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| Titel |
Amino acid composition and δ15N of suspended matter in the Arabian Sea: implications for organic matter sources and degradation |
| VerfasserIn |
B. Gaye, B. Nagel, K. Dähnke, T. Rixen, N. Lahajnar, K.-C. Emeis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 11 ; Nr. 10, no. 11 (2013-11-27), S.7689-7702 |
| Datensatznummer |
250085443
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| Publikation (Nr.) |
 copernicus.org/bg-10-7689-2013.pdf |
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| Zusammenfassung |
| Sedimentation in the ocean is fed by large aggregates produced in the surface
mixed layer that sink rapidly through the water column. These particles
sampled by sediment traps have often been proposed to interact by
disaggregation and scavenging with a pool of fine suspended matter with very
slow sinking velocities and thus a long residence time. We investigated the
amino acid (AA) composition and stable nitrogen isotopic ratios of suspended
matter (SPM) sampled during the late SW monsoon season in the Arabian Sea and
compared them to those of sinking particles to understand organic matter
degradation/modification during passage through the water column. We found
that AA composition of mixed layer suspended matter corresponds more to fresh
plankton and their aggregates, whereas AA composition of SPM in the
sub-thermocline water column deviated progressively from mixed layer
composition. We conclude that suspended matter in deep waters and in the
mixed layers of oligotrophic stations is dominated by fine material that has
a long residence time and organic matter that is resistant to degradation.
SPM in areas of high primary productivity is essentially derived from fresh
plankton and thus has a strong imprint of the subsurface nitrate source,
whereas SPM at oligotrophic stations and at subthermocline depths appears to
exchange amino acids and nitrogen isotopes with the dissolved organic carbon
(DOC) pool influencing also the δ15N values. |
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