OzoneDepletion

Information about OzoneDepletion

Published on February 20, 2008

Author: Siro

Source: authorstream.com

Content

Ozone Depletion:  Ozone Depletion By Matt Stoner and Nicole Crabtree What is Ozone?:  What is Ozone? Composed of three oxygen atoms Unevenly distributed, 90% in Stratosphere Low ozone amounts = damaging to animals, plants, and humans High ozone amounts on ground level = health and agricultural problems CFC’s:  CFC’s Clouroflourocarbons- organic compounds made from carbon, chlorine, flourine, and oxygen Developed in the 1930’s for industrial and commercial applications React in the atmosphere to isolate chlorine Responsible for low ozone levels Extremely stable- do not dissolve in rain Depletion:  Depletion Begins when CFC’s and other ozone depleting substances are emitted into the air Wind mixes substances through tropophere After several years, the substances in the troposphere reach the stratosphere, 10 KM above Earth UV light then begins to break apart the ozone depleting substances Depletion (cont):  Depletion (cont) UV light breaks apart CFC’s to release chlorine UV light breaks apart halons to release Bromine The broken atoms, not intact molecules attack the ozone 1 chlorine atom can destroy 100,000 ozone molecules before being destroyed Depletion (cont):  Depletion (cont) Large increases in chlorine and bromine have upset the natural ozone balance Depleting faster than natural production Natural Ozone Process:  Natural Ozone Process Chemical Process:  Chemical Process Initiated by Polar Night, when high latitudes receive no sunlight Air above cools and vortex is formed Catalytic cycle Cl + O3 ==> ClO + O2 ClO + O ==> Cl + O2 ------------------ net result: O3 + O ===> 2O2 UV Facts:  UV Facts Ozone absorbs 99% of sun’s UV radiation Radiation consists of three bands: A, B, C Ozone blocks out all C (highest energy) Blocks 1/2 of B (2nd highest) Blocks small amount of A (lowest) Results of UV Radiation:  Results of UV Radiation UV radiation causes 95% of all skin cancers 15-40 year lag between high UV exposure and cancer 900,000 Americans annually get skin cancer Melanoma growing 4% a year People who get 3 bad burns before age 20 are 5 time more likely to develop melanoma UV results (cont):  UV results (cont) Best way to avoid this while ozone levels are low: Stay out of sun during peak hours and AVOID the tanning salon Skin cancer exists in three types Squamous, Basal, and Melanoma If ozone depletion persists, skin cancer cases are expected to rise severely Squamous:  Squamous Basal:  Basal Melanoma:  Melanoma Results of Ozone Depletion:  Results of Ozone Depletion Increased UV levels reaching Earth Causes Skin Cancer and Cataracts Impacts phytoplankton activity Alters photochemical reaction rates Increases smog and surface layer ozone Montreal Protocol:  Montreal Protocol Meeting of 36 nations to cut emissions of CFC’s Aimed to reduce emissions by 35% between 1989 and 2000 Also includes halons, carbon tetrachloride, and methyl chloroform Landmark international agreement Montreal (cont):  Montreal (cont) Amended in ‘90, ‘92, and ‘97 As a result CFC production fell 85% China and India have refused to sign Scientists estimate 10-30% of ozone will be depleted in N. hem. By 2080 Clean Air Act:  Clean Air Act Motor Vehicle Air Conditioning Phase-out of Ozone Depletion Substances Product Labeling Motor Vehicle Air Conditioning:  Motor Vehicle Air Conditioning CFC’s have been used as a coolant in motor vehicles Scientists wanted to make sure existing CFC is used efficiently and not wasted This Act lists provisions for new machines to make sure they meet standards for emissions Phase-out:  Phase-out The ban on the production and import of class I ozone-depleting substances (ODS) Exemptions for certain essential uses The phaseout of class II substances Class 1 includes CFC’s, halons, carbon tetrachloride, and methyl chloroform Class II includes all HCFC’s Labeling:  Labeling Establishing label requirements for products manufactured with Class I ozone depleting substances Labeling of Class II substances required by 2015 Made to make public aware of Ozone depletion use Alternatives to CFCs:  Alternatives to CFCs HCFCs HFCs Helium HCs HCFCs:  HCFCs Pros Break down fast 90% less danger to ozone Can be used in aerosol, refigeration, air conditioning, and cleaning agents Cons Greenhouse gases Expensive Health risks unknown Low efficiency Can be degraded into TFA, which can inhibit plant growth HFCs:  HFCs Pros Break down fast Do not contain ozone depleting chlorine Can be used in aerosol, refigeration, air conditioning, and cleaning agents Cons Greenhouse gas Flammable and toxic Produces methyl chloroform which can seriously deplete the ozone layer Slide34:  HFC Emissions Helium:  Helium Pros Effective coolant Cons May become scarce if widely used HCs:  HCs Pros Cheap Not patentable Easily made in developing countries Cons Can be flammable and poisonous if released Increases ground level pollution

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