Chapter 28: Air Pollution

28.1.1.1 Acidification

Carbon dioxide, sulphur dioxide and nitrogen oxides are all emitted in large quantities through the combustion of fossil fuels. This has been most marked in the northern countries but industrialization is now advancing in the southern hemisphere.

Direct fallout of acid pollutants takes place as dry deposition. When these pollutants dissolve in atmospheric moisture to form acids, they fall in precipitation as wet deposition. This form of pollution may be transported over long distances and it therefore constitutes an international issue. For example a substantial percentage of acid deposition in Scandinavia originates in the United Kingdom. Various forms of environmental damage are caused:

• Fresh waters become acidified to an extent dependent on the capacity of the local geology to neutralize acids. At a pH of 5, fish begin to disappear and when pH falls to 4.5, virtually all aquatic life is eliminated. Acid rain also releases toxic metals from the environment into lake water. These harmful effects impact on dependent food chains. The effect has accumulated over a period of...