When fossil fuels such as coal, gasoline, and fuel oils are burned, they emitoxides of sulfur, carbon, and nitrogen into the air. These oxides combine withmoisture in the air to form sulfuric acid, carbonic acid, and nitric acid. Whenit 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 rainhave come to be recognized as a leading threat to the stability and quality ofthe Earth’s environment. Most of this acidity is produced in the industrializednations of the Northern Hemisphere–the United States, Canada, Japan, and mostof the countries of Eastern and Western Europe.
The effects of acid rain can be devastating to many forms of life, includinghuman life. Its effects can be most vividly seen, however, in lakes, rivers, andstreams and on vegetation. Acidity in water kills virtually all life forms. Bythe early 1990s tens of thousands of lakes had been destroyed by acid rain. Theproblem has been most severe in Norway, Sweden, and Canada.
The threat posed by acid rain is not limited by geographic boundaries, forprevailing winds carry the pollutants around the globe. For example, muchresearch supports the conclusion that pollution from coal-powered electricgenerating stations in the midwestern United States is the ultimate cause of thesevere 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 theColosseum in Rome, have shown signs of deterioration caused by acid rain. Scientists use what is called the pH factor to measure the acidity oralkalinity of liquid solutions. On a scale from 0 to 14, the number 0 representsthe highest level of acid and 14 the most basic or alkaline. A solution ofdistilled 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 consideredacidic. Rainfalls in the eastern United States and in Western Europe often rangefrom 4. 5 to 4. 0. Although the cost of such antipollution equipment as burners, filters, andchemical and washing devices is great, the cost in damage to the environment andhuman life is estimated to be much greater because the damage may beirreversible.
Although preventative measures are being taken, up to 500,000lakes in North America and more than 4 billion cubic feet (118 million cubicmeters) of timber in Europe may be destroyed before the end of the 20th century.Sebastian Kovacs emailprotectedCategory: Social Issues
