MP11 Advances in Bioaccumulation Assessment
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall
(KWO-1117-750273) Use of a parallel artificial membrane system to evaluate passive uptake and elimination in small fish.
Kwon, J.-H.1, Katz, L.1, Liljestrand, H.1, 1 The University of Texas at Austin, Austin, Texas, Unites States
ABSTRACT- A parallel artificial membrane system was developed to mimic passive mass transfer of hydrophobic organic chemicals in fish. Two aqueous phases were separated by stable lipid bilayers supported by a porous polyvinylidine difluoride (PVDF) membrane (0.1 
m pore diameter) containing dodecane. This model system comprised of outer aqueous environment, lipid membrane barrier, and cellular aqueous phase mimics the transport steps involved in partitioning of hydrophobic organic chemicals to fish. The artificial membrane system was optimized to mimic bioconcentration kinetics in small fish by controlling mass transfer resistances because the mass transfer of hydrophobic organic chemicals in fish is determined both by the lipid membrane resistance and by the aqueous resistance, depending on the pollutants′ affinity to biological membranes. The thickness of the aqueous diffusion boundary layer was adjusted by altering mixing speed. The characteristic length of the diffusion boundary layer in the artificial system was measured using a pKa-flux method for ionizable chemicals. Chlorinated aromatic hydrocarbons were chosen as model compounds for purposes of evaluation. Measured absorption rate constants, elimination rate constants and partition coefficients between the membrane and the aqueous phases are compared to those for small fish published in the literature. Characteristics of aqueous and membrane boundary layer in the artificial system are compared to those for small fish calculated by a simple diffusion model using literature data. The results suggest that the artificial system provides reasonable estimate of uptake and elimination rate constants.
Key words: bioconcentration, artificial membrane, uptake/elimination rate constant, fish