Due to permafrost thawing, rivers in Alaska are changing color and becoming contaminated with metals, the concentration of which has increased 70-fold in some areas. Scientists warn that this process threatens aquatic ecosystems and local communities. LRT reports this, citing ScienceAlert, writes UNN.
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In recent years, researchers have observed an unusual phenomenon in Alaska’s Brooks Range: once-clear rivers and lakes are gradually acquiring a rust-brown hue. The cause may be warming, which is thawing soils that have remained frozen for thousands of years.
Water penetrates thawed rock and leaches iron, aluminum, manganese, zinc, nickel, cadmium, and other elements from it. As a result of chemical reactions, these substances enter rivers, changing their color and composition.
In some rivers, the water has become more acidic than mine drainage
In 2022–2024, scientists studied water in six Alaskan river basins. Some samples were more acidic and contained higher concentrations of metals than mine wastewater.
Particularly alarming levels were recorded in the Salmon River, where one contaminated stream increased metal concentrations 70-fold compared with normal levels.
Researchers link the sharp deterioration in water quality to the record-hot summer of 2019. Afterward, sulfate and zinc concentrations in the rivers rose significantly.
Since 2018, similar phenomena have been recorded in more than 200 rivers and streams across North America. Scientists warn that the contamination may cause vegetation die-offs and declines in populations of salmon, whitefish, and other aquatic animals.
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