Road salt is actually pretty terrible for the planet – are beets the solution?

truck salting road


Jamie Summers and Robin Valleau/The Conversation

Road salt saves lives but can harm aquatic wildlife. Marshes, streams and lakes lie alongside many of the roads and highways that zigzag across North America. Plants and animals inhabit these water bodies and can be exposed to many of the substances we put on those roads, including road salt.

Rock salt helps keep roads safe when winter storms hit, reducing winter road accidents. But it can also have serious, negative effects on aquatic ecosystems. At high concentrations, salt can be fatal to some aquatic animals. Salt can also change the way the water mixes and lead to the formation of salty pockets near the bottom of lakes, creating biological dead zones.

When the weather takes a wintry turn, many cities and municipalities in North America rely on salt to deice their roads. This rock salt is similar to table salt, made up of sodium and chloride, but coarser. It dissolves quickly on the road, leaving the chloride to enter nearby waters through runoff and leaching. In fact, almost all chloride ions from the road salt eventually find their way into waterways downstream.

At low concentrations, chloride is relatively benign. But as concentrations rise, it can be toxic to aquatic wildlife, including the plankton and fish that inhabit inland lakes. These ecological changes affect water quality.


IN SALT WATER 

One study of North American lakes found that as little as one per cent of the land area within 500 metres of the lake had to be paved (or otherwise impervious) for there to be an increased risk of becoming saltier over the longterm. Basically, a little development can lead to a lot of salt entering a water body. About 27 percent of large lakes in the United States are at least one percent developed along their shores…


 …Some communities in North America are looking for environmentally safe alternatives to road salt.

Beet wastewater—left over from sugar beet processing—cheese brine, pickle juice, and potato juice are some of the unconventional deicers being tested.

The carbohydrates or sugars in beet wastewater make it more effective at lower temperatures than salt water or brine alone, lowering the melting point of the ice to below -20℃ from -10℃—and reducing the amount of chloride applied to the road.

But there are downsides. Some communities dislike the smell of the beet wastewater, which people have likened to soy sauce, molasses, or stale coffee. It also adds sugar to aquatic ecosystems, which may encourage bacterial growth. Instead of using salt and salt additives, some engineers are experimenting with roads that clear themselves of snow and ice. Early tests have suggested that solar panels could replace asphalt to melt ice and eliminate the need for road salt, by heating water in pipes embedded in the road…

 

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