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On the 14C and 39Ar Distribution in the Central Arctic Ocean: Implications for Deep Water Formation1

Published online by Cambridge University Press:  18 July 2016

Peter Schlosser ,
Bernd Kromer ,
Gote Östlund ,
Brenda Ekwurzel ,
Gerhard Bönisch ,
H. H. Loosli  and
Roland Purtschert
Peter Schlosser
Affiliation:
Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964 USA Department of Geological Sciences of Columbia University, Palisades, New York 10964 USA
Bernd Kromer
Affiliation:
Institut für Umweltphysik der Universität Heidelberg, Im Neuenheimer Feld 366, D-69120 Heidelberg, Germany
Gote Östlund
Affiliation:
Rosenstiel School of Marine and Atmospheric Science, University of Miami, Rickenbacker Causeway, Miami, Florida 33149 USA
Brenda Ekwurzel
Affiliation:
Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964 USA Department of Geological Sciences of Columbia University, Palisades, New York 10964 USA
Gerhard Bönisch
Affiliation:
Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964 USA
H. H. Loosli
Affiliation:
Physikalisches Institut der Universität Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
Roland Purtschert
Affiliation:
Physikalisches Institut der Universität Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
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We present ΔA14C and 39Ar data collected in the Nansen, Amundsen and Makarov basins during two expeditions to the central Arctic Ocean (RV Polarstern cruises ARK IV/3, 1987 and ARK VIII/3, 1991). The data are used, together with published Δ14C values, to describe the distribution of Δ14C in all major basins of the Arctic Ocean (Nansen, Amundsen, Makarov and Canada Basins), as well as the 39Ar distribution in the Nansen Basin and the deep waters of the Amundsen and Makarov Basins. From the combined Δ14C and 39Ar distributions, we derive information on the mean “isolation ages” of the deep and bottom waters of the Arctic Ocean. The data point toward mean ages of the bottom waters in the Eurasian Basin (Nansen and Amundsen Basins) of ca. 250-300 yr. The deep waters of the Amundsen Basin show slightly higher 3H concentrations than those in the Nansen Basin, indicating the addition of a higher fraction of water that has been at the sea surface during the past few decades. Correction for the bomb 14C added to the deep waters along with bomb 3H yields isolation ages for the bulk of the deep and bottom waters of the Amundsen Basin similar to those estimated for the Nansen Basin. This finding agrees well with the 39Ar data. Deep and bottom waters in the Canadian Basin (Makarov and Canada Basins) are very homogeneous, with an isolation age of ca. 450 yr. Δ14C and 39Ar data and a simple inverse model treating the Canadian Basin Deep Water (CBDW) as one well-mixed reservoir renewed by a mixture of Atlantic Water (29%), Eurasian Basin Deep Water (69%) and brine-enriched shelf water (2%) yield a mean residence time of CBDW of ca. 300 yr.

Type
Articles
Information
Radiocarbon , Volume 36 , Issue 3 , 1994 , pp. 327 - 343
Copyright
Copyright © The American Journal of Science 

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