13Atmospheric Science

and Air Pollution

© 2010 Pearson Education Canada

PowerPoint® Slides prepared by Thomas Pliske, Heidi Marcum, and Nicole Lantz

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]

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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

• 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

“Despite Canada’s success at reducing acid-causing emissions, acid deposition is still affecting our environment.”

– Environment Canada

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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

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Earth’s atmosphere

FIGURE 13.1

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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

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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)

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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

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Solar energy heats the atmosphere

FIGURE 13.4

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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

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Solar energy creates seasons

FIGURE 13.5

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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

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Solar energy causes air to circulate

FIGURE 13.6

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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

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The atmosphere drives weather and climate

• 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

“Climate is what we expect; weather is what we get.”- Mark Twain

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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

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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

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Climate patterns and moisture distribution

FIGURE 13.9

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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

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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

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• Dust storms = Hundreds of millions of tons of dust are blown westward across the Atlantic Ocean by trade winds every year

- From Africa to the Americas

- Unsustainable farming and grazing, erosion and desertification

Natural sources can pollute: dust storms

FIGURE 13.10

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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

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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

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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)

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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

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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)

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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?

weighing

the issues

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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)

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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

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Government agencies share in dealing with air pollution

• Municipal

- Only Montreal and Greater Vancouver regulate sources of air pollution

- Most municipalities raise public awareness

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Monitoring shows that many forms of air pollution have decreased

FIGURE 13.13

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Pollutants for the Air Quality Health Index show little to no improvement

FIGURE 13.13

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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

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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

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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

- Government regulations in developed countries reduced smog

- Coal-burning industrializing countries face significant health risks

FIGURE 13.17

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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

• Irritates eyes, noses, and throats

• Vehicle inspection programs have decreased smog

FIGURE 13.18

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• 17.16

Industrial smog Photochemical smog

FIGURE 13.18FIGURE 13.1713-41

Congestion charging

• Does your city, or the nearest major city to you, suffer from air pollution? • Do you think this city should adopt a congestion-charging 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?

weighing

the issues

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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

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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

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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

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The “ozone hole”• Ozone hole = ozone

levels over Antarctica had declined by 40-60%

• Global ozone depletion causes skin cancer, harms crops and decreases ocean productivity

FIGURE 13.19

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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?

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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

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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

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Acid deposition is another transboundary pollution problem

• Acidic deposition = the deposition of acid, or acid-forming 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

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Sources of acid deposition

FIGURE 13.21

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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

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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”

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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

• Causes pneumonia, bronchitis, allergies, cataracts, asthma, heart disease, cancer and premature death

FIGURE 13.25

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[solar ovens are onealternative]

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

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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

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Sources of indoor air pollution

FIGURE 13.27

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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

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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?

weighing

the issues

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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)

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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

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QUESTION: ReviewThe major component of Earth’s atmosphere is …

a) Nitrogen gasb) Oxygen gasc) Argon gasd) Water vapor

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QUESTION: ReviewOzone in the _________ is a pollutant, but in the ______ is vital for life

a) Stratosphere, troposphereb) Troposphere, stratospherec) Troposphere, tropopaused) Stratosphere, thermosphere

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QUESTION: Review_____ is defined as the ratio of water vapor in the

atmosphere compared to the amount the atmosphere could contain a) Atmospheric pressureb) Ozonificationc) Temperatured) Relative humidity

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QUESTION: ReviewIf you were on a sailing ship going from Europe to Canada, you would want to be in the ________

a) Doldrumsb) Trade windsc) Westerliesd) Polar cell

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QUESTION: Review

Which criteria pollutant is colorless, odorless, and poses a risk to humans, even in small amounts?

a) Sulfur dioxideb) Nitrogen dioxidec) Tropospheric ozoned) Carbon monoxide

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QUESTION: ReviewThe Montreal Protocol addressed _______

a) Global warming, and was not successfulb) Criteria pollutants, and was successfulc) Ozone depletion, and was successfuld) Acid deposition, and was successful

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QUESTION: Interpreting Graphs and Data

What does this graph show about the mesosphere?

a) It contains the most ozoneb) It is a very thin layerc) Temperature decreases

with increasing altituded) Temperature increases

with increasing altitude

FIGURE 13.213-69

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 agreesc) No, let the restaurant owner decide d) No; I want to be able to smoke in a restaurant

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