In the wake of a bomb cyclone that hit the Northeast U.S. in early January, many cities have sent out teams to dump fresh layers of ice-melting salt onto streets and sidewalks. But a new study shows just how those kinds of coatings might be hurting the country's waterways and ecosystems. (Related: "Bomb Cyclones and Polar Vortexes—This Winter's Scary Weather Explained")

In a first-of-its-kind study, published January 8 in the Proceedings of the National Academy of Sciences, researchers looked at chemical changes in freshwater across the United States and southern Canada. The study investigated 232 monitoring sites throughout the last half-century and found that our waterways are getting saltier and more alkaline, which could lead to dangerous effects.