Acid rain can be carried great distances in the atmosphere, not just between countries but also from continent to continent. The acid can also take the form of snow, mists and dry dusts. The dry dust can cause respiratory illnesses in animals and humans such as asthma. 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.
In the 1970s the effects of acid rain were at their worst. 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 acid rain falls on a forest it trickles through the leaves of the trees and runs down into the soil below. Some of it finds its way into streams and then into rivers and lakes. Some types of soil can help to neutralise the acid - they have what is called a "buffering capacity". Other soils are already slightly acidic so these are particularly susceptible to the effects of acid rain.
Acid rain can effect trees in several different ways, it may:
dissolve and wash away the nutrients and minerals in the soilwhich help the trees to grow such as potassium, calcium and magnesium
cause the release of harmful substances such as aluminium into the soil and waterways which further affects wildlife.
wear away the waxy protective coating of leaves, damaging themand preventing them from being able to photosynthesise properly.
A combination of these effects weakens the trees which means that they can be easily attacked by diseases and insects or injured by bad weather. It is not just trees that are affected by acid rain, other plants may also suffer.
Lakes and rivers
It is in aquatic habitats that the effects of acid rain are most obvious. Acid rain runs off the land and ends up in streams, lakes and marshes - the rain also falls directly on these areas.
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.
Lakes, rivers and marshes each have their own fragile ecosystem with many different species of plants and animals all depending on each other to survive. If a species of fish disappears, the animals which feed on it will gradually disappear too. If the extinct fish used to feed on a particular species of large insect, that insect population will start to grow, which in turn will affect the smaller insects or plankton on which the larger insect feeds.
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.
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.