Acid rain Cambridge IGCSE Environmental Management revision
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In plain words
Rain has always been a little acidic. In the last century it became acidic enough, downwind of power stations, to empty lakes of fish and eat the faces off statues. The cause was two gases, and both can be caught before they leave the chimney or the exhaust pipe.
10 things to know
- Sulfur dioxide is released by the combustion of fossil fuels that contain sulfur compounds. It is also released in volcanic gases.
- Oxides of nitrogen form when nitrogen from the air reacts with oxygen at the high temperature inside vehicle engines.
- Sulfur dioxide and oxides of nitrogen react with oxygen and water vapour in the atmosphere to form acid rain.
- The gases can be carried a long way by the wind, so acid rain often falls far from where the pollution was made, even in another country.
- Impacts on water: lakes and rivers become acidic. Fish populations fall, and that affects the whole aquatic food web.
- Impacts on land: soils become acidic. Crops and other vegetation are damaged. Plants lose their leaves, which is called defoliation, and crop yields fall.
- Buildings are damaged, especially those made of limestone and marble, which react with acid.
- Flue-gas desulfurisation removes sulfur dioxide from the waste gases of a power station by reacting it with calcium carbonate or calcium oxide.
- Catalytic converters, fitted to vehicle exhausts, remove oxides of nitrogen. Transport policies reduce the number of vehicles and the fuel burned.
- Limitations. Desulfurisation equipment and catalytic converters add cost. Converters do nothing about carbon dioxide. Because the gases cross borders, countries have to cooperate.
Worked example
A lake has lost its fish, although no factory or farm drains into it. A coal-fired power station stands 200 km upwind. Explain the link.
- Burning coal releases sulfur dioxide, because coal contains sulfur compounds.
- The wind carries the gas towards the lake. It reacts with oxygen and water vapour in the air to form acid rain.
- The acid rain falls on the lake and makes it acidic, so the fish die or cannot breed.
Tips and tricks
- Two gases, two sources. Sulfur dioxide comes from sulfur in the fuel. Oxides of nitrogen come from nitrogen in the air, in hot engines.
- Carbon dioxide is not the cause of acid rain. Leave it out of an acid rain answer.
It lands in your notebook with its questions as flashcards.
Acid rain: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Which two gases cause acid rain?
They react with oxygen and water vapour to form acids.
What is a natural source of sulfur dioxide?
Volcanic gases contain sulfur dioxide.
What does flue-gas desulfurisation remove?
It reacts the gas with calcium carbonate or calcium oxide.
What does a catalytic converter remove?
It is fitted to the exhaust of a vehicle.
What is defoliation?
A plant without leaves cannot photosynthesise.
Why can acid rain damage a lake in a country with very little industry?Stretch
The pollution is made in one place and falls in another.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 8 marks. Write your answers on paper, then check them.
Acid rain
Cambridge IGCSE Environmental Management 0680 · 8 marks · papermunch.org
Name ______________________________ Date ______________
Describe how acid rain forms.[3]
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Sulfur dioxide and oxides of nitrogen are released into the atmosphere. They react with oxygen and water vapour. The acids formed fall as acid rain.
Explain how oxides of nitrogen are formed in a vehicle engine.[2]
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The temperature in the engine is very high. Nitrogen from the air reacts with oxygen to form oxides of nitrogen.
Describe three impacts of acid rain.[3]
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Any three: lakes and rivers become acidic; fish populations fall and aquatic food webs are affected; soils become acidic; crops and vegetation are damaged, with defoliation and lower yields; buildings are damaged.
Answers: Acid rain
- 1. Sulfur dioxide and oxides of nitrogen are released into the atmosphere. They react with oxygen and water vapour. The acids formed fall as acid rain.
- 2. The temperature in the engine is very high. Nitrogen from the air reacts with oxygen to form oxides of nitrogen.
- 3. Any three: lakes and rivers become acidic; fish populations fall and aquatic food webs are affected; soils become acidic; crops and vegetation are damaged, with defoliation and lower yields; buildings are damaged.