In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 7 ( 2021-04-08), p. 5463-5476
Abstract:
Abstract. Volatility and viscosity have substantial impacts on
gas–particle partitioning, formation and evolution of aerosol and hence the
predictions of aerosol-related air quality and climate effects. Here aerosol
volatility and viscosity at a rural site (Gucheng) and an urban site
(Beijing) in the North China Plain (NCP) in summer and winter were investigated
by using a thermodenuder coupled with a high-resolution aerosol mass
spectrometer. The effective saturation concentration (C*) of organic aerosol
(OA) in summer was smaller than that in winter (0.55 µg m−3 vs.
0.71–0.75 µg m−3), indicating that OA in winter in the NCP is more
volatile due to enhanced primary emissions from coal combustion and biomass
burning. The volatility distributions varied and were largely different among
different OA factors. In particular, we found that hydrocarbon-like OA (HOA)
contained more nonvolatile compounds compared to coal-combustion-related
OA. The more oxidized oxygenated OA (MO-OOA) showed overall lower volatility
than less oxidized OOA (LO-OOA) in both summer and winter, yet the
volatility of MO-OOA was found to be relative humidity (RH) dependent
showing more volatile properties at higher RH. Our results demonstrated the
different composition and chemical formation pathways of MO-OOA under
different RH levels. The glass transition temperature (Tg) and viscosity
of OA in summer and winter are estimated using the recently developed
parameterization formula. Our results showed that the Tg of OA in summer
in Beijing (291.5 K) was higher than that in winter (289.7–290.0 K), while
it varied greatly among different OA factors. The viscosity suggested that
OA existed mainly as solid in winter in Beijing (RH = 29 ± 17 %),
but as semisolids in Beijing in summer (RH = 48 ± 25 %) and
Gucheng in winter (RH = 68 ± 24 %). These results have the important
implication that kinetically limited gas–particle partitioning may need to
be considered when simulating secondary OA formation in the NCP.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-21-5463-2021
DOI:
10.5194/acp-21-5463-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
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