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| Titel |
Processing of soot in an urban environment: case study from the Mexico City Metropolitan Area |
| VerfasserIn |
K. S. Johnson, B. Zuberi, L. T. Molina, M. J. Molina, M. J. Iedema, J. P. Cowin, D. J. Gaspar, C. Wang, A. Laskin |
| 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 ; 5, no. 11 ; Nr. 5, no. 11 (2005-11-14), S.3033-3043 |
| Datensatznummer |
250003147
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| Publikation (Nr.) |
 copernicus.org/acp-5-3033-2005.pdf |
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| Zusammenfassung |
| Chemical composition, size, and mixing state of atmospheric particles are
critical in determining their effects on the environment. There is growing
evidence that soot aerosols play a particularly important role in both
climate and human health, but still relatively little is known of their
physical and chemical nature. In addition, the atmospheric residence times
and removal mechanisms for soot are neither well understood nor adequately
represented in regional and global climate models. To investigate the effect
of locality and residence time on properties of soot and mixing state in a
polluted urban environment, particles of diameter 0.2–2.0 μm were
collected in the Mexico City Metropolitan Area (MCMA) during the MCMA-2003
Field Campaign from various sites within the city. Individual particle
analysis by different electron microscopy methods coupled with energy
dispersed x-ray spectroscopy, and secondary ionization mass spectrometry
show that freshly-emitted soot particles become rapidly processed in the
MCMA. Whereas fresh particulate emissions from mixed-traffic are almost
entirely carbonaceous, consisting of soot aggregates with liquid coatings
suggestive of unburned lubricating oil and water, ambient soot particles
which have been processed for less than a few hours are heavily internally
mixed, primarily with ammonium sulfate. Single particle analysis suggests
that this mixing occurs through several mechanisms that require further
investigation. In light of previously published results, the
internally-mixed nature of processed soot particles is expected to affect
heterogeneous chemistry on the soot surface, including interaction with
water during wet-removal. |
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