Abstract:Nitrous oxide (N2O) is a powerful greenhouse gas, and also the main compound causing stratospheric ozone depletion. The ocean is an important source of N2O emission to the atmosphere, and N2O in the ocean is mainly produced by the microbial-mediated nitrogen biogeochemical cycle. This paper firstly reviews the marine N2O emission flux, the distribution characteristics of seawater N2O and environmental impact factors. Then, the microbial processes regulating the N2O production and emission are discussed. At last, we address the N2O biogeochemical process based on the relationship between low oxygen and N2O production in the estuarine and coastal ecosystems.