Fig. 2. Isotherms representing pesticide sorption by reference smectite clays (SWy-2 and SAz-1) and the corresponding humic acid (HA)-clay complexes. Sorption of 4,6-dinitro-o-cresol by (A) K-HA-SWy-2/K-SWy-2, (B) K-HA-SAz-1/K-SAz-1, sorption of dichlobenil by (C) K-HA-SWy-2/K-SWy-2, and (D) K-HA-SAz-1/K-SAz-1. The lines represent the predicted curves obtained by summing up individual and independent contribution of humic acid and smectite clays to pesticide sorption.