Monthly dynamics of atmospheric wet nitrogen deposition on different spatial scales in China.

China is one of three global hotspots for nitrogen (N) deposition, which has concerned scientists and the public. While previous studies on N deposition in China have focused on its composition, spatial pattern, and interannual dynamics, its monthly dynamics in different regions remain unclear, hindering our ability to evaluate its ecological effects. Therefore, we obtained monthly wet N deposition data from196 sites after continuous network observations and published data in China and analyzed the monthly dynamics of NH-N, NO-N, and dissolved inorganic N (DIN=NH-N+NO-N) deposition fluxes on site, regional, and national scales. We observed that the deposition fluxes of NH-N, NO-N, and DIN in China showed clear monthly patterns and regional differences. In Northern China, wet N deposition predominantly showed a unimodal trend, whereas in Southern China, it revealed a bimodal trend or irregular fluctuations. During 2000-2016, NH-N, NO-N, and DIN deposition fluxes were estimated as 9.09, 6.12, and 15.21 kg N ha year., respectively. Our findings enhance our understanding of atmospheric wet N deposition, and can serve as a reference for N deposition simulation experiments in different regions, and for generating long-term N deposition data for model optimization. Regional differences in the monthly dynamics of wet N deposition should be emphasized to accurately evaluate its ecological effects on terrestrial ecosystems in different regions.