[Structural Characteristics of Microbial Communities in the Sediments of the Niyang River in Tibet].

The Niyang River is an important tributary of the Yarlong Zangbo River, which is also an important water source in the Gongbujiangda and Linzhi areas of Tibet. In this study, water and sediment samples from 18 sites in the Niyang River were collected. The physical and chemical properties, concentrations of 12 heavy metals, and the microbial community in the sediments were determined. The microbial community structures in the sediments collected in 2017 and 2018 were highly similar at the phylum and genus levels. The most dominant type of bacteria in the sediment of the Niyang River was Proteobacteria. Other dominant bacteria included Bacteroidetes, Acidbacteria, and Actinobacteria. At the genus level, the abundance of was high. Other conditional pathogenic bacteria, such as and , were detected. Cluster analysis found that there were certain spatial differences among the upstream, midstream, and downstream microbial communities. The microbial community of sediments in the power station reservoir area was unique. Correlation analysis showed that the temperature, dissolved oxygen, electrical conductance, Cr, Zn, Sr, and Ba in the sediments had high correlation with abundance of specific microbes at the phylum level. Redundancy analysis suggested that total nitrogen, total phosphorus, dissolved oxygen, Cr, Sr, Ba, and Mn were the main influencing factors of microbial community structure in the sediments of the Niyang River. The results of this study provide data support for understanding the spatial and temporal distribution of the microbial community in sediments of the Niyang River and identifying their environmental impact factors.