Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility

Abstract : The goal of the laboratory demonstration effort is to develop and standardize a procedure using field deployable solid phase micro extraction (SPME) for the measurement of freely-dissolved pore water concentrations and demonstrate the relationship of these measurements to contaminant flux, bioavailability and bioaccumulation. Pore water concentrations drive contaminant fluxes below the biologically active layer and in contaminated sediment caps a method for easily determining these levels provides a better means of evaluating contaminant migration and release. More importantly, direct measurement of that portion of the contaminant that is freely dissolved has been shown to be an effective tool for determining the bioavailable fraction and predicting bioaccumulation of simple partitioning contaminants. Even tissue concentrations of bioaccumulative contaminants can often be related to pore water concentrations. SPME has traditionally been used for the determination of aqueous phase concentrations but work in the laboratory has shown that it can be used for in situ determination of pore water concentrations if appropriately armored and strengthened and if sufficient time is provided for equilibration. The project is designed to determine and demonstrate the optimum approach to implementation of SPME for in situ determination of pore water concentrations and bioavailability of PAH and PCB in sediments. The goal is to move SPME from a laboratory approach to a routine field characterization tool.