Transcript Air pollutants - Saint Leo University Faculty

Energy & Its Impact on Global
Society
Jerome K. Williams, Ph.D.
Saint Leo University
Dept. Mathematics & Sciences
Chapter 8: Air Pollution &
Energy Use
• Properties & Motion of Atmosphere
• Air Pollutants & Sources
– Acid Rain
– Photochemical Smog
• Environmental Issues: Air-Quality Standards
Properties & Motion of
Atmosphere
• Air is a mixture of gases (Table 8.1)
• Majority of air is nitrogen (78%) and oxygen
(21%)
Properties & Motion of
Atmosphere
• Air pollutants are substances added by
humans that are toxic or irritants to animals,
vegetation, or property
Properties & Motion of
Atmosphere
• Examples of Air pollutants
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carbon monoxide (CO) carbon dioxide (CO2)
sulfur dioxide (SO2)
sulfur trioxide (SO3)
heavy metals (lead, mercury, cadmium)
iron
carbon soot (ash)
Properties & Motion of
Atmosphere
• Vertical motion of air and winds are important
mechanisms for dispersing air pollutants
• Temperature inversion occurs when warm air
layer lies on top of cooler part; thus stopping
atmospheric dispersion (mixing) of air
pollutants
Air Pollutants & Their Sources
• Air Pollutants: Three Varieties
– Gases
– Particulates (small particles of solids)
– Aerosols (small droplets liquid suspended in gas)
– 135 million tons emitted into air over USA (this
amounts to 1.3 kg/day/person)
Air Pollutants & Their Sources
• Air Pollutants: Sources
– Stationary (Power Plants, Industries)
– Moving Sources (Vehicles)
– Natural Sources (Volcanoes, Biological Decay,
Forest Fires, Ocean Spray)
– Pollutant levels measured in parts per million
(ppM) unit
Air Pollutants & Their Sources
• Carbon monoxide (CO)
– Odorless, colorless, poisonous gas
– Produced primarily in vehicle engines by the
incomplete combustion of carbon found in
gasoline fuel
– Binds to hemoglobin in blood; prevents oxygen
from reaching cells in body
Air Pollutants & Their Sources
• Sulfur oxides (SO2 & SO3)
– Colorless gas; suffocating odor; powerful irritant
– Comes from burning of coal (6% sulfur by weight)
– Sulfur reacts with oxygen to form SO2 and
continues to form SO3
– Oxides combine with water vapor to produce acid
rain which falls back to Earth
Air Pollutants & Their Sources
Acid Rain Video
• http://www.youtube.com/watch?v=Nc6j7zz1_
do
Air Pollutants & Their Sources
• Nitrogen oxides (NO, NO2)
– Origin: fossil fuel burning in vehicles and power
plants
– Photochemical Smog (observe brown haze due to
NO2)
– Also plays a role in acid rain phenomenon
– Ozone plays a role in process
Photochemical Smog Video
• http://www.youtube.com/watch?v=8BPFyQ2CSU
Air Pollutants & Their Sources
• Indoor Air Pollution
– Indoor air pollution concentrations can be many
times greater than outside levels
– 80% of time spent indoors (home & work or
school)
– Table 8.4
Environmental Issues: Air-Quality
Standards
• Clean Air Act (1970)
– NAAQS (National Ambient Air Quality Standards)
was established to reduce levels of six pollutants
linked to human health effects
– Sulfur oxides, nitrogen oxides, particulates, ozone,
carbon monoxide and lead
Environmental Issues: Air-Quality
Standards
• Mini-Paper: Clean Air Act (Pollutant Levels)
– Each student assigned one air pollutant
– Determine air pollutant concentration that is
acceptable today in US; compare to level in 1970s
– How does one reduce the aforementioned
pollutant while preserving a favorable benefit to
cost ratio?
– Essay is 600 – 800 words; due November 10
Problems
• 10, 20, 23