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| Titel |
Sources and transformations of particle-bound polycyclic aromatic hydrocarbons in Mexico City |
| VerfasserIn |
L. C. Marr, K. Dzepina, J. L. Jimenez, F. Reisen, H. L. Bethel, J. Arey, J. S. Gaffney, N. A. Marley, 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 ; 6, no. 6 ; Nr. 6, no. 6 (2006-05-23), S.1733-1745 |
| Datensatznummer |
250003831
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| Publikation (Nr.) |
 copernicus.org/acp-6-1733-2006.pdf |
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| Zusammenfassung |
| Understanding sources, concentrations, and transformations of polycyclic
aromatic hydrocarbons (PAHs) in the atmosphere is important because of their
potent mutagenicity and carcinogenicity. The measurement of particle-bound
PAHs by three different methods during the Mexico City Metropolitan Area
field campaign in April 2003 presents a unique opportunity for
characterization of these compounds and intercomparison of the methods. The three
methods are (1) collection and analysis of bulk samples for time-integrated
gas- and particle-phase speciation by gas chromatography/mass spectrometry;
(2) aerosol photoionization for fast detection of PAHs on particles'
surfaces; and (3) aerosol mass spectrometry for fast analysis of size and
chemical composition. This research represents the first time aerosol mass
spectrometry has been used to measure ambient PAH concentrations and the
first time that fast, real-time methods have been used to quantify PAHs
alongside traditional filter-based measurements in an extended field
campaign. Speciated PAH measurements suggest that motor vehicles and garbage
and wood burning are important sources in Mexico City. The diurnal
concentration patterns captured by aerosol photoionization and aerosol mass
spectrometry are generally consistent. Ambient concentrations of particle-phase PAHs
typically peak at ~110 ng m-3 during the morning rush hour and rapidly
decay due to changes in source activity patterns and dilution as the boundary
layer rises, although surface-bound PAH concentrations decay faster. The
more rapid decrease in surface versus bulk PAH concentrations during the
late morning suggests that freshly emitted combustion-related particles are
quickly coated by secondary aerosol material in Mexico City's atmosphere and
may also be transformed by heterogeneous reactions. |
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