Ocean and Terrestrial Carbon Amounts

Soil contains molecular carbon, carbon of organisms living in the soil, and detritus (broken parts of dead plants, corn stalks, and tree leaves, etc.) in total amount of about 1200 units. This suggests that the soil contains about twice as much carbon as the terrestrial biology. The ocean presents a more complicated problem for evaluating carbon stores and fluxes. The deep ocean has about 34,000 units, and the surface ocean has about 600 units in what is considered the warm ocean and 300 units in the cold ocean. It should be noted that the deep ocean has a very large reservoir of carbon, but essentially it is stored there permanently, since the cycling time from the deep ocean is on the order of hundreds to thousands of years. The ocean also receives carbon from inorganic carbon transported from continental areas by rivers.

Near the ocean surface, turbulent motions promote the uptake of atmospheric carbon dioxide by the ocean through the formation of weak carbonic acid. Approximately 22 units per year go from the cold ocean into the atmosphere, and about 35 units come back, making the cold ocean a net sink for carbon dioxide from the earth's atmosphere. The warm ocean, by contrast, is a net source because it is emitting 80 units and taking in only 70, giving a net flux outward of about 10 units. CO₂ in the deep ocean is essentially disconnected from the carbon cycle because it would take 1000s of years to cycle to the surface. The deep ocean has been suggested as a burial ground for CO₂ from power plants.

Terrestrial (land) biology consumes about 110 units per year, mostly in support of terrestrial plant growth. About 50 units of that goes back into the atmosphere in the decay process, and about 60 units goes into the soil. The soil, it turn, releases about 60 units back to the atmosphere, resulting in a balance of fluxes in and out of the natural terrestrial biological system.

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