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| Titel |
Anthropogenic imprints on nitrogen and oxygen isotopic composition of precipitation nitrate in a nitrogen-polluted city in southern China |
| VerfasserIn |
Y. T. Fang, K. Koba, X. M. Wang, D. Z. Wen, J. Li, Y. Takebayashi, X. Y. Liu, M. Yoh |
| 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 ; 11, no. 3 ; Nr. 11, no. 3 (2011-02-15), S.1313-1325 |
| Datensatznummer |
250009309
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| Publikation (Nr.) |
 copernicus.org/acp-11-1313-2011.pdf |
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| Zusammenfassung |
| Nitric acid (HNO3) or nitrate (NO3−) is the dominant sink for
reactive nitrogen oxides (NOx = NO + NO2) in the atmosphere. In
many Chinese cities, HNO3 is becoming a significant contributor to acid
deposition. In the present study, we measured nitrogen (N) and oxygen (O)
isotopic composition of NO3− in 113 precipitation samples
collected from Guangzhou City in southern China over a two-year period (2008
and 2009). We attempted to better understand the spatial and seasonal
variability of atmospheric NOx sources and the NO3− formation
pathways in this N-polluted city in the Pearl River Delta region. The
δ15N values of NO3− (versus air N2) ranged from
−4.9 to +10.1‰, and averaged +3.9‰ in 2008 and +3.3‰ in 2009. Positive
δ15N values were observed throughout the year, indicating the
anthropogenic contribution of NOx emissions, particularly from coal
combustion. Different seasonal patterns of δ15N-NO3−
were observed between 2008 and 2009, which might reflect different human
activities associated with the global financial crisis and the intensive
preparations for the 16th Asian Games. Nitrate δ18O values
(versus Vienna Standard Mean Ocean Water) varied from +33.4 to +86.5‰
(average +65.0‰ and +67.0‰ in 2008 and 2009, respectively), a range being
lower than those reported for high latitude and polar areas. Sixteen percent
of δ18O values was observed lower than the expected minimum of
+55‰ at our study site. This was likely caused by the reaction of NO with
peroxy radicals; peroxy radicals can compete with O3 to convert NO to
NO2, thereby donate O atoms with much lower δ18O value
than that of O3 to atmospheric NO3−. Our results highlight
that the influence of human activities on atmospheric chemistry can be
recorded by the N and O isotopic composition of atmospheric NO3−
in a N-polluted city. |
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