Biology Topics related to disease and health provide critical insights into human physiology and medicine.
What is Carbon Cycle – An Overview
Carbon is an important constituent of organic compounds found in all living beings in the form of carbohydrates, fats, proteins, and nucleic acids. Like the water cycle, the carbon cycle is linked to energy flow because producers – including photosynthetic plants of the forests and oceans and chemosynthetic bacteria of deep-sea vents – require environmental energy (either sunlight or inorganic hydrogen compounds) to trap carbon into sugars (proteins and fats). The trapped carbon comes from carbon dioxide in the surrounding air or water.
As the cycle proceeds, consumers devour the organic carbon compounds that producers manufacture. Then, via respiration, both consumers and producers return carbon to the nonliving environment in the form of carbon dioxide. Some carbon accumulates for many years in wood and is eventually returned to the atmosphere by fires or through consumption and respiration by fungi, bacteria, and other detritivores. The volcanic eruption also releases carbon dioxide into the atmosphere. Thus, there is complete cycling of carbon in the environment by various living and non-living beings.
The Carbon Sinks
Some of the cycling materials in the physical environment may pass into a reservoir or sink, and become unavailable to organisms for eons. For example, there are at least three reservoirs for the carbon:
- Some carbon passes from organisms into deposits of peat, coal, and oil. There it waits, perhaps millions of years before combustion, either natural or human-induced, releases it back into the atmosphere.
- Some carbon gets incorporated into carbonate rocks, where it is unavailable to organisms for millions of years until erosion releases it.
- The oceans also act as carbon sinks. Carbon present in ocean water sinks and stays deep in the ocean until chance currents bring it back near the surface where it can reenter the carbon cycle.
In addition to CO2, two other forms of carbon are present in the atmosphere in small amounts: carbon monoxide (CO) and methane (CH4). Both arise from the incomplete or anaerobic decomposition of organic matter; are oxidized to CO2 in the industry.
The carbon cycle. Carbon tends to cycle from the atmosphere to Plants, Animals, Detritivores, Decomposers, Human activities (cars, chimneys of factories, etc.), and Back. Carbon cycles from atmospheric carbon dioxide to biological molecules to organic molecules in the soil to geologic deposits of fossil fuels and back to carbon dioxide. Disruption of this cycle can lead to increased atmospheric carbon dioxide and global warming.
An amount of carbon monoxide (CO) equal to that formed by natural decomposition is injected into the air by the incomplete burning of fossil fuels, especially in automobile exhaust. Carbon monoxide is a deadly poison to humans. It does not pose a global threat but has become a worrisome pollutant in urban areas.
Methane (CH4) is a colourless, flammable gas that is produced naturally by the decomposition of organic matter by anaerobic bacteria, especially in freshwater wetlands, rice paddies, and digestive tracts of ruminants (such as cattle) and termites. It is also a major component of natural gas, so the geochemical disturbances associated with mining and drilling for fossil fuels result in the release of methane. Methane has the potential of increasing its contribution to global warming.