A recent study published in the journal Communications: Earth and Environment reveals that dozens of streams and rivers in the remote regions of Alaska are turning from clear blue to a cloudy orange color. Researchers from the National Park Service, U.S. Geological Survey, University of California, Davis, and other institutions have identified 75 locations in northern Alaska’s Brooks Range where this phenomenon is occurring. This staining could be the result of minerals exposed by thawing permafrost, which has significant implications for drinking water and fisheries as the climate continues to change.
Lead author Jon O’Donnell, an ecologist for the NPS’ Arctic Inventory and Monitoring Network, first noticed the issue when he observed a river in 2018 that had turned rusty despite being clear the year before. With the help of helicopters, the researchers were able to access these remote rivers and streams to collect water samples. The stained rivers are so prominent that they can even be seen from space, indicating the extent of the problem. Assistant professor of environmental toxicology at UC Davis, Brett Poulin, noted that the staining resembled acid mine drainage, although no mines were located near these rivers.
The researchers hypothesize that as the permafrost thaws, mineral deposits are exposed to water and oxygen, leading to the release of acid and metals into the water. Samples taken from the affected waters showed highly acidic conditions with pH levels as low as 2.3, compared to the average pH of 8 for these rivers. This acidic water releases metals such as iron, zinc, nickel, copper, and cadmium, resulting in the characteristic orange color. The problem has been ongoing since at least 2008, as indicated by satellite images, and is slowly spreading from small headwaters into larger rivers over time.
The research team is currently in the second year of a three-year grant aimed at understanding the causes and implications of the stained rivers and streams. They are working to model which areas may be at risk, assess the impact on drinking water and fishing stocks, and understand how the changing climate is exacerbating the issue. The degradation of these water bodies is affecting habitat, water quality, and ecosystems, potentially leading to reduced fish and invertebrate populations. In the long term, rural communities reliant on these water sources may need treatment for drinking water, and local fishing stocks could be impacted.
As the climate continues to warm, permafrost thawing is expected to increase, potentially leading to more rivers turning orange and experiencing degraded water quality. The researchers emphasize the importance of further study to better understand the extent of the problem and whether these rivers and streams can recover, especially if colder weather promotes permafrost restoration. Collaboration from various institutions, including Alaska Pacific University, Colorado State University, University of Alaska Anchorage, and UC Riverside, contributed to the research. Funding for the study came from the U.S. Geological Survey-NPS Water Quality Partnership Program, U.S. Geological Survey Changing Arctic Ecosystem Initiative, and the NPS Arctic Inventory and Monitoring Program.
