1. The Cycling of Matter
Energy flows in one direction starting as solar radiation and finally leaving as heat
Nutrients Cycle!
Absorbed by organisms from the soil and atmosphere
Circulate through
trophic levels
Released back to
the ecosystem

2. Biogeochemical Cycles
Around 40 elements cycle through ecosystems
All have organic and inorganic phases
Major Cycles: water, carbon, nitrogen, sulphur, and phosphorus
Shared Characteristics:
Very different than energy
Energy is eventually lost
Matter is finite and recycled
Death-Decompose-
nutirents released- taken up
by plants again. (biogeochemical)

3. The Carbon Cycle Where is carbon stored? (sinks) Organic Inorganic
Organisms (biomass)
Fossilized Life (fossil fuels)
Inorganic
Sedimentary Rock (locked up for millions of years)
Oceans (dissolved or locked up as carbonates)
Soil
Small amount in the atmosphere (live measurement)

4. Carbon Flows Cycles between living and non living
Fixed by photosynthesis and returned to the atmosphere by respiration
Also released when dead organisms decompose
Also released through the burning of fossils fuels
Photosynthesis = Carbon Fixation

5. Humans and the Carbon Cycle
Additions
Global emissions from fossil fuel burning is about 5.5 GtC (10^9 tonnes)
20%Natural gas; 40% Coal, 40% Oil
Another 1.6 GtC are added through deforestation
That is 7.1 GtC/year
Uptake
New forest growth takes up
~0.5GtC
Oceans/phytoplankton take up
~ 2.4 GtC
There is about GtC we
aren’t sure about
Since the pre-industrial period we
have added 200GtC to the atmosphere

6. The Nitrogen Cycle
Nitrogen is essential for proteins and DNA so who needs it?
Nitrogen Fixation: When atmospheric N2 is made available to plants. Goes from gaseous N to ammonia. (5 options)
1. Free living nitrogen fixing bacteria in soil (Azotobacter)
2. Symbiotic bacteria in root nodules of legumes (Rhizobium)
3. cyanobacteria (important to rice production)
4. Lightning oxidizes nitrogen gas to nitrate
5. Haber Process: Nitrogen and Hydrogen combined under pressure with iron catalyst (fertilizer production)

7. The Nitrogen Cycle Nitrification Denitrification Decomposition
Some bacteria convert ammonia to nitrite
Others convent nitrite to nitrate
Plant roots readily absorb nitrates
Denitrification
Other bacteria often associated with water logged or low oxygen soil reverse the process and Nitrogen gas is returned to the atmosphere.
Decomposition
Also provides nitrogen for uptake by plants
Way more than nitrogen fixation
Assimilation
After uptake
Nitrogen is used in
Building complex
molecules

8. Humans and the Nitrogen Cycle
Removal of animals and plants for food removes nitrogen from the system
The Nitrogen is lost because it ends up in the human sewage system instead of the ecosystem
Fertilizer
Haber process makes more nitrogen
Planting legumes can increase nitrogen
Cultural Eutrophication

9. Phosphorus cycle Very slow Limited amount found in the soil
(On Human time scale it flows in one direction from the land to the oceans)
Limited amount found in the soil
Limiting factor for plant growth
Excess causes prolific plant growth
algal blooms in water (Eutrophication)
We mine the phosphate out of rock and add it to fertilizers and detergents

10. Do we have phosphates in our bodies?

11. The Phosphorous Cycle
Is Phosphorous ever a gas in the air?

12. Sulfur cycle Natural sources of Sulfur (enter atm)
Hydrogen sulfide (swamps/volcanoes)
Sulfur dioxide SO2 (volcanoes)
Marine Algae produce DMS (dimethyl sulfide)
Comes out of decaying material
Reacts in atmosphere to create hydrogen sulfate (H2SO4) sulfuric acid (acid rain)

13. The Sulfur Cycle

14. Effects of Human Activities on the Sulfur Cycle
We add sulfur dioxide to the atmosphere in 3 ways:
We burn coal and oil to produce electricity.
Refine petroleum to make gasoline
Convert sulfur containing mineral ore into free-metals
ex: Pyrite is Iron Sulfide, to get Iron sulfur is released