New advances in passive sampling to measure freely dissolved concentrations and linking with bioaccumulation models for sediment risk assessment

Abstract

While hydrophobic pollutants like polychlorinated biphenyls (PCBs) bind strongly to sediments, the process of uptake in aquatic organisms is controlled by an aqueous pathway. Measuring the freely dissolved concentrations of PCBs is challenging due to the very low concentrations and association with suspended particles. Recent advances in passive sampling have made it possible to accurately measure freely dissolved concentrations of bioaccumulative pollutants in water. This presentation provides an overview of the science behind passive sampling and new guidance documents that have been published recently. The criteria for selection of a passive sampling approach is discussed and include clear delineation of measurement goals, whether laboratory-based “ex situ” and/or field-based “in situ” application is desired, and ultimately which sampling method is best suited to fulfill the measurement objectives. Guidelines are provided for proper calibration and validation, including use of provisional values for polymer–water partition coefficients, determination of equilibrium status, and confirmation of nondepletive measurement conditions. Finally, results of the application of passive sampling in a case study involving the prediction of bioaccumulation in fish before and after sediment remediation is presented.