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(522) Application of thin-film solid phase extraction to measure fugacity and fugacity capacity of organic contaminants in sediments .
Otton, Victoria*,1, Meloche, Lizanne1, Kozma, Melissa1, Birch, Gavin2, Gobas, Frank1, 1 Simon Fraser University, Burnaby, BC, Canada2 University of Sydney, Sydney, Australia
ABSTRACT- Solid-phase extraction using thin films of ethylene vinyl acetate (EVA) coated onto glass provides an indirect way to measure the fugacity (or differences in fugacity) of semi-volatile organic chemicals in environmental media. Here, we examined the feasibility of using thin films to measure the fugacities and fugacity capacities of organic chemicals in marine sediments. The method is based on establishing chemical equilibria between sediments and thin films coated on the interior surface of capped 2 ml glass autosampler vials. At equilibrium, the fugacity in the sediment (fs) and EVA (fe) are equal; fe is equivalent to the ratio of chemical concentration measured in EVA to (Keva-air/RT). We will show that film-air partition coefficients of a range of chlorobenzenes and PCBs correlate well with the octanol-air partition coefficients. We will further show that chlorobenzene and PCB contaminated sediments achieve chemical equilibria with the films in less than 20 minutes with insignificant losses from the sediment matrix and with coefficients of variation ranging between 15-20%. Finally we will demonstrate the application of the method for sediment fugacity and fugacity capacity measurements and discuss the relationship between measured fugacities and absorbable concentrations in benthic biota. We propose that the method provides a simple, quick and effective means to measure bioavailable chemical concentrations in sediments.
Key words: sediment, fugacity, thin-film, solid phase extraction
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