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| Titel |
Secondary aerosol formation from photochemical aging of aircraft exhaust in a smog chamber |
| VerfasserIn |
M. A. Miracolo, C. J. Hennigan, M. Ranjan, N. T. Nguyen, T. D. Gordon, E. M. Lipsky, A. A. Presto, N. M. Donahue, 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. 9 ; Nr. 11, no. 9 (2011-05-05), S.4135-4147 |
| Datensatznummer |
250009694
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| Publikation (Nr.) |
 copernicus.org/acp-11-4135-2011.pdf |
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| Zusammenfassung |
| Field experiments were performed to investigate the effects of
photo-oxidation on fine particle emissions from an in-use CFM56-2B gas
turbine engine mounted on a KC-135 Stratotanker airframe. Emissions were
sampled into a portable smog chamber from a rake inlet installed one-meter
downstream of the engine exit plane of a parked and chocked aircraft. The
chamber was then exposed to sunlight and/or UV lights to initiate
photo-oxidation. Separate tests were performed at different engine loads (4,
7, 30, 85 %). Photo-oxidation created substantial secondary particulate
matter (PM), greatly exceeding the direct PM emissions at each engine load
after an hour or less of aging at typical summertime conditions. After
several hours of photo-oxidation, the ratio of secondary-to-primary PM mass
was on average 35 ± 4.1, 17 ± 2.5, 60 ± 2.2, and 2.7 ± 1.1
for the 4, 7, 30, and 85 % load experiments,
respectively. The composition of secondary PM formed strongly depended on
load. At 4 % load, secondary PM was dominated by secondary organic aerosol
(SOA). At higher loads, the secondary PM was mainly secondary sulfate. A
traditional SOA model that accounts for SOA formation from single-ring
aromatics and other volatile organic compounds underpredicts the measured
SOA formation by
~60 % at 4 % load and ~40 % at 85 %
load. Large amounts of lower-volatiliy organic vapors were
measured in the exhaust; they represent a significant pool of SOA precursors
that are not included in traditional SOA models. These results underscore
the importance of accounting for atmospheric processing when assessing the
influence of aircraft emissions on ambient PM levels. Models that do not
account for this processing will likely underpredict the contribution of
aircraft emissions to local and regional air pollution. |
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