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OZONE DEPLETION & CLIMATE CHANGE (Ch 20)

OZONE DEPLETION & CLIMATE CHANGE (Ch 20). ELECTROMAGNETIC SPECTRUM. UV – A (AGING) : Low energy. Thought to contribute to premature aging and wrinkling of the skin and has recently been implicated as a cause of skin cancer.  UV – B (BURNING) : Medium energy.

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OZONE DEPLETION & CLIMATE CHANGE (Ch 20)

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  1. OZONE DEPLETION & CLIMATE CHANGE(Ch 20)

  2. ELECTROMAGNETIC SPECTRUM

  3. UV – A (AGING): Low energy. Thought to contribute to premature aging and wrinkling of the skin and has recently been implicated as a cause of skin cancer.  UV – B (BURNING): Medium energy. UVB is more dangerous than UVA and has been implicated as a major cause of skin cancers, sunburning and cataracts.  UV – C: High energy. UVC is extremely dangerous but does not reach the earth’s surface due to absorption in the atmosphere.  Most of the radiation below 290 nm is absorbed by the ozone in the upper atmosphere.  Depletion of this layer increases the amount of UVC reaching ground level. TYPES OF UV RADIATION

  4. OZONE LAYER DECREASES…. INCREASED UV RADIATION ENTERS HEALTH

  5. Decreased primary productivity (land & ocean) Damage to fish/amphibians/ mammals Disrupt food chain Effects on food crops (beans, wheat, rice, corn) Impacts on environmental systems

  6. ATMOSPHRE LAB

  7. Cumulative Graph should look like…

  8. Ozone Depletion • Ozone- molecule consisting of 3 oxygen atoms • Benefit to humans because it absorbs harmful UV radiation • Ozone layer is being depleted because of the addition of chemicals (esp. CFC’s) that break apart the ozone molecule Ozone Video (2:20)

  9. CHEMICAL CLASSES OF OZONE DESTROYERS CHLOROFLOUROCARBONS (CFC'S) HALOCARBONS/HALONS (ODS) • No significant natural sources identified • Source: Air conditioning, Aerosol propellants, solvents, styrofoam • GREAT longevity • takes 5-7 years for CFC’s to go from ground to upper atm. • Highly reactive group 17 • Cl, Br, F • Sources: Styrofoam, Solvents, Soil Fumigant, Fire Extinguishers

  10. OZONE PHLEMISTRY WKST

  11. O2 becomes O3 • O2 + UV  ●O + ●O • 2) O2 + ●O  O3 • O3 becomes O2 • O3 + UV  O2 + ●O • 2) O3 + ●O  O2 + O2 • CFCs degrades O3 into O2 • CCl2F2 + UV  ●CClF2 + ●Cl • 2) ●Cl + O3  ClO● + O2 NO degrades O3 into O2 1) NO + O3 NO2 + O2 Airplanes!

  12. OZONE CHEMISTRYfor the visual learners

  13. STEP 1:NATURAL FORMATION OF OXYGEN

  14. STEP 2: Natural Formation of Ozone in the Stratosphere

  15. Step 3: Natural Breakdown of Ozone in the STRATOSPHERE

  16. STEP 4: CFC’s BREAKING DOWN OZONE (anthropogenic causes) Free Radical Chlorine CFC OZONE Oxygen Free Radical Oxygen CLO* PER CHLORINE ATOM BROKEN OFF BY UV RADIATION FROM CFC’S, 100-300,000 OZONE MOLECULES CAN BE BROKEN DOWN (~900,000 O3 MOLEUCLES PER CFC!)

  17. Ozone over Antarctica Antarctic Ozone Hole(16 min) Ozzy Ozone(10 min)

  18. THOMAS MIDGLEY

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