1. Cycles of Matter

2. Biogeochemical Cycles
Biogeochemical cycles: The circulation of substances through living organisms from or to the environment.
A pathway forms when a substance enters living organisms such as trees from the atmosphere, water, or soil; stays for a time in the living organism; then returns to the nonliving environment.

3. Water Cycle Non-living portion: Living portion:
Water vapor in the atmosphere condenses and falls to the Earth’s surface as rain or snow.
Some of the water seeps into the soil and becomes ground water.
Most of the remaining water is heated by the sun and reenters the atmosphere by evaporation.
Living portion:
Much of the water is taken up by the roots of plants.
After passing through the plant, the water moves back into the atmosphere by transpiration.

4. Carbon Cycle Four main processes move carbon through its cycle:
Biological processes such as photosynthesis, respiration, and decomposition take up and release carbon and oxygen.
Geochemical processes such as erosion and volcanic activity release carbon dioxide into the atmosphere and oceans.
Processes such as the burial and decomposition of dead organisms and their conversion under pressure to fossil fuels store carbon underground.
Human activities such as mining, cutting and burning forests, and burning fossil fuels release carbon dioxide into the atmosphere.

5. Nitrogen Cycle
All organisms require nitrogen to make amino acids (which build proteins).
To use the nitrogen gas in the air, nitrogen fixation must occur. This is a process where certain bacteria turn the nitrogen into a usable form (nitrates and nitrites).
Producers use these nitrates and nitrites to make proteins.
Consumers then eat the producers and reuse the nitrogen to make their own proteins.
When organisms die, nitrogen is returned to the ground.

6. Phosphorous Cycle
Phosphorous is necessary to life because it forms part of DNA and RNA.
Phosphorous is not very common in the biosphere.
Though it cycles through the earth and organisms, phosphorous never enters the atmosphere.