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| Titel |
Typical types and formation mechanisms of haze in an Eastern Asia megacity, Shanghai |
| VerfasserIn |
K. Huang, G. Zhuang, Y. Lin, J. S. Fu, Q. Wang, T. Liu, R. Zhang, Y. Jiang, C. Deng, Q. Fu, N. C. Hsu, B. Cao |
| 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. 1 ; Nr. 12, no. 1 (2012-01-02), S.105-124 |
| Datensatznummer |
250010424
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| Publikation (Nr.) |
 copernicus.org/acp-12-105-2012.pdf |
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| Zusammenfassung |
| An intensive aerosol and gases campaign was performed at Shanghai in the
Yangtze River Delta region over Eastern China from late March to early June
2009. This study provided a complementary picture of typical haze types and
the formation mechanisms in megacities over China by using a synergy of
ground-based monitoring, satellite and lidar observations. During the whole
study period, several extreme low visibility periods were observed with
distinct characteristics, and three typical haze types were identified,
i.e. secondary inorganic pollution, dust, and biomass burning. Sulfate,
nitrate and ammonium accounted for a major part of PM2.5 mass during
the secondary inorganic pollution, and the good correlation between
SO2/NOx/CO and PM2.5 indicated that coal burning and vehicle
emission were the major sources. Large-scale regions with high AOD (aerosol optical
depths) and low
Ångström exponent were detected by remote-sensing observation during
the dust pollution episode, and this episode corresponded to coarse
particles rich in mineral components such as Al and Ca contributing 76.8%
to TSP. The relatively low Ca/Al ratio of 0.75 along with the air mass
backward trajectory analysis suggested the dust source was from Gobi Desert.
Typical tracers for biomass burning from satellite observation (column CO
and HCHO) and from ground measurement (CO, particulate K+, OC, and EC)
were greatly enhanced during the biomass burning pollution episode. The
exclusive linear correlation between CO and PM2.5 corroborated that
organic aerosol dominated aerosol chemistry during biomass burning, and the
high concentration and enrichment degree of arsenic (As) could be also
partly derived from biomass burning. Aerosol optical profile observed by
lidar demonstrated that aerosol was mainly constrained below the boundary
layer and comprised of spheric aerosol (depolarization ratio <5%)
during the secondary inorganic and biomass burning episodes, while thick
dust layer distributed at altitudes from near surface to 1.4 km (average
depolarization ratio = 0.122 ± 0.023) with dust accounting for
44–55% of the total aerosol extinction coefficient during the dust
episode. This study portrayed a good picture of the typical haze types and
proposed that identification of the complicated emission sources is
important for the air quality improvement in megacities in China. |
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