Scientists discover enormous reserves of mercury in permafrost

Scientists have uncovered another hidden threat buried in the icy frozen north—massive natural reserves of mercury, a toxic heavy metal that in some forms can build up in fish and other animals and cause serious health problems in humans.

A study published Monday in the journal Geophysical Research Letters reports that the amount of natural mercury bound up in Arctic permafrost may be 10 times greater than all the mercury humans have pumped into the atmosphere from coal-burning and other pollution sources over the last 30 years. As climate change warms the land, this thawing permafrost could release significant quantities of mercury back into the environment, potentially allowing far more of the pollutant to build up in the atmosphere and the food web.

“Prior to the start of the study, people assumed permafrost contained little to no mercury,” says study co-author Kevin Schaefer of the National Snow and Ice Data Center at the University of Colorado. “But it turns out that not only is there mercury in permafrost, it’s also the biggest pool of mercury on the planet.”

Put another way, says lead author Paul Schuster, a U.S. Geological Survey hydrologist, “This is a complete game-changer for mercury. It’s a natural source, but some of it will be released through what we’re doing with climate change.”

What’s not yet clear, however, is how much mercury could be released, or when, in a form that is toxic to humans.

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