Researchers at the University of Waterloo and Nipissing University have released some of the first ever calculations about the amount of arsenic stored in areas at high risk of wildfires around Yellowknife, where metal mining and smelting have been commonplace for decades.
The research shows that during the 2023 wildfire season — the most destructive ever recorded in Canada — four wildfires in mine-impacted areas around Yellowknife and the Northwest Territories potentially contributed up to half of the arsenic that wildfires typically emit worldwide each year.
The team estimates that the 2023 wildfires potentially released between 69 to 183 tonnes of arsenic, a potent toxin associated with diabetes, cardiovascular disease, various cancers, and infant mortality, according to the World Health Organization. Arsenic can be transformed by wildfire and released into the environment from the soils that normally sequester it.
“Yellowknife has a decades-long history of mining, which has led to an accumulation of arsenic in the surrounding landscape,” announced Dr. Owen Sutton, a postdoctoral fellow in the Faculty of Environment at UWaterloo, in a statement. However, Yellowknife is not unique in this regard. Canada has many industrially contaminated sites that are vulnerable to wildfire.”
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The amount of arsenic released by wildfires depends on factors such as fire temperature, depth of the burn, and soil type. The researchers caution that in regions of the world where annual wildfires intersect with past or present mining and smelting operations, future fires could present a major risk for releasing stored toxins back into the environment, particularly as their frequency and severity are expected to increase due to climate change.
“While our research has raised the alarm on this issue, we will be the first to argue there is an urgent need for collaborative investigation by wildfire scientists, chemists, environmental scientists and policy experts,” said Dr. Colin McCarter, professor in the Department of Geography at Nipissing University and Canada Research Chair in Climate and Environmental Change. “By integrating diverse fire management techniques, including Indigenous fire stewardship, we can hopefully mitigate these emerging risks to human and environmental health.”
The researchers found that arsenic emissions from wetlands were the most concerning because of their tendency to store contaminants compared to forests. Moving forward, the team will continue to quantify the amount of toxins being stored by northern peatlands and study the potential release of other metals from those landscapes.
Dr. James Waddington, from McMaster University, also contributed to the work. “Globally-significant arsenic release by wildfires in a mining-impacted boreal landscape“, appears in Environmental Research Letters.
