Rain water is naturally acidic (pH 6.5) because it contains dissolved carbon dioxide gas. This forms carbonic acid.The word equation is;
carbon dioxide + water = carbonic acid
When we burn fossil fuels (especially coal), sulphur dioxide is made and released into the air. When sulphur dioxide dissolves in rain water it makes sulphuric acid.
Sulphur dioxide + water = sulphuric acid
Sulphuric acid is much stronger than carbonic acid and causes damage to rocks, animals and plants.
When acid rain falls on to the soil, it is taken into plants and trees. This causes the plants to die as they can not live in acidic conditions. This can wipe out large areas of forest.
If it falls into lakes. It causes the acidity of the lakes water to increase. This causes fish and other animals to die.
Acid rain reacts with certain rocks, such as limestone. This causes them to wear away more quickly. Statues can lose their features and grave stones become very hard to read.
As this is a major problem, power stations have fitted scrubbers. These are giant towers that take the acidic gases and dissolve them into water. This makes acid which can then be neutralised by spraying the liquid with an alkali.
Photos from,
www.ivygreen.ctc.edu/lee-geog120/Chapters/chapter_3.htm
www.heptune.com/rain.html
www.hartwick.edu/envirsci/Issues/
acidrain/Acidrain.html
www.hd.ord/Damon/photos/natural-science/archive.HTM
