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Acid Rain and its causes

Acid Rain - is the rainwater containing chemical pollutants that are release by burning fossil
fuels such as coal and oil. The two main pollutants are sulphur dioxide and nitrogen oxide
which are released in emissions from power stations, factories and car exhausts.

The effects of Acid Rain

 contamination of water supplies - harmful to human health
 cause chemical weathering of buildings e.g. Westminster Abbey
 crop yields reduced by increasing soil acidity
 increased acidity of freshwater lakes killing both fish and plant life - e.g. 18,000 lakes in
 Sweden badly poisoned - over 4000 have no fish left.
 important nutrients leached from the soil and replaced by aluminium which cause damage
 to plant and tree roots. Trees have become more susceptible to drought and disease. In
 1992 there were 3 million hectares of forest in Austria damaged by acid rain.
 annual cost of damage from acid rain in Europe is estimated to be between $0.5 and $3.5

Acid Rain: An International problem

The pollutants that cause acid rain are carried by wind (travelling 1000-2000km within the
atmosphere in 3-5days). They are therefore easily transported across international
boundaries. This means that a country suffering the effects of acid rain is not necessarily
responsible for its creation. Many forests and lakes in Scandinavia for example have been
damaged by pollution which has travelled from Britain. Therefore international co-operation
is essential to solve the problems caused by acid rain. Examples of these (from Flinders,
2001) include:-

1980s - joint study between UK electricity generators /coal producers and Norway and
Sweden to research the processes resulting in acid rain.

UN proposal signed / agreed by a few countries (not the UK) achieved a 30% reduction in
sulphur dioxide emissions.

Attempts to reduce the effects of Acid Rain - cure or prevention?

Adding lime to polluted can help to reduce the pH of the water, reducing acidity e.g. used in
Sweden. In Germany trees have been sprayed to wash off the acid. BUT these cures are not
long-term solutions and they are expensive.

Prevention is obviously the ideal solution, however to achieve this sulphur dioxide and
nitrogen oxide emissions must be reduced, examples of how this can be achieved include:

 Burning non-fossil fuels (i.e. nuclear or renewable fuels)
 Burning low-sulphur coal (can reduce sulphur emissions by up to 15%)
Producing energy-efficient car engines
Fitting power stations with filters and low temperature burners (this is however
expensive and to this nation wide, the costs may run into billions.
'Scrubbers' - equipment used to remove up to to 90% of sulphur dioxide emissions in coal-
burning plants (but very expensive)
Using lead-free petrol - major factor in reducing exhaust emissions in the UK.

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