Precipitation of calcium carbonate in the presence of selected seawater constituents

Spontaneous precipitation of calcium carbonates in the presence of foreign ions, selected organic substances and suspended mineral particles was investigated. In the model system total initial concentrations of calcium and carbonate species, as well as the ionic strength, were similar to those in the seawater. Vaterite was the only phase precipitated from model system. The addition of magnesium and strontium slightly retarded precipitation, while the addition of fulvic acid inhibited the process almost completely. In contrast, the addition of montmorillonite caused almost instantaneous precipitation of calcite, indicating montmorillonite as the suitable substrate for the overgrowth of this polymorph.