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| Titel |
Wet deposition of atmospheric inorganic nitrogen at five remote sites in the Tibetan Plateau |
| VerfasserIn |
Y. W. Liu, Xu-Ri, Y. S. Wang, Y. P. Pan, S. L. Piao |
| 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. 20 ; Nr. 15, no. 20 (2015-10-21), S.11683-11700 |
| Datensatznummer |
250120111
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| Publikation (Nr.) |
 copernicus.org/acp-15-11683-2015.pdf |
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| Zusammenfassung |
| Since the mid-20th century, nitrogen (N) deposition has shown an increasing
trend in the Tibetan Plateau (TP), where alpine ecosystems are sensitive to
elevated N deposition. However, the quantitative characterization of N
deposition in the TP remains unclear, due in most part to the lack of in situ
measurement. Using the Tibetan Observation and Research Platform network, we
conducted short-term in situ measurements of major ions (NO3−, Cl−,
SO42−, NH4+, Na+, K+, Ca2+, and
Mg2+) wet deposition at five remote sites in the TP during 2011–2013.
At Southeast Tibet Station, Nam Co Station, Qomolangma Station, Ngari
Station, and Muztagh Ata Station, the NH4+–N wet deposition was
0.63, 0.68, 0.92, 0.36, and 1.25 kg N ha−1 yr−1, respectively; the
NO3−–N wet deposition was 0.28, 0.24, 0.03, 0.08, and 0.30 kg N ha−1 yr−1, respectively; and the inorganic N wet deposition was
0.91, 0.92, 0.94, 0.44, and 1.55 kg N ha−1 yr−1, respectively. The
inorganic N wet deposition mainly occurred in the form of NH4+–N
during summer at all sites. Results of enrichment factor analysis and
principal component analysis demonstrated that both NH4+–N and
NO3−–N wet deposition in the TP were mainly influenced by
anthropogenic activities. Backward trajectory analysis showed that the
inorganic N deposition at Muztagh Ata Station was mainly transported from
central Asia and the Middle East through westerlies. At Southeast Tibet Station,
Nam Co Station, Qomolangma Station, and Ngari Station, the inorganic N
deposition was mainly contributed by anthropogenic sources in south Asia,
and was mainly transported by the Indian monsoon. Combining site-scale in situ
measurements of inorganic N wet deposition in this and previous studies, the
average wet deposition of atmospheric NH4+–N, NO3−–N,
and inorganic N in the TP was estimated to be 1.06, 0.51, and 1.58 kg N ha−1 yr−1, respectively. The average
NH4+–N : NO3−–N ratio in precipitation in the TP was
approximately 2 : 1. Results from the present study suggest that earlier
estimations based on chemical transport model simulations and/or limited
field measurements likely overestimated substantially the regional inorganic
N wet deposition in the TP. To clarify the total N deposition in the TP more
clearly, it is essential to conduct long-term monitoring of both wet and dry
deposition of atmospheric N in various climate zones in the TP in the
future. |
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