TechAlaska's rivers "bleed" rusty red amid historic permafrost thaw

Alaska's rivers "bleed" rusty red amid historic permafrost thaw

Observation map of "rusting" streams in Arctic Inventory and Monitoring Network (ARCN) parks in northern Alaska
Observation map of "rusting" streams in Arctic Inventory and Monitoring Network (ARCN) parks in northern Alaska
Images source: © USGS

11:36 AM EST, December 27, 2023

Scientists from the United States Geological Survey (USGS) tackled the mystery of Alaska's reddening rivers. They analyzed the biochemistry of the rust-colored water and further investigated the extent of this occurrence.

Reddening waters in Alaskan rivers

The reddened waters in these streams differ significantly from their clear-water neighbors. These streams contain less oxygen, significantly more iron, and are highly acidic.

This is characteristic of rivers that turn orange or even rusty, a sanguinary hue as they come into contact with sediments with a high iron concentration. Although this phenomenon occurs globally, it is particularly noticeable in Alaska.

Permafrost thaw polluting Alaskan rivers

Rivers in Alaska that are fed by permafrost are turning red. Intense thawing could lead to a release of iron that was previously contained in the soil.

Furthermore, the river does not have to be in direct contact with the thawed soil. The historic thaw allows for increasingly more bacteria to penetrate the permafrost. These bacteria may carry large amounts of iron from the frozen ground into the groundwater. If such a mixture finds its way into oxygen-rich streams, it could potentially trigger the production of iron oxide, which imparts a rusty color to the rivers.

Related content