Warming climate is turning rivers rusty with toxic metals

Warming climate is turning rivers rusty with toxic metals

Dozens of rivers and streams in Alaska are turning rusty orange, a likely consequence of thawing permafrost, a new study finds.

The Arctic is the fastest-warming region in the globe, and as the frozen ground below the surface melts, minerals once locked away in that soil are now seeping into waterways.

The permafrost thaw is exposing minerals to oxygen in a process known as weathering, which increases the acidity of the water and dissolves metals like zinc, copper, cadmium and iron – the most apparent metal that gives the rivers a rusty color visible even from satellite images. The study highlights the potential degradation of drinking water and risk to fisheries in the Arctic.

The phenomenon was first observed in 2018, when researchers noticed the milky orange appearance of the rivers across northern Alaska’s Brooks Range, a stark contrast to the crystal clear waters seen the year prior.

Within the year, a tributary of the Akillik river in Kobuk Valley national park saw the complete loss of two local fish species: the dolly varden and the slimy sculpin.