Rates of Calcium Carbonate Dissolution and Organic Carbon Decomposition in the North Pacific Ocean

Abstract

Recent carbonate data collected in the North Pacific were combined with the data in the literature in order to understand more clearly the carbonate chemistry in the North Pacific. Our analyses show that inorganic CaCO₃ dissolution contributes about 26% of the total inorganic CO₂, increase of deep water, after leaving the Southern Ocean. The calcium and alkalinity data indicate a CaCO₃ dissolution rate of 0.060±0.010 and 0.053±0.005 μ mol kg^-1 yr^-1 respectively, for waters deeper than 2, 000m in reference to the Weddell Sea Deep Water. The organic carbon decomposition rate is 0.107±0.012 ± mol kg^-1 yr^-1 while the oxygen consumption rate is 0.13± 0.002 μ mol kg^-1 yr^-1. These results which are based on the direct comparison of two water masses agree well with other estimates which are based on methods such as the one-dimensional-diffusion-advection model. Comparison of data along the two sections at 165°E and 150°W shows no significant difference in the ratio of the CaCO₃ dissolution rate and the organic carbon decomposition rate. The eastern section, however, has a higher TCO₂ input than the western section because of the older age of the deep water along the eastern section.