Question

Acid Rain


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.

Power stations, factories and cars all burn fuels and therefore they all produce polluting gases. Some of these gases (especially nitrogen oxides and sulphur dioxide) react with the tiny droplets of water in clouds to form sulphuric and nitric acids. The rain from these clouds then falls as very weak acid - which is why it is known as "acid rain".


How acidic is acid rain?

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.

Very strong acids will burn if they touch your skin and can even destroy metals. Acid rain is much, much weaker than this, never acidic enough to burn your skin.

Rain is always slightly acidic because it mixes with naturally occurring oxides in the air. Unpolluted rain would have a pH value of between 5 and 6. When the air becomes more polluted with nitrogen oxides and sulphur dioxide the acidity can increase to a pH value of 4. Some rain has even been recorded as being pH2.

Vinegar has a pH value of 2.2 and lemon juice has a value of pH2.3. Even the strongest recorded acid rain is only about as acidic as lemon juice or vinegar and we know that these don't harm us - so why do we worry about acid rain?


The Effects of Acid Rain

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 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.

Forests all over the world are dying, fish are dying. In Scandinavia there are dead lakes, which are crystal clear and contain no living creatures or plant life. Many of Britain's freshwater fish are threatened, there have been reports of deformed fish being hatched. This leads to fish-eating birds and animals being affected also. Is acid rain responsible for all this? Scientists have been doing a lot of research into how acid rain affects the environment.



Forests

It is thought that acid rain can cause trees to grow more slowly or even to die but scientists have found that it is not the only cause. 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 on 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 and 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 soil
which help the trees to grow.

• cause the release of harmful substances such as aluminium into the soil.

• wear away the waxy protective coating of leaves, damaging them
and preventing them from being able to photosynthesise properly.

A combination of these effects weakens the trees which means that they can be more 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.

Answer 1

Answer:

Acid rain is the first rain of the rainy season. It includes all the dust of cloud. There is dust, smoke and harmful chemicals.

Answer 2

Acid rain is precipitation containing large quantities of impurities leading to a shift in the pH of the water to less than seven.

• The rain produced due to these impurities usually has a pH of less than 5.2, making it harmful to living organisms, shelters, and buildings
• The impurities primarily consist of sulphur and nitrogen gases, namely sulphur dioxide ( SO₂) and nitrogen oxides ( NO and NO₂)
• These gases are primarily released due to the effects of air pollution. This is a result of human interference, development and industrialization has paved the way for a rapid change in our immediate and distant surroundings. Transportation, factories, and unsustainable waste management practices cause the release of sulphur and nitrogen-containing pollutants into the air. These particles remain suspended in the atmosphere, clinging to surrounding moisture
• The rain produced when condensation of the air occurs causes the pollutants to get mixed with the water droplets, leading to the formation of acid rain
• Acid rain causes damage to property. A famous example is the damage to our national monument, The Taj Mahal. Acid rain had led to the yellowing of the white marble slabs; restoring the memorial to its past glory required immense work
• Acid rain also leads to a variety of dermatological and respiratory conditions. Rashes, skin lesions can occur, and it can also aggravate conditions such as asthma

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