Fig. 3. Apparent distribution coefficients (K_d) for sorption of naphthalene and/or pyrene to minerals saturated by different cations: (a) naphthalene/silica gels (pore sizes of 60 and 150 Å), (b) pyrene/silica gels (pore sizes of 60 and 150 Å), and (c) pyrene/kaolinite (kaol), and pyrene/vermiculite (verm) (Na-kaol, Cs-kaol, Na-verm, and Cs-verm data from Grimaldi [1999]).