5.6+Depletion+of+Stratospheric+Ozone+Group+Project+Notes

5.6 Depletion of Stratospheric Ozone Group Project Notes _________________________________________________________________________________________________________
 * Structure and Composition of the Earth’s Atmosphere (Jordan and LilyAnn) **

- In particular to obj. 5.6.1. (Outline the overall structure and composition of the atmosphere) - Structure and Composition

- Earth

o Third Planet from the Sun o Fifth largest of 8 planets o Largest, most massive, densest - Atmosphere – layer of gas surrounding the planet o Typically temp. Decreases with increase in altitude § Altitude divided into four different layers based on thermal properties · Troposphere, Stratosphere, Mesosphere, Thermosphere · Troposphere – Lowest layer, where all weather occurs, (Mt. Everest reaches less than half way) (extends 500 km. from earth’s surface) Temperature increases because of rapid decrease of thermal molecules, Increase of altitude, less influence of gravity, less dense molecules - Ozone’s interaction with UV light causes increase in temperature - Further you get away from the ozone layer the colder it is o (Acts as a heater or radiator)

- Temperature bounces around, trending on each specific layer o Warms because of unfiltered radiation from the sun o Gases being ionized à releases energy as heat - Hot thermosphere is beneficial because it destroys smaller bits of asteroids that could possible come down to earth and cause destruction - Bad because could cause space shuttle accidents (heat shield tiles can be damaged on launch and descent, blowing up shuttle ex. Discovery and Challenger. )

- Composition

o 2 main gases (99%) Also contains helium, ozone, and other gases § Nitrogen § Oxygen o Variable components (1%)(some components vary over time and location)

o Greenhouse effect

§ Without greenhouse gases surface would be around 90 * Celsius cooler (too cold to live) § Trace amounts of CO2 warm our planet to save life o Ozone (O3) § Forms when… § Important because absorbs 99% of harmful rays § Without could cause more sunburn/skin cancer Atmospheric Chemistry (David, Ching, Charles)

5.6.2. - Ozone prevents harmful rays from - Photoreaction – UV radiation turns into heat energy - Interaction of Ozone and UV Light o 2O2 + 2O à with UV light à O3 § Leads to destruction and breaking down of UV Light § Reverse is true as well o Equilibrium – the reaction goes one way and then back (both ways) § Very critical that equation goes both ways · Too much ozone in the strosphere prevents sunlight from entering the earth making it too cold to live · Too little it can enter the cell and destroy DNA · Depends on the relative concentration of the elements · Important to note that UV Light is not necessarily bad · Ozone absorbs UVB and UVC · UV light key component to both directions of formula § NOTE:: - O2 Very stable – because full valence - O3 is not stable at all – Breaks down on its own in order to form a stable molecular compound o Shortwave, UV, converted into longwave CFC

- Banned in most countries - CFC Forms o Comes from human activity and natural things o Natural -> volcanic eruption o Most comes from coolers of refrigerators and other human products – flame retardants – when things are destroyed the molecules go into the atmosphere and destroy the ozone - **OZONE DEGRADATION -** § Ultraviolet lights hits CFC molecule – Chlorine atom breaks away – Chlorine atom hits ozone molecule – Chlorine atom takes one oxygen atom to create chloride monoxide leaves one molecule of oxygen – Oxygen atom hits chlorine monoxide molecule – two oxygen atoms from an oxygen molecule. Chlorine atom is free and repeats the depletion process § Halogens break apart in UV light, free halogens smash into OZONE molecules causing the already unstable molecule to fall apart § Drives the equilibrium of equation to shift right – less left, more right o WHY IS THE THINNING OCCURING MORE OVER THE ARTIC AND THE ANTARTIC? § (Not holes, but just less concentration) § Because the earth is spinning, causes friction on the gases, causes vortex above the north and the south pole · Concentrates the CFC in those places · Poles end up wandering in the atmosphere due to winds – shifting the contents of the atmosphere · (like upside down tornado) Effect of UV Radiation (Sara, Bernice, and Emily)

What is UV light? - Ultraviolet light o More energetic o Shorter wavelength - Mutation o Error occurred in DNA sequence – causes change in the sequence o Causes covalent bonds to form between nucleotides bases o When DNA is replicated, it’s copied “AA” not the correct “CC”. - Photosynthetic Organisms o When more light exposure à photosynthetic organisms produce more pigment to absorbs more light o UV light does not trigger this reaction o Plankton, under stress, sinks further from the surface to ocean, only to die from too little light - Heath Effect o Non-melanoma and melanoma skin cancer o Skin cancer tumor o Eye damage o Damage of the function of immune system o Aging skin o (Part of this is due to mutation of DNA) - Facts! o 10% decrease in strosphereic ozone could cause and additional 300, 000 non-melanoma and 4500 melanoma skin cancers and more between 1.6 and 1.75 million more cases of cataracts - Effects affect hit Australia the hardest o Country with the most population under the ozone hole o Within the last 20 years of extreme UV light exposure § Causes high levels of skin cancer

Direct Solutions to the Problem (JunHo, Karolina, Bilal) - Problem solving - Reducing CFCs – main contributors to the ozone o Refrigerants (air-conditioning, refrigerators) § Trap heat in lower atmosphere – causing greenhouse effect § Most fridges use CFCs and FCs

§ Making fridges now that use propane and isobutene – no chlorine or fluorine à occurs in natural gases - Reduction Plan o Refrigerant Management Plans § EPA’s Section 608 Refrigerant Recycling Regulations § Newer, smaller, more efficient systems § Safe disposal à clean using oil separation and single or multiple passes through devices such as replaceable core filters dryers · Reduce moisture and acidity and particulate matter · The us Clean Air Act: requirements and permits § Not extremely expensive – however, most cannot afford to simply buy a new fridge § When there is a leak on cars, ozone depletion gases leak out from one season to the next, then you must get it recharged (lots of CFCs leaking out end up contributing to the ozone hole) · Regulations in place for technicians to seal the air-conditioning in cars o Propellants § Compressed gases (nitrogen, carbon dioxide) § Liquefied Gases (petroleum, CFC,…etc.) o How do they work? § Nozzle releases the pressure à compressed gas force pressure on the product up the tube and through the nozzle o What is being done? § Use of CFC banned in USA § Montreal Protocol gets rid of 90% of CFC o Metered-Dose Inhalers § 300 Million People world-wide with asthma · Use 3-4 inhalers per year · As pollution increases asthma increases § 2 types of inhalers · CFC inhalers – Safe for people, dangerous for ozone o Montreal Protocol – Stopped CFC inhalers in particular countries (3-4 years ago) o Count for 70% of world inhalers o Problem § As air pollution gets worse – increase use of inhalers § CFC that comes out of inhalers destroy the ozone o Not CFC inhalers are 3 to 4 times more expensive than CFC inhalers o Refrigerator Recycling, Recovery, Reclamation

- ** Refrigerant RECOVERY involves the removal of a refrigerant from a system and the placement of that refrigerant into a container. ** - ** Refrigerant RECYCLING involves processing used refrigerants to reduce contaminants, then reusing the refrigerant. ** - ** Refrigerant RECLAMATION involves purifying used refrigerant to meet industry product specifications. ** - There are many environmental and economic benefits to be gained from recovery, recycling and reclamation efforts worldwide. The major benefits include o Increased lifetime of refrigeration equipment due to contaminant removal -
 * Minimized atmospheric emissions and reduced environmental impact;
 * Expanded market opportunity for used refrigerant;
 * Reduced environmental compliance costs;
 * Reduced need for new refrigerant; and

Exam:

- Key on 3 things - Evaluate strengths and weaknesses

International Policy Analysis (5.6.6) (Andrea and Linda)

- Reducing CFC’s

- 1976 – Scientific evidence showed dangers in CFCs

o Countries began eliminating CFC usage o However, still much use of CFCs when companies fought back - Montreal Protocol (1987) o Set limits on use and production of CFCs o Very successful o CFCs, chloroform, and harmful gases were meant to be fazed out by the 90s. (and different times depending on developing countries) o With protocol, huge decrease in CFC - Vienna Convention o 1985 Conference o for the protection of the ozone layer o international agreement between countries o no reduction goals, but acts as a framework for reduction o reduction goals laid out in Montreal protocol - UNEP o Adopted Montreal and Vienna o Three-Stage plan for CFCs - Difficulties o Substitutions (CFCs for HFCs) designed to replace the functions of CFCs, not much better, however a significant negative impact o Up to individual country to enforce the CFC law - Future o Ozone depletion rate has slowed down (Global Total EECI) o Stopped the CFC in atmosphere but began a reverse as well

Exam Possibility - Comparing the Montréal protocol to the difficulties faced against it - Science vs. CFC science