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| Titel |
Nocturnal isoprene oxidation over the Northeast United States in summer and its impact on reactive nitrogen partitioning and secondary organic aerosol |
| VerfasserIn |
S. S. Brown, J. A. deGouw, C. Warneke, T. B. Ryerson, W. P. Dubé, E. Atlas, R. J. Weber, R. E. Peltier, J. A. Neuman, J. M. Roberts, A. Swanson, F. Flocke, S. A. McKeen, J. Brioude, R. Sommariva, M. Trainer, F. C. Fehsenfeld, A. R. Ravishankara |
| 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 ; 9, no. 9 ; Nr. 9, no. 9 (2009-05-11), S.3027-3042 |
| Datensatznummer |
250007270
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| Publikation (Nr.) |
 copernicus.org/acp-9-3027-2009.pdf |
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| Zusammenfassung |
| Isoprene is the largest single VOC emission to the atmosphere. Although it
is primarily oxidized photochemically during daylight hours, late-day
emissions that remain in the atmosphere at sunset undergo oxidation by
NO3 in regionally polluted areas with large NOx levels. A recent
aircraft study examined isoprene and its nocturnal oxidants in a series of
night flights across the Northeast US, a region with large emissions of
both isoprene and NOx. Substantial amounts of isoprene that were
observed after dark were strongly anticorrelated with measured NO3 and
were the most important factor determining the lifetime of this radical. The
products of photochemical oxidation of isoprene, methyl vinyl ketone and
methacrolein, were more uniformly distributed, and served as tracers for the
presence of isoprene at sunset, prior to its oxidation by NO3.
A determination of the mass of isoprene oxidized in darkness showed it to
be a large fraction (>20%) of emitted isoprene. Organic nitrates
produced from the NO3+isoprene reaction, though not directly measured, were estimated to account
for 2–9% of total reactive nitrogen. The mass of isoprene oxidized by
NO3 was comparable to and correlated with the organic aerosol loading
for flights with relatively low organic aerosol background. The contribution
of nocturnal isoprene oxidation to secondary organic aerosol was determined
in the range 1–17%, and isoprene SOA mass derived from NO3 was
calculated to exceed that due to OH by approximately 50%. |
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