1. Biogeochemical Cycles

2. Biogeochemical Cycles
describe the flow of elements from the environment through living things and back to the environment.

3. Biogeochemical Cycles
Reservoirs
places (called reservoirs) where the elements are accumulated or held
Assimilation
Transfer of elements from the abiotic into the biotic
Release
Transfer of elements from the biotic back into the abiotic

4. Hydrological Cycle (water cycle)
Reservoirs
Open water - oceans, lakes, rivers……
Water vapor -clouds, fog
Groundwater
Glaciers, snow and ice

5. Hydrological Cycle (water cycle)
Assimilation
plants
absorb water from the ground
animals
drink water
eat other organisms which are composed mostly of water

6. Hydrological Cycle (water cycle)
Release
plants
Transpiration from leaves of plants
animals
Breathing releases water vapor
Expel liquid wastes
Evaporation off the surface of the body

7. Hydrological Cycle

8. Carbon Cycle (carbon is required for building organic compounds)
Reservoir
The atmosphere (as CO2)
Fossil fuels (oil, coal,…)
Organic materials (tissues of plants and animals).

9. Carbon Cycle (carbon is required for building organic compounds)
Assimilation
plants
use CO2 in photosynthesis
animals
consume plants or other animals made up
of carbon compounds

10. Carbon Cycle (carbon is required for building organic compounds)
Release
plants release CO2 during breathing and decomposition
animals release CO2 during breathing and decomposition
CO2 is released during combustion of fossil fuels and other materials

11. Carbon Cycle

12. Nitrogen Cycle (Nitrogen is required for the manufacture of amino acids and nucleic acids)
Reservoirs
In the atmosphere (as N2)
In the soil as
NH4+ or ammonium
NH3 or ammonia
N02- or nitrite
N03- or nitrate

13. Nitrogen Cycle (Nitrogen is required for the manufacture of amino acids and nucleic acids)
Assimilation
plants can absorb either NH4+ or N03-
animals obtain nitrogen by eating plants and other animals

14. Nitrogen Cycle (Nitrogen is required for the manufacture of amino acids and nucleic acids)
The stages in the assimilation of nitrogen:
Nitrogen Fixation:
Some bacteria turn N2 to NH4+
Lightning and radiation turn N2 to N03-
Nitrification:
Some bacteria turn NH4+ to N02- then to N03-

15. Nitrogen Cycle (Nitrogen is required for the manufacture of amino acids and nucleic acids)
Release
Denitrifying bacteria change N03- back to N2
Animals excrete NH4+ or NH3 in their urine

16. Nitrogen Cycle

17. Phosphorus Cycle (Phosphorus is required for the manufacture of ATP and all nucleic acids)
Reservoir
sediment and rocks contain phosphorus. When they erode, they transfer phosphorus into the water and soil

18. Phosphorus Cycle (Phosphorus is required for the manufacture of ATP and all nucleic acids)
Assimilation
plants absorb inorganic phosphate from the soil
animals obtain organic phosphorus when they eat plants or other animals

19. Phosphorus Cycle (Phosphorus is required for the manufacture of ATP and all nucleic acids)
Release
plants release phosphorus when they decompose
animals release phosphorus when they decompose
animals excrete phosphorus in their waste products

20. Phosphorus Cycle