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| Titel |
Oxygen and carbon isotope composition of modern planktic foraminifera and near-surface waters in the Fram Strait (Arctic Ocean) – a case study |
| VerfasserIn |
T. Pados, R. F. Spielhagen, D. Bauch, H. Meyer, M. Segl |
| 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 ; 12, no. 6 ; Nr. 12, no. 6 (2015-03-17), S.1733-1752 |
| Datensatznummer |
250117865
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| Publikation (Nr.) |
 copernicus.org/bg-12-1733-2015.pdf |
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| Zusammenfassung |
| The upper 500 m of the water column and the sediment surface along an E–W
transect in the Fram Strait were sampled for recent planktic foraminifera.
The δ18O and δ13C values of the tests are compared to the
stable isotope composition of the water samples taken from the same depths,
and related to the characteristics of the water column. The polar species
Neogloboquadrina pachyderma clearly dominates the species assemblage
in the Fram Strait in the early summer, while the subpolar
Turborotalita quinqueloba accounts only for 5–23%. In this
area the average depth of calcification of N. pachyderma lies
between 70–150 m water depth, T. quinqueloba shows a similar range
with 50–120 m water depth. The δ18O values of N. pachyderma show an average vital effect of about −1.5‰ compared
to calculated equilibrium calcite values. Except for the upper ∼75 m, the vertical profiles of δ13C of the net-sampled shells
are nearly parallel to the values measured in the water column with an
average offset of −1.6‰ and −3.6‰ for N. pachyderma and T. quinqueloba, respectively. The discrepancy found
in the upper ~75 m might indicate an influence of the "carbonate
ion effect" on the carbon isotope incorporation in the tests. Oxygen and
carbon isotopes from the sediment surface yield higher values than those from
the water column for both species. This may be because specimens from the
water column reflect a modern snapshot only, while tests from surface
sediments record environmental parameters from the past ~1000 years. |
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