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Thawing permafrost in Alaska is staining rivers orange, impacting water quality and ecosystems.
In Alaska, numerous remote streams and rivers are shifting from their natural crystal-clear blue to an unsettling cloudy orange. According to a recent publication in the Nature journal Communications: Earth and Environment, this could be caused by minerals exposed by thawing permafrost.
In a collaborative research effort, a team of scientists from the National Park Service, U.S. Geological Survey, the University of California, Davis, and other institutions have documented and sampled these impaired waters, identifying 75 locations across an area as large as Texas in northern Alaska’s Brooks Range.
Implications of Water Quality Degradation
The degradation of these water bodies could significantly impact drinking water and fisheries in Arctic watersheds as the climate continues to change. “The more we flew around, we started noticing more and more orange rivers and streams,” said lead author Jon O’Donnell, an ecologist for the NPS’ Arctic Inventory and Monitoring Network. “There are certain sites that look almost like a milky orange juice.” He notes that these orange streams pose risks of toxicity and may obstruct fish migration to spawning areas.
Discovery and Analysis of Stained Rivers
O’Donnell first noticed the issue when he visited a river in 2018 that appeared rusty despite being clear in the previous year. He began asking around and compiling locations while collecting water samples when possible in the remote region, where helicopters are generally the only way to access the rivers and streams.
“The stained rivers are so big we can see them from space,” said Brett Poulin, an assistant professor of environmental toxicology at UC Davis who was a principal investigator in the research. “These have to be stained a lot to pick them up from space.” Poulin, who specializes in water chemistry, said the staining resembled the effects of
Analyzing Water Samples and Metal Concentrations
Some samples from the impaired waters have a pH of 2.3 compared to the average pH of 8 for these rivers. This means the sulfide minerals are weathering, resulting in highly acidic and corrosive conditions that release additional metals. Elevated or high levels of iron, zinc, nickel, copper, and cadmium have been measured.
“We see a lot of different types of metals in these waters,” Evinger said. “One of the most dominant metals is iron. That’s what is causing the color change.”
While O’Donnell first noticed a change in 2018, satellite images have turned up stained waters dating back to 2008. “The issue is slowly propagating from small headwaters into bigger rivers over time,” he said. “When emergent issues or threats come about, we need to be able to understand them.”
Ongoing Research and Future Concerns
The researchers are in the second year of a three-year grant aimed at understanding what is happening in the water, modeling what other areas may be at risk, and assessing implications for drinking water and fishing stocks.
The problem is growing and affecting habitat, water quality, and other ecological systems, turning healthy areas into degraded habitats with fewer fish and DOI: 10.1038/s43247-024-01446-z
Scientists from Alaska Pacific University, Colorado State University, University of Alaska Anchorage, and UC Riverside also contributed to the research.
The research was funded by U.S. Geological Survey–NPS Water Quality Partnership program, the U.S. Geological Survey Changing Arctic Ecosystem Initiative, and the NPS Arctic Inventory and Monitoring Program.