RELATIVE IMPORTANCE OF INGESTED SEDIMENT AND PORE-WATER AS BIOACCUMULATION ROUTES FOR PYRENE TO OLIGOCHAETE (LUMBRICULUS-VARIEGATUS, MULLER)

It is generally accepted that sediment ingestion is an important route in accumulation of highly hydrophobic sediment-bound contaminants. Th e significance of this route is, however, difficult to quantify reliab ly. For this purpose, the relative importance of pare water and ingest ed sediment as sources was studied by exposing individual oligochaetes of different size to radiolabeled pyrene spiked lake sediment for 28 days. Simultaneously, their ingestion behavior (ingestion rate) was fo llowed. The design allowed comparison of the bioaccumulation process b etween individuals ingesting and noningesting sediment. Pyrene accumul ated mainly th ro ugh ingested material. After 8 days of exposure, app roximately 61% of the body burden had accumulated via ingested materia l. Uptake clearance rates differed between worm groups, which started sediment ingestion at different points of time. This was probably due to decreasing bioavailability. The data signify the importance of inge sted material in bioaccumulation of hydrophobic chemicals in deposit f eeders. The method offers a biologically sound and reliable tool for a ssessing the bioavailability of chemicals from pore water and ingested sediment for Lumbriculus variegatus.