At least 75 Alaska streams and streams have turned dirty orange, likely from thawing permafrost, with some rivers so affected the discoloration can be seen by satellite, a new study suggests.
The phenomenon, which researchers say comes amid unusually rapid warming in the region, was first observed in the northwestern state in 2018, scientists told Business Insider’s Jenny McGrath in January.
Researchers have been perplexed for years. But their findings, published Monday in the peer-reviewed journal Communications Earth & Environment, indicate that the rusty color of the streams likely comes from minerals uncovered by thawing.
Previously locked beneath Alaska’s permafrost, these minerals are now exposed to water and oxygen, causing them to release acid and metals like zinc, copper, iron and aluminum, according to the study.
Dissolved iron is thought to be the main culprit behind river “rusting,” which typically occurs in July and August, when the thaw is most pronounced.
But the implications of the merger go far beyond color. These waters become so acidic that some record pH levels of 2.6, between the acidity equivalent of lemon juice and orange juice.
Pure water has a pH of 7. Rivers and lakes typically have a pH of 6.5 to 8, and acid rain has a pH of 4.2 to 4.4.
A tributary of the Akillik River in Alaska’s Kobuk Valley National Park turned orange between 2016 (left) and 2018 (right). Jon O’Donnell/National Park Service
“These results have considerable implications for drinking water supplies and subsistence fishing in rural Alaska,” the researchers wrote.
They added that the region has already suffered the “total loss” of two fish species due to acidity: juvenile Dolly Varden trout and slimy sculpin. Chum salmon and whitefish are also at risk of population declines, they said.
The changes could be devastating for the region’s indigenous tribes, who rely heavily on fishing, the researchers noted.
The 75 orange streams observed were scattered across northern Alaska over a distance of about 600 miles, according to the study. All were in remote areas, miles from human activities that could impact the land, such as roads or mines.
The researchers highlighted satellite images of the Agashashok River, a tributary of the Kuguroruk River, and the Anaktok Creek tributary of the Salmon River in northwest Alaska. They said all three had become significantly redder during the summer months of the past 10 years.
An orange tributary joins the Kuguroruk River in Alaska. Joshua Koch, United States Geological Survey
Scientists warn that Alaska is warming at a rate two to three times the global average.
The Biden administration projected in November that the state would need about $4.8 billion in infrastructure repairs and adaptations over the next 50 years due to rising temperatures and flood damage, erosion and thawing of permafrost.
Alaska’s fishing and tourism industries, which collectively provide more than 90,000 jobs and $2.57 billion in wages, are also at risk, according to the administration’s multi-agency report, along with fish stocks. expected to collapse and winter tourism declining.
businessinsider
