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Unformatted text preview: Lecture 22: Ozone Important points: Do NOT get the ozone hole mixed up with ______________ Ozone has very little to do with __________________! There are ____ major ozone issues 1. Ozone: too much in the troposphere 2. Ozone: too little in the stratosphere 3. Causes of depletion: CFCs, N2O 4. Montreal Protocol Issue #1: Ozone as a pollutant _____________________ _________________ ______________________ Urban smog component Reduces ___________ and growth in many _______________ Soybeans, winter wheat, red clover, sugar maple, white pine, red oak, etc. Ozone as a pollutant
Annual $$ losses in reduced plant growth (corn, wheat, soybeans, peanuts) $1.9 4.5 billion Air quality: yesterday Ozone as a pollutant http://airnow.gov/ 1 Precursors to "bad" ozone... Where do they come from? Ozone as a pollutant Solutions: 1. Cleaner burning fuels, 2. Better equipment on vehicles: catalytic converters cut emissions by 87%. 3. Reduce the number of vehicles on the road. Mass-transit systems. What can you do? Conserve energy at home and school Reduce air pollution from cars, trucks, etc. by keeping equipment properly _____. During the summer, fill your gas tank during the cooler evening hours and be careful not to _________________ Use household and garden chemicals wisely. Use low VOC paints and solvents. When the air is unhealthy, limit physical exertion outdoors Issue #2: Ozone in the __________ Ozone shield:
Protective ozone layer in the upper atmosphere that reduces the amount of ______________ radiation that hits the earth's surface. Ozone hole: Reduction in ozone over the Arctic & Antarctic during winter. Thinning of the Ozone Layer Ozone Hole Evidence from satellites of thinning of the Ozone layer led to the Montreal Protocol for reducing CFCs 1979 1982 1984 1986 1988 1990 1992 1994 1997 1999 Darkest blue areas represent regions of maximum ozone depletion 2004 2 The worsening ozone hole Why is ozone shield decreasing?
Major cause: ________________________
http://ozonewatch.gsfc.nasa.gov/ Inert (non-reacting), synthetic compounds, first used in 1930s. - Freon (air conditioners) - Halon (fire extinguishers) - Old-style styrofoam coffee cups - Hair spray propellants - Other propellants (hard to know...) Atmospheric chemistry When CFCs reach stratosphere, (exposed to UV radiation), they break up into chlorine, etc. Each chlorine molecule may destroy 100,000 ozone molecules. Montreal Protocol (1987, 1990) International agreement Banned ________ - by 2000 (developed countries) - By 2010 (less developed) Second conference moved these target dates up. Emission rates dropped by >50% since 1988. CFC Production Another reason for decline of protective ozone layer: nitrous oxide 3 The ozone hole may not recover this century, as was expected Today's UV forecast... more in stratosphere in stratosphere more CH4 CO2 N2O CO2 CO 2
More greenhouse gases in troposphere What can you do? Use approved ______________ in air conditioners & refrigerators Make sure technicians that work on your car or home air conditioners or refrigerator are certified to recover the refrigerant ______________ air conditioning units before refilling them. Wear sunscreen! (SPF 15+) http://www.epa.gov/sunwise/uvindex.html 4 ...
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- Fall '08