"Orange rivers signal toxic shift in Arctic wilderness Warming soil unleashes metals deadly to fish and food chains

[orleans]

In Alaska’s Brooks Range, rivers once clear enough to drink from now run orange and hazy with toxic metals. As warming thaws formerly frozen ground, it sets off a chemical chain reaction that is poisoning fish and wreaking havoc on ecosystems.

As the planet warms, a layer of permafrost — permanently frozen Arctic soil that locked away minerals for millennia — is beginning to thaw. Water and oxygen creep into the newly 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.

Often times, geochemical reactions like these are triggered by mining operations. But that is not the case this time.

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“There’s no fixing this once it starts,” Lyons said. “It’s another irreversible shift driven by a warming planet.”

https://news.ucr.edu/articles/2025/09/08/orange-rivers-signal-toxic-shift-arctic-wilderness