The biogeochemical responses of hyporheic groundwater to the long-run managed aquifer recharge: Linking microbial communities to hydrochemistry and micropollutants

Abstract

Interactions of surface water and groundwater (SW–GW) in hyporheic zones produce biogeochemical hotspots. However, response patterns of hyporheic groundwater to external influences remain unclear. In this study, three datasets (hydrochemistry, antibiotics, and microbiome) were collected over a hydrological year to explore the influence of a 12-year managed aquifer recharge (MAR) project. We observed that the long-term MAR practice elevated nutrient and antibiotic levels while reduced redox potential in hyporheic groundwater, and these impacts depended on decreasing SW–GW interaction intensity with aquifer depth. In contrast, the long-term MAR practice increased community dissimilarity of 30-m groundwater but had little impact on 50-m or 80-m groundwater. Moreover, hyporheic community assembly was dominated by dispersal limitation, and thereby co-varied hydrochemistry and antibiotics only attributed to small community variability. The long-term MAR practice decreased species-interaction intensity and changed the abundance of metabolic functions in hyporheic groundwater. Furthermore, predicted community functions involving carbon, nitrogen, sulfur, and manganese cycles for 30-m groundwater showed higher abundances than those for 50- and 80-m groundwater. Collectively, we showed that hyporheic groundwater was sensitive to the SW–GW interaction and human activities, with the interactions of hydrochemistry, contaminants, and microbiome linking to hyporheic groundwater quality and ecosystem functioning.