A Model System to Study the Desorption and Biological Availability of PCB in Hydrosoils

Abstract

Model aquatic systems incorporating hydrosoil, water, and fish components were used to measure the dynamics of Aroclor 1254 [polychlorinated biphenyl (PCB)] under both flowing and static water conditions. PCB desorption from hydrosoils was consistent with adsorption-desorption theory. Under static conditions, hydrosoil PCB concentrations from 10 to 500 µg/g produced equilibrium levels of 0.13 to 7.60 µg/litre PCB in water. In continuous flow tests, equilibrium PCB levels in water ranged from 0.11 to 0.54 µg/litre for hydrosoil concentrations of 100 to 500 µg/g PCB. Equilibrium PCB concentrations in water could be predicted under both static and continuous flow conditions with the distribution coefficient equation. Desorption favored the lower-chlorinated, more water-soluble components of Aroclor 1254. Fathead minnows allowed direct contact with PCB-contaminated hydrosoils accumulated PCB residues at six times the rates of those screened from direct exposure to sediments. Fish selectively bioaccumulated the higher chlorinated components of Aroclor 1254.