More than 200 rivers and streams in Alaska have exhibited bright orange plumes in the water. Since 2019, researchers have found that the water was even more acidic and metallic than the water that leaches from metal mines. Many of these rivers and streams are within national parks and preserves, so these are pristine watersheds, not places where mining activities took place.
Researchers have attributed the rusty-colored water to thawing permafrost, which is occurring more and more as the climate warms. Water trickles into the ground and encounters minerals that have been trapped in the previously frozen soil for countless millennia. The interaction releases iron, sulfuric acid, and other metals into nearby streams. This turns the water orange and poses threats to plants, wildlife, and people.
The onset of the phenomenon across the region was in 2019, coinciding with Alaska’s hottest summer to date at that time followed by a snowy winter. A thick layer of snow insulates the soil, preventing the permafrost from refreezing. Water then seeps deeper into the thawing soil and interacts with minerals.
To date, there are no documented adverse impacts from the acid rock drainage into remote streams, but there are still concerns. These toxic contaminants in rivers and streams can be transported very long distances.
The Arctic is warming much faster than the rest of the world. This particular consequence of the warming climate was not predicted or included in assessments of how the Arctic will change. However, it is happening in rivers across the Arctic including ones in Boreal and Arctic Canada and in other parts of the world where there is permafrost.
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References:
Alaska’s Orange Rivers More Metallic Than Acid Mine Drainage
