The role of Mg2+ in inhibiting CaCO3 precipitation from seawater

Abstract The precipitation and dissolution processes of CaCO3 are essential to the marine carbon cycle and are relevant to climate research. Nevertheless, one of the nagging questions is why the precipitation of CaCO3 rarely occurs without the help of biological activity even in the surface seawater, where the calcite saturation state (Ω, expressed as the ratio of the calcium and carbonate ion concentration product to the stoichiometric solubility constant of calcite) is up to 5, but commonly takes place in hard-water lakes, springs and the low-salinity zone (practical salinity