ACID VOLATILE SULFIDE PREDICTS THE ACUTE TOXICITY OF CADMIUM AND NICKEL IN SEDIMENTS

Laboratory toxicity tests using amphipods, oligochaetes, and snails with spiked freshwater and marine sediments and with contaminated sediments collected from an EPA Superfund site demonstrate that no significant mortality occurs relative to controls if the molar concentration of acid volatile sulfide (AVS) in the sediment is greater than the molar concentration of simultaneously extracted cadmium and/or nickel. Although it is well-known that these metals can form insoluble sulfides, it apparently has not been realized that AVS is a reactive pool of solid-phase sulfide that is available to bind metals and render that portion unavailable and nontoxic to biota. Thus, the AVS concentration of a sediment establishes the boundary below which these metals cease to exhibit an acute toxicity in freshwater and marine sediments.