Acid Rain

Acid rain forms when sulfur and nitrogen dioxides combine with moisture
in the atmosphere to produce rain, snow, or another kind of precipitation. This
kind of pollution may also be suspended in fog or deposited in a dry form. Acid
rain is most common in North America and Europe. Acid rain has also been
detected in other areas of the world such as tropical rain forests of Africa.
Canada has placed limitations on the sulfur emissions. The United States has
not, so the emissions may still drift into Canada.
The acid rain cycle begins with hundreds of power plants burning
millions of tons of coal. Burning coal produces electricity for us. Coal is
made of carbon, but the coal that we mine is not pure carbon. It is mixed with
other minerals. Two of these are sulfur and nitrogen. Then the coal is burned
some of the sulfur changes into sulfur dioxide and nitrogen changes into
nitrogen oxide. These escape in to the air as poisonous gases. Some smokestacks
release chemicals like mercury, arsenic, and aluminum. Some of these minerals
are changed in to gases and others become tiny specks of ash. As these
chemicals drift, they may change again. They may react with other chemicals in
the air. When sulfur dioxide combines with water, the result is sulfuric acid.
When nitrogen oxide gas combines with water, the result is also another acid.
When the clouds releases rain or other precipitation, the acid goes with it.
This is called acid rain.
The level of acid is measured in pH levels. The pH scale begins at 0
and ends with 14. A reading lower than 7 is called acidic, and a reading higher
than 7 is called basic. Seven is neutral. Normal rain is slightly acidic with a
pH level of about 6.5. Rain with a pH of 5.5 is then times more acidic than
normal rain and rain with pH of 4.5 is a hundred times more acidic than normal
rain. In parts of the country, rain with pH levels of 4.5 to 5.0 is common.
An English scientist named Robert Angus Smith discovered acid rain in
1872, but no other scientist continued this study. Then in 1961 the Sweden
wanted to know why the fish in their lakes were dying. Svante Odén discovered
that the reason was acid rain. After Odén's discovery, other scientist began to
study acid rain too.
Acid rain has destroyed plant and animal life in lakes, damaged forests
and crops. It has also endangered marine life in coastal waters, eroded
structures, and contaminated drinking water. It can kill fish, frogs, and
insects in lakes. Acid rain can also be harmful to humans. It can hurt their
lungs and make it harder for them to breath. Acid fog can be particularly
harmful to people with respiratory problems. Acid rain can corrode stones and
some metals. Higher acid levels can be dangerous to our drinking water. Some
water pipes are made of lead, and when the water is acidic, it can dissolve the
metal. Then the metals end up in the water we drink.