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| Titel |
The impacts of precursor reduction and meteorology on ground-level ozone in the Greater Toronto Area |
| VerfasserIn |
S. C. Pugliese, J. G. Murphy, J. A. Geddes, J. M. Wang |
| 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 ; 14, no. 15 ; Nr. 14, no. 15 (2014-08-15), S.8197-8207 |
| Datensatznummer |
250118951
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| Publikation (Nr.) |
 copernicus.org/acp-14-8197-2014.pdf |
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| Zusammenfassung |
| Tropospheric ozone (O3) is a major component of photochemical smog and
is a known human health hazard, as well as a damaging factor for vegetation.
Its precursor compounds, nitrogen oxides (NOx) and volatile organic
compounds (VOCs), have a variety of anthropogenic and biogenic sources and
exhibit non-linear effects on ozone production. As an update to previous
studies on ground-level ozone in the Greater Toronto Area (GTA), we present
an analysis of NO2, VOC and O3 data from federal and provincial
governmental monitoring sites in the GTA from 2000 to 2012. We show that, over
the study period, summertime 24 h VOC reactivity and NO2 midday
(11:00–15:00) concentrations at all sites decreased significantly; since
2000, all sites experienced a decrease in NO2 of 28–62% and in
measured VOC reactivity of at least 53–71%. Comparing 2002–2003 to
2011–2012, the summed reactivity of OH towards NO2 and a suite of
measured VOCs decreased from 8.6 to 4.6 s−1. Ratios of reactive
VOC pairs indicate that the effective OH concentration experienced by
primary pollutants in the GTA has increased significantly over the study
period. Despite the continuous decrease in precursor levels, ozone
concentrations are not following the same pattern at all stations; it was
found that the Canada-wide Standard for ozone continues to be exceeded at
all monitoring stations. Additionally, while the years 2008–2011 had
consistently lower ozone levels than previous years, 2012 experienced one of
the highest recorded summertime ozone concentrations and a large number of
smog episodes. We demonstrate that these high ozone observations in 2012 may
be a result of the number of days with high solar radiation, the number of
stagnant periods and the transport of high ozone levels from upwind regions. |
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