Abstract
Abstract. Cryoconite is rich in natural and artificial radioactivity, but a discussion about its ability to accumulate radionuclides is lacking. A characterization of cryoconite from two Alpine glaciers is presented here. Results confirm that cryoconite is significantly more radioactive than the matrices usually adopted for the environmental monitoring of radioactivity, such as lichens and mosses, with activity concentrations exceeding 10 000 Bq kg−1 for single radionuclides. This makes cryoconite an ideal matrix to investigate the deposition and occurrence of radioactive species in glacial environments. In addition, cryoconite can be used to track environmental radioactivity sources. We have exploited atomic and activity ratios of artificial radionuclides to identify the sources of the anthropogenic radioactivity accumulated in our samples. The signature of cryoconite from different Alpine glaciers is compatible with the stratospheric global fallout and Chernobyl accident products. Differences are found when considering other geographic contexts. A comparison with data from literature shows that Alpine cryoconite is strongly influenced by the Chernobyl fallout, while cryoconite from other regions is more impacted by events such as nuclear test explosions and satellite reentries. To explain the accumulation of radionuclides in cryoconite, the glacial environment as a whole must be considered, and particularly the interaction between ice, meltwater, cryoconite and atmospheric deposition. We hypothesize that the impurities originally preserved into ice and mobilized with meltwater during summer, including radionuclides, are accumulated in cryoconite because of their affinity for organic matter, which is abundant in cryoconite. In relation to these processes, we have explored the possibility of exploiting radioactivity to date cryoconite.
Highlights
Radioecological research is primarily focused on the Earth surface, where continuous atmospheric deposition of fallout radionuclides (FRNs), both natural and artificial, is accumulated
The nuclides diagnostic for the separation in PC2 are the anthropogenic ones, which define the negative scores of Morteratsch samples, and unsupported 210Pb, which is linked to the positive scores of Forni cryoconite
We have described the ability of cryoconite to accumulate both artificial and natural FRNs
Summary
Radioecological research is primarily focused on the Earth surface, where continuous atmospheric deposition of fallout radionuclides (FRNs), both natural and artificial, is accumulated. Among the matrices used in the study of FRNs, those that receive the greatest attention share common features: their composition is directly influenced by airborne deposited impurities; the contribution from environmental compartments other than atmosphere is limited; they are widespread, accessible and preferably easy to sample. Given these attributes, lichens, mosses and peat are commonly used to study the distribution of FRNs and establish depositional inventories (Nifontova, 1995; Kirchner and Daillant, 2002)
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