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| Titel |
Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City |
| VerfasserIn |
K. Adachi, P. R. Buseck |
| 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 ; 8, no. 21 ; Nr. 8, no. 21 (2008-11-13), S.6469-6481 |
| Datensatznummer |
250006441
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| Publikation (Nr.) |
 copernicus.org/acp-8-6469-2008.pdf |
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| Zusammenfassung |
| Soot particles, which are aggregated carbonaceous spherules with graphitic
structures, are major aerosol constituents that result from burning of
fossil fuel, biofuel, and biomass. Their properties commonly change through
reaction with other particles or gases, resulting in complex internal
mixtures. Using a transmission electron microscope (TEM) for both imaging
and chemical analysis, we measured ~8000 particles (25 samples) with
aerodynamic diameters from 0.05 to 0.3 μm that were collected in March
2006 from aircraft over Mexico City (MC) and adjacent areas. Most particles
are coated, consist of aggregates, or both. For example, almost all analyzed
particles contain S and 70% also contain K, suggesting coagulation and
condensation of sulfates and particles derived from biomass and biofuel
burning. In the MC plumes, over half of all particles contained soot coated
by organic matter and sulfates. The median value of the soot volume fraction
in such coated particles is about 15%. In contrast to the assumptions
used in many climate models, the soot particles did not become compact even
when coated. Moreover, about 80% by volume of the particles consisting of
organic matter with sulfate also contained soot, indicating the important
role of soot in the formation of secondary aerosol particles. Coatings on
soot particles can amplify their light absorption, and coagulation with
sulfates changes their hygroscopic properties, resulting in shorter
lifetimes. Through changes in their optical and hygroscopic properties,
internally mixed soot particles have a greater effect on the regional
climate of MC than uncoated soot particles. |
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