With winter weather upon us as we head further into December, the familiar sight of road de-icing trucks and snowplows are once again lining our streets and highways. We don’t think much of the materials that they’re using to make the roads safe enough to drive on, but a new study this month gives us pause to think about the environmental effects.
The University of Toledo published research this month about the deicer used on roads in most parts of the U.S.: regular table salt, or sodium chloride. Also used are other types of chlorides such as calcium and magnesium chloride. These road salts reduce the risk of car accidents by almost 80% so they are ubiquitously used; but when used in such large quantities, the run-off of this salt starts to affect local and global water sources.
Depending on the climate and amount of snowfall, salt applied to the roads can be as much as three to eighteen pounds of salt just in 1 square meter (about the size of a small table). When the ice melts and the wastewater is swept away, it travels to streams and even makes its way into private wells. The most concerning of these is the extreme salt concentration found in freshwater streams, up to 20-30x higher than the EPA recommends.
Researchers at the University of Toledo propose that the EPA thresholds need to be revised and cities need to take a different approach to managing ice on roads. These include storage facilities that contain the de-icing material within concrete, better snowplows that have more than one edged blade to cut down on the amount of deicing salt that’s required, and road care before and after anticipated storms.
With the freshwater ecosystem bearing the brunt of the de-icing solutions, the authors of this study are hoping to raise awareness about how we can make the roads safe enough for travel but also maintain the health of the land around us.
William D Hintz, Laura Fay, Rick A Relyea. Road salts, human safety, and the rising salinity of our fresh waters. Frontiers in Ecology and the Environment, 2021; DOI: 10.1002/fee.2433