Lecture Notes: Acid Deposition (Topic 6.4 under IBE SS6 Atmospheric Systems and Society)

Introduction to Acid Deposition

• Continuation from Topic 6.3 (Photochemical Smog)
• Focus on impacts of Nitrous Oxides and Sulfur Dioxide from fossil fuel combustion and their role in acid deposition

Acid Deposition Explained

• Primary Pollutants: Sulfur dioxide and nitrous oxides from fossil fuel combustion
• Secondary Pollutants: Formed through chemical reactions; result in dry (ash, particles) or wet (rain, snow) deposition
  • Acid Deposition/Acid Rain: Precipitation with acidic components (sulfuric/nitric acids)
  • Normal Rain pH: Around 5.6 (slightly acidic)
  • Acid Rain pH: Between 4.2 and 4.4, can be lower

Pathway and Effects of Acid Rain

• Emission to Deposition: Sulfur dioxide and nitrous oxides transform and fall as wet/dry deposition
• Impact on Environment:
  • Damage to soil, forests, streams, lakes
  • Example: Dying trees in Czech Republic
• Specific Impacts:
  • Soil and surface water acidification in Brazil
  • Variation in pH levels affects biodiversity

Biodiversity Impact

• Animal Tolerance: Some animals tolerate acidic water, others can't survive
• Effects:
  • Fish eggs fail to hatch at pH 5
  • Aluminum toxicity affects fish
  • Reduction in aquatic biodiversity

Impact on Forests and Nutrients

• Leaves, buds show damage; nutrients leached away
• Aluminum Toxicity: Released into streams, affects fish

Impact on Human Constructions

• Limestone buildings/statues dissolve
• Historical sites (Taj Mahal, Mayan ruins) at risk

Human Health Implications

• Dry Deposition: Small particles penetrate lungs, risk of lung diseases

Summary of Effects on Environment

• Direct effects: On aquatic organisms, forests
• Indirect effects: Solubility of metals; nutrient leaching
• Cross-Border Issues: Pollution downwind affects regions beyond source country

Pollution Management Strategies

1. Altering Human Activity:

   • Energy conservation (turn off lights, use public transport)
   • Use alternative energy (ethanol, renewable sources)
   • Low sulfur fuels, remove sulfur before burning

2. Regulating Emission Points:

   • Chimney scrubbers and catalytic converters
   • Effective but costly and may have secondary impacts

3. Cleanup and Restoration:

   • Liming lakes and rivers (neutralizes acidity)
   • Effective but needs regular repetition
   • Regulatory measures (international agreements)

Historical Context

• Timeline of regulations and agreements (e.g., US Clean Air Act, UN conventions)
• Effective regulations have shown signs of environmental recovery

Conclusion

• Regulations and pollution management strategies have had a positive impact
• Ongoing need for international cooperation and effective policy implementation

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Resources

• Slides by: Dr. Nina Markham
• Textbook: IB ESS textbook
• Image Sources: URLs provided on slides

End of the lecture on Acid Deposition under IBE SS6 Atmospheric Systems and Society.