Environmental scienceLesson 2 of 2 in the course Air pollution

Stratospheric Ozone Depletion: Chemistry, Impacts, and Recovery

5 flashcards · 5 quiz questions · 5 match pairs · 4 fill-in sentences · English

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Summary

This lesson introduces stratospheric ozone, its protective role, and the natural cycle that continually forms and destroys it. Understanding this balance helps explain how human-made chemicals can disrupt the atmosphere.

The ozone layer is a region of the stratosphere containing relatively high concentrations of ozone (O3O_3). Ozone is a form, or allotrope, of oxygen. Ordinary oxygen gas is O2O_2, while an ozone molecule contains three oxygen atoms.

All flashcards

Ozone-depleting substances (ODS)
Manufactured chemicals, including CFCs, HCFCs, and halons, that can release ozone-destroying halogens in the stratosphere.
Catalytic ozone destruction
A sequence of reactions in which a reactive atom destroys ozone and is regenerated, allowing it to repeat the cycle.
Polar stratospheric clouds (PSCs)
Clouds that form in very cold polar stratospheric air and provide surfaces for reactions that activate chlorine.
Dobson unit (DU)
A unit used to report the total amount of ozone in a vertical atmospheric column.
Montreal Protocol
The 1987 international agreement that controls the production and use of many ozone-depleting substances.

Quiz questions

  1. Why can many ozone-depleting substances reach the stratosphere before breaking down?Answer: They are stable and relatively unreactive in the lower atmosphere.
  2. What is the net effect of the simplified chlorine catalytic cycle on ozone and atomic oxygen?Answer: O3+O→2O2O_3 + O \rightarrow 2O_2
  3. What does the Antarctic ozone hole describe?Answer: A marked seasonal reduction in total column ozone.
  4. How can UVB exposure damage DNA in skin cells?Answer: It can cause DNA bases to form dimers.
  5. Which statement about hydrofluorocarbons (HFCs) is accurate?Answer: They do not deplete ozone but may be powerful greenhouse gases.

Based on the Wikipedia article Ozone depletion, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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