1. Biogeochemical Cycles

2. 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

3. Reservoir
chemicals for long periods of time in one place and are generally abiotic
Example: coal deposits

4. Exchange Pools
chemicals are held for only short periods of time and are generally biotic
Example: plants and animals (which temporarily use carbon in their systems and then release back into the air)

6. Biogeochemical Cycle
circuit or pathway by which a chemical element or molecule moves through both biotic ("bio-") and abiotic ("geo-") compartments of an ecosystem.
In effect, the element is recycled

7. BIO
Biology. Life. Living things. These cycles all play a role in the lives of living things. The cycles might limit the organisms of Earth or they might happen along side, changing the environment

8. GEO
Earth. Rocks. Land. This refers to the non-living processes at work. Oxygen cycles through many systems. It's in you and plants for the 'bio' part of the cycle. Oxygen might also wind up in rocks. The 'geo' part of its cycle.

9. Chemical
Molecules. Reactions. Atoms. All cycles include these small pathways. Complete molecules are not always passed from one point to the next. Sometimes chemical reactions take place that changes the molecules and locations of the atoms. Think about oxidation as an example of the
'chemical' part of these pathways.

10. What are the main cycles?
In a gas cycle elements move through the atmosphere. Main reservoirs are the atmosphere and the ocean.
In a sedimentary cycle elements move from land to water to sediment. Main reservoirs are the soil and sedimentary rocks.

11. What are the Biogeochemical Cycles of interest to Ecology?
Carbon Cycle (gas)
Nitrogen Cycle (gas)
Oxygen Cycle (gas)
Phosphorous Cycle (sedimentary)
Sulfur Cycle (sedimentary)
Hydrogen Cycle (gas)
Water Cycle
Mercury Cycle (new one)
human caused cycle of atrazine (new one)

12. What does it need? It always involves equilibrium states:
a balance in the cycling of the element between compartments.
However, overall balance may involve compartments distributed on a global scale.

13. What sustains life on Earth?

14. Secrets to Survival
An ecosystem survives by a combination of energy flow and matter recycling

15. Matter cycling in ecosystems
Nutrient Cycles: Global Recycling
Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms.
Nutrients are the elements and compounds that organisms need to live, grow, and reproduce.
Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.

17. Oxygen Cycle

18. THE CARBON CYCLE

19. What Is Carbon? An element The basis of life of earth
Found in rocks, oceans, atmosphere

20. Carbon Cycle
The same carbon atoms are used repeatedly on earth. They cycle between the earth and the atmosphere.

21. Plants Use Carbon Dioxide
Plants pull carbon dioxide from the atmosphere and use it to make food –— photosynthesis.
The carbon becomes part of the plant (stored food).

22. Animals Eat Plants
When organisms eat plants, they take in the carbon and some of it becomes part of their own bodies.

23. Plants and Animal Die
When plants and animals die, most of their bodies are decomposed and carbon atoms are returned to the atmosphere.
Some are not decomposed fully and end up in deposits underground (oil, coal, etc.).

24. Carbon Slowly Returns to Atmosphere
Carbon in rocks and underground deposits is released very slowly into the atmosphere.
This process takes many years.

25. Cycle – Repeats Over and Over and Over and Over …
42% CO2 returned by plants, 46% by decomposers, animals by12%

26. Carbon Cycle Diagram Carbon in Atmosphere
Plants use carbon to make food
Animals eat plants and take in carbon
Plants and animals die
Decomposers break down dead things, releasing carbon to atmosphere and
soil
Bodies not decomposed — after many years, become part of oil or coal deposits
Fossil fuels are burned; carbon is returned to atmosphere
Carbon slowly released from these substances returns to atmosphere

27. 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.

29. The Carbon Cycle

30. Human Impact Fossil fuels release carbon stores very slowly
Burning anything releases more carbon into atmosphere — especially fossil fuels
Increased carbon dioxide in atmosphere increases global warming
Fewer plants mean less CO2 removed from atmosphere

31. What We Need to Do Burn less, especially fossil fuels
Promote plant life, especially trees

32. Nitrogen Cycle

34. Nitrogen Cycle

35. Effects of Increased Nitrogen
1. Loss of soil nutrients (calcium, potassium)
Acidification of rivers and lakes (fertilizers and combustion of coal).
Increases nitrogen oxides in the atmosphere
(greenhouse gas—global warming).
(reduce ozone—increasing UV penetration).

36. Effects of Increased Nitrogen
4. Aids in spreading weeds into nitrogen poor areas (+Eutrophication of lakes, ponds, streams).
5. Increasing nitrogen increases carbon fixation (linked to carbon cycle).
6. Increasing acidification increases weathering (increases rate of phosphorous cycle).

38. Phosphorus Cycle

39. Phosphorus Cycle

40. Diagram of Phosphorus Cycle

41. Sulphur Cycle

42. Sulphur Cycle

43. Sulphur Cycle

45. Biogeochemical Cycle = Recycling
All the chemicals, nutrients, or elements — such as carbon, nitrogen, oxygen, phosphorus — used in ecosystems by living organisms operate on a closed system

46. Gaia Hypothosis
Some have proposed that the earth’s various forms of life control or at least influence its chemical cycles and other earth-sustaining processes.
The strong Gaia hypothesis: life controls the earth’s life-sustaining processes.
The weak Gaia hypothesis: life influences the earth’s life-sustaining processes.

47. Conclusions
In contrast to energy, which moves in one direction through the ecosystem, materials are continually recycled from the abiotic environment to organisms, and back to the abiotic environment.
Changes in one of the biogeochemical cycles usually influences the other biogeochemical cycles.