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| Titel |
Observation of atmospheric aerosols at Mt. Hua and Mt. Tai in central and east China during spring 2009 – Part 2: Impact of dust storm on organic aerosol composition and size distribution |
| VerfasserIn |
G. H. Wang, J. J. Li, C. L. Cheng, B. H. Zhou, M. J. Xie, S. Y. Hu, J. J. Meng, T. Sun, Y. Q. Ren, J. J. Cao, S. X. Liu, T. Zhang, Z. Z. Zhao |
| 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 ; 12, no. 9 ; Nr. 12, no. 9 (2012-05-08), S.4065-4080 |
| Datensatznummer |
250011120
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| Publikation (Nr.) |
 copernicus.org/acp-12-4065-2012.pdf |
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| Zusammenfassung |
PM10 and size-resolved particles (9-stage) were
simultaneously collected at Mt. Hua and Mt. Tai in central and east China
during the spring of 2009 including a massive dust storm occurring on 24 April
(named as DS II), and determined for organic compounds to
investigate the impact of dust storm on organic aerosols. High molecular
weight (HMW) n-alkanes, fatty acids, and fatty alcohols and trehalose sharply
increased and almost entirely stayed in coarse particles when dust storm was
present, suggesting that high level of organic aerosols in the mountain
atmospheres during the event largely originated from Gobi desert plants.
However, most anthropogenic aerosols (e.g. PAHs, and aromatic and
dicarboxylic acids) during the event significantly decreased due to a
dilution effect, indicating that anthropogenic aerosols in the mountain
atmospheres during the nonevent period largely originated from
local/regional sources rather than from long-range transport. Trehalose, a
metabolism product enriched in biota in dry conditions, was 62 ± 78 and
421 ± 181 ng m−3 at Mt. Hua and Mt. Tai during DS II, 10–30 times
higher than that in the nonevent time, indicating that trehalose may be a
tracer for dust emissions from Gobi desert regions. Molecular compositions
of organic aerosols in the mountain samples demonstrate that domestic coal
burning is still the major source of PAHs in China.
n-Alkanes and fatty acids showed a bimodal size distribution during the
nonevent with a major peak in fine mode (<2.1 μm) and a small peak in
coarse mode (>2.1 μm). The coarse mode significantly increased and
even dominated over the whole size range when dust was present. Glucose and
trehalose were also dominant in the coarse mode especially in the DS II
time. PAHs and levoglucosan concentrated in fine particles with no
significant changes in size distribution when dust storm occurred. However,
phthalic and succinic acids showed bimodal size distribution pattern with an
increase in coarse mode during the event, because both are formed via a gas
phase oxidation and a subsequent condensation/adsorption onto aerosol phase.
In contrast, terephthalic and malic acids are mostly emitted from combustion
process as fine particles, thus both showed a fine mode pattern during the
whole campaign with a minor peak in coarse mode caused by an increased
coagulation with dust during the event. Geometric mean diameters (GMDs) of
the organic aerosols above are in general larger at Mt.~Hua than at Mt. Tai
during the nonevent period. We found that during the event GMD of the fine
mode organics that derived mostly from the local/regional sources rather
than Gobi desert became smaller while GMD of them in coarse mode became
larger. Such a splitting in sizes during the event is most likely caused by
decreased fine particle coagulation due to dilution and increased
adsorption/coagulation with dust. |
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