Transcript Air Pollution - AaronFreeman

Air and Air Pollution
G. Tyler Miller’s
Living in the Environment
13th Edition
Chapter 17
Key Concepts
 Structure and composition of the atmosphere
 Types and sources of outdoor air pollution
 Types, formation, and effects of smog
 Sources and effects of acid deposition
 Effects of air pollution
 Prevention and control of air pollution
The Atmosphere
• Stratosphere
– 11-30 miles
– Little water vapor
– Ozone layer
• UV filter
• Troposphere
– 11 mile at equator;
8 miles at poles
– weather breeder
– 78% N, 21% O
– Natural heating
• Solar radiation
• Greenhouse effect
Fig. 17-2
The Atmosphere
• Exosphere
• Thermosphere
– ionosphere
– aurorea borialis
– hottest layer
• 1000 C
• Mesosphere
– very little atmosphere
– coldest layer
120
Atmospheric pressure (millibars)
0
200 400 600 800 1,000
75
Temperature
110
Pressure
65
Thermosphere
100
55
Mesopause
80
45
70
60
Stratopause
35
50
Heating via ozone
40
30
25
Altitude (miles)
Altitude (kilometers)
90
Mesosphere
Stratosphere
Tropopause
Ozone “layer”
20
15
Heating from the earth
10
0
(Sea
Level)
5
–80
–40
0
40
80
Temperature (˚C)
120
Troposphere
Pressure = 1,000
millibars at
ground level
40
25
35
Stratosphere
Watch This
25
Stratospheric ozone
15
Altitude (miles)
Altitude (kilometers)
30
20
Benefical Ozone
20
10
15
10
Troposphere
5
Photochemical ozone
0
0
5
Harmful Ozone
5
10
15
Ozone concentration (ppm)
0
20
Air Pollution the presence of one or more chemicals
in the atmosphere in sufficient
quantities and duration to (1) cause
harm to us, other forms of life, and
materials, or (2) alter climate.
Sources of Air Pollution
Where do these sources come from?
TRANSPORTATION + INDUSTRY
Mobile Sources = NOx, CO2, particulate matter, CxHy
Stationary Sources = particulate matter, NOx, SOx, CO2,
hydrocarbons
Major Classes of Pollutants
• PRIMARY
POLLUTANTS
chemicals that enter atm
directly
• Carbon Oxides, NOx,
SO2, particulate matter,
hydrocarbons
• SECONDARY
POLLUTANTS
chemicals that form
from other substances
released into atm
through chemical
reaction
• Ozone
SO3
Major Classes of Air Pollutants
• Carbon oxides
– Carbon monoxide
and carbon dioxide
• Sulfur oxides
– Sulfur dioxide and
sulfur trioxide
• Nitrogen Oxides
– Nitric oxide, nitrogen
dioxide, nitrous oxide
• Volatile Organic
Compounds
– Methane, propane,
CFCs
• Photochemical Oxidants
– Ozone, peroxyacal nitrates
(PAN), hydrogen peroxide
(H2O2)
• Suspended particulate matter
(SPM)
– Dust, soot, asbestos, lead, nitrate,
and sulfate salts
– Sulfuric acid, PCBs, dioxins,
pesticides
• Radioactive substances
– Radon-222, iodine-131,
strontium-90, plutonium-239
• Hazardous Air Pollutants
(HAPS)
Outdoor Air Pollution
Primary pollutants
• pollutants emitted directly into the troposphere in a
potentially harmful form.
Fig. 17-4 p. 421
Outdoor Air Pollution
 Secondary pollutants
• Harmful chemical formed when primary pollutants react
with one another or with the basic components of air.
Fig. 17-4 p. 421
“Criteria” Air Pollutants
Identified by the Clean Air Act 1970
1. Carbon monoxide (CO)
2. Nitrogen Dioxide (NO2)
3. Sulfur Dioxide (SO2)
4. Suspended Particulate Matter (SPM)
5. Ozone (O3)
• Photochemical Oxidants
6. Lead
7. Hydrocarbons
120
Atmospheric pressure (millibars)
0
200 400 600 800 1,000
75
Temperature
110
Pressure
65
Thermosphere
100
55
80
45
70
60
35
50
40
Heating via ozone
25
Ozone “layer”
Heating from the earth
15
Altitude (miles)
Altitude (kilometers)
90
Mesosphere
Stratosphere
30
20
10
0
(Sea
Level)
5
–80
–40
0
40
80
Temperature (˚C)
120
Troposphere
Pressure = 1,000
millibars at
ground level
What is SMOG?
Smog  localized air pollution in urban areas,
mixture of pollutants that form with interaction
with sunlight
• TYPES:
1. Brown
2. Gray
Photochemical Smog
Photochemical (BROWN smog) =
brown haze, light initiates chemical
reactions, complex chemical reactions
Photochemical Reaction
• any chemical reaction activated by light
Photochemical Smog
– a mixture of primary and secondary pollutants
formed under the influence of sunlight
Brown Air Smog
N2 + O2
2 NO + O2
2 NO
@ high temps
2 NO2
NO2 = (yellowish brown gas)
Photochemical Smog Reaction
 Photochemical
oxidants
 NO2
 O3
 PANs
react with and
oxidize certain
compounds in
the atmosphere
Fig. 17-6 p. 424
Industrial (GRAY) Smog
Industrial (GRAY smog) = smoke
pollution, sulfur oxides, particulates
from burning coal/oil, problems in
China/India/Russia due to lack of
pollution controls on smokestack
Industrial Smog
• Gray Smog
– Comes from
burning coal
Sulfur Dioxide
Sulfuric Acid
+ Particulates
• Unburned Carbon
Fig. 17-8 p. 426
What’s location got to do with it?
• Typically, temp.
• Ground air is warmed,
differences help to
rises, then cools =
disperse air pollutants
CONVECTION
preventing harmful
disperses
buildup of air toxins.
concentrations
Temperature Inversions
• TEMPERATURE INVERSION occurs when
• ground aircells colder than upper aircells THUS
trapping harmful pollutants near/closer to
ground
• can lasts hours or days
• cooler air is denser than warmer air above it
• pollutants concentrate is this stagnant cool layer
• no mixing due to convection or differences in
density
Types of Temperature Inversions
Subsidence inversion
Fig. 17-9 p. 427
Subsidence Inversion
warmer mass enters high altitude
region and floats atop a colder air
mass, prevents vertical mixing, can
last hours to days
Types of Temperature Inversions
Radiation inversion
Descending warm air mass
Increasing altitude
Inversion layer
Sea breeze
Mountain
range
Decreasing temperature
Radiation Inversion
occurs at night as ground air cools
faster than air above it, then sun rises
and warms surface dispersing the
pollutants that were trapped during
the night
Where does this occur?
1. Valleys surrounded by mountains
with cloudy/cold weather
Mtns block wind&sun needed to
reverse nightly radiation, thus
concentrations in valley buildup
Where does this occur?
2. near coastlines with sunny climate,
mtns surrounding, winds
EX. Los Angeles
3. leeward side of mtns = side not
exposed to prevailing winds so mixing
is prevented
Leeward Side of Mountain
Regional Outdoor Air Pollution
from Acid Deposition
• Acid Deposition
– Falling of acids and acid
forming compounds from
the atmosphere
– H2SO4, HNO3
Fig. 17-10 p. 428
– Wet deposition
• Acid rain
– Dry deposition
• Acid particles
Acid Deposition in the US
Fig. 17-11 p. 429
Acid Deposition and Humans
•
•
•
•
Respiratory diseases
Toxic metal leaching into drinking water
Decreased atmospheric visibility
Damage to structures, especially
containing limestone (CaCO3)
• Decreased productivity and profitability
of fisheries, forests, and farms
Acid Deposition and Aquatic Systems
• Fish declines
– pH <4.5
• Undesirable
species
• Aluminum
toxicity
• Acid Shock
– Sudden runoff
Acid Deposition, Plants, and Soil
 Nutrient
leaching
 Heavy metal
release
 Weakens trees
Fig. 17-15 p. 432
Indoor Air Pollution
Sick Building Syndrome
Fig. 17-17
p. 434
Most Dangerous Indoor
Pollutants
1. Cigarette smoke
2. Formaldehyde
3. Radon-222 gas
Radon
• Radon-222
• Associated with
uranium (U-238)
and organic
material in rocks
• 2nd leading
cause of lung
cancer
• 4 picocuries
– EPA proposed
standard
Fig. 17-18
p. 436
Reducing
Indoor
Air Pollution
Effects of Air Pollution on Living
Organisms and Materials
Damage to mucous membranes
Respiratory diseases
•Lung cancer
•Asthma – allergic reaction
•Chronic bronchitis – persistent inflammation
•Emphysema – irreversible damage
Nasal cavity
Oral cavity
Pharynx (throat)
(see figure 17.18b)
Trachea (windpipe)
Bronchus
Right lung
Bronchioles
(see figure 17.18c)
Epithelial cell
Cilia
Mucus
Alveolar sac
(sectioned)
Bronchiole
Alveolar duct
Alveoli
Effects of Air Pollution on Living
Organisms and Materials
 Damage to plant leaves and roots
Reduction in primary productivity
Deterioration of materials
(See Table 17-3 p. 440)
Emission Reduction
Wet Scrubber
Cleaned gas
Dirty gas
Clean
water
Electrostatic
Precipitator
Wet
gas
Dirty water
Solutions: Air Pollution
• Clean Air Acts
– 1970, 1977, 1990
– National Ambient Air Quality Standards
(NAAQS)
• Six outdoor criteria pollutants
• EPA regulates chemicals by using criteria from
risk assessment methods
• Sets maximum permissible levels
• Primary Standard – human health
• Secondary Standard – environmental and
property damage
Solutions: Air Pollution
• Possible Economic Solutions $$
• Clean Air Act enabled emissions trading policy
• Allows power plants to buy/sell SO2 pollutions
rights
• Can only emit certain amount of SO2
• If you emit less than your allotted amount , you
receive pollution credits
Can US Air Pollution Laws
Be Improved?
• Continue to rely mostly on pollution cleanup
rather than prevention.
• Fail to increase fuel-efficiency standards for
cars and light trucks.
• Not adequately regulating emissions from
inefficient two-cycle gasoline engines.
• Do little to reduce emissions of carbon dioxide
and other greenhouse gases.
The Next Steps
• Integrating government policies for
energy and air pollution.
• Improving energy efficiency.
• Relying more on lower-polluting and more
climate-benign natural gas.
• Increasing use of renewable energy.
• Regulating the air quality for an entire
region or airshed with primary emphasis
on prevention.