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| Titel |
Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study |
| VerfasserIn |
J. A. Gouw, D. Welsh-Bon, C. Warneke, W. C. Kuster, L. Alexander, A. K. Baker, A. J. Beyersdorf, D. R. Blake, M. Canagaratna, A. T. Celada, L. G. Huey, W. Junkermann, T. B. Onasch, A. Salcido, S. J. Sjostedt, A. P. Sullivan, D. J. Tanner, O. Vargas, R. J. Weber, D. R. Worsnop, X. Y. Yu, R. Zaveri |
| 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. 10 ; Nr. 9, no. 10 (2009-05-28), S.3425-3442 |
| Datensatznummer |
250007311
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| Publikation (Nr.) |
 copernicus.org/acp-9-3425-2009.pdf |
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| Zusammenfassung |
| Volatile organic compounds (VOCs) and carbonaceous aerosol were measured at
a sub-urban site near Mexico City in March of 2006 during the MILAGRO study
(Megacity Initiative: Local and Global Research Objectives). Diurnal
variations of hydrocarbons, elemental carbon (EC) and hydrocarbon-like
organic aerosol (HOA) were dominated by a high peak in the early morning
when local emissions accumulated in a shallow boundary layer, and a minimum
in the afternoon when the emissions were diluted in a significantly expanded
boundary layer and, in case of the reactive gases, removed by OH. In
comparison, diurnal variations of species with secondary sources such as the
aldehydes, ketones, oxygenated organic aerosol (OOA) and water-soluble
organic carbon (WSOC) stayed relatively high in the afternoon indicating
strong photochemical formation. Emission ratios of many hydrocarbon species
relative to CO were higher in Mexico City than in the U.S., but we found
similar emission ratios for most oxygenated VOCs and organic aerosol.
Secondary formation of acetone may be more efficient in Mexico City than in
the U.S., due to higher emissions of alkane precursors from the use of
liquefied petroleum gas. Secondary formation of organic aerosol was similar
between Mexico City and the U.S. Combining the data for all measured gas and
aerosol species, we describe the budget of total observed organic carbon
(TOOC), and find that the enhancement ratio of TOOC relative to CO is
conserved between the early morning and mid afternoon despite large
compositional changes. Finally, the influence of biomass burning is
investigated using the measurements of acetonitrile, which was found to
correlate with levoglucosan in the particle phase. Diurnal variations of
acetonitrile indicate a contribution from local burning sources. Scatter
plots of acetonitrile versus CO suggest that the contribution of biomass
burning to the enhancement of most gas and aerosol species was not dominant
and perhaps not dissimilar from observations in the U.S. |
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