Biogeochemical Cycle

A biogeochemical cycle is the process through which a chemical substance cycles between Earth’s biotic and abiotic compartments. The biosphere is a biotic compartment, whereas the atmosphere, hydrosphere, and lithosphere are abiotic compartments. Chemical elements including calcium, carbon, hydrogen, mercury, nitrogen, oxygen, phosphorus, selenium, iron, and Sulphur have biogeochemical cycles, as do molecular elements like water and silica. Macroscopic cycles, such as the rock cycle, and human-induced cycles for synthetic substances like polychlorinated biphenyls are also present (PCBs). There are reservoirs in some cycles where a material can stay or be sequestered for a long time. 

What is a Biogeochemical Cycle? 

“Biogeochemical cycles relate to the movement of nutrients and other elements between biotic and abiotic factors in an ecosystem. 

The phrase “biogeochemical” is formed from the words “biosphere,” “geo,” and “chemical,” which refer to the elements that flow through a cycle. 

Atoms are the most fundamental unit of matter, which is how it is maintained and organised here on Earth. Due to the fact that matter cannot be created or destroyed, it is recycled in a variety of different ways throughout the earth’s system. 

In a closed system, all of the other elements are present, and the earth draws energy from the sun, which is then converted into heat and radiated back into space. The following constitutes the essential elements: 

• Carbon 
• Hydrogen 
• Nitrogen 
• Oxygen 
• Phosphorus 
• Sulphur 

These elements are recycled by the ecosystem’s biotic and abiotic components. The ecosystem’s abiotic components include the atmosphere, hydrosphere, and lithosphere. 

Types of Biogeochemical Cycles 

There are two primary types of biogeochemical cycles: 

 1.Carbon, Oxygen, Nitrogen, and the Water Cycle are all examples of gaseous cycles. 

 2.Sulphur, Phosphorus, Rock Cycle, and Other Sedimentary Cycles. 

Take a quick look at each of these biogeochemical cycles: 

Water Cycle 

The water from the many bodies of water evaporates, cools, condenses, and falls as rain. 

This biogeochemical cycle is in charge of keeping meteorological conditions stable. Water interacts with its environment in numerous forms, changing the temperature and pressure of the atmosphere. 

This process is aided by another mechanism known as evapotranspiration (i.e., vapour generated by leaves). Water evaporates from leaves, soil, and water bodies into the sky, where it condenses and falls as rain. 

Water Cycle

Water changes state from one phase to another throughout this process, although the overall number of water particles stays constant. In other words, even if 100 gms of water could be collected and boiled, it would still maintain a mass of 100 gms as steam. 

Stages of Water Cycle 

1. Evaporation

When water molecules on the surface of water bodies become stimulated and rise into the air, evaporation occurs. Water vapor clouds form when the molecules with the highest kinetic energy collect. Evaporation occurs when water is below its boiling point. Evaporation via the leaves of plants is another process known as evapotranspiration. This mechanism is responsible for a significant amount of water in the atmosphere. 

2. Sublimation

On mountain tops, when the air pressure is very low, sublimation can be seen. Because less energy is used in the process of sublimating the snow into water vapor, the low air pressure aids the process. The phase where fog bellows from dry ice is another example of sublimation. The ice sheets that cover the earth’s poles are the principal source of sublimation on the planet. 

3. Condensation

Due to the low temperatures seen at high altitudes, the water vapour that has collected in the atmosphere ultimately cools down. These vapours condense into small droplets of water and ice, which eventually condense into clouds. 

4. Precipitation

The vapours condense into water droplets as the temperature rises above 0 degrees Celsius. It cannot, however, condense without the presence of dust or other contaminants. As a result, water vapours adhere to the particle’s surface. It falls off of the sky and onto the land below when enough drops combine. Precipitation is the name for this procedure (or rainfall). Water droplets freeze and fall as snow or hail in exceptionally cold conditions or when air pressure is extremely low. 

5. Runoff

If rainfall does not create aquifers, it falls victim to gravity and flows down the slopes of mountains and hills, eventually producing rivers. Runoff is the term for this procedure. When the volume of snowfall exceeds the rate of evaporation or sublimation, in colder places, icecaps develop. The poles are home to the world’s largest ice caps. 

All of the preceding processes proceed in a cyclical manner, with no definite beginning or conclusion. 

Carbon Cycle 

Carbon is transferred among the biosphere, geosphere, hydrosphere, atmosphere, and pedosphere in one of the biogeochemical cycles. 

Photosynthesis is carried out by all green plants using carbon dioxide and sunshine. As a result, the plant stores carbon. When green plants die, they are buried in the soil, where they are transformed into carbon-based fossil fuels. When fossil fuels are burned, carbon dioxide is released into the atmosphere. 

Animals that eat plants also get the carbon that is stored in the plants. When these creatures disintegrate after death, the carbon is released back into the atmosphere. Carbon is also returned to the environment via animals’ cellular respiration. 

Huge amounts of carbon dioxide are created, which are stored as fossil fuels (coal and oil) and may be harvested for a variety of commercial and non-commercial applications. When these fuels are used in factories, the carbon is discharged back into the atmosphere. 

Nitrogen Cycle 

It is the biogeochemical cycle in which nitrogen is transformed into various forms and circulates through the atmosphere as well as numerous ecosystems, including terrestrial and marine ecosystems. 

Nitrogen is a necessary component of life. The nitrogen-fixing bacteria found in the root nodules of leguminous plants fix nitrogen in the atmosphere and make it accessible to the soil and plants. 

This nitrogen gas is converted into an useful molecule called ammonia by bacteria found in the roots of plants. Plants are also given ammonia in the form of fertilisers. Nitrites and nitrates are formed from ammonia. Denitrifying bacteria convert nitrates to nitrogen, which is then released into the atmosphere. 

Oxygen Cycle 

The atmosphere, lithosphere, and biosphere all participate in this biogeochemical cycle. Oxygen is a plentiful element on our planet. It is present in the atmosphere in the elemental form to the level of 21%. 

Photosynthesis causes plants to release oxygen. Humans and other creatures consume oxygen and exhale carbon dioxide, which is absorbed by plants again. They use this carbon dioxide to make oxygen through photosynthesis, and the cycle repeats. 

Phosphorus Cycle 

Phosphorus flows through the hydrosphere, lithosphere, and biosphere in this biogeochemical cycle. The weathering of rocks extracts phosphorus. Phosphorus is carried away in the soil and water bodies as a result of rain and erosion. Plants and animals get phosphorus from the soil and water and use it to thrive. Phosphorus is also required for the development of microorganisms. When plants and animals die, their stored phosphorus is released into the soil and water bodies, where it is eaten by plants and animals again, and the cycle repeats. 

Sulphur Cycle 

This biogeochemical cycle passes through rocks, bodies of water, and living organisms. Weathering of rocks releases Sulphur into the atmosphere, which is then transformed into sulphates. Microorganisms and plants absorb these sulphates and convert them to organic molecules. Animals receive organic Sulphur through their diet. Sulphur is returned to the soil when animals die and disintegrate, where it is acquired again by plants and bacteria, and the cycle repeats. 

Importance of Biogeochemical Cycles 

These cycles explain how the energy is utilised. These cycles transport the needed ingredients for life to survive across the biosphere. They are essential because they recycle and store materials, as well as control key elements through physical features. These cycles reflect the interactions between living and nonliving organisms in ecosystems and allow ecosystems to continue to exist. 

Conclusion  

To summarise, none of these distinct biogeochemical cycles occur in isolation. The passage of water through the water cycle is the most significant connecting connection. The release of phosphate and nitrogen into diverse water bodies, including the seas, is dependent on the velocity of water.