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| Titel |
Chemical and physical transformations of organic aerosol from the photo-oxidation of open biomass burning emissions in an environmental chamber |
| VerfasserIn |
C. J. Hennigan, M. A. Miracolo, G. J. Engelhart, A. A. May, A. A. Presto, T. Lee, A. P. Sullivan, G. R. McMeeking, H. Coe, C. E. Wold, W.-M. Hao, J. B. Gilman, W. C. Kuster, J. Gouw, B. A. Schichtel, J. L. Collett, S. M. Kreidenweis, A. L. Robinson |
| 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. 15 ; Nr. 11, no. 15 (2011-08-01), S.7669-7686 |
| Datensatznummer |
250009968
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| Publikation (Nr.) |
 copernicus.org/acp-11-7669-2011.pdf |
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| Zusammenfassung |
| Smog chamber experiments were conducted to investigate the chemical and
physical transformations of organic aerosol (OA) during photo-oxidation of
open biomass burning emissions. The experiments were carried out at the US
Forest Service Fire Science Laboratory as part of the third Fire Lab at
Missoula Experiment (FLAME III). We investigated emissions from 12 different
fuels commonly burned in North American wildfires. The experiments feature
atmospheric and plume aerosol and oxidant concentrations; aging times ranged
from 3 to 4.5 h. OA production, expressed as a mass enhancement ratio
(ratio of OA to primary OA (POA) mass), was highly variable. OA mass
enhancement ratios ranged from 2.9 in experiments where secondary OA (SOA)
production nearly tripled the POA concentration to 0.7 in experiments where
photo-oxidation resulted in a 30 % loss of the OA mass. The
campaign-average OA mass enhancement ratio was 1.7 ± 0.7 (mean ± 1σ);
therefore, on average, there was substantial SOA production. In
every experiment, the OA was chemically transformed. Even in experiments
with net loss of OA mass, the OA became increasingly oxygenated and less
volatile with aging, indicating that photo-oxidation transformed the POA
emissions. Levoglucosan concentrations were also substantially reduced with
photo-oxidation. The transformations of POA were extensive; using
levoglucosan as a tracer for POA, unreacted POA only contributed 17 % of
the campaign-average OA mass after 3.5 h of exposure to typical
atmospheric hydroxyl radical (OH) levels. Heterogeneous reactions with OH
could account for less than half of this transformation, implying that the
coupled gas-particle partitioning and reaction of semi-volatile vapors is an
important and potentially dominant mechanism for POA processing. Overall,
the results illustrate that biomass burning emissions are subject to
extensive chemical processing in the atmosphere, and the timescale for these
transformations is rapid. |
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