Study Notes
Acid deposition involves air pollutants falling to Earth's surface as wet or dry forms, causing environmental damage.
- Acid Deposition — a mixture of air pollutants falling as wet or dry forms, forming acids upon contact with water. Example: Acid rain with a pH below 5.6.
- Wet Deposition — atmospheric moisture containing dissolved acidic pollutants falling as precipitation. Example: Acidic rain, snow, or fog.
- Dry Deposition — acidic particles and gases settling on surfaces, becoming acidic runoff when mixed with water. Example: Dust particles settling on buildings.
- Sulphur-Based Acid Formation — sulphur dioxide from fossil fuels reacts with oxygen and water to form sulphuric acid. Example: Burning coal releases SO₂, forming H₂SO₄.
- Nitrogen-Based Acid Formation — nitrogen oxides from combustion processes form nitric acid. Example: Vehicle exhaust emits NO, forming HNO₃.
- Transport and Deposition — pollutants travel long distances, affecting regions far from emission sources. Example: Acid rain affecting countries downwind of industrial areas.
- Impacts on Aquatic Environments — lowers pH of water bodies, harming aquatic life. Example: Fish gill damage and biodiversity loss.
- Impacts on Vegetation and Crops — causes leaf damage and reduces agricultural yields. Example: Premature leaf loss in trees.
- Impacts on Buildings and Infrastructure — accelerates chemical weathering of materials like limestone. Example: Erosion of historic monuments.
Exam Tips
Key Definitions to Remember
- Acid Deposition: A mixture of air pollutants falling as wet or dry forms, forming acids upon contact with water.
- Wet Deposition: Atmospheric moisture containing dissolved acidic pollutants falling as precipitation.
- Dry Deposition: Acidic particles and gases settling on surfaces, becoming acidic runoff when mixed with water.
Common Confusions
- Confusing wet and dry deposition processes.
- Assuming acid deposition only affects areas near pollution sources.
Typical Exam Questions
- What is acid deposition? A mixture of air pollutants falling as wet or dry forms, forming acids upon contact with water.
- How does wet deposition differ from dry deposition? Wet deposition involves precipitation, while dry deposition involves settling of particles and gases.
- What are the impacts of acid deposition on aquatic environments? It lowers pH, harms aquatic life, and disrupts ecosystems.
What Examiners Usually Test
- Understanding of the formation processes of sulphuric and nitric acids.
- Knowledge of the environmental impacts of acid deposition on ecosystems and infrastructure.