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Acid Rain

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Srinand Sundaram

on 28 September 2012

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Transcript of Acid Rain

Acid Rain Acid Rain is a broad term which refers to any precipitation which is unusually acidic.

This can be in the form of wet precipitation (rain, snow etc.) or as dry deposition, such as small soot or dust particles

This acidity is caused by an increased amount of acids in the rainwater, giving it a very low pH.

The presence of these acids is caused by pollutants which are released into the atmosphere, mainly sulphur dioxide and nitrogen oxides What is Acid Rain? How did they get there? SO 2 NO x Sulphur Dioxide Sulphur dioxide is produced mainly by the combustion of fossil fuels and production of electricity.
When these fuels are burnt in air, the sulphur is oxidised.
Sulphur dioxide can also be produced as part of industrial processes, such as the production of steel and the purification of some metal ores Having been released into the atmosphere, this sulphur dioxide undergoes various chemical reactions with moisture in the air to form sulphuric acid. Chemical reactions S+O SO 2 2 2SO + O 2SO 2 2 3 H O+SO H SO 2 2 3 4 Nitrogen oxides Nitrogen and oxygen do not usually react to form a nitrous oxide.

However, they do react at the very high temperatures caused by the combustion of fossil fuels in power stations, and also in vehicle engines.

Nitrogen reacts with oxygen to form nitric oxide, which is then oxidised further to produce nitrogen dioxide.

Both of these gases are acidic, and react with water in the atmosphere to produce nitrous and nitric acids. Both of these acids contribute to the production of acid rain Chemical reactions N +O 2NO 2 2 2NO+O 2NO 2 2 2NO +H O HNO +HNO 2 2 2 3 It's not all our fault... These gases are not just produced by human activity. There are some natural sources of sulphur dioxide and nitrogen oxides as well;
Sulphur dioxide is released by geothermal activity from beneath the Earth's crust

Nitrogen oxide is also produced by lightning strikes, which heat the air to a temperature at which nitrogen and oxygen can react with each other. ...but we are mainly responsible. The graphs below show the proportion of sulphur dioxide and nitrogen oxides released by human activity, and the proportion released from other sources A summary... ...of the production of acid rain What's the problem with acid rain? Forests Acid rain contributes to the mass destruction of trees in the following ways... The acid corrodes the leaves of the trees, reducing their ability to photosynthesise adequately.

It also dissolves away the nutrients and minerals which the trees of the forest rely on. These are then washed away by the rain.

In addition, the acidity in the precipitation also causes the release of other minerals into the soil, such as mercury and aluminium. These are toxic to the trees, and so cause significant damage.

The destruction of forests has knock-on effects on other organisms which live in that habitat, and so causes a reduction in the biodiversity of an area. Lakes, Rivers and Aquatic Ecosystems As acid rain falls on bodies of water, it increases their acidity. This has adverse effects on many marine organisms... At a pH of 5.0, small insects such as mayflies and snails are killed.

At this pH, most fish eggs cannot hatch. Many eggs can also become mutilated, from which deformed fry hatch. These small fish are soon killed by the acidity, while adult fish are killed as the pH becomes lower. This means that fish stocks begin to die out.

In addition, rain water from forests carrying toxic minerals reduces the fish populations further

As a result, larger predators such as reptiles and birds are affected. They too begin to die out as their prey becomes scarce. An acidified lake looks crystal clear. Although this may make it appear to be pleasant and appealing, it really shows that nothing can live in its waters as they are so acidic. Sadly this is the case with many lakes around the world Buildings and Structures Acid rain also affects many buildings and structures... Acid rain can corrode metals, causing significant damage to metal structures, such as steel skyscrapers and car bodies

Acids also react with carbonates (which form limestone and marble structures) and breaks them down. This is responsible for damage to many statues and monuments, as well as some builidings.

Acidic dry deposition (in the form of soot) also causes damage to and spoils some buildings. These soot particles stick to the buildings, changing their colour and appearance. What Can We Do? In order to prevent acid rain, a tangible way to start is by travelling less. As the earlier diagram showed, the majority of Nitrous oxide emissions come from transport. If cutting down on transport simply isn't practical, then taking public transport or carpooling can help Human Health Effects Despite the majority of the problems of acid rain arising due to wet deposition, this is not the case with humans. The health issues of acid rain are actually all caused by the dry deposition, which can aggravate and increase the likelihood of death by heart and lung disorders. These include Illnesses such as:
Permanent lung damage Who Gets Hurt? Some of the worst contributors to acid rain are some of the more industrial European countries, or the USA. But why is it that we often do not see the results here? Due to the prevailing winds that we get in Britain and the USA, the majority of our acid rain waste does not end up on our land. Instead, it travels miles through the air to eventually come to other countries - specifically Canada and Scandinavia As well as travelling less, conserving energy can also prevent acid rain. By doing simple things such as turning off lights, or leaving the heating off, if done on a large enough scale, will save a lot of energy, meaning less emissions will be made at power stations. In fact, anything that might even slightly help save energy can be helpful, as long as electricity is conserved. We Hope you enjoyed our presentation on Acid Rain Thank You for watching!
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