Coupled Effects of Acid Mine Drainage and Domestic Wastewater Reshape Sediment Microbial Communities

This study examines the contrasting responses of a karst river ecosystem to distinct pollution regimes by investigating the biogeochemical and microbial dynamics in two tributaries of the Yudong River Basin, China. The Baishui River receives primarily acidic mine drainage (AMD), while the Pinglu River is influenced by a combination of AMD and domestic wastewater. Results show that sediment microbial communities in the circumneutral Pinglu River exhibit significantly higher diversity, dominated by iron- and sulfur-cycling genera such as Gallionella and Geobacter . In contrast, the acidic Baishui River hosts less diverse communities dominated by acid-tolerant taxa like Sulfuriferula and Acidithiobacillus . Redundancy analysis reveals that 77.54% of microbial community variation is explained by environmental parameters, with pH and metal concentrations (e.g., Zn, Mn, Pb, Cu) identified as key determinants. These findings highlight how organic wastewater inputs can modulate AMD impacts in karst systems, supporting more diverse microbial assemblages, and underscore the necessity of integrated management strategies that consider both AMD neutralization and organic pollutant co-treatment in mining-affected watersheds.