Airborne radionuclides and heavy metals in High Arctic terrestrial environment as the indicators of sources and transfers of contamination

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 revealed high spatial concentration variability of the analysed samples. Lithogenic radionuclides (230Th, 232Th, 234U, 238U) show less variability than the airborne radionuclides because their activity concentrations are controlled only by mixing of weathered material derived from different bedrock. Activity ratios of the artificial radionuclides differ in most cryoconite samples from global fallout signatures. The contribution of radionuclides from other sources might be enhanced by non-continuous exposure of cryoconite to atmospheric deposition. We assumed that the main source of Pu, which is visible only in cryoconite samples, are derived from nuclear tests and non-exploded weapons-grade material. Approximately one third of the total observed Pu activity concentration is 238Pu originating from a SNAP9A satellite re-entry and subsequent injection of nuclear debris from stratosphere into troposphere. In samples from Waldemarbreen we observed the effect of glacial morphology on effective trapping and storing of airborne radionuclides. The differences in the concentrations of radionuclides between sampling points and differences in the elevation gradient from terminus towards icefall may reflect the homogenous topography of the glacier tongue. The trace metal concentrations in soils were typical or slightly higher than concentrations characteristic for natural background concentrations and the 206Pb/207Pb ratio also was close to the natural ratio for parent rocks. Conversely, trace metal concentrations in cryoconite samples (Pb and Cd) were higher than in soil samples and definitely exceeded natural values.

90Sr level and behaviour in the terrestrial environment of Spitsbergen

“…The previous investigation for the Arctic archipelago of Svalbard concluded that the terrestrial environment was primarily contaminated with bomb-derived Pu isotopes and 137 Cs, and, to a lesser extent, by 137 Cs originating from the Chernobyl accident in 1986 [15]. For initial soils and cryoconite unexplained deviations from the weapons testing were noted, but mainly for 238 Pu/ 239+240 Pu and 240 Pu/ 239 Pu activity and mass ratios, respectively [29,31,33].…”

“…The cryoconite was collected from each sampling site, whereas the soil and peat profiles were derived only from the Werenskiold area. The details of scientific expeditions into the Werenskiold, Kafføyra and Kongsfjord areas and the description of the fieldworks were presented elsewhere [28,29,32,33,43]. Samples taken from the other study areas (i.e., Calypsobyen and Sørkapp Land), as a part of a wider scientific project, will be characterised in a future paper.…”