Exercises

10.1. (a) What are the main causes of imbalance in the carbon cycle?

(b) How many tons of methane from natural gas would have to be burned to increase the carbon dioxide content of the atmosphere by 10% assuming that no competing removal processes occurred at the same time?

(c) Discuss the possible means of sequestering carbon dioxide so that it does not enter the atmosphere.

10.2. Make a list of the atmospheric contaminants released by combustion of coal.

10.3. A particular 4000-MW power station burns 10 million tonnes of 3% sulfur coal a year. How many tonnes of limestone would be used up in scrubbing the SO2 from the stack gases? If the final product is oxidized to gypsum, how many tonnes of gypsum would be produced? If this were disposed of as a solid in a landfill, what volume would it occupy? Is this a realistic estimate of the actual disposal volume?

10.4. Why is nitrogen gas inert?

10.5. What is meant by the terms nitrification and denitrification? Write some reactions that take place in these processes.

10.6. How are ammonia and nitric acid produced commercially? List the environmental problems associated with these processes.

10.7. What are the main sources of nitrogen oxides in the atmosphere?

10.8. What are the main sources of sulfur oxides in the atmosphere?

10.9. Describe the reactions that atmospheric nitrogen and sulfur oxides undergo that lead to their removal from the atmosphere.

10.10. How does fertilizer use contribute to atmospheric problems?

10.11. List the elements that are known to be essential for human health. List those believed to be essential whose role have not yet been definitely established.

10.12. Write the chemical reactions that are involved in the conversion of NO* to HNO3 in the environment.

10.13. A particular flow of water from a mine has a flow of 200 liters/min of water at pH 2. How many grams of sulfuric acid per day does this represent?

10.14. Compare the environmental chemistry of iron and manganese.

10.15. Discuss the pros and cons of using copper sulfate as an algicide in a small lake used for fishing and swimming.

10.16. Cr(VI) (as chromate) is a strong oxidizing agent that can oxidize most organic materials; nevertheless it can exist for considerable periods of time in biological systems. Discuss why this can be so.

10.17. Why is Cr(VI) as the chromate ion more readily transported into cells than Cr(III)?

10.18. Outline the reactions through which metallic mercury is converted into methylmercury in a body of water.

10.19. Mercury is found in fluorescent lights. What is its purpose?

10.20. Summarize the structures, uses, and hazards of organotin compounds.

10.21. What are the most common sources of ingested lead?

10.22. Explain how the amount of lead used over time can be inferred from analysis of Greenland ice. How does lead in the rest of the world get transported to Greenland?

10.23. Explain the relationship between arsenic poisoning and wallpaper.

10.24. Calculate the pE conditions under which selenite would become the stable form at pH 7. What pE would be required for Se(0) to be the stable form?

10.25. How many grams (ounces) of swordfish containing 1 ppm Hg would a person weighing 50 kg have to consume to reach the recommended daily maximum intake of 0.1 ^g per kilogram of body weight?

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