Sorption of polychlorinated biphenyls (PCB) to clay particulates and effects of desorption on phytoplankton

The sorption of polychlorinated biphenyls (PCB) on illite and chlorite, two minerals of defined composition, was investigated. Illite particles adsorbed higher [¹⁴C]PCB (Aroclor 1254) concentrations than did chlorite particles, with equilibrium concentration factors between particles and water being 1.4 × 10⁴ for illite and 1.0 × 10⁴ for chlorite. Desorbed PCB inhibited photosynthesis and reduced chlorophyll-a content of natural phytoplankton assemblages within dialysis membrane bags suspended in the water of a tidal marsh. There was no significant difference in effects on the phytoplankton of PCB desorbed from the two minerals. The rate of [¹⁴C]PCB desorption was dependent on the initial concentration on the clay particles. The rate of [¹⁴C]PCB loss from bags with particles was slower than that from bags without particles.