OZONE DEPLETION: DANGER FOR ATMOSPHERE
The Sun emits radiation over a broad range of wavelengths to which human eye respond in the region from approximately 400nm to 70 nm. The ranges can be divided into three categories: UVA (Ultra violet): 320-400nm). DVB (280-320 nm) partially absorbed by Ozone. UVC (200-280 nm) completely absorbed by Ozone. The maximum concentration (about 0.5 ppm) occurs between the altitude of 20 to 35 km. and the layer at this level is called ozone layer. The presence of ozone is an essential necessity for life on Earth.
Stratospheric ozone layer absorbs dangerous UVB rays of the sun and this protects the earth surface from these high-energy radiations. Over the past few decades 03 layer is thinning out because of manmade pollutants, which catalyze the dissociation of 03 at a very fast rate. Major pollutants responsible for depletion of Ozone are chloroflourocarbons (CPCs) nitrogen oxides, hydrocarbons and oxides of chlorine and bromine.
Increased ultraviolet radiation would retard photosynthesis in plants. Moreover it would increase earths mean temperature which would have disastrous consequence of flooding submerging many low lying islands. Recently it has been found that the ultraviolet radiation degrades polymers used in paints and building materials.
Most ozone are created and destroyed in the stratosphere. The high energy ultraviolet rays break some of the oxygen molecules into oxygen atoms. These oxygen atoms recombine with the oxygen molecules to form a three atom molecule of oxygen called ozone. But ozone being highly reactive combines with other compound present in the stratosphere. This is how ozones are created and destroyed in a balanced way by the sun’s radiation. However this balance is disturbed when chlorine atoms, release from the earth, react with the ozone molecule and this reduces ozone population in the atmosphere. In this process even more ozone molecules are destroyed than created.
The Chlorine atoms, released from manmade materials such as CFC or chloro-flouro Carbons enter the atmosphere (which takes 50 to 100 years) and break down bonds holding three atoms of ozone. The chlorine is converted into chlorine monoxide and oxygen is released. This loss of ozone molecules is known as the depletion of the ozone layers. Needless to say, the loss of ozone molecules reduces the ability of the stratosphere to filter out harmful ultraviolet rays.
Ozone depletion happens rapidly near the poles in spring because the prevailing low temperature of the stratosphere makes the ozone more vulnerable to reaction with other substances.
Normally the nitro-oxide destroys the chlorine monoxide and hence prevents the ozone depletion. But the story is quite different in the Polar Regions. There the nitrous oxide freezes to form ice clouds and chlorine monoxides left tree to destroy the ozone molecules.
Montreal Protocol considering the monumental damages ozone depletion does, the world community is taking steps to control the ozone depletion. The Montreal Protocol adopted in 1987 and strengthened in 1990, called for phasing out CFCs and other ozone depleting substances by2000, established rules governing international trade in ODS and their products. Since developing countries lack the financial and technological means to replace CFCs or other ODS such as haloes and Carbon tetra oxide. They have been given a grace period of 10 year. That is how they are required to phase out CFCs by 2010.
The protocol called for a multilateral tuna to assist the developing countries in the transfer of technology that eliminates CFC or ODS. India is expected to get about $ 19 billion under the protocol for subsiding ODS India on its part has stopped the trade of eight ODSs to these countries which are not signatories to the protocol. But a suitable mechanism to facilitate the transfer of technology to the developing countries is still eluding.
Indian Law on Ozone Protection—India has in response to Montreal Protocol, notified Ozone Depleting Substance (Regulations and Controls) Rules in phasing out various ODS or Ozone Depleting Substances besides regulating their production and trade under the rules, the use of CFCs except for medical purposes was prohibited after January 1, 2003. The rules also calls for compulsory registrations of ODS producers, traders and stockiest etc.
India’s per capita consumption of ODS now at less than 3 gmis through well below permissive level of300 gm under the Montreal Protocol. Euro-Emission Norms
Euro I and II names are given to emission norms for new petrol and diesel driven vehicles. In this extent of emission of carbon monoxide (CO) hydrocarbon nitrogen oxide (NOX) and particulate matter have been specified in terms of gram/km. All car manufacturers wanting to sell their cars in the National Capital Region (NCR) will have to meet these norms.
Pollution Petrol Vehicle Diesel Vehicle
Co 2.2 3.16 HC 1.131.13 NOX 1.131.13 Particulate NIL 0.14 Euro II
Pollutant Petrol Vehicle Diesel Vehicle
CO 2.20 1.0 HC 0.50 0.90 NOX 0.50 0.70-0.90 Particulate Matter Nil 0.80 Melting of Arctic Ice
The Arctic Ice layer is melting faster than expected and could disappear entirely by the end of the century. This meltdown will endanger not only Polar Species, but also pave the way for new economic opportunities. According to the Norwegian geophysicists, the thickness of the ice-cap is decreasing by almost 15 percent each decade because of global warming. A total disappearance of ice would have dramatic consequences on local fauna, particularly, polar hears, seals and walruses.
However from the economic point of view, melting of ice could result in a future waterway between Europe and Asia via the Arctic Ocean and lead to the discovery of new oil files and fishing zones, which are currently buried under the ice. According to the researchers the ice melts due to the warming of both the waters of the North Atlantic and air temperatures in the region. Numerous studies have indicated that the frozen sea over the North Pole is rapidly melting.