| Summary: | The oceans play a critical role in regulating the global carbon cycle. eep-ocean waters are roughly 200% supersaturated with CO2 compared to surface waters, which are in contact with the atmosphere. his difference is due to th flux of photosynthetically derived organic material from surface to deep waters and its subsequent remineralization, i.e. the "biological pump". he pump is a complex phytoplankton-based ecosystem. t is driven by sunlight, and fueled by the supply of inorganic nutrients derived primarily from the deep ocean. n areas of the oceans where inorganic N and P are effectively exhausted by phytoplankton in surface waters during the growing season, the pump functions at maximal efficiency. he transport of carbon to depth is limited by the flux of N and P into the surface waters. n the Southern Ocean, near the equator, and in the subarctic Pacific, however, relatively high concentrations of nitrate and phosphate are found in the surface waters throughout the year, and phytoplankton biomass and net production are much lower than would be expected based on the availability of major nutrients. hus in these areas of the ocean the biological pump appears to be operating at less than maximal efficiency. onsequently, these regions are receiving increased attention, not only as they relate to global biogeochemical cycles, but also as potential sites for anthropogenic enhancement of CO2 flux into the ocean. he economic, social, and ethical concerns surrounding such a proposition, along with the outstanding scientific issues, call for rigorous discussion and debate on the regulation of productivity in these regions.
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