Fig. 6. Relationship between the octanol–water partition coefficient (log K_ow) value of the compounds (Mackay et al., 1992; Hawker and Connell, 1988) and the concentration ratio between the individual polycyclic aromatic hydrocarbons (PAHs; top) and polychlorinated biphenyls (PCBs; bottom) in the preferential flow paths and in the matrix of the A horizon (0 to 9 cm).