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The Marine Radiocarbon Bomb Pulse Across the Temperate North Atlantic: A Compilation of Δ14C Time Histories from Arctica Islandica Growth Increments

Published online by Cambridge University Press:  18 July 2016

James D Scourse ,
Alan D Wanamaker Jr ,
Chris Weidman ,
Jan Heinemeier ,
Paula J Reimer ,
Paul G Butler ,
Rob Witbaard  and
Christopher A Richardson
James D Scourse*
Affiliation:
School of Ocean Sciences, College of Natural Sciences, Bangor University, Bangor LL59 5AB, United Kingdom
Alan D Wanamaker Jr
Affiliation:
Department of Geological and Atmospheric Sciences, 253 Science I, Iowa State University, Ames, Iowa 50011-3212, USA
Chris Weidman
Affiliation:
Waquoit Bay National Estuarine Research Reserve, PO Box 3092, 149 Waquoit Highway, Waquoit, Massachusetts 02536, USA
Jan Heinemeier
Affiliation:
AMS 14C Dating Centre, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
Paula J Reimer
Affiliation:
14CHRONO Centre, Queen's University Belfast, Belfast BT7 INN, Northern Ireland, United Kingdom
Paul G Butler
Affiliation:
School of Ocean Sciences, College of Natural Sciences, Bangor University, Bangor LL59 5AB, United Kingdom
Rob Witbaard
Affiliation:
Department of Marine Ecology, Royal Netherlands Institute for Sea Research (NIOZ), PO Box 59, 1790 AB Den Burg, Texel, the Netherlands
Christopher A Richardson
Affiliation:
School of Ocean Sciences, College of Natural Sciences, Bangor University, Bangor LL59 5AB, United Kingdom
*
Corresponding author. Email: j.scourse@bangor.ac.uk.
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Abstract

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Marine radiocarbon bomb-pulse time histories of annually resolved archives from temperate regions have been underexploited. We present here series of Δ14C excess from known-age annual increments of the long-lived bivalve mollusk Arctica islandica from 4 sites across the coastal North Atlantic (German Bight, North Sea; Troms⊘, north Norway; Siglufjordur, north Icelandic shelf; Grimsey, north Icelandic shelf) combined with published series from Georges Bank and Sable Bank (NW Atlantic) and the Oyster Ground (North Sea). The atmospheric bomb pulse is shown to be a step-function whose response in the marine environment is immediate but of smaller amplitude and which has a longer decay time as a result of the much larger marine carbon reservoir. Attenuation is determined by the regional hydrographic setting of the sites, vertical mixing, processes controlling the isotopic exchange of 14C at the air-sea boundary, 14C content of the freshwater flux, primary productivity, and the residence time of organic matter in the sediment mixed layer. The inventories form a sequence from high magnitude-early peak (German Bight) to low magnitude-late peak (Grimsey). All series show a rapid response to the increase in atmospheric Δ14C excess but a slow response to the subsequent decline resulting from the succession of rapid isotopic air-sea exchange followed by the more gradual isotopic equilibration in the mixed layer due to the variable marine carbon reservoir and incorporation of organic carbon from the sediment mixed layer. The data constitute calibration scries for the use of the bomb pulse as a high-resolution dating tool in the marine environment and as a tracer of coastal ocean water masses.

Type
Articles
Information
Radiocarbon , Volume 54 , Issue 2 , 2012 , pp. 165 - 186
Copyright
Copyright © 2012 by the Arizona Board of Regents on behalf of the University of Arizona 

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