Carbon dioxide (CO2) fixation is a vital process in photosynthesis, another vital process for all living things and the ecosystem. CO2 fixation helps to save the environment from the impact of greenhouse gas emissions.
Rather than having a pollutant in the atmosphere, living organisms convert the inorganic carbon into organic compounds that help to run life processes. This carbon is responsible for the synthesis of glucose and other important biomolecules.
Carbon dioxide fixation also helps to reduce the negative effect of climate change. It is indeed a discourse worth looking into. This article discusses the process, significance, and drawbacks.
What is carbon dioxide fixation?
Carbon dioxide fixation, carbon assimilation, or carbon capture are terms that describe the conversion of atmospheric carbon dioxide (inorganic carbon) to organic compounds.
This process is vital to the photosynthetic process in plants and algae. These living organisms take CO2 from the atmosphere and convert it into biomolecules such as carbohydrates and lipids. This is more profitable for the sustainability of the environment.
Naturally, the Earth has trace amounts of CO2 but processes such as burning fossil fuels and wood, decomposition, cellular respiration, and volcanic eruption increase the CO2 content in the atmosphere.
High amounts of this gas can cause pollution and this is not the worst that can happen due to raised CO2 concentration. Increased CO2 can be bad for human health. CO2 fixation ensures that this does not happen yet it successfully retains CO2 in the atmosphere.
Types of carbon dioxide fixation
Natural CO2 fixation
Natural CO2 fixation occurs without man’s influence. These events are invisible to the human eye but they happen. There are three methods of natural CO2 fixation:
Photosynthesis
This is the well-known and mostly discussed natural process of CO2 fixation. Photosynthesis is carried out in green plants and algae. These organisms use their chlorophyll to draw energy from the sun. This energy is in turn used to reduce CO2 to glucose and oxygen.
Glucose is a source of energy for living things and a precursor for the synthesis of glycoproteins, glycolipids, and glycosaminoglycan.
Ocean carbon pump
A lot of carbon-generating activities go on in the ocean. Living things that live in the ocean carry out photosynthesis by capturing CO2 from the atmosphere and converting it into organic matter.
Also, when these living things die, they decompose and organic matter is deposited into the ocean. It is a two-way process that takes CO2 from the atmosphere and retains it again.
Geological process
Some rocks and minerals can convert CO2 into carbonate compounds. This way, CO2 leaves the atmosphere and is fixed underground.
Artificial CO2 fixation
Man has developed technologies that trap CO2 from the atmosphere to help mitigate greenhouse gas emissions.
Direct air capture (DAC)
This technology of carbon capture is the direct removal of CO2 from the atmosphere via the use of chemical absorbents or filters.
The CO2 could be stored underground as batholiths, folds, mesas, or basalt. It could also be used for industrial processes such as fertilizer production, coal gasification, and processing of natural gas.
Bioenergy with carbon capture and storage (BECCS)
Biomasses are good energy sources. When they burn, they generate CO2. Rather than allowing this CO2 to go into the atmosphere, the BECCS technology captures and stores this CO2.
The process of carbon dioxide fixation
Natural or biological carbon dioxide fixation follows the process of photosynthesis. It is a step-by-step process that converts CO2 into glucose and oxygen. The process is as follows:
The light absorption stage
The photosynthetic process starts with the absorption of sunlight using chlorophyll present in plant cells.
CO2 capture
After the absorption of light, the stomata in the leaves absorb CO2 from the atmosphere and distribute it across plant cells. Aquatic plants take CO2 directly from the water body in which they live.
Conversion of CO2 to glucose
The conversion of CO2 takes place in the light-independent stage. CO2 reacts with the protons and electrons from the light-dependent reactions to produce glucose.
Release of byproducts
This is the last stage of photosynthesis which produces glucose and oxygen gas. It also involves the release of other organic compounds that are necessary for the survival of living things on Earth.
Significance of carbon dioxide fixation
Mitigation of climate change
As mentioned earlier, CO2 fixation reduces the amount of this greenhouse gas in the atmosphere. Natural and man-made CO2 fixation can help mitigate global warming.
The removal of CO2 and the conversion into organic compounds is a good way to put the gas to use even as it helps reduce extreme rises in global temperatures and the effects that come with it.
Low carbon economy
CO2 is a resource in the ecosystem. Artificial CO2 fixation technologies convert CO2 into biofuels and building materials.
These processes can further progress into a carbon-negative atmosphere. That is a situation whereby the methods involved capture more CO2 than is produced.
Ecological stability
The natural process of CO2 fixation helps to maintain a healthy ecosystem and support biodiversity. Artificial CO2 fixation technologies help to restore crumbling ecosystems. An environment that has lost its stability to deforestation can be restored by intentional afforestation.
Increased agricultural produce
The more CO2 in the atmosphere, the higher the plant growth and crop yield.
Are there any drawbacks?
Yes, there are drawbacks to carbon dioxide fixation. It could be quite challenging when you consider the cost of running the process on a large scale. Also, there are no long-term carbon storage methods yet. This makes it difficult to prevent the captured CO2 from going back into the atmosphere.
Furthermore, a lot of resources (other than money) must go into carbon dioxide fixation technologies. Lots of research and testing must be made for optimum results. This can be quite daunting and not many societies are willing to invest the time and money into it.
In addition, to maintain a stable and healthy environment, processes like afforestation and planting of bioenergy crops will take up land. This puts land needed for crop production and housing in competition with carbon dioxide fixation.
Is carbon fixation the same as the Calvin cycle?
Carbon dioxide fixation is a key step in the Calvin cycle. It is the first step of the Calvin cycle. This is the carboxylation step that converts a 5-C compound, ribulose-1,5-phosphate into a 6-C compound that further splits into two molecules of a 3-C compound, 3-phosphoglyceric acid (3-PGA).
The carboxylation of the 5-C to the 6-C compound is catalyzed by an enzyme called, ribulose-1,5-phosphate carboxylase/oxygenase (RuBisCO).
FAQs
Can carbon dioxide fixation occur at night?
Carbon fixation is the light-independent stage of photosynthesis but it can also occur during the day. Moreover, it is not completely light-independent because it requires the products of the light stage.
Is carbon dioxide fixation the same as photosynthesis?
Carbon dioxide fixation is the dark stage of photosynthesis. It does not require light but cannot work without the products of the light stage of photosynthesis. Carbon dioxide fixation is the process by which plants make their food.
What is the relationship between CO2 and cellular respiration?
CO2 is a product of cellular respiration. Carbon dioxide and energy are by-products of the breaking down of glucose and oxygen – the reactants of cellular respiration. The CO2 goes back into the atmosphere and becomes a product of photosynthesis.
What are plants called in carbon dioxide fixation?
The plants responsible for carbon fixation are autotrophs. There are two types of autotrophs: photoautotrophs and lithoautotrophs. Photoautotrophs use sunlight and lithoautotrophs use inorganic oxidation to fix carbon.
Conclusion
Carbon dioxide is a reactant of photosynthesis and a product of cellular respiration. It also plays a key role in mitigating climate change and the adverse effects of greenhouse gas emissions, thereby maintaining balance in the ecosystem.
From natural processes that take place in forests and oceans to carbon fixation by man’s influence, carbon fixation works to make the planet habitable for the present and future generations.
Want to learn more about the photosynthetic process? Here’s how to describe the process by its chemical equation.
Thanks for reading.