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| Titel |
Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of Cloud Condensation Nuclei (CCN) |
| VerfasserIn |
M. Kuwata, W. Shao, R. Lebouteiller, S. T. Martin |
| 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 ; 13, no. 10 ; Nr. 13, no. 10 (2013-05-27), S.5309-5324 |
| Datensatznummer |
250018673
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| Publikation (Nr.) |
 copernicus.org/acp-13-5309-2013.pdf |
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| Zusammenfassung |
| The governing highly soluble, slightly soluble, or insoluble activation
regime of organic compounds as cloud condensation nuclei (CCN) was examined
as a function of oxygen-to-carbon elemental ratio (O : C). New data were
collected for adipic, pimelic, suberic, azelaic, and pinonic acids.
Secondary organic materials (SOMs) produced by α-pinene ozonolysis
and isoprene photo-oxidation were also included in the analysis. The
saturation concentrations C of the organic compounds in aqueous solutions
served as the key parameter for delineating regimes of CCN activation, and
the values of C were tightly correlated to the O : C ratios. The highly
soluble, slightly soluble, and insoluble regimes of CCN activation were
found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C]
< 0.6, and [O : C] < 0.2, respectively. These classifications
were evaluated against CCN activation data of isoprene-derived SOM (O : C =
0.69–0.72) and α-pinene-derived SOM (O : C = 0.38–0.48).
Isoprene-derived SOM had highly soluble activation behavior, consistent with
its high O : C ratio. For α-pinene-derived SOM, although CCN
activation can be modeled as a highly soluble mechanism, this behavior was
not predicted by the O : C ratio, for which a slightly soluble mechanism was
anticipated. Complexity in chemical composition, resulting in continuous
water uptake and the absence of a deliquescence transition that can
thermodynamically limit CCN activation, might explain the difference in the
behavior of α-pinene-derived SOM compared to that of pure organic
compounds. The present results suggest that atmospheric particles dominated
by hydrocarbon-like organic components do not activate (i.e., insoluble
regime) whereas those dominated by oxygenated organic components activate
(i.e., highly soluble regime) for typical atmospheric cloud life cycles. |
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