SEDIMENTARY CALCIUM-CARBONATE DISSOLUTION IN THE GULF OF THAILAND ANDITS ROLE AS A CARBON-DIOXIDE SINK

Seven sediment core samples were collected from the upper Gulf of Thai land in the western Pacific Ocean. Analyses of pore-water for total al kalinity, dissolved inorganic carbon, and dissolved calcium concentrat ions revealed that there existed CaCO3 dissolutions in the upper 1 met er of the sediment. The absolute magnitude of the CO2 sink due to CaCO 3 dissolution was possibly an order of magnitude smaller than the CO2 produced by the net CaCO3 precipitation and also about one order of ma gnitude less than CO2 sequestered by the net burial of organic matter by the sediment. Sulfate reduction that coupled with authigenic solid sulfide phases formation was proposed as a possible mechanism that mig ht help retaining CO2 in the pore-water. More work is being done to ri nd out more on the carbon-sulfur system in the Gulf of Thailand sedime nt.