EGU2020-8697
https://doi.org/10.5194/egusphere-egu2020-8697
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The long-lived anthropogenic radionuclides I-129 and U-236 as tracers of water mass provenance, circulation timescales and mixing in the Arctic Ocean and Fram Strait

Anne-Marie Wefing1,2, Núria Casacuberta1,2, Marcus Christl1, John N. Smith3, Paul A. Dodd4, Elena Chamizo5, Mercedes López-Lora5, and Hans-Arno Synal1
Anne-Marie Wefing et al.
  • 1Laboratory of Ion Beam Physics, ETH Zürich, Zürich, Switzerland (awefing@phys.ethz.ch)
  • 2Environmental Physics, ETH Zürich, Zürich, Switzerland
  • 3Bedford Institute of Oceanography, Fisheries and Oceans Canada, Dartmouth, NS, Canada
  • 4Norwegian Polar Institute, Tromso, Norway
  • 5Centro Nacional de Aceleradores, Sevilla Spain

Anthropogenic chemical tracers are powerful tools to study ocean circulation timescales, water mass provenance and mixing regimes. In the Arctic Ocean, the releases of artificial radionuclides from European nuclear reprocessing plants (RPs) act as valuable transient tracers as they label the inflowing Atlantic Waters with a distinct anthropogenic signal. In recent years, the combination of the two long-lived radionuclides 129I and 236U has emerged as a new tracer pair and several studies have shown their potential to track pathways and timescales of Atlantic Water circulation in the Arctic Ocean and Fram Strait.

The circulation times of Atlantic-origin waters in the Arctic Ocean that were inferred using this tracer pair (in combination with the naturally occurring 238U) agree to those obtained by means of other transient tracers. Moreover, the combination of 129I and 236U promises to be a useful marker of water mass mixing regimes both in the surface waters and the subsurface Atlantic layer. In particular, the interface between Atlantic and Pacific Waters in the polar surface layer of the Arctic Ocean can be easily identified as these two water masses are labelled by very different 129I/236U and 236U/238U atom ratios.

Here we present a compilation of 129I and 236U in a quasi-synoptic pan-arctic section including the Fram Strait and we show how this data can be used to gain information about circulation patterns. We discuss timescales and transport characteristics of Atlantic Water flow, the position and variability of the front between Atlantic and Pacific Waters and the temporal variability of Pacific Waters in the Fram Strait.

How to cite: Wefing, A.-M., Casacuberta, N., Christl, M., Smith, J. N., Dodd, P. A., Chamizo, E., López-Lora, M., and Synal, H.-A.: The long-lived anthropogenic radionuclides I-129 and U-236 as tracers of water mass provenance, circulation timescales and mixing in the Arctic Ocean and Fram Strait, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8697, https://doi.org/10.5194/egusphere-egu2020-8697, 2020

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