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| Titel |
Formaldehyde and its relation to CO, PAN, and SO2 in the Houston-Galveston airshed |
| VerfasserIn |
B. Rappenglück, P. K. Dasgupta, M. Leuchner, Q. Li, W. Luke |
| 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 ; 10, no. 5 ; Nr. 10, no. 5 (2010-03-09), S.2413-2424 |
| Datensatznummer |
250008177
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| Publikation (Nr.) |
 copernicus.org/acp-10-2413-2010.pdf |
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| Zusammenfassung |
The Houston-Galveston Airshed (HGA) is one of the major metropolitan areas in
the US that is classified as a nonattainment area of federal ozone standards.
Formaldehyde (HCHO) is a key species in understanding ozone related
air pollution; some of the highest HCHO concentrations in North America have
been reported for the HGA. We report on HCHO measurements in the HGA from
summer 2006. Among several sites, maximum HCHO mixing ratios were observed in
the Houston Ship Channel (HSC), a region with a very high density of
industrial/petrochemical operations.
HCHO levels at the Moody Tower (MT) site close to downtown were dependent on
the wind direction: southerly maritime winds brought in background levels
(0.5–1 ppbv) while trajectories originating in the HSC resulted in high
HCHO (up to 31.5 ppbv). Based on the best multiparametric linear regression
model fit, the HCHO levels at the MT site can be accounted for as follows:
38.5±12.3% from primary vehicular emissions (using CO as an index of
vehicular emission), 24.1±17.7% formed photochemically (using
peroxyacetic nitric anhydride (PAN) as an index of photochemical activity)
and 8.9±11.2% from industrial emissions (using SO2 as an index of
industrial emissions). The balance 28.5±12.7% constituted the residual
which cannot be easily ascribed to the above categories and/or which is
transported into the HGA. The CO related HCHO fraction is dominant during the
morning rush hour (06:00–09:00 h, all times are given in CDT); on a carbon
basis, HCHO emissions are up to 0.7% of the CO emissions. The SO2 related
HCHO fraction is significant between 09:00–12:00 h. After 12:00 h HCHO is
largely formed through secondary processes. The HCHO/PAN ratios are dependent
on the SO2 levels. The SO2 related HCHO fraction at the downtown site
originates in the ship channel. Aside from traffic-related primary HCHO
emissions, HCHO of industrial origin serves as an appreciable source for OH
in the morning. |
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