mountain rivers in the US state of Colorado are rusting and the warming climate is to blame, according to research. There was also an increase in toxic heavy metals observed in Arctic currentsleading to concern that this phenomenon may be more widespread.
From the Andes to the European Alps, researchers have seen an increase in heavy metals in mountain streams in recent decades, but it wasn’t clear what was driving the trend. By analyzing 40 years of water chemistry data from 22 of Colorado’s mountain streams, researchers found that concentrations of copper, zinc and sulfate have doubled over the past 30 years. The study, published in Water Resources Researchfound that drier weather and reduced streamflow accounted for about half of the increase, but the remaining increase was most likely due to the thawing of subsurface ice, exposing more rock to groundwater and releasing the metals it contained .
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Dilution of the metal-rich water means the contamination is unlikely to be a significant concern by the time it reaches cities and fields further downstream, but for mountain communities the water may need additional treatment to make it safe. And as the climate continues to warm, the problem is likely to accelerate and affect a greater number of communities around the world.
