| Fugacity is a useful tool for measuring the partitioning behaviour and dynamics of sediment-associated chemicals, and may provide a better indication of contaminant bioavailability than concentration. We present a method, based on thin film solid phase extraction techniques, to measure the fugacity of hydrophobic organic contaminants in sediment. The method involves placing sediment in vials coated with the solid phase extracting medium, ethylene vinyl acetate (EVA). When equilibrium is reached, the fugacity in the sediment (fs) is equal to that in the EVA, and fEVA can be determined using the EVA concentrations (CEVA) and fugacity capacities (Z EVA). Equilibrium EVA concentrations were determined using a two-compartment uptake model fitted to the measured EVA concentrations over time. ZEVA was estimated using the test chemicals' octanol-air partition coefficients (Koa). We believe that this method provides a simple and relatively rapid means to approximate chemical bioavailability in sediment. (Abstract shortened by UMI.)... |
