Alaska’s rusting rivers are proving to be a bit of a conundrum for scientists at the United States Geological Survey (USGS). Iron-bearing minerals appear to be the culprit, but the reason behind their increasing abundance is not totally clear.
In recent years, researchers
To understand the carrot-colored waters, the USGS partnered with the National Park Service, the University of California-Davis, the University of Alaska-Anchorage, and Alaska Pacific University. Their teams of scientists set out to map the extent of the orange waterways, learn about its impact on the wider ecosystem, and answer the question of what’s causing the color change.
Their research has revealed that the orange streams have higher concentrations of iron, less dissolved oxygen, and more acidic water than nearby clearwater streams. According to
So, what’s the cause? One leading theory is that rising temperatures in the region are causing permafrost to thaw, releasing iron that was previously locked up in the frozen soils. The Arctic has warmed
Another idea is that bacteria and complex geochemical processes could be to blame. The thaw of permafrost may be allowing bacteria to start reducing oxidized iron in the soil. Once groundwater carries it into an oxygenated stream, it becomes oxidized again and takes on this vibrant orange shade.
Rising temperatures have “really awakened a lot of these geochemical processes that have been basically stalled out for 5,000 years because the ground’s been frozen,” David Cooper, an ecologist at Colorado State University, told Scientific American.
Rusting rivers may look otherworldly, but it’s not uncommon for iron to have this impact on Earth’s water systems. Earlier this year, astronauts onboard the International Space Station (ISS) saw how the Betsiboka River Delta in Madagascar had
On the opposite side of the planet to the Arctic, there’s a site known as the