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| Titel |
Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol |
| VerfasserIn |
A. Asa-Awuku, A. P. Sullivan, C. J. Hennigan, R. J. Weber, A. Nenes |
| 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 ; 8, no. 4 ; Nr. 8, no. 4 (2008-02-18), S.799-812 |
| Datensatznummer |
250005668
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| Publikation (Nr.) |
 copernicus.org/acp-8-799-2008.pdf |
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| Zusammenfassung |
| In this study, we characterize the CCN activity of the water-soluble
organics in biomass burning aerosol. The aerosol after collection upon
filters is dissolved in water using sonication. Hydrophobic and hydrophilic
components are fractionated from a portion of the original sample using
solid phase extraction, and subsequently desalted. The surface tension and
CCN activity of these different samples are measured with a KSV CAM 200
goniometer and a DMT Streamwise Thermal Gradient CCN Counter, respectively.
The measurements show that the strongest surfactants are isolated in the
hydrophobic fraction, while the hydrophilics exhibit negligible surface
tension depression. The presence of salts (primarily
(NH4)2SO4) in the hydrophobic fraction substantially enhances
surface tension depression; their synergistic effects considerably enhance
CCN activity, exceeding that of pure (NH4)2SO4. From our
analysis, average thermodynamic properties (i.e, molar volume) are
determined for samples using our newly developed Köhler Theory Analysis
(KTA) method. The molar mass of the hydrophilic and
hydrophobic aerosol components is estimated to be 87±26 g mol−1
and 780±231 g mol−1, respectively. KTA also suggests that the
relative proportion (in moles) of hydrophobic to hydrophilic compounds in
the original sample to be 1:3. For the first time, KTA is applied to an
aerosol with this level of complexity and displays its potential for
providing physically-based constraints for GCM parameterizations of the
aerosol indirect effect. |
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