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| Titel |
Aerosol physicochemical properties and implications for visibility during an intense haze episode during winter in Beijing |
| VerfasserIn |
Y. H. Wang, Z. R. Liu, J. K. Zhang, B. Hu, D. S. Ji, Y. C. Yu, Y. 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 ; 15, no. 6 ; Nr. 15, no. 6 (2015-03-23), S.3205-3215 |
| Datensatznummer |
250119568
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| Publikation (Nr.) |
 copernicus.org/acp-15-3205-2015.pdf |
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| Zusammenfassung |
| The evolution of physical, chemical and optical properties of urban aerosol
particles was characterized during an extreme haze episode in Beijing, PRC,
from 24 through 31 January 2013 based on in situ measurements. The
average mass concentrations of PM1, PM2.5 and PM10 were
99 ± 67 μg m−3 (average ± SD),
188 ± 128 μg m−3 and 265 ± 157 μg m−3, respectively. A significant increase in PM1-2.5
fraction was observed during the most heavily polluted period. The average
scattering coefficient at 550 nm was 877 ± 624 Mm−1. An
increasing relative amount of coarse particles can be deduced from the
variations of backscattering ratios, asymmetry parameter and scattering
Ångström exponent. Particle number-size distributions between 14 and 2500 nm diameter showed high number concentrations, particularly in the
nucleation mode and accumulation mode. Size-resolved chemical composition of
submicron aerosol from a high-resolution time-of-flight aerosol mass spectrometer
showed that the mass concentrations of organic, sulfate, nitrate, ammonium
and chlorine mainly resided on particles between 500 and 800 nm (vacuum diameter),
and nitrate and ammonium contributed greatly to particle growth during the
heavily polluted day (28 January).
Increasing relative humidity and stable synoptic conditions on 28 January
combined with heavy pollution on 28 January, leading to enhanced water uptake
by the hygroscopic submicron particles and formation of secondary aerosol,
which might be the main reasons for the severity of the haze episode.
Light-scattering apportionment showed that organic, sulfate, ammonium nitrate and
ammonium chloride compounds contributed to light-scattering fractions of
54, 24, 12 and 10%, respectively. This study indicated that
the organic component in submicron aerosol played an important role in
visibility degradation during the haze episode in Beijing. |
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