The Carbon Cycle

The Carbon Cycle is a major component of the Biogeochemistry of the planet. Across the Lithosphere and Biosphere, carbon plays a large role in the creation of biomass as well as decomposition. The carbon cycle in the hydrosphere, particularly in the oceans, is not as well known. We do know, however, that oceans play a critical role in the carbon cycle because it acts as a large sink of carbon as it is rapidly exchanged with the atmosphere. The carbon cycle in the oceans involves both organic compounds and inorganic compounds. The distribution of these carbon forms are then largely controlled by the Solubility and Biological Pumps.

The Solubility Pump works because of the fact that CO2 is more than twice as soluble in cold water than warm water. This allows carbon to be removed from the atmosphere at the poles, and then pumped into the deep ocean that contains this similar cold, high-density water. The Biological Pump is driven by the biota in the oceans. When CO2 is absorbed from the atmosphere into the oceans it is converted into Dissolved Inorganic Carbon (DIC). At the ocean’s surface, the primary production of marine phytoplankton then converts this DIC into organic material. Certain phytoplankton also have the ability to combine dissolved calcium with dissolved carbonate to create Calcium Carbonate (CaCO3). This calcium carbonate is used to make up the hard shell coatings of many marine organisms from small plankton such as coccolithophores and phytoplankton, to larger organisms such as mollusks, crustaceans, and echinoderms. The biological pump can mostly be explained as the cycling of these organisms and their shells. When an organisms dies, the fixed carbon from its soft or hard tissue is mostly contained in the upper lev...

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...on of drawing CO2 from the atmosphere into the deep oceans. As always, much more research needs to be done on this CO2 removal option and better determine the positive and negative effects.

It has been proven that the carbon cycle is essential to the Earth’s Biogeochemical cycles, but much is still to be learned about the processes that go on in the Earth’s oceans. Whether it be through natural transference from the atmosphere, or anthropogenic pumping, the CO2 levels in the oceans are increasing. Many studies have taken place to try and understand the effects that this increase will have on oceans and its biogeochemical cycling, and most have proven to be negative. These negative effects, such as dissolution of calcium carbonates and hypercapnia on water breathing organisms, can have long term effects on populations, species and the overall food web of the ocean.