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| Titel |
A molecular perspective on the ageing of marine dissolved organic matter |
| VerfasserIn |
R. Flerus, O. J. Lechtenfeld, B. P. Koch, S. L. McCallister, P. Schmitt-Kopplin, R. Benner, K. Kaiser, G. Kattner |
| 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 ; 9, no. 6 ; Nr. 9, no. 6 (2012-06-01), S.1935-1955 |
| Datensatznummer |
250007110
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| Publikation (Nr.) |
 copernicus.org/bg-9-1935-2012.pdf |
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| Zusammenfassung |
| Dissolved organic matter (DOM) was extracted by solid-phase extraction (SPE)
from 137 water samples from different climate zones and different depths
along an eastern Atlantic Ocean transect. The extracts were analyzed with
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with
electrospray ionization (ESI). Δ14C analyses were performed on
subsamples of the SPE-DOM. In addition, the amount of dissolved organic
carbon was determined for all water and SPE-DOM samples as well as the yield
of amino sugars for selected samples. Linear correlations were observed
between the magnitudes of 43 % of the FT-ICR mass peaks and the extract
Δ14C values. Decreasing SPE-DOM Δ14C values went
along with a shift in the molecular composition to higher average masses
(m/z) and lower hydrogen/carbon (H/C) ratios. The correlation was used to
model the SPE-DOM Δ14C distribution for all 137 samples. Based
on single mass peaks, a degradation index (IDEG) was developed to
compare the degradation state of marine SPE-DOM samples analyzed with FT-ICR
MS. A correlation between Δ14C, IDEG, DOC values and amino
sugar yield supports that SPE-DOM analyzed with FT-ICR MS reflects trends of
bulk DOM. DOM weighted normalized mass peak magnitudes were used to compare
aged and recent SPE-DOM on a semi-quantitative molecular basis. The magnitude comparison showed a continuum of different degradation
rates for the detected compounds. A high proportion of the compounds should
persist, possibly modified by partial degradation, in the course of thermohaline
circulation. Prokaryotic (bacterial) production, transformation and
accumulation of this very stable DOM occur primarily in the upper
ocean. This DOM is an important contribution to very old DOM, showing that
production and degradation are dynamic processes. |
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