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| Titel |
Water column distribution and carbon isotopic signal of cholesterol, brassicasterol and particulate organic carbon in the Atlantic sector of the Southern Ocean |
| VerfasserIn |
A.-J. Cavagna, F. Dehairs, S. Bouillon, V. Woule-Ebongué, F. Planchon, B. Delille, I. Bouloubassi |
| 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. 4 ; Nr. 10, no. 4 (2013-04-29), S.2787-2801 |
| Datensatznummer |
250018221
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| Publikation (Nr.) |
 copernicus.org/bg-10-2787-2013.pdf |
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| Zusammenfassung |
The combination of concentrations and δ13C signatures of
Particulate Organic Carbon (POC) and sterols provides a powerful approach to
study ecological and environmental changes in both the modern and ancient
ocean. We applied this tool to study the biogeochemical changes in the
modern ocean water column during the BONUS-GoodHope survey (February–March 2008)
from Cape Basin to the northern part of the Weddell Gyre. Cholesterol and
brassicasterol were chosen as ideal biomarkers of the heterotrophic and
autotrophic carbon pools, respectively, because of their ubiquitous and
relatively refractory nature.
We document depth distributions of concentrations (relative to bulk POC) and
δ13C signatures of cholesterol and brassicasterol combined with
CO2 aq. surface concentration variation. While the relationship between
CO2 aq. and δ13C of bulk POC and biomarkers have been
reported by others for the surface water, our data show that this persists
in mesopelagic and deep waters, suggesting that δ13C signatures
of certain biomarkers in the water column could be applied as proxies for
surface water CO2 aq. We observed a general increase in sterol
δ13C signatures with depth, which is likely related to a combination of
particle size effects, selective feeding on larger cells by zooplankton, and
growth rate related effects. Our data suggest a key role of zooplankton
fecal aggregates in carbon export for this part of the Southern Ocean (SO).
Additionally, in the southern part of the transect south of the Polar Front
(PF), the release of sea-ice algae during the ice demise in the Seasonal Ice
Zone (SIZ) is hypothesized to influence the isotopic signature of sterols in
the open ocean. Overall, the combined use of δ13C values and
concentrations measurements of both bulk organic C and specific sterols
throughout the water column offers the promising potential to explore the
recent history of plankton and the fate of organic matter in the SO. |
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