Scientists have found new evidence that melting Arctic permafrost could unleash large sums of mercury, a dangerous toxin linked to brain damage in children and heart disease in adults.
Scientists estimate that the amount of mercury in the atmosphere has grown sevenfold over the last 500 years, primarily from burning coal. Air currents carry mercury pollution toward the Arctic, where it is absorbed by plants, which deposit the toxin in the soil when they die. 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. Now, as the region warms, melting permafrost is beginning to liberate the toxin.
“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 as to exactly how much mercury may be lurking in the Arctic, or how much is now flowing into waterways as permafrost melts. To shed light on the matter, scientists 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 study was published in the journal Environmental Research Letters.
The good news, scientists say, is that rivers may be reburying some of the mercury unleashed by thawing permafrost, though it’s not clear how much of the toxin is actually being locked away. Lead author Isabel Smith, also 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.”
ALSO ON YALE E360
Rain Comes to the Arctic, With a Cascade of Troubling Changes
