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| Titel |
Size-resolved atmospheric particulate polysaccharides in the high summer Arctic |
| VerfasserIn |
C. Leck, Q. Gao, F. Mashayekhy Rad, U. Nilsson |
| 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 ; 13, no. 24 ; Nr. 13, no. 24 (2013-12-23), S.12573-12588 |
| Datensatznummer |
250085903
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| Publikation (Nr.) |
 copernicus.org/acp-13-12573-2013.pdf |
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| Zusammenfassung |
| Size-resolved aerosol samples for subsequent quantitative determination of
polymer sugars (polysaccharides) after hydrolysis to their subunit monomers
(monosaccharides) were collected in surface air over the central Arctic Ocean
during the biologically most active summer period. The analysis was carried
out by novel use of liquid chromatography coupled with highly selective and
sensitive tandem mass spectrometry. Polysaccharides were detected in particle
sizes ranging from 0.035 to 10 μm in diameter with distinct
features of heteropolysaccharides, enriched in xylose, glucose + mannose
as well as a substantial fraction of deoxysugars. Polysaccharides, containing
deoxysugar monomers, showed a bimodal size structure with about 70% of
their mass found in the Aitken mode over the pack ice area. Pentose (xylose)
and hexose (glucose + mannose) had a weaker bimodal character and were
largely found with super-micrometer sizes and in addition with a minor
sub-micrometer fraction. The concentration of total hydrolysable neutral
sugars (THNS) in the samples collected varied over two orders of magnitude
(1 to 160 pmol m−3) in the super-micrometer size fraction and to a
somewhat
lesser extent in sub-micrometer particles (4 to 140 pmol m−3). Lowest
THNS concentrations were observed in air masses that had spent more than five
days over the pack ice. Within the pack ice area, about 53% of the mass
of hydrolyzed polysaccharides was detected in sub-micrometer particles. The
relative abundance of sub-micrometer hydrolyzed polysaccharides could be
related to the length of time that the air mass spent over pack ice, with the
highest fraction (> 90%) observed for > 7 days
of advection. The aerosol samples collected onboard ship showed similar
monosaccharide composition, compared to particles generated experimentally in
situ at the expedition's open lead site. This supports the existence of a
primary particle source of polysaccharide containing polymer gels from open
leads by bubble bursting at the air–sea interface. We speculate that the
occurrence of atmospheric surface-active polymer gels with their hydrophilic
and hydrophobic segments, promoting cloud droplet activation, could play a
potential role as cloud condensation nuclei in the pristine high Arctic. |
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