Chemist Chargers Presentation

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Title: Ozone DepletionSection: 5B

Submit date: 7 March 2012

Lecturer name: Dr Shayma A.Shaker

Group name :Chemist chargersGroup Members Name & ID

Kavenesh Sevandran AM86242

Pardeep Singh Gill A/L Atma Singh AM86259

Saravanan A/L Baskaran AM86059

Ruthraganapathy A/L Radhakrishnan AM86229


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Introduction to ozone deptionIntroduction to ozone deption

The ozone layer is a belt of naturally occurring ozone gas that sits9.3 to 18.6 miles (15 to 30 kilometers) above Earth and serves as ashield from the harmful ultraviolet B radiation emitted by the sun.

Ozone is a highly reactive molecule that contains three oxygenatoms. It is constantly being formed and broken down in the highatmosphere, 6.2 to 31 miles (10 to 50 kilometers) above Earth, inthe region called the stratosphere.


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OZONE LAYER DEPLETION


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Destruction of ozone by chlorine

Molecular oxygen is broken down in the stratosphere by solarradiation to yield atomic oxygen, which then combines withmolecular oxygen to produce ozone. The ozone is then destroyed bychlorine atoms.


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Ozone destruction by UV rays

UV radiation from the sun releases theradicals Cl and ClO.Ozone is a highly unstable molecule soit readily donates its extra oxygenmolecule to free radical species such ashydrogen, bromine, and chlorine.These compound species act as catalystsin the breakdown of ozone molecules


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The ozone depletion process


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The Causes of Ozone DepletionCFC are very stable, nontoxic and environmentally safe in the loweratmosphere, which is why they became so popular in the first place.Their very stability allows them to float up, intact, to the stratosphere.They are broken apart by the intense ultraviolet light, releasing chlorine.Chlorine demolish ozone at an alarming rate, by stripping an atom fromthe ozone molecule. A single molecule of chlorine can break apartthousands of molecules of ozone.


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Hydrofluorocarbons (HFCs) are being developed to

replace CFCs and HCFCs, for uses such as vehicle airconditioning. HFCs do not deplete ozone, but they are

strong greenhouse gases. CFCs are even more powerful

contributors to global climate change, though, so HFCsare still the better option until even safer substitutes are

discovered.


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EFFECTS OF OZENE DEPTIONImpact of Ozone Depletion

Crops

Crops

Terrestrial plants vary considerably in their response to

UV-B radiation between species and even between

cultivars of the same species. Plants have several

mechanisms to ameliorate or repair adverse effects from

UV-B radiation, and may acclimate to a certain extent to

increased UV-B radiation levels


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. Impact on Human

Skin Cancer

UVB causes nonmelanoma skin cancer and plays a majorrole in malignant

melanoma developmentNon-melanoma skin cancers mainly include basal cell carcinoma and

squamous cell carcinoma. The mortality rate from non-melanoma skincancer is less than or equal to one percent in areas with good medicalcare


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Cataracts

Human health effects on the eyes include increased

incidence of "snowblindness" and cataracts. The medical

term for snowblindness is photokeratitis, an acuteinflammation of the superficial layers of the eyes. The effect

is dose related and can cause lasting damage in severe cases.

Increased UV radiation will likely increase incidences


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Effects on Marine EcosystemsPhytoplankton form the foundation of aquatic food webs.

Phytoplanktonproductivity is limited to the euphotic zone, the upper layer of

the water column

in which there is sufficient sunlight to support net productivity.

Exposure to solar UVB radiation has been shown to affect

both orientation

mechanisms and motility in phytoplankton, resulting in

reduced survival rates

for these organisms


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Ways to overcome ozonedepletion

Since the banning of CFC in industry (MontrealProtocol, 1989), ozone depletion has mostly stoppedwith some signs that levels are increasing. Scientistsbelieve that ozone will return to its pre-CFC level byabout 2050.


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Ways to Protect the Ozone Layer

Minimize high altitude aircraft flights (oxygenreduction and water vapor deposition)

Minimize rocket flights (water vapor deposition)


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Encourage growth of plants that produceoxygen, discourage deforestation

Decrease / control releases of high

temperature steam / moisture to theatmosphere


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Eliminate production and release of known ozonedepleting chemicals (such as CFCs and HCFCs) where

remotely possible. Subsidize production of safer alternativeswhere possible.

Establish controls to assure that new compounds to be

used in high volume, are surveyed for effect on ozone.


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Actions an Individual Can Take

Ensure technicians repairing your refrigerator or airconditioner recover and recycle the old CFCs so

they are not released into the atmosphere.

Vehicle air conditioning units should regularly be

checked for leaks.


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Ask about converting your car to a substitute

refrigerant if the a/c system needs major repair

Help start a refrigerant recovery and recycling program

in your area if none already exists.


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Replace halon fire extinguishers with alternatives

(e.g. carbon dioxide or foam).

Suggest school activities to increase awareness of

the problem and to initiate local action.


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CONCLUSIONwe are now thoroughly informed about ozone, the phenomena of ozone depletion,the cause, effects and ways to overcome ozone depletion. However, all these matureresearch and informative studies is of no use if we, as part of the human civilizationdo not develop the true attitudes towards ozone depletion and its solution. Countlessresearch can be done and numerous methods of solution regarding ozone depletioncan be conducted, but as long as the human race are not committed, and highspirited enough to solve this global issue, all the brainchild of scientists andenvironmentalists would go down the drain. Therefore, it is of utmost importance ofozone in the future of our planet, and work towards preventing ozone depletionrather than letting the phenomena take place and we find solutions later on. Senseof responsibility towards preserving and maintaining our ozone layer should prevailin all of us and should be stressed so that consistency of handling this issue isensured.

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