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| Titel |
Diurnally resolved particulate and VOC measurements at a rural site: indication of significant biogenic secondary organic aerosol formation |
| VerfasserIn |
S. J. Sjostedt, J. G. Slowik, J. R. Brook, R. Y.-W. Chang, C. Mihele, C. A. Stroud, A. Vlasenko, J. P. D. Abbatt |
| 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. 12 ; Nr. 11, no. 12 (2011-06-21), S.5745-5760 |
| Datensatznummer |
250009856
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| Publikation (Nr.) |
 copernicus.org/acp-11-5745-2011.pdf |
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| Zusammenfassung |
| We report simultaneous measurements of volatile organic compound (VOC)
mixing ratios including C6 to C8 aromatics, isoprene,
monoterpenes, acetone and organic aerosol mass loadings at a rural location
in southwestern Ontario, Canada by Proton-Transfer-Reaction Mass
Spectrometry (PTR-MS) and Aerosol Mass Spectrometry (AMS), respectively.
During the three-week-long Border Air Quality and Meteorology Study in
June–July 2007, air was sampled from a range of sources, including aged air
from the polluted US Midwest, direct outflow from Detroit 50 km away, and
clean air with higher biogenic input. After normalization to the diurnal
profile of CO, a long-lived tracer, diurnal analyses show clear
photochemical loss of reactive aromatics and production of oxygenated VOCs
and secondary organic aerosol (SOA) during the daytime. Biogenic VOC mixing
ratios increase during the daytime in accord with their light- and
temperature-dependent sources. Long-lived species, such as hydrocarbon-like
organic aerosol and benzene show little to no photochemical reactivity on
this timescale. From the normalized diurnal profiles of VOCs, an estimate of
OH concentrations during the daytime, measured O3 concentrations, and
laboratory SOA yields, we calculate integrated local organic aerosol
production amounts associated with each measured SOA precursor. Under the
assumption that biogenic precursors are uniformly distributed across the
southwestern Ontario location, we conclude that such precursors contribute
significantly to the total amount of SOA formation, even during the period
of Detroit outflow. The importance of aromatic precursors is more difficult
to assess given that their sources are likely to be localized and thus of
variable impact at the sampling location. |
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