Abstract: Estuarine and coastal waters, serving as the interface between terrestrial and marine ecosystems, play a pivotal role in the biogeochemical cycling of nitrous oxide (N₂O). The potent greenhouse gas has a profound impact on global climate change due to the distribution characteristics and microbial metabolic mechanisms of N₂O in estuarine and coastal waters. In this paper, we reviewed the distribution characteristics of N₂O in estuarine and coastal regions, the principal microbial metabolic pathways contributing to N₂O emissions, including nitrification, nitrifier denitrification, incomplete denitrification, and the coupling of nitrification with denitrification, as well as the methodologies for assessing N₂O production and consumption, and the environmental factors that influence N₂O emissions. Understanding the biogeochemical cycling of N₂O in estuarine and coastal waters is essential for devising effective management strategies to mitigate N₂O emissions, thereby protecting the global climate.

Key words: nitrogen metabolism, N₂O, biogeochemical cycle, estuarine and coastal waters