Credit: Jean-François BoilyIce can dissolve iron minerals more effectively than liquid water, according to a new study from Umeå University. The discovery could help explain why many Arctic rivers are now turning rusty orange as permafrost thaws in a warming climate. The study, published in PNAS, shows that ice at minus 10 degrees Celsius releases more iron from common minerals than liquid water at 4 degrees Celsius. "Freezing creates microscopic pockets of liquid water between ice crystals. This means they can react with iron minerals even at temperatures as low as minus 30 degrees Celsius."