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| Titel |
Secondary organic aerosol formation in cloud droplets and aqueous particles (aqSOA): a review of laboratory, field and model studies |
| VerfasserIn |
B. Ervens, B. J. Turpin, R. J. Weber |
| 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 ; 11, no. 21 ; Nr. 11, no. 21 (2011-11-09), S.11069-11102 |
| Datensatznummer |
250010176
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| Publikation (Nr.) |
 copernicus.org/acp-11-11069-2011.pdf |
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| Zusammenfassung |
Progress has been made over the past decade in predicting secondary organic
aerosol (SOA) mass in the atmosphere using vapor pressure-driven
partitioning, which implies that SOA compounds are formed in the gas phase
and then partition to an organic phase (gasSOA). However, discrepancies in
predicting organic aerosol oxidation state, size and product (molecular
mass) distribution, relative humidity (RH) dependence, color, and vertical
profile suggest that additional SOA sources and aging processes may be
important. The formation of SOA in cloud and aerosol water (aqSOA) is not
considered in these models even though water is an abundant medium for
atmospheric chemistry and such chemistry can form dicarboxylic acids and
"humic-like substances" (oligomers, high-molecular-weight compounds), i.e.
compounds that do not have any gas phase sources but comprise a significant fraction
of the total SOA mass. There is direct evidence from field observations and
laboratory studies that organic aerosol is formed in cloud and aerosol
water, contributing substantial mass to the droplet mode.
This review summarizes the current knowledge on aqueous phase organic
reactions and combines evidence that points to a significant role of aqSOA
formation in the atmosphere. Model studies are discussed that explore the
importance of aqSOA formation and suggestions for model improvements are
made based on the comprehensive set of laboratory data presented here. A
first comparison is made between aqSOA and gasSOA yields and mass
predictions for selected conditions. These simulations suggest that aqSOA
might contribute almost as much mass as gasSOA to the SOA budget, with
highest contributions from biogenic emissions of volatile organic compounds
(VOC) in the presence of anthropogenic pollutants (i.e. NOx) at high
relative humidity and cloudiness. Gaps in the current understanding of aqSOA
processes are discussed and further studies (laboratory, field, model) are
outlined to complement current data sets. |
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