Road salt may keep streets and sidewalks ice-free, but not without consequence.

The heavy use of road salt in the winter poses threats to the environment, said Lauren Kinsman-Costello, an assistant professor in the department of biological sciences.

Roads and sidewalks are impervious to water, meaning they do not allow water to infiltrate their surfaces. When people dump salt on icy roads, the ice melts and the salt dissolves into it, Kinsman-Costello said.

“When rain falls on those surfaces or when snow melts, that salt dissolves into that liquid, and then wherever that liquid goes is where the salt ends up,” Kinsman-Costello said.

After the liquid runs off the road, it can end up in a variety of places, such as nearby streams, soils and wetlands. This creates problems for plants and organisms, Kinsman-Costello said.

When road salt ends up in soil, it can negatively affect groundwater and plant growth in the area, said Anne Jefferson, an associate professor in the department of geology.

Road salt is made up of sodium chloride. When it enters soil, the chloride moves with the liquid and eventually reaches streams or groundwater while the sodium sticks to the soil particles and disrupts plant growth, Jefferson said.

In addition, road salt can be harmful to an area’s native organisms, Jefferson said.

“When a lot of road salt is getting into the aquatic ecosystems,” Jefferson said, “the health of those plants and animals and organisms can suffer, and they might not be as successful at growing or reproducing.”

Organisms that live along streams and wetlands in Ohio rely on freshwater for survival. When road salt enters these freshwater ecosystems, it makes it difficult for the native species to continue living. At the same time, species from other areas that thrive in saltwater environments can invade the ecosystem, Jefferson said.   

 “Eventually, we might see a loss of our native plant and animal communities and replacement with invasive species,” Jefferson said.

The problems caused by road salt have gotten worse in recent years, said Kuldeep Chaudhary, an assistant professor in the department of geology. According to a report published by the Cary Institute of Ecosystem Studies, the U.S. uses between 10 and 20 million tons of road salt each year.

“The concentration of salt as discharged as a baseflow to the streams has constantly increased for the last four or five decades,” Chaudhary said.

Alternatives to road salt exist, but they are not widely used because they are typically more expensive, Chaudhary said.  

One way to reduce the negative effects of road salt would be to instead use a salt brine, Jefferson said.

Rather than pour salt on the roads after a snowstorm, maintenance crews can apply a salt brine to them prior to it, Jefferson said. Although they would still be using salt, they would be “using a lot less of it.”

Road salt can also be substituted with agricultural products, such as pickle juice and sugar beets, Jefferson said. These products would normally be considered waste, so this would be a way to recycle them.

Paige Bennett is the Sciences reporter. Contact her at [email protected].