Ch 5 ppt

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Ch 5 ppt

  1. 1. Chapter 4 Biogeochemical Cycles Lake Washington Case Study
  2. 3. What is a biogeochemical cycle? <ul><li>Path a chem takes through air, water, soil, orgs. and back to air or soil </li></ul><ul><li>Time taken to cycle varies. </li></ul><ul><li>Gaseous elements faster </li></ul><ul><li>Non-gaseous slower </li></ul>
  3. 4. Geologic Cycles <ul><li>Tectonic Cycle </li></ul>
  4. 6. <ul><li>Top layer ( lithosphere ) is constantly created and destroyed. Large segments (tectonic plates) move past one another. </li></ul><ul><li>Transform fault = </li></ul><ul><li>Convergent = </li></ul><ul><li>Divergent = </li></ul>
  5. 7. <ul><li>Transform fault = sliding </li></ul>
  6. 8. <ul><li>Convergent = colliding </li></ul>
  7. 9. <ul><li>Divergent = spreading </li></ul>
  8. 11. Hydrologic Cycle: Ch 19 in detail
  9. 12. Major Global Cycles <ul><li>Carbon </li></ul><ul><li>Nitrogen </li></ul><ul><li>Phosphorus </li></ul>
  10. 13. <ul><li>Where do we find C? </li></ul><ul><li>Does it have an atm stage? </li></ul><ul><li>How might carbon cycle be thrown out of balance? </li></ul><ul><li>What happens if out of balance? </li></ul>
  11. 14. The Carbon Cycle <ul><li>Gaseous (CO 2 , CH 4 ). Most important organic compound. </li></ul>
  12. 15. Nitrogen Cycle <ul><li>Where do we find N? </li></ul><ul><li>Does it have an atm stage? </li></ul><ul><li>How might the nitrogen cycle be thrown out of balance? </li></ul><ul><li>What happens if out of balance? </li></ul>
  13. 16. <ul><li>Nitrogen Cycle </li></ul><ul><li>N 2 = most of the atm (about 80%) </li></ul>110 m. tons annually 10 m. tons annually
  14. 17. <ul><li>Nitrogen cycle key steps!!: </li></ul><ul><li>First in atmosphere as N 2 </li></ul><ul><li>Then in the soil: </li></ul><ul><ul><ul><li>1. Nitrogen fixation: fixes N 2 to a form plants can use </li></ul></ul></ul><ul><ul><ul><li>2. Other bacteria convert ammonia into nitrates ( NO 3 ) </li></ul></ul></ul>
  15. 18. <ul><li>Into living things: </li></ul><ul><ul><ul><li>3. Plants absorb nitrates and ammonia by assimilation </li></ul></ul></ul>
  16. 19. <ul><li>Back into soil again: </li></ul><ul><li>Back into the atm again </li></ul>
  17. 20. 80% N 2 in atm Ammonification Nitrification step1 Nitrification step2 Assimilation Nitrogen fixation Denitrification
  18. 21. Symbiosis - Crop Rotation
  19. 22. Phosphorus <ul><li>Phosphorus has no atm stage. </li></ul><ul><li>How does this affect its’ use by l.t.s? </li></ul>
  20. 23. Phosphorus Cycle <ul><li>No gaseous phase </li></ul><ul><li>Stored in rocks and organic material in soil </li></ul><ul><li>Thanks to microbial action, changed to phosphates (PO 4 3- or HPO 4 2- )which plants can access. (slowly) </li></ul>

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