9530762 Coale 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 three- year 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. This component concerns the effect of iron on the productivity of the upper layers of the ocean. Dissolved iron concentrations in surface waters of the open ocean are often extremely low, and have been shown to limit primary production in high nitrate and low chlorophyll regions of the global ocean. As a result of an earlier JGOFS study in the equatorial Pacific Ocean, models describing the spatial and temporal variability in production and export now include the role of iron as a limiting micronutrient. The observed patterns of production in the equatorial Pacific were consistent with the supply and distribution of iron in this region. However, there are very little data on iron concentrations and distribution of iron in the Southern Ocean that could be used for such interpretations. For example, we do not know if iron concentrations are enhanced or depleted in Southern Ocean upwelled waters. Also, very little information is known concerning the concentrations, distributions, or sources of iron in the Southern Ocean and as a result, it is currently difficult to correlate patterns of productio n in these waters with the distribution of iron. Systematic measurements of trace metal distributions in the Ross Sea and in the Antarctic Polar Front Zone with an emphasis on iron will be made as part of this study, and will provide a data base that will allow the evaluation of Southern Ocean biological processes in terms of a possible iron limitation. The results of this work will be a significant contribution to our understanding of iron biogeochemistry in the Southern Ocean, and to our understanding of factors which control rates of new production in these regions. They will have a direct bearing on our understanding of the global carbon cycle. ***
