The Carbon Dioxide System in the Southern Ocean

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9530384 Millero This research project is part of the US Joint Global Ocean Flux Study (JGOFS) Southern Ocean Program aimed at (1) a better understanding of the fluxes of carbon, both organic and inorganic, in the Southern Ocean, (2) identifying the physical, ecological and biogeochemical factors and processes which regulate the magnitude and variability of these fluxes, and (3) placing these fluxes into the context of the contemporary global carbon cycle. This work is one of forty-four projects that are collaborating in the Southern Ocean Experiment, a threeyear effort south of the Antarctic Polar Frontal Zone to track the flow of carbon through its organic and inorganic pathways from the air-ocean interface through the entire water column into the bottom sediment. The experiment will make use of the RVIB Nathaniel B. Palmer and the R/V Thompson. It is known that the flux of gaseous carbon dioxide from the atmosphere to the ocean is controlled by the airsea difference in the partial pressure of CO2. In the ocean the dissolved carbon dioxide is in chemical equilibrium with the carbonate and bicarbonate ions. The carbonate ion concentration controls the rate of dissolution and precipitation of calcium carbonate, and the rate at which inorganic carbon is delivered to the sediment. What is not known very well is how these inorganic relationships are affected by biological processes in a region where production and transformation processes are quite large. This component concerns the direct measurement of the carbonate system on seven cruises between 1996 and 1998. This will involve measuring total inorganic carbon dioxide (TCO2), the partial pressure of gaseous carbon dioxide (pCO2), and total alkalinity (TA) in the surface waters, as well as the pCO2 in atmosphere, continuously along the cruise tracks. Complementary depth profiles of the oceanic parameters will be made at some of the stations. These measurements will be made in cooperation with the carbon-related measurements planned by other groups that receive support to participate in the experiment. The resulting carbon-based and nutrient measurements should provide the necessary field data that will be required in examining the flux of carbon dioxide across the air-sea interface and the changes resulting from primary productivity and the oxidation of plant material. ***