Fig. 6. Column effluent composition of Soil 4 during leaching with CaCl2 solutions adjusted to pH 3. (a) Experiment with a low Ca influent concentration of 10-5 M (an effluent volume of 1 mL/g corresponds to approximately 1.5 pore volumes). (b) Experiment at low flow rate of 0.05 mL/min (an effluent volume of 1 mL/g corresponds to approximately 1.2 pore volumes).