EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Detection of an unknown emission source in the Baltic Sea using the new oceanographic tracer U-233/U-236

Karin Hain1, Ala Aldahan2, Mats Eriksson3,4, Robin Golser1, Gideon M. Henderson5, Xiaolin Hou6, Jixin Qiao6, Göran Possnert7, Peter Steier1, Vesa-Pekka Vartti8, and Haitao Zhang6,9
Karin Hain et al.
  • 1Faculty of Physics, University of Vienna, Vienna, Austria
  • 2Department of Geology, United Arab Emirates University, Al Ain, United Arab Emirates
  • 3Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
  • 4Department of Radiation Protection, Swedish Radiation Safety Authority, Stockholm, Sweden
  • 5Department of Earth Sciences, University of Oxford, Oxford, United Kingdom
  • 6Department of Environmental Engineering, Technical University of Denmark, Roskilde, Denmark
  • 7Tandem Laboratory, Uppsala University, Uppsala, Sweden
  • 8Environmental Radiation Surveillance, Radiation and Nuclear Safety Authority, Helsinki, Finland
  • 9Northwest Institute of Nuclear Technology, Xi’an, China

By analysing the two long-lived anthropogenic Uranium (U) isotopes U-233 and U-236 in different compartments of the environment affected by releases of nuclear power production or by global fallout from nuclear weapons tests, we showed that the corresponding isotopic ratios U-233/U-236 differ by one order of magnitude. Based on these experimental results which were obtained with the ultra-sensitive detection method Accelerator Mass Spectrometry, we suggested a representative ratio for nuclear weapons fallout of U-233/U-236 = (1.40 ± 0.15) ·10-2 and (0.12 ± 0.01) ·10-2 for releases from nuclear power production. Consequently, the U-233/U-236 ratio not only has the potential to become a novel sensitive fingerprint for releases from nuclear industry, but could also serve as a powerful oceanographic tracer due to the conservative behaviour of U in ocean water which does not suffer from chemical fractionation.

As a first application of this paired tracer, we studied the distribution of U-233 and U-236 concentrations in addition to I-129 in the Baltic Sea which is known to have received inputs of radionuclides from various contamination sources including the two European reprocessing plants, global fallout from weapons testings and fallout from the Chernobyl accident. Our data indicate an additional unidentified source of reactor U-236 in the Baltic Sea demonstrating the high sensitivity of the U-233/U-236 ratio to distinguish different emission sources in water mixing processes.

How to cite: Hain, K., Aldahan, A., Eriksson, M., Golser, R., Henderson, G. M., Hou, X., Qiao, J., Possnert, G., Steier, P., Vartti, V.-P., and Zhang, H.: Detection of an unknown emission source in the Baltic Sea using the new oceanographic tracer U-233/U-236, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14111,, 2021.

Corresponding displays formerly uploaded have been withdrawn.