Fig. 6. Measured - calculated (from total alkalinity and pH) dissolved inorganic carbon vs latitude for A17.
This trend and offset appears to be an artifact of the dissociation constants used in the calculations. This trend was not observed by Rios and Perez, who used slightly different dissociation constants. (Rios, A. F., and F. F. Perez. 1999. Improvements in potentiometric determinations of the CO₂ oceanic system using substandards and CO₂ reference materials. Ciencias Marinas 25: 31-49.)