Environmental Science: Toward a Sustainable Future Richard T. Wright

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Environmental Science Toward a Sustainable
Future Richard T. Wright
Chapter 21

• Atmospheric Pollution PPT by Clark E. Adams

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Atmospheric Pollution

• Air-pollution essentials
• Major air pollutants and their sources
• Impacts of air pollutants health and environment
• Bringing air pollution under control
• Unresolved issues

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Incorrect Assumptions about Air Pollutants

• There are threshold levels of tolerable air
  pollutants
• Dilution is the solution to air pollution
• Air pollutants can be assimilated by nature
• Air pollutants do not travel
• Air pollution accidents will not happen

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Pollutants and Atmospheric Cleansing

• Air pollutants gases and aerosols in the
  atmosphere that have harmful effects
• Level of air pollution determined by
• The amount of pollutants entering the air
• The amount of space into which the pollutants
  dispersed
• Mechanisms that remove pollutants from the air

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The Hydroxyl Radical Natures Cleanser
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The Appearance of Smog
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Impacts of Smog Temperature Inversion
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Air Pollution Effects

• Adversely affects human health
• Damages crops and forests
• Highly corrosive

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Major Air Pollutants and Their Sources (see Table
21-1)

• Suspended particulate matter
• Volatile organic compounds
• Carbon monoxide
• Nitrogen oxides

• Sulfur oxides
• Heavy metals
• Ozone
• Air toxics

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Major Air Pollutant Sources
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Major Air Pollutants Primary (see next slide)

• Primary pollutants derived directly from burning
  fuels and wastes
• Particulates
• Hydrocarbons
• Carbon monoxide
• Nitrogen oxides
• Sulfur dioxides

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Major Pollutants Secondary (see next slide)

• Secondary air pollutants derive from reactions
  that occur between primary pollutants and other
  atmospheric chemicals
• Ozone
• PANs
• Acids sulfuric and nitric

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Comparison of Growth vs. Emissions
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Acid Deposition
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pH Scale
pH measurement of H ions in solution
Acid precipitation pH lt5.5
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Major Sources of SO2 Emitters
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Impacts of Air Pollutants on Human Health

• Chronic gradual deterioration of a variety of
  physiological functions over a period of years
• Acute life-threatening reactions within a period
  of hours or days
• Carcinogenic cancer-causing

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Impacts of Air Pollutants on Human Health

• Chronic example lead poisoning
• Acute example death Bhopal, India
• Carcinogenic example lung cancer

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The Respiratory System
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Impacts of Air Pollutants on the Environment

• Plants
• Necrotic kills plant cells
• Chlorotic destroys chlorophyll, reducing
  photosynthesis
• Increases susceptibility to disease and pests

Ozone most serious pollutant
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Ozone Impact on Crop Yields
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Impacts of Air Pollutants on the Environment

• Forests
• Leaching of nutrients
• Release of aluminum into solution
• Rapid changes in soil chemistry
• Reduced growth and diebacks of plants and animals

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Impacts of Air Pollutants on the Environment

• Forests
• Increased plant vulnerability to natural enemies
• Increased soil erosion
• Increased flooding
• Increased sedimentation of waterways

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Impacts of Air Pollutants on the Environment

• Materials
• Loss of color
• Oxidation
• Corrosion
• Decreased real estate values

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Effects of Acid Deposition

• Alteration of plant and animal reproduction
• Leaching of other toxic elements, e.g., aluminum
• Eutrophic to oligotrophic conditions
• Total loss of biota from aquatic ecosystems
• Alterations of food chains

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Trends in Automobile Emissions
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Impact of Buffers on Acid Deposition
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Bringing Air Pollution under Control

• Clean Air Act identifies most widespread
  pollutants e.g., particulates, SO, CO, NO, lead
  criteria pollutants
• National Ambient Air Quality Standards (NAAQS)
  set levels that protect environmental and human
  health

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Bringing Air Pollution under Control

• NAAQS also set national ambient air quality
  standards
• National Emission Standards for Hazardous Air
  Pollutants set national emission standards for
  hazardous air pollutants

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Control Strategies

• Command-and-control regulate air pollution so
  criteria pollutants remain below primary standard
  level
• Lack of enforcement and compliance
• 37 reduction of air pollutants
• Forced compliance with state implementation plan
  (SIP)

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Match Control Strategies on Right with Air
Pollutants on Left

• Catalytic converter
• Reasonably available control strategy (RACT)
• Scrubbers
• Coal washing

• Particulates
• VOCs
• Automobile emissions
• Acid rain

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Title IV Clean Air Act 1990

• Reduce SO emissions 50 below 1980 levels
• Improve methods of reducing SO emissions
• Allow emissions allowances and trading
• Emissions purchases
• Reduce NO emissions

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Industrys Response to Title IV

• Fuel switching
• Scrubbers
• Emissions allowance trading
• Using low-sulfur coals

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Unresolved Issues

• Costs versus benefits of air pollution control
• Status of new source review and enforcement
• Improving fuel efficiency hybrid cars
• Improving mass transit systems
• Reducing commuting distances

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End of Chapter 21