 |
| Titel |
Composition and mixing state of wet season fine mode aerosol collected in the Amazonian tropical rain forest (Manaus, Brazil) |
| VerfasserIn |
B. W. Sinha, J. Huth, P. Hoppe, A. Snee-Pollmann, S. M. King, E. Mikhailov, U. Pöschl, M. O. Andreae, S. T. Martin |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023248
|
|
|
|
|
|
| Zusammenfassung |
| Single particle analysis of aerosol particles was performed on samples collected in the
tropical rain forest (Manaus, Brazil) during the AMAZE campaign in February and March
2008. During wet season, Amazonia is one of the few places on Earth where natural
continental aerosol, unperturbed by anthropogenic influences, can be investigated. Elemental
composition, morphology and mixing states of aerosol particles were determined using
SEM-EDX. Individual particles were also investigated using NanoSIMS. The particle number
distribution is dominated by droplets of organic aerosol (OA) and shows a pronounced
Hoppel gap separating the Aitken and accumulation mode. The Hoppel gap is believed to
differentiate those particles that have been subjected to in-cloud processing from those that
have not. We observe that all Aitken mode particles are pure droplets of organic
aerosol (OA), while 10 - 50% of organic droplets in the accumulation mode are
mixed with inorganic salts, indicating that wet processing plays an important role
in the formation of large organic aerosol droplets. Wet processing also leads to
organic coatings on all other particle classes observed. The frequency of organic
coatings depends strongly on the CCN activity of the particles involved. Less than
2% of the mineral dust particles show organic coatings. Whereas more than 35%
of all solid organic matter (and/or soot particles), more than 50% of all primary
biogenic particles, and 80% of all inorganic salt particles are coated with organics.
Even though combined SEM/EDX/NanoSIMS analysis does not allow speciation of
the organic carbon involved, it provides valuable insight into the mixing state of
pristine continental aerosol particles and allows investigating the implications for the
hygroscopic behavior, cloud activation properties, and the optical properties of
particles. |
|
|
|
|
|
|