When
fossil fuels are burnt they release
sulphur dioxide and
nitrogen oxides. These mix with clouds and form
acids. These acids then fall as acid rain.
Acid rain causes lakes to become acidic, which has a severe effect on the ecosystem within that lake. The acid causes aluminium salts to dissolve in the water, and the resulting aluminium ions are poisonous to many fish and birds. Acid rain also kills trees and damages limestone buildings and stone statues.
Acid rain can be prevented by cleaning up emissions. Power stations now have "acid gas scrubbers" to take the harmful gases out before they release fumes into the atmosphere. Cars are now being fitted with catalytic converters to clean up exhaust gases.