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| Titel |
Using the chemical equilibrium partitioning space to explore factors influencing the phase distribution of compounds involved in secondary organic aerosol formation |
| VerfasserIn |
F. Wania, Y. D. Lei, C. Wang, J. P. D. Abbatt, K.-U. Goss |
| 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 (2015-03-27), S.3395-3412 |
| Datensatznummer |
250119579
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| Publikation (Nr.) |
 copernicus.org/acp-15-3395-2015.pdf |
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| Zusammenfassung |
| Many atmospheric and chemical variables influence the partitioning
equilibrium between gas phase and condensed phases of compounds implicated
in the formation of secondary organic aerosol (SOA). The large number of
factors and their interaction makes it often difficult to assess their
relative importance and concerted impact. Here we introduce a
two-dimensional space which maps regions of dominant atmospheric phase
distribution within a coordinate system defined by equilibrium partition
coefficients between the gas phase, an aqueous phase and a water-insoluble
organic matter (WIOM) phase. Placing compounds formed from the oxidation of
n-alkanes, terpenes and mono-aromatic hydrocarbons on the maps based on their
predicted partitioning properties allows for a simple graphical assessment
of their equilibrium phase distribution behaviour. Specifically, it allows
for the simultaneous visualisation and quantitative comparison of the impact
on phase distribution of changes in atmospheric parameters (such as
temperature, salinity, WIOM-phase polarity, organic aerosol load, and liquid
water content) and chemical properties (such as oxidation state, molecular
size, functionalisation, and dimerisation). The graphical analysis reveals
that the addition of hydroxyl, carbonyl and carboxyl groups increases the
affinity of aliphatic, alicyclic and aromatic hydrocarbons for the aqueous
phase more rapidly than their affinity for WIOM, suggesting that the aqueous
phase may often be relevant even for substances that are considerably larger
than the C2 and C3 compounds that are typically believed to be associated
with aqueous SOA. In particular, the maps identify some compounds that
contribute to SOA formation if partitioning to both WIOM and aqueous phase
is considered but would remain in the gas phase if either condensed phase
were neglected. For example, many semi-volatile α-pinene oxidation
products will contribute to aqueous SOA under the conditions of high liquid water content
encountered in clouds but would remain vapours in wet aerosol.
It is conceivable to develop parameterisations of "partitioning basis
sets" that group compounds with comparable partitioning properties, which – when combined with data on the abundance of those groups of compounds –
could serve in the simulation of SOA formation. |
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