Application of a Tenax model to assess bioavailability of polychlorinated biphenyls in field sediments

Recent literature has shown that bioavailability-based techniques, such as Tenax extraction, can estimate sediment exposure to benthos. In a previous study by the authors, Tenax extraction was used to create and validate a literature-based Tenax model to predict oligochaete bioaccumulation of polychlorinated biphenyls (PCBs) from sediment; however, its ability to assess sediment remediation was unknown. The present study further tested the Tenax model by examining the impacts of remediation on surface sediment concentrations, Tenax extractable concentrations, and tissue concentrations of laboratory-exposed Lumbriculus variegatus. Tenax extractable concentration was an effective exposure metric to evaluate changes in Lumbriculus exposure preremediation and postremediation, with 75% of the postremediation data corresponding to the Tenax model. At nondredged sites, bioaccumulation was better predicted by the Tenax model, with 86% of the data falling within the 95% confidence intervals, than at dredged sites, for which only 64% of the data fit the Tenax model. In both pre- and postdredge conditions, when the model failed, it was conservative, predicting higher PCB concentrations than observed in the oligochaetes, particularly for the postdredge data. The present study advances understanding of the applicability of the Tenax model for use when examining systems that may have undergone significant disturbances. The Tenax model provides a unique tool for quickly quantifying potential exposure to benthic organisms.