Chapter 15 Air Pollution and Stratospheric Ozone Depletion

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 plants, animals, and materials such as buildings, or to alter ecosystems. Anthropogenic Sources

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

4. Anthropogenic Sources of Air Pollution

5. Major Air Pollutants • Sulfur Dioxide • Nitrogen Oxides • Carbon Oxides • Particulate Matter • Volatiles Organic Compounds • Ozone • Lead • Mercury

6. Primary Pollutants • Primary pollutants- polluting compounds that come directly out of the smoke-stack, exhaust pip, or natural emission source. • Examples: CO, CO2, SO2, NOx, and most suspended particulate matter.

7. Secondary Pollutants • Secondary pollutants- pollutants that have undergone transformation in the presence of sunlight, water, oxygen, or other compounds. • Examples: ozone, sulfate and nitrate

10. Big Six: Sulfur Dioxide (SO2) • Sources • Byproduct of combustion • S content of organism • Volcanic eruptions • Forest Fires • Effects • Respiratory irritant • Odorlesspungent • Plant distress • Limits • 0.14ppm for 24h • 1ppm

11. Big Six: Nitrogen oxides (NOx) • Sources • Combustion byproduct • Forest Fires • Lightning • Soil Microbes • Effects • Trophospheric ozone • Photochemical smog • Respiratory distress/plant distress • Limits • 0.053ppm annual • 2ppm

12. Big Six: Carbon oxides • Sources • Combustion • Complete and incomplete • Respiration • Effects • Headaches, asphyxia • Climate change • Limits (CO) • 9 ppm (8 hours) • 50 ppm

13. %⇌PPM ×10000 ÷ 10000

14. Big Six: Particulate Matter • PM10 v. PM 2.5 • Sources • Road dust • Volcanoes, Forest Fires • Dust storms • Effects • Respiratory problems (aggravate preexisting) • Limits (PM10) • 150g/m3 over 24h • 600g/m3

16. Big Six: Lead • Sources • Combustion • Gasoline additive • Paint chips • Effects • CNS toxicity • Limits • 0.15 g/m3

18. Big Six: Ozone • Sources • UV-A, -B, -C (natural) • CFCs/Photochemicals • Effects • Respiratory distress • Emphysema, asthma • “Good up high, but bad nearby” • Limits • 0.08ppm for 4 days/year • 0.6ppm for 2 hours

19. Other Air Pollutants • Photochemical oxidants • Sunlight acting on oxides (SO2 and Nox) • Mixes with PM to form smog • Volatile Organic Compounds • Easily vaporize at room temp • Hydrocarbons • Natural and anthropogenic

22. London Fog Los Angeles Smog

23. Photochemical Smog Formation

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.

26. Acid Deposition • Acid deposition- occurs when nitrogen oxides and sulfur oxides are released into the atmosphere and combine with atmospheric oxygen and water. These form 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. Acid Deposition

28. 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

29. Acid Deposition Effects

30. Ways to Prevent Air Pollution • Sulfur and NO Emissions • Removing sulfur dioxide from coal by fluidized bed combustion • CaCO3 + SO2 CaSO4 • Lower burn temperatures • NO CO tradeoff • Catalytic converter

31. Ways to Prevent Air Pollution • Particulate Matter • Gravitational settling • Disposal concerns • Scrubbers on smoke stacks • Baghouse filters • Electrostatic precipitators • Smog • VOC control

32. Baghouse filters

33. Scrubber

34. ElectrostaticPrecipitator

35. Ways to Prevent Air Pollution • 1967 Air Quality Act - no standards • 1970 Clean Air Act(standards) / Earth Day • 1980 Lead drops 50% in environment & drops 37% in blood • 1980 Vice President Bush proposes ending phase out as the chairman of Regulatory Relief • 2000 Milestones: • Carbon Monoxide: 31% decrease • Sulfur Dioxide: 27% decrease • VOC’s down 42% • Particulate Matter* (PM-10): 71% decrease • Lead: 98% decrease

36. Innovative Pollution Control • Spilled gasoline, lighter fluid • Cracking down on bakeries? • Bye bye fireplaces! • Every other day drive • Sulfur permits

37. DO THE MATH • The United states has declined from 23.5 million metric tons in 1982 to 10.3 million metric tons of sulfur emissions in 2008. Given the data presented, calculate the total percentage reduction and the annual percentage reduction of SO2 emissions.

38. 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.

39. Formation and Breakdown of Ozone • First, UV-C radiation breaks the bonds holding together O2 O2 + UV-C  2O • Sometimes results 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 Location is Critical!!!

40. Anthropogenic Contributions to Ozone Destruction • Chlorine • 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.

41. Anthropogenic Contributions to Ozone Destruction

42. 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. NET REACTION: O3 + O  2O2

43. Recent Ozone Measurements

44. 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. Why the poles?

45. Reduced levels of ozone Normal levels of ozone Depletion of the Ozone Layer Dobson Units 100DU=1mm 1DU = .01mm • Stratospheric ozone layer

46. Cancer

47. Efforts to Reduce Ozone Depletion The Montreal Protocol Montreal Protocol = 196 nations agreed to cut CFC production in half by 2000

48. Indoor Air Pollutants • Wood, animal manure or coal used for cooking and heating in developing countries. • Asbestos • Carbon Monoxide • Radon • VOCs in home products • Tobacco smoke

49. Indoor airpollution

50. Radon risk across the U.S. Radon