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| Titel |
Atmospheric nitrogen deposition to the northwestern Pacific: seasonal variation and source attribution |
| VerfasserIn |
Y. Zhao, L. Zhang, Y. Pan, Y. Wang, F. Paulot, D. K. Henze |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 18 ; Nr. 15, no. 18 (2015-09-30), S.10905-10924 |
| Datensatznummer |
250120067
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| Publikation (Nr.) |
 copernicus.org/acp-15-10905-2015.pdf |
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| Zusammenfassung |
| Rapid Asian industrialization has led to increased downwind atmospheric nitrogen
deposition threatening the marine environment. We present an
analysis of the sources and processes controlling atmospheric nitrogen
deposition to the northwestern Pacific, using the GEOS-Chem global chemistry
model and its adjoint model at 1/2° × 2/3°
horizontal resolution over East Asia and its adjacent oceans. We focus
our analyses on the marginal seas: the Yellow Sea and the South China Sea.
Asian nitrogen emissions in the model are 28.6 Tg N a−1 as NH3
and 15.7 Tg N a−1 as NOx. China has the largest sources with
12.8 Tg N a−1 as NH3 and 7.9 Tg N a−1 as NOx; the
high-NH3 emissions reflect its intensive agricultural activities. We
find Asian NH3 emissions are a factor of 3 higher in summer than winter.
The model simulation for 2008–2010 is evaluated with NH3 and NO2
column observations from satellite instruments, and wet deposition flux
measurements from surface monitoring sites. Simulated atmospheric nitrogen
deposition to the northwestern Pacific ranges
0.8–20 kg N ha−1 a−1, decreasing rapidly downwind of the Asian
continent. Deposition fluxes average 11.9 kg N ha−1 a−1 (5.0 as
reduced nitrogen NHx and 6.9 as oxidized nitrogen NOy) to the
Yellow Sea, and 5.6 kg N ha−1 a−1 (2.5 as NHx and 3.1 as
NOy) to the South China Sea. Nitrogen sources over the ocean (ship
NOx and oceanic NH3) have little contribution to deposition over
the Yellow Sea, about 7 % over the South China Sea, and become important
(greater than 30 %) further downwind. We find that the seasonality of
nitrogen deposition to the northwestern Pacific is determined by variations
in meteorology largely controlled by the East Asian monsoon and in nitrogen
emissions. The model adjoint further estimates that nitrogen deposition to
the Yellow Sea originates from sources over China (92 % contribution) and
the Korean peninsula (7 %), and by sectors from fertilizer use
(24 %), power plants (22 %), and transportation (18 %).
Deposition to the South China Sea shows source contribution from mainland China (66 %), Taiwan (20 %), and the rest (14 %) from the southeast
Asian countries and oceanic NH3 emissions. The adjoint analyses also
indicate that reducing Asian NH3 emissions would increase NOy dry
deposition to the Yellow Sea (28 % offset annually), limiting the
effectiveness of NH3 emission controls on reducing nitrogen deposition
to the Yellow Sea. |
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