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| Titel |
Aerosol composition, sources and processes during wintertime in Beijing, China |
| VerfasserIn |
Y. L. Sun, Z. F. Wang, P. Q. Fu, T. Yang, Q. Jiang, H. B. Dong, J. Li, J. J. Jia |
| 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. 9 ; Nr. 13, no. 9 (2013-05-02), S.4577-4592 |
| Datensatznummer |
250018627
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| Publikation (Nr.) |
 copernicus.org/acp-13-4577-2013.pdf |
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| Zusammenfassung |
| Air pollution is a major environmental concern during all seasons in the megacity
of Beijing, China. Here we present the results from a winter study that was
conducted from 21 November 2011 to 20 January 2012 with an Aerodyne
Aerosol Chemical Speciation Monitor (ACSM) and various collocated
instruments. The non-refractory submicron aerosol (NR-PM1) species vary
dramatically with clean periods and pollution episodes alternating
frequently. Compared to summer, wintertime submicron aerosols show much
enhanced organics and chloride, which on average account for 52% and
5%, respectively, of the total NR-PM1 mass. All NR-PM1 species
show quite different diurnal behaviors between summer and winter. For
example, the wintertime nitrate presents a gradual increase during daytime
and correlates well with secondary organic aerosol (OA), indicating a
dominant role of photochemical production over gas–particle partitioning.
Positive matrix factorization was performed on ACSM OA mass spectra, and
identified three primary OA (POA) factors, i.e., hydrocarbon-like OA (HOA),
cooking OA (COA), and coal combustion OA (CCOA), and one secondary factor,
i.e., oxygenated OA (OOA). The POA dominates OA during wintertime,
contributing 69%, with the other 31% being SOA. Further, all POA
components show pronounced diurnal cycles with the highest concentrations
occurring at nighttime. CCOA is the largest primary source during the
heating season, on average accounting for 33% of OA and 17% of
NR-PM1. CCOA also plays a significant role in chemically resolved
particulate matter (PM) pollution as its mass contribution increases
linearly as a function of NR-PM1 mass loadings. The SOA, however,
presents a reverse trend, which might indicate the limited SOA formation
during high PM pollution episodes in winter. The effects of meteorology on
PM pollution and aerosol processing were also explored. In particular, the
sulfate mass is largely enhanced during periods with high humidity because
of fog processing of high concentration of precursor SO2. In addition,
the increased traffic-related HOA emission at low temperature is also
highlighted. |
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