Influence of acid volatile sulfide and metal concentrations on metal bioavailability to marine invertebrates in contaminated sediments

An 18-day microcosm study was conducted to evaluate the influence of acid v olatile sulfides (AVS) and metal additions on bioaccumulation from sediment s of Cd, Ni, and Zn in two clams (Macoma balthica and Potamocorbula amurens is) and three marine polychaetes (Neanthes arenaceodentata, Heteromastus fi liformis, and Spiophanes missionensis). Manipulation of AVS by oxidation of naturally anoxic sediments allowed use of metal concentrations typical of nature and evaluation of processes important to chronic metal exposure. A v ertical sediment column similar to that often found in nature was used to f acilitate realistic biological behavior. Results showed that AVS or porewat er (PW) metals controlled bioaccumulation in only 2 of 15 metal-animal comb inations. Bioaccumulation of all three metals by the bivalves was related s ignificantly to metal concentrations extracted from sediments (SEM) but not to [SEM - AVS] or PW metals. SEM predominantly influenced bioaccumulation of Ni and Zn in N. arenaceodentata, but Cd bioaccumulation followed PW Cd c oncentrations. SEM controlled tissue concentrations of all three metals in H. filiformis and S. missionensis, with minor influences from metal-sulfide chemistry. Significant bioaccumulation occurred when SEM was only a small fraction of AVS in several treatments. Three factors appeared to contribute to the differences between these bioaccumulation results and the results f rom toxicity tests reported previously: differences in experimental design, dietary uptake, and biological attributes of the species, including mode a nd depth of feeding.