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MODIFICATION OF METAL PARTITIONING BY SUPPLEMENTING ACID VOLATILE SULFIDE IN FRESHWATER SEDIMENTS
Citation:
Leonard, E N., D. R. Mount, AND G T. Ankley. MODIFICATION OF METAL PARTITIONING BY SUPPLEMENTING ACID VOLATILE SULFIDE IN FRESHWATER SEDIMENTS. Presented at Midwest Regional SETAC Meeting, Racine, WI, April 26-27, 2001.
Description:
Acid volatile sulfide is a component of sediments which complexes some cationic metals and thereby influences the toxicity of these metals to benthic organisms. EPA has proposed AVS as a key normalization phase for the development of sediment quality criteria for metals. Experimental manipulation of AVS in metal-contaminated sediments may provide a means to neutralize toxicity due to metals and thereby help assess the cause of sediment toxicity. This study evaluated the effect of spiking FeS, Na2S, and Na2S/FeSO4 combined, on the concentration of AVS, simultaneously extracted metals (SEM), and pore water metals in uncontaminated and metal-enriched sediments. Experiments with solid FeS showed comparatively low effectiveness in increasing AVS. Spiking with either Na2S, or Na2S/FeSO4 combined, increased AVS and/or reduced SEM metal in Cd-, Zn- and Ni-spiked sediments, and in a Cu-contaminated sediment collected from the field. Spiking with these sediments; spiking with Na2S alone caused an apparent elevation in pore water (Cu) metal, which we believe to be an artifact of metal sulfide formation in the filtered pore water. When the Na2S/FeSO4 treatment was evaluated under conditions simulating those in sediment toxicity tests, alterations of AVS/SEM were nearly quantitative, except for Ni-spiked sediment which showed lower efficiency than the Cd, Zn, or Cu sediments. Ir appears that AVS spiking holds promise for the experimental manipulation of metal toxicity in sediments.