1. BIOGEOCHEMICAL CYCLES

2. ‘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

3. 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

4. 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)

5. 6 of the most important cycles are the water, carbon, nitrogen, sulfur, phosphorus and oxygen.

6. WATER HYDROLOGIC CYCLE

7. CONNECTS ALL OF THE CYCLES AND SPHERES TOGETHER
HYDROLOGIC CYCLE
CONNECTS ALL OF THE CYCLES AND SPHERES TOGETHER

8. 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.

9. Water Quality Degradation

10. MARINE CARBON CYCLE

11. TERRESTRIAL CARBON CYCLE

12. Sources of Carbon from Human Activity
Explain
Natural Sources of
Carbon
Sources of Carbon from Human Activity
Death of plants and animals
Animal waste
Atmospheric CO2
Weathering
Methane gas from cows (and other ruminants)
Aerobic respiration from terrestrial and aquatic life
Burning wood or forests
Cars, trucks, planes
Burning fossil fuels such as coal, oil and natural gas to produce heat and energy.

13. 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.

15. IMPORTANCE OF CARBON CYCLE
CARBON IS THE BACKBONE OF LIFE!

16. The Nitrogen Cycle

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

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

20. Global Nitrogen Reservoirs
Metric tons nitrogen
Actively cycled
Atmosphere
3.9*1015 No
Ocean  soluble salts
Biomass
6.9*1011
5.2*108
Yes
Land  organic matter
 Biota
1.1*1011
2.5*1010
Slow

21. 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.

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

23. Nitrogen Cycles Ammonification/mineralization Immobilization
Nitrogen Fixation
Nitrification
Denitrification

24. Ammonification or Mineralization
NH4
NO2
R-NH2 NO
NO2
NO3

25. 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

26. 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

27. 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

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

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

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

31. Rates of Nitrogen Fixation
N2 fixing system
Nitrogen Fixation (kg N/hect/year)
Rhizobium-legume
Cyanobacteria- moss
30-40
Rhizosphere associations
2-25
Free- living
1-2
Rhizobium-legume
Cynaobacteria-moss
Rhizosphere associations
Free-living

33. 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
Mineralization
Immobilization
Rhizobium-legume

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

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

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

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

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

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

40. 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

41. PHOSPHOROUS CYCLE

42. HUMAN IMPACTS TO PHOSPHOROUS CYCLE
Humans mine LARGE quantities of phosphate rock to use in commercial fertilizers and detergents. Phosphorous is NOT found as a gas, only as a solid in the earth’s crust. It takes millions to hundreds of millions of years to replenish.
Phosphorous is held in the tissue of the trees and vegetation, not in the soil and as we deforest the land, we remove the ability for phosphorous to replenish globally in ecosystems.
Cultural eutrophication – ad excess phosphate to aquatic ecosystems in runoff of animal wastes from livestock feedlots, runoff of commercial phosphate fertilizers fro cropland, and discharge of municipal sewage.

43. IMPORTANCE OF PHOSPHOROUS CYCLE
1.Phosphorous is an essential nutrient of both plants and animals.
2. It is part of DNA molecules which carry genetic information.
3. It is part of ATP and ADP) that store chemical energy for use by organisms in cellular respiration.
4. Forms phospholipids in cell membranes of plants and animal cells.
5. Forms bones, teeth, and shells of animals as calcium phosphate compounds.

44. SULFUR CYCLE

45. HUMAN IMPACTS TO SULFUR CYCLE
Approximately 1/3 of all sulfur emitted into atmosphere comes from human activities.
1. Burning sulfur containing coal and oil to produce electric power (SOx = acid deposition).
2. Refining petroleum – (SOx emissions)
3. Smelting to convert sulfur compounds of metallic minerals into free metals (Cu, Pb, Zn)
4. Industrial processing.

46. IMPORTANCE OF SULFUR CYCLE
Sulfur is a component of most proteins and some vitamins.
Sulfate ions (SO4 2- ) dissolved in water are common in plant tissue. They are part of sulfur-containing amino acids that are the building blocks for proteins.
Sulfur bonds give the three dimensional structure of amino acids.
Many animals, including humans, depend on plants for sulfur-containing amino acids.

47. The Oxygen cycle

49. “GOOD OZONE UP HIGH”

50. PHOTOCHEMICAL SMOG “BAD OZONE DOWN LOW”

51. OZONE DEPLETION