The rivers in the Arctic have turned into "orange juice", but it's even more sour than orange juice! The fish are dying of sourness

Image source: medium

Alaska is a place with magnificent natural scenery, but scientists have recently discovered that the rivers there are becoming more and more "orange" . One of the rivers is the most orange, the Kobuk River (pictured below), which winds through northwestern Alaska for about 451 kilometers.

Image credit: Taylor Roades

The river looked polluted, as if it had been filled with carrot juice, and its surface shimmered with a gasoline-like rainbow luster.

In order to understand why the water here has turned color, scientists came to Alaska to study the water quality of different river basins. When scientists used a pH tester to check the pH value of the rivers, they found that the pH values ​​of these rivers were extremely low, with the lowest pH value being only 3.5 , which is much lower than orange juice, which is also orange, and humans cannot drink it at all.

Image credit: Taylor Roades

Originally, rivers in such remote areas should not be affected by environmental pollution. In 1975, when writer John McPhee was traveling by boat on a river in Alaska, he said, "This is the clearest and purest water I have ever seen." But now the more than 110-kilometer-long river here is "rusty." In the orange river water, scientists have found a large amount of iron oxide minerals, which also contain a large amount of acidic substances.

Image credit: Taylor Roades

Why do Alaskan rivers contain so much iron oxide?

Scientists believe that climate change is the main reason for this . Rising temperatures in the region cause permafrost to melt, releasing iron that was previously locked in the frozen soil. When the river passes through the land containing iron, the iron reacts with the air and water to form what we commonly know as rust. It is this rust that makes the river water look orange. Imagine that the water is flowing through a huge rusty iron gate, and the water is naturally dyed.

Orange watershed image source: USGS/Public Domain

The Arctic is warming nearly four times faster than the rest of the world, and northern Alaska is no exception. Kobuk Valley National Park in Alaska has already warmed 2.4 degrees Celsius since 2006 and could reach an additional 10.2 degrees Celsius by 2100, higher than any other national park projected.

However, there is another view that the orange color comes not only from iron, but also from microorganisms. Some scientists believe that during the thawing process of permafrost, some microorganisms hidden in the permafrost are released and revived, and then absorb the iron in the soil. In any case, it is related to iron.

Image source: Internet

With such high concentrations of iron and acid in the river, the fish in the water naturally cannot survive. A pH of about 7 is the neutral point for water, and many fish live most comfortably in waters close to this pH. Of course, some fish, such as many tropical fish species in the Amazon River basin, have adapted to slightly acidic water environments.

When biologist Mike Carey flew to Alaska by helicopter in August 2018 to retrieve a water sensor, he found that the streams there were almost devoid of fish or other insects.

For salmon, under acidic or alkaline conditions, they may face multiple physiological stresses, which may lead to reduced growth, reduced reproductive capacity, and even death.

Iron oxide in the water also has a great impact on their survival because iron oxide particles may be deposited on the gills of fish, affecting their breathing. Gills are organs that fish use to extract oxygen from water. If the gills are blocked, fish may have difficulty getting enough oxygen, leading to suffocation.

Image source: Internet

If the fish can't survive, the lives of local fishermen will naturally be affected.

First, pollution can lead to a decrease in the number of fish, especially sensitive species such as salmon. This directly affects the fishermen's catch and income. Even if the fish survive, pollution may affect their quality, as heavy metals and other toxic chemicals may accumulate in the fish, posing health risks to people who eat these fish, thereby reducing market demand and sales prices.

There is actually a similar phenomenon in Antarctica, and it looks more terrifying than the orange river in the Arctic, like a blood waterfall. In Taylor Glacier in Antarctica, dark red liquid emerges from cracks on the surface of the glacier, soaking the surrounding ice surface, and seems to be frozen blood oozing out of humans.

Image credit: Peter Rejcek/NSF/Public Domain

The reason for the Blood Falls is the high concentration of iron ions, which is much higher than the iron ions in the orange rivers of the Arctic . The high concentration is caused by the concentration of salt during the crystallization of ancient seawater. Due to the heat exchange between the huge ice blocks of the glacier and the trapped liquid seawater, the pure ice crystallized and expelled the dissolved salts during the cooling process, causing salt condensation in the deep residual seawater.

Not only in the Antarctic and the Arctic, but also in other places, rivers affected by iron have been seen. In early 2023, astronauts on the International Space Station (ISS) saw a red river visible to the naked eye on Earth, located in the Betsiboka River Delta in Madagascar, where the water is rich in iron sediments, so it turns a rich red.

Image credit: ISS/NASA

Image credit: ISS/NASA

Have you ever seen a river that looks like orange juice?

References

[1]https://www.usgs.gov/centers/alaska-science-center/science/rusting-arctic-rivers-freshwater-ecosystems-respond-rapidly#overview

[2]hhttps://www.scientificamerican.com/article/why-are-alaskas-rivers-turning-orange/

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