Biogeochemical cycle

For life to exist on our planet, many processes are required, most of which occur naturally. Among them is the  biogeochemical cycle . In a kind of recycling, because through us, the earth, air, animals, plants and water circulate elements that are released and stored in turn and that nourish, energize and provide minerals necessary for existence. There are several types of cycles within the ecosystem and each element that is produced has its own cycle.

What is a biogeochemical cycle?

The biogeochemical cycle is a biological, chemical and geological process in which certain elements are detached, circulated and stored within the terrestrial ecosystem , establishing a link and movement between living beings and those who do not. This cyclical system recycles mineral nutrients that organisms require for their development and life.

  • What does it consist of?
  • Characteristics of the biogeochemical cycle
  • Types of biogeochemical cycle
  • Importance
  • Examples of biogeochemical cycle

What does it consist of?

Sunlight provides us with energy, which flows into the planet and is released as heat. However, certain chemical compounds found in living organisms are recycled. For example, the body atoms of humans have spent a long time fulfilling a recycling process in the biosphere and, while they fulfill this task, along the way they are integrated into multiple living or non-living forms of the ecosystem . Different chemicals are created from organic molecules. These are stored for different periods of time in the earth’s crust and atmosphere , as well as in organisms.Geological activities such as rock deterioration, erosion and water infiltration contribute to the recycling of the elements and their contact with the receptors. All these movements and connections are called the biogeochemical cycle.

Characteristics of the biogeochemical cycle

The main characteristics of the biogeochemical cycle are:

  • They have reserves and accumulate inorganic and organic matter
  • The materials flow dynamically in the tanks.
  • With the exception of water, the elements undergo chemical modifications in their composition.
  • They are found in the three states of matter: gas, liquid and solid.
  • The time for replacement is higher in the land area than in the marine area.

Types of biogeochemical cycle

Depending on the way materials are recycled, the biogeochemical cycle can be:

  • Gaseous : The materials are dispersed between the waters and the atmosphere and then reused.
  • Sedimentary : Materials accumulate on the surface of the land or sea beds. It takes a long time for microorganisms to recycle them.
  • Mixed : It is when the two previous types are combined, that is, through sediments and gases.

Interconnected cycles

Biogeochemical cycles can be in three different ways depending on their interconnection. These are:

  • Hydrological : It occurs when the waters move and connect with the entire ecosystem and distribute heat on the earth’s surface.
  • Nutrients : It is when the compounds move on the earth’s surface, living beings and hydrosphere. Recycling is slow. Some like sulfur or phosphorus spend millions of years in sediment rocks.
  • Gaseous : The circulation is atmospheric and among living organisms. Recycling is fast. Some elements take hours like oxygen, nitrogen or carbon.


Our planet has a closure system in which it is not possible for matter to leave or enter. That is why it is vital that the substances we use are not lost and that the cycles that allow their reuse are maintained. According to the physiological requirements we selectively capture the chemical-elements. All the processes in which they flow, transform, accumulate and recycle generate life. Even when dying, molecules are released that are used after the recycling and reserve systems that occur in ecosystems and outside them. This cyclical dynamism is essential for survival.

Examples of biogeochemical cycle

Some examples of the biogeochemical cycle are:

Biogeochemical cycle of water

This refers to its transfer from one place to another , and to achieve this, it manifests itself in its three states: liquid, gaseous and solid. It is visible on our planet since it is in a liquid state in seas, rivers, oceans and other bodies of water. In solid state it is found in glaciers and mountains. In the gaseous state it is in the clouds. Its circulation is constant as it goes through various processes, thanks to the heating of the solar rays that evaporate, condense and reach the entire environment.

Cycle of nitrogen

Nitrogen is an indispensable component . Its presence in the atmosphere is numerous. It is essential for building carbohydrates, proteins, phospholipids, and nucleic acids. It intervenes in biological and abiotic processing. It reaches life cycles thanks to bacteria that embed it from the atmosphere and make it part of its macromolecules. Some species of these microscopic beings are the Rhizobium (inhabits the roots of legumes) and the Azotobacter. To return to atmospheric air when it is already in organic matter, it goes through 3 steps:

  • Ammonification : When plants and animals die they decompose and fungi and bacteria act there . In the process nitrogen is released as ammonia or ammonia.
  • Nitrification : Both ammonia and ammonium are converted into nitrites by the intervention of bacteria called nitrosantes , among them are Nitrosomonas. Later, these nitrites become nitrates, also due to bacterial causes.
  • Assimilation : Vegetables and plants absorb nitrates in their roots. Upon reaching plant cells, ammonium reappears to synthesize amino acids. This component is found in proteins that will later be ingested by animals and humans. Another step is also taken in the soil, since the decomposition of nitrates that is generated will release gaseous nitrogen that will rise to the atmosphere.

Some human activities also release nitrogen into the ecosystem, such as burning fossil fuel or using chemical fertilizers on crops.

Carbon cycle

It occurs when in the compounds that contain this mineral, transformations occur naturally. It occurs in the layers of the Earth where there are living beings: lithosphere, biosphere, hydrosphere and atmosphere. This biogeochemical cycle is slow and occurs in water, air and land. When atmospheric carbon mixes with water, carbonic acid arises, this ionizing creates bicarbonate and carbonate ions. Bicarbonate ions represent 90% of the element present in the oceans. After processes of change and sedimentation, they reach the seashells as lime, this type being the most extensive mineral deposits on the planet. To return to the air and complete the cycle, it is released after volcanic explosions, erosionfrom rocks, burning of fossil fuel , animal respiration, by methods used in agriculture and when methane is produced.

Sulfur biogeochemical cycle

It has a complex cycle . It is concentrated to a greater degree in the lithosphere . It is found in the atmosphere as hydrogen sulfide or sulfur dioxide. To get there, it does so through the disintegration of organic molecules, the eruption of volcanoes and geothermal pathways; and by human action and / or use of fossil fuel.

Biogeochemical cycle of phosphorus

It is fundamental for existence. It has the ability to enter organisms, water, and soils constantly. It accumulates mostly in rocks, so it is primarily sedimentary. The earth’s crust has its largest reservoirs. It occurs frequently in organisms as phosphate ions, in cell membranes, energy molecules, cell metabolism, and in bones. In its cycle there is no presence of gaseous components, almost the entire system is caused by rocky wear that releases it to the soil as phosphate, it goes into the water and then into the air, where it can be part of the food chain. The element is used in agricultural production to fertilize the land. Through this use (irrigation, rain) is also released into bodies of water.

Calcium cycle

It circles its cycle that goes from living beings and the ecosystem where it is found. Its recycling is continuous. It is very present in the interior of animals and humans in its form of calcium ion or being integrated into different molecules. Also in the bones. It is vital as a support, in addition to helping the movement of the muscles or in coagulation. In the environment it is like calcium bicarbonate and it regularly seeps into rivers until it migrates to oceans and seas.

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