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| Titel |
Molecular composition of fresh and aged secondary organic aerosol from a mixture of biogenic volatile compounds: a high-resolution mass spectrometry study |
| VerfasserIn |
I. Kourtchev, J.-F. Doussin, C. Giorio, B. Mahon, E. M. Wilson, N. Maurin, E. Pangui, D. S. Venables, J. C. Wenger, M. Kalberer |
| 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. 10 ; Nr. 15, no. 10 (2015-05-26), S.5683-5695 |
| Datensatznummer |
250119749
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| Publikation (Nr.) |
 copernicus.org/acp-15-5683-2015.pdf |
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| Zusammenfassung |
| Field observations over the past decade indicate that a significant fraction
of organic aerosol in remote areas may contain highly oxidized molecules.
Aerosol processing or further oxidation (aging) of organic aerosol has been
suggested to be responsible for their formation through heterogeneous reaction with oxidants and multigenerational oxidation of vapours by OH radicals. In
this study we investigated the influence of several aging processes on the
molecular composition of secondary organic aerosols (SOA) using direct
infusion and liquid chromatography high-resolution mass spectrometry. SOA
was formed in simulation chamber experiments from ozonolysis of a mixture of
four biogenic volatile organic compounds (BVOC): α-pinene, β-pinene, Δ3-carene and isoprene. The SOA was subsequently aged
under three different sets of conditions: in the dark in the presence of
residual ozone, with UV irradiation and OH radicals, and using UV light
only. Among all studied conditions, only OH radical-initiated aging was
found to influence the molecular composition of the aerosol and showed an
increase in carbon oxidation state (OSC) and elemental O / C ratios of
the SOA components. None of the aging processes produced an observable
effect on the oligomers formed from ozonolysis of the BVOC mixture, which
were found to be equally abundant in both "fresh" and "aged" SOA. Additional
experiments using α-pinene as the sole precursor demonstrated that
oligomers are an important group of compounds in SOA produced from both
ozonolysis and OH radical-initiated oxidation processes; however, a
completely different set of oligomers is formed under these two oxidation
regimes. SOA from the OH-initiated oxidation of α-pinene had a
significantly higher overall OSC and O / C compared to that from pure
ozonolysis experiments confirming that the OH radical reaction is more
likely to be responsible for the occurrence of highly oxidized species in
ambient biogenic SOA. |
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