PAH partitioning in a toxicity exposure chamber
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abstract
In surface spill, oil first forms a slick that is then broken into smaller droplets and entrained in the water column. The hypothesis that observed PAH concentrations, e.g., acenaphthene, anthracene, and pyrene, in an aqueous system are equal to the sum of the organic phase and soluble phase molar concentrations was examined. While the organic phase concentrations are proportional to the PAH mole fraction in the oil, the soluble phase molar concentrations were estimated using Raoult's law. A batch laboratory mixing vessel with a scalable mixing energy was loaded initially at various oil layer thicknesses that correspond to oil surface loadings. Total petroleum hydrocarbon concentrations increased over time according to a first order kinetic model. The first order rate constant and steady state concentration both increased with increased oil loading and with increased mean shear rates. Measured PAH concentrations correlated well with those predicted by the hypothesized model. The interdependence of mean shear rate and oil surface loading on entrainment rates was explained using the Gibbs interracial adsorption model. These results are useful for assessing the effects of oil loading conditions on crude oil PAH partitioning. This is an abstract of a paper presented at the 26th Arctic and Marine Oilspill Program Technical Seminar (Victoria, British Columbia 6/10-12/2003).
