1. Human Impact on the Biosphere Ecosystems as affected by Human activity

2. Human Impacts  Humans are using energy and altering the environment at astonishing rates  We are altering natural processes before we even understand them

3. Pollutants  Substances with which an ecosystem has had no prior evolutionary experience  No adaptive mechanisms are in place to deal with them

4. Air Pollutants  Carbon oxides  Sulfur oxides  Nitrogen oxides  Volatile organic compounds  Photochemical oxidants  Suspended particles

5. Industrial Smog  Gray-air smog  Forms over cities that burn large amounts of coal and heavy fuel oils; mainly in developing countries  Main components are sulfur oxides and suspended particles

6. Photochemical smog  Brown-air smog  Forms when sunlight interacts with components from automobile exhaust  Nitrogen oxides are the main culprits  Hot days contribute to formation

7. Thermal Inversion  Weather pattern in which a layer of cool, dense air is trapped beneath a layer of warm air cool air warm inversion air cool air

8. Acid Deposition  Caused by the release of sulfur and nitrogen oxides  Coal-burning power plants and motor vehicles are major sources

9. Ozone Thinning  In early spring and summer ozone layer over Antarctica thins  Seasonal loss of ozone is at highest level ever recorded South America Antarctica

10. Effect of Ozone Thinning  Increased amount of UV radiation reaches Earth’s surface  UV damages DNA and negatively affects human health  UV also affects plants, lowers primary productivity

11. Protecting the Ozone Layer  CFC production has been halted in developed countries, will be phased out in developing countries  Even with bans it will take more than 50 years for ozone levels to recover

12. Generating Garbage  Developed countries generate huge amounts of waste  Paper products account for half the total volume  Recycling can reduce pollutants, save energy, ease pressure on landfills

13. Deforestation  Removal of all trees from large tracts of land  38 million acres logged each year  Wood is used for fuel, lumber  Land is cleared for grazing or crops

14. Effects of Deforestation  Increased leaching and soil erosion  Increased flooding and sedimentation of downstream rivers  Regional precipitation declines  Possible amplification of the greenhouse effect

15. Regions of Deforestation  Rates of forest loss are greatest in Brazil, Indonesia, Mexico, and Columbia  Highly mechanized logging is proceeding in temperate forests of the United States and Canada

16. Destroying Biodiversity  Tropical rainforests have the greatest variety of insects, most bird species  Some tropical forest species may prove valuable to humans  Our primate ancestors evolved in forests like the ones we are destroying

17. Desertification  Conversion of large tracts of grassland to desertlike conditions  Conversions of cropland that result in more than 10 percent decline in productivity

18. Ongoing Desertification  Sahel region of Africa is undergoing rapid desertification  Causes are overgrazing, overfarming, and prolonged drought  One solution may be to substitute native herbivores for imported cattle

19. Water Use and Scarcity  Most of Earth’s water is too salty for human consumption  Desalinization is expensive and requires large energy inputs  Irrigation of crops is the main use of freshwater

20. Negative Effects of Irrigation  Salinization, mineral buildup in soil  Elevation of the water table and waterlogging  Depletion of aquifers

21. Aquifer Problems

22. Water Pollutants  Sewage  Animal wastes  Fertilizers  Pesticides  Industrial chemicals  Radioactive material  Excess heat (thermal pollution)

23. Wastewater Treatment  Primary treatment Use of screens and settling tanks Use of screens and settling tanks Addition of chlorine to kill pathogens Addition of chlorine to kill pathogens  Secondary treatment Microbes break down organic matter Microbes break down organic matter  Tertiary treatment removes additional toxic substances; rarely used

24. Energy Use  Only 10 percent of energy used in developed countries is from renewable sources  Less developed countries rely more heavily on renewable sources (primary biomass)

25. Fossil Fuels  Coal, oil, natural gas  Main energy source of developed countries  Burning of fossil fuels contributes to global warming

26. Oil  Reserves are declining  Many reserves are in ecologically fragile wilderness areas  Environmental costs of extracting and transporting reserves from such areas are high

27. Coal  Extensive reserves exist  Mining is very destructive  Burning coal releases sulfur dioxides that cause acid deposition

28. Nuclear Energy  Used extensively in some energy- poor developed countries…clean production of energy.  Controversial in the United States  Emits very few air pollutants but creates radioactive waste (must be securely stored)  Potential for meltdown ??

29. Chernobyl Accident - 1986  Core meltdown at a nuclear power plant in the Ukraine  31 immediate deaths, radiation sickness and death for others  Cloud of radiation spread by winds across Europe  Long-term health impacts downwind

30. Solar-Hydrogen Energy  Photovoltaic cells use sunlight energy to split water  Hydrogen gas produced in this way can be used as fuel or to generate electricity  Clean, renewable technology

31. Wind Energy  An indirect use of solar energy  Wind farms are arrays of turbines  Can supplement needs of some regions but is not dependable enough on it own

32. Fusion  Energy is released when atomic nuclei fuse  This process produces solar energy  Attempts to mimic this process on Earth require use of lasers, magnetic fields  Not yet a commercially viable energy source