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AGU: Paleoceanography

 

Keywords

  • alkenones
  • proxy calibration
  • Nordic seas
  • plankton
  • coccolithophore

Index Terms

  • Biogeosciences: Biosignatures and proxies
  • Biogeosciences: Paleoclimatology and paleoceanography
  • Biogeosciences: Biomolecular and chemical tracers
  • Geochemistry: Organic and biogenic geochemistry
Abstract
Cited By (4)
 

Abstract

Variability of unusual distributions of alkenones in the surface waters of the Nordic seas

James Bendle

Environmental Research Centre, Department of Geography, University of Durham, Durham, UK

Antoni Rosell-Melé

Catalan Institute for Research and Advanced Studies, Institut de Ciència i Tecnologia Ambientals, Universitat Autònona de Barcelona, Bellaterra, Catalonia, Spain

Patrizia Ziveri

Faculty of Earth and Life Sciences, Department of Paleoecology and Paleoclimatology, Vrije Universiteit, Amsterdam, Netherlands

Samples of filtered particulate organic matter (POM) were obtained during the summers of 1999 and 2000 from the surface waters of the Nordic seas to monitor the spatial distribution of long-chain alkenones. The aim of the study was to appraise existing alkenone-based climatic proxies in northern high latitudes. Unusually high percentages of the tetraunsaturated alkenone were measured in the polar waters of the East Greenland Current, with C37:4 of up to 77% in 80% of sea-ice cover. Values of percent C37:4 across the Nordic seas showed a strong association with water mass type. Analysis of coccoliths in filters indicated that calcified Emiliania huxleyi could not be discounted as the biological precursor of alkenones in all the water masses. A combined data set of 69 samples of POM revealed a stronger correlation of percent C37:4 to sea surface salinity (SSS; R2 = 0.72) than to sea surface temperature (SST; R2 = 0.50). Values of percent C37:4 in sea surface POM were much higher than those in surficial sediments of the northern North Atlantic. To explain the discrepancy in sedimentary and surface water column percent C37:4, we propose that the alkenone contents in surface sediments underlying arctic and polar waters are a combination of autochthonous and allochthonous inputs of alkenones. Our results show that percent C37:4 can be used to reconstruct the relative extension of arctic/polar water masses in the North Atlantic. However, the results prevent confirmation of percent C37:4 as a paleo-SSS proxy in the Nordic seas, given its multivariate nature in our data set and the decoupling between its range of values in surface waters and sediments.

Received 5 March 2004; accepted 23 November 2004; published 6 April 2005.

Citation: Bendle, J., A. Rosell-Melé, and P. Ziveri (2005), Variability of unusual distributions of alkenones in the surface waters of the Nordic seas, Paleoceanography, 20, PA2001, doi:10.1029/2004PA001025.

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