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| Titel |
Characterization of the South Atlantic marine boundary layer aerosol using an aerodyne aerosol mass spectrometer |
| VerfasserIn |
S. R. Zorn, F. Drewnick, M. Schott, T. Hoffmann, S. Borrmann |
| 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. 16 ; Nr. 8, no. 16 (2008-08-18), S.4711-4728 |
| Datensatznummer |
250006328
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| Publikation (Nr.) |
 copernicus.org/acp-8-4711-2008.pdf |
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| Zusammenfassung |
Measurements of the submicron fraction of the atmospheric aerosol in
the marine boundary layer were performed from January to March 2007
(Southern Hemisphere summer) onboard the French research vessel
Marion Dufresne in the Southern Atlantic and Indian Ocean
(20° S–60° S, 70° W–60° E). We
used an Aerodyne High-Resolution-Time-of-Flight AMS to characterize
the chemical composition and to measure species-resolved size
distributions of non-refractory aerosol components in the submicron
range.
Within the "standard" AMS compounds (ammonium, chloride, nitrate,
sulfate, organics) "sulfate" is the dominant species in the marine
boundary layer with concentrations ranging between 50 ng m−3
and 3 μg m−3. Furthermore, what is seen as "sulfate" by
the AMS is likely comprised mostly of sulfuric acid.
Another sulfur containing species that is produced in marine
environments is methanesulfonic acid (MSA). There have been
previously measurements of MSA using an Aerodyne AMS. However, due
to the use of an instrument equipped with a quadrupole detector with
unit mass resolution it was not possible to physically separate MSA
from other contributions to the same m/z. In order to identify MSA
within the HR-ToF-AMS raw data and to extract mass concentrations
for MSA from the field measurements the standard high-resolution MSA
fragmentation patterns for the measurement conditions during the
ship campaign (e.g. vaporizer temperature) needed to be determined.
To identify characteristic air masses and their source regions
backwards trajectories were used and averaged concentrations for AMS
standard compounds were calculated for each air mass type. Sulfate
mass size distributions were measured for these periods showing a
distinct difference between oceanic air masses and those from
African outflow. While the peak in the mass distribution was roughly
at 250 nm (vacuum aerodynamic diameter) in marine air masses, it
was shifted to 470 nm in African outflow air. Correlations between
the mass concentrations of sulfate, organics and MSA show a narrow
correlation for MSA with sulfate/sulfuric acid coming from the
ocean, but not with continental sulfate. |
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