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Environmental Science: Toward a Sustainable Future Richard T. Wright. Chapter 21. Atmospheric Pollution PPT by Clark E. Adams. Atmospheric Pollution. Air-pollution essentials Major air pollutants and their sources Impacts of air pollutants: health and environment - PowerPoint PPT Presentation
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Environmental Science: Toward a Sustainable Future Richard T. Wright
Atmospheric Pollution PPT by Clark E. Adams
Chapter 21
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
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
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
The Hydroxyl Radical: Nature’s Cleanser
The Appearance of Smog
Impacts of Smog: Temperature Inversion
Air Pollution Effects
Adversely affects human health Damages crops and forests Highly corrosive
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
Major Air Pollutant Sources
Major Air Pollutants: Primary (see next slide)
Primary pollutants derived directly from burning fuels and wastes Particulates Hydrocarbons Carbon monoxide Nitrogen oxides Sulfur dioxides
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
Comparison of Growth vs. Emissions
Acid Deposition
pH Scale
Acid precipitation = pH <5.5
pH = measurement of H+ ions in solution
Major Sources of SO2 Emitters
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
Impacts of Air Pollutants on Human Health
Chronic example: lead poisoning Acute example: death – Bhopal, India Carcinogenic example: lung cancer
The Respiratory System
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
Ozone Impact on Crop Yields
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
Impacts of Air Pollutants on the Environment
Forests Increased plant vulnerability to natural
enemies Increased soil erosion Increased flooding Increased sedimentation of waterways
Impacts of Air Pollutants on the Environment
Materials Loss of color Oxidation Corrosion Decreased real estate values
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
Trends in Automobile Emissions
Impact of Buffers on Acid Deposition
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
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
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)
Match Control Strategies on Right with Air Pollutants on Left
Particulates VOCs Automobile
emissions Acid rain
Catalytic converter Reasonably
available control strategy (RACT)
Scrubbers Coal washing
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
Industry’s Response to Title IV
Fuel switching Scrubbers Emissions allowance trading Using low-sulfur coals
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
End of Chapter 21