1. Biogeochemical cycles
Biological, geological and chemical processes through which an element circulates throughout the environment.

2. Carbon Cycle (ST)

3. Exchanges of Carbon on Earth
Plants undergo photosynthesis, plants are start of all food chains.
6 CO2 + 6 H2O + energy  6O2 + C6H12O6 (*EST)
Animals (herbivores) eat plants or animals (carnivores) eat other animals that contain C.
Living organisms respire
6 O2 + C6H12O6  6 CO2 + 6 H2O + energy (*EST)

4. - Animal’s waste decompose and CO2 + CH4 is emitted.
- Forest fires release CO2.
- CO2 dissolves in water and reacts with calcium to become calcium carbonate. The carbonate rock comes to the surface through volcanic activity.
- Fossil fuels form from dead organisms that fall to the ocean floor and fossilize.

5. Nitrogen Cycle (ST)

6. Exchanges of Nitrogen on Earth
Nitrogen is necessary to manufacture proteins and DNA.
NITROGEN FIXATION: Bacteria in the soil or water can convert N2 into NH3
NITRIFICATION: Bacteria oxidize NH3 to form nitrites. Other bacteria convert nitrites to nitrates.

7. NITROGEN absorption: Plants absorb ammonium and nitrates from soil or water. ANIMALS MUST EAT PLANTS or EAT OTHER ANIMALS to obtain nitrogen.
DECOMPOSITION: Bacteria converts wastes into ammonium
DENITRIFICATION: Bacteria convert nitrates to N2 for the atmosphere.

8. Phosphorus Cycle (*EST)

9. Exchanges of Phosphorus on Earth*(EST)
P is a basic component of DNA; needed for shells and bones of animals.
Erosion: Phosphorus occurs in rocks in the form of phosphates; small amounts erode.
Plants absorb phosphates . Herbivores (plant eating) animals ingest the phosphates and carnivores eat herbivores.

10. Phosphates are released in feces and are released when dead plants and animals decompose.
Phosphates from rock, animals, decomposers, fertilizers, detergents make their way to the ocean. Eventually sink to the bottom and slowly form into rock to return phosphorus to its original state.