This story originally was watching News from the Highlands and is part of climate desk Cooperation.
Dozens of once-crystal-clear streams and rivers in arctic Alaska are now bright orange and cloudy, and in some cases are turning more acidic. This otherwise undeveloped landscape now looks like an industrial mine has been in operation for decades, and scientists want to know why.
Roman Dial, a professor of biology and mathematics at Alaska Pacific University, first noticed the sharp changes in water quality while conducting fieldwork in the Brooks Range in 2020. He spent a month with a team of six graduate students and they could not find adequate drinking water. “There are so many streams that aren’t just patchy, they’re so acidic they’ll curdle your milk powder,” he said. In others, the water was clear, “but you couldn’t drink it because it had a really weird mineral taste and smell.”
Dial, who has spent the past 40 years studying the Arctic, collected data on climate change-related changes in Alaska’s tree line for a project that also includes work by ecologist Patrick Sullivan, director of the university’s Institute for the Environment and Natural Resources Alaska Anchorage and Becky Hewitt, Professor of Environmental Studies at Amherst College. Now the team is getting to the bottom of the secret of water quality. “I feel like I’m a graduate student again in a lab I don’t know about, and I’m fascinated by it,” Dial said.
Most of the rusting waterways are in some of Alaska’s most remote protected areas: the Arctic National Wildlife Refuge, Gates of the Arctic National Park and Preserve, Kobuk Valley National Park, and Selawik Wildlife Refuge.
The phenomenon is visually striking. “It seems like something has been broken up or exposed in a way that has never been exposed before,” Dial said. “All the hard rock geologists looking at these images are like, ‘Oh, that looks like sour Mine waste.’” But it’s not mine waste. According to the researchers, the rusty coating on rocks and river banks comes from the land itself.
The prevailing hypothesis is that global warming will cause the underlying permafrost to degrade. This releases iron-rich sediments, and when these sediments encounter flowing water and open air, they oxidize and turn a deep rust-orange color. The oxidation of minerals in the soil can also make the water more acidic. The research team is still early in identifying the cause in order to better explain the consequences. “I think the pH issue” — the acidity of the water — “is really alarming,” Hewitt said. While pH regulates many biotic and chemical processes in streams and rivers, the exact effects on the intricate food webs that exist in these waterways are unknown. From fish to stream bed bugs to plant communities, the research team isn’t sure what changes might result.
The rusting of Alaska’s rivers is likely to impact human communities as well. Rivers such as the Kobuk and Wulik, where rusting has been observed, also serve as sources of drinking water for many predominantly Alaskan communities in Northwest Alaska. A major concern, Sullivan said, is how water quality, if it continues to deteriorate, could affect the species that serve as the primary food source for Alaska Natives, who lead a subsistence lifestyle.
https://www.wired.com/story/alaskas-arctic-waterways-are-turning-a-foreboding-orange/ Alaska’s Arctic Waterways Are Turning a Foreboding Orange