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Ozone hole response

The catalyzed decomposition of ozone is known to be responsible for the ozone hole (Figure A) that develops in Antarctica each year in September and October, at the end of winter in the Southern Hemisphere. No ozone is generated during the long, dark Antarctic winter. Meanwhile, a heterogeneous reaction occurring on clouds of ice... [Pg.311]

The process responsible for the "ozone hole over Antarctica is thought to be similar, though it may be heterogeneous, taking place on ice particles.58... [Pg.135]

Functional roles treated above are strictly organismal responses to biotic stresses. The use of chemical means to address physical stresses is largely nonexistent. A notable exception to this is the response many organisms make to harmful ultraviolet (UV) radiation. Sunscreens are small organic molecules which absorb UV radiation so that damage to DNA via cross-linking219 225 is prevented. Production of micosporin-like amino acids (MAA) appears to be widespread in shallow-water Antarctic marine invertebrates and macroalgae,223,224 which may be particularly adaptive at present because of the Antarctic ozone hole. [Pg.288]

Chlorofluorocarbons, such as CF3C1, catalyze this reaction and are responsible for the formation of the ozone hole. The decomposition is a chain reaction involving chlorine atoms as the chain-carrying species. Suggest a mechanism for this reaction. [Pg.953]

These catalytic cycles are largely responsible for the depletion of ozone. One chlorine atom may destroy more than 100,000 ozone molecules before it is transformed into a non-reactive species. Despite the substantial reduction of chlorine and bromine compounds released into the atmosphere as a result of the Montreal Protocol, this has not shown any significant impact on the reduction of the size of the ozone hole. If such a trend continues, it may still take some half a century for the recovery of ozone to the levels it had prior to 1984. [Pg.178]

When the ozone hole was reported in 1985, scientists had made measurements of CFC levels in the stratosphere that supported the hypothesis that CFCs could be responsible for the depletion of ozone. The pure research done only for the sake of knowledge became applied research. Applied research is research undertaken to solve a specific problem. Scientists continue to monitor the amount of CFCs in the atmosphere and the annual changes in the amount of ozone in the stratosphere. Applied research also is being done to find replacement chemicals for the CFCs that are now banned. Read the Chemistry and Society feature at the end of this chapter to learn about research into the human genome. What type of research does it describe ... [Pg.14]

By September 1992, this ozone hole was nearly three times the area of the United States. In December 1994, three years of data from NASA s Upper Atmosphere Research Satellite (UARS) provided conclusive evidence that CECs are primarily responsible for this destruction of the ozone layer. Considerable thinning of the ozone layer in the Northern Hemisphere has also been observed. [Pg.695]

Numerical models have been used to predict the potential ozone depletion in response to the emission of halocarbons, based on different plausible scenarios. All of these models indicate that the time required for the middle atmosphere to respond to surface emissions of these halocarbons is very long (several decades). In particular, even with the measures taken to reduce or phase-out the emissions of the CFCs and other halocarbons, it is expected that the Antarctic ozone hole will be observed each spring (September-October) at least until the year 2040. It should also be noted that the halocarbons are active in the infrared, and contribute to the greenhouse effect. [Pg.9]

What are the mechanisms responsible for the spectacular ozone decreases in the Antarctic ozone hole ... [Pg.164]

Chapter 7 is a new chapter on the relationship between GFGs and the ozone hole, expanded from the four pages in the previous edition. The mechanisms by which oxygen and ozone protect us are discussed in the context of the Chapman Cycle. Scientific responses to the issue and the replacement of CFCs are considered. There is also discussion addressing the relationship between UV exposure and skin cancer. [Pg.606]

Earlier, in Chapter 6, we discussed the catalytic cycle involving chlorine free radicals generated by the effect of ultraviolet radiation on chlorofluorocarbons (CFCs). This cycle results in the phenomenon of ozone depletion and the consequent polar ozone holes . CFCs are not the only compounds that cause this depletion. Nitrogen oxides (NO, ) are also responsible. [Pg.511]

Research has shown that heterogeneous catalysis is most likely responsible for the annual formation of an ozone hole over Antarctica. After the discovery of the Antarctic ozone hole in 1985, scientists wondered why there was such a dramatic drop in ozone over Antarctica but not over the rest of the planet. After aU, the chlorine from chlorofluorocar-bons that catalyzes ozone destruction is evenly distributed throughout the entire atmosphere. [Pg.629]


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