The Stratospheric Ozone Layer and Ground Level - Essay Example

Earth Systems 2. Explain the difference between ground- level and stratospheric ozone; why has one a beneficial and the other a detrimental role in the atmosphere? In the early phase of the earth’s history, life could only survive in the oceans because the deadly ultraviolet rays of the sun precluded the growth of life on the earth’s surface. These UV rays could not, however, penetrate water, hence, life flourished in the oceans until ozone started forming from oxygen. Ozone, which has a chemical symbol of O3, is a colorless and unstable gas made up of three atoms of oxygen (Butz 376). It occurs in two layers of the earth: the stratospheric layer, and; the tropospheric layer or the ground-level layer. Presently posing a problem to the environment is the fact that the concentration of ozone in the ground-level is increasing while ozone in the stratospheric level is diminishing (Wright 774). This is a global environmental predicament because the stratospheric ozone has beneficial use while ground-level ozone produces detrimental effects. The Stratospheric Ozone Layer The stratospheric ozone layer was discovered sometime in the 1870s when scientists, led by G.M Dobson, observed the diminished amount of UV rays as they reach the earth’s surface, eventually attributing this phenomenon to ozone. By deduction, they concluded that the concentration of ozone in the upper atmosphere is higher than that nearer to the ground. A century later, it was discovered that certain elements could pose threat to this layer. When the US was planning to build supersonic transport planes (SST), studies revealed that the nitrogen oxide they would emit in the stratosphere layer, where they would be expected fly most of the time at a speed three times to that of sound and at an altitude of 12.4 miles, could destroy ozone (Konvicka 272). In the stratosphere, ozone is formed through a process called photolysis, when oxygen in the atmosphere is bombarded by solar UV radiation. This causes the two atoms of oxygen to split apart and merge with the atoms of other oxygen. The ozone gases then bond to form the ozone layer. This layer of ozone forms between 12 and 15 miles above the earth and protects it as well as life on it from dangerous UV solar radiation (Butz 376; Onursal et al 19). Ozone formation and destruction in the atmosphere occurs continuously and cyclically every time the UV rays of the sun act upon them, causing the breakdown of the gas and converting the resulting energy into heat. The heat raises the temperature at higher altitudes blocking the entry of the ultraviolet rays to the lower levels of the atmosphere. The split oxygen atoms then re-bond with the atoms of other oxygen to form new ozone. This continuous and recurring destruction and rebirth of ozone is said to have reached a state of state equilibrium, that is, “the amount of ozone gas that is destroyed by ultraviolet radiation equals the amount that is reformed” (Butz 376). The stratospheric ozone layer protects earth’s surface and life on it from the harmful solar UV rays because it absorbs most of the rays, allowing only a tolerable amount of to reach the earth’s surface. Thus, it averts the likelihood of skin cancer, cataracts in humans, and prevents the demise of algae and certain bacteria useful to the formation of life. Algae produce oxygen and helps in the breakdown of carbon dioxide while bacteria are useful in crop production. The stratospheric ozone layer also plays a role in the earth’s geothermal balance, a determinant in the global climactic system stability. A diminished stratospheric ozone layer will spell disaster because in the first instance, danger to the earth’s biosphere is likely and in the second, greenhouse effect is increased (Konvicka 261). The protective barrier that the stratospheric ozone layer offers between the sun and earth is the reason why ozone depletion is currently posing a threat to earth and life on earth. Ozone depletion is the diminishing of the ozone content in the stratosphere mainly due to the presence of anthropogenic-emitted gases that interrupts its natural chemical formation. Some of these gases are the chlorofluorocarbons (CFCs) emitted by refrigerants, aerosol sprays and electrical parts which are not harmful at low atmospheric levels but become dangerous as they rise up to higher levels (Butz 378). The Ground-Level Ozone Layer In the tropospheric or ground-level layer, ozone is formed by the action of two kinds of pollutants that mix in the air while there is sunlight: volatile organic compounds (VOCs hereafter) and nitrogen oxides. VOCs are emitted by motor vehicles, gas stations, chemical plants, and other industrial facilities like solvents and chemicals. On the other hand, nitrogen oxides are products of motor vehicles, power plants and fuel-burning systems (Hedges 3-1). Since VCOs and NO can be dispersed by the winds, these pollutants can affect areas where wind currents bring them. Ozone is not the only substance produced during the reaction of pollutants with oxygen in the presence of sunlight and high temperature but also small amounts of organic and inorganic compounds like peroxyacetylnitrate and nitric acid. Concentration of tropospheric-level ozone is dependent on the concentration of the pollutants in a given area, solar radiation intensity and thermal inversions. Thermal inversion refers to the settling of warm air over cooler air near the ground level, preventing the cooler air from dispersing and scattering the pollutants (Onursal et al 19). The ill-health effects of the ground-level ozone, which forms a large part of what is visibly as smog, have been well documented. In addition, air pollution can also negatively affect vegetation, materials and visibility (Wright 775). Ozone pollution is known to affect the lungs and cause various painful respiratory illnesses for several hours after exposure to it. It makes breathing doubly hard because it affects the volume and speed at which human lungs can take in oxygen and exhale it. Needless to say, ozone pollution aggravates respiratory ailments like asthma, emphysema and bronchitis. It can even damage cell linings of the lungs and although they regenerate in a few days to replace damaged cell linings, a repetition of the same process over and over can permanently alter the lungs negatively. These ill-effects of the ground-level ozone layer are particularly worse during summer when all the elements of ozone formation are their most intense and when air masses are stagnant (Hedges 3-2). Conclusion The main difference between stratospheric ozone and ground level ozone is one is good and the other is bad. Stratospheric ozone is good because it protects earth and life on earth from the harmful effects of the UV rays of the sun, through absorption, which can cause skin cancer and all other ailments in humans as well as affect the production of certain substances important to the formation and maintenance of life on earth and the biosphere, in general. Its gradual depletion is, therefore, viewed with apprehension by scientists and environmentalists. On the other hand, the formation of ground level ozone is bad because it engenders negative health problems and issues. Ground-level ozone is synonymous with air pollution, a term that implies ailments, primarily related to respiratory ones, and especially harmful to people already suffering from chronic lung-related ailments. Works Cited Butz, Stephen. Science of Earth Systems. Cengage Learning, 2002. Hedges, Scott. Planning and Implementing a Real-Time Air Pollution Monitoring and Outreach Program for Your Community: The Airbeat Project of Roxbury, Massachusetts. DIANE Publishing, 2002. Konvicka, Tom. Teachers Weather Sourcebook. Libraries Unlimited, 1999. Onursal, Bekir & Gautam, Surhid. Vehicular Air Pollution: Experiences from Seven Latin American Urban Centers. World Bank Publications, 1997 Wright, John. The New York Times Almanac 2002. Routledge, 2001. Read More