Nonlinear and interactive effects in the sorption of hydrophobic organic chemicals by sediments

Long-term experiments were done in order to investigate nonlinear isotherms and interactive effects in the sorption of hydrophobic organic chemicals ( HOCs) by sediments. In the isotherm experiments, it was demonstrated that t he isotherms for all HOCs tested were linear as long as the mass of the sor bed HOC was small by comparison with the mass of organic carbon in the sedi ments; for larger sorbed HOC concentrations, the isotherms were nonlinear. Sorption experiments also were done with hexachlorobenzene (HCB)-octanol, H CB-ethanol, octanol-ethanol, and HOC-methanol mixtures in water and sedimen ts. Interactive effects were observed and can be described in terms of the partitioning of the primary HOC between the cosolvent, water, and sediments .