As Arctic Soils Thaw, Releases Of Iron And Other Metals Wiping Out Life In Entire Rivers And Streams

When ecologist Patrick Sullivan flew into the Salmon River in Alaska to conduct a vegetation study in the summer of 2019, he was excited about paddling down the pristine Arctic river. Before he and his colleague got there, however, the pilot warned that they might not see what John McPhee had described, in his best-selling book Coming Into the Country, as the “purest water I have ever seen.” Even then, Sullivan was not prepared for the river that eventually came into view. For as far as the eye could see, the water flowed bright orange. Research would later reveal that it was too toxic for fish, most other forms of aquatic life, and shoreline vegetation to survive.

“It was a shock,” Sullivan recalls. “The pilot told us that [the river] was clear the year before. And we have photographic evidence that shows that it was clear in 2017.” Until relatively recently, a small scattering of rivers stained by the oxidation of iron and other heavy metals could be found throughout the circumpolar world. But over the last decade, the number of rusting or yellowing rivers has been increasing dramatically, and researchers are scrambling to determine where, when, and how the phenomenon is affecting fish and other wildlife, the drinking water that Indigenous people depend on, and whether there will be an end to its expansion throughout the Arctic.

What scientists do know is that the chemistry behind this rusting is inextricably linked to the climate-induced thawing of permafrost, an increase in rainfall that is also triggered by warming, and the landslides and ground slumping set in motion by those impacts.Since at least 2019, the rusting and other similar river discolorations have spread to more than 200 rivers in Alaska, a growing number of rivers in the Yukon and Northwest Territories, and as far north as the Arctic Archipelago. The pH levels in some rivers have dropped to 2.3, comparable to the acidity of vinegar.

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In Alaska, the most recent satellite imagery indicates that the affected rivers now cover an area more than 600 miles wide, according to Abagael Pruitt, a researcher in the department of environmental toxicology at University of California, Davis who is, with O’Donnell and the National Park Service, studying the impacts of thawing permafrost. Canadian scientists have detected rusting in the Peel and Mackenzie River watersheds in the Yukon and in the Northwest Territories. Yukon Geological Survey hydrologist Benoit Turcotte came upon this phenomenon serendipitously while conducting erosion studies along the Ogilvie and East Blackstone rivers in the Peel River watershed in recent years. The Peel flows into the Mackenzie, Canada’s longest river.

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https://e360.yale.edu/features/rusting-rivers