The icy surfaces of glaciers are punctured with cryoconites – small, cylindrical holes filled with meltwater, with thin films of mineral and organic dust, microorganisms, and other particles at the bottom of the hole.
New research conducted by Polish scientists reveals that cryoconites also contain a thin film of extremely radioactive material.
The study confirms previous findings of high levels of radioactivity in the Arctic and warns that as Arctic glaciers rapidly melt, the radioactivity stored in them will be released into downstream water sources and ecosystems.
The study, headed by Edyta Łokas of the Institute of Nuclear Physics at the Polish Academy of Sciences and researchers from three other Polish universities, was published in Science Direct in June.
The study examines Hans Glacier in Spitsbergen, the largest and only permanently populated island of the glacier-covered Svalbard archipelago, off the northern Norwegian coast in the Arctic Ocean. While investigating the radionuclide and heavy metal contents of glacial cryoconites, the researchers revealed that the dust retains heavy amounts of airborne radioactive material and heavy metals on glacial surfaces.
This radioactive material comes from both natural and anthropogenic, or human-caused, sources, according to the study. However, the researchers determined through isotope testing that this deposition was mainly linked to human activity.
Head researcher Edyta Lokas says she believes that this radioactive material mainly derives from nuclear weapons usage and testing.
“The radionuclide ratio signatures point to the global fallout [from nuclear weapon testing], as the main source of radioactive contamination on Svalbard. However, some regional contribution, probably from the Soviet tests performed on Novaya Zemlya was also found,” Lokas wrote in an email to GlacierHub.
The Arctic region bears an unfortunate history of radioactive contamination, from an atom bomb going missing at the U.S. base in Thule, Greenland, to radiation from Chernobyl getting picked up by lichens in Scandinavia, making reindeer milk dangerous.
But how does all this radioactive materials end up in the Arctic?
The Arctic, and polar regions in general, often become contaminated through long-range global transport.
In this process, airborne radioactive particles travel through the atmosphere before eventually settling down on a ground surface. While these particles can accumulate in very small, non harmful amounts in soils, vegetation, and animals in all areas of the world, geochemical and atmospheric processes carry the majority of radioactive particles to the Poles.
Once the particles reach the Poles, “sticky” organic substances excreted by microorganisms living in cryoconites attract and accumulate high levels of radioactivity and other toxic metals.
As cryoconites occupy small, but deep holes, on glacier surfaces, they are often left untouched for decades, Edyta explains. Cryoconites also accumulate radioactive substances that are transported with meltwater flowing down the glacier during summertime.
Climate change lends extra meaning to the study, as the researchers note that, “the number of additional contamination sources may rise in future due to global climate changes.”
They expect that both air temperature increases and changes to atmospheric circulation patterns and precipitation intensity will all quicken the pace of contamination transport and extraction from the atmosphere.
Edtya explained that as Arctic glaciers retreat, “The radioactivity contained in the cryoconites is released from shrinking glaciers and incorporated into the Arctic ecosystem.” She said she hopes that future climate change vulnerability assessments of the Arctic to pollution consider cryoconite radioactivity.