BIOACCUMULATION OF PCBS BY ALGAE - KINETICS VERSUS EQUILIBRIUM

The objectives of this study were to test the hypothesis that bioaccum ulation of hydrophobic organic compounds (HOCs) by phytoplankton is co rrelated to the compound's octanol/water partition coefficient (K(ow)) in a predictive relationship in laboratory experiments, and to confir m these findings with field observations. In laboratory experiments we measured the uptake of 40 representative polychlorinated biphenyl (PC B) congeners over time under conditions that inhibited and allowed phy toplankton growth. Results indicated that the bioaccumulation process is consistent with partitioning from water into cell lipids but is slo wer than previously thought. The uptake of PCBs was slow relative to g rowth of phytoplankton, preventing the chemical from reaching thermody namic equilibrium in algal cells under conditions promoting growth (no nwinter). Thus under nonwinter field conditions, many PCB congeners ne ver reach equilibrium concentrations. Food-chain models that assume eq uilibrium between HOCs and the primary trophic level could be inaccura te and may need to use a kinetic framework.