Accumulation Kinetics of Polycyclic Aromatic Hydrocarbons Adsorbed to Sediment by the MolluskCorbicula fluminea

The accumulation kinetics in the freshwater molluskCorbicula flumineawere measured for sediment-associated selected polycyclic aromatic hydrocarbons (PAHs), namely, anthracene (Ant), phenanthrene (Phe), pyrene (Pyr), and benzo [a] pyrene (BaP). The desorption from sediment to water was not only related to water solubility, but also depended on structural and physicochemical properties of PAHs (molecular weight, molecular area, octanol/water partition coefficientKow). Uptake of PAHs by mollusks was very fast in the first 24 h and maximum for low-molecular-weight compounds. Then animal concentrations decreased significantly after the first day for Ant and Phe, after the second day for Pyr, and after the second week for BaP (at this time the BaP concentration was higher than concentrations of the other PAHs). The kinetic data suggest that PAH uptake is related to desorption from sediment particles. Log PAH uptake is inversely related to logKow. Bioavailability of sediment-sorbed PAHs declined with contact time between sediment and animals. Assimilation from ingested material may be significant for the more strongly sorbed compound (BaP). PAHs with lowKowvalues become biologically unavailable more rapidly and more efficiently excreted.