ACID RAIN

Pure water is neutral with a pH of 7.
Pure rain has a pH of 5.6, due to the carbon dioxide naturally present within the atmosphere. This CO2 interacts with water to form carbonic acid in water.
Automobile battery acid has a pH of 1.
Vinegar has a pH of 3.
Acid rain has pH of 1.5 to 5.6.
On average Sydney rain has a pH of 4.3.
Sulfur dioxide and Nitrous oxide are sources of acid rain.

Sulfur dioxide is dominantly from power plants which burn coal.
Nitrous oxides from cars, trucks and power plants (called NOx).
Taller emission stacks have spread problems. To reduce local pollution companines installed taller chimneys or stacks. This results in polluting a larger region down wind..
Main source of acid rain is sulfur dioxide and nitrogen oxides in the atmosphere.

If the bedrock consists of limestone, effect is not so severe. The limestone helps to neutralize the acid.
If bedrock is granitic, there is no buffer. Results severe.
Acid solutions free nutrients as well as toxic metals from the soil. As a result, nutrients are lost from the soils and the plants may take on toxic elements.
In lakes, acidity keeps the nutrients in solution. Nutrient are then lost with the outflow of water. Algae cannot grow as a result, and so there is no food for aquatic animals present in the lake.
Fish may be poisoned by heavy metals in solution, and are very intolerant of high acidity.
High acidity kills trees.

Tree ring studies have shown that concentrations of calcium (which is an essential nutrient for trees) have been decreasing steadily in areas of increased acid rain.

General Guide and links by Center for International Earth Science Information Network http://www.ciesin.org/TG/OZ/oz-home.html
National Oceaninc and Atmospheric Administration's Climate Monitoring and Diagnostic Laboratory: http://www.cmdl.noaa.gov/
The Environmental Protection Agency ozone page: http://www.epa.gov/ozone/

The Environmental Protection Agency acid rain page: http://www.epa.gov/docs/acidrain/
A good general guide to acid rain and acid rain resoures online: http://qlink.queensu.ca/~4lrm4/