Nuclear fallout, fallout

By Andru McCracken


When the Rocky Mountain Goat reported on nuclear fallout collecting at the snout of a local glacier, American environmental activist

Joseph DeMare wanted to know the isotopes involved as well as the level of radiation.

“Those of us who follow the nuclear industry and radiation issues learned decades ago that the actual facts … are much more useful in assessing the seriousness of contamination than the opinions of ‘experts,’” he wrote.

UNBC researcher Philip Owens was pleased his research on fallout radionuclides was generating discussion.
To DeMare’s question, he said the fallout radionuclides investigated were caesium-137, americum-241 as well as a naturally occurring fallout product lead-210.

“Taking the caesium-137 values as an example, we measured activity concentrations in the glacial sediment from Castle Creek glacier of up to about 4000 Bq/kg,” said Owens.

That may not mean much, but at a project he’s undertaking in the Nechako River near Vanderhoof, the values are far lower – between 1 and 20 Bq/kg.

“So clearly the glacial sediments are highly elevated,” said Owens. “…one could go to most soils and measure some level of this radioactive fallout product, but they are very low levels. In addition, levels decrease to half their value every 30 years in the case of caseium-137 due to its radioactive half-life (i.e. about 30 years).”

Owens reiterated that above-ground atom bomb tests of the 50s and 60s released radioactive products into the stratosphere and the entire globe received fallout.

Concentrations around nuclear accidents like Chernobyl and Fukushima could be hundreds of times higher but even short- to medium-term exposure to levels at Castle Creek glacier could pose a health concern.

“The key message of the study is that with retreating glaciers and more glacial meltwater coming into contact with sediment on the surface of glaciers, that the sediment is acting as a sponge and absorbing contaminants that were previously locked up in the glacier,” Owens said.

“This sediment is also being released to downstream rivers, but at the moment is getting diluted with other, clean sediment, such that levels are not presently a concern for most aquatic ecosystems and human health,” he said. “But this situation could change and does require us to monitor the quality of the water and sediment coming from glaciers.”

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