Untangling the impacts of bacterial community on carbon dioxide and nitrous oxide across a drinking water reservoir

Reservoirs represent a critical component of greenhouse gas (GHG) emissions, yet the intricacies of how biotic and abiotic factors influence GHG dynamics within reservoirs remain largely unexplored. Herein, we investigated the spatiotemporal patterns of CO₂ and N₂O emissions and the underlying factors in the Danjiangkou Reservoir, Asia's largest artificial freshwater reservoir. We found that this reservoir was a significant source of GHGs to the atmosphere, with peak CO₂ emissions observed in autumn (1544.39 ± 652.53 μatm) and N₂O emissions in winter (32.57 ± 8.87 μmol/L). Moreover, we identified crucial bacterial biomarkers that regulate GHG dynamics, and these GHG biomarkers exhibited consistent seasonal patterns with the corresponding GHGs, concerning their abundance and niche breadth. Notably, GHG biomarkers displayed larger effects on the variations of N₂O than CO₂ emissions, while physiochemical variables were more critical for CO₂ dynamics, highlighting the need to consider both biotic and abiotic factors when evaluating GHG emissions from reservoirs. Overall, this study advanced our knowledge of GHG emissions and their driving mechanisms in artificial reservoirs, emphasizing the importance of functional microbes in estimating and managing CO₂ and N₂O emissions from artificial reservoirs worldwide.