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| Titel |
Investigation of aged aerosols in size-resolved Asian dust storm particles transported from Beijing, China, to Incheon, Korea, using low-Z particle EPMA |
| VerfasserIn |
H. Geng, H. Hwang, X. Liu, S. Dong, C.-U. Ro |
| 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 ; 14, no. 7 ; Nr. 14, no. 7 (2014-04-03), S.3307-3323 |
| Datensatznummer |
250118560
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| Publikation (Nr.) |
 copernicus.org/acp-14-3307-2014.pdf |
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| Zusammenfassung |
| This is the first study of Asian dust storm (ADS) particles collected in
Beijing, China, and Incheon, Korea, during a spring ADS event. Using a
seven-stage May impactor and a quantitative electron probe X-ray
microanalysis (ED-EPMA, also known as low-Z particle EPMA), we examined the
composition and morphology of 4200 aerosol particles at stages 1–6 (with a
size cut-off of 16, 8, 4, 2, 1, and 0.5 μm in equivalent
aerodynamic diameter, respectively) collected during an ADS event on 28–29
April 2005. The results showed that there were large differences in the
chemical compositions between particles in sample S1 collected in Beijing
immediately after the peak time of the ADS and in samples S2 and S3, which
were collected in Incheon approximately 5 h and 24 h later, respectively.
In sample S1, mineral dust particles accounted for more than 88% in
relative number abundance at stages 1–5; and organic carbon (OC) and reacted
NaCl-containing particles accounted for 24% and 32%, respectively,
at stage 6. On the other hand, in samples S2 and S3, in addition to
approximately 60% mineral dust, many sea spray aerosol (SSA) particles
reacted with airborne SO2 and NOx (accounting for 24%
and 14% on average in samples S2 and S3, respectively), often mixed with
mineral dust, were encountered at stages 1–5, and (C, N, O, S)-rich
particles (likely a mixture of water-soluble organic carbon with
(NH4)2SO4 and NH4NO3) were abundantly observed at
stage 6 (accounting for 68% and 51% in samples S2 and S3,
respectively). This suggests that an accumulation of sea-salt components on
individual ADS particles larger than 1 μm in diameter occurred and
many secondary aerosols smaller than 1 μm in diameter were formed
when the ADS particles passed over the Yellow Sea. In the reacted or aged
mineral dust and SSA particles, nitrate-containing and both nitrate- and
sulfate-containing species vastly outnumbered the sulfate-containing species,
implying that ambient NOx had a greater influence on the
atmospheric particles than SO2 during this ADS episode. In addition to
partially- or totally-reacted CaCO3, reacted or aged Mg-containing
aluminosilicates were observed frequently in samples S2 and S3;
furthermore, a student's t test showed that both their atomic concentration
ratios of [Mg] / [Al] and [Mg] / [Si] were significantly elevated
(P < 0.05) compared to those in samples S1 (for [Mg] / [Al],
0.34 ± 0.09 and 0.40 ± 0.03 in samples S2 and S3, respectively,
vs. 0.24 ± 0.01 in sample S1; for [Mg] / [Si], 0.21 ± 0.05 and
0.22 ± 0.01 in samples S2 and S3, respectively, vs. 0.12 ± 0.02 in
sample S1). The significant increase of [Mg] / [Al] and [Mg] / [Si]
ratios in Mg-containing aluminosilicates indicates that a significant evolution or
aging must have occurred on the ADS particles in the marine atmosphere during
transport from China to Korea. |
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