Acid Rain

When any type of fuel is burnt, lots of different chemicals are produced. The smoke that comes from a fire or the fumes that come out of a car exhaust contains lots of gases that can be harmful to our environment.

Power stations, factories and cars all burn fossil fuels and therefore they all produce polluting gases. Some of these gases (especially nitrogen oxides and sulphur dioxide) react with the tiny droplets of water in clouds to form sulphuric and nitric acids.

The release of sulphur dioxide can also occur naturally when a volcano erupts.

Acid rain is a very weak acid, it usually has a pH of 4.  Normal rain water is less acid with a pH of 5 or 6.

Sulphur dioxide mixes with water to form sulphuric acid.

Nitrous oxides mixes with water to form nitric acid

Carbon dioxide mixes with water to form carbonic acid.  

Effects of Acid Rain

Acid rain can be carried great distances in the atmosphere. The acid can also take the form of snow, mists and dry dusts.

The rain sometimes falls many miles from the source of pollution but wherever it falls it can have a serious effect on soil, trees, buildings and water. 

- Erodes buildings and statues (limestone and marble)
- Takes away valuable minerals in the soil (bad for agriculture)

- Acid rain cause calcium to be leached from the needles of red spruce, these trees become less cold tolerant and exhibit winter injury and even death.

- Increases toxic materials taken up by plant roots (root damage, stunted growth)
- Lowered pH of lakes, rivers and streams is toxic to fish and other aquatic species

-Loss of aquatic species in lakes results in a break in the food chain

-Breathing and lung problems in children and adults who have asthma and in children have been linked to acid air pollution. Everything that we eat, drink, and breathe has at one time come in contact with acid deposits.

What can be done to reduce acid rain?

  1. Reduce emissions:
    • Burning fossil fuels is still one of the cheapest ways to produce electricity so people are now researching new ways to burn fuel which don't produce so much pollution.
    •Energy producers need to spend more money on pollution control even if it does mean an increase in the price of electricity.
    • Sulphur can also be 'washed' out of smoke by spraying a mixture of water and powdered limestone into the smokestack.
    • Cars are now fitted with catalytic converters which remove three dangerous chemicals from exhaust gases. 

  2. Find alternative sources of energy
    • Renewable sources on energy are some of the cleanest ways to produce energy.  Solar farms, wind farms, hydroelectric dams and nuclear power plants release almost no harmful pollutants 

  3. Conserving resources
    • Use public transport rather than always travelling by car.
    • Save energy by switching off lights when they are not being used and using energy-saving appliances - when less electricity is being used, and therefore pollution from power plants decreases.
    • Walking, cycling and sharing cars all reduce the pollution from vehicles.

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All images sourced from unless otherwise stated