1. The Cycling of Materials

2. Why Learn About This?
Most minerals essential for life cycle between living things and the atmosphere or the ground
Atmosphere—gases surrounding Earth
Biosphere—living ‘layer’ of Earth
Lithosphere—soil/rock layer of Earth
Earth is a “closed” ecosystem
The only thing in is sun (energy), the only thing out is some heat(energy)

3. Cycles in the Biosphere
The law of conservation of mass states that matter is not created or destroyed.
Therefore , natural processes cycle matter through the biosphere.
Involves both matter in living organisms and physical processes in the environment. (e.g. weathering)

4. The Carbon Cycle
All living things are composed primarily of carbon (organic) compounds
Carbohydrates
Proteins
Lipids
Nucleic acids

5. The Carbon Cycle - Processes
Photosynthesis: Plants take in CO2 from the atmosphere and convert it into sugars, which are then used by other organisms (heterotrophs)
Respiration: Organisms respire and release CO2 back into the atmosphere
Combustion: CO2 is also produced by burning fossil fuels
CO2 traps heat in the atmosphere, so the more CO2 in the atmosphere, the hotter the atmosphere, but we’ll talk more about this later…..

6. The Carbon Cycle - Processes
Death and Decay: Decomposers release CO2 into the atmosphere when they break down organic compounds. Fossils fuels were produced by the decay of ancient organisms.

7. Carbon “Sinks” Storage
Organisms – complex organic compounds
Atmosphere – CO2, CO, CH4
Litter and Waste – complex organic compounds
Fossil fuels - hydrocarbons
Industry and vehicles – hydrocarbons and other organic compounds
Oceans – shells CaCO3
Lithosphere – limestone CaCO3

8. Carbon Cycle Short Term
Green plants and algae convert CO2 in the atmosphere along with water into carbohydrates.
These carbohydrates are used as a source of energy for all other organisms
CO2 is recycled when autotrophs and heterotrophs release it back into air during celllular respiration.

9. They are opposite

10. Carbon Cycle Long Term
Carbon enters a long-term cycle when organic material is buried underground and converted to peat, oil, coal or gas.
This can take millions of years
Carbon is released when fossil fuels are burned
Carbon can also enter in a long term cycle in the form of calcium carbonate (found in shells of marine animals) when they fall to the ocean floor and create vast deposits of limestone rock. Carbon is released due to weathering and erosion

11. Carbon Cycle

13. The Nitrogen Cycle Nitrogen is an important element for organisms!
Nitrogen is found in all proteins, and all nucleic acids in all organisms!
We all need nitrogen!

14. The largest concentration (pool) of nitrogen N2 is found in the atmosphere (78% of the gases in the atmosphere; 98% of the total nitrogen on Earth)
Plants and animals cannot use nitrogen directly from the atmosphere!

15. Nitrogen Fixation: Taking Nitrogen from the Atmosphere
Atmospheric nitrogen must be captured by nitrogen-fixing bacteria that live in the soil and plant roots and converted to ammonia. This process is called biological nitrogen fixation.
Nitrogen can also be fixed into a useable form by lightning or the activities of factories in industry (manufacturing fertilizers)

16. Ammonification
Nitrogen is returned to soil by urination and dead organisms. Decomposers break down the nitrogen from these to ammonia through ammonification.
This is all well and good, but ammonia is toxic to most living cells…

17. Nitrification: Making Nitrogen Useable to Organisms
Soil bacteria (nitrifying bacteria) convert ammonia into nitrites (NO2-) and nitrates (NO3-) through nitrification

18. Assimilation: Getting the Nitrogen into Organisms
Beans, peas, clover and alfalfa use the nitrogen directly from the bacteria in their roots to make amino acids and nucleic acids.
Other plants absorb nitrates from soil and convert into amino acids.
Consumers get nitrogen when they eat plants or animals that contain it.

19. Denitrification: Returning Nitrogen to the Atmosphere
Anaerobic denitrifying bacteria in the soil convert nitrates back into nitrogen N2 through denitrification which returns to atmosphere.

21. Nitrogen Cycle

22. The Phosphorus Cycle
Phosphorus is essential for the growth and development of organisms.
There is a short term and long term cycle.
Short term is cycled from soil to producers to consumers. Waste and decomposition return it to soil to be used again.
Long term is from sedimentation to form rocks and is released due to weathering and erosion
Phosphorus may be present in only small amounts and can limit the growth of producers

23. Review of Basic Concepts in Nutrient Cycling

24. So, in conclusion….
Nutrients (chemicals) we (and other living things) need for life functions, often come from the ground or the air
As we carry out life functions, these chemicals are returned to the air or the ground, and the cycles start over again
Similar to chemicals, energy also moves through ecosystems, but we’ll talk about that later…
…and that’s all for today, folks!!!