'Massive' mercury reserves hidden in Arctic permafrost
Tuesday, March 6, 2018, 20:17 - A new survey of the world's Arctic regions suggests they host the largest concentration of mercury on the planet, raising dire questions of what happens as climate change continues to trigger permafrost melting.
The scientists drilled into the northern Alaska permafrost at 13 sites from 2004 to 2012, and used their findings to estimate total mercury levels in the Arctic zones of our planet. What they found was astonishing: Around 793 gigagrams, or almost 60 million litres, of mercury resides in frozen northern permafrost, which the scientists say is around 10 times the amount of mercury from human sources emitted over the last three decades. Factor in mercury in unfrozen northern permafrost as well, and that number rises to 1,656 gigagrams of mercury, "nearly twice as much mercury as soils outside of the northern permafrost region, the ocean and the atmosphere combined."
The discovery gives a clearer picture of what might happen if climate change continues and the thaw of permafrost lands, previously frozen year-round, accelerates. As it is, some scientists have been sounding the alarm for years about the release of methane from melting permafrost -- a greenhouse gas even more potent than CO2.
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Though mercury is a naturally occurring compound, if it leaches into the surrounding ecosystem and food chains in high enough concentrations, it becomes toxic, particularly when combined into methylmercury.
"There would be no environmental problem if everything remained frozen, but we know the Earth is getting warmer," Paul Schuster, lead author of the study, said in a news release. "Although measurement of the rate of permafrost thaw was not part of this study, the thawing permafrost provides a potential for mercury to be released — that’s just physics."
The effects of a rise in mercury release aren't well known just now, but the research is still of concern to people who rely on northern ecosystems.
"It's a very big concern for rural communities and anyone who relies on subsistence food resources like the salmon," Edda Mutter, the science director of the Yukon River Inter-Tribal Watershed Council, which includes indigenous people in both Canada and Alaska, said in an interview with CBC News.
The study was published last month in the journal Geophysical Research Letters.