POPULAR MECHANICS - For the past several years, dozens of rivers throughout the Arctic watershed have been undergoing a shocking transformation: They’re turning orange. When rivers sport these troubling hues, humans are usually the culprit—whether through mining operations, agricultural runoff, or criminally dumping hazardous materials into waterways. With these rivers mostly tucked away in northern Alaska, humans aren’t the direct cause of this aquatic orange-ification, but we’re also not totally off the hook. Sadly, all roads lead back to anthropogenic climate change.
A team of researchers from the University of California, Riverside (UC Riverside) recently published a paper on their analysis of the Salmon River located in the Brooks Range in northern Alaska, detailing the step-by-step process that lead from rising Arctic temperatures to these orange rivers. According to the study, published in the journal PNAS, warming permafrost—the permanently frozen ground that underlies upwards of 85 percent of Alaska’s landmass—invites water and oxygen to interact with sulfide-rich rocks like pyrite. This creates an abundance of sulfuric acid, which leeches naturally occurring metals such as iron, cadmium, and aluminum into the river.
Although small amounts of metals in rivers can be safe, these incredibly high concentrations exceed the Environmental Protection Agency’s toxicity levels for aquatic life. They also turn the water orange, making the area look more like a human-made ecological disaster than a natural river.
“This is what acid mine drainage looks like,” UC Riverside’s Tim Lyons, senior author of the study, said in a press statement. “But here, there’s no mine. The permafrost is thawing and changing the chemistry of the landscape.”