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| Titel |
Photochemical production of ozone in Beijing during the 2008 Olympic Games |
| VerfasserIn |
C. C.-K. Chou, C.-Y. Tsai, C.-C. Chang, P.-H. Lin, S. C. Liu, T. Zhu |
| 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. 18 ; Nr. 11, no. 18 (2011-09-23), S.9825-9837 |
| Datensatznummer |
250010098
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| Publikation (Nr.) |
 copernicus.org/acp-11-9825-2011.pdf |
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| Zusammenfassung |
| As a part of the CAREBeijing-2008 campaign, observations of O3, oxides
of nitrogen (NOx and NOy), CO, and hydrocarbons (NMHCs)
were carried out at the air quality observatory of the Peking University in
Beijing, China during August 2008, including the period of the 29th Summer
Olympic Games. The measurements were compared with those of the
CAREBeijing-2006 campaign to evaluate the effectiveness of the air pollution
control measures, which were conducted for improving the air quality in
Beijing during the Olympics. The results indicate that significant reduction
in the emissions of primary air pollutants had been achieved; the monthly
averaged mixing ratios of NOx, NOy, CO, and NMHCs decreased
by 42.2, 56.5, 27.8, and 49.7 %, respectively. In contrast to the primary
pollutants, the averaged mixing ratio of O3 increased by 42.2 %.
Nevertheless, it was revealed that the ambient levels of total oxidant
(Ox = O3+NO2+1.5 NOz) and NOz were
reduced by 21.3 and 77.4 %, respectively. The contradictions between
O3 and Ox were further examined in two case studies. Ozone
production rates of 30–70 ppbv h−1 and OPEx of ~8
mole mole−1 were observed on a clear-sky day in spite of the reduced
levels of precursors. In that case, it was found that the mixing ratio of
O3 increased with the increasing NO2/NO ratio, whereas the
NOz mixing ratio leveled off when NO2/NO>8. Consequently, the ratio of
O3 to NOz increased to above 10, indicating the shift from
VOC-sensitive regime to NOx-sensitive regime. However, in the other
case, it was found that the O3 production was inhibited significantly
due to substantial reduction in the NMHCs. According to the observations, it
was suggested that the O3 and/or Ox production rates in Beijing
should have been reduced as a result of the reduction in the emissions of
precursors during the Olympic period. However, the nighttime O3 levels
increased due to a decline in the NO-O3 titration, and the midday
O3 peak levels were elevated because of the shift in the photochemical
regime and the inhibition of NOz formation. |
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