Evaluation of the DGT technique for predicting uptake of metal mixtures by fathead minnow (Pimephales promelas) and yellow lampmussel (Lampsilis cariosa)

Diffusive gradients in thin films (DGT) were assessed for their predictive capability of fathead minnow and yellow lampmussel bioaccumulation in copper (Cu) and lead (Pb) mixed metal exposures. Nine treatments with a matrix of 3 Cu and 3 Pb concentrations were utilized. Exposures were coupled, with organisms and DGT exposed in tanks for 6 days. The Cu measured in fish, mussel, and DGT was found not to be influenced by Pb treatment, whereas Pb accumulation was impacted by the interaction of Cu and Pb treatment. The Pb accumulation increased with increasing Cu concentration, which was attributed to the different speciation of Cu and Pb in the water where Cu binds preferentially to ligands, decreasing its bioavailability and concomitantly displacing Pb from complexing sites. The DGT values were significantly correlated with accumulated Cu and Pb in the fish, but not with Pb in the mussel. In addition, DGT was determined to better predict aquatic organism bioaccumulation of Cu than the inorganic Cu fraction calculated by the speciation model, because DGT accumulated not only inorganic metal fractions but also complexes of metal and organic matter. The present study provides insights into metal speciation in polluted environments, extends the understanding of using DGT as a tool for estimating metal bioavailability, and provides implications for the selection of geochemical modeling, biological sampling, and passive sampling techniques for monitoring trace metal contamination. Environ Toxicol Chem 2019;38:61–70. © 2018 SETAC