Carbon dioxide (CO2) concentration in the ocean changes with depth due to various physical and biological processes. Based on specific oceanic regions, particularly polar areas, one significant way CO2 impacts deeper waters is through the sinking of carbon-rich surface water.
The Role of Polar Regions in Deep Ocean Carbon Transport
In polar regions, the solubility of carbon dioxide in cold water is high. This allows the surface water to absorb a significant amount of atmospheric CO2, becoming carbon-rich.
A key mechanism driving CO2 from the surface to the deep ocean in these areas is the formation of dense water. As the reference explains: The colder and more saline the water is, the deeper it sinks, taking the dissolved carbon with it to greater depths.
This process is crucial for the physical pump, transporting carbon from the surface mixed layer into the deeper ocean layers.
Impact on Deep Ocean CO2 Levels
The sinking of this dense, carbon-rich water directly influences the CO2 concentration at greater depths. It acts as a continuous transport mechanism, moving dissolved inorganic carbon from the surface reservoir to the vast deep-ocean reservoir.
This transport contributes to the generally higher concentrations of dissolved inorganic carbon found in the deep ocean compared to the surface in many parts of the world. The carbon accumulated over long timescales at depth includes carbon delivered by this process as well as from the decomposition of organic matter sinking from above (the biological pump).
In summary, while the overall profile of CO2 with depth can vary by location and other factors, the sinking of cold, saline, carbon-rich water, particularly in polar regions, is a direct way carbon dioxide is transported to and affects concentrations at greater depths.
