以西安市皂河为例，采用 16S?rRNA 测序技术等生物信息学分析手段，解析城市河流沉积物微生物群落对污 水处理厂排放的响应规律。结果表明：变形菌为皂河的优势关键物种；皂河群落的丰富度和多样性随着排污的汇 入逐渐降低，受西安市第二污水处理厂排放影响的中游河段与其他河段的差异性较为显著，标志物种为衣原体 （chlamydiae），不同河段间微生物群落结构改变会进而导致功能差异；亚硝态氮和温度是影响最显著的环境因子， 受西安市第九污水处理厂排放影响的河段与磷元素呈正相关，而受西安市第二污水处理厂排放影响的河段与氮 元素呈正相关。综上，污水处理厂排放影响下河流水质的变化对纳污河流沉积物微生物群落结构和功能会产生 一定影响，其中沉积物与上覆水之间污染物的季节性迁移转化规律还需更进一步研究。

Wastewater discharged from sewage treatment plants (STPs) may affect the structure and function of microbial communities in the sediment of receiving water body. The response of sediment microbial community in Zao River (Xi′an, China) to STPs discharge was investigated by 16S rRNA sequencing technology and bioinformatic analysis. The results revealed that Proteobacteria , Cyanobacteria , Bacteroides , Firmicutes , Actinobacteria , Chloroflexi and Acidobacteria were the dominant communities in the sediments of Zao River. The obtained sparse curve and species accumulation curve indicated that the sequencing depth and the number of samples were enough to reflect the changes in microbial community richness. The richness and diversity of Zao River community decreased gradually with the inflow of sewage. The difference in microbial community structure between the reaches near the 2nd STP sewage outlet and other river reaches was significant with the marker species being chlamydia . Furthermore, the metabolic pathways enriched in the up-middle-down reaches of the 2nd STP sewage outlet were photosynthesis in energy metabolism (ko00196), bibrio cholerae infection (ko05110), and the biosynthesis of secondary bile acids (ko00121), respectively. In general, nitrite nitrogen and temperature were the most significant environmental factors, accounting for 40.3% of the changes in the whole community. Proteobacteria was positively correlated with salinity, total phosphorus, COD, and pH, and negatively correlated with temperature, total nitrogen and ammonia-nitrogen. Likewise, cyanobacteria was primarily positively correlated with temperature and redox potential, and negatively correlated with pH, nitrate-nitrogen, and total phosphorus. In particular, the microbial communities near 2nd and 9th STP sewage outlets were determined by phosphorus and nitrogen levels, respectively. In conclusion, the altered microbial community structure in the sediments of sewage-receiving rivers can reflect the fluctuation in river water quality and the health of aquatic ecosystems influenced by sewage discharge.