Importance of Biochemistry

Biogeochemical cycles definition biology?

What are the main characteristics of biogeochemical cycles?

What are Biogeochemical Cycles and why are they important?

Biogeochemical cycles:

Biogeochemical cycles are defined as the  processes that occur in nature to ensure the recycling of chemical elements in the environment.

It is these cycles that allow the elements to interact with the environment and with living beings, that is, ensure that the element flows through the atmosphere, the hydrosphere, the lithosphere and the biosphere.

The main biogeochemical cycles found in nature are the water, carbon, oxygen and nitrogen cycles.

Content Index

  • 1 Types of biogeochemical cycles and characteristics
    • 1.1 Biogeochemical water cycle
    • 1.2 Biogeochemical nitrogen cycle
    • 1.3 Biogeochemical oxygen cycle
    • 1.4 Biogeochemical phosphorus cycle
    • 1.5 Sulfur biogeochemical cycle
  • 2 Importance

Types of biogeochemical cycles and characteristics

Biogeochemical water cycle

Water is an element that moves and transforms all the time. Therefore, we can find it in nature in all three states: solid, liquid and gas.

The biogeochemical cycle of water is characterized exactly by its change in physical state . Let’s see how it happens, in stages:

  • In the first stage, the evaporation of water from rivers, lakes and oceans goes hand in hand with the perspiration of water, present in plants.
  • After evaporation and perspiration, the water (in a gaseous state) passes to the clouds, where condensation occurs, that is, the transformation to the liquid state.
  • With the accumulation of water droplets that formed in the condensation, the precipitation of the water occurs and, consequently, the rain returns it to the rivers, lakes, oceans and soils.

characteristics of the biogeochemical cycles

Biogeochemical nitrogen cycle

The biogeochemical cycle of nitrogen begins with nitrogen in its gaseous form (N2) present in the environment . At this point, it is important that nitrogen is fixed in the soil, that is, that the soil absorbs it.

This process is called fixation and occurs thanks to the help of bacteria and cyanobacteria that are present in the soil.

With the nitrogen already fixed in the soil, the next step is to transform it into ammonia, a process called ammonification.

The ammonia produced will be absorbed by bacteria that generate nitrites, and this step is called nitrification.

Nitrites will produce nitrates, which will be used in the assimilation process so that plants can synthesize proteins, and will also be used in denitrification, which is nothing more than the return of nitrogen to the environment.

The sequences of this cycle are:

  • Fixation
  • Ammonification
  • Nitrification
  • Denitrification

Observation: assimilation to plants is an event that occurs as a result of the cycle, that is, it is not carried out within the cycle.

Biogeochemical oxygen cycle

First, it is important to remember that oxygen is part of the organic and inorganic molecules.

The biogeochemical cycle of oxygen begins in photosynthesis , when the plant absorbs CO2, producing the oxygen that will be released into the atmosphere.

This oxygen that is present in the atmosphere is absorbed by animals and humans.

In addition, it can also participate in the decomposition process and in the burning of fossil fuels.

These two processes will generate and release to the atmosphere the CO2 that will be used in photosynthesis, resuming the cycle.

Biogeochemical phosphorus cycle

Phosphorus is an element that is present in the genetic material and in the molecule that provides us with energy: adenosine triphosphate, or simply ATP.

The biogeochemical cycle of phosphorus occurs in soils, plants and animals. For starters, plants absorb it from soil and water.

Animals and humans, on the other hand, get phosphorus through food.

When living things die and decompose, the phosphorus is returned to the soil and water, thus renewing the cycle.

Biogeochemical Sulfur Cycle

Sulfur is an essential element in the life of living beings, because it participates in the composition of our amino acids for the production of proteins in our body.

This element is found in rock sediments and in the soil , where it is absorbed by plants with the help of bacteria and then dissolved in water.

This water evaporates, becoming acid rain and returning the sulfur to the soil, giving sequence to the biogeochemical cycle of sulfur.


Biogeochemical cycles  are very important for living beings because they exchange these elements between the environment and living things,  helping to maintain life .

They also prevent these elements from ending in the nature of the Earth.

The biogeochemical cycles  promote the cycle of the elements,  ensure their use  and, subsequently, their  availability .

This is a factor of great importance, because some elements are essential for living beings, and their constant use, without replacement, could cause the extinction of species.

In addition, decomposing agents have the important role of restarting cycles, returning elements to the ecosystem and maintaining continuous flow.

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