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| Titel |
Microscopic characterization of carbonaceous aerosol particle aging in the outflow from Mexico City |
| VerfasserIn |
R. C. Moffet, T. R. Henn, A. V. Tivanski, R. J. Hopkins, Y. Desyaterik, A. L. D. Kilcoyne, T. Tyliszczak, J. Fast, J. Barnard, V. Shutthanandan, S. S. Cliff, K. D. Perry, A. Laskin, M. K. Gilles |
| 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 ; 10, no. 3 ; Nr. 10, no. 3 (2010-02-01), S.961-976 |
| Datensatznummer |
250008024
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| Publikation (Nr.) |
 copernicus.org/acp-10-961-2010.pdf |
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| Zusammenfassung |
| This study was part of the Megacities Initiative: Local and Global Research
Observations (MILAGRO) field campaign conducted in Mexico City metropolitan
area during spring 2006. The physical and chemical transformations of
particles aged in the outflow from Mexico City were investigated for the
transport event of 22 March 2006. A detailed chemical analysis of individual
particles was performed using a combination of complementary microscopy and
micro-spectroscopy techniques. The applied techniques included scanning
transmission X-ray microscopy (STXM) coupled with near edge X-ray absorption
fine structure spectroscopy (NEXAFS) and computer controlled scanning
electron microscopy with an energy dispersive X-ray analyzer (CCSEM/EDX). As
the aerosol plume evolves from the city center, the organic mass per
particle increases and the fraction of carbon-carbon double bonds
(associated with elemental carbon) decreases. Organic functional groups
enhanced with particle age include: carboxylic acids, alkyl groups, and
oxygen bonded alkyl groups. At the city center (T0) the most prevalent
aerosol type contained inorganic species (composed of sulfur, nitrogen,
oxygen, and potassium) coated with organic material. At the T1 and T2 sites,
located northeast of T0 (~29 km and ~65 km, respectively), the
fraction of homogenously mixed organic particles increased in both size and
number. These observations illustrate the evolution of the physical mixing
state and organic bonding in individual particles in a photochemically
active environment. |
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