Chemistry in the Environment: Atmosphere

1. Chemistry in the Environment: Atmosphere

2. Earth’s atmosphere as seen from space Photo: NASA

3. What are the natural components of our atmosphere?

4. Composition of the Atmosphere • 78 % Nitrogen • 21 % Oxygen • 1 % Argon and other trace gases

5. Layers of the Atmosphere • Troposphere • Most of our weather occurs in this layer closest to the Earth’s surface • Stratosphere • Where ozone (O3) absorbs harmful UV radiation from the Sun and prevents it from reaching Earth’s surface

6. Why do we need an atmosphere? • Atmosphere contains the air we breathe • Protects us from the Sun’s radiation • Keeps Earth balanced  traps and releases heat • Atmospheres of other planets are different • Mars very thin atmosphere made of mostly CO2 • Venus denser and hotter than Earth’s atmosphere • Jupiter large, turbulent atmosphere made of H and He

7. What are ways that human activity has negatively affected the atmosphere?

8. Fossil Fuels • Fossil fuels are fuels formed by natural resources such as anaerobic decomposition of buried dead organisms. • Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made.

9. Why do we burn fossil fuels? • We burn fossil fuels to produce useful energy • This fuel provides gas for our cars, electricity for our homes, and runs factories and powerplants

10. Burning of Fossil Fuels • The burning of fossil fuels produces around 21.3 billion tons (21.3 gigatons) of carbon dioxide (CO2) per year

11. What are ways that human activity has contributed to the pollution that causes smog and acid rain?

12. What is smog? • A type of air pollution that comes from internal combustion engines and industrial fumes that react with sunlight to form photochemical smog • The word ‘smog’ comes from a combination of smoke and fog • Mixture of air pollutants, including gases and particles that are too small to see • Smog is also caused by large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide

13. What types of air pollution cause smog? • Type:Particulate Matter - or PM. This is the name given to microscopic particles that pollute the air. They vary in size and chemical make-up.
Sources: Industrial and vehicle emissions, road dust, agriculture, construction and wood burning. • Type: Ground-level Ozone. This gas is the result of a chemical reaction when certain pollutants are combined in the presence of sunlight. Ground-level ozone shouldn't be confused with the ozone layer in the sky, which protects us from ultraviolet radiation.
Sources: Ground-level ozone comes mostly from burning fossil fuels for transportation and industry. Ozone levels peak between noon and 6 p.m. during the summer months.

14. Air Pollution Continued… • Type: Sulfur dioxideSources:Coal-fired power plants and non-iron ore smelters • Type: Carbon monoxideSources:Mostly from burning carbon fuels (e.g. motor vehicle exhaust)

15. Smog in Major US Cities

16. Smog in Major International Cities

17. Acid Rain • Acid rain is a rain or any other form of precipitation that is unusually acidic (has a low pH) • Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides which react with the water molecules in the atmosphere to produce acids

18. What are some effects of smog and acid rain on the environment?

19. Side Effects of Exposure to Smog • Asthma • Lung Cancer • Can cause coughing, chest pains, throat irritation • Colds and pneumonia

20. Adverse Effects of Acid Rain • Can damage buildings and historic monuments, especially those made of rocks such as limestone and marble containing large amounts of calcium carbonate • Soil biology and chemistry can be damaged because microbes cannot tolerate changes in pH • As lakes and river become more acidic, biodiversity is reduced • Because of low pH, fish eggs may not hatch and some adult fish are killed • Eliminates insect life and some fish species (brook trout)

21. Effect of acid rain on a forest in Jizera Mountains, Czech Republic

22. What has been done or is being done to reduce the pollution that causes smog and acid rain?

23. Acid Rain Program • Founded in 1990 by US Environmental Protection Agency (EPA) • Goal is to reduce overall atmospheric levels of sulfur dioxide and nitrogen oxides, which cause acid rain. • The program is an implementation of emissions trading that targets coal-burning plants, allowing them to buy and sell emission permits.

24. Clean up smoke stacks and exhaust pipes • There are several options for reducing SO2 emissions, including using coal containing less sulfur, washing the coal, and using devices called “scrubbers” to chemically remove the SO2 from the gases leaving the smokestack • Powerplants can use different fuels  burn natural gas instead of coal

25. Use alternate energy sources • Nuclear power • Hydropower • Wind energy • Geothermal energy • Solar energy

26. Restore a damaged environment • Takes many years for ecosystems to recover from acid rain even after emissions are reduced and rain pH is back to normal • “Liming” = a process in which limestone or lime is added to acidic lakes to cancel out the acidity • Disadvantage: expensive and short-term solution

27. Look to the future • Reducing and controlling the emissions from powerplants and cars • Implement cost-effective mechanisms to reduce emissions

28. Take action as individuals • Turn off lights, computers, and other appliances when you're not using them. • Use energy-efficient appliances: lighting, air conditioners, heaters, refrigerators, washing machines, etc. For more information, see EPA’s ENERGY STAR Program. • Only use electric appliances when you need them. • Keep your thermostat at 68°F in the winter and 72°F in the summer. You can turn it even lower in the winter and higher in the summer when you are away from home. • Insulate your home as best you can. • Carpool, use public transportation, or better yet, walk or bicycle whenever possible • Buy vehicles with low NOx emissions, and properly maintain your vehicle. • Be well informed.

29. What are ways that human activity has affected the balance of greenhouse gases in the atmosphere?

30. Greenhouse Gases • Gases which absorb and emit radiation • Greenhouse Gases (GHG): • Water Vapor • Carbon Dioxide • Methane • Nitrous Oxide • Ozone • Chlorofluorocarbons (CFCs)

31. Greenhouse Effect • The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions • The greenhouse effect keeps our planet warm • If we had no atmosphere, our Earth would be 32°C colder than it is today

32. Greenhouse Effect

33. Global anthropogenic greenhouse gas emissions for the year 2000

34. Household activities which produce Greenhouse Gases

35. What are some effects of increased greenhouse gas concentrations on the environment?

36. Increasing CO2 Concentrations

37. What does increased CO2 concentrations mean for the Earth? • Plants need CO2 to survive, and plants exposed to more CO2 could grow up to 50% faster than normal • Increased global temperature due to greenhouse effect

38. Average Global Temperatures

39. What has been done or is being done to reduce the concentration of greenhouse gases in the atmosphere?

40. What’s wrong with this picture?

41. What are ways that human activity has contributed to the reduction of the ozone layer?

42. What are some effects of the reduced ozone layer on the environment?

43. What has been done or is being done to repair the ozone layer?

44. Montreal Protocol • Treaty signed in which banned the use of CFCs and HFCs