PREDICTION OF BIOACCUMULATION OF METALS FROM CONTAMINATED SEDIMENTS BY THE OLIGOCHAETE, LUMBRICULUS-VARIEGATUS

Short-term tests with benthic species have shown that certain cationic metals (cadmium, nickel, lead. zinc, copper) in sediments are not bioavailable when acid volatile sulfide (AVS) concentrations are sufficient to bind the metals, and/or when concentrations of metals in the sediment pore water are small. It was uncertain, however, whether a similar lack of bioavailability could be predicted when evaluating metal bioaccumulation in long-term exposures. In this study, we exposed the oligochaete Lumbriculus variegatus to sediments from the lower Fox River, Wisconsin, which contained elevated concentrations of metals. Based on solid-phase metal and AVS measurements, or pore water metal concentrations, metals in the sediments were predicted to be of minimal biological availability. After a 30 day exposure to the test sediments, L. variegatus contained concentrations of metals not significantly greater than those in control oligochaetes exposed only to Lake Superior water. This indicates that metal bioavailability models based on sediment AVS content and/or pore water concentrations may be valid for long-term as well as short-term exposures of benthic species.