Scientists have found new evidence that melting Arctic permafrost could unleash large sums of mercury, a dangerous toxin.
Scientists estimate that the amount of mercury in the atmosphere has grown sevenfold over the last 500 years, primarily from burning coal. Air currents are carrying airborne mercury toward the Arctic, where it is absorbed by plants, which then deposit the toxin in the soil. Over centuries, mercury has built up in the frozen ground, such that today, Arctic permafrost may hold more mercury than the atmosphere, the oceans, and every living organism combined. As the region warms, melting permafrost could liberate this buried mercury.
“There could be this giant mercury bomb in the Arctic waiting to explode,” said Josh West, an environmental scientist at the University of Southern California and coauthor of the new study.
Still, experts are uncertain how much mercury may be lurking in the Arctic, or how much is now flowing into waterways as permafrost begins to thaw. To shed light on the matter, scientists recently measured the toxin in riverbanks and sandbars on the Huslia and Yukon rivers in Alaska. Troublingly, their measurements lined up with the high end of previous estimates. Their findings were published in the journal Environmental Research Letters.
The good news, scientists say, is that some of the mercury unleashed by permafrost is being buried in river sediment, though it’s not clear how much is being locked away. Lead author Isabel Smith, of the University of Southern California, warned that rising Arctic mercury levels “could take a huge toll on the environment and the health of those living in these areas.”
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