[Research progress on the monitoring methods of atmospheric nitrogen deposition]

As an important component of global nitrogen (N) biogeochemical cycle, atmospheric N deposition refers to the removal process of reactive N, including oxidized N (NO_y) and reduced N (NH_x), from the atmosphere to earth surface through dry and wet deposition. Nitrogen deposition can exert important impacts on the structure and functioning of both terrestrial and aquatic ecosystems. Increasing N deposition poses a potential threat to natural ecosystems and human health. It is a challenge to accurately monitor the composition and flux of dry and wet N deposition in different ecosystems, using a unified technology. Here, we reviewed the research progress on monitoring methods of dry and wet N deposition in China and aboard, including micrometeorology, inferential method, model estimation, surrogate surface, precipitation collection, and ion exchange resin methods. We further discussed the advantages and disadvantages of each method in terms of its applications at regional, national, and global scales. This review would provide a methodological support to establish national monitoring network for atmospheric N deposition.