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What is acid rain?
Acid rain is a result of air pollution. 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 don't just contain the sooty grey particles that you can see - they also contains lots of invisible gases that can be even more harmful to our environment.
Acid rain was considered a major problem in the 1980s and while steps to reduce sulphur emissions have been succesful we are still feeling the effects today, and there is still work to be done.
Air pollution was once seen as a local issue but it was in southern Scandinavia in the late 1950's that the problems of acid rain were first observed, and it was then that people began to realise that the origins of this pollution were far away in Britain and Northern Europe. One early answer to industrial air pollution was to build very tall chimneys. Unfortunately all this does is push the polluting gases up into the clouds allowing emissions to float away on the wind. The wind carries the pollution many hundreds of miles away where it eventually falls as acid rain. In this way Britain has contributed at least 16% of the acid rain that has fallen in Norway. In fact over ninety percent of Norway's acid pollution comes from countries other than itself. In 1994 Germany, UK, Poland and Spain produced over a million tons of sulphur emissions each. Governments have since admitted that acid rain is a serious environmental problem and many countries have taken steps to reduce the amount of sulphur and nitrogen emissions, but they are still a problem.
Ships are major contributors to sulphur emissions as the sulphur content of their heavy fuel oil is very high (5% compared to the EU maximum allowed in car fuels of 0.001%). The shipping industry is taking steps to reduce emissions as estimates predict that if nothing is done soon then the sulphur emissions of the industry would exceed all those from land-based sources by 2020.
Acidity is measured using a scale called the pH scale. This scale goes from 0 to 14. 0 is the most acidic and 14 is the most alkaline (opposite of acidic). Something with a pH value of 7, we call neutral, this means that it is neither acidic nor alkaline.
Forests all over the world were dying and in Scandinavia the fish were dying; lakes looked crystal clear but contained no living creatures or plant life. Many of Britain's freshwater fish were threatened; their eggs were damaged and deformed fish were hatched. This in turn affected fish-eating birds and animals. Animals belong to a food chain and often if one link in a food chain is taken away it can have devastating effects.
It is thought that acid rain causes trees to grow slower or even to die but scientists have found that the same amount of acid rain seems to have more effect in some areas than it does in others.
As the acidity of a lake increases, the water becomes clearer and the numbers of fish and other water animals decline. Some species of plant and animal are better able to survive in acidic water than others. Freshwater shrimps, snails, mussels are the most quickly affected by acidification followed by fish such as minnows, salmon and roach. The roe and fry (eggs and young) of the fish are the worst affected as the acidity of the water can prevent eggs from hatching properly, can cause deformity in young fish which also struggle to take in oxygen.
The acidity of the water does not just affect species directly, it also causes toxic substances such as aluminium to be released into the water from the soil, harming fish and other aquatic animals.
Every type of material will become eroded sooner or later by the effects of the climate. Water, wind, ice and snow all help in the erosion process but unfortunately, acid rain can help to make this natural process even quicker. Statues, buildings, vehicles, pipes and cables can all suffer. The worst affected are things made from limestone or sandstone as these types of rock are particularly susceptible and can be affected by air pollution in gaseous form as well as by acid rain.
What has been done?
Introduced across Europe on 1 January 2008, the Large Combustion Plant Directive (LCPD) aims at reducing sulphur emissions by giving coal fired plants two options. They can either agree to a very limited running programme and close down by 2015, or install the equipment needed to remove sulphur from plant emissions.
The 1999 Gothenburg Protocol set limits on emissions and came into force in 2010. Unfortunately international agreements failed to include shipping which uses sulphur rich fuels that are now banned on land, so emissions from the North sea could still reach countries such as Norway. However, in July 2011 the European Commission proposed to reduce sulphur emissions from the fast-growing maritime and shipping industry by 90% by limiting the legal sulphur content allowed in fuels in certain areas such as the Channel and Baltic Sea.
Whilst many countries have reduced their emissions, an upsurge in industrialisation and reliance on fossil fuels in countries such as China could lead to a further increase in sulphur dioxide emissions.
What about nitrogen?
Restoring the damage
• 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.
• Governments 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.
Find alternative sources of energy• Governments need to invest in researching different ways to produce energy.
• Two other sources that are currently used are hydroelectric and nuclear power. These are 'clean' as far as acid rain goes but what other impact do they have on our environment?
• Other sources could be solar energy or windmills but how reliable would these be in places where it is not very windy or sunny?
• All energy sources have different benefits and costs and all theses have to be weighed up before any government decides which of them it is going to use.
• Greater subsidies of public transport by the government to encourage people to use public transport rather than always travelling by car.
• Every individual can make an effort to save energy by switching off lights when they are not being used and using energy-saving appliances - when less electricity is being used, pollution from power plants decreases.
• Walking, cycling and sharing cars all reduce the pollution from vehicles.
For further information on acid rain and what you can do about it visit:
Act On CO2
Campaign for Better Transport
Last updated: November 2011 EB