“These materials are a product of what we have put into the atmosphere. This is just showing that our nuclear legacy hasn’t disappeared yet. It’s still there,” said Caroline Clason, a lecturer in Physical Geography at the University of Plymouth of a study published in Nature that surveyed 19,000 of Earth’s glaciers and found their total melt amounts to a loss of 335 billion tons of ice each year, more than measurements of previous studies.
“When it was built in the early 1900s, the road into Mount Rainier National Park from the west passed near the foot of the Nisqually Glacier, one of the mountain’s longest,” reports the New York Times. “Visitors could stop for ice cream at a stand built among the glacial boulders and gaze in awe at the ice. The ice cream stand (image below) is long gone.”
The glacier now ends more than a mile farther up the mountain, and they are melting elsewhere around the world too.
This scary scenario of our nuclear legacy was explored by an international team of scientists who studied the spread of radioactive contaminants in Arctic glaciers throughout Sweden, Iceland, Greenland, the Norwegian archipelago Svalbard, the European Alps, the Caucasus, British Columbia, and Antarctica. The researchers shared their results at the 2019 General Assembly of the European Geosciences Union (EGU) in Vienna.
It found man made radioactive material at all 17 survey sites, often at concentrations at least 10 times higher than levels elsewhere. “They are some of the highest levels you see in the environment outside nuclear exclusion zones,” said Clason.
Fallout radionuclides (FRNs) were detected these sites. Radioactive material was found embedded within ice surface sediments called “cryoconite,” and at concentration levels ten times greater than the surrounding environment.“ They are some of the highest levels you see in the environment outside nuclear exclusion zones,” Clason, who led the research project, told AFP.
The Chernobyl disaster of 1986—by far the most devastating nuclear accident to date—released vast clouds of radioactive material including Caesium into the atmosphere, causing widespread contamination and acid rain across northern Europe for weeks afterwards. “Radioactive particles are very light so when they are taken up into the atmosphere they can be transported a very long way,” she told AFP. “When it falls as rain, like after Chernobyl, it washes away and it’s sort of a one-off event. But as snow, it stays in the ice for decades and as it melts in response to the climate it’s then washed downstream.”
The environmental impact of this has been shown in recent years, as wild boar meat in Sweden was found to contain more than 10 times the safe levels of Caesium.
“We’re talking about weapons testing from the 1950s and 1960s onwards, going right back in the development of the bomb,” Clason said. “If we take a sediment core you can see a clear spike where Chernobyl was, but you can also see quite a defined spike in around 1963 when there was a period of quite heavy weapons testing.”
Weapons tests can fling radioactive detritus up to 50 miles in the air. Smaller, lighter materials will travel into the upper atmosphere, and may “circulate around the world for years, or even decades, until they gradually settle out or are brought back to the surface by precipitation,” according to the Environmental Protection Agency.
Fallout is comprised of radionuclides such as Americium-241, Cesium-137, Iodine-131, and Strontium-90. Depending on a material’s half-life, it could remain in the environment minutes to years before decaying. Their levels of radiation also vary.
Particles can return to the immediate area as acid rain that’s absorbed by plants and soil, wreaking havoc on ecosystems, human health, and communities. But radionuclides that travel far and wide can settle in concentrated levels on snow and ice—large amounts of radioactive material from Fukushima was found in 2011 on four glaciers in the Tibetan Plateau, for example.
One of the most potentially hazardous residues of human nuclear activity is Americium, which is produced when Plutonium decays. Whereas Plutonium has a half-life of 14 years, Americium lasts 400.
“Americium is more soluble in the environment and it is a stronger alpha (radiation) emitter. Both of those things are bad in terms of uptake into the food chain,” said Clason. While there is little data available on how these materials can be passed down the food chain—even potentially to humans—Clason said there was no doubt that Americium is “particularly dangerous”.
As geologists look for markers of the epoch when mankind directly impacted the health of the planet—known as the Anthropocene—Clason and her team believe that radioactive particles in ice, soil and sediment could be an important indicator.
The team hopes that future research will investigate how fallout could disperse into the food chain from glaciers, calling it a potential “secondary source of environmental contamination many years after the nuclear event of their origin.”