Salt Pollution
...everyone knows about toxic waste and carbon dioxide pollution,
but not many people have heard of salt pollution. Salt pollution has been on
the increase since the evolution of the automobile. With more pressure on
government agencies to keep the highway clear and safe, an increase in the use
of salt has developed. It is important to understand why salt is used and how
it work as well as the environmental effects to understand the salt pollution
problem.
Salt is a necessary and accepted part of the winter environment. It
provides safety and mobility for motorists, commercial vehicles and emergency
vehicles. Salt is used as the principal deicer because it is the most available
and cost-effective deicer. Rock salt is preferred because it is cheap and
effective. It costs 20 dollars a ton where as an alternative like calcium
magnesium cost around 700 dollars a ton. Some 10 million tons of deicing salt is
used each year in the U.S. and about 3 million in Canada.
Salt is used to keep snow and ice from bonding to the pavement and to
allow snowplows to remove. When salt is applied to ice and snow it creates a
brine that has a lower freezing temperature than the surrounding ice or snow.
Salt is the ideal deicing material because it is:
the least expensive deicer
easy to spread
easy to store and handle
readily available
non-toxic
harmless to skin and clothing
Salt pollution is broken into two main groups. Water, which includes
the effects on ground water, surface water and aquatic life and land.
Most of the salt applied to the roadways eventually ends up in the
ground water. It is estimated that 30% to 50% of the salt used travels into the
ground water. Salt effect two areas of ground water, chloride concentration and
sodium concentration. Chlorides may be present in the form of sodium chloride
crystals or as a ion in a solution. Normal...
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