Gaye, B., Nagel, B., Dähnke, K., Rixen, Tim, Lahajnar, N. and Emeis, K.-C. (2013) Amino acid composition and δ15N of suspended matter in the Arabian Sea. Biogeosciences Discussions, 10 (8). pp. 7689-7702. DOI https://doi.org/10.5194/bgd-10-13317-2013.

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Abstract

Sedimentation in the ocean is fed by large aggre-gates produced in the surface mixed layer that sink rapidlythrough the water column. These particles sampled by sedi-ment traps have often been proposed to interact by disaggre-gation and scavenging with a pool of fine suspended matterwith very slow sinking velocities and thus a long residencetime. We investigated the amino acid (AA) composition andstable nitrogen isotopic ratios of suspended matter (SPM)sampled during the late SW monsoon season in the Ara-bian Sea and compared them to those of sinking particles tounderstand organic matter degradation/modification duringpassage through the water column. We found that AA com-position of mixed layer suspended matter corresponds moreto fresh plankton and their aggregates, whereas AA compo-sition of SPM in the sub-thermocline water column deviatedprogressively from mixed layer composition. We concludethat suspended matter in deep waters and in the mixed lay-ers of oligotrophic stations is dominated by fine material thathas a long residence time and organic matter that is resis-tant to degradation. SPM in areas of high primary productiv-ity is essentially derived from fresh plankton and thus has astrong imprint of the subsurface nitrate source, whereas SPMat oligotrophic stations and at subthermocline depths appearsto exchange amino acids and nitrogen isotopes with the dis-solved organic carbon (DOC) pool influencing also the δ15N values.

Document Type:	Article
Programme Area:	UNSPECIFIED
Research affiliation:	Biogeochemistry and Geology > Carbon and Nutrient Cycling
Refereed:	Yes
Open Access Journal?:	Yes
DOI:	https://doi.org/10.5194/bgd-10-13317-2013
ISSN:	1810-6285
Date Deposited:	16 Aug 2019 12:25
Last Modified:	26 Mar 2024 13:29
URI:	http://cris.leibniz-zmt.de/id/eprint/2638

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