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The Process of Ozone DepletionThe ozone depletion process beginswhen CFCs and other ozonedepleting substances (ODS) areemitted into the atmosphere(1).Winds efficiently mix thetroposphere and evenly distributethe gases. CFCs are extremelystable, and they do not dissolve inrain. After a period of severalyears, ODS molecules reach thestratosphere, about 10 kilometersabove the Earth's surface (2).
Strong UV light breaks apart theODS molecule. CFCs, HCFCs,carbon tetrachloride, methylchloroform, and other gasesrelease chlorine atoms, and halons
and methyl bromide release bromine atoms (3). It is these atoms that actually destroy ozone,not the intact ODS molecule. It is estimated that one chlorine atom can destroy over 100,000ozone molecules before it is removed from the stratosphere (4).
Ozone is constantlyproduced and destroyed in anatural cycle, as shown inthe above picture, courtesyof NASA GSFC. However,the overall amount of ozoneis essentially stable. Thisbalance can be thought of asa stream's depth at aparticular location. Althoughindividual water moleculesare moving past theobserver, the total depethremains constant. Similarly,while ozone production anddestruction are balanced,ozone levels remain stable.This was the situation untilthe past several decades.
Large increases in stratospheric chlorine and bromine, however, have upset that balance. In
effect, they have added a siphon downstream, removing ozone faster than natural ozonecreation reactions can keep up. Therefore, ozone levels fall.
Since ozone filters out harmful UVB radiation, less ozone means higher UVB levels at thesurface. The more the depletion, the larger the increase in incoming UVB. UVB has been linkedto skin cancer, cataracts, damage to materials like plastics, and harm to certain crops andmarine organisms. Although some UVB reaches the surface even without ozone depletion, itsharmful effects will increase as a result of this problem.
Ozone layer depletion causing environmental imbalance: CECB
CHHATTISGARH › Raipur
Ozone layer depletion causingenvironmental imbalance: CECBLocation: Raipur, Sept 17, 2014 | Update:2014091709:25:11 | Source: Central Chronicle
Chhattisgarh Environment Conservation Board (CECB)organized intercollege elocution, poster andenvironment quiz at Science College here on Tuesday tomark International Ozone Layer Preservation Day.Addressing the prize distribution ceremony CECBmember secretary Defender Singh urged the students tocreate public awareness for preservation of ozone layer.According to him science students can explain measuresfor preservation of ozone layer to the common public.The ozone layer prevents the harmful ultraviolet Bwaves (UVB) from reaching the earth but due to a largehole in the ozone layer, these harmful ultraviolet rays
are entering into earth’s atmosphere, he said, addingthat in order to prevent depletion of ozone layer it isnecessary to create public awareness. According to himwithout public participation and public awareness itwould be impossible to prevent use of materials causingdepletion of ozone layer.
He said that it was the combined responsibility toprotect ozone layer. College principal Dr Prasademphasized modification in lifestyle by minimizing useof the materials causing harm to ozone layer. Mainspeaker Dr SK Goyal, senior principal scientist and headenvironment division, Niri Nagpur threw light onvarious aspects of environmental conservation. He saidthat depletion of ozone layer became a major cause ofconcern before the world. He said that chemicals ofChlorofluoro category should not be used as they causeharm to ozone layer; rather ozone mixed materialswhich are also ecofriendly should be used. As many as225 students from various colleges took part in thecompetitions. Winners were given away prizes by CECBmember Devendra Singh.
