Alaska’s permafrost is melting and revealing high levels of mercury that could threaten Alaska Native peoples.  That’s according to a new study released earlier this month by the University of Southern California, analyzing sediment from melted permafrost along Alaska’s Yukon River. Researchers already knew that the Arctic permafrost was releasing some mercury, but scientists weren’t sure how much. The new study — published in the journal Environmental Research Letters — found the situation isn’t good: As the river runs west, melted permafrost is depositing a lot of mercury into the riverbank, confirming some of scientists’ worst estimates and underscoring the potential threat to the environment and Indigenous peoples.