Carbonate dissolution rates at the deep ocean floor

This paper reexamines experimental data on the seawater dissolution of CaCO3-bearing sediment beds to establish that the dependence of the calcite dissolution rate is linearly dependent on the calcite saturation state of the overlying water. This linearity is inherent to the original data and is not the result of an error in the solubility product for calcite. A comparison between these linear kinetics and the rate of solute transport across the benthic boundary layer further reveals that the overall rate of dissolution at ocean depths below the saturation horizon is controlled by boundary layer transfer. A carbonate mass-balance model for the sediment-water interface, which includes both kinetics and boundary layer effects, predictively reproduces the currently observed CaCO3 depth distribution for two test areas in the oceans. These findings allow important simplifications in modeling CO2 neutralization in the oceans. Citation: Boudreau B. P. (2013), Carbonate dissolution rates at the deep ocean floor, Geophys. Res. Lett., 40, 744-748, doi:10.1029/2012GL054231.