How is a model of the carbon cycle different form the actual cycling of carbon in an ecosystem?
Answers
Answer:
The biological carbon cycle is not only faster than the geological carbon cycle. The amount of carbon taken up by photosynthesis and released back to the atmosphere by respiration each year is 1,000 times greater than the amount of carbon that moves through the geological cycle on an annual basis.
The biological carbon cycle plays a role in the long-term, geological cycling of carbon. The presence of land vegetation enhances the weathering of soil, leading to the uptake of carbon dioxide from the atmosphere. In the oceans, some of the carbon taken up by phytoplankton is used to make shells of calcium carbonate that settle to the bottom after the organisms die to form sediments. Marine animals, such as corals, also use dissolved carbon dioxide in biomineralization.
During the daytime in the growing season, leaves absorb sunlight and take up carbon dioxide from the atmosphere. Plants, animals and soil microbes consume the carbon in organic matter and return carbon dioxide to the atmosphere.
When conditions are too cold or too dry, photosynthesis and respiration cease along with the movement of carbon between the atmosphere and the land surface.
The amounts of carbon that move from the atmosphere through photosynthesis, respiration, and back to the atmosphere are large and produce oscillations in atmospheric carbon dioxide concentrations.
Significant amounts of carbon are stored in the biomass of forests and in the soil. Terrestrial sources release the stored carbon when forests are cleared for agriculture. Organisms in the ocean consume and release large quantities of carbon dioxide but ocean biological carbon cycles are faster than terrestrial cycles. There is virtually no storage of carbon as as biomass. Photosynthetic plankton are consumed by zooplankton within days to weeks.
Carbon dioxide exchange in the oceans is controlled by sea surface temperatures, circulating currents, and by the biological processes of photosynthesis and respiration. Carbon dioxide solvation is temperature dependent. Cold ocean temperatures favor the uptake of carbon dioxide from the atmosphere while warm temperatures can cause the ocean surface to release carbon dioxide. Cold, downward moving currents such as those that occur over the North Atlantic absorb carbon dioxide and transfer it to the deep ocean. Upward moving currents such as those in the tropics bring carbon dioxide up from depth and release it to the atmosphere.
Model carbon cycle:
A model of the carbon cycle is used to represent the global carbon cycle.
It has three reservoirs
- Atmosphere
- Biosphere
- ocean
It includes an exchange of carbon dioxide between reservoirs apart from the interior transfer within the ocean and biosphere.
Actual carbon cycle:
Nature reuses the carbon atoms, that travel from the atmosphere to the organisms on the earth and goes back to the atmosphere again. This process repeats over and over thus carbon atom remains constant.
In simple, the carbon cycle explains the process of carbon atoms exchange between the atmosphere and earth. Hence carbon atom remains sustained.
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