Traces of nuclear weapons testing and accidents have been found in glaciers across the planet.
Fallout radionuclides had previously been found at glaciers relatively close to the sites of nuclear events, such as the Austrian alps after the Chernobyl disaster of 1986. But researchers have now discovered that these radionuclides are spread more widely, and can persist for decades after their release.
Caroline Clason of Plymouth University, UK, and her colleagues have detected radionuclides at 17 sites across the world, including Greenland, Antarctica, the Caucasus mountains between Europe and Russia, and British Columbia in Canada. They examined two man-made radioactive isotopes 鈥� Caesium, which was emitted in great quantities by the Chernobyl explosion, and Americium, which is produced by nuclear weapons testing.
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Once released, radionuclides travel through the atmosphere before coming down in snow upon glaciers. They are then absorbed by sediment on the top of glaciers known as cryonite. This is a mix of biological and mineral material that acts like a sponge, absorbing the isotopes.
The team found both radionuclides at every site they examined, with the smallest levels in Europe seen in Iceland, where volcanic ash is thought to impede the absorption of isotopes by cryonite.
Lichens and mosses growing near glaciers were found to have even higher concentrations of radionuclides.
Clason said the levels found in the glaciers are potentially harmful, but more work is needed to see if they pose a risk to humans and other animals. 鈥淲e don鈥檛 know to what extent this will be harmful to water quality and the food chain,鈥� she says.
The contaminated cryonite will certainly make its way downstream and into water systems, she adds, but there is then a question mark over how harmful the concentrations are when they are ingested by reindeer or other animals.
Clason presented the team鈥檚 work at the Earth Geoscience Union General Assembly in Vienna, Austria, last month.
