had a higher resolution for unknown sources and could be used to judge potential pollution sources.Therefore,the combination of the two models could effectively improve the accuracy of source resolution.Correlation analysis and machine learning model analysis results showed that the microbial community in the northern region of the lake was greatly affected by municipal sewage in winter,while the southern area was greatly affected by aquaculture in spring.In addition,aquaculture and algae growth might have a joint influence in summer and autumn.