Road salt and the environment Essay

This essay has a total of 1489 words and 7 pages.

road salt and the environment

As awareness for pollution increases, other less noticed types of pollution are
recognized. Almost 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
•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 concentrations in the water are
average around 10 environmental Concentrations found in ground water near major highways
have been recorded as high as 250 mg/litre which is around the threshold of taste.

The main factor with ground water pollution is the risk to human health. The raised level
in sodium in water can cause high blood pressure and hypertension. With people who already
suffer from these problem it is necessary to keep their salt intake relatively low, they
should not drink water above 20 mg/liter. Although this is recommended, a study of private
well water in Toronto showed that half the wells exceeded this limit, twenty percent
exceeded 100 mg/litre and six percent exceeded 250 environmental This increase in sodium
and chlorine can also cause problem with water balance in the human body.

As well as surface water, ground water is also affected by road salting. Although the
effects are not as great as ground water, they still pose problems to the environment. The
problems are based on the salt ions. The salt ions interact with heavy metal that fall to
the bottom of the body of water. An example of this is when sodium and chlorine ions
compete for mercury to bond with. This cause the release of mercury into the water system.
The risk of mercury poisoning is far greater than that of sodium or chlorine. This
increase of sodium and chlorine as well as mercury and other heavy metal also cause
changes in the pH of water.

The increase of salt around bodies of water also effect aquatic life in the area. Two main
areas that are effected are osmotic regulation in fish and the death of micro-biotic life
in ponds and lakes. Most fish life can only tolerate a narrow range of salt content in the
water. The increase of salt in the water produced by road deicing cause freshwater fish to
swell up with water. The increased salt cause a lower concentration of water in the fishes
cells. To compensate, the fishes body takes in water to restore equilibrium. This can kill
fish if the salt concentration becomes to high.

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