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Ozone Depletion Term Paper

Table of Contents Background

Ozone Cycle

Oxygen-Ozone Cycle

Process termination

Trends in Ozone Layer Depletion

Effects of Ozone Depletion on the Environment

Possible Solutions to Ozone Depletion

Conclusion

Works Cited

Background The ozone layer is a blanket of naturally occurring gas that is located in the stratosphere (15 to 50 km above earth) and serves a very important role in blocking the sun’s harmful ultraviolet-B rays from reaching us on earth. However, this protective layer of gases has been undergoing a slow but steady reduction in size. Ozone depletion has been taking place since the 1960s and is now a global phenomenon that requires urgent attention.

Ozone (O3) is a gaseous compound made up of three oxygen atoms and is continually being formed and decomposed in the stratospheric zone. The major cause of this depletion is the continued use of substances containing chlorine and bromine, known as chlorofluorocarbons (CFCs).

Once the CFCs reach the stratosphere, they are broken down into constituent elements and react with the highly reactive ozone molecules, thereby reducing the size of the ozone layer. The U.S. Environmental Protection Agency estimates that a single chlorine atom can decompose more than 100,000 ozone molecules (Newman et al).

While the largest ozone depletion is recorded at the southern and northern hemispheres, the process is taking place everywhere but is minimum in the tropics. This problem has led to increased levels of exposure to UV-B radiation that will continue to have adverse effects on all people living on earth irrespective of their location or economic status.

Individuals with lightly colored skins are more vulnerable to the cancerous effects of UV-B radiation. UV-B radiation also has an impact on plant life, which in turn creates an imbalance in the ecosystem. Scientists have mentioned that depletion of the ozone layer will also reduce fish stocks in lakes, rivers, and seas hence creating a food shortage in areas that heavily depend on fish.

Ozone Cycle Formation of ozone begins when oxygen molecules decompose after absorbing UV light with a wavelength that is less than 240nm in the stratosphere, producing two oxygen atoms. One oxygen atom then reacts with an oxygen molecule to give ozone. The ozone molecule absorbs ultraviolet radiation of wavelength 310 and 200 nm, this decomposes it to oxygen molecule and an oxygen atom.

The oxygen atom then reacts with an oxygen molecule to form ozone. The process is continuous and is known as the ozone-oxygen cycle. The cycle stops when an oxygen atom reacts with ozone molecule to give two oxygen molecules, i.e.

Get your 100% original paper on any topic done in as little as 3 hours Learn More Oxygen-Ozone Cycle O2 -UV radiation ( 20

O O2 -> O3

O3 -UV radiation (310-200 nm)->O O2

Process termination O O3 ->2O2

Generally, the level of ozone in the stratosphere is controlled by the balance between the photochemical production of oxygen atoms and the recombination reaction.

Destruction of the ozone occurs when free radicals reach the stratosphere, these radicals include the hydroxyl radical, nitric oxide radical, chlorine radical and bromine radical. Hydroxyl and nitric acid radicals reach the atmosphere through natural ways, however, chlorine and bromine radicals are due to man’s activities and are found in certain stable compounds, especially CFCs (McFarland, pp. 1207).

CFCs can reach the atmosphere without decomposing into their constituent elements since they are stable and non-reactive. When CFCs reach the stratosphere, they undergo photochemical decomposition to release chlorine or bromine atom, i.e.

We will write a custom Term Paper on Ozone Depletion specifically for you! Get your first paper with 15% OFF Learn More CFCl3 -> CFCl2 Cl

The liberated chlorine and/ or bromine atoms destroy ozone molecules through a series of catalytic reactions (Solomon et al, pp. 412). In an elementary example of this reaction, a chlorine atom reacts with ozone molecule forming chlorine monoxide, ClO, i.e.

Cl O3 -> ClO O2

The chlorine monoxide is unstable and can readily react with another ozone molecule to give two oxygen molecules as shown below:

ClO O3 -> Cl 2O2

This reaction reduces the number of ozone molecules in the stratosohere.

A single chlorine atom would continuously destroy ozone molecules for up to two years, however, other reactions in the stratosphere remove these elements. Bromine is more destructive than chlorine. Both of these elements are present in the stratosphere and cause considerable damage to the ozone layer. A single chlorine atom is able to destroy nearly 100,000 ozone molecules, when we consider the amount of CFCs released into the atmosphere annually, the damage done to the ozone layer becomes apparent (Storlaski et al, pp. 1015).

Trends in Ozone Layer Depletion Studies of the ozone layer have been undertaken since the mid 20 the century, however, changes in its size became apparent between 1960 and 1970 when it was observed that it had reduced by 23 per cent between this duration. In 1985, the ozone hole was first observed in the Antarctic. By 1986, three models had been postulated to explain ozone depletion:

Not sure if you can write a paper on Ozone Depletion by yourself? We can help you for only $16.05 $11/page Learn More Solar cycle model- regular increases in the quantity of nitrogen oxides in the lower Antarctic stratosphere is due to changes in solar radiation;

Dynamical model- an alteration in the circulation pattern from downwelling of air with a high abundance of ozone from the upper stratosphere to upwelling of air deficient of ozone from the troposphere; and

Halogen model- a number of variant theories centering on the catalytic destruction of ozone layer because of CFCs and halons (Storlaski et al, pp. 1015).

A study was undertaken by McMurdo in 1986 that showed that the concentrations of nitrogen oxides were remarkably low, hence disapproved the solar cycle model. He also observed that the levels of long-lived tracers were due to complex reactions and was unlikely to occur, and that the high levels of chlorine in the stratosphere was the most probable cause of ozone depletion (Storlaski et al, pp. 1015).

The Montreal Protocol was signed in 1987, although the origin of the ozone hole was not well understood, the protocol recognized that the stratosphere had been disturbed. It was observed that the levels of chlorine in the atmosphere had increased by about 5% and that there had been a considerable loss in ozone every October in the Antarctica (Newman et al). The Montreal Protocol was signed by 31 countries and was aimed at cutting CFC emissions as shown below:

Fig. 1: Montreal Protocol Cap

The pact has been ratified by 197 nations to date and aims at reducing CFC emissions gradually so that no emissions will be made by 2030.Unfortunately, only a few countries have implemented the emission control mechanisms.

Advances in scientific methods improved man’s understanding of the ozone layer from 1987 -92. This enabled scientists to re-assess present and early trends in the stratospheric ozone.

Studies undertaken in Punta Arenas, Chile, in 1987 that involved making flights above the Antarctica gave a good understanding of the role of CFCs in ozone depletion (Farman et al, pp. 209). Chlorine and low concentrations of bromine were detected in this area, the study also found out that the level ClO was considerably high.

Other observations such as the presence of bromide radical (BrO), low concentrations of water vapor, nitrogen oxides, and nitrous oxide, and polar stratospheric clouds confirmed that the ozone hole was formed due to the catalytic destruction of ozone by chlorine radicals (Weatherhead

Boeing Company Completion of Production and Modification Essay (Critical Writing)

Nursing Assignment Help Completion of Production and Subsequent Modification As compared to doing modification during production to all the thirty planes that were under production, it is advisable for the Boeing Company to complete the assembly process first then do the modifications later.

One primary reason why the company should implement the option is because this method will guarantee assembly or production of safer airplanes. In engineering endeavour, safety should the primary fact factor that any manufacturing and assembling company should consider, airplanes being transportation machines that fly over great heights and long distances; hence, the need to ensure that they are up to standard.

Failure to take this seriously may put at risk people’s lives, which may make the company to incur numerous liabilities in case of an accident that may result due to a manufacturing error. Under this method, the flaps, ailerons, landing gear, hydraulics, and other aeroplane system are supposed to undergo thorough testing to ascertain their functionality, a case that is contrary if the modifications are to be made during the production process.

As a result of this, likelihoods of the testing procedures changing are high; hence, the nature of high safety risks associated with this method, as this dictates that testing must be done after the two-person cockpit has been fully put in place. Testing before installing the two-person cockpit is very important, as it will facilitate correcting of any assembly problems that may be disguised or not discovered if the production process is started afresh.

In addition to levels of safety that are associated with the this method, this method is also cost-effective, because of the lesser labour hours that it requires, as compared to running the modification and production processes concurrently. In any project it is important to minimise the costs associated with the manufacturing and acquisition of any product to increase its net value, not only to its manufacturers, but also to its purchasers.

A project’s value must have both a business value and make sense in terms of meeting the financial budget requirements, because of huge sums of funds that are required in the commercial aircraft manufacturing industry. Therefore, considering that these thirty planes had been assembled to some level, it would be more expensive to do the modifications along the production process, as this will increase the scrap costs.

On the other hand, to reduce the risk of exceeding the time scheduled for the project, Boeing should take this option as will guarantee that the company will meet all the production deadlines; hence, minimise the likelihoods of incurring losses associated with fines from its customers. This is the case primary because, the airline industry is a fast moving industry and because every firm in the industry wants to meet its strategic goals; any delays in delivery of the ordered aeroplanes will mean a reduction in such companies.

Get your 100% original paper on any topic done in as little as 3 hours Learn More As compared to budget overruns, bearing the liability of late product delivery is more expensive; hence, the need of the company to take an approach that will ensure it minimises the likelihoods of such liabilities arising. Further, although this method may compromise the initial design of the airplanes, because of its associated cockpit configuration risks, this is something that the Boeing Company can minimise by using a careful assembly process, using required management controls.

Finally, this approach is better as compared to running the modification and production process concurrently, because it does not require any disruption of the original production plan. This is very crucial in maintaining the learning curves, as this method will reduce the number of experts that are required to facilitate completion of the thirty aeroplanes.

Maintaining a learning curve is a primary deliverable not only to stakeholders, but also to assemblers, because of the significance of this parties getting acquainted with the required levels of knowledge about the working of the entire aeroplane system. In addition maintaining the learning curve will guarantee an increased rate of production and meeting of all production time schedules.

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