2023-12-30 22:41:38
Experts at the United States Geological Survey (Usgs) have not yet solved the mystery of Alaska’s rivers and streams, which are turning increasingly orange.
Iron-containing minerals appear to be to blame for the oxidation of waters, but it is still unclear why more and more rivers and streams are affected, Scientific American reports.
One of the rivers with the most rusty water is the Kobuk, in northwest Alaska, which has a length of 451 kilometers. In recent years, researchers have observed that the Kobuk and numerous streams around it are becoming increasingly orange.
Analyzes have recorded a higher concentration of iron, less dissolved oxygen and high levels of acidity in these aquifers. The pH of some small rivers reaches 3.5 points, which is even more acidic than orange juice.
So what is the reason? One of the leading theories is that rising temperatures in the region are causing permafrost to melt, releasing iron locked in frozen soils.
The Arctic is warming almost four times faster than the rest of the world, and northern Alaska is no exception.
Another possibility is that bacteria and complex geochemical processes are to blame for river oxidation. Mineral iron, unlike oxidized iron, is soluble in water.
When groundwater transports it to an oxygenated stream, it oxidizes once more, turning the stream orange, according to the Scientific American report.
Whatever the reason, scientists agree on one thing: Rising temperatures have awakened many geochemical processes that had, in fact, been inhibited for 5,000 years, when the ground was frozen, said ecologist David Cooper.
Rusty rivers may seem very strange, but this effect of iron on Earth’s water systems is not uncommon.
For example, in early 2023, astronauts aboard the International Space Station observed that the Betsiboka River delta in Madagascar had turned a deep red color due to iron-rich sediments in its waters.
Another example of this is a place known as Bloody Falls, in Antarctica. In this place, it seems as if blood is flowing from the ice. A century ago, explorers who spotted this phenomenon thought the vibrant color was due to red algae.
However, a recent study found that ‘blood falls’, as they are known, contain many iron-rich nanospheres that turn red when oxidized.
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