Relationship between acid volatile sulfide and the toxicity of zinc, lead and copper in marine sediments

Abstract

AbstractIt has been proposed that acid volatile sulfide (AVS) is an important sediment phase for determining the toxicity of certain trace metals. By evaluating the ratio of the molar quantities of simultaneously extracted metal (SEM) to AVS, the toxicity of metals to organisms in contact with sediment can be predicted. This study examines the role of AVS in predicting the toxicity of zinc, lead, and copper in marine sediments.Sediment samples were titrated with zinc, lead, and copper and subsequently analyzed for SEM, pore‐water (PW) metal, and AVS retention. In most cases, metal was not detected in the pore waters until the AVS was exceeded, suggesting that AVS is an adequate measure of the metal‐binding capacity of a sediment. The [SEM]‐to‐[AVS] ratios were calculated and toxicities predicted for each spiking concentration where [SEM]/[AVS] > 1. A 10‐d, flow‐through, acute bioassay using the marine poly‐chaete Capitella capitata was conducted to examine the prediction of toxicity from the metal titrations and the bioassay sediment chemistry data. In most cases, mortalities occurred as predicted. AVS and the [SEM]‐to‐[AVS] ratio proved useful as predictors of toxicity for zinc, lead, and perhaps copper. Another tool for predicting metal toxicity in sediments may be the [PW]/LC50 value; in every case where this ratio was >1, mortalities occurred.