Ozone and Ozone Depletion Essay ⋆ Environment Essay Examples ⋆ EssayEmpire

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Ozone (O3) is a form of oxygen that forms naturally in the atmosphere and also as a result of some electrical activity. It has a characteristic odor and is an irritating and toxic gas at even low concentrations. Ozone plays a vital role in shielding the surface of the earth from damaging ultraviolet radiation. In recent years, ozone has become increasingly depleted as a result of the emission of man-made chemicals into the air. Fears of widespread damage to the ozone layer-which some believe have led to such diseases as skin cancer-have prompted concerted action to repair the problem.

Ozone is present in the stratosphere, which is a layer in the atmosphere from 10 to 50 kilometers above the surface of the earth. This is the height at which airplanes are flown. Ozone in the stratosphere acts as the primary shield against ultraviolet (UV) radiation. Without ozone, severe cellular damage to nearly all forms of life on earth would result. In humans, UV radiation darkens the skin and destroys cells depending on the position within the UV spectrum it occupies. UV radiation is defined as being between 40 and 400 nm, which occupies the space between X-rays and visible light. Excessive UV radiation can lead to the formation of skin cancers and cataracts, in addition to sunburn (erythema).

By passing an electrical discharge through a stream of normal, diatomic oxygen (02), ozone may be manufactured. It has a number of industrial applications, including chemical oxidation, organic syntheses, and water disinfection. It can decolorize and deodorize a number of substances, which is useful for consumer goods. Depending on the presence of certain other catalysts, ozone may rapidly decompose at everyday temperatures or at the boiling point of water and above. This and the toxicity of the gas mean that it must be handled with some care.

The amount of ozone in the stratosphere has historically been constant, although processes of formation and destruction of individual ozone molecules is continuous. The total amount has varied within predictable and fairly well-established levels, depending on changes in seasonality and latitude and on the changing prevalence of sunspots. However, it has become increasingly obvious in recent years that the depletion of atmospheric levels of ozone has exceeded all known precedent and may have reached a level beyond which natural restorative processes will replenish it. The reason for this is due to the release of chlorofluorocarbon gases (CFCs) into the atmosphere. CFCs have been used in consumer goods and industrial applications since their development some 50 years ago. They are customarily low in toxicity, nonflammable, and stable and of great value as refrigerants, solvents, and fire retardation agents, among other uses.

Unfortunately, it is the stability of these compounds that causes the problem as it permits the chlorine-bearing compounds to be released into the atmosphere when the substances begin to deteriorate.

Although chlorine has been extensively used in human society in such applications as hygiene in swimming pools, this chlorine does not reach the upper atmosphere because it quickly reacts with water in the atmosphere and falls in the form of rain. CFCs are instead driven through the atmosphere by wind action and may pass into the stratosphere. Intense UV radiation can cause the CFC molecules to break down and release chlorine into the upper atmosphere. The chlorine acts as an extremely effective destroyer of ozone; as many as 100,000 molecules of ozone can be destroyed by a single chlorine molecule.

Prevailing winds and usage patterns determine that the flow of CFCs are concentrated more in some areas rather than in others. In 1985, a group of scientists led by Joe Farman, Brian Gardiner, and Jonathan Shanklin published research showing that a hole in the ozone layer had been detected over Antarctica. Subsequent research has shown that the hole appears on an annual basis and has been growing. At its greatest extent, the hole over Antarctica grew to a size that was the equivalent of more than three times the land area of the United States. Clearly, if the hole were to reach heavily populated areas, its impact would be disastrous.

The discovery of the hole led to the creation of one of the first global environmental treaties, the Montreal Protocol of 1987, which bans the production of CFCs. Gradually, the use of these chemicals has been phased out with old kitchen appliances such as refrigerators. Determined efforts have led scientists to predict that the hole is in the process of being repaired and could be fully restored by as early as 2050, assuming current trends continue. Despite measures to ban CFCs, the amount of ozone loss is still reaching record levels. Some 40m tons of ozone have been lost in 2005-06, showing that the ozone layer hole will reach an unprecedented size each year until 2018, according to the most recent data.

At that point, its overall size can be expected to decrease in size and significance. As the Montreal Protocol demonstrates, it is possible for determined human activity-cooperating together and coordinated at the state level-to tackle important, large-scale environmental problems. This may be seen as symbolic of the possibilities of the fight to restore the earth from the dangers of global climate change.

Bibliography:

F. Dentener et , “The Global Atmospheric Environment for the Next Generation,” Environmental Science and Technology (v.40/11, 2006);
Environmental Protection Agency, www.epa.gov;
C. Farman et al., “Large Losses of Total Ozone in Antarctica Reveal Seasonal ClOx/NOx Interaction,” Nature (May 16, 1985);
Tim Flannery, The Weather Makers: How Man Is Changing the Climate and What It Means for Life on Earth (Atlantic Monthly Press, 2006);
Elizabeth Kolbert, Field Notes from a Catastrophe (Bloomsbury, 2006);