Research is underway to study the dissolution of calcium carbonate particles on the ocean floor. The laboratory diffusion-cell study is designed to determine the effective diffusion coefficients of the dissolved carbonate species sediments. This effort will help to determine whether the dissolution rates are limited by diffusive exchange between seawater and pore waters or by reaction kinetics. The field experiment is designed to determine rates of recycling of benthic organic carbon and calcium carbonate carbon above and below the calcite saturation horizon in the western equatorial Atlantic Ocean. A primary goal of the research is to determine to what extent the dissolution is enhanced by the oxidation of organic matter within surface sediments. In situ high resolution pore water profiles of pH and pCO2 will be made using newly perfected microelectrode techniques. The field work is planned for the Ceara Rise area in conjunction with benthic chamber flux measurements by R. Jaknke and with in situ whole core squeezer methods by Martin and Sayles. Preliminary testing and intercomparison of methods is being done in the southeastern U.S. continental margin.
