The present study examined the relative importance of copper (aqueous Cu and CuO particles of different sizes) added to sediment to determine the bioaccumulation, toxicokinetics, and effects in the deposit feeder Potamopyrgus antipodarum. In experiment 1, the bioaccumulation of Cu (240μg Cu/g dry wt of sediment) added as aqueous Cu (CuCl2), nano- (6nm, 100nm), or micro- (<5μm) CuO particles in adult snails was measured. In experiment 2, a more comprehensive analysis of the toxicokinetics of Cu (aqueous Cu, 6nm, or 100nm) was conducted. In experiment 3, the effects of Cu form (aqueous Cu and 6nm CuO) on juvenile growth and survival at 0, 30, 60, 120, and 240μg Cu/g dry weight sediment were assessed. Snails took up less of the 5-μm CuO particles than nano-CuO or aqueous Cu. A substantial fraction of Cu taken up was associated with shell, and this was rapidly lost when snails were transferred to clean sediment. Net uptake rates from sediment amended with 6nm CuO and aqueous Cu were significantly higher (∼40-50%) than from sediment amended with 100nm CuO. During 2 wk of depuration, there were no significant differences in depuration rates (kd) among forms (aqueous Cu: kd=-0.12 wk-1; 6nm CuO: kd=-0.22 wk-1; 100nm CuO: kd=-0.2 wk-1). Average juvenile growth was reduced by 0.11mm (41%) at measured exposure concentrations of 127.2μg Cu/g dry weight sediment for aqueous Cu and 71.9μg Cu/g dry weight sediment for 6nm CuO compared with control; however, differences between forms were not statistically significant. Juvenile snails in the highest exposure concentrations (aqueous Cu and 6-nm CuO groups pooled) reduced their growth by 0.18mm on average (67%) compared with the control group. Although we observed minor differences in toxicity among Cu forms, effects on juvenile snail growth occurred at bulk sediment concentrations lower than those in the Canadian interim sediment quality guidelines. Characterization of the CuO particles showed that particle size distributions of commercially prepared particles deviated substantially from the manufacturers' specifications and highlighted the importance of fully characterizing particles when using them in toxicity tests.
- Copper oxide