2. The Biogeochemical Cycles

3. © 2003 John Wiley and Sons Publishers Fig 4.5 Periodic table of the elements.

4. D. T. Krohne, General Ecology

5. © 2003 John Wiley and Sons Publishers Fig 4.6 Idealized diagram of the geologic cycle, which includes the tectonic, hydrologic, rock and biogeochemical cycles.

6. Modified from D. T. Krohne, General Ecology 15%/year CO 2 & CH 4

8. The Carbon Cycle

9. © 2003 John Wiley and Sons Publishers Fig 4.14 The Carbon Cycle.

10. © 2003 John Wiley and Sons Publishers Fig 4.15 Idealized diagram illustrating photosynthesis for a green plant (tree) and generalized reaction.

12. © 2003 John Wiley and Sons Publishers Fig 4.17 Global flux of carbon, 1850-1990.

13. Modified from D. T. Krohne, General Ecology 50% fertilizer (Bacteria)

14. Microbial mediated processes in the nitrogen cycle

15. Nitrogen fixation Cyanobacteria live everywhere in the aquatic environment Nitrogen fixing bacteria in plant root nodules Microbes fix nitrogen gas into ammonia that is incorporated into plant tissue

16. Ammonification (Mineralization) Refers to the breakdown of organic matter in order to release the organically bound nitrogen as inorganic (mineral) nitrogen in the form of ammonia Decomposition is the biological process that allows for the process

17. Nitrifying bacteria (Nitrosomonas and Nitrobacter)

18. Occurs in oxygen poor or anaerobic environments usually deep in the soil or in muddy sediments

19. NO 3 - NO 3 - → NO 2 - → NO → N 2 O → N 2 gasNO 2 -NON 2 ON 2 The complete denitrification process can be expressed as a redox reaction 2NO 3 - + 10e - + 12H + → N 2 + 6H 2 O

20. Mangrove swamps are areas where denitrification happens

21. From http://www.epa.gov/maia/html/nitrogen.htmlhttp://www.epa.gov/maia/html/nitrogen.html

22. © 2003 John Wiley and Sons Publishers Fig 4.19 The global nitrogen cycle.

23. © 2003 John Wiley and Sons Publishers Critical Thinking Issue – How are Human Activities Affecting the Nitrogen Cycle? Increased nitric acid in soil: Leaching of magnesium and potassium Increased aluminum levels Plant root damage Changes in microbe communities Fish kills Eutrophication of water bodies Nitrates in drinking water Global effects on plant based CO 2 uptake Effects of increased use of nitrogen fertilizer:

24. D. T. Krohne, General Ecology Modified from D. T. Krohne, General Ecology Gaseous phase

25. Phosphorous cycle in water

26. © 2003 John Wiley and Sons Publishers Fig 4.20 The global phosphorus cycle.

27. Ecosystems and the Gaia Hypothesis

28. Ecosystem defined: a community of organisms and it’s corresponding abiotic environment through which matter cycles and energy flows Wide variation in ecosystems Boarders can be well defined or vague Can be natural or artificial, managed or wild Wide range in scale Common to all ecosystems: energy flow and cycling of matter

30. Gaia Hypothesis(es) Life has greatly affected the planetary environment This alteration has allowed life to persist The Earth is a “super-organism” - Life controls the environment in a fashion that is equivalent to the way an organism controls its various systems Evolution?

32. Prepare for a quiz on the topic