Impacts of climate change and emissions on atmospheric oxidized nitrogen deposition over East Asia

Abstract

A multi-model ensemble of Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) simulations is used to study the atmospheric oxidized nitrogen (NO y ) deposition over East Asia under climate and emission changes projected for the future. Both dry and wet NO y deposition show significant decreases in the 2100s under RCP4.5 and RCP8.5, primarily due to large anthropogenic emission reduction over both land and sea. However, in the near future of the 2030s, both dry and wet NO y deposition increase significantly due to continued increase in emissions. Marine primary production from both dry and wet NO y deposition increases by 19 %-34 % in the 2030s and decreases by 34 %-63 % in the 2100s over the East China Sea. The individual effect of climate or emission changes on dry and wet NO y deposition is also investigated. The impact of climate change on dry NO y deposition is relatively minor, but the effect on wet deposition, primarily caused by changes in precipitation, is much higher. For example, over the East China Sea, wet NO y deposition increases significantly in summer due to climate change by the end of this century under RCP8.5, which may subsequently enhance marine pri-mary production. Over the coastal seas of China, as the transport of NO y from land becomes weaker due to the decrease in anthropogenic emissions, the effect of ship emissions and lightning emissions becomes more important. On average, the seasonal mean contribution of ship emissions to total NO y deposition is projected to be enhanced by 24 %-48 % and 3 %-37 % over the Yellow Sea and East China Sea, respectively, by the end of this century. Therefore, continued control of both anthropogenic emissions over land and ship emissions may reduce NO y deposition to the Chinese coastal seas.

Ammonia emission abatement does not fully control reduced forms of nitrogen deposition

“…Implementation of emission controls is an effective avenue to reduce acid deposition (3,(16)(17)(18). In the United States, oxidized nitrogen (NO y , sum of all oxidized nitrogen species except nitrous oxide [N 2 O]) deposition, a result of nitrogen oxides (NO x = NO + NO 2 ) emissions from combustion, has been reduced since implementation of the Clean Air Act (CAA) in the 1970s.…”

Quantifying the Impact of Anthropogenic Atmospheric Nitrogen Deposition on the Generation of Hypoxia under Future Emission Scenarios in Chinese Coastal Waters

“…To estimate future changes in N deposition in China, we used the projected percentage changes of dry and wet N deposition in the 2030s (2030−2039) and 2100s (2100− 2109) under RCP 4.5 and RCP 8.5 scenarios reported in Zhang et al, 95 which used the results from ACCMIP models. The future scenarios considered both the impact of climate change and emissions.…”

“…Therefore, we assume riverine input remains constant in future scenarios to isolate the impact from atmospheric deposition. The uncertainty of the extent of hypoxic areas predicted for future scenarios is calculated based on the standard deviations of future N deposition in the ACCMIP models, which was reported in Zhang et al 95 ■ RESULTS…”

Aerosol Nutrients and Their Biological Influence on the Northwest Pacific Ocean (NWPO) and Its Marginal Seas

“…Now, in many estuarine and coastal zones, the atmospheric N loading could equal or even exceed riverine N inputs because of the dramatic increase in anthropogenic emissions [ 31 ]. Globally, atmospheric deposition could bring ~39–67 Tg N year −1 to the ocean [ 39 ], which is ~3 fold higher than in the preindustrial period, and is predicted to grow over the coming decades [ 4 , 40 , 41 ]. The quantity of atmospheric N deposition is also approaching that of global oceanic N 2 fixation (~100 Tg year −1 ) [ 42 , 43 , 44 , 45 ], and could account for up to about a third of the ocean’s total external N supply [ 4 ].…”