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Air Pollution

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					                Air Pollution
• What controls the level?
   – Amount of pollutants entering the air.
   – Amount of space into which the pollutants are
     dispersed.
   – Mechanisms that remove pollutants from the air.


• When is it a concern?
   – Exceed a threshold level
   – Threshold level depends on concentration and
     duration of exposure, i.e. dose.
Dose = (concentration X exposure)
    Major Primary Pollutants
1. Suspended          5. Sulfur oxides
   particulate        6. Heavy metals
   matter
2. Volatile organic   7. Air toxics
   compounds             (radon)
3. Carbon
   monoxide
4. Nitrogen oxides
PANs = peroxyacetyl nitrates
The Hydroxyl Radical:
Nature’s Cleanser (?)
     Sources of These Emissions
            (Fig. 22-13)?

1)   Sulfur dioxides
                          A) Fuel combustion
2)   Nitrogen oxides
                          B) Transportation
3)   VOC’s                C) Industrial
4)   Particulate matter       processes
5)   Carbon monoxide
Emission Trends
    Air Pollution Effects
• Adversely affects human health
   – Chronic
   – Acute
   – Carcinogenic
• Damages crops and forests
   – Necrotic
   – Chlorotic
   – Disease and Pest Susceptibility
• Damage to material & aesthetics
   – Corrosion
   – Oxidation
   – Smog
Smog I
Smog II
Temperature Inversions
Photochemical Oxidants (Troposphere Ozone and PANs




Vehicles!
Four Forms of Acid Deposition
            pH Scale
pH = measurement of H ions in solution




   Acid precipitation = pH < 5.5
    Acid Deposition in the U.S.


2/3 sulfuric
1/3 nitric




                    Coal burning
                    power plants
    Effects of Acid Deposition on
        Aquatic Ecosystems
• Alteration of plant and animal
  reproduction
• Leaching of other toxic elements, e.g., Al
• Eutrophic to seemingly oligotrophic
  conditions
• Total loss of biota from aquatic
  ecosystems
• Alterations of food chains
    Effects of Acid Deposition on
         Forest Ecosystems
•   Leaching of nutrients
•   Release of aluminum into solution
•   Rapid changes in soil chemistry
•   Reduced growth and diebacks of plants
    and animals
•   Increased flooding
•   Increased plant vulnerability to natural
    enemies
•   Increased soil erosion
•   Increased sedimentation of waterways
Ecosystems Impacts are Not Equal.
Limestone Buffers Acid Deposition.
Clean Air Act of 1970, 1977, 1990
• Identifies most widespread pollutants:
  e.g., particulates, SO, CO, NO, lead =
  criteria pollutants
• Set ambient standards = levels that
  protect environmental and human health
• Set national ambient air quality standards
• Set national emission standards for
  hazardous air pollutants
  Title IV Clean Air Act 1990
• Reduce SO emission 50% below 1980
  levels
• Improve methods of reducing SO
  emissions
• Allow emissions allowances and
  trading
• Emissions purchases
• Reduce NO emissions
      Future Responses to Air
          Pollution Control
•   Increase fuel efficiency
•   Emission-free vehicles
•   Improving mass transit systems
•   Reducing commuting distances

    What are some potential societal reactions
    to these control measures?

				
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posted:8/2/2012
language:English
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