Chapter 17 Air

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Chapter 17Air Air Pollution

• You are what you breathe!

2
The Atmosphere

• To understand human impacts on our air, we must
  first know a few basic facts about it.
• The atmosphere is composed of four layers

3
The innermost layer is...

• The TROPOSPHERE
• 17 km over sea level
• Known as the weather-breeder

4
Composition of the Troposphere Where you are
right now.

• Nitrogen - 78 (by volume)
• Oxygen - 21
• What happens if O2 fluctuates?
• H2O (g), argon, trace gases
• Carbon Dioxide - ONLY 0.037!
• The earths atmosphere has evolved and changed
  over its 4.6 billion year history
• What may be some important times in evolution?

5
Remember the biogeochemical cycles???
6
Gaseous Biogeochemical CyclingIts not a
personal problem!

• The burning of fossil fuels adds carbon, nitrogen
  oxides and sulfur oxides to the atmosphere.
• Nitrogen fertilizers also add NOx and gaseous
  ammonia to the atmosphere
• Burning coal and oil releases sulfur dioxide,
  which can be converted into sulfuric acid.
• What problems can disruption of these cycles
  cause?

7
What do you think AIR POLLUTION means?

• The presence of one or more chemicals in the
  atmosphere in sufficient quantities and duration
  to cause harm to humans, other forms of life, and
  materials.

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Can there be natural air pollution?

• Particulates from soil forest fires
• volcanoes release SOx
• COx NOx released by forest fires
• Pollen from plants
• CH3 H2S from organic decay
• Sea salt

9
What is Air Pollution?

• Stationary Mobile Sources
• Primary Pollutants
• directly emitted into troposphere and directly
  harmful
• react with one another, air, or uV to form...
• Secondary Pollutants
• Cities usually have more air pollution than rural
  areas
• What are Ozone Action Days?
• Why are they always on hot, sunny summer days?

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Primary Pollutants
CO
CO2
Secondary Pollutants
SO2
NO
NO2
SO3
Most hydrocarbons
HNO3
H2SO4
Most suspended particles
H2O2
O3
PANs
Most
and
salts
Natural
Sources
Stationary
Mobile
Fig. 17.4, p. 422
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Upper LayersPlanes fly here.

• Stratosphere, Mesosphere, Thermosphere
• The second layer is the stratosphere, which
  extends roughly 20-50km above the earth.
• the rise in temperature at the tropopause limits
  mixing between the layers
• less water and a higher concentration of ozone
  than the troposphere

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Stratospheric Ozone

• Ozone (O3) is produced when oxygen interacts with
  UV radiation from the sun
• In the stratosphere, the ozone layer blocks 95
  of the UV rays
• Ozone at ground level is a dangerous pollutant
• Why is it important that these UV rays be blocked?

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40
25
35
20
Stratosphere
30
25
Stratospheric ozone
15
Altitude (kilometers)
Altitude (miles)
20
10
15
10
5
Troposphere
5
0
0
0
5
10
15
20
Fig. 17.3, p. 419
Ozone concentration (ppm)
14
40
Nitric oxide
Nitrogen dioxide
Ozone
30
20
Parts per million
10
0
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
A.M.
Noon
P.M.
Time
Fig. 17.6, p. 424
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More on Air Pollution

• Presence of chemicals in sufficient quantities
  and duration to cause harm to humans, other
  organisms or materials
• Natural sources
• pollen, dust, forest fires, volcanoes, methane,
  hydrogen sulfide
• Where do most anthropogenic (human caused)
  pollution comes from?
• power plants, factories and automobiles

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Major Classes of Air Pollutants

• Oxides of nitrogen, carbon and sulfur
• Volatile Organic Compounds methane, propane,
  CFCs
• Suspended particulate matter
• Photochemical Oxidants - O3 H2O2
• Radioactive substances Rn-222
• Hazardous air pollutants - benzene

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Six Common Air Pollutants
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And the other toxic stuff?
What are VOCs?
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Want to know more?
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Whats being dumped in your air?
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• What characteristics does Chicago have that
  increase or reduce air pollution?
• Think in terms of climate, precipitation,
  topography, industry, population size

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Brown Smog

• Primary Secondary Pollutants react with
  sunlight to produce OZONE
• Noxious brown haze
• Smoke Fog Smog
• Eye Lung irritant
• Photochemical Smog Ozone, PANs and VOCs
• This is why ozone is good up high, bad nearby

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How to make Brown Smog Induce an asthma attack

• N2 O2 high Ts ? NO (from coal power plants)
• NO O2 ? NO2 (in the troposphere -- brown gas)
• NO2 H2O(g) ? nitric acid
• NO2 uV? NO O
• O O2 ? ozone
• HCs O2 NO2 ? PANS they oxidize things

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Solar radiation
Ultraviolet radiation

• N2 O2 high Ts ? NO

NO Nitric oxide
NO O2 ? NO2
O2 Molecular oxygen
NO2 Nitrogen dioxide
H2O Water
NO2 uV? NO O
Hydrocarbons
NO2 H2O(g) ? nitric acid
HCs O2 NO2 ? PANS
O O2 ? ozone
PANs Peroxyacyl nitrates
O3 Ozone
HNO3 Nitric acid
Aldehydes (e.g., formaldehyde)
Photochemical smog
Fig. 17.5, p. 424
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Gray Smog

• Industrial Smog from burning oil coal
• Made of SO2 H2SO4 Soot aerosols
• Smokestacks control local pollution. HOW?
• What abiotic factors affect smog?

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How to turn a perfectly sky blue day gray

• C from Coal O2 ? CO2 CO
• S from Coal O2 ? SO2 (suffocating gas)
• SO2 O2 ? SO3 which then reacts with water vapor
  to produce sulfuric acid
• Sulfuric Acid ammonia ? salts

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Temperature Inversionshot air on top

• Warmer air is less dense than cooler air so
  when warm air is on top of cool air, pollutants
  cant disperse and are stuck.
• This is called a temperature inversion

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• Subsidence Inversion - warm air moves in above
  cool air
• Radiation Inversion - ground cools at night sun
  warms air above
• Harmful if these last for more than a day or two.
  
• LA has thermal inversions about half the year

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Warmer air
Inversion layer
Cool layer
Mountain
Mountain
Valley
Mountains block out sun to reverse nightly
radiation Mountains block out sun to reverse
nightly radiation temperature inversions
Fig. 17.8a, p. 426
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Inversion layer
Mountain range
Subsidence thermal inversions where high pressure
air from coast creates descending warm air masses
Fig. 17.8b, p. 426
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Ultra Fine Particles
Fine Particles
Large Particles
Sea salt nuclei
Fly ash
Carbon black
Pollens
Paint pigments
Tobacco smoke
Cement dust
Milled flour
Combustion nuclei
Coal dust
Oil smoke
Metallurgical dust and fumes
Photochemical smog
Insecticide dusts
Fig. 17.7, p. 425
0.001
0.01
2.5
10.0
100.0
Average particle diameter (micrometers or microns)
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Atmospheric pressure (millibars)
0
200
400
600
800
1,000
120
75
110
65
Thermosphere
100
90
55
80
Heating via ozone
Mesosphere
45
70
60
Altitude (miles)
Altitude (kilometers)
35
50
Stratosphere
40
25
30
15
Ozone layer
20
Heating from the earth
Troposphere
10
5
Pressure 1,000 millibars at ground level
0
80
40
0
40
80
120
Fig. 17.2, p. 418
(Sea Level)
Temperature (C)
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ACID DEPOSITION
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Acid rain

• NORMAL RAINWATER IS ACIDIC!!! (oddly enough)
• Water carbon dioxide react to dorm carbonic
  acid, so natural rainwater has a pH of 5.6
• Anything below that is considered acid deposition
  (or acid rain)

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Acids

• Release hydrogen ions in solution
• pH less than 7
• pH is tenfold
• pH directly related to H ions
• Rain pH 5.6 due to CO2
• What are examples produced in environment?

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Acid Deposition

• What do smokestacks emit?
• What effect do tall smokestacks have on the
  environment?
• What secondary pollutants are produced from
  emissions?

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Acid Deposition

• What do smokestacks emit? Smokestacks emit SO2
  and NOx
• What effect do tall smokestacks have on the
  environment? Reduce local air pollution but
  increase regional air pollution. Blame Canada!
• What secondary pollutants are produced from
  emissions?
• Nitric Sulfuric acids salts

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Acid Deposition Acid Rain
Acid deposition
Wet deposition Rain, snow, fog
Dry deposition particles
Fig. 17.9, p. 428
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Acid Deposition in the US
Coal Burning Industrial Emissions
pH 2.3 on mountain tops!
Fig. 17.10, p. 428
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From western Europe
From Ohio Valley
From China
From Canada
Potential problem areas because of sensitive soils
No natural buffers
Potential problem areas because of air
pollution emissions leading to acid deposition
Current problem areas (including lakes and rivers)
Fig. 17.11, p. 429
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China
Iran
Pakistan
Saudi Arabia
India
Myanmar
Arabian Sea
Thailand
Bay of Bengal
Ethiopia
Indian Ocean
Equator
Winter monsoon blows out and Spring monsoons
blows back
Percentage of direct sunlight intercepted
Very heavy 3545
Heavy 2035
Medium 1020
Fig. 17.12a, p. 429
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Acid Deposition and Humans

• Respiratory diseases

• Toxic metal leaching into drinking water

• Decreased visibility from sulfate particles

• Damage to structures, especially containing
  limestone

• Decreased productivity and profitability of
  fisheries, forests, and farms

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Limestone statue of queen victoria
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Acid Deposition and Aquatic Ecology

• Normal pH is between 6-8

• pH 6

• Undesirable plankton and mosses
• Fish populations decrease

• pH 5

• Fish populations disappear
• Decay at bottom
• Mosses may dominate nearshore

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Acid Deposition and Aquatic Ecology

• pH 4.5

• No fish

• Other effects

• Al leachate fish cant breathe
• Toxic, fatty soluble Hg magnified
• Acid shock from runoff
• Lose buffering ability

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Acid Deposition and Aquatic Systems

• Fish declines

• Undesirable species

• Aluminum toxicity

• Acid shock
• Biological
• magnification of mercury

Fig. 17.13, p. 430
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Acid Deposition on Plants Soil

• Harm to forests and crops begins at pH 5.1

• Direct

• Damaged waxy surface
• Impaired germination

• Indirect

• Essential plant salts leach
• Al3 prevents uptake of nutrients and water
• Toxic heavy metals
• Acid loving mosses hold water, remove air, kill
  fungi
• Weaken trees

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• Weakens trees

• Fig. 17.14, p. 432
• See Connections p. 431

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Whats being done?

• NAPAP National Acid Precipitation Assessment
  Program

• Bad News
• adverse impact on forest ecosystems and waiting
  for effects on others
• tenfold increase in acidity in first 36 cm of
  soil
• Nitrate concentrations in atmosphere have not
  decreases
• No decline in acidity in sensitive aquatic
  systems

• Good news
• Reductions in SO2 and NOx emissions
• Declines in acidity in midwest and northeast
• Sulfate concentrations have dropped in lakes
• SO2 and NOx and particulate matter decreases may
  increase health
• SO2 reduction benefits exceed costs

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Whats can be done to reduce Acid Deposition?

• Energy Efficiency
• Reduce Coal Use
• Natural Gas
• Renewable resources
• Low sulfur coal
• Smokestacks with scrubbers
• Motor vehicle exhaust
• Taxes
• Cleanup Liming and phosphates

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Solutions Preventing and Reducing Air Pollution

• Clean Air Act

• National Ambient Air Quality Standards (NAAQS)

• Primary and secondary standards

• Output control vs. input control