1. Biogeochemical Cycles

2. Something to think about…
A handful of elements combine to form the building blocks of all known organisms.
Organisms cannot manufacture these elements and do not “use them up,” so where do essential elements come from?

3. Objectives: Identify the elements of Life
Identify and describe the flow of elements (“nutrients”) in each biogeochemical cycle.
Explain the impact that humans have on the biogeochemical cycles.

4. Two Secrets of Survival: Energy Flow and Matter Recycling
An ecosystem survives through a combination of energy flow and matter recycling.

6. Unlike the one-way flow of energy, matter is recycled within and between ecosystems.
As matter moves through these cycles, it is never created or destroyed — just changed.

7. Why is it important that matter is recycled?
They are required to build and maintain an organism

8. Elements of Life

9. Essential Elements 24 elements are required for life
Macronutrients are required in LARGE quantities
carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.
Micronutrients are required in small/medium quantities, or not at all in some organisms
Copper, sodium, iodine

10. How does matter move through the biosphere?
A biogeochemical cycle is the complete path a chemical takes through the Earth’s four major reservoirs:
atmosphere
hydrosphere (oceans, rivers, lakes, groundwaters, and glaciers)
lithosphere (rocks and soils)
biosphere (plants and animals)

11. Chemicals enter storage compartments - sinks

12. Biogeochemical Cycles in Ecosystems
Biological Processes
any and all activities performed by living organisms; includes eating, breathing, “burning” food, and eliminating waste
Geological Processes
include volcanic eruptions, the formation & breakdown of rock, and major movements of matter within and below the surface of the earth
Chemical / Physical Processes
include the formation of clouds and precipitation, flow of running water, and the action of lightning

13. Hydrologic (Water) Cycle

14. Carbon Cycle Carbon is vital for life but is not abundant
Enters biological cycles through photosynthesis to produce organic forms of carbon

15. Carbon Cycle in a Pond

16. Fossil Fuels
Lack of oxygen or low temperatures may prevent decomposition of dead organisms
Burial in sediments over thousands or millions of years transforms the stored organic carbon into coal, oil or natural gas

17. Global Carbon Cycle

18. Nitrogen Cycle

19. Nitrogen Cycle Essential for manufacturing proteins and DNA
Although 80% of atmosphere is molecular nitrogen, it is unreactive and cannot be used directly
Nitrogen fixation converts nitrogen to ammonia or nitrate

20. Nitrogen Fixation
Some organisms have a symbiotic relationship with nitrogen fixing bacteria
Found in root nodules in some plants, or in the stomach of some herbivores
Nitrogen fixation also occurs through lightning and industrial processes

21. Denitrification
When organisms die, denitrifying bacteria convert organic nitrogen to ammonia, nitrate, or molecular nitrogen .

22. Nitrogen Cycle

23. Global Phosphorus Cycle

24. Phosphorus Cycle No gaseous phase Slow rate of transfer
Released by erosion of exposed rock
Absorbed by plants, algae, and some bacteria
Exported from terrestrial ecosystems by runoff to oceans
May be returned through seabird guano

25. Phosphate Mining
Impact on landscape by open-pit mining

26. Sulfur Cycle In a Forest Ecosystem
Includes gaseous forms (sulfur dioxide and hydrogen sulfide);cycles much faster than calcium

27. Calcium Cycle in a Forest Ecosystem
Soluble in water and easily lost through runoff

28. Remember…
Biogeochemical cycles of matter pass the same atoms and molecules around again and again.
If you interrupt the cycling, how does this affect the ecosystem?

29. Case of the missing carbon!
Analysis shows contribution of 8 .5 bill. tons into the atmosphere but less than ½ stays there…where does it go?
7 billion from fossil fuels and 1.5 billion from deforestation

30. Case of the missing carbon!
Appears oceans are acting as carbon sinks as are forests and grasslands.
But which area is more critical, and which one dominates.
Will these blessings last?
If they stop functioning we could face drastic changes even before 2050.

31. Case of the missing carbon!
Global tests of CO2 show less in the north than the south despite larger northern outputs
Why is this the case?
If land plants are doing the work then there should be a corresponding oxygen increase.
If it is dissolving in the oceans then there should be no added oxygen.

32. Case of the missing carbon!
Results (best guess):
Ocean is soaking up 2.4 billion tons globally
Land plants do the most work in the northern hemisphere
Forests literally breath in the carbon but appetite changes dramatically due to season, amount of sunlight, rainfall, and age of forests
Marine organisms undergo photosynthesis as well
So that leaves about 2.9 units unaccounted for between these groups.

33. Case of the missing carbon!
Biggest threats:
Decline in forest growth
Killing of ocean phytoplankton due to rising sea temperatures
Death of forests due to spread of disease and insects
Melting permafrost layer
Land clearing for development and agriculture
Ofcourse continued output of carbon from fossil fuel burning