Predicting toxicity of sediments spiked with silver

Previous experiments conducted with feshwater sediments spiked with silver have shown that, when expressed on a dry weight basis, the toxicity of silver is sediment‐specific and dependent on the form of silver added (e.g., AgNO3, Ag2S). This study was conducted to assess the usefulness of silver interstitial water toxic units (IWTU) and acid volatile sulfide (AVS) concentrations in predicting the biological effects of silver species across sediments, regardless of the species of silver present. Two saltwater sediments were spiked with a series of concentrations of silver. The amphipod, Ampelisca abdita, was then exposed to the sediments in ten‐day toxicity tests. Amphipod mortality was sediment‐specific when expressed on a dry weight basis, but not when based on IWTU or simultaneously extracted metal (SEM)‐AVS. Sediments with an excess of AVS relative to SEM had IWTU 0.5, but no measurable AVS, and were generally toxic. Sediments with measurable AVS were not toxic. Reanalysis of the previously published data from the freshwater sediments spiked with silver showed mortality to be correlated with nominal SEM‐AVS and with silver IWTU. Taken together, these results support the use of AVS and silver IWTUs in predicting the toxicity of silver in sediments.