P inputs determine denitrifier abundance explaining dissolved nitrous oxide in reservoirs

Reservoirs are important sites for nitrogen processing, especially those located in agricultural and urban watersheds. Nitrogen inputs promote N2O production emission, but the microbial pathways controlling have been seldom studied reservoir water columns. We determined concentration column of 12 reservoirs during summer stratification winter mixing. explored potential sources sinks by quantifying key genes involved ammonia oxidation (bacterial archaeal amoA) denitrification (nirS nosZ). Dissolved varied up to three orders magnitude (4.7–2441.2 nmol L−1) across systems, from undersaturated supersaturated values (37%–24,174%) depending on depths. depended oxygen availabilities, with lowest highest at suboxic conditions. Ammonia-oxidizing archaea dominated over ammonia-oxidizing bacteria were not related dissolved N2O. In contrast, abundance nirS gene was significantly concentration, higher than amoA abundance. Denitrifying appeared consistently all reservoirs. The nosZ oxic waters, they more abundant waters. nitrate relative abundances explained Besides, positively total phosphorus cumulative chlorophyll a, a proxy fresh organic matter. Therefore, P inputs, just N promoted