Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals are produced.

Restoring the damage

Lakes and rivers can have powdered limestone added to them to neutralise the pH of the water - this is called "liming". Liming, however, is expensive and its effects are only temporary - it needs to be continued until acid rain stops. The people of Norway and Sweden have successfully used liming to help restore lakes and streams in their countries.

A major liming programme took place in Wales where 12,000 km of its waterways were acidified.  In 2003 liming of the river Wye led to a return of the salmon which had completely disappeared in 1985.  However, other parts have taken longer to recover and there are still no signs of life.

Recently a more positive side of acid rain has been noted as it can be very effective at reducing the natural production of methane, a “greenhouse gas” approximately 23 times more powerful than carbon dioxide, especially in wetland areas.  The sulphur in acid rain limits the activity of methane-producing microbes found in wetland areas. (New Scientist)

Read More: What can we do to help?

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