Bioavailability of desorption-resistant phenanthrene to the oligochaete Ilyodrilus templetoni.

We investigated bioavailability, as measured by the biota-sediment accumulation factor (BSAF), of reversibly sorbed and desorption-resistant phenanthrene to the deposit-feeding freshwater tubificid oligochaete Ilyodrilus templetoni. Desorption-resistant, phenanthrene-contaminated sediments were prepared by a sequential batch desorption method by washing with an isopropanol solution. The BSAFs averaged 1.20 +/- 0.32 and 0.59 +/- 0.13 for reversibly sorbed phenanthrene and desorption-resistant phenanthrene, respectively, indicating a significantly reduced bioavailability of desorption-resistant phenanthrene. A generalized model assuming a linear relationship between pore-water concentration and normalized bioaccumulation described 91% of the variance for both measured and selected literature data of the BSAF. The reduced bioavailibility of desorption-resistant phenanthrene was thus well described by physical and chemical measures of partitioning between pore water and sediment.