Biological response to variation of acid-volatile sulfides and metals in field-exposed spiked sediments

Vertical and temporal variations of acid-volatile sulfides (AVS) and simult aneously extracted metals (SEM) in sediment can control biological impacts of metals. To assess the significance of these variations in field sediment s, sediments spiked with cadmium, copper, lead, nickel, and zinc were deplo yed in Narragansett Bay for four months and recolonization by benthic organ isms investigated. In surface sediments, concentrations of AVS decreased wi th time whenever AVS exceeded SEM but remained unchanged when AVS was less than SEM; in subsurface sediments, concentrations increased slightly. Conce ntrations of total SEM decreased with time only in surface sediments in whi ch SEM exceeded AVS. Metals were not detected in interstitial waters of sed iments where AVS exceeded SEM but were significant when SEM exceeded AVS an d followed the order of solubilities of their sulfides. Concentrations in i nterstitial waters decreased with time, but exceeded U.S. Environmental Pro tection Agency chronic water quality criteria for 56 to 119 d. After 119 d, faunal assemblages in all treatments were similar to controls. Lack of bio logical response was related to vertical distributions of AVS and SEM. Biol ogical exposure took place in near-surface sediments, where AVS exceeded SE M in even the highest treatments. Therefore, concentrations of metals in in terstitial waters were low and consequently biological impacts were undetec table.