1. Biogeochemical Cycles

2. Hydrologic Cycle
Another name for the water cycle!

3. Oxygen Cycle
Plants take in carbon dioxide and release oxygen during photosynthesis.
Humans and other organisms take in oxygen and release carbon dioxide during respiration.

4. Carbon Cycle
Carbon is found in the atmosphere in solid, liquid, and gas forms
CO2 gas
Fossil fuels
Rocks and organic matter
Plants take CO2 out of the atmosphere
Respiration, burning fossil fuels, factory and auto emissions releases it
Areas called carbon sinks (such as cellulose in wood in forests) store carbon

5. Nitrogen Cycle Nitrogen gas makes up 78% of the atmosphere
Most organisms can only use it in the form of ions such as ammonium (NH4+) or nitrate (NO3-)
Bacteria can convert nitrogen into NH4 by a process called nitrogen fixation
Nitrogen flows through the food chain
Nitrogen gas is eventually released back into the atmosphere by denitrifying bacteria

7. Phosphorus Cycle
Phosphate is released by weathering rocks and taken up by producers
Phosphate moves up the food chain and when organisms die, it is released back to the soil or water.