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Investigation of Acid Deposition Trends in the United States. April 16, 2013. Instructions .
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Investigation of Acid Deposition Trends in the United States April 16, 2013
Instructions This investigation will require you to analyze a series of graphs, maps, and charts which together provide a picture of the how the effects of acid deposition vary both temporally (with time) and spatially (with location) in the United States. Acid deposition refers to air pollutants which upon reacting with water vapor in the troposphere form acid particles (dry deposition) or droplets (wet deposition) which fall to the Earth. These are commonly and collectively called acid rain. Review the graphs, maps, and charts in this presentation. After each there are a series of questions. Answer these questions and then submit your answers on a separate sheet of paper. Click to the next slide to begin.
Figure 1: Questions • Explain how a pollutant might be transferred from an urban area (factory) to a rural area (forest)? Even if there were not humans on Earth to alter the atmosphere, rainfall would be acidic because atmospheric carbon dioxide and water combine to form carbonic acid, which has a pH of about 5.6 on the pH scale. Rainwater with a pH less than 5 is considered acid rain. However, the pH of rainwater varies from place to place and also over time during a rain event. 2. Considering this information, do you think that the pH of rainwater tends to increase (become more basic) or decrease (become more acidic) over the course of a storm event?
Figure 2: pH of Convective Storm of 3 August 1972 near St. Louis, MO The variation of pH (closed circles) with time during the convective storm of 3 August 1972. The rainfall rate (open circles) in millimeters per hours (mm hr-1) is shown. From Richard G. Semonin, Temporal and Spatial Variability of Rainfall pH)
Figure 2: Questions 3. How did the pH values compare as the 3 August 1972 storm progressed? Why? 4. Is there a relationship between rainfall amount and rainfall pH during this storm? 5. Normally, the pH of rainwater increases over the course of a storm. Why might this be the case? Propose a mechanism to explain the observations from Figure 2.
Figure 3: Questions 6. What is the primary source of sulfur dioxide emissions? 7. Describe three ways these emissions can be lowered.
Figure 3: Atmospheric Sulfate Concentrations in the U.S. for the Year 2000 (in mg/L)
Figure 3: Questions continued… 8. Study Figure 3: Why are the highest values in the Midwest in southeastern Ohio? 9. Why are the values so low west of the Rock y Mountains?
Figure 4: Atmospheric Nitrate Concentrations for the Year 2000 (mg/L)
Figure 4: Questions 10. What is the primary source of NOx emissions? 11. Where are the highest concentrations on this map, and why? 12. Why are the values so low in rural central and northern California but higher east of the urban San Francisco Bay area.
Figure 5: Questions 13. How do the maps in Figures 4 and 5, point out the differences in the sources of sulfates and nitrates. 14. Explain how weather patterns and geology help distribute these substances.
Figure 6 and 7 : Questions 15. Compare Figures 6 and 7. What difference(s) do you notice? 16. What might be some reasons for the differences in sulfate ion concentration over the decade shown (2001 to 2011)?
Figure 8 and 9 : Questions 17. Using Figures 8 and 9, why are the lowest pH (most acid) values generally in the Northeast? 18. Describe four ways that acid rain hurts the economy of the United States.
Conclusion Question One market-based incentive for reducing pollution is called Tradable Emissions Limitations of emissions trading for short. The approach used by the EPA is called Allowance Trading, or cap-and-trade. Research current approaches to reducing industrial pollution and answer the following: 19. How does the EPA’s allowance trading work for sulfur dioxide trading? 20. Where has this approach been tried, and why was that area selected? 21. How effective is the program?
