5.8. Acid deposition:

5.8.1: Outline the chemistry leading to the formation of acidified precipitations.

Acid deposition can be either wet or dry:
  • Wet deposition - acidic rain, snow, or other precipitation
  • Dry deposition - acidic gas or dry particles, not mixed with water
  • Pollutants can be classified as either primary or secondary

Primary pollutants - those directly emitted by a factory or automobile, such as...
  • SO2 - sulfur dioxide
  • NO and NO2, usually identified as NOx

Secondary pollutants - primary pollutants react with other substances in the atmosphere and create different pollutants, such as...
  • H2SO3 - sulfurous acid
  • H2SO4 - sulfuric acid
  • HNO3 - nitric acid

Fossil fuels combustion -> Sulphur dioxide and nitrogen oxides forming

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5.8.2 Describe three possible effects of acid deposition on soil, water and living organisms.

Direct effects
Toxic Effects
Nutrients Effects
Some organisms cannot tolerate the change in pH
Reduce the population of soil microorganisms
Increase in acidity leads to accelerated leaching of calcium
Damage organisms
Build up of mucus on fish gills and death from lack of oxygen
Living Organisms
Damages tree leaves
Trees uptake toxic aluminum ions from soils
Reduced ability to carry out photosynthesis

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5.8.3 Explain why the effect of acid deposition is regional rather than global.

  • Acid precipitation falls back to Earth rather than entering stratospheric jet stream
  • most areas are downwind of pollution sources
  • Canadian forests damaged by coal-fired power plants in USA
  • Scandinavian and German forests damaged by British coal plants

5.8.4 Describe and evaluate pollution management strategies for acid deposition.

Cars, buses and taxis
  • Reduce Demand for private cars through public transport
  • Promote cycle and bus lanes
  • Restrictions and tolls for car entry to urban areas
  • Promote cleaner fuels and hybrid or electrical models
  • Alternative energy for power generation
  • Reduce total demand through awareness raising
  • Reduce demand through better energy conservation
Release and transfer
Car, buses and taxis
  • Monitor and regulate exhaust emissions
Electricity and industry
  • Use cleaner fuels
  • Clean up acidified emission by using limestone scrubbers
  • Liming of Soil to reduce acidity
  • Monitoring of plankton indicator species to gauge recovery
Living organisms
  • Captive breeding of endangered species

Thing to consider when evaluating:
  • Acid deposition travels with wind and water vapor in the atmosphere
  • The additional environmental impacts of cleaning up emissions e.g. mining, baking and transporting of limestone
  • Monitoring and identify sources may be difficult, as they are often non-point
  • Intergovernmental agreements often require proof and appropriate compensation

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