1. Biogeochemical Cycles
Biogeochemical cycles facilitate the transfer of matter from one form to another and from one location to another on planet earth.
Additionally, biogeochemical cycles are sometimes called nutrient cycles
they involve the transfer of compounds that provide nutritional support to living organisms.

2. Pathways
Biosphere is the region occupied by living organisms such as plants and animals
Lithosphere is the region occupied by soil, land and the earth crust)
Atmosphere refers to air and space
Hydrosphere (areas covered by water such as rivers, lakes and oceans)

3. Oxygen Cycle Almost all living things need oxygen.
They use this oxygen during the process of creating energy for their cells.

5. Oxygen Cycle: Pathway

6. Reservoirs
The place where an element is held or stored for a long period of time

7. Reservoirs for Oxygen
The largest reservoir of oxygen is the atmosphere
This is due to photosynthesis
Other reservoirs include the ocean and lithosphere (soil, litter)

8. Chemical Reactions
Photosynthesis:
Cellular Respiration:

9. Human Interventions