We observe a strong kinetic effect on Ca incorporation in aragonite. This effect is observed in both inorganic aragonite and in corals. As the rate of precipitation increases the isotope fractionation decreases (44Ca/40Ca). At high precipitation rates above ~104.0 μmol·m-2·h-1 the fractionation becomes constant in a minimum fractionation point. Since corals calcify at high rates of 103.9 μmol·m-2·h-1 and above, no rate effect on Ca isotopes fractionation is expected. Ionic strength appears to have insignificant effect on Ca incorporation of inorganic aragonite. We hypothesize that Ca isotope fractionation in corals is controlled by the saturation state in the extracellular fluid and the rate of calcification
