Acid volatile sulfide

Figure 15-12 is a schematic illustration of a technique known as acid volatile sulfides/ simultaneously extracted metals analysis (AVS/SEM). Briefly, a strong acid is added to a sediment sample to release the sediment-associated sulfides, acid volatile sulfides, which are analyzed by a cold-acid purge-and-trap technique (e.g., Allen et ai, 1993). The assumption shown in Fig. 15-12 is that the sulfides are present in the sediments in the form of either FeS or MeS (a metal sulfide). In a parallel analysis, metals simultaneously released with the sulfides (the simultaneously extracted metals) are also quantified, for example, by graphite furnace atomic absorption spectrometry. Metals released during the acid attack are considered to be associated with the phases operationally defined as "exchangeable," "carbonate," "Fe and Mn oxides," "FeS," and "MeS."... 

Fig. 15-12 Schematic illustration of the acid volatile sulfides (AVS)/simultaneously extractable metal (SEM) analysis. Refer to the text for details.

Allen, H. E., Fu, G. and Deng, B. (1993). Analysis of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) for the estimation of potential toxicity in aquatic sediments. Environ. Toxicol. Chem. 12,1441-1453. 

Allen HE, Fu G, Boothman W, et al. 1994. Determination of acid volatile sulfide and selected simultaneously extractable metals in sediment. PB94-183852. 

Copper concentrations in sediment interstitial pore waters correlate positively with concentrations of dissolved copper in the overlying water column and are now used to predict the toxicity of test sediments to freshwater amphipods (Ankley et al. 1993). Sediment-bound copper is available to deposit-feeding clams, especially from relatively uncontaminated anoxic sediments of low pH (Bryan and Langston 1992). The bioavailability of copper from marine sediments, as judged by increased copper in sediment interstitial waters, is altered by increased acid volatile sulfide (AYS)... 

Ankley, G.T., V.R. Mattson, E.N. Leonard, C.W. West, and J.L. Bennett. 1993. Predicting the acute toxicity of copper in freshwater sediments evaluation of the role of acid-volatile sulfide. Environ. Toxicol. Chem. 12 315-320. 

Casas, A.M. and E.A. Crecelius. 1994. Relationship between acid volatile sulfide and toxicity of zinc, lead and copper in marine sediments. Environ. Toxicol. Chem. 13 529-536. 

Ankley GT, Phipps GL, Leonard EN, et al. 1991. Acid-volatile sulfide as a factor mediating cadmium and nickel bioavailability in contaminated sediments. Environmental Toxicology and Chemistry 10 1299-1307. 

Interpretation of these data suggests a question What is the oxidation process leading to the formation of pyrite (analytically determined as chromium-reducible sulfide, CRS) instead of simple precipitation of FeS (analytically determined as acid-volatile sulfide, AVS) AVS constituted less than 10% in the study of White et al. (35). 

Ankley, G.T., Liber, K., Call, D.J., Markee, T.P., Canfield, T.J. and Ingersoll, C.G. (1996) A field investigation of the relationship between zinc and acid volatile sulfide concentrations in freshwater sediments, Journal of Aquatic Ecosystem Health 5 (4), 255-264. 

Besser, J.M., Ingersoll, C.G. and Giesy, J.P. (1996) Effects of spatial and temporal variation of acid-volatile sulfide on the bioavailability of copper and zinc in freshwater sediments, Environmental Toxicology and Chemistry 15 (3), 286-293. 

Gonzalez, A.M. (1996) A laboratory formulated sediment incorporating synthetic acid-volatile sulfide, Environmental Toxicology and Chemistry 15 (12), 2209-2220. 

Long, E.R., MacDonald, D.D., Cubbage, J.C. and Ingersoll, C.G. (1998) Predicting the toxicity of sediment associated trace metals with simultaneously extracted trace metal acid-volatile sulfide concentrations and dry weight-normalized concentrations a critical comparison, Environmental Toxicology and Chemistry 17 (5), 972-974. 

Sibley, P.K., Ankley, G.T., Cotter, A.M. and Leonard, E.N. (1996) Predicting chronic toxicity of sediments spiked with zinc an evaluation of the acid-volatile sulfide model using a life-cycle test with the midge Chironomus teutons, Environmental Toxicology and Chemistry 15 (12), 2102—2112. 

J. M. and Boothman, W.S. (1996) Predicting the toxicity of metal-spiked laboratory sediments using acid-volatile sulfide and interstitial water normalizations, Environmental Toxicology and Chemistry 15, 2067-2079. 

Di Toro, D.M., Mahony, J.D., Hansen, D.J., Scott, K.J., Carison, A.R. and Ankley, G.T. (1992) Acid volatile sulfide predicts the acute toxicity of cadmium and nickel in sediments, Environmental Toxicology and Chemistry 26, 96-101. 

Acid volatile sulfides (AVS) Chemical analysis that quantifies the amount of sulfides present in a sample that are assumed to be capable of forming insoluble precipitates with divalent metals. See also AVS SEM ratio and SEM. Volume 2(10). 

Total sulfur (TS), acid-volatile sulfide (AVS), Cr-reducible sulfur (CRS), and extractable sulfate in sediments were determined by coulometric titrimetry,106 a method that yielded improved data quality and increased laboratory throughput. 

Iron monosulfides show an antithetic relationship with pyritic sulfur (Table I). The highest amounts of acid volatile sulfides (which remained small compared to S in pyrite) occur directly beneath the marsh sediments within the upper portions of the tidal flat deposits. The high value for iron monosulfides in the upper part of the tidal creek sediments may be related to high rates of sulfate reduction at these depths. 

An approach similar to that in soils can be applied to metal-contaminated sediments, where sulfides, measured as acid-volatile sulfides (AVS), have been demonstrated as being the predominant factor controlling metal mobility and toxicity in anaerobic sediments. The difference or ratio between SEM (simultaneous extracted metals) and AVS (SEM-AVS) is used to predict toxicity. In cases where SEM does not exceed the AVS, this approach has been shown to consistently predict the absence of toxicity (Allen et al. 1993 Ankley et al. 1996 DiToro, Hansen et al. 2001b). When SEM exceeds the AVS, toxicity is predicted, but the appearance and extent of toxicity may be determined by other binding phases (e.g., organic carbon) in the pore water. Luoma and Fisher (1997) stated that the association of metal bioavailability with AVS in sediments is not, however, straightforward in all cases and should be treated with caution. 

The most widely used approach to model metal bioavailability in sediments is based on the tendency of many toxic metals (Cd, Cu, Pb, Ni, and Zn) to form highly insoluble metal sulfides in the presence of acid-volatile sulfide. Metals are predicted... 

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