The 'Wide-Ranging Ecological Downside' of Road Salt
According to a study published in Proceedings of the National Academy of Sciences, as reported by Don Hopey, “sodium chloride’s use to melt snow and ice also has a big, long-term and wide-ranging ecological downside.”
The unintended consequences of road salt are not breaking news (In Canada, it’s a regulated toxin), and this is the second study on the topic published in PNAS in the last year. But this is the first to "assess the extended changes in freshwater salinity and alkalinity across the continent."
The study also touches on the effects of fertilizer and runoff from mining operations, both of which are contribute significantly to the study’s findings in the agricultural areas of the Midwest.
In the cities, however, salt remains the primary culprit. Hopey writes:
“Waterway contamination from road salt is particularly bad in urban areas, and because it’s transported more easily than sodium, chloride is the greater concern, according to the USGS. An estimated 40 percent of the nation’s urban streams have chloride levels that endanger their aquatic life, largely because of road salt.”
Strategies to mitigate the effects of road salt include pre-salting and beet juice (but likely not sand) as well as technological advances Hopey details after speaking with an official from the Pennsylvania Department of Transportation.
But regardless of what happens in the future, planners will have to grapple with the fact that "many of the nation’s major rivers and river systems, including the Hudson, Potomac, Canadian, Chattahoochee and Mississippi" have endured "significant changes" to their ecology over the last five decades.