Home >> Science & Nature >> Nature

Description of a Biogeochemical Cycle

As you go about your day, there are natural cycles occurring all around you. These cycles are called biogeochemical cycles and they are vitally important to all life on Earth. When you are soaked by a sudden rainstorm, you are experiencing a biogeochemical cycle and when you exhale, you are contributing to another biogeochemical cycle. These cycles, as massive and crucial to life as they are, are actually simple to understand.

Definition
- A biogeochemical cycle is an ecological construct that describe how a particular chemical moves from living beings to nonliving objects on the Earth (such as land), then into the atmosphere and back to the living beings. All of the chemicals and elements that are a part of any living creature are a part of some type of biogeochemical cycle. The term "biosphere" represents all living things on the Earth. Chemicals move from the biosphere to the lithosphere (land masses) to the atmosphere (air) and back to the biosphere. Water, carbon, nitrogen and oxygen are the most important chemicals involved in biogeochemical cycles.
Biosphere and Systems
- Animals contribute chemicals to biogeochemical cycles through a variety of means. When animals exhale, they contribute carbon to the carbon cycle. When animals excrete liquid waste, they contribute to the water cycle. Lastly, when animals die, they decompose and contribute to the nitrogen cycle. Biogeochemical cycles can be either closed or open systems. In a closed system, which includes all cycles except the energy cycle, no new chemicals are created; they are only recycled. The energy cycle, in which the sun's rays give energy to the Earth, is an open system; new energy is constantly being sent to the Earth.
Lithosphere
- Chemicals pass from animals to the land, though they can also go directly to the Earth's water (hydrosphere) or directly to the atmosphere. Some chemicals, such as water, pass from animals to land, then to water and the atmosphere relatively quickly. In these cases, the chemicals are held in exchange pools. When the chemicals remain stored away in the land for a long time (millions of years), they are held in reservoirs. For example, coal locked away in the Earth is held in coal reservoirs.
Atmosphere
- The chemicals in most biogeochemical cycles eventually make their way into the atmosphere. They arrive in the atmosphere mostly in gaseous form and remain in the atmosphere for a very short time. They also usually return to the earth in gaseous form, except for water which returns to the Earth as a liquid.

Nature