Carbon Cycle - Definition, Process, Diagram

Jul 24, 2023, 16:45 IST

Our biosphere is a stable ecosystem with constant interactions between the abiotic and biotic components. There is also a cyclic exchange of nutrients between these abiotic and biotic communities. This paves the way for biogeochemical cycles. The biogeochemical cycle is a process through which essential compounds circulate through the Earth’s abiotic and biotic compartments. Some of the most significant biogeochemical cycles are

1. Water Cycle
2. Nitrogen Cycle
3. Oxygen Cycle
4. Sulfur Cycle
5. Phosphorus Cycle
6. Carbon Cycle

Here, let us learn about the carbon cycle in detail.

What Is The Carbon Cycle?

Carbon is the most vital component of all organic molecules on Earth. They serve as the foundation for all living things. Carbon exists in various forms like diamonds, charcoal, and graphite. They can also be in the form of carbon dioxide, carbon monoxide, or even carbonate salts. The former are elemental forms whereas the latter are combined forms of carbon. This shows that carbon compounds are integral parts of our life and the presence, as well as the balance of carbon, are essential in our biosphere.

The exchange of carbon compounds between the earth's biosphere, hydrosphere, geosphere, pedosphere, and the atmosphere is known as the carbon cycle.

Steps Involved In The Carbon Cycle

Carbon is present in various places like the atmosphere, oceans, rocks, and sediments. Also, the different segments of the carbon cycle contain different types of carbon. In the atmosphere, they are present as carbon dioxide (CO₂). Carbon gets into the atmosphere via natural processes like respiration as well as industrial processes like the combustion of fossil fuels. This carbon is reabsorbed back via photosynthesis.

• Through the process of photosynthesis, the plants absorb atmospheric carbon dioxide to create carbohydrates which are converted into organic compounds like proteins, lipids, and polysaccharides.
• These polymeric organic compounds are subsequently transferred from plants to herbivores and carnivores.
• Plants and animals breathe out carbon dioxide, which is released into the atmosphere during respiration.
• Additionally, carbon dioxide is released into the atmosphere as a result of volcanic activity, combustion of fossil fuels, and decomposition of dead organic matter.
• Plants once again use this carbon dioxide in the process of photosynthesis to continue the carbon cycle.
• Thus photosynthesis, metabolism, and mineralization are the three important processes in the carbon cycle.

Carbon Cycle In Sea

Carbon is also found in the sea. In that, a small fraction is found as carbonate, particularly calcium carbonate. Animals including oysters, clams, certain protozoa, and some algae regularly employ this calcium carbonate to build their shells. The following three-step reaction happens when carbon dioxide and water react to form carbonate:

1. CO₂ + H₂O ⇋ H₂CO₃ (Carbonic acid)
2. H₂CO₃ ⇋ H⁺ + HCO₃^- (Bicarbonate)
3. H⁺ + HCO₃^- ⇋ 2H⁺ + CO₃^- (Carbonate)

Clams, for example, can make calcium carbonate by combining carbonate or bicarbonate with calcium that has been dissolved in the water. This calcium carbonate may either dissolve or stay in sedimentary form after the animal has passed away.

Carbon Cycle - Significance

We just saw how our life is built around this organic substance called carbon. However, do living creatures, produce their own carbon? No. This is the reason why carbon is cycled from different parts of the biosphere. These carbon compounds provide fuel energy, regulate our planet’s temperature, provide us with food energy, and also play a vital role in the global economy. Also, any imbalance in the carbon levels can create a serious impact on our planet. They can lead to serious problems like global warming and climate change. Thus by maintaining this carbon balance, the planet can support life indefinitely.

Human Influence On The Carbon Cycle

Carbon dioxide is a greenhouse gas that has the ability to warm up the Earth’s temperature. Human activities like deforestation and the burning of fossil fuels can increase the amount of carbon that enters the atmosphere. Thus they lead to global warming and result in the greenhouse effect. Also, man-made carbon compounds, new modifications in vegetation, and pollution alter the natural functioning of the biosphere. Thus they have the ability to disrupt the carbon cycle and amplify climate change.

Carbon cycle : FAQs

Q1. What are some key biogeochemical cycles?

Ans. The biogeochemical cycle is the process through which substances like oxygen, carbon, and water travels through the Earth's biotic and abiotic compartments. Some of the key biogeochemical cycles are - the water cycle, carbon cycle, oxygen cycle, sulfur cycle, nitrogen cycle, and phosphorus cycle.

Q2. Define the carbon cycle.

Ans. The carbon cycle is an important biogeochemical cycle in which the exchange of carbon between the biosphere, atmosphere, pedosphere, hydrosphere, and geosphere occurs.

Q3. What are some reservoirs of carbon?

Ans. Oceans are the biggest reservoir for carbon, followed by fossil fuel deposits in the earth's crust, terrestrial reservoirs (mostly plants and soil), and the atmosphere.

Q4. What are the 3 main processes that happen in the carbon cycle?

Ans. Photosynthesis, metabolism (excretion and respiration), and mineralization (decomposition) are the three important processes that happen in the carbon cycle.

Q5. Why carbon cycle is important?

Ans. Carbon is the fundamental building block of life on Earth. It provides us with energy and also regulates the Earth’s temperature. Also, a slight disruption in the cycle will have major consequences like global warming and climate change. Thus cycling of carbon is important.