Contributions of Long-range Transport of Air Pollutants on the Atmospheric Deposition in Coastal Regions

Serving as places for air-sea exchanges, coastal regions have been identified with vulnerable ecosystems. The exceedance of deposition in coastal regions is associated with various environmental issues, including acidification and eutrophication of the waterbody, threats to coastal benthic and planktonic system and sustainability of fishery. Recent studies have reported significant impacts of long-range transport of air pollutants on aggravating the regional air pollution. However, the impacts on deposition in the coastal regions haven't been studies in this detail. This study uses the multi-model ensemble results from 14 global models to study the impacts of long-range transport on the sulfur (S) and nitrogen (N) deposition in the coasts of 5 regions, including North America, Europe, South Asia, East Asia and Russia. The results show that the deposition in the coastal regions is about twice more sensitive to long-range transport than non-coastal regions. Upmost half of the long-range transport of air pollutants or oxidation products from foreign regions are deposited over the coastal regions. In particular, 5% of the S and N emissions from East Asia are transported to Far East Russia, and about half of them are deposited over the Russian coasts. For some coastal regions such as the west coast of North America and the west coast of Europe, the contributions of long-range transport are even higher than those of controlling domestic emissions. For instance: The S deposition in the west coast of North America receives 2-6% decreases in its S deposition when controlling 20% of S emissions in East Asia, while the effects of controlling 20% of its own region emissions are less than 1%. This study highlights the significant contributions of long-range transport of air pollutants on the atmospheric deposition in coastal regions. We suggest further study on the measurements and impacts on the coastal ecosystem.