Abstract: Atmospheric nitrate (NO₃^-) is a key product generated through the reaction of nitrogen oxides (NOx) with various oxidants such as ozone (O₃) and hydroxyl radicals (OH). It is one of the main pollutants in the atmosphere, significantly impacting air quality, climate, and ecosystems. This paper reviews the formation mechanisms, oxidation pathways, and global distribution of nitrogen and oxygen isotopic characteristics of nitrate in the marine atmosphere. The role of different oxidants, such as ozone and hydroxyl radicals, in nitrate formation is discussed. Based on global observation data, it is found that the isotopic composition of nitrogen and oxygen in nitrate (such as δ ¹⁵N and δ ¹⁸O) varies significantly across different marine areas and coastal cities, which may reflect regional differences in pollution sources, types of oxidants, photochemical conditions, and atmospheric reaction pathways. In addition, atmospheric nitrate can enter the ocean through atmospheric deposition, influencing the marine nitrogen cycle. Future studies should focus on enhancing long-term monitoring and data collection in different global regions to improve the quantitative assessment of oxidant contributions. This will enable a more comprehensive understanding of the formation mechanisms of atmospheric nitrate and its potential impact on marine ecosystems and climate change.

Key words: Stable isotopes, Nitrate, Marine atmosphere, Atmospheric nitrate in marine environments, NOx