This lecture will help you understand:

2. 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

3. 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

4. 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

5. 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

6. Earth’s atmosphere FIGURE 13.1 13-6

7. The atmosphere is layered FIGURE 13.2 13-7

8. 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

9. 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

10. 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

11. Solar energy heats the atmosphere FIGURE 13.4 13-11

12. 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

13. Solar energy creates seasons FIGURE 13.5 13-13

14. 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

15. Solar energy causes air to circulate FIGURE 13.6 13-15

16. 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

17. 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

18. 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 13-18 FIGURE 13.7

19. 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

20. 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

21. Large-scale circulation systems produce global climate patterns • Hadley cells =a pair of convective air currents near the equator wheresurface 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

22. Climate patterns and moisture distribution FIGURE 13.9 13-22

23. 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

24. 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

25. 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 • From Africa to the Americas • Unsustainable farming and grazing, erosion and desertification FIGURE 13.10 13-25

26. 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

27. 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

28. 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

29. 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

30. 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

31. weighingtheissues 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

32. 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

33. 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

34. 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

35. Monitoring shows that many forms of air pollution have decreased FIGURE 13.13 13-35

36. Pollutants for the Air Quality Health Index show little to no improvement FIGURE 13.13 13-36

37. 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

38. 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

39. 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 13-39

40. 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 13-40

41. Industrial smog Photochemical smog • 17.16 FIGURE 13.17 FIGURE 13.18 13-41

42. weighingtheissues 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? 13-42

43. 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

44. 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

45. 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

46. 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 13-46

47. 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

48. 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

49. 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

50. 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 13-50