The coloring in dozens of Alaska's most isolated streams and rivers is changing from a bright blue to a rusty orange, and the cause may be minerals that have been exposed by thawing permafrost.
Thawing Permafrost
The Arctic is warming at the fastest rate on Earth, and as the ice melts, minerals that were previously contained in the soil are now leaking into rivers.
A recent study shows that the affected water is on federal property, including national parks like Kobuk Valley and Gates of the Arctic.
Researchers collected water samples from 75 sites in the Brooks mountain range of northern Alaska, an area roughly equivalent to Texas. Helicopters are the only means of access to several of the tested regions because they are so far away.
The orange rivers may be seen from space because the stained areas are so big.
Experts found the milky orange color of the rivers across northern Alaska's Brooks Range in 2018, marking the first observance of the phenomenon, in stark contrast to the crystal clear waters seen the year before.
"Those orange streams can be problematic both in terms of being toxic but might also prevent migration of fish to spawning areas," lead author Jon O'Donnell, an ecologist for the National Park Service Arctic Inventory and Monitoring Network,
According to scientists, when the environment warmed, minerals that had been frozen in permafrost were released. Acid and metals were released from the metal ores when they were exposed to air and water.
The contaminated water included high or elevated amounts of iron, zinc, nickel, copper, and cadmium, according to sample results. One of the most prevalent metals, iron, is thought to be the cause of the orange coloring.
The usual pH of rivers is 8, therefore the impacted water is noticeably more acidic than the other water samples, some of which had a pH of 2.3.
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Potential Danger
The potential threats to drinking water and fisheries are currently being investigated by experts. The research did indicate that "stream discoloration was associated with dramatic declines in macroinvertebrate diversity and fish abundance."
A diversity of species found in Alaska's Arctic rivers are "critical for subsistence, sport, and commercial fisheries," according to research findings. Those fish could be in danger from iron and other harmful metals in the water.
Two native fish species, the slimy sculpin and the dolly varden, completely vanished from a tributary of the Akillik river in Kobuk Valley National Park within the same year.
Drinking water in rural areas may be impacted by metals in the water. According to researchers, they could, at the very least, affect the flavor of the water, necessitating improved water filtration in rural areas.
"When mixed with another river, it can actually make the metals even more potent [in their] impact on aquatic health," said Brett Poulin, study author and assistant professor of environmental toxicology at the University of California, Davis.
The research team disclosed that, in order to guarantee that local people receive accurate information on the emerging occurrence, they were actively collaborating with tribe liaisons in Alaska.
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