Sediment Properties and NosZ I Community Drive Nitrous Oxide Emissions in the Continuously Flooded Area of a Typical Urban Lake

Urban lakeshore zones characterized by highly spatiotemporal heterogeneity serve as critical hotspots for N 2 O emissions. While nosZ I communities contribute to nitrous oxide (N 2 O) sink potential, their regulatory mechanisms in the urban lakeshores remain unexplored. Here, we investigated the variations and driving patterns of N 2 O fluxes and nitrogen (N) removal rates in continuously flooded (CF), semi‐flooded (SF), and non‐flooded (NF) zones of Pipa Lake in China during both summer and winter. Results revealed that CF zones exhibited seasonal N 2 O sink–source shifts (−14.73 and 9.00 μg m −2 hr −1 for summer and winter, respectively) and higher potential denitrification rates (0.63−43.73 nmol N g −1 hr −1 ) compared to SF and NF zones. These shifts were likely driven by seasonal variations in nosZ I community abundance and composition in CF zones, for example, significantly reduced nosZ I gene abundance ( P < 0.05), and remarkably enriched taxa Azospirizaceae (40.43%) in the winter. Additionally, sediment carbon and nitrogen substrates exerted stronger direct effects on N 2 O emissions than indirect effects mediated by nosZ I communities, while moisture regulated N 2 O emissions by suppressing nosZ I abundance and enhancing carbon substrates. Under projected urban expansion scenarios, the CF zone would be a potential hotspot for N 2 O emissions, thereby exacerbating climate change. Consequently, managing sediment carbon and nitrogen substrates to modulate nosZ I communities would present a viable strategy for N 2 O mitigation in urban lakeshores.