Reclaimed water-receiving rivers face increased hypoxic and malodorous risks after stormwater runoff. To investigate how initial runoff drives the co-variation of pollutants and microbial communities at the sediment–water interface (SWI), this study constructed a four-channel simulated river system based on the Froude similarity criterion, including two low-intensity rainfall (R-L) treatments and two high-intensity rainfall (R-H) treatments. Each experiment consisted of a 48 h runoff disturbance stage followed by a 48 h recovery stage. The dynamics of carbon (C), nitrogen (N), and phosphorus (P) in both water and sediments were systematically analyzed, together with variations in dissolved organic matter (DOM) composition, microbial communities based on 16S rRNA, and predicted N-cycling functional potential. Results showed that R-H exerted a pronounced dilution effect on pollutants in water but significantly enhanced SWI disturbance, facilitating nutrient accumulation within the system. DOM profiles indicated active microbial metabolism, consistent with long-term reclaimed water inputs. Microbial analyses revealed that TN was a key environmental factor influencing community differences. Nitrification and denitrification potentials were higher under R-H, whereas ammonia assimilation was higher under R-L. These findings highlight the importance of managing N accumulation and transformation following rainfall events in reclaimed water-receiving rivers.
Xue et al. (Sat,) studied this question.