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| Titel |
Photochemical processing of organic aerosol at nearby continental sites: contrast between urban plumes and regional aerosol |
| VerfasserIn |
J. G. Slowik, J. Brook, R. Y.-W. Chang, G. J. Evans, K. Hayden, C.-H. Jeong, S.-M. Li, J. Liggio, P. S. K. Liu, M. McGuire, C. Mihele, S. Sjostedt, 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. 6 ; Nr. 11, no. 6 (2011-03-31), S.2991-3006 |
| Datensatznummer |
250009534
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| Publikation (Nr.) |
 copernicus.org/acp-11-2991-2011.pdf |
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| Zusammenfassung |
| As part of the BAQS-Met 2007 field campaign, Aerodyne time-of-flight aerosol
mass spectrometers (ToF-AMS) were deployed at two sites in southwestern
Ontario from 17 June to 11 July 2007. One instrument was located at Harrow,
ON, a rural, agriculture-dominated area approximately 40 km southeast of the
Detroit/Windsor/Windsor urban area and 5 km north of Lake Erie. The second
instrument was located at Bear Creek, ON, a rural site approximately 70 km northeast of the Harrow site and 50 km east of Detroit/Windsor. Positive
matrix factorization analysis of the combined organic mass spectral dataset
yields factors related to secondary organic aerosol (SOA), direct emissions,
and a factor tentatively attributed to the reactive uptake of isoprene
and/or condensation of its early generation reaction products. This is the
first application of PMF to simultaneous AMS measurements at different
sites, an approach which allows for self-consistent, direct comparison of
the datasets. Case studies are utilized to investigate processing of SOA
from (1) fresh emissions from Detroit/Windsor and (2) regional aerosol
during periods of inter-site flow. A strong correlation is observed between
SOA/excess CO and photochemical age as represented by the NOx/NOy
ratio for Detroit/Windsor outflow. Although this correlation is not evident
for more aged air, measurements at the two sites during inter-site transport
nevertheless show evidence of continued atmospheric processing by SOA
production. However, the rate of SOA production decreases with airmass age
from an initial value of ~10.1 μg m−3 ppmvCO−1 h−1 for the first ~10 h of plume processing to near-zero in an
aged airmass (i.e. after several days). The initial SOA production rate is
comparable to the observed rate in Mexico City over similar timescales. |
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