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| Titel |
Emissions of volatile organic compounds inferred from airborne flux measurements over a megacity |
| VerfasserIn |
T. Karl, E. Apel, A. Hodzic, D. D. Riemer, D. R. Blake, C. Wiedinmyer |
| 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 ; 9, no. 1 ; Nr. 9, no. 1 (2009-01-14), S.271-285 |
| Datensatznummer |
250006645
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| Publikation (Nr.) |
 copernicus.org/acp-9-271-2009.pdf |
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| Zusammenfassung |
| Toluene and benzene are used for assessing the ability to measure
disjunct eddy covariance (DEC) fluxes of Volatile Organic Compounds (VOC)
using Proton Transfer Reaction Mass Spectrometry (PTR-MS) on aircraft.
Statistically significant correlation between vertical wind speed and mixing
ratios suggests that airborne VOC eddy covariance (EC) flux measurements
using PTR-MS are feasible. City-median midday toluene and benzene fluxes are
calculated to be on the order of 14.1±4.0 mg/m2/h and 4.7±2.3 mg/m2/h,
respectively. For comparison the adjusted CAM2004 emission
inventory estimates toluene fluxes of 10 mg/m2/h along the footprint of
the flight-track. Wavelet analysis of instantaneous toluene and benzene
measurements during city overpasses is tested as a tool to assess surface
emission heterogeneity. High toluene to benzene flux ratios above an
industrial district (e.g. 10–15 g/g) including the International airport
(e.g. 3–5 g/g) and a mean flux (concentration) ratio of 3.2±0.5 g/g
(3.9±0.3 g/g) across Mexico City indicate that evaporative fuel and
industrial emissions play an important role for the prevalence of aromatic
compounds. Based on a tracer model, which was constrained by BTEX (BTEX–
Benzene/Toluene/Ethylbenzene/m, p, o-Xylenes) compound
concentration ratios, the fuel marker methyl-tertiary-butyl-ether (MTBE) and
the biomass burning marker acetonitrile (CH3CN), we show that a
combination of industrial, evaporative fuel, and exhaust emissions account
for >87% of all BTEX sources. Our observations suggest that biomass
burning emissions play a minor role for the abundance of BTEX compounds in
the MCMA (2–13%). |
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