Biogeochemical Cycles

Biogeochemical Cycles

1. The Carbon Cycle

   • 1: Carbon enters the atmosphere as carbon dioxide from respiration and combustion
     • 2: Carbon dioxide is absorbed by producers (like plants) to make carbohydrates in photosynthesis .These producers then put off oxygen.
       • 3: Animals feed on the plants. Most of the carbon these animals consume however is exhaled as carbon dioxide. This is through the process of respiration. The animals and plants then eventually die
         • 4: The dead organisms are eaten by decomposers in the ground. The carbon that was in their bodies is then returned to the atmosphere as carbon dioxide. The decomposed plants and animals may then be available as fossil fuel in the future for combustion.

2. The Nitrogen Cycle

   • 1: A special type of bacteria called nitrogen fixing bacteria take in atmospheric nitrogen and produce ammonia
     • 2: Other bacteria use this ammonia to produce nitrates and nitrites, which are nitrogen and oxygen containing compounds
       • 3: The nitrates and nitrites are used by plants to make amino acids which are then used to make plant proteins.
         • 4: Plants are consumed by other organisms which use the plant amino acids to make their own.
           • 5: Decomposers convert the nitrogen found in other organisms into ammonia and return it to the soil. A few of these type of bacteria return nitrogen to the atmosphere

3. The Phosphorous Cycle

   • 1: Rain and weathering cause rocks to release phosphate ions and other minerals. This inorganic phosphate is then distributed in soils and water.
     • 2: Plants take up inorganic phosphate from the soil. The plants may then be consumed by animals. Once in the plant or animal, the phosphate is incorporated into organic molecules such as DNA. When the plant or animal dies, it decays, and the organic phosphate is returned to the soil.
       • 3: Within the soil, organic forms of phosphate can be made available to plants by bacteria that break down organic matter to inorganic forms of phosphorus.
         • 4: Phosphorus in soil can end up in waterways and eventually oceans. Once there, it can be incorporated into sediments over time.

4. The ways in which an element, or compoun moves between its various living and nonliving forms and locations in the biosphere is called a biogeochemical cycle

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