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| Titel |
Dust storms come to Central and Southwestern China, too: implications from a major dust event in Chongqing |
| VerfasserIn |
Q. Zhao, K. He, K. A. Rahn, Y. Ma, Y. Jia, F. Yang, F. Duan, Y. Lei, G. Chen, Y. Cheng, H. Liu, S. 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 ; 10, no. 6 ; Nr. 10, no. 6 (2010-03-18), S.2615-2630 |
| Datensatznummer |
250008245
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| Publikation (Nr.) |
 copernicus.org/acp-10-2615-2010.pdf |
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| Zusammenfassung |
| Dust storms from major Asian sources are usually carried by northwesterly or
westerly winds over Northern and Southeastern China to the Pacific Ocean.
These pathways leave Central and Southwestern China nearly free of
incursions. But a strong dust event on 5–6 May 2005 was captured in a
15-month series of weekly filter samples of PM2.5 at three sites in
Chongqing. It illustrated that desert dust can be transported to this
region, and sometimes strongly. Annual PM2.5 and dust were similar at
the three sites, but higher than in simultaneous samples in Beijing. High
correlations of dust concentrations were found between the cities during
spring, indicating that Asian dust affects a broader swath of China than is
often realized. During the event, the concentrations of mineral dust were
high at all sites (20–30 μg m−3; 15%–20% of PM2.5 in
Chongqing, and 15 μg m−3; 20%–30% of PM2.5 in Beijing), and
were part of a broader spring maximum. The proportions of crustal elements
and pollution-derived components such as Pb, SO42−, and organic
carbon indicated that the sources for this dust differed from Beijing. The
dust was considerably enriched in Ca and Mg, characteristic of western
deserts, whereas Beijing's dust had the lower Ca and Mg of eastern deserts.
This observation agrees with synoptic patterns and back-trajectories. Driven
by a cold air outbreak from the northwest, dust from the western Gobi Desert
was transported at lower altitudes (<2 km above ground level), while dust
from the Takla Makan Desert was transported to Chongqing at higher
altitudes. Desert dust can also be important to wide areas of China during
the cold season, since almost all the weekly dust peaks in the two cities
coincided with extensive dust emissions in source regions. These findings
collectively suggest that the amount Asian-dust in China has been
underestimated both spatially and temporally, and that transported alkaline
dust can even be mitigating the effects of acidic deposition in Southern
China. |
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