ELIMINATION RATE CONSTANTS OF 36 PCBS IN ZEBRA MUSSELS (DREISSENA-POLYMORPHA) AND EXPOSURE DYNAMICS IN THE LAKE ST CLAIR LAKE ERIE CORRIDOR

The elimination kinetics of 36 PCB congeners, ranging in log octanol-w ater partition coefficients (log K-ow) from 5.60 to 7.50, were determi ned in zebra mussels (Dreissena polymorpha) with shell lengths from 1. 0 to 1.5 cm. Elimination rate constants, based on lipid-normalized dat a, ranged from 0.172 to 0.042 day(-1) and exhibited a significant nega tive regression with log K-ow. Time to 95% steady state ranged from 17 .5 to 71.0 days and was used to determine the period over which mussel s integrated exposure concentrations. Bioavailable PCB congener concen trations, calculated with a steady-state model, were determined from m ussels collected offshore of Middle Sister Island in western Lake Erie . Chemical concentrations in water, estimated using mussels, were with in an order of magnitude of direct Measurements for congeners with log K-ow < 6.6. The rapid elimination kinetics of zebra mussels suggests that these organisms can closely track temporal fluctuations in ambien t chemical concentrations, and therefore have the potential to regulat e contaminant cycling in aquatic ecosystems.