Abstract
Abstract. A survey of airborne radioactive isotopes (137Cs, 238Pu, 239+240Pu, 241Am, and 210Pb) and trace metals (Pb, Cu, Zn, Cd, Fe, Al) in tundra soils and cryoconite hole material sampled from several locations in the Kaffiøyra region of Spitsbergen revealed significant variability in spatial concentration. Lithogenic radionuclides (230Th, 232Th, 234U, 238U) show less variability than the airborne radionuclides because their activity concentrations are controlled by mixing of local material derived from different types of bedrock. Activity ratios of the artificial radionuclides in most cryoconite samples differ from global fallout signatures. The contribution of radionuclides from additional and more specific sources might be enhanced by non-continuous exposure of cryoconite to atmospheric deposition. We assumed that the main source of Pu, which was detected only in cryoconite samples, is derived from nuclear tests and non-exploded weapons-grade material. Approximately one-third of the total observed Pu activity concentration is 238Pu, most likely originating from the SNAP9A satellite re-entry, which was powered by a 238Pu thermoelectric generator. In samples from Waldemarbreen the influence of glacial local morphology on the capability of cryoconite for trapping and accumulating airborne radionuclides is apparent. Local glacial morphology plays an important role in determining the accumulation of airborne pollutants. Trace metal concentrations in soils were typical or slightly higher than concentrations characteristic for the natural background; the 206Pb∕207Pb signature was also close to the natural ratio of the parent rocks. Conversely, trace metal concentrations in cryoconite samples (Pb and Cd) were higher than in soil samples and exceeded natural values. Cryoconite is an effective monitor of the spread of artificial radionuclides and heavy metals in their surrounding environment.
Highlights
The radioactive nuclides in the environment originate from both natural and anthropogenic sources
The main objective of this study is to evaluate the concentrations of artificial (137Cs, 238,239+240Pu, 241Am) and natural (210Pb, 230Th, 232Th, 234U, 238U) radionuclides and trace metals (Pb, Cu, Zn, Cd, Fe, Al) in cryoconite holes and tundra soils sampled in several locations in the Kaffiøyra region (Spitsbergen) and to identify and constrain the different sources of contamination based on the isotopic ratios of measured radionuclides and metals (238Pu/239+240Pu, 241Am/239+240Pu, 239+240Pu/137Cs, 240Pu/239Pu, 206Pb/207Pb, and 208Pb/206Pb)
Activity concentrations and inventories of anthropogenic radionuclides (137Cs, 238Pu, 239+240Pu, 241Am) for tundra soil profiles and for cryoconite are shown in Table S2 and Fig. 2 and in Table S4 and Fig. 2, respectively
Summary
The radioactive nuclides in the environment originate from both natural and anthropogenic sources. The primary sources of anthropogenic heavy metals include industry, mining, agriculture, fuel burning, waste disposal, and transportation (Pacyna and Pacyna, 2001). Artificial radionuclides and heavy metals are transported across the world mainly via the atmosphere, oceanic currents, and rivers. These materials can be found in remote Earth locations like the polar cryosphere. Elevated radionuclide and heavy metal levels have been reported in Asian and European glaciers (Barbante et al, 2004; Aizen et al, 2009; Eyrikh et al, 2017; Baccollo et al, 2017) and in remote Arctic and Antarctic areas (Hur et al, 2007; Singh et al, 2013)
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