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Variation of acid volatile sulfide and metals in field-exposed sediments

Conference ·
OSTI ID:392369
; ;  [1]; ; ;  [2]
  1. Environmental Protection Agency, Narragansett, RI (United States)
  2. SAIC, Narragansett, RI (United States)
Use of acid volatile sulfides (AVS) to assess metals bioavailability in field sediments is complicated by vertical and temporal variation of AVS. In a field colonization experiment, Narragansett Bay sediments were spiked with cadmium, copper, lead, nickel and zinc at nominal simultaneously extracted metals(SEM):AVS ratios of 0.1, 0.8 and 3.0, and replaced in the Bay. Sediment core and IW samples were collected periodically over 4 months for AVS, SEM and dissolved metals determinations. After 4 months faunal assemblages in all treatments were similar to controls. Depth profiles of AVS and SEM were consistent with those observed in ``natural`` sediments (i.e., oxidation of AVS in surface sediments and production in deeper anoxic sediments). SEM concentrations decreased in the upper 2--3 centimeters of sediments in which SEM exceeded AVS, while no change in SEM was observed in sediments where AVS exceeded SEM. IW metals concentrations reflected relative SEM and AVS concentrations: concentrations were below detection limits in samples where SEM concentrations were less than AVS, whereas in samples where SEM exceeded AVS, significant concentrations of metals were found. Temporal variation was also evident: SEM exceeded AVS in 0.8X sediments for 1--2 months, but after four months, SEM exceeded AVS in only the top centimeter of sediment and no detectable concentrations were found in interstitial waters. Likewise, IW metals concentrations were similar in surface and deeper sediments during the first two months, but after four months were lower in surface than in deeper sediments. Overall, IW concentrations decreased with time throughout the experiment. These results suggest remobilization of metals can occur when sediments containing high concentrations of metals and AVS are relocated into oxidizing environments (e.g. dredged sediment disposal).
OSTI ID:
392369
Report Number(s):
CONF-9511137--; ISBN 1-880611-03-1
Country of Publication:
United States
Language:
English