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Natural Resources, Pollution, and Human Impact 29 Acid Rain Seven friends were talking about acid rain. They each had different ideas about acid rain. This is what they said: Lynda: I’ve heard that we have acid rain because of the hole in the ozone layer. Sam: All rain is acidic. This is normal. Hank: The rain didn’t used to be acidic. Global warming has made it acidic. Otto: Pollutants evaporate from lakes, rivers, and ground spills and come down again as acid rain. Elisa : Acid rain is caused when normal rain combines with things in the air that come from pollution. Imani: Acid rain used to be a big problem. Due to regulations and laws, there is no more acid rain. Paolo: Carbon monoxide from automobile exhaust combines with rain to make acid rain. Which student do you agree with the most? ______________ Explain your thinking. _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ Uncovering Student Ideas in Ear th and Environmental Science Copyright © 2016 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions. TO PURCHASE THIS BOOK, please visit www.nsta.org/store/product_detail.aspx?id=10.2505/9781938946479 151 29 Natural Resources, Pollution, and Human Impact Acid Rain Teacher Notes Purpose The purpose of this assessment probe is to elicit students’ ideas about pollution. The probe is designed to uncover commonly held ideas about acid rain. Type of Probe Friendly talk Related Concepts Acid rain, pollution Explanation The best answer is Elisa’s: “Acid rain is caused when normal rain combines with things in the air that come from pollution.” Oxides of sulfur and nitrogen are produced from industrial pollution, such as the burning of coal. These substances rise into the atmosphere, where they mix and react with water to form a more acidic pollutant, known as acid rain. Normal rain is slightly acidic, with a pH of about 5.7. The rain that falls on land 152 contains some dissolved carbon dioxide from the surrounding air. This causes rainwater to be slightly acidic because of the carbonic acid that is formed when pure water (pH 7) mixes with carbon dioxide. This process is beneficial in breaking down minerals found in the soil to make them accessible to plants for nutrient absorption. Acid rain resulting from reaction with pollutants has a pH of about 4. The lower the pH number, the more acidic the rain is. Acid rain used to be a bigger problem than it is today. The worst effects in the United States were seen in the eastern states, which have more concentrated industrialization. In those areas, acid rain killed trees and harmed lakes and streams. Some lakes were declared biologically dead. The pH of rain in the northeast in the 1950s and 1960s was commonly as low as 4.0–4.5, with some storms delivering rain with a pH as low as 3.0. Compare that with the pH of vinegar, which is 2.4. Pollutants from the factory smokestacks in the Midwest are carried by the wind to the Northeast and N a t i o n a l S c i e n c e Te a c h e r s A s s o c i a t i o n Copyright © 2016 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions. TO PURCHASE THIS BOOK, please visit www.nsta.org/store/product_detail.aspx?id=10.2505/9781938946479 Natural Resources, Pollution, and Human Impact exacerbate the problem. In Europe, acid rain had a devastating effect on marble statues and buildings. In the United States, the Clean Air Act of 1970 and the Acid Rain Program, established under Title IV of the 1990 Clean Air Act Amendments, aggressively worked to reduce emissions from power plants. The efforts resulted in the highly acidic rains in urban areas dropping to an average of pH 4.8 today. Unfortunately, we still experience harmful acidic rains and need more work to bring those pH levels down to a range that does not damage natural systems or the built environment, including marble statues and stone that reacts with acid. Administering the Probe This probe is best used with students in grades 6–12 who have some knowledge of the basic chemistry involved. Related Core Ideas in Benchmarks for Science Literacy (AAAS 2009) 6–8 The Earth The benefits of Earth’s resources—such as fresh water, air, soil, and trees—can be reduced by deliberately or inadvertently polluting them. The atmosphere, the oceans, and the land have a limited capacity to absorb and recycle waste materials. In addition, some materials take a long time to degrade. Therefore, cleaning up polluted air, water, or soil can be difficult and costly. 9–12 The Earth Although the Earth has a great capacity to absorb and recycle materials naturally, ecosystems have only a finite capacity to withstand change without experiencing major ecological alterations that may also have adverse effects on human activities. 29 Related Core Ideas in A Framework for K–12 Science Education (NRC 2012) 6 –8 ESS3.C: Human Impacts on Earth Systems Human activities have significantly altered the biosphere, sometimes damaging or destroying natural habitats and causing the extinction of other species. But changes to Earth’s environments can have different impacts (negative and positive) for different living things. 9–12 ESS3.C: Human Impacts on Earth Systems Scientists and engineers can make major contributions by developing technologies that produce less pollution and waste and that preclude ecosystem degradation. Related Research Khalid (2001) found that elementary preservice teachers thought that pollutants evaporate and come down as acid rain. He also found a common misconception that the students thought acids have a higher pH than bases. Darcin (2010) found that 76% of the students sampled erroneously held the idea that carbon monoxide is responsible for acid rain. More than half (55%) saw carbon dioxide as a factor of more acid rain. Nearly half of the students (48%) thought that chlorofluorocarbons cause acid rain. Researchers have found that students of all ages are aware of environmentally “friendly” and “unfriendly” actions, and they know about a range of environmental problems. However, they tend not to link causes with their consequences and may have a tendency to imagine that all environmentally friendly actions help to solve all environmental problems (Driver et al. 1994). Uncovering Student Ideas in Ear th and Environmental Science Copyright © 2016 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions. TO PURCHASE THIS BOOK, please visit www.nsta.org/store/product_detail.aspx?id=10.2505/9781938946479 153 29 Natural Resources, Pollution, and Human Impact Suggestions for Instruction and Assessment High school students can investigate the effects of a solution of simulated acid rain (4 ml of 1 M sulfuric acid in 2 L of distilled water) on various materials that might come in contact with acidic rain, such as brick, marble, concrete, assorted plant leaves, wood, different types of soils, metals, and plastics. Students can brainstorm what materials to test and bring in their own samples. The results can lead to a discussion about the possible effects of acid rain on the natural and built environment. (Safety notes: Have students wear sanitized goggles, nitrile gloves, and aprons throughout the activity. Have eyewash and shower stations within 10 seconds access in case of a splash. Review and share safety instructions for handling sulfuric acid. Be sure students wash their hands with soap and water after completing the activity.) Students can research the efforts being made to reduce the harmful effects of acid rain. A starting place for teachers is the following Environmental Protection Agency website: www.epa.gov/acidrain/reducing. Students can create their own experiments to test the effects of acid rain on plant germination. Obtain a variety of fast-germinating seeds to sprout in various environments: pure water, normal rain (captured on a rainy day), simulated solution of acid rain (4 ml of 1 M sulfuric acid in 2 L of distilled water), and diluted 154 vinegar. (Safety notes: Have students wear sanitized goggles, nitrile gloves, and aprons throughout the activity. Have eyewash and shower stations within 10 seconds access in case of a splash. Review and share safety instructions for handling sulfuric acid. Be sure students wash their hands with soap and water after completing the activity.) Make connections to wind patterns to show how factory and coal plant emissions from one region in the United States (e.g., the Midwest) can affect the air and water in another region (e.g., New England). References American Association for the Advancement of Science (AAAS). 2009. Benchmarks for science literacy online. www.project2061.org/ publications/bsl/online. Darcin, S. 2010. Trainee science teachers’ ideas about environmental problems caused by vehicle emissions. Asia-Pacific Forum on Science Learning and Teaching 11 (2): Article 14. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London: RoutledgeFalmer. Khalid, T. 2001. Preservice teachers’ misconceptions regarding three environmental issues. Canadian Journal of Environmental Education 6 (1): 101–120. National Research Council (NRC). 2012. A framework for K–12 science education: Practices, crosscutting concepts, and core ideas. Washington, DC: National Academies Press. N a t i o n a l S c i e n c e Te a c h e r s A s s o c i a t i o n Copyright © 2016 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions. TO PURCHASE THIS BOOK, please visit www.nsta.org/store/product_detail.aspx?id=10.2505/9781938946479