Wildfires to create second wave of radiation poisoning from Chernobyl
“A large amount of Caesium-137 still remains in the Chernobyl forests, which could be remobilized along with a large number of other dangerous, long-lived, refractory radionuclides. We predict that an expanding flammable area associated with climate change will lead to a high risk of radioactive contamination with characteristic fire peaks in the future,” said the abstract of a study published in Ecological Monographs magazine by the respected Norwegian Institute for Air Research.
The US Environmental Protection Agency describes Caesium-137 as a “highly radioactive” material that “increases the risk of cancer” and can cause death through severe exposure.
Of the 85 petabecquerels (a measure of radioactivity) released following the accident at the plant, between two and eight still remain in the soil.
The Norwegian team studied satellite images of the patterns of large-scale fires that originated in the 4800 sq. km exclusion zone – located on either side of Ukraine’s border with Belarus – in 2002, 2008, and 2010. The impacts of those fires, which spewed nearly a tenth as much radiation as the original fallout, were detected as far away as Scandinavia, Turkey, and Italy.
The scientists then used projections from the UN’s Intergovernmental Panel on Climate Change – which says the area will become even drier and more prone to fires – to make future predictions of even more severe radiation clouds spreading across the continent.
Furthermore, the scientists found that organic debris in the forest – key fuel for any potential fire – has been building up at twice the rate since 1986, as dead leaves in the area appear to decay at half the pace, due to radiation inhibiting natural biological processes.
The situation is made worse by the surprisingly slow decay of Caesium-137 itself. In lab conditions, its half-life is 30 years, meaning that by next year, it should be half as potent as at the time of the contamination. But in the dense vegetation that has sprung up in the exclusion zone, the element is cycled continuously between the soil and the leaves of the trees above.
The study, which notes that “current fire-fighting infrastructure in the region is inadequate due to understaffing and lack of funding,” predicts that the most potent combination of Caesium concentrations and wildfires will strike between 2023 and 2036, and realistic dangers will remain until 2060.
And what are the dangers of being exposed to these elements for humans?
The study estimates that during a wildfire fallout, an inhabitant of Kiev – located less than 100 km from Chernobyl – would be exposed to an average of 10 microsieverts of radiation, a relatively trivial dose which constitutes one percent of the prescribed annual radiation limit.
Unfortunately, the radiation is spread very unevenly in any cloud, and tends to concentrate in certain foods like mushrooms – meaning many are likely to receive a much higher, potentially life-changing exposure.
“The internal dose from ingestion can be significant. A growing body of information supports the idea that there is no threshold below which they have no effect,” Tim Mousseau of the University of South Carolina at Columbia, one of the co-authors of the study, told New Scientist.
A particular problem will be screening those who have been disproportionately affected, with the poisonings unnoticeable in the general population but “very significant for those who experience them."
The impact of the problem may stretch beyond Europe, also to Japan's Fukushima Daiichi Nuclear Power Plant, which released about a fifth to a quarter of Chernobyl’s Caesium-137 fallout during the nuclear meltdown in 2011.
"This is clearly an important problem and one that applies also to Fukushima, where a significant amount of forest land has been contaminated. The scientists have a very valid point. The lack of management of forests, the apparently slower decay of vegetation exposed to radiation, climate change leading to drought and the expansion of forested areas all contribute to increasing the risk of forest fire and therefore further dispersal of long-lived radioactive nuclides," said Keith Baverstock of the University of Eastern Finland in Kuopio.