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| Titel |
Predicting the relative humidities of liquid-liquid phase separation, efflorescence, and deliquescence of mixed particles of ammonium sulfate, organic material, and water using the organic-to-sulfate mass ratio of the particle and the oxygen-to-carbon elemental ratio of the organic component |
| VerfasserIn |
A. K. Bertram, S. T. Martin, S. J. Hanna, M. L. Smith, A. Bodsworth, Q. Chen, M. Kuwata, A. Liu, Y. You, S. R. Zorn |
| 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 (2011-11-07), S.10995-11006 |
| Datensatznummer |
250010171
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| Publikation (Nr.) |
 copernicus.org/acp-11-10995-2011.pdf |
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| Zusammenfassung |
| Individual particles that on a mass basis consist dominantly of the
components ammonium sulfate, oxygenated organic material, and water are a common class
of submicron particles found in today's atmosphere. Here we use (1) the
organic-to-sulfate (org:sulf) mass ratio of the overall particle and (2) the
oxygen-to-carbon (O:C) elemental ratio of the organic component as input
variables in parameterisations that predict the critical relative humidity of
several different types of particle phase transitions. Specifically these variables were
used to predict the critical relative humidity of liquid-liquid phase separation (SRH),
efflorescence (ERH), and deliquescence (DRH). Experiments were conducted by optical microscopy for 11
different oxygenated organic-ammonium sulfate systems covering the range 0.1< org:sulf <12.8 and 0.29 < O:C < 1.33.
These new data, in conjunction with other data already available in the
literature, were used to develop the parameterisations SRH(org:sulf, O:C),
ERH(org:sulf, O:C), and DRH(org:sulf, O:C). The parameterisations correctly
predicted SRH within 15% RH for 88% of the measurements, ERH within 5% for
84% of the measurements, and DRH within 5% for 94% of the measurements.
The applicability of the derived parameterisations beyond the training data
set was tested against observations for organic-sulfate particles produced in
an environmental chamber. The organic component consisted of secondary
organic material produced by the oxidation of isoprene,
α-pinene, and β-caryophyllene. The predictions of the
parameterisations were also tested against data from the Southern Great
Plains, Oklahoma, USA. The observed ERH and DRH values for both the chamber
and field data agreed within 5% RH with the values predicted by the
parameterisations using the measured org:sulf and O:C ratios as the input
variables. |
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