1. OZONE DEPLETION & CLIMATE CHANGE (Ch 20)

2. ELECTROMAGNETIC SPECTRUM

4. TYPES OF UV RADIATION 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): 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: 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.

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

7. I MPACTS ON ENVIRONMENTAL SYSTEMS  Decreased primary productivity (land & ocean)  Damage to fish/amphibians / mammals  Disrupt food chain  Effects on food crops (beans, wheat, rice, corn)

9. ATMOSPHRE LAB

10. Cumulative Graph should look like…

11. 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 VIDEOOZONE VIDEO (2:20)

13. CHEMICAL CLASSES OF OZONE DESTROYERS CHLOROFLOUROCARBONS (CFC'S) CHLOROFLOUROCARBONS (CFC'S) 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. HALOCARBONS/HALONS (ODS) HALOCARBONS/HALONS (ODS) Highly reactive group 17  Cl, Br, F Sources: Styrofoam, Solvents, Soil Fumigant, Fire Extinguishers

16. OZONE PHLEMISTRY WKST

17. O 2 becomes O 3 1)O 2 + UV  ● O + ● O 2) O 2 + ●O  O 3 O 3 becomes O 2 1)O 3 + UV  O 2 + ● O 2) O 3 + ●O  O 2 + O 2 CFCs degrades O 3 into O 2 1)CCl 2 F 2 + UV  ● CClF 2 + ● Cl 2) ●Cl + O 3  ClO● + O 2 NO degrades O 3 into O 2 1) NO + O 3  NO 2 + O 2 A IRPLANES !

18. OZONE CHEMISTRY for the visual learners

19. STEP 1: NATURAL FORMATION OF OXYGEN

20. STEP 2: Natural Formation of Ozone in the STRATOSPHERE

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

22. PER CHLORINE ATOM BROKEN OFF BY UV RADIATION FROM CFC’S, 100-300,000 OZONE MOLECULES CAN BE BROKEN DOWN (~900,000 O 3 MOLEUCLES PER CFC!) OZONE CFC Free Radical Chlorine Free Radical Oxygen CLO* STEP 4: CFC’s BREAKING DOWN OZONE (anthropogenic causes)

25. Ozone over Antarctica ANTARCTIC OZONE HOLEANTARCTIC OZONE HOLE (16 MIN) OZZY OZONEOZZY OZONE (10 MIN)

26. THOMAS MIDGLEY