Acid rain is a form of air pollution caused by the release of sulfur dioxide from the burning of fossil fuels. Explain how the burning of fossil fuels contributes to air pollution and describe two harmful effects that acid rain can have on ecosystems.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Fossil fuels such as coal and oil are burned in power stations and vehicles, releasing pollutant gases into the atmosphere. One of these pollutants, sulfur dioxide, dissolves in water vapour in the atmosphere to form acid rain.
Model answer (4 marks)
Burning fossil fuels releases sulphur dioxide (SO₂) into the atmosphere, which reacts with water vapour to form sulphuric acid – a key component of acid rain. The SO₂ also contributes to the formation of fine particulate matter and other pollutants, worsening air quality.
Acid rain lowers the pH of soils, reducing fertility and inhibiting plant growth. It also acidifies lakes and rivers, killing fish and other aquatic organisms. The loss of these organisms disrupts food chains and reduces biodiversity.
Acid rain lowers the pH of soils, reducing fertility and inhibiting plant growth. It also acidifies lakes and rivers, killing fish and other aquatic organisms. The loss of these organisms disrupts food chains and reduces biodiversity.
Examiner tips
- Use the term "sulphur dioxide" and mention its reaction to form acid rain; link to air pollution. Show two distinct effects: soil fertility and aquatic life. Mention disruption of food chains or biodiversity to hit all points.
Common mistakes
- Confusing sulphur dioxide with carbon dioxide; not specifying the acid rain mechanism. Listing only one harmful effect or combining soil and water effects into one point.
Mark scheme (4 marks)
- Burning fossil fuels releases sulfur dioxide (and/or carbon dioxide) into the atmosphere, causing air pollution
- Acid rain lowers the pH of soil, making it less fertile / preventing plant growth
- Acid rain lowers the pH of lakes and rivers, killing aquatic organisms
- Loss of organisms from affected habitats disrupts food chains / reduces biodiversity
Key terms in this question
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Pollution questions
- Untreated sewage is sometimes discharged into rivers. Explain how the discharge …
- Insecticides used in farming can enter nearby rivers and accumulate in the bodie…
- Non-biodegradable plastic is a major source of pollution in both land and water …
- Describe the process of eutrophication, including how it leads to a reduction in…