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| Titel |
Surface gas pollutants in Lhasa, a highland city of Tibet – current levels and pollution implications |
| VerfasserIn |
L. Ran, W. L. Lin, Y. Z. Deji, B. La, P. M. Tsering, X. B. Xu, W. 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. 19 ; Nr. 14, no. 19 (2014-10-10), S.10721-10730 |
| Datensatznummer |
250119093
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| Publikation (Nr.) |
 copernicus.org/acp-14-10721-2014.pdf |
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| Zusammenfassung |
| Through several years of development, the city of Lhasa has become one of
the most populated and urbanized areas on the highest plateau in the world.
In the process of urbanization, current and potential air quality issues
have been gradually concerned. To investigate the current status of air
pollution in Lhasa, various gas pollutants including NOx, CO, SO2, and
O3, were continuously measured from June 2012 to May 2013 at an urban
site (29.40° N, 91.08° E, 3650 m a.s.l.). The seasonal
variations of primary gas pollutants exhibited a peak from November to
January with a large variability. High mixing ratios of primary trace gases
almost exclusively occurred under low wind speed and showed no distinct
dependence on wind direction, implying local urban emissions to be
predominant. A comparison of NO2, CO, and SO2 mixing ratios in
summer between 1998 and 2012 indicated a significant increase in emissions
of these gas pollutants and a change in their intercorrelations, as a result
of a substantial growth in the demand of energy consumption using fossil
fuels instead of previously widely used biomass. The pronounced diurnal
double peaks of primary trace gases in all seasons suggested automobile
exhaust to be a major emission source in Lhasa. The secondary gas pollutant
O3 displayed an average diurnal cycle of a shallow flat peak for about
4–5 h in the afternoon and a minimum in the early morning. Nighttime
O3 was sometimes completely consumed by the high level of NOx.
Seasonally, the variations of O3 mixing ratios displayed a low valley
in winter and a peak in spring. In autumn and winter, transport largely
contributed to the observed O3 mixing ratios, given its dependence on
wind speed and wind direction, while in spring and summer photochemistry
played an important role. A more efficient buildup of O3 mixing ratios
in the morning and a higher peak in the afternoon was found in summer 2012
than in 1998. An enhancement in O3 mixing ratios would be expected in
the future and more attention should be given to O3 photochemistry in
response to increasing precursor emissions in this area. |
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