EFFECT OF PARTICLE-XENOBIOTIC CONTACT TIME ON BIOAVAILABILITY OF SEDIMENT-ASSOCIATED BENZO(A)PYRENE TO BENTHIC AMPHIPOD, DIPOREIA SPP

A sample of Lake Michigan sediment was dosed with [C-14]benzo(a)pyrene ([C-14]BaP) and stored in the dark at 4 degrees C. Sets of experiment s exposed Diporeia spp. for 28 days to this dosed sediment after 1 wee k, 6 and 13 months storage. Just prior to the exposures, the sediment was dosed again with [H-3]benzo(a)pyrene ([H-3]BaP). The accumulation of [C-14]BaP with and without [H-3]BaP was also examined after 13 mont hs contact time to see whether the dosing with [H-3]BaP affected the b ioavailability. After 1 week contact time: the uptake clearance (K-s, g sed. g(-1) h(-1)) for [C-14]BaP was about 38% lower than the K-s for [H-3]BaP. After 6 months and 13 contact time the K,for [C-14]BaP was 46% and 42% lower, respectively, than the K-s for [H-3]BaP suggesting that contact time between the compound and sediment particles may affe ct the bioavailability of BaP. The K-s for [C-14]BaP with and without [H-3]BaP was the same. The log K-oc, of BaP varied from 5.25 to 6.18 a t different time points but then was no large difference between [H-3] BaP and [C-14]BaP. The particle size distribution of [C-14]BaP did not change during the 13 months storage and it was similar to the distrib ution of [H-3]BaP. (C) 1998 Elsevier Science B.V. All rights reserved.