Tenax extractions of legacy compounds, such as polychlorinated biphenyls (PCBs), provide a robust and rapid means of estimating bioaccumulation of sediment-associated contaminants.  Tenax extractions estimate bioaccumulation potential (bioavailability) by measuring desorption of these compounds from sediment from both laboratory and field exposures.  Therefore, Tenax extractions should also be useful for estimating bioaccumulation of other hydrophobic organic compounds of concern, such as pyrethroids.  However, pyrethroids provide unique problems compared to PCBs due to their continued introduction into aquatic systems and degradation in sediment and organisms, which can alter the bioavailability of these compounds in aquatic systems.  Single point Tenax extraction methods were used to determine the ability of Tenax extractions to correlate with the bioaccumulation of pyrethroids by benthic invertebrates exposed to various experimental conditions.  Three sediments, ranging in organic and black carbon content, were dosed with one bifenthrin concentration, and aged for 7, 14, 28, and 98 d.  Bioaccumulation assays and 24 h Tenax extractions were performed with all sediments after each aging time, and a single linear relationship (p <0.0001) with a constant slope and intercept was established between the Tenax extractable concentrations and parent tissue concentrations of Lumbriculus variegatus for each sediment.  This relationship was observed after a 28 d aging period, suggesting equilibrium as not reached until this point.  The data of the current study were combined with that of previous work comparing Tenax extractions of bifenthrin and permethrin to tissue concentrations of L. variegatus and Hexagenia sp.  The combined data resulted in a single log linear relationship (p <0.0001) between 24 h Tenax extractable and tissue concentrations.  This relationship provides a preliminary model for estimating exposure of benthic invertebrates to pyrethroids in aquatic sediments.  This model is now available for testing the accuracy of pyrethroid exposures from a wide range of field-contaminated sediments.

Development of a Tenax model to predict bioavailability of pyrethroids in sediment

248th National Meeting (2014)

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