Discrepant Ca and Alkalinity Distributions in the Oceans - Its Relevance to Deep Ocean Chemistry and a Test of the Hydrothermal Hypothesis

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9529749 Nelson The chemistry of calcium and the carbon dioxide-carbonate system of the world ocean are intimately related by processes of production and dissolution of calcium carbonate. The calcium carbonate- carbon dioxide system is in fact one of the major geochemical features of the marine environment. Recent data strongly suggest that variations in calcium concentrations in the ocean are not quite equal to those one would expect based on the corresponding variations in alkalinity. This means that there is something about this major marine geochemical system that we do not understand. In this project, scientists at the University of Washington will carry out a detailed study of calcium and alkalinity variations in the oceanic water column with two ends in mind. First they will characterize the calcium-alkalinity discrepancy on a global basis by surveying waters of the Northwest Pacific, Northeast Pacific, Southeast Pacific, and the North Indian Ocean. Secondly, they will also make high-precision measurements of magnesium and lithium concentrations and lithium isotope distributions on a global scale to test the hypothesis that the Ca- alkalinity discrepancy can be explained by hydrothermal input of ocean ridges.