THESIS APPROVAL
THESIS APPROVAL
THESIS APPROVAL
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Leppanen and Kukkonen (1998b) investigated the relative importance of<br />
ingested sediment and pore water as sources of bioaccumulation routes for pyrene in<br />
Lumbriculus variegatus. The worms were exposed to radiolabeled pyrene spiked lake<br />
sediment for 28 d and the egestion rate was followed. The results showed that pyrene<br />
accumulated mainly (61% of the body burden) through ingested material and<br />
bioavailability was decreased when exposure time increase. The data signified the<br />
importance of ingested material in bioaccumulation of hydrophobic chemicals in<br />
Lumbriculus variegatus<br />
Leppanen and Kukkonen (2000a) studied the importance of sedimentchemical<br />
contact time in bioaccumulation of pyrene and benzo(a)pyrene to<br />
Lumbriculus variegatus. The results showed that increase in sediment-chemical<br />
contact time decreased pyrene and benzo(a)pyrene uptake clearance for both feeding<br />
and nonfeeding animals. Ingest of sediment considerably increased accumulation of<br />
both compounds indicating the importance of feeding behavior in bioaccumulation of<br />
sediment-associated chemicals.<br />
Leppanen and Kukkonen (2000b) studied bioaccumulation, depuration and<br />
biotransformation of radiolabelled pyrene and benzo(a)pyrene were studied in<br />
Lumbriculus variegatus in spiked Lake Mekrijarvi (Eastern Finland) sediment. The<br />
results showed that bioaccumulation of both chemicals was fast and an apparent<br />
steady level was reached with a week. Biotransformation results showed the relative<br />
proportion of parent compound in tissues decreased continuously during the exposure.<br />
Approximately 60% of pyrene and 90% of benzo(a)pyrene was still in the parent<br />
compound.<br />
Conrad et al. (2002) studied the effect of sediment-chemical contact time on<br />
routes of uptake in Lumbriculus variegatus using sediment spiked with 14 C-labelled<br />
pyrene. The results showed that there was a decline in bioavailability with time<br />
separated in 3 stages process, including a rapid initial decline (40% decreases) during<br />
the first period, an intermediate stage with stable levels, and an ultimate decline (70%<br />
decreases) at the end of the exposure. The dietary route of uptake for pyrene varied<br />
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