Citation:

Baker, J., P. Capel, AND S. Eisenreich. INFLUENCE OF COLLOIDS ON SEDIMENT-WATER PARTITION COEFFICIENTS OF POLYCHLORBIPHENYL CONGENERS IN NATURAL WATERS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-86/534 (NTIS PB90265042), 1986.

Description:

Laboratory studies have shown that speciation of hydrophobic organic pollutants in aquatic systems is too complex to model as a linear, two-phase sorption equilibrium, due to ill-defined phases and slow kinetics. his complexity is manifested in an inverse variation in sediment-water partition coefficients with the concentration of solids. easurements of the sediment-water partitioning of polychlorobiphenyl (PCB) congeners in Lake Superior provide some of the first field evidence demonstrating the importance of colloids to the fates of highly hydrophobic organic pollutants. aboratory-derived oorrelations between sedement--vater distribution coefficients and properties of both the contaminant (octanol-water partition coefficient) and the suspended solids (organic carbon content concentration) do not accurately predict PCB speciation in Lake Superior. his failure can be explained by the presence of colloidal matter with which contaminants may associate and the very low solids concentrations in oligotrophic surface waters. urprising consequence of such colloid associations is that the observed sediment-water distribution coefficients are independent of properties of highly hydrophobic compounds. hree-phase model including nonfilterable microparticles and macromolecular organic matter shows that colloidal-associated contaminants may be the dominant species in most surface waters. olloidal associations are therefore likely to significantiy impact the geochemistry of hydrophobic pollutants.

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