EGU21-8795, updated on 09 Aug 2023
https://doi.org/10.5194/egusphere-egu21-8795
EGU General Assembly 2021
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Deposition  of plutonium isotopes in glacial environments in the Northern and Southern Hemispheres

Edyta Łokas1, Giovanni Baccolo Baccolo2, Caroline Clason3, Przemysław Wachniew4, Nozomu Takeuchi5, Krzysztof Zawierucha6, Dylan Beard7, Roberto Ambrosini8, Francesca Pittino9, Andrea Franzetti10, Phil Owens11, Ewa Poniecka12, William Blake13, Massimiliano Nastasi14, and Jakub Buda15
Edyta Łokas et al.
  • 1Institute of Nuclear Physics PAS, Department of Nuclear Physical Chemistry, Krakow, Poland (edyta.lokas@ifj.edu.pl)
  • 2University Milano-Bicocca, Milano, Italy
  • 3Earth and Environmental Sciences, University of Plymouth, Plymouth, United Kingdom
  • 4AGH University of Science and Technology, Krakow, Poland
  • 5Chiba University, Japan
  • 6Adam Mickiewicz University in Poznań, Poznań, Poland
  • 7Earth and Environmental Sciences, University of Plymouth, Plymouth, United Kingdom
  • 8University of Milan, Italy
  • 9University Milano-Bicocca, Milano, Italy
  • 10University of Milano-Bicocca, Italy
  • 11University of Northern British Columbia, Prince George, Canada
  • 12Cardiff University, Cardiff, United Kingdom
  • 13Earth and Environmental Sciences, University of Plymouth, Plymouth, United Kingdom
  • 14University Milano-Bicocca, Milano, Italy
  • 15Adam Mickiewicz University, Poznań, Poland

Glaciers are temporary repositories for radionuclides and other airborne contaminants (eg. heavy metals). Retreat of glaciers results in the release of these contaminants to downstream ecosystems where they can be accumulated by biota, with further consequences along the trophic chain. Fallout radionuclides, and especially Pu released from nuclear weapons testing and nuclear accidents, concentrates on glacier surfaces in cryoconite granules. These aggregates of mineral and organic components are associated with biological consortia composed of archaea, algae, cyanobacteria, fungi and heterotrophic bacteria (Cook et al., 2016). Cryoconite is also responsible for local decrease ice albedo and is responsible for formation of water-filled holes. Contaminants are effectively trapped in cryoconite granules for long periods (up to decades) due to the “sticky” nature of the material. Cryoconite can thus be useful in monitoring of radionuclide deposition on glaciers (Łokas et al., 2019; Giovanni et al., 2020).

Our collective research reveals widespread incidence of Pu isotopes in cryoconite across multiple sites on both hemispheres, including Svalbard, Sweden, Norway, Iceland, Greenland, British Columbia, Alaska, the European Alps, the Caucasus, Siberia, Tien Shan, Altai, South America and Antarctica. The levels of plutonium isotopes (238,239,240Pu) found in cryoconite at these sites are orders of magnitude higher than those detected in non-glaciated environments, raising important questions around the role of glaciers, and specifically cryoconite, in concentrating levels of Pu isotopes above those found in the surrounding environment. The activity ratios of 238Pu/239+240Pu show that the plutonium-related radioactivity of cryoconite from the Northern hemisphere is compatible with the worldwide signal from the global radioactive fallout (0.025) but in some samples from Svalbard higher activity ratios are associated with an additional source of pure 238Pu, pointing to an influence of the SNAP-9A satellite burn up in the atmosphere occurred in 1964. Also activity ratios from South America and Antarctica are consistent with the global radioactive fallout ratio (including SNAP 9 re-entry) in the southern hemisphere (0.14), with an exception concerning cryoconite from the Exploradores Glacier (Chilean Patagonia, ratio 0.35). There are no known nuclear test sites near this glacier which could explain this anomalous value. However, there is also no information about the atmospheric re-entry of the automatic Interplanetary Station “Mars’96” which was launched on 16 November 1996. It fell off the coast of Chile near the border with Bolivia and was not found so far. There were considerable quantities of 238Pu on board of the station, with a total activity of 174 TBq (IAEA, 2001). We hypothesize that this event could explain the anomaly observed at Exploradores Glacier, confirming the unmatched potential of cryoconite to study environmental radioactivity in glacial contexts.

Acknowledgements

This study was supported by the National Science Center grant no. NCN 2018/31/B/ST10/03057.

References

Cook et al., 2016. Progress in Physical Geography, 40(1), 66-111.

Giovanni et al., 2020. CATENA, 191, 104577.

IAEA, 2001. International Atomic Energy Agency IAEA, Vienna).

Łokas et al., 2019. The Cryosphere, 13(7), 2075-2086.

How to cite: Łokas, E., Baccolo, G. B., Clason, C., Wachniew, P., Takeuchi, N., Zawierucha, K., Beard, D., Ambrosini, R., Pittino, F., Franzetti, A., Owens, P., Poniecka, E., Blake, W., Nastasi, M., and Buda, J.: Deposition  of plutonium isotopes in glacial environments in the Northern and Southern Hemispheres, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8795, https://doi.org/10.5194/egusphere-egu21-8795, 2021.

Corresponding displays formerly uploaded have been withdrawn.