PARENT SESSION
PM11 - Sediment Toxicology
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P319) Kinetics of tributyltin (TBT) uptake and depuration in Hyalella azteca.
Bartlett, A*,1, Dixon, D1, Maguire, R2, Batchelor, S2, Borgmann, U2, 1 University of Waterloo, Waterloo, Ontario, Canada2 Environment Canada, National Water Research Institute, Burlington, Ontario, Canada
ABSTRACT- It is important to understand the behaviour of a contaminant in a test organism before designing toxicity bioassays. The purpose of this study was to address four issues of the kinetics of TBT in the freshwater amphipod, Hyalella azteca: depuration, effect of gut clearance on body concentration, time to steady state body concentration, and route of uptake from the environment. To examine depuration and gut clearance, Hyalella were exposed to TBT in water or sediment for two weeks, then transferred to clean water and allowed to depurate over a four-week period. Depuration of TBT exhibited a biphasic decline, with a stronger decrease over the first 24 h attributed primarily to gut clearance, and a half-life ranging from 6-12 d. The more gradual decrease in TBT following 24 h was most likely due to excretion from the body. As TBT in the gut contents contributed up to 30% of the total body burden, gut clearance is necessary for an accurate determination of exposure. To determine time to steady state and route of uptake, one set of Hyalella was exposed to TBT-spiked sediment, and a second set of amphipods was suspended in cages above the sediment. Hyalella accumulated TBT rapidly, reaching steady state within 14 d. Body concentrations were similar between caged and sediment-exposed animals, indicating that the primary route of uptake was via dissolved TBT. However, the rate of uptake was significantly higher in sediment-exposed amphipods, a phenomenon that could not be explained by kinetics alone. The results of this study have significant implications in the experimental design of studies involving the effects of TBT in Hyalella.
Key words: Hyalella, tributyltin, bioaccumulation, kinetics