Road Salt Changes Urban Ecosystems

Jason G. Goldman, reporting for Conservation This Week:



In the urban parts of Minneapolis and St. Paul, Minnesota, around three hundred thousand tons of salt are dumped onto roads each winter. That’s because sodium chloride lowers the freezing point of water, making the formation of ice on the surface of roadways less likely. It keeps drivers safer, since car tires can hold onto imperfect road surfaces better than they can grip slippery, wet ice.

But dumping all that salt into the ecosystem doesn’t just keep drivers safer. It also changes the chemical composition of the soil near roadways, and that added sodium chloride finds its way into plants, into bodies of water, and into animals. And all that added salt could shift the dynamics of natural selection and the animals’ fitness, altering the course of evolution. That’s how natural selection works – it’s neither good or bad – but it’s worth at least being aware of the sometimes nuanced effects that human behavior have on natural ecosystems.

Mudhole? Slimy? Salty? My home this is!