Characterization of the distribution of dissolved nitrous oxide and methane concentrations and air-sea fluxes in China Sea and their impact mechanisms

Nitrous oxide (N₂O) and methane (CH₄) are important greenhouse gases, and their greenhouse effects affect the global climate. However, the current researches on dissolved N₂O and CH₄ in China Sea are limited and lack of systematic researches and organizations. In this paper, the concentration distribution characteristics of dissolved N₂O and CH₄ in Bohai Sea, the Yellow Sea, East China Sea, the South China Sea and the sea-air exchange fluxes in the past 30 years are summarized and it is found that the spatial distribution of N₂O and CH₄ concentrations in the surface layer of China Sea generally shows a gradual decrease from the north to the south, and is negatively correlated with the rising temperature. The annual emission of N₂O in China Sea accounts for about 8.6%−9.8% of the global oceanic N₂O emission. The annual emission of CH₄ accounts for about 2.5%−2.6% of the global oceanic CH₄ emission. The factors affecting the production and release of N₂O and CH₄ show that land source input and sediment-water interface exchange are important sources in the water column. It is recommended to standardize the observation methods, strengthen the acquisition of high-precision continuous data, and combine big data such as satellite remote sensing with isotope and biochemical techniques to more precisely assess the emissions of N₂O and CH₄ in China Sea, thereby providing a scientific foundation for evaluating the potential greenhouse effects of non-carbon dioxide greenhouse gases in the China Sea.