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| Titel |
Distribution, magnitudes, reactivities, ratios and diurnal patterns of volatile organic compounds in the Valley of Mexico during the MCMA 2002 & 2003 field campaigns |
| VerfasserIn |
E. Velasco, B. Lamb, H. Westberg, E. Allwine, G. Sosa, J. L. Arriaga-Colina, B. T. Jobson, M. L. Alexander, P. Prazeller, W. B. Knighton, T. M. Rogers, M. Grutter, S. C. Herndon, C. E. Kolb, M. Zavala, B. Foy, R. Volkamer, L. T. Molina, M. J. Molina |
| 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 ; 7, no. 2 ; Nr. 7, no. 2 (2007-01-23), S.329-353 |
| Datensatznummer |
250004462
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| Publikation (Nr.) |
 copernicus.org/acp-7-329-2007.pdf |
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| Zusammenfassung |
| A wide array of volatile organic compound (VOC) measurements was conducted
in the Valley of Mexico during the MCMA-2002 and 2003 field campaigns. Study
sites included locations in the urban core, in a heavily industrial area and
at boundary sites in rural landscapes. In addition, a novel
mobile-laboratory-based conditional sampling method was used to collect
samples dominated by fresh on-road vehicle exhaust to identify those VOCs
whose ambient concentrations were primarily due to vehicle emissions. Four
distinct analytical techniques were used: whole air canister samples with
Gas Chromatography/Flame Ionization Detection (GC-FID), on-line chemical
ionization using a Proton Transfer Reaction Mass Spectrometer (PTR-MS),
continuous real-time detection of olefins using a Fast Olefin Sensor (FOS),
and long path measurements using UV Differential Optical Absorption
Spectrometers (DOAS). The simultaneous use of these techniques provided a
wide range of individual VOC measurements with different spatial and
temporal scales. The VOC data were analyzed to understand concentration and
spatial distributions, diurnal patterns, origin and reactivity in the
atmosphere of Mexico City. The VOC burden (in ppbC) was dominated by alkanes
(60%), followed by aromatics (15%) and olefins (5%). The remaining
20% was a mix of alkynes, halogenated hydrocarbons, oxygenated species
(esters, ethers, etc.) and other unidentified VOCs. However, in terms of
ozone production, olefins were the most relevant hydrocarbons. Elevated
levels of toxic hydrocarbons, such as 1,3-butadiene, benzene, toluene and
xylenes, were also observed. Results from these various analytical
techniques showed that vehicle exhaust is the main source of VOCs in Mexico
City and that diurnal patterns depend on vehicular traffic in addition to
meteorological processes. Finally, examination of the VOC data in terms of
lumped modeling VOC classes and its comparison to the VOC lumped emissions
reported in other photochemical air quality modeling studies suggests that
some alkanes are underestimated in the emissions inventory, while some
olefins and aromatics are overestimated. |
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