Calcium Carbonate Saturation in Northeastern Pacific: In Situ Determination and Geochemical Implications

In situ measurements by calcite and aragonite saturometry in the intermediate waters of the northeastern Pacific, indicate that these waters are close to saturation with respect to calcite. It is proposed that the carbonate compensation depth in this region is mainly controlled by the degree of carbonate saturation of ocean waters. If this suggestion is correct, then the carbonate compensation depth can be shown to be directly related to the alkalinity and nutrient cycles in the oceans. Three independent factors seem to control the depth of carbonate compensation: bottom topography, nutrient recycling rate (oceanic mixing) and a dependency factor relating biogenic CaCO₃ production to nutrient availability.