Acid Rain 2

ACID RAIN. When fossil fuels such as coal, gasoline, and fuel oils are
burned, they emit oxides of sulfur, carbon, and nitrogen into the air.
These oxides combine with moisture in the air to form sulfuric acid,
carbonic acid, and nitric acid. When it rains or snows, these acids are
brought to Earth in what is called acid rain.
During the course of the 20th century, the acidity of the air and acid
rain have come to be recognized as a leading threat to the stability and
quality of the Earth's environment. Most of this acidity is produced in the
industrialized nations of the Northern Hemisphere--the United States, Canada,
Japan, and most of the countries of Eastern and Western Europe.
The effects of acid rain can be devastating to many forms of life,
including human life. Its effects can be most vividly seen, however, in
lakes, rivers, and streams and on vegetation. Acidity in water kills
virtually all life forms. By the early 1990s tens of thousands of lakes had
been destroyed by acid rain. The problem has been most severe in Norway,
Sweden, and Canada.
The threat posed by acid rain is not limited by geographic boundaries, for
prevailing winds carry the pollutants around the globe. For example, much
research supports the conclusion that pollution from coal-powered electric
generating stations in the midwestern United States is the ultimate cause of
the severe acid-rain problem in eastern Canada and the northeastern United
States. Nor are the destructive effects of acid rain limited to the natural
environment. Structures made of stone, metal, and cement have also been
damaged or destroyed. Some of the world's great monuments, including the
cathedrals of Europe and the Colosseum in Rome, have shown signs of
deterioration caused by acid rain.
Scientists use what is called the pH factor to measure the acidity or
alkalinity of liquid solutions. On a scale from 0 to
14, the number 0 represents the highest level of acid and 14 the most basic
or alkaline. A solution of distilled water containing neither acids nor
alkalies, or bases, is designated 7, or neutral. If the pH level of rain
falls below 5.5, the rain is considered acidic. Rainfalls in the eastern
United States and in Western Europe often range from 4.5 to 4.0.
Although the cost of such antipollution equipment as burners, filters, and
chemical and washing devices is great, the cost in damage to the environment
and human life is estimated to be much greater because the damage may be
irreversible. Although preventative measures are being taken, up to 500,000
lakes in North America and more than 4 billion cubic feet (118 million cubic
meters) of timber in Europe may be destroyed before the end of the 20th
century.


Sebastian Kovacs Copyright@1997