Arctic, permafrost thaw has released toxic metals into rivers

The thawing of permafrost in the Arctic is releasing toxic metals that end up in rivers: between 2019 and 2020, zinc levels up to 70 times higher than normal were detected, making the rivers highly acidic and rust-colored. This is according to a study led by Taylor Evinger of the University of California, Davis, published in the journal AGU Advances, which analyzed the impact of climate change in Alaska. The thawing of the previously permanently frozen ground, known as permafrost, is causing minerals that were previously trapped in the soil to be exposed to air and water, triggering chemical reactions that have led to the release of sulfates and metals into the rivers. The analysis was conducted on six watersheds in northwestern Alaska and showed a peak in activity between 2019 and 2020, coinciding with unusually warm and snowy winters. During the same period, increases in sulfate concentrations of up to 263% and zinc of up to over 700% were recorded, with more than 200 waterways affected. Very high levels of iron, aluminum, nickel, zinc and cadmium were also recorded in the rivers, with pH values dropping as low as 2.5. According to the study, heavy metals and sulfates can travel more than 100 kilometers downstream, posing potential dangers both to aquatic ecosystems and to rural communities that use those waters. The phenomenon, the authors of the research emphasize, risks worsening further in the coming years and could affect increasingly large regions. Reproduction reserved © Copyright ANSA