We developed a novel non-equilibrium passive sampling method to determine the freely dissolved concentrations (Cfree) of hydrophobic organic contaminants in sediments using polyethylene (PE) with multiple thicknesses. Uptake kinetics of polychlorinated biphenyls (PCBs) in quiescent sediment was closely examined in sediment microcosms. The observed results using PE with thicknesses of 17, 51, and 102 μm were fitted with three models, a first-order model, a 1-D diffusion model with a sediment diffusion related parameter determined by sediment distribution coefficients and porosity, and the 1-D diffusion model with the parameter determined by best-fit curves of the modeling results with experimental data. Among the three studied models, the 1-D diffusion model with the fitted parameter best described the observed PCB uptake kinetics. The uptake kinetics from sediment to PE for sediment-derived PCB congeners was generally slower than the release kinetics from PE to sediment for PCB congeners initially embedded into PE prior to exposure. This suggests that the isotropic exchange kinetics assumed for the application of performance reference compound (PRC)-based methods may not be valid in some cases. The novel non-equilibrium passive sampling method using PEs with multiple thicknesses gave estimates of PCB Cfree in the study sediment within a factor of three difference compared to the values measured by equilibrium PE sampling in a slurry phase experiment. This study suggests a potential of the novel PE sampling method to estimate the Cfree for hydrophobic organic contaminants in sediment when the assumption of isotropic exchange kinetics is not valid.

Development of a novel non-equilibrium passive sampling method using polyethylene with multiple thicknesses

251st National Meeting (2016)

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