Radioecological and geochemical peculiarities of cryoconite on Novaya Zemlya glaciers

Abstract

In recent years, cryoconite has received growing attention from a radioecological point of view, since several studies have shown that this material is extremely efficient in accumulating natural and anthropogenic radionuclides. The Novaya Zemlya Archipelago (Russian Arctic) hosts the second largest glacial system in the Arctic. From 1957 to 1962, numerous atmospheric nuclear explosions were conducted at Novaya Zemlya, but to date, very little is known about the radioecology of its ice cap. Analysis of radionuclides and other chemical elements in cryoconite holes on Nalli Glacier reveals the presence of two main zones at different altitudes that present different radiological features. The first zone is 130–210 m above sea level (a.s.l.), has low radioactivity, high concentrations of lithophile elements and a chalcophile content close to that of upper continental crust clarkes. The second zone (220–370 m a.s.l.) is characterized by high activity levels of radionuclides and “inversion” of geochemical behaviour with lower concentrations of lithophiles and higher chalcophiles. In the upper part of this zone (350–370 m a.s.l.), 137Cs activity reaches the record levels for Arctic cryoconite (5700–8100 Bq/kg). High levels of Sn, Sb, Bi and Ag, significantly exceeding those of upper continental crust clarkes, also appear here. We suggest that a buried layer of contaminated ice that formed during atmospheric nuclear tests serves as a local secondary source of radionuclide contamination. Its melting is responsible for the formation of this zone.

137Cs and isotopic ratios of Pu and U in lichens and mosses from Russian Arctic areas

“…Cryoconites have been formed from fine-grained dark sediment accompanied with microbes, rocks, soot, algae, etc., which all have been carried by the wind even from far distances and deposited onto glacial surface or onto snow. Accumulation of radionuclides and other pollutants in the cryoconites have been studied, e.g., by Łokas et al ( 2016 , 2017 , 2018 , 2022 ), Owen et al ( 2019 ), and Miroshnikov et al ( 2021 ). Since the dark colour of cryoconites enhances melting of surrounding glacier or snow, release of accumulated radionuclides and other pollutants from the cryoconites into terrestrial environment can be substantial; this is a concern in the future assessments of climate change effects in the Arctic environments.…”

“…Since the dark colour of cryoconites enhances melting of surrounding glacier or snow, release of accumulated radionuclides and other pollutants from the cryoconites into terrestrial environment can be substantial; this is a concern in the future assessments of climate change effects in the Arctic environments. Miroshnikov et al ( 2021 ) determined the activity concentration of 137 Cs in cryoconites from Nalli Glacier, Novaya Zemlya, in 2018, and the range was from 244 ± 4 to 8093 ± 69 Bq/kg per dry mass where the mean value was 4049 ± 33 Bq/kg. The activity concentration range varies greatly in cryoconites, depending on the exact sampling site and various other factors, as the activity concentration of 137 Cs was observed to vary between 58 ± 2–2076 ± 20 Bq/kg (mean value 354 ± 4 Bq/kg) in the same sampling site in 2017 (Miroshnikov et al 2021 ).…”

“…Miroshnikov et al ( 2021 ) determined the activity concentration of 137 Cs in cryoconites from Nalli Glacier, Novaya Zemlya, in 2018, and the range was from 244 ± 4 to 8093 ± 69 Bq/kg per dry mass where the mean value was 4049 ± 33 Bq/kg. The activity concentration range varies greatly in cryoconites, depending on the exact sampling site and various other factors, as the activity concentration of 137 Cs was observed to vary between 58 ± 2–2076 ± 20 Bq/kg (mean value 354 ± 4 Bq/kg) in the same sampling site in 2017 (Miroshnikov et al 2021 ). Even higher activity concentrations of 137 Cs have been found in cryoconites in Norway, where the range was 12.9 ± 0.8–24.5 ± 12.3 kBq/kg and average value was 17.9 ± 3.6 kBq/kg in 2018 (Łokas et al 2022 ).…”

“…For example, an original article by Matishov et al ( 1994b ) including activity concentrations of radionuclides in soil, lichen, and moss samples from Barents Sea islands and Novaya Zemlya is no longer available, but fortunately, Szczypa and Reszka ( 1998 ) published their own dataset on the similar topic. A more recent study explored cryoconite samples from Nalli glacier, Novaya Zemlya (Miroshnikov et al 2021 ).…”