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Air Pollution and Stratospheric Ozone Depletion
Chapter 15 Air Pollution and Stratospheric Ozone Depletion
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Gases in the Atmosphere
Nitrogen 78% of Earths atmosphere most abundant atmospheric gas Oxygen 21 % of Earths atmosphere 2nd most abundant Other 1% is a mixture of Carbon Dioxide, helium, methane, helium and ozone.
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Air Pollution Major Air Pollutants
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. Major Air Pollutants Sulfur Dioxide Particulate Matter Lead Mercury Nitrogen Oxides Volatiles Organic Compounds Carbon Oxides Ozone
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Book Page 412
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Particulate Matter
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Natural Sources of Air Pollution
Volcanoes Lightning Forest fires Plants
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Anthropogenic Sources of Air Pollution
On-road vehicles Power plants Industrial processes Waste disposal
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Primary Pollutants Secondary 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. Secondary Pollutants Secondary pollutants- pollutants that have undergone transformation in the presence of sunlight, water, oxygen, or other compounds. Examples: ozone, sulfate and nitrate
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Primary Pollutants Secondary Pollutants 2 Sources
NO NO2 SO3 Most hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs SO4 2 – Most NO3 – and salts Sources Natural Stationary Mobile
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Also Called GROUND LEVEL OZONE
Smog Photochemical smog When nitrogen oxides (NO and NO2 coming from cars and industry) react with volatile organic hydrocarbons due to UV radiation (sunlight) and produce a mix of primary and secondary pollutants Cars + NO2 + hydrocarbons Pollution (smog) Also Called GROUND LEVEL OZONE sunlight
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Photochemical Smog Stratosphere Ground Level
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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.
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Acid Deposition Acid deposition- occurs when NO2 and SO2 are released into the atmosphere and combine with atmospheric oxygen and water. These form the secondary pollutants nitric acid (HNO3) and sulfuric acid (H2SO4). These secondary pollutants further break down into nitrate and sulfate which cause the acid in acid deposition.
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Acid Deposition
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Effects of Acid Deposition
Lowering the pH of lake water Decreasing species diversity of aquatic organisms Mobilizing metals (Aluminum) that are found in soils and releasing these into surface waters Damaging statues, monuments, and buildings Affects pipes and releases lead
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Ways to Prevent Air Pollution
Removing sulfur dioxide from coal by fluidized bed combustion Catalytic converters on cars Scrubbers on smoke stacks Baghouse filters Electrostatic precipitators
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Baghouse Filter
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Electrostatic Precipitator
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Scrubber
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Stratospheric Ozone Formation of Ozone
Ozone is found in the stratosphere Ozone has the ability to absorb ultraviolet radiation and protect life on Earth. Formation of Ozone First, UV-C radiation breaks the bonds holding together the O2 molecule, leaving two free oxygen atoms: O2 + UV-C -> 2O The free oxygen atoms then react with other O2 molecules creating ozone: O2 + O -> O3
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#1 #2 #3 How ozone is produced in the stratosphere. Ozone #4
2 Oxygen molecules + 1 Free Oxygen combine
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Stratospheric Ozone is in Danger
Satellites have measured a decrease in O3 over the past few decades. Areas over the poles have holes that allow dangerous radiation from the sun to enter earths atmosphere Human activities have caused this (CFC’s released into the Atmosphere)
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Where do most come from? Byproducts of foam production, refrigeration, and air conditioning called chlorofluorocarbons (CFCs), as well as hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) Emissions generated by industrial processes and automobiles.
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Anthropogenic Contributions to Ozone Destruction
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. O3 + Cl -> ClO + O2 One chlorine atom can catalyze the breakdown of as many as 100,000 ozone molecules before it leaves the stratosphere.
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Current Ozone Hole Pics
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Indoor Air Pollution Pollution can be 2-5 times higher inside
Inside cars can be 18 times higher 18 sources of cancer come from indoor air pollution Sick building syndrome- term for people getting sick from air pollutants (particularly in new buildings) Top 4 Cigarette Smoke Formaldehyde Radon Particulates
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Para-dichlorobenzene
Tetrachloroethylene Chloroform 1, 1, 1- Trichloroethane Formaldehyde Benzo-a-pyrene Nitrogen Oxides Styrene Tobacco Smoke Asbestos Radon-222 Methylene Chloride Carbon Monoxide
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Indoor Air Pollution Formaldehyde Colorless gas
Used to make household materials furniture Drapes and upholstery Adhesive in carpeting and wallpaper insulation
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Indoor Air Pollution Radon-222 Naturally occurring radioactive gas
Can’t see, taste, or smell Found in underground deposits of minerals Buildings above deposits – enter through cracks and openings Second leading cause of lung cancer Need to have house tested and sealed (comes up through the foundation)
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Outlet vents for furnaces and dryers
Open window Openings around pipes Cracks in wall Slab joints Wood stove Cracks in floor Sump pump Clothes dryer Furnace Slab Radon-222 gas Uranium-238 Soil
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