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| Titel |
Seasonal and spatial variability of the OM/OC mass ratios and high regional correlation between oxalic acid and zinc in Chinese urban organic aerosols |
| VerfasserIn |
L. Xing, T.-M. Fu, J. J. Cao, S. C. Lee, G. H. Wang, K. F. Ho, M.-C. Cheng, C.-F. You, T. J. Wang |
| 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 ; 13, no. 8 ; Nr. 13, no. 8 (2013-04-25), S.4307-4318 |
| Datensatznummer |
250018609
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| Publikation (Nr.) |
 copernicus.org/acp-13-4307-2013.pdf |
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| Zusammenfassung |
| We calculated the organic matter to organic carbon mass ratios (OM/OC mass
ratios) in PM2.5 collected from 14 Chinese cities during summer and
winter of 2003 and analyzed the causes for their seasonal and spatial
variability. The OM/OC mass ratios were calculated two ways. Using a mass
balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39
year-round, with no significant seasonal or spatial variation. The second
calculation was based on chemical species analyses of the organic compounds
extracted from the PM2.5 samples using dichloromethane/methanol and
water. The calculated OM/OC mass ratio in summer was relatively high
(1.75 ± 0.13) and spatially-invariant due to vigorous photochemistry
and secondary organic aerosol (OA) production throughout the country. The
calculated OM/OC mass ratio in winter (1.59 ± 0.18) was significantly
lower than that in summer, with lower values in northern cities (1.51 ± 0.07)
than in southern cities (1.65 ± 0.15). This likely reflects the
wider usage of coal for heating purposes in northern China in winter, in
contrast to the larger contributions from biofuel and biomass burning in
southern China in winter. On average, organic matter constituted 36% and
34% of Chinese urban PM2.5 mass in summer and winter, respectively.
We report, for the first time, a high regional correlation between Zn and
oxalic acid in Chinese urban aerosols in summer. This is consistent with the
formation of stable Zn oxalate complex in the aerosol phase previously
proposed by Furukawa and Takahashi (2011). We found that many other
dicarboxylic acids were also highly correlated with Zn in the summer Chinese
urban aerosol samples, suggesting that they may also form stable organic
complexes with Zn. Such formation may have profound implications for the
atmospheric abundance and hygroscopic properties of aerosol dicarboxylic
acids. |
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