RESPONSE OF MICROORGANISMS IN SURFACE SEDIMENTS TO TAIL-WATER DISCHARGE FROM SEWAGE TREATMENT PLANT IN PLATEAU CITY RIVERS DURING DRY SEASON

The response of sediment microbial communities of seven urban and rural rivers to wastewater from sewage treatment plants was analyzed by high-throughput sequencing technology in the upstream and downstream of main cities and towns in Nyingchi City, Tibet Autonomous Region.In the dry season, 14 sampling were collected from the upstream and downstream reaches of 7 towns, and the monitoring results of physical and chemical indices of water quality all reached the Class II standard of Environmental quality standards for surface water (GB 3838-2002, China) except Total Nitrogen; the diversity and richness of microbial community of the 14 sampling sites in Zayü River, Parlung Zangbo, Niyang River and the main stream of Yarlung Zangbo River were all lower than those in other regions, and there were significant differences between the main stream and tributaries of Yarlung Zangbo River; the dominant bacteria in surface sediment were Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes and Frimicutes, with a relative abundance of 77.87%-98.51%, the sum of the relative abundances of the top ten bacterial genera at the genus level was between 18.68 percent and 88.71 percent, its representativeness of collinearity analysis was very strong.The analysis of sediment microbial diversity and influencing factors showed that, dissolved oxygen (DO), the east longtitude (E), total phosphorus (TP), ammonia nitrogen content index (NH3-N) and total nitrogen (TN) had great influence.The functional proteins, dominant enzymes, and FAPROTAX function prediction also proved that the above indices influence different rivers in the plateau habitat as well.The domestic wastewater discharged from the sewage treatment plant had an impact on the microbial community diversity in the surface sediments at the sampling sites.