Decadal Response of Atmospheric Inorganic Nitrogen Dry Deposition into Offshore Areas to Policy Controls and Environmental Significance

Accurately assessing the dry deposition fluxes of inorganic nitrogen aerosol (aerosol-IN) is crucial for mitigating the ecological damage caused by excessive nitrogen in oceanic equilibria. We developed a dry deposition model to assess the dry deposition fluxes of aerosol-IN into Chinese offshore areas over a decade, with the range of 2.81 × 106–1.89 × 107 g N km–2 year–1. Our findings showed a clear decline in the dry deposition fluxes of aerosol-IN following the implementation of environmental laws and policies. Promoting cleaner production, using new energy vehicles, the rational use of nitrogenous fertilizers, and standardized straw burning will all reduce pollution caused by excessive nitrogen deposition. High ratios of dry deposit to river transport nitrogen (0.48–17.89) indicate aerosol-IN is a significant source of inorganic nitrogen in Chinese offshore areas. The implementation of the policy has significantly reduced aerosol-IN deposition into the ocean, but its contribution remained substantial and should be considered when protecting the Chinese marine ecological environment.