Learning Objectives
- Understand what is meant by acid deposition and what causes it
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Understand some of the problems associated with acid deposition
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Understand the difference between pre- and post- combustion methods of reducing sulfur dioxide emissions
Acid Deposition
Acid deposition is a more general term than acid rain. It refers to any process in which acidic substances (particles, gases and precipitation) leave the atmosphere to be deposited on the surface of the Earth. It can be divided into wet deposition (acid rain, fog and snow) and dry deposition (acidic gases and particles).
Causes of Acid Rain
Acid rain results when sulfur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents
The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids, mixing with water and other materials before falling to the ground.
The major sources of sulfur dioxide (SO2) and nitrogen oxides (NOX) are
- Burning fossil fuel in generating electricity
- Mobile vehicle
- Manufacturing, oil refineries and other industries.
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