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| Titel |
On the chemical dynamics of extracellular polysaccharides in the high Arctic surface microlayer |
| VerfasserIn |
Q. Gao, C. Leck, C. Rauschenberg, P. A. Matrai |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 8, no. 4 ; Nr. 8, no. 4 (2012-07-05), S.401-418 |
| Datensatznummer |
250005740
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| Publikation (Nr.) |
 copernicus.org/os-8-401-2012.pdf |
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| Zusammenfassung |
| The surface microlayer (SML) represents a unique system of which the
physicochemical characteristics may differ from those of the underlying
subsurface seawater (SSW). Within the Arctic pack ice area, the SML has been
characterized as enriched in small colloids of biological origin, resulting
from extracellular polymeric secretions (EPS). During the Arctic Summer
Cloud Ocean Study (ASCOS) in August 2008, particulate organic matter (POM,
with size range > 0.22 μm) and dissolved organic matter (DOM, < 0.22 μm,
obtained after filtration) samples were collected and
chemically characterized from the SML and the corresponding SSW at an open
lead centered at 87.5° N and 5° E. Total organic carbon was
persistently enriched in the SML with a mean enrichment factor (EF) of 1.45 ± 0.41,
whereas sporadic depletions of dissolved carbohydrates and
amino acids were observed. Monosaccharide compositional analysis reveals
that EPS in the Arctic lead was formed mainly of distinctive
heteropolysaccharides, enriched in xylose, fucose and glucose. The mean
concentrations of total hydrolysable neutral sugars in SSW were 94.9 ± 37.5
nM in high molecular weight (HMW) DOM (> 5 kDa) and 64.4 ± 14.5 nM
in POM. The enrichment of polysaccharides in the SML appeared to be a
common feature, with EFs ranging from 1.7 to 7.0 for particulate
polysaccharides and 3.5 to 12.1 for polysaccharides in the HMW DOM fraction.
A calculated monosaccharide yield suggests that polymers in the HMW DOM
fraction were scavenged, without substantial degradation, into the SML.
Bubble scavenging experiments showed that newly aggregated particles could
be formed abiotically by coagulation of low molecular weight nanometer-sized
gels. Aerosol particles, artificially generated by bubbling experiments,
were enriched in polysaccharides by factors of 22–70, relative to the source
seawater. We propose that bubble scavenging of surface-active
polysaccharides could be one of the possible mechanisms for the enrichment
of polysaccharides in the high Arctic open lead SML. |
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