1. The effect of a carbonate sink on the isotopic composition of soil CO2
Jonathan G. Wynn & Jennifer Chelladurai, Department of Geology, University of South Florida, Tampa, FL
Keeling plot model of diffusion-production-equilibrium of respired with atmospheric CO2:
We modified the boundary conditions of the Cerling (1984) diffusion-production-equilibrium model of soil CO2 to account for a 13C-enriched sink of soil carbonate:
Synthetic soil profiles incubated with C3 and C4 litter show [CO2] and 13C values inconsistent with diffusional mixing of heterotrophically-respired CO2 with atmospheric CO2(solid black lines). Our data are consistent with our modified model including a sink of 13C-enriched CO2 at in “developing Bk” horizons (red dashed lines).
Cerling, T. E The stable isotopic composition of soil carbonate and its relationship to climate. Earth Planet. Sci. Lettr. 71, 229–240.