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Bomb 14C in the Indian Ocean Measured by Accelerator Mass Spectrometry: Oceanographic Implications

Published online by Cambridge University Press:  18 July 2016

Edouard Bard
Affiliation:
Centre des Faibles Radioactivités (CFR), Laboratoire Mixte CNRS-CEA Pare du CNRS BP 1, F-91190, Gif-sur-Yvette, France Lamont-Doherty Geological Observatory (L-DGO), Columbia University, Palisades, New York 10964
Maurice Arnold
Affiliation:
Centre des Faibles Radioactivités (CFR), Laboratoire Mixte CNRS-CEA Pare du CNRS BP 1, F-91190, Gif-sur-Yvette, France
J R Toggweiler
Affiliation:
Geophysical Fluid Dynamics Laboratory (GFDL), Princeton University, Princeton, New Jersey 08540
Pierre Maurice
Affiliation:
Centre des Faibles Radioactivités (CFR), Laboratoire Mixte CNRS-CEA Pare du CNRS BP 1, F-91190, Gif-sur-Yvette, France
Jean-Claude Duplessy
Affiliation:
Centre des Faibles Radioactivités (CFR), Laboratoire Mixte CNRS-CEA Pare du CNRS BP 1, F-91190, Gif-sur-Yvette, France
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Abstract

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AMS 14C measurements on samples collected in the tropical-equatorial Indian Ocean during the INDIGO program (leg II, 1986) are presented and compared with β-counting results obtained under both INDIGO program and GEOSECS expedition in the Indian Ocean (1978). The most significant observation is a doubling of the bomb-14C inventory and mean penetration depth in the equatorial zone. Based on hydrologic considerations, two hypotheses can be proposed: 1) direct influx of Pacific mid-latitude waters through the Indonesian archipelago and 2) advection and/or mixing with Mode Water from the southern gyre of the Indian Ocean. Results obtained with a general circulation model of the ocean suggest that the influx from the Pacific is important in the upper 300m and that below 500m the bomb-14C budget is dominated by Mode Water advection.

Type
II. Carbon Cycle in the Environment
Copyright
Copyright © The American Journal of Science 

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