Oxygen and carbon isotope composition of modern planktic foraminifera and near-surface waters in the Fram Strait (Arctic Ocean) – a case-study.

Pados, Theodora, Spielhagen, Robert F., Bauch, Dorothea , Meyer, H. and Segl, M. (2015) Oxygen and carbon isotope composition of modern planktic foraminifera and near-surface waters in the Fram Strait (Arctic Ocean) – a case-study. Open Access Biogeosciences (BG), 12 (6). pp. 1733-1752. DOI 10.5194/bg-12-1733-2015.

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Abstract

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 water samples taken from the same depths, and related to the characteristics of the water column. The polar species Neogloboquadrina pachyderma (sin.) 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 (sin.) lies between 70–150m water depth, T. quinqueloba shows a similar range with 50–120 m water depth. The δ18O values of N. pachyderma (sin.) 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 (sin.) and T. quinqueloba, respectively. The discrepancy found in the upper ~ 75 m might indicate the 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.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/238111
Additional Information: WOS:000352112900008
Keywords: Planktic foraminifera; Fram Strait, Arctic Ocean
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
AWI
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/bg-12-1733-2015
ISSN: 1726-4170
Projects: Marie-Curie Actions, Laptev Sea System, Transdrift
Expeditions/Models/Experiments:
Date Deposited: 16 Jun 2014 10:17
Last Modified: 19 Dec 2017 12:44
URI: http://oceanrep.geomar.de/id/eprint/24746

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