1 / 52

Chapter 15

Chapter 15. Air Pollution and Stratospheric Ozone Depletion. Air Pollution. Air pollution : the introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm living things and materials, or alter ecosystems. Major Air Pollutants.

karik
Download Presentation

Chapter 15

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 15 Air Pollution and Stratospheric Ozone Depletion

  2. Air Pollution • Air pollution: the introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm living things and materials, or alter ecosystems

  3. Major Air Pollutants • Sulfur dioxide (SO2) • Nitrogen oxides (NOx) • Carbon oxides • Particulate matter (PM) • Volatile Organic Compounds (VOCs) • Ozone (O3) • Lead • Mercury

  4. Particulate Matter (PM)

  5. Smog • Portmanteau of smoke + fog • Ex: “Brangelina” • Ex: “Tomkat” • Ex: “Strogiana Lima”

  6. Photochemical (Brown) Smog • NOx + VOCs + sunlight = photochemical smog • Found in areas with a lot of cars (Los Angeles, New York, Sydney, etc.)

  7. Sulfurous (Gray) Smog • SOx + PM + fog = sulfurous smog • Found in areas with a lot of coal burning (Victorian London)

  8. Primary Pollutants • Primary pollutants: polluting compounds that come directly out of the smokestack, exhaust pipe, or natural emission source • Ex: CO, CO2, SO2, NOx, and most suspended particulate matter

  9. Secondary Pollutants • Secondary pollutants: pollutants that have undergone transformation in the presence of sunlight, water, oxygen, or other compounds • Ex: ozone (O3), sulfate (SO42-), and nitrate (NO3-)

  10. Natural Sources of Air Pollution • Volcanoes • Lightning • Forest fires • Plants

  11. Anthropogenic Sources of Air Pollution • Vehicles • Power plants • Industrial processes • Waste disposal

  12. History of Air Pollution in the U.S. • www.youtube.com/watch?v=3PO_3exwN-I

  13. What are some examples of standards? • Every student must achieve a minimum score in the Keystone Exams before graduating high school in Pennsylvania • There may not be more than 2 rodent hairs per 100 grams of peanut butter • Adriana Lima refuses to date Mr. Strogen because she has “standards”

  14. Clean Air Act • Since 1970, the goal of the Clean Air Act has been to reduce the amount of pollution in America’s air • The Act created the National Ambient Air Quality Standards (NAAQS), which sets a maximum level of pollution allowed per pollutant • Six major “criteria” pollutants are regulated: • NO2 • SO2 • Ozone • CO • Lead • Particulate Matter (PM)

  15. Regulation • The Environmental Protection Agency (EPA) has regulatory authority over the air standards • Each state is obligated by law to meet the NAAQS • Areas that do not meet the standards are called “non-attainment”

  16. Percent Change in Air Quality

  17. Comparison of Growth Areas and Emissions, 1980-2008

  18. Number of People Living in Counties with Air Quality Concentrations Above the Level of the NAAQS in 2008

  19. Fig. 17-6 p. 424 Photochemical Smog

  20. Photochemical Smog • http://teachers.redclay.k12.de.us/william.baker/Environmental%20Science%20Files/06%20Air%20Pollution-Solid%20Waste/photochemical_anim.swf

  21. Photochemical Smog

  22. 40 Ozone VOCs Nitric oxides 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

  23. Photochemical Smog www.airinfonow.org/html/makingozone/o3play.htm www.airinfonow.org/html/lungattack/lungplay.htm

  24. Thermal Inversions • Thermal Inversion: when a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below • The warm inversion layer traps emissions that then accumulate beneath it

  25. Acid Deposition

  26. Acid Deposition • Acid deposition: occurs when nitrogen oxides and sulfur oxides are released into the atmosphere and combine with atmospheric oxygen and water, forming the secondary pollutants nitric acid and sulfuric acid • These secondary pollutants further break down into nitrate and sulfate, which cause the acid in acid deposition

  27. Effects of Acid Deposition • Lowering the pH of lake water • Decreasing species diversity of aquatic organisms • Mobilizing metals that are found in soils and releasing these into surface waters • Damaging statues, monuments, and buildings

  28. Effects of Acid Deposition • http://news.discovery.com/videos/earth-acid-rain-eating-washington-dc.html

  29. Ways to Prevent Air Pollution • Catalytic converters on cars • Removing sulfur dioxide from coal by fluidized bed combustion • Scrubbers on smoke stacks • Baghouse filters • Electrostatic precipitators

  30. Catalytic Converter • http://www.youtube.com/watch?v=rmtFp-SV0tY

  31. Wet Scrubber

  32. Baghouse Filter

  33. Electrostatic Precipator

  34. Stratospheric Ozone • The stratospheric ozone layer exists roughly 45-60 kilometers above the Earth • Ozone has the ability to absorb ultraviolet radiation and protect life on Earth

  35. Ozone

  36. Formation & Breakdown of Ozone • First, UV-C radiation breaks the bonds holding together the oxygen molecule O2, leaving two free oxygen atoms: O2 + UV-C 2O • Sometimes the free oxygen atoms result in ozone: O2 + O O3 • Ozone is broken down into O2 and free oxygen atoms when it absorbs both UV-C and UV-B ultraviolet light: O3 + UV-B or UV-C O2 + O

  37. Anthropogenic Contributions to Ozone Destruction • Certain chemicals can break down ozone, particularly chlorine • The major source of chlorine in the stratosphere is a compound known as chlorofluorocarbons (CFCs) • CFCs are used in refrigeration and air conditioning, as propellants in aerosol cans and as “blowing agents” to inject air into foam products, like Styrofoam

  38. Anthropogenic Contributions to Ozone Destruction • When CFCs are released into the troposphere they make their way to the stratosphere • The ultraviolet radiation has enough energy to break the bond connecting chlorine to the CFC molecule • Which can then break apart the ozone molecules

  39. Anthropogenic Contributions to Ozone Destruction • First, chlorine breaks ozone’s bonds and pulls off one atom of oxygen, forming a chlorine monoxide molecule and O2: O3 + Cl ClO + O2 • Next, a free oxygen atoms pulls the oxygen atom from ClO, liberating the chlorine and creating one oxygen molecule: ClO + O Cl + O2 • One chlorine atom can catalyze the breakdown of as many as 100,000 ozone molecules before it leaves the stratosphere

  40. Depletion of the Ozone Layer • Global Ozone concentrations had decreased by more than 10% • Depletion was greatest at the poles • Decreased stratospheric ozone has increased the amount of UV-B radiation that reaches the surface of Earth

  41. Depletion of the Ozone Layer • Destruction is seasonal: • Mid-spring at poles is low O3 concentration point • During winter ice clouds concentrate Cl atoms • They are released during spring, destroying ozone • By summer production is greater than depletion

More Related