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Salty
roads
In
an average year, North America's snowbelt uses 13 million
tons of salt to keep the traffic flowing, according to
the Environmental Protection Agency (EPA). The most commonly
used salt to deice the roads is sodium chloride, the same
as the table salt we use on our food. The salt effectively
depresses the freezing point of water and melts the ice
that has formed on the road.
The
salts, however, don't just stay on the roads. As cars
drive by, they splash the salty water on the vegetation
along the road. The salts also simply run off the road
into a ditch or at the side of the road, from where they
make their way into surface waters or percolate into the
groundwater.
The
increased concentrations of salt in the soil and the salt
splashed and sprayed onto branches and leaves damages
trees and vegetation along the road. The salt, for example,
inhibits water absorption, reduces root growth, and disrupts
the uptake of plant nutrients. A study by the Canadian
government, released in 2000, found that vegetation as
far as 162 feet (50 meters) away from the roadway was
damaged by the salts used on that road. The study also
found that plant species sensitive to salt were disappearing
along roadways.
Because
of the concerns for water supplies and ecosystems, government
agencies and scientists are looking at alternatives to
the use of road salts. An article about Environmental
Impacts of Road Salt and Alternatives in the New York
City Watershed
has more information about these alternatives.
References
and further reading
Related
Watershed Radio programs
- Search
for other Watershed Radio programs in the Archive.
About
the effects of road salt
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