BIOAVAILABILITY AND CHRONIC TOXICITY OF CADMIUM IN SEDIMENT TO THE ESTUARINE AMPHIPOD LEPTOCHEIRUS PLUMULOSUS

摘要

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_(Cd)/AVS ratios (measured concentrations). Interstitial water cadmium (IW_(Cd)) and sediment concentrations of SEM_(Cd) and AVS were monitored periodically and by depth during the exposure. When sediment SEM_(Cd)/AVS ratios were ≤ 1.55, mean IW_(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_(Cd)/AVS ratios were ≥ 2.23, IW_(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_(Cd)/ AVS ratios < 1 are not toxic, while sediments with SEM_(Cd)/AVS ratios > 1 may be toxic.