Fig. 3

Dolomite (left upper picture) and limestone (left lower picture) samples used in the autoclave experiments. Beside the sample, a computed tomography scan is shown. The red circle in the dolomite (upper pictures) marks rhombohedral dolomite crystals, and the green rectangle in the limestone (lower picture) marks a shell. CT images give insights to the reactive surface area which is necessary for dissolution. CT images were taken by Dr. M. Köhne/Prof. Dr. H.J. Vogel, UFZ. The Ca/Mg ratio was determined by acid digestion and ICP-MS analysis