Volatile Sulfides and Their Toxicity in Freshwater Sediments

Abstract

Three forms of volatile sulfides (free hydrogen sulfide, acid-volatile sulfides [AVS] and a new form, heat-volatile sulfides [HVS]), were measured and their relationships discussed. Purging of some contaminated sediments with nitrogen at 22°C failed to remove all of the free H,S, even after 6 h. With freshly H,S-spiked uncontaminated sediment, purging of H,S was complete after 2 h; however, if the spiked sediment was allowed to stand for 53 d, H,S continued to be purged, even after 43 h. The H,S likely originates from equilibrium reactions involving reduced sulfur species in the sediment. Uncontaminated sediment spiked with H S was found to be highly toxic using a sediment-contact bioassay employing Photobacterium phosphoreum. Addition of Fe3+f which sequesters the S2-, reduced the toxicity. Two other bioassays (ATP-TOX and Toxi-Chromotest), both involving a DMSOhethanol extract of the spiked sediment, showed greatest toxicity with spiked sediment that had been standing for 22 d. The results indicate that reduced sulfur species in sediment may be a cause of toxicity observed in contaminated anoxic sediments.

Confirmation of elemental sulfur toxicity in the Microtox® assay during organic extracts assessment of freshwater sediments

“…Given that sulfur is a common sediment macrocompound in both marine and freshwater systems [15][16][17], and that the native form (elemental S) occurs in organic extracts, the interpretation of Microtox test results can be complicated. Indeed, because of its high toxicity to V. fischeri (Table 4), elevated concentrations of elemental sulfur in organic extracts of sediment may mask the effects of other toxicants, especially priority pollutants that are generally less toxic such as PAHs [31] or PCBs [32].…”

“…The confirmation that elemental sulfur, in addition to hydrogen sulfide [17], serves as an important toxicant to V. fischeri in sediment toxicity assessments may help in the interpretation of Microtox data and subsequently preclude the need for costly or unnecessary corrective measures during control programs. Consequently, any Microtox test results for crude organic extracts of sediment that do not mention elemental sulfur concentration must be regarded as questionable.…”

Intoxication aiguë accidentelle par l’hydrogène sulfuré : à propos d’un cas inhabituel

“…Les intoxications surviennent lorsque la poche d'H 2 S est rompue. C'est généralement ce qui se produit lors d'accidents dans les canalisations [15]. Dans le cas présent, cette poche aurait été percée lors de la tentative de déboucher l'évier à l'aide de la ventouse, provoquant ainsi un dégagement brutal et massif d'H 2 S. La normalité du taux atmosphérique d'H 2 S est très probablement due à l'ouverture très précoce de toutes les portes et fenêtres par les premiers témoins arrivés sur les lieux.…”

Sulfur in the marine environment

“…Therefore, AVS is considered the main factor that controls the bioavailability of heavy metals such as Cu, Zn, Cd, Ni, Hg, and Pb in sediments (Zago, Giblin 1994;Brouwer, Murphy 1995;Anderson, Wilson 2000). When a molar balance exists between the heavy metals and AVS then both chemicals are immobilized in the sediment (e.g.…”