Transcript Atmospheric Science and Air Pollution

13
Atmospheric Science
and Air Pollution
PowerPoint® Slides prepared by
Thomas Pliske, Heidi Marcum, and Nicole Lantz
© 2010 Pearson Education Canada
This lecture will help you understand:
• The Earth’s atmosphere
• Outdoor pollution and
potential solutions
• Stratospheric ozone
depletion
• Acidic deposition and its
consequences
• Indoor air pollution and
solutions
• [Note: we will skip over
most of the stuff on the
structure of the atmosphere]
13-2
HOUSEKEEPING ITEMS



A reminder that the life-cycle analysis is due on
November the 8th or 9th, depending on when you
have class.
How was Chris Foote?
Did anyone see the cover story in the Saturday
Vancouver Sun on the decline in shark
populations?
source: National Geographic
Central Case: The rain and the big nickel
“Despite Canada’s success at reducing acid-causing
emissions, acid deposition is still affecting our
environment.”
– Environment Canada
• Mining and refining in Sudbury, Ontario generates high
SO2 emissions, leading to acid rain
• 1972: Built a 380m superstack to disperse emissions
• 1980s: cleaned emissions prior to releasing them
• Acidification and remediation studied at the
Experimental Lakes Area in northwestern Ontario
• Better ecological awareness today
13-4
The atmosphere and weather
• Atmosphere = the thin layer of gases that surrounds Earth
- Absorbs radiation and moderates climate
- Transports and recycles water and nutrients
- 78% nitrogen gas, 21% oxygen gas, 1% other gases
- Its four layers differ in temperature, density and
composition
• Minute concentrations of permanent (remain at stable
concentrations) and variable gases (varying concentrations)
• Human activity is changing the amounts of some gases
13-5
Earth’s atmosphere
FIGURE 13.1
13-6
The atmosphere is layered
FIGURE 13.2
13-7
The lower layers of the atmosphere
• Troposphere = lowest layer
- Air for breathing, weather
- Temperature declines with altitude
- Tropopause = limits mixing between troposphere
and the layer above it
• Stratosphere = 11-50 km (7-31 mi) above sea level
- Drier and less dense, with little vertical mixing
- Colder in its lower regions
- Contains UV radiation-blocking ozone, 17-30 km
(10-19 mi) above sea level
13-8
The higher layers of the atmosphere
• Mesosphere = 50-80 km (31-56 mi) above sea level
- Extremely low air pressure
- Temperatures decrease with altitude
• Thermosphere = atmosphere’s top layer
- Extends upward to 500 m (300 mi)
13-9
Atmospheric properties include temperature,
pressure, and humidity
• Atmospheric pressure =
measures the force per
unit area produced by a
column of air
• Relative humidity = the
ratio of water vapor a
given volume of air
contains to the amount it
could contain at a given
temperature
FIGURE 13.3
13-10
Solar energy heats the atmosphere
FIGURE 13.4
13-11
Solar energy heats the atmosphere
• The spatial relationship between the Earth
and sun determines the amount of solar
energy striking the Earth
• Energy from the sun
- Heats air
- Moves air
- Creates seasons
- Influences weather and climate
• Solar radiation is highest near the equator
13-12
Solar energy creates seasons
FIGURE 13.5
13-13
Solar energy creates seasons
• Because the Earth is tilted
- Each hemisphere tilts toward the sun for half the
year
- Results in a change of seasons
- Equatorial regions are unaffected by this tilt, so
days average 12 hours through the year
13-14
Solar energy causes air to circulate
FIGURE 13.6
13-15
Solar energy causes air to circulate
• Convective circulation = less dense, warmer air
rises and creates vertical currents
- Rising air expands and cools
- Cool air descends and becomes denser, replacing
warm air
- Influences both weather and climate
13-16
The atmosphere drives weather and climate
“Climate is what we expect; weather is what we get.”
- Mark Twain
• Weather = specifies atmospheric conditions over short
time periods and within a small geographic areas
• Climate = describes patterns of atmospheric conditions
across large geographic regions over long periods of
time
13-17
Air masses interact to produce weather
• Front = the boundary between
air masses that differ in
temperature, moisture, and
density
• Warm Front = the boundary
where warm moist air replaces
colder, drier air
• Cold Front = the boundary
where colder, drier air
displaces warmer, moister air
FIGURE 13.7
13-18
Air masses have different atmospheric
pressures
• High-pressure system = air that moves away from a
center of high pressure as it descends
- Brings fair weather
• Low-pressure system = air moves toward the low
atmospheric pressure at the center of the system and
spirals upward
- Clouds and precipitation
13-19
Thermal inversion
• Normally there is vertical
mixing
• Thermal inversion = a layer
of cool air occurs beneath a
layer of warmer air
- Inversion layer = the
band of air in which
temperature rises with
altitude
- Denser, cooler air at the
bottom of the layer resists
mixing
FIGURE 13.8
13-20
Large-scale circulation systems produce
global climate patterns
• Hadley cells = a pair of convective air currents near the
equator where surface air warms, rises, and expands
• Ferrel cells and polar cells = convective cells that lift
air and create precipitation at 60 degrees latitude north
and south
• These interact with Earth’s rotation to produce global
wind patterns
• Coriolis effect = the north-south air currents of the
convective cells appear to be deflected from a straight
path
13-21
Climate patterns and moisture distribution
FIGURE 13.9
13-22
Wind patterns
• Doldrums = near the equator
- Few winds
• Trade winds = between the equator and 30 degrees
latitude
- Blow from east to west
• Westerlies = from 30 to 60 degrees latitude
- Originate from the west and blow east
13-23
Outdoor air pollution
• Air pollutants = gases and particulate material added
to the atmosphere
- Can affect climate or harm people
• Air pollution = the release of pollutants
• Outdoor (ambient) air pollution = pollution outside
- Has recently decreased due to government policy
and improved technologies in developed countries
- Developing countries and urban areas still have
significant problems
13-24
Natural sources can pollute: dust storms
• Dust storms = Hundreds
of millions of tons of dust
are blown westward across
the Atlantic Ocean by trade
winds every year
FIGURE 13.10
- From Africa to the
Americas
- Unsustainable farming
and grazing, erosion and
desertification
13-25
Natural sources can pollute: volcanoes
• Release large quantities of
particulate matter, sulfur
dioxide & other gases
• Can remain for months or
years
• Aerosols = reflect sunlight
back into space and cool the
atmosphere and surface
FIGURE 13.10
13-26
Natural sources can pollute: fires
• Pollutes atmosphere with soot and gases
• Over 60 million hectares of forests and grasslands burn
per year
• Fires are made more severe by human action
- Decades of fire suppression
- Fires from “slash-and-burn” clearing of forests
13-27
We create various types of outdoor air
pollution
• Point Sources = specific spots where large quantities of pollutants
are discharged (power plants and factories)
• Nonpoint Sources = more diffuse, consisting of many small
sources (automobiles)
• Primary Pollutants = directly harmful and can react to form
harmful substances (soot and carbon dioxide)
• Secondary Pollutants = form when primary pollutants interact or
react with constituents or components of the atmosphere
(tropospheric ozone and sulfuric acid)
13-28
CEPA identifies harmful airborne substances
• 1999: Canadian Environmental Protection Act
• Environment Canada groups pollutants of greatest
concern into four categories:
- Criteria air contaminants
- Persistent organic pollutants
- Heavy metals
- Toxic air pollutants
13-29
Criteria air contaminants
• Criteria pollutants = pollutants judged to pose
especially great threats to human health
• Sulphur dioxide (SO2)
• Nitrogen dioxide (NO2)
• Particulate matter (PM)
• Volatile organic compound (VOC or VOX)
• Carbon monoxide (CO)
• Ammonia (NH3)
• Tropospheric ozone (O3)
13-30
weighing
the issues
Investigating your region’s
air quality
How polluted is the air near where you live? Go to the
National Pollutant Release Inventory (NPRI) website at
www.ec.gc.ca/pdb/npri/npri_home_e.cfm. Use the
Google Earthmapping tool to check on the amounts of
pollutants released in your own province or local area.
• Are there any specific facilities in your area that are
major emitters of atmospheric pollutants?
• Were you aware of the existence of these emitters,
previously?
13-31
Government agencies share in dealing with
air pollution
• Federal
- Managed through Environment Canada
(primarily)
- 1999: Canadian Environmental Protection Act
(CEPA)
- Enters into international agreements (e.g.
Montreal Protocol, Kyoto Protocol)
- Enters into transboundary agreements with the
U.S. (e.g. Canada-United States Air Quality
Agreement)
13-32
Government agencies share in dealing with
air pollution
• Provincial/territorial
- Managed through each environment ministry
- Canadian Council of Ministers of the
Environment (CCME)
- Harmonization Accord, Canada-Wide Standards
Sub-Agreement, National Ambient Air Quality
Objectives
13-33
Government agencies share in dealing with
air pollution
• Municipal
- Only Montreal and Greater Vancouver regulate
sources of air pollution
- Most municipalities raise public awareness
13-34
Monitoring shows that many forms of air
pollution have decreased
FIGURE 13.13
13-35
Pollutants for the Air Quality Health Index
show little to no improvement
FIGURE 13.13
13-36
Reasons for the decline in some pollutants
• Cleaner-burning vehicles and catalytic converters decrease
carbon monoxide
• Permit-trading programs and clean coal technologies
reduce SO2 emissions
• Scrubbers = technologies that chemically convert or
physically remove pollutants before they leave the
smokestacks
• Phase-out of leaded gasoline
• Improved technologies and federal policies
13-37
Canada is attempting to “turn the corner” on
air pollution
• 2007: Turning the corner: An Action Plan to Reduce
Greenhouse Gases and Air Pollution
- Targets for greenhouse gas (GHG) and criteria air
contaminant (CAC) emissions
FIGURE 13.16
13-38
Smog is the most common, widespread air
quality problem
• Smog = unhealthy mixtures of
air pollutants over urban areas
• Industrial (gray air) smog =
industries burn coal or oil
- Occurs in cooler, hilly areas
FIGURE 13.17
- Government regulations in
developed countries reduced
smog
- Coal-burning industrializing
countries face significant
health risks
13-39
Photochemical (brown air) smog is
produced by a complex series of reactions
• Light-driven reactions of
primary pollutants and
normal atmospheric
compounds
• Morning traffic exhaust
releases pollutants
FIGURE 13.18
• Irritates eyes, noses, and
throats
• Vehicle inspection programs
have decreased smog
13-40
Industrial smog
Photochemical smog
• 17.16
FIGURE 13.17
FIGURE 13.18
13-41
weighing
the issues
Congestion charging
• Does your city, or the nearest major city to you, suffer
from air pollution?
• Do you think this city should adopt a congestioncharging program like London’s?
• What benefits would your city enjoy from such a
program, and what problems might it bring?
• What other steps should this city take to tackle
pollution?
• Are there any specific facilities in your area that are
major emitters of atmospheric pollutants?
13-42
Air quality is a rural issue, too
• Airborne pesticides from farms
• Industrial pollutants drifting from cities, factories and
powerplants
• Feedlots, where cattle, hogs, or chickens are raised in
dense concentrations
- Voluminous amounts of methane, hydrogen sulfide,
and ammonia
- People living or working nearby have high rates of
respiratory problems
13-43
Industrializing nations are suffering
increasing air pollution
• Outdoor pollution is increasing
• China has the world’s worst air pollution
- 80% of Chinese cities have emissions above the
safety threshold
• Southern Asian brown cloud = a 3 km-thick layer
of pollution that reduces sunlight, affects climate,
decreases productivity, and kills thousands each
year
13-44
Synthetic chemicals deplete stratospheric
ozone
• Ozone layer = ozone in the lower stratosphere
- 12 ppm concentrations effectively block incoming
damaging ultraviolet radiation
• Chlorofluorocarbons (CFCs) = chemicals that attack
ozone
- 1 million metric tons/year were produced
- Releases chlorine atoms that split ozone
13-45
The “ozone hole”
• Ozone hole = ozone
levels over Antarctica
had declined by 4060%
• Global ozone
depletion causes skin
cancer, harms crops
and decreases ocean
productivity
FIGURE 13.19
13-46
There are still many questions to be
resolved about ozone depletion
• Will ozone depletion spread from the polar regions to
encompass mid-latitude regions?
• What is the actual relationship between ozone depletion
and human health impacts?
• What are the other potential impacts of ozone depletion
(e.g. on ecosystems)?
• Are the substitute chemicals that are being proposed in
international agreements definitely less damaging to the
stratospheric ozone layer?
13-47
The Montreal Protocol addressed ozone
depletion
• 1987: Montreal Protocol = 180 nations agreed to cut CFC
production in half
- Follow-up agreements deepened cuts, advanced timetables and
addresses other ozone-depleting chemicals
- Today, production and use of ozone-depleting chemicals has
decreased 95%
- The ozone layer is beginning to recover
• Challenges still face us
- CFCs will remain in the stratosphere for a long time
- Nations can ask for exemptions to the ban
13-48
The Montreal Protocol is a success
• Considered the biggest environmental success
story
- Policymakers included industry in helping
solve the problem
- Adaptive management strategy allowed
changes in response to new scientific data,
technological advances, and economic
figures
• The Montreal Protocol can serve as a model for
international environmental cooperation
13-49
Acid deposition is another transboundary
pollution problem
• Acidic deposition = the deposition of acid, or acidforming pollutants, from the atmosphere onto Earth’s
surface
- Acid rain = precipitation of acid
- Atmospheric deposition = the wet or dry deposition
on land of pollutants
• Originates from burning fossil fuels
- release sulfur dioxide and nitrogen oxides
- react with water to form sulfuric and nitric acids
13-50
Sources of acid deposition
FIGURE 13.21
13-51
Effects of acid deposition on ecosystems in
Northeastern North America
• Accelerated leaching of base cations from soil
• Accumulation of sulphur and nitrogen in soil
• Hindering of plant uptake of water and nutrients
• Caused calcium to leach from needles of red spruce
• Increased mortality of sugar maples
• Acidified many lakes
• Lowered lakes’ capacity to neutralize further acids
• Elevated aluminum levels in surface waters
• Negatively affected entire food webs
13-52
Acid deposition has not been reduced as
much as scientists had hoped
• New technologies such as scrubbers have helped
• SO2 emissions are lower
• NOx emissions are higher
• Acid deposition’s effects are worse than predicted
13-53
Indoor air pollution
• Indoor air contains higher concentrations of pollutants
than outdoor air
- 6,000 people die per day from indoor air pollution
• The average person in North America is indoors at least
90% of the time
- Exposed to synthetic materials (insecticides,
cleaning fluids, plastics, and chemically treated
wood)
- 1973-74: ventilation systems were sealed off and
windows put in that did not open, trapping
pollutants inside, leading to “sick building
syndrome”
13-54
Indoor air pollution in the developing world
arises from fuelwood burning
• Burning wood, charcoal,
dung, crop wastes for
cooking and eating
• Kills 1.6 million people
each year
FIGURE 13.25
[solar ovens are one
alternative]
• Causes pneumonia,
bronchitis, allergies,
cataracts, asthma, heart
disease, cancer and
premature death
13-55
Tobacco smoke and radon are the most
dangerous indoor pollutants in the
developed world
• Secondhand smoke from cigarettes is especially
dangerous
- Containing over 4000 dangerous chemicals
- Causes eye, nose, and throat irritation
- Smoking has declined in developed nations
• After cigarette smoke, radon gas is the second-leading
cause of lung cancer in the developed world
- Colourless, odourless gas that can seep into buildings
13-56
Many VOCs pollute indoor air
• VOCs = volatile organic compounds
• Released by everything from plastics and oils to
perfumes and paints
• Most VOCs are released in very small amounts
• Unclear health implications due to low
concentrations
• Also include pesticides, which are found indoors
more often than outdoors due to seepage
• Formaldehyde, which leaks from pressed wood
and insulation, irritates mucous membranes and
induces skin allergies
13-57
Sources of indoor air pollution
FIGURE 13.27
13-58
Living organisms can pollute indoors
• Tiny living organisms can also pollute
• Includes dust mites and animal dander worsen asthma
• Fungi, mold, mildew, airborne bacteria cause severe
allergies, asthma, and other respiratory ailments
• Sick building syndrome = a sickness produced by
indoor pollution with general and nonspecific
symptoms
- Solved by using low-toxicity building materials and
good ventilation
13-59
weighing
the issues
How safe is your
indoor environment?
Think about the amount of time you spend indoors.
Name the potential indoor air quality hazards in your
home, work, or school environment.
• Are these spaces well-ventilated?
•What could you do to make the indoor spaces you use
safer?
13-60
We can reduce indoor air pollution
• In developed countries:
- Use low-toxicity material
- Monitor air quality
- Keep rooms clean
- Limit exposure to chemicals
• In developing countries:
- Dry wood before burning
- Cook outside
- Use less-polluting fuels (natural gas)
13-61
Conclusion
• Indoor air pollution is a potentially serious health
threat
• Outdoor air pollution has been addressed by
government legislation and regulation in
developed countries
• Improvement is required in reducing acidic
deposition, photochemical smog
• Continued challenge as less-wealthy nations
industrialize
13-62
QUESTION: Review
The major component of Earth’s atmosphere is …
a)
b)
c)
d)
Nitrogen gas
Oxygen gas
Argon gas
Water vapor
13-63
QUESTION: Review
Ozone in the _________ is a pollutant, but in the ______
is vital for life
a)
b)
c)
d)
Stratosphere, troposphere
Troposphere, stratosphere
Troposphere, tropopause
Stratosphere, thermosphere
13-64
QUESTION: Review
_____ is defined as the ratio of water vapor in the
atmosphere compared to the amount the atmosphere
could contain
a)
b)
c)
d)
Atmospheric pressure
Ozonification
Temperature
Relative humidity
13-65
QUESTION: Review
If you were on a sailing ship going from Europe to
Canada, you would want to be in the ________
a)
b)
c)
d)
Doldrums
Trade winds
Westerlies
Polar cell
13-66
QUESTION: Review
Which criteria pollutant is colorless, odorless, and poses a
risk to humans, even in small amounts?
a)
b)
c)
d)
Sulfur dioxide
Nitrogen dioxide
Tropospheric ozone
Carbon monoxide
13-67
QUESTION: Review
The Montreal Protocol addressed _______
a)
b)
c)
d)
Global warming, and was not successful
Criteria pollutants, and was successful
Ozone depletion, and was successful
Acid deposition, and was successful
13-68
QUESTION: Interpreting Graphs and Data
What does this graph show about the mesosphere?
a) It contains the most ozone
b) It is a very thin layer
c) Temperature decreases
with increasing altitude
d) Temperature increases with
increasing altitude
FIGURE 13.2
13-69
QUESTION: Viewpoints
Should the government be able to prevent restaurants
from allowing smoking, to protect people from
secondhand smoke?
a) Yes; I don’t want to be exposed to this form of
pollution
b) Yes, only if the restaurant agrees
c) No, let the restaurant owner decide
d) No; I want to be able to smoke in a restaurant
13-70