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Anton Cwik , Ethan Sox

Anton Cwik , Ethan Sox. Per. 4. BIOGEOCHEMICAL CYCLES. ‘ Fundamentals ’ of biogeochemical cycles. All matter cycles...it is neither created nor destroyed... As the Earth is essentially a closed system with respect to matter, we can say that all matter on Earth cycles .

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Anton Cwik , Ethan Sox

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  1. Anton Cwik, Ethan Sox Per. 4


  3. ‘Fundamentals’ of biogeochemical cycles • All matter cycles...it is neither created nor destroyed... • As the Earth is essentially a closed system with respect to matter, we can say that all matter on Earth cycles . • Biogeochemical cycles: the movement (or cycling) of matter through a system

  4. by matter we mean: elements (carbon, nitrogen, oxygen) or molecules (water) so the movement of matter (for example carbon) between these parts of the system is, practically speaking, a biogeochemical cycle The Cycling Elements: macronutrients : required in relatively large amounts "big six": carbon , hydrogen , oxygen , nitrogen , phosphorous sulfur

  5. other macronutrients: potassium , calcium , iron , magnesium micronutrients : required in very small amounts, (but still necessary) boron (green plants) copper (some enzymes) molybdenum (nitrogen-fixing bacteria)





  10. 6 of the most important cycles are the water, carbon, nitrogen, sulfur, phosphorus and oxygen.

  11. 1. Which part of the atmosphere has the highest altitude?A. Troposphere B. Stratosphere C. Thermosphere D. Mesosphere2. Which part includes all three of the other parts?Lithosphere B. Ecosphere C. Hydrosphere D. Atmosphere3. Which one is not a major cycle?A. Hydrogen B. Nitrogen C. Oxygen D. Sulfur E. Water



  14. HUMAN IMPACTS TO WATER CYCLE • Water withdrawal from streams, lakes and groundwater. (salt water intrusion and groundwater depletion) • Clear vegetation from land for agriculture, mining, road and building construction. (nonpoint source runoff carrying pollutants and reduced recharge of groundwater) • Degrade water quality by adding nutrients(NO2, NO3, PO4) and destroying wetlands (natural filters). • Degrade water clarity by clearing vegetation and increasing soil erosion.

  15. Water Quality Degradation



  18. Explain

  19. Carbon in Oceans • Additional carbon is stored in the ocean. • Many animals pull carbon from water to use in shells, etc. • Animals die and carbon substances are deposited at the bottom of the ocean. • Oceans contain earth’s largest store of carbon.


  21. 1. What is no part of the water cycle?A. Precipitation B. Percolation C. Transpiration D. Surface Runoff E. Boiling2. Which is not a man made way of adding carbon to the carbon cycle?A. Airplanes B. Natural Fires C. Cars D. Burning fossil fuels3. What are the predictions for how much carbon will be added from fossil fuels?A. Low B. Medium-Low C. Medium D. High

  22. The Nitrogen Cycle

  23. Sources • Lightning • Inorganic fertilizers • Nitrogen Fixation • Animal Residues • Crop residues • Organic fertilizers

  24. Forms of Nitrogen • Urea  CO(NH2)2 • Ammonia  NH3 (gaseous) • Ammonium  NH4 • Nitrate  NO3 • Nitrite  NO2 • Atmospheric Dinitrogen N2 • Organic N

  25. Global Nitrogen Reservoirs

  26. Roles of Nitrogen • Plants and bacteria use nitrogen in the form of NH4+ or NO3- • It serves as an electron acceptor in anaerobic environment • Nitrogen is often the most limiting nutrient in soil and water.

  27. Nitrogen is a key element for • amino acids • nucleic acids (purine, pyrimidine) • cell wall components of bacteria (NAM).

  28. Nitrogen Cycles • Ammonification/mineralization • Immobilization • Nitrogen Fixation • Nitrification • Denitrification

  29. N2 N2O NH4 NO2 R-NH2 NO NO2 NO3

  30. Which of the following is not part of the Nitrogen Cycle? A) Ammonification B) Nitrification C) Denitrosation D) Nitrogen Fixation E) Denitrification In what form(s) do plants and bacteria use nitrogen? A) NH4+ B) NH3 C) NO3- D) A and C E) All of the above What is the molecular formula for ammonium? A) NH4+ B) NH3 C) NO3 D) NO2 E) none of the above

  31. Ammonification or Mineralization N2 N2O NH4 NO2 R-NH2 NO NO2 NO3

  32. Mineralization or Ammonification • Decomposers: earthworms, termites, slugs, snails, bacteria, and fungi • Uses extracellular enzymes  initiate degradation of plant polymers • Microorganisms uses: • Proteases, lysozymes, nucleases to degrade nitrogen containing molecules

  33. Plants die or bacterial cells lyse  release of organic nitrogen • Organic nitrogen is converted to inorganic nitrogen (NH3) • When pH<7.5, converted rapidly to NH4 • Example: Urea NH3 + 2 CO2

  34. Immobilization • The opposite of mineralization • Happens when nitrogen is limiting in the environment • Nitrogen limitation is governed by C/N ratio • C/N typical for soil microbial biomass is 20 • C/N < 20Mineralization • C/N > 20 Immobilization

  35. Nitrogen Fixation N2 N2O NH4 NO2 R-NH2 NO NO2 NO3

  36. Nitrogen Fixation • Energy intensive process : • N2 + 8H+ + 8e- + 16 ATP = 2NH3 + H2 + 16ADP + 16 Pi • Performed only by selected bacteria and actinomycetes • Performed in nitrogen fixing crops (ex: soybeans)

  37. Azobacter Beijerinckia Azospirillum Clostridium Cyanobacteria Require the enzyme nitrogenase Inhibited by oxygen Inhibited by ammonia (end product) Microorganisms fixing

  38. Rates of Nitrogen Fixation

  39. Immobilization is the opposite of which process in the cycle? A) Mineralization B) Nitrification C) Immobilization D) Nitrogen Fixation E) Denitrification What process takes place when nitrogen is limiting in the environment? A) Mineralization B) Nitrification C) Immobilization D) Nitrogen Fixation E) Denitrification Which has the highest rate of nitrogen fixation? A) Rhizobium-legume B) Cynaobacteria-moss C) Rhizosphere associations D) Free-living E) Azobacter

  40. Applications to wetlands • Occur in overlying waters • Aerobic soil • Anaerobic soil • Oxidized rhizosphere • Leaf or stem surfaces of plants

  41. Bacterial Fixation • Occurs mostly in salt marshes • Is absent from low pH peat of northern bogs • Cyanobacteria found in waterlogged soils

  42. Nitrification N2 N2O NH4 NO2 R-NH2 NO NO2 NO3

  43. Nitrification Two step reactions that occur together : • 1rst step catalyzed by Nitrosomonas 2 NH4+ + 3 O2 2 NO2- +2 H2O+ 4 H+ • 2nd step catalyzed by Nitrobacter • 2 NO2- + O2  2 NO3-

  44. Optimal pH is between 6.6-8.0 • If pH < 6.0  rate is slowed • If pH < 4.5  reaction is inhibited In which type of wetlands do you thing Nitrification occurs?

  45. Denitrification N2 N2O NH4 NO2 R-NH2 NO NO2 NO3

  46. Denitrification • Removes a limiting nutrient from the environment • 4NO3- + C6H12O6 2N2 + 6 H20 • Inhibited by O2 • Not inhibited by ammonia • Microbial reaction • Nitrate is the terminal electron acceptor

  47. Looking at the Nitrogen cycle through the eye of NH4

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