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| Titel |
Exploring the severe winter haze in Beijing: the impact of synoptic weather, regional transport and heterogeneous reactions |
| VerfasserIn |
G. J. Zheng, F. K. Duan, H. Su, Y. L. Ma, Y. Cheng, B. Zheng, Q. Zhang, T. Huang, T. Kimoto, D. Chang, U. Pöschl, Y. F. Cheng, K. B. He |
| 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 ; 15, no. 6 ; Nr. 15, no. 6 (2015-03-17), S.2969-2983 |
| Datensatznummer |
250119553
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| Publikation (Nr.) |
 copernicus.org/acp-15-2969-2015.pdf |
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| Zusammenfassung |
| Extreme haze episodes repeatedly shrouded Beijing during the winter of
2012–2013, causing major environmental and health problems. To better
understand these extreme events, we performed a model-assisted analysis of
the hourly observation data of PM2.5 and its major chemical
compositions. The synthetic analysis shows that (1) the severe winter haze
was driven by stable synoptic meteorological conditions over northeastern
China, and not by an abrupt increase in anthropogenic emissions. (2)
Secondary species, including organics, sulfate, nitrate, and ammonium, were
the major constituents of PM2.5 during this period. (3) Due to the
dimming effect of high loading of aerosol particles, gaseous oxidant
concentrations decreased significantly, suggesting a reduced production of
secondary aerosols through gas-phase reactions. Surprisingly, the
observational data reveals an enhanced production rate of secondary
aerosols, suggesting an important contribution from other formation
pathways, most likely heterogeneous reactions. These reactions appeared to
be more efficient in producing secondary inorganics aerosols than organic
aerosols resulting in a strongly elevated fraction of inorganics during
heavily polluted periods. (4) Moreover, we found that high aerosol
concentration was a regional phenomenon. The accumulation process of aerosol
particles occurred successively from cities southeast of Beijing. The
apparent sharp increase in PM2.5 concentration of up to several hundred
μg m−3 per hour recorded in Beijing represented rapid recovery
from an interruption to the continuous pollution accumulation over the
region, rather than purely local chemical production. This suggests that
regional transport of pollutants played an important role during these
severe pollution events. |
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