Carbonate compensation dynamics

Carbonate saturation (z(sat)) and compensation (z(cc)) depths change with deep-ocean acidification and basification. We present simple, explicit, mechanistic formulas for the positions of these two critical depths. In particular z(cc) is expressed as a function of the mean dissolved carbonate ion concentration of the deep ocean, [CO3](D), the supply of dissolvable CaCO3, F-c, and the dissolution rate constant at the sediment-water interface, k(c), which we show to be essentially mass-transfer controlled. Calculations reveal that z(sat) and z(cc) are today some similar to 0.9 km apart and will rise and separate by as much as 1.7 km with acidification; conversely, if [CO3](D) increases, z(sat) and z(cc) will deepen, but their separation will asymptote to similar to 0.7 km. Citation: Boudreau, B. P., J. J. Middelburg, and F. J. R. Meysman (2010), Carbonate compensation dynamics, Geophys. Res. Lett., 37, L03603, doi:10.1029/2009GL041847.