Fig. 1.

A diagram of the assumed exchange of inorganic carbon isotopes with water used in the mathematical simulations and modelling described herein. ${\mathrm{P}}_{{\text{HCO}}_{3^{-}}}$, ${\text{HCO}}_{3^{-}}$ permeability of chloroplast; $P_{{\text{CO}}_2}$, CO₂ permeability of chloroplast; k_h, CO₂ hydration rate constant; k_d, ${\text{HCO}}_{3^{-}}$ dehydration rate constant; CA, scaling factor of carbonic anhydrase activity. As the loss of ¹⁸O from Ci species is the key component of measurements, ¹⁸O is labelled in red. Ci species measurable in the mass spectrometer are in bold, and mass over charge value (m/z) specified. ¹³C-labelled inorganic carbon is used for all assays.