In 1977, author John McPhee wrote his nonfiction classic “Coming into the Country.” It describes how he and a group of men canoed the Salmon River in the Brooks Range of Alaska to assess its potential for Wild and Scenic status—a designation that would provide long-term federal protection. On their trip, they found abundant Arctic grayling (Thymallus arcticus), chum salmon (Oncorhynchus keta)—and as McPhee writes, “the clearest, purest water I have ever seen flowing over rocks,” which allowed them to “see down 15 feet in pools.”
In Alaska’s Brooks Range, rivers once clear enough to drink from now run orange and hazy with toxic metals. | Credit: Taylor Roades
Not anymore. These days, the Salmon River runs orange—contaminated with toxic metals. Not because of acid mine drainage—although the water has the same ocher color—but because of climate change. According to new research from the University of California, Riverside, permafrost—the frozen Arctic soil that has locked away minerals for thousands of years—is beginning to thaw with a warming planet. As it thaws, water and oxygen creep into the exposed soil, triggering the breakdown of sulfide-rich rocks and creating sulfuric acid that leaches naturally occurring metals like iron, cadmium, and aluminum from rocks into the river, which poisons fish and damages ecosystems.
According to a press release, the team’s analysis confirmed that thawing permafrost was unleashing geochemical reactions that oxidize sulfide-rich rocks like pyrite, generating acidity and mobilizing a wide suite of metals, including cadmium, which accumulates in fish organs and could affect animals like bears and birds that eat fish. The authors say that levels for several of the metals exceed EPA toxicity thresholds for aquatic life. Additionally, the cloudy water reduces the amount of light reaching the bottom of the river and smothers insect larvae that salmon and other fish eat.
According to the study, the Salmon River is not alone. A recent inventory in the same mountain range identified 75 streams that have recently turned orange and turbid. The authors say it’s likely happening across the Arctic. Wherever there’s the right kind of rock and thawing permafrost, the process can start. Unfortunately, co-author, Tim Lyons, said once it starts, it can’t be stopped, calling it “another irreversible shift driven by a warming planet.”
The study was published in the Proceedings of the National Academy of Sciences.
CLICK HERE FOR MORE INFORMATION
https://h2oradio.org/this-week-in-water/a-high-five-for-the-high-seas
GET WET! 