Fig. 4. Column effluent composition of Soil 4. (a) Preconditioning with 10^-5 M CaCl₂ and leaching of Ca-exchangeable metals with 10^-2 M CaCl₂ solution (pH 6). An effluent volume of 1 mL/g corresponds to approximately 1.6 pore volumes. (b) Leaching with 10^-2 M CaCl₂ adjusted to pH 3.0. An effluent volume of 1 mL/g corresponds to approximately 1.1 pore volumes. The first 100 mL/g corresponded to the same leaching sequence as in (a).