Crystallization of the (Cd,Ca)CO₃ solid solution in double diffusion systems: the partitioning behaviour of Cd²⁺ in calcite at different supersaturation rates Available to Purchase

Considering an ideal solid solution, the partitioning of cadmium in calcite was studied at different levels of supersaturation (δ) using counter-diffusion experiments. The effective (non-equilibrium) distribution coefficients of Cd²⁺ in calcite (D_Cd), varied between 20 and 100 depending on the initial concentration of reactants and the evolution of supersaturation. A function that relates the D_Cd with the supersaturation at nucleation was derived: logD_Cd = −0.40logδ + 2.42. The relationship obtained suggests that in natural waters, Cd²⁺ can be incorporated to a greater degree in calcite when the solid solution-aqueous solutions system is near to equilibrium, which can occur in scenarios where the supersaturation rate and hence the supersaturation level are relatively small.