This story is originally appeared High Country News and is a part Climate Table cooperation.
Dozens of streams and rivers in Arctic Alaska that were once crystal clear now flow bright orange and cloudy, and in some cases are becoming more acidic. This otherwise undeveloped landscape looks as if an industrial mine has been operating 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 doing fieldwork in the Brooks Range in 2020. He spent a month with a team of six graduate students and they couldn’t find it. adequate drinking water. “There are so many streams that aren’t just blotchy that they’re so acidic that they cut through your powdered milk,” he said. In others, the water was clear, “but you couldn’t drink it because it had a really weird mineral taste and sharpness.”
Dial, who has spent the last 40 years exploring the Arctic, has been collecting data on climate change-driven changes in Alaska’s tree line for a project that includes the work of ecologist Patrick Sullivan, director of the University’s Institute of Environment and Natural Resources. Becky Hewitt, associate professor of environmental studies at Alaska Anchorage and Amherst College. Now the team is investigating the water quality mystery. “I feel like I’m a graduate student again in a lab I know nothing about, and I’m very impressed with it,” Dial said.
Most of the rusting waterways are located in Alaska’s most remote protected lands: Arctic National Wildlife Refuge, Arctic National Park and Preserve Gates, Kobuk Valley National Park, and Selawik Wildlife Refuge.
The phenomenon is visually stunning. “Something seems to have been cracked open or exposed in a way that has never been exposed before,” Dial said. “All the hard rock geologists who look at these pictures say, ‘Oh, that looks like acid mine tailings’.” But this is not my horse. According to the researchers, the rusty coating on rocks and river banks comes from the soil itself.
The prevailing hypothesis is that climate warming is causing degradation of the underlying permafrost. This releases iron-rich deposits that oxidize and turn a dark rusty orange color when these deposits hit running water and open air. Oxidation of minerals in the soil may also be making the water more acidic. The research team is just in the early stages of determining the cause to better explain the results. “I think the pH issue”—the acidity of the water—“is really worrisome,” Hewitt said. While pH regulates many biotic and chemical processes in streams and rivers, its precise effects on the complex food webs found in these waterways are unknown. The research team isn’t sure what changes might result, from fish to insects and plant communities in the riverbed.
The rusting of Alaska’s rivers will also have a major impact on human communities. Rivers such as the Kobuk and Wulik, where rusting has been observed, also serve as drinking water sources for the predominantly Alaska Native communities in Northwest Alaska. Sullivan said one of the biggest concerns is how if water quality continues to deteriorate, it could affect the species that serve as the main food source for Alaska Natives who live a subsistence lifestyle.