Journal Article DeWitt, T H ; Swartz, R C ; Hansen, D J ; ... - Environmental Toxicology and Chemistry

cadmium (IW{sub Cd}) and sediment concentrations of SEM{sub Cd} and AVS were monitored periodically and by depth during the exposure. When sediment SEM{sub Cd}/AVS ratios were {le} 1.55, mean IW{sub Cd} concentrations were less than the 96-h water-only cadmium LC50 for juvenile and subadult L. plumulosus, and mortality, growth, and reproduction were not affected. When SEM{sub Cd}/AVD ratios were {ge} 2.23, IW{sub Cd} concentrations were more than 100 times greater than the 96-h water-only cadmium LC50, and all amphipods died. These results are consistent with predictions of metal bioavailability from acute tests with metal-spiked sediments, i.e., that sediments with SEM{sub Cd}/AVS ratios < 1 are not toxic, while sediments with SEM{sub Cd}/AVS ratios > 1 may be toxic.

Numerous studies have demonstrated the efficacy of interstitial water metal concentrations and simultaneously extracted metals/acid-volatile sulfide (SEM/AVS) ratios in explaining the acute toxicity of sediment-associated metals to benthic organisms. However, no full life-cycle chronic marine or estuarine tests have been conducted for this purpose. In this study, cohorts of newborn amphipods, Leptocheirus plumulosus, were exposed to cadmium-spiked estuarine sediment for 28 d to determine effects on mortality, growth, and reproduction relative to interstitial water and SEM/AVS normalization. Seven treatments of cadmium were tested: 0 (control), 0.34, 0.74, 1.31, 1.55, 2.23, and 4.82 M SEM{sub Cd}/AVS ratios (measured concentrations). Interstitial water more »