Spatial and temporal distribution of the microbial community structure in the receiving rivers of the middle and lower reaches of the Yangtze River under the influence of different wastewater types

The gradual intensification of human activity has caused severe negative impacts on the ecosystems of the Yangtze River Basin. Treated effluents still affect the environment and health of receiving rivers, particularly in terms of microbial community structure. However, relatively few studies have been conducted on the differences in the effects of wastewater types on microbial community structure. Three sampling campaigns (237 samples) were conducted in the Nanjing and Wuhan sections of the Yangtze River Basin. Our results showed that the microbial community structure differed significantly among the water periods and could recover to its original state at > 500 m downstream of the outfall. The diversity of the receiving rivers under the influence of industrial wastewater was higher than that of the other wastewater types, although the number of taxa was lower than that of other wastewater types. Cyanobium_PCC-6307 and Rhodoferax were screened for biomarkers in samples affected by domestic and industrial wastewater, respectively. Although different kinds of wastewater influenced the microbial community structure, environmental factors, and geographical distance were still the main drivers. This study suggests that treated wastewater still poses a risk to ecosystems and highlights the importance of effective management strategies for assessing ecosystem health.