Carbon Cycling: What Does It Mean?

When you take a biology class, there are many cycles that you teacher will discuss in class. There’s the cell cycle, the nitrogen cycle, the water cycle, and other nutrient cycles such as the carbon cycle. Carbon cycling is a vital process for maintaining the ecosystem as all biomolecules contain carbon in some shape or form, without which life would not exist as we know it.

Carbon Cycling: What Does It Mean?

As seen in this carbon cycling diagram, the carbon travels through multiple media within the earth. In carbon cycling, the carbon will travel through plants, animals, microbes, and bodies of water, as well as through the atmosphere. These media are also known as carbon sinks. Carbon sinks are responsible for absorbing carbon. The other agents present in the carbon cycle are carbon sources. A carbon source is responsible for releasing carbon into the atmosphere. The interaction between sources and sinks contributes to the key processes of carbon cycling.

Key Processes in Carbon Cycling

1. Carbon enters the atmosphere as carbon dioxide- The most common form of carbon is carbon dioxide, which happens when carbon is attached to oxygen. This carbon dioxide is then absorbed by plants for further utilization.
2. Carbon dioxide facilitates the process of photosynthesis- Carbon dioxide is taken in, along with water to create glucose and oxygen. The production of glucose creates a food source which allows the plants to grow their stems and leaves. Plants, especially trees, are major carbon sinks as they absorb large amounts of carbon dioxide from the atmosphere to continue undergoing photosynthesis.
3. Carbon moves along the food chain- Carbon found in the plants is consumed by plant eating organisms, which are in turn consumed by carnivores, which can be apex predators. According to the concept of biomagnification, in order to have the same energy output, as more of an organism is consumed, meaning more of the included elements in it are consumed, whether plants or animals, there will be a higher concentration of the nutrients and elements present in the top of the food web. Since carbon is present in all the bio molecules, its concentration increases.
4. Carbon Dioxide Also Comes From Decomposition- When plants and animals die, they decompose into the soil. Over extended periods of time, layers of sediment stack on top of the decomposed material. As these layers build up, the pressure and heat from the Earth’s crust turn those decomposed materials into fossil fuels. This occurs because of anaerobic decomposition which involves bacteria breaking down carbon compounds like glucose into carbon dioxide and oxygen.
5. Carbon Dioxide is Released Through Respiration- When humans and other animals conduct respiration, they intake the oxygen in the atmosphere and release carbon dioxide. This is then taken up by plants and other reservoirs.
6. Carbon Is Released Through Combustion- When fossil fuels are extracted from the earth, they are then utilized to power cities and cars. A byproduct of combustion is carbon dioxide, and its accumulation contributes to an increased concentration of greenhouse gasses. This is a carbon source that mainly stays in the atmosphere, but a small portion of it will dissolve into the ocean.
7. Carbon Is In The Ocean- The carbon dioxide moves from the atmosphere into the ocean. The ocean will absorb this carbon and dissolve it into the seawater.
8. Carbon On The Rocks- Carbon also enters the ocean from rocks, which can be released due to weathering, leading to runoff flowing into the ocean.
9. Carbon Leaves The Sea- Carbon is taken out of the ocean when the shells and bones of sea creatures accumulate along the ocean floor. They are composed of a material known as limestone, which also has carbon. This carbon is sequestered from the rest of the carbon cycle. It can be released back if the limestone melts.

Why Should We Care About Carbon Cycling?

The carbon cycle allows life on earth to exist. Nature on its own has all these processes occurring so that a balance exists between carbon absorbed and carbon released. However, there is now a degree of imbalance in the carbon cycle because since the Industrial Revolution, more carbon has been released into the environment, increasing the concentration of greenhouse gasses in the atmosphere. Deforestation is contributing to a decrease in carbon sinks and the increased absorption of carbon in the ocean has led to the oceans becoming warmer as well. This has significant ramifications on the ocean ecosystem as well. In short, the carbon cycle allows for many diverse ecosystems to exist and keeping it balanced will keep these diverse ecosystems existing for many years to come.

 

Author: Maaida Kirmani