The Ozone Layer Ozone Depletion

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1 The Ozone Layer Ozone Depletion

2 Schedule 1. Ozone Layer & Depletion Let s learn about it! 2. Think, Pair, Share Activity CFC s and you 3. Graphing Activity

3 Ozone Depletion The ozone layer is a belt of naturally occurring ozone gas that sits 9.3 to 18.6 miles (15 to 30 kilometers) above Earth and serves as a shield from the harmful ultraviolet B radiation emitted by the sun.

4 What is ozone? Ozone is a highly reactive molecule that contains three oxygen atoms. It is constantly being formed and broken down in the high atmosphere, 6.2 to 31 miles (10 to 50 kilometers) above Earth, in the region called the stratosphere ***REMINDER - The stratosphere is the second layer of the Earth's atmosphere. The ozone layer absorbs harmful rays from the Sun here.

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6 What are the effects of ozone depletion? The ozone layer is deteriorating due to the release of pollution containing the chemicals chlorine and bromine. Such deterioration allows large amounts of ultraviolet B rays to reach Earth, which can cause skin cancer and cataracts in humans and harm animals as well.

7 How the ozone layer protects us

8 Illnesses in humans caused by overexposure to UV rays Higher levels of UV radiation lead to increased rates of health hazards such as cataracts and skin cancer. UV radiation can lead to suppression of the immune system in humans and other animals. UV radiation leads to increased risk in Skin Cancer UV radiation causes damage to plants by affecting photosynthesis and growth.

9 Effects on the Environment Radiation also affects phytoplankton, the almost microscopic plant organisms in the oceans. These phytoplankton produce a great deal of Earth s oxygen and are the basis of all food chains in the oceans and are vital to the health of all life on Earth. Biologists fear that reductions in phytoplankton populations will in turn lower the populations of other animals. Researchers also have documented changes in the reproductive rates of young fish, shrimp, and crabs as well as frogs and salamanders exposed to excess ultraviolet B

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11 Human activity and the ozone layer Chlorofluorocarbons (CFCs), are chemicals found mainly in spray aerosols cans. When CFCs reach the upper atmosphere, they are exposed to ultraviolet rays, which causes them to break down into substances that include chlorine. The chlorine reacts with the oxygen atoms in ozone and rips apart the ozone molecule.

12 Aerosol Cans-One atom of chlorine can destroy more than a hundred thousand ozone molecules, according to the U.S. Environmental Protection Agency. Ozone Layer Depletion

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14 Think, Pair, Share Take a moment now to THINK of the emissions that you may release into the atmosphere that may affect our Ozone. What is causing this and can you change to make a difference? PAIR up with a partner or someone near you and compare your answers with theirs. Now its is time to SHARE some of your answers with the rest of the class!

15 Impact on the Arctic The ozone layer above the Antarctic has been particularly impacted by pollution since the mid-1980s This region s low temperatures speed up the conversion of CFCs to chlorine. In the southern spring and summer, when the sun shines for long periods of the day, chlorine reacts with ultraviolet rays, destroying ozone on a massive scale, up to 65 percent. This is what some people erroneously refer to as the "ozone hole." In other regions, the ozone layer has deteriorated by about 20 percent.

16 More Developed Countries About 90 percent of CFCs currently in the atmosphere were emitted by industrialized countries in the Northern Hemisphere, including the United States and Europe. These countries banned CFCs by 1996, and the amount of chlorine in the atmosphere is falling now. But scientists estimate it will take another 50 years for chlorine levels to return to their natural levels.

17 Graphing Activity Turn to page 112 of your textbook and look at the Statistical Analysis question #4 and figure 5.15 and You are to complete questions 4 a) by drawing one multiline graph for figure Choose three (3) different ozone depleting gases and graph them on grid paper. You are to complete the following for figure 5.16 graphing world production of ozone-depleting chemical compounds.

18 For your graph: Y-Axis Ozone Depleting Gases (Parts per Trillion) VERTICLE This represents the amount along the side of the graph start it at 0 at the bottom and increase X-Axis Years HORIZONTAL This represents the different years along the bottom of the graph that data was collected. Start at 1978 and continue until Plot your markings as dots on the graph and then connect the line to complete the line graph.

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