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Understanding Air Pollution and Ozone Depletion

Discover the impact of pollutants on ecosystems, acid rain effects, ways to prevent air pollution, and the science behind ozone destruction. Learn about major air pollutants, anthropogenic sources, and the stratospheric ozone layer.

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Understanding Air Pollution and Ozone Depletion

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  1. Chapter 15 Air Pollution and Stratospheric Ozone Depletion

  2. 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. Air pollution

  3. Sulfur Dioxide (SO2 aka SOx) Nitrogen Oxides (NOx) Carbon Oxides (esp CO) Particulate Matter Volatiles Organic Compounds (VOCs) Ground-level Ozone (O3) Lead Mercury Major Air Pollutants

  4. Polluting compounds that come directly out of the smoke-stack, exhaust pipe, or natural emission source. Examples: CO, SO2, NOx, and most suspended particulate matter. Primary pollutants

  5. Pollutants that have undergone transformation in the presence of sunlight, water, oxygen, or other compounds. Examples: tropospheric (ground-level) ozone, photochemical smog Secondary pollutants

  6. Volcanoes Lightning Forest fires Plants Natural Sources of Air Pollution

  7. On-road vehicles Power plants Industrial processes Waste disposal Anthropogenic Sources of Air Pollution

  8. Photochemical Smog

  9. 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. Thermal inversion

  10. Acid Deposition

  11. Occurs when nitrogen oxides and sulfur oxides (NOx and SOx) are released into the atmosphere and combine with atmospheric oxygen and water. These form the secondary pollutants nitric acid and sulfuric acid. Acid precipitation (aka acid deposition or acid rain)

  12. 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 Effects of Acid Deposition

  13. 1908 1969

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

  15. BAGHOUSE FILTER Particles are physically removed by a series of filter bags. Baghouse filter

  16. Particles are given a negative charge. Then they are attracted to a positively charged plate where they are held. Periodically the particles are cleaned from the plate. Electrostatic precipitator

  17. Particles are scrubbed from the exhaust stream by water droplets. A water-particle ‘sludge’ is collected and processed for disposal. Scrubber

  18. 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. Stratospheric Ozone – The ‘good’ ozone

  19. First, UV-C radiation breaks the bonds holding together the oxygen molecule, 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 Formation and Breakdown of Ozone

  20. 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. Anthropogenic Contributions to Ozone Destruction

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

  22. 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. Anthropogenic Contributions to Ozone Destruction…

  23. In the mid 1980s global ozone concentrations had decreased by more than 10%. Depletion was greatest at the poles – the so-called ‘hole in the ozone layer’ Decreased stratospheric ozone has increased the amount of UV-B radiation that reaches the surface of Earth. The Montreal Protocol was signed by many countries, banning the use of CFCs and helping to restore the stratospheric ozone layer in the future. Depletion of the Ozone Layer

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

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