Spatial Distribution Characteristics Of Bacterial Communities And Environmental Drivers In Bosten Lake

Bosten Lake is located in the southeast ofYanqi Basin,Xinjiang Uygur Autonomous Region,China.It is the only inland saltwater lake in the arid and semi-arid regions of northwest China and plays an important role in the surrounding terrestrial ecosystem.However,due to its climate environment,geographical location and special ecosystem environment,coupled with the increasingly serious water pollution problems in recent years,people are paying more and more attention to the environmental problems of Bosten Lake.Bacteria in lakes are the key driving force for the ecological geochemical cycle in lake water ecosystems.Changes in the composition and species of bacterial populations can be used to reflect changes in lake water environment.In this study,the water body and sediment of Bosten Lake were taken as the research object.By analyzing the evolution trend of the hydrological situation of Bosten Lake since the 1960 s,combined with the current situation of water environment pollution in the Great Lakes,the variation characteristics and influencing factors of the water environment of Bosten Lake were clarified.The microbial quantity,community composition and diversity of water quality and sediment in the lake area were determined by fluorescence quantitative PCR and high-throughput sequencing technology.The response relationship between bacterial community structure and environmental factors in Bosten Lake was analyzed,which provided a basic reference for the protection and sustainable development of the ecological environment of Bosten Lake.Based on the studies conducted,the following main conclusions were drawn:(1)Data collection,field sampling and indoor experimental analysis were used to analyse the hydrological situation of Bosten Lake and the distribution characteristics of pollution in the water environment.The results show that the main inlet flow recharge in the Bosten Lake area is the East Branch of Baolang Sumu,with a multi-year average inlet runoff of about 2.017 billion cubic metres,showing a gradual upward trend in the last decade;The outflow of water from the lake is mainly from the pumping station,with a multi-year average outflow of about 860 million cubic metres,and the flow in and out of the lake is gradually increasing.The hydrochemical change of Bosten Lake changed from carbonate to Cl-+SO42-——Na++K+before the mid1950s.The order of main ion concentration in the Great Lakes was Cl->SO42->Na+>Mg2+>HCO3->Ca2+>CO32->K+.The water quality of the lake is generally poor in the western part of the lake close to the reed breeding area and better in the south-western part of the lake close to the pumping station.The various physico-chemical factors in the sediment respond to changes in pollutant concentrations in the water column,but the magnitude of change is small,but the magnitude of variation is small and largely shows higher concentrations in the north-western and eastern parts of the lake than in the south-western part of the lake.(2)An analysis of the structural changes of the bacterial community in the water column and sediment of Lake Bosten revealed that the abundance and species of bacterial distribution varied considerably in different habitats.The spatial variation in bacterial abundance in the water column was small,while the variation in bacterial abundance in the sediment with space was large.There are some differences in the bacterial community structure in the water and sediment of Bosten Lake at the spatial level.In the water body,the three dominant groups of Proteobacteria,Actinobacteria and Firmicutes were evenly distributed in each sample point.In the sediments,the distribution of bacterial groups in Bosten Lake was significantly different,but the dominant groups were relatively few.Proteobacteria,Firmicutes and Chloroflexi were the three dominant phyla,accounting for more than 75%of the total proportion.The distribution of bacteria in water and sediment of Bosten Lake is quite different from that of Chloroflexi,which is a unique dominant phylum in sediment.(3)By analyzing the correlation between bacterial abundance,structure composition,diversity and environmental factors in water and sediment of Bosten Lake,the results showed that the spatial distribution of bacterial abundance,community composition and diversity in Bosten Lake was affected by various environmental factors,and showed some differences due to different water environments.The key environmental factors affecting the bacterial richness of water are salinity and nitrate nitrogen,and the key environmental factors affecting the diversity of water are permanganate index and water depth.The key environmental factors affecting the abundance of bacteria in sediments were total phosphorus,ammonia nitrogen,total potassium and total carbon.The main environmental factors affecting bacterial diversity were dissolved organic carbon,ammonia nitrogen,pH,total nitrogen and organic matter.Most of the environmental factors will affect the structure of bacteria in water and sediment.RDA analysis of bacterial community and environmental variables showed that the change of bacterial community structure in Bosten Lake was affected by many environmental factors.Ammonia nitrogen and salinity were the key factors affecting the distribution of bacteria in water,and ammonia nitrogen was the key factor affecting the distribution of bacterial community in sediments.