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Radiocarbon Reservoir Ages from Freshwater Lakes, South Georgia, Sub-Antarctic: Modern Analogues from Particulate Organic Matter and Surface Sediments

Published online by Cambridge University Press:  18 July 2016

Steven G Moreton ,
Gunhild C Rosqvist ,
Sarah J Davies  and
Michael J Bentley
Steven G Moreton
Affiliation:
NERC Radiocarbon Laboratory, Scottish Enterprise Technology Park, East Kilbride, G75 0QF, United Kingdom. Corresponding author. Email: S.Moreton@nercrcl.gla.ac.uk
Gunhild C Rosqvist
Affiliation:
Department of Physical Geography, Stockholm University, S-106 91 Stockholm, Sweden
Sarah J Davies
Affiliation:
Institute of Geography and Earth Sciences, University of Wales Aberystwyth, Llandinam Building, Aberystwyth, SY23 3DB, United Kingdom
Michael J Bentley
Affiliation:
Department of Geography, University of Durham, Science Site, South Road, Durham, DH1 3LE, United Kingdom
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Abstract

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Lake sediments have the potential to preserve proxy records of past climate change. Organic material suitable for radiocarbon dating often provides age control of such proxy records. Six shallow freshwater lakes on the sub-Antarctic island of South Georgia were investigated for carbon reservoir effects that may influence age-depth profiles from lake sediment records in this important region. Paired samples of particulate organic matter (POM) from the water column and surface sediment (bulk organic carbon) were analyzed by accelerator mass spectrometry 14C. POM in 4 lakes was found to be in equilibrium with the atmosphere (~107% modern), whereas 2 lakes showed significant depletion of 14C. In each lake, the surface sediment ages were older than the paired POM age. Surface sediment ages showed a much greater range of ages compared to the equivalent POM ages, even for lakes located in close proximity. We conclude that sediment disturbance during coring, bioturbation, and periodic resuspension of sediments are likely factors causing the difference in the apparent age of surface sediments.

Type
Part II
Information
Radiocarbon , Volume 46 , Issue 2: Proceedings of the 18th International Radiocarbon Conference (Part 2 of 2), Conference Editors: Nancy Beavan Athfield, Rodger J Sparks , 2004 , pp. 621 - 626
Copyright
Copyright © The Arizona Board of Regents on behalf of the University of Arizona 

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