Sulfide, dissolved

GC/FPD has been used to measure hydrogen sulfide, free disulfide, and dissolved metal sulfide complexes in water (Radford-Knoery and Cutter 1993). Hydrogen sulfide was measured in the headspace of the sample (100 mL) with a detection limit of 0.6 pmol/L. A detection limit of 0.2 pmol/L was obtained for total dissolved sulfide. This method allows for the determination of the concentration of free sulfide that is in equilibrium with hydrogen sulfide. Complexed sulfide can be estimated from the difference between total dissolved sulfide and free sulfide. 

Broderius SJ, Smith LL Jr, Lind DT. 1977. Relative toxicity of free cyanide and dissolved sulfide forms to the fathead minnow (Pimephales promelas). Journal of the Fisheries Research Board of Canada 34 2323-2332. 

With a final example, we consider how the presence of a gas phase can serve as a chemical buffer. A fluid, for example, might maintain equilibrium with the atmosphere, soil gas in the root zone, or natural gas reservoirs in deep strata. Gases such as 02 and H2 can fix oxidation state, H2S can set the activity of dissolved sulfide, and C02 (as we demonstrate in this section) can buffer pH. 

Figure 17.1 shows the calculation results. The mass of CrVI decreases at a rate mirroring the increase in Cr111 mass, which is twice the rate at which Reaction 17.28 proceeds. Dissolved sulfide in the simulation is divided approximately evenly between HS- and H2S(aq), since pH is held to 7. The reaction consumes H2S(aq) as well as Cr()/, causing the concentration of each to decline. Since the two concentrations appear as first order terms in the rate law, reaction rate also decreases with time. 

Jameel, P. (1989), The use of ferrous chloride to control dissolved sulfides in interceptor sewers, J. Water Pollut. Contr. Fed., 61(2), 230-236. 

No experiments have been completed to determine isotopic shifts induced by Se(-II) oxidation, but results from the S isotope literature suggest they should be small. Canfield (2001) reviewed previous work on oxidation of dissolved sulfide and concluded that little isotopic fractionation occurs in this process. 

First, consider the effect of pH-increase due to the reaction of an acidic fluid with a carbonate-bearing host rocks. At pH = 5, practically all of the dissolved sulfur is undissociated H2S, whereas at pH = 9 the dissolved sulfide is almost entirely dissociated. Since H2S concentrates " S relative to dissolved sulfide ion, an increase in pH leads directly to an increase in the 5 " S of precipitated sulfides. 

Hydrogen sulfide occurs in natural gas. It also is found in many sewer gases. It is a by-product of many industrial processes. Trace amounts of dissolved H2S are found in wastewaters in equilibrium with dissolved sulfides and hydrosulfides. It also is found in volcanic eruptions, hot springs and in troposphere. The average concentration of H2S in the air is about 0.05 ppb. 

Cyanamide pigments are produced from industrial-grade calcium cyanamide which is first dissolved. Sulfide and phosphide impurities are precipitated as iron or lead salts [5.127]—[5.132] or oxidized [5.133] [5.135] and filtered off together with graphite impurities. The pure calcium cyanamide is reacted in an aqueous medium with soluble lead or zinc salts or with a slurry of lead oxide or zinc oxide [5.127], [5.129], [5.133], [5.136]—[5.138]. The pigments are filtered, washed, dried, and ground. Zinc cyanamide [5.139] and pure lead cyanamide are not explosive. An explosion reported during the production of lead cyanamide was caused by contamination with small amounts of acid or nitrates [5.140],... 

The results of the Hg2 reaction experiments using particle-size-mediated synthesized metal sulfides are shown in Table 5. The powder XRD pattern of the resulting solids reveals amorphous material formation. Previous studies using Cu,S revealed the removal of Hg by a process other than dissolved sulfide precipitation [10], Other researchers have shown that MoS2 removes Fig2 from aqueous solutions via an intercalation mechanism [11]. 

The reaction was pseudo-first-order with respect to dissolved sulfide. It was surface controlled (Figure 1), and the reaction rate showed a strong dependence on pH. Figure 2 depicts the influence of pH on the pseudo-first-order experimental rate constant kohs. The initial amount of dissolved sulfide was 10-4 M in each experiment. The rate constant increased up to... 

We were not able to measure an increase of dissolved iron at a pH higher than 5.7. Even at this pH, the recovery of dissolved iron accounted for only 28% of the dissolved sulfide consumed. This finding agrees with other studies of the reductive dissolution of ferric oxides in which dissolution rates frequently are not detectable at pH 7 (26, 27). 

Reactions 12a and 12b consume dissolved sulfide. This fact fits nicely with the data of White et al. (35), who could not detect free sulfide in their study. Dissolved sulfide is frequently absent in freshwater sediments (e.g., 39 see Urban, Chapter 10, for a discussion). This lack of sulfide is explained by an excess of reactive iron over the total sulfide concentration (19, 40). 

The occurrence of sulfide strongly affects the speciation and solubility of numerous trace elements. Solid sulfide phases may be precipitated, and dissolved sulfide and polysulfide complexes may be formed (21-23). The influence of sulfide on trace... 

In natural waters, arsenic may exist as one or more dissolved species, whose chemistry would depend on the chemistry of the waters. Over time, arsenic species dissolved in water may (1) interact with biological organisms and possibly methylate or demethylate (Chapter 4), (2) undergo abiotic or biotic oxidation, reduction, or other reactions, (3) sorb onto solids, often through ion exchange, (4) precipitate, or (5) coprecipitate. This section discusses the dissolution of solid arsenic compounds in water, the chemistry of dissolved arsenic species in aqueous solutions, and how the chemistry of the dissolved species varies with water chemistry and, in particular, pH, redox conditions, and the presence of dissolved sulfides. Discussions also include introductions to sorption, ion exchange, precipitation, and coprecipitation, which have important applications with arsenic in natural environments (Chapters 3 and 6) and water treatment technologies (Chapter 7). 

Sulfide (S ) is a bivalent monoanion produced from the decomposition of metal sulfide salts. It occurs in groundwaters, hot springs, and wastewaters. It is also formed from the bacterial reduction of sulfate. Sulfide salts in solid wastes in contact with an acid can produce hydrogen sulfide. H2S, which is highly toxic. In an aqueous sample, sulfide may be present as dissolved H2S and HS , dissolved metallic sulfide, and acid-soluble metallic sulfide contained in suspended particles. All these soluble and insoluble sulfides and dissolved H2S and HS together are termed as total sulfide. The sulfide remaining after the removal of suspended solids is termed the dissolved sulfide. Copper and silver sulfides are insoluble even under acidic conditions. Therefore, these two sulfides are not determined in the following tests. 

Methods 1 and 2 are commonly used in environmental analysis. Method 3 uses a silver electrode to indicate the end point of potentiometric titration of dissolved sulfide with standard AgN03. The electrode response is slow. 

Total sulfide in the sample - Total sulfide in the sample after removing all suspended solids) When there is no suspended solid, total sulfide is equal to dissolved sulfide. 

Suspended solids are removed from the other aliquot of the sample as follows. Add 1 mL of 6 A NaOH to a 500-mL glass bottle. Fill the bottle with the sample. Add 1 mL of A1C13 solution (10 g A1C13 6 H20 in 15 mL water). Stopper the bottle. Rotate the bottle back and forth for 2 min to flocculate the contents. Allow the contents to settle for 10 to 15 min Draw out the supernatant liquid to analyze sulfide. The difference in the sulfide values obtained from both the tests (i.e., before and after removing suspended solids from the sample), is equal to the concentration of dissolved sulfide. 

In an attempted determination of the solubility product of TI2S, the solubility of this compound in pure C02-free water was determined as 3.6 x 10-5 mol/L. What is the Ksp for TI2S Assume that the dissolved sulfide hydrolyzes practically completely to HS, and that there is no further hydrolysis to H2S. ... 

Dissolved sulfides (DS) (= S2 + HS + H2S) formed in porewaters during SR can diffuse into overlying bottom waters and contribute to 02 depletion in estuaries (Tuttle et al., 1987). Sulfides can also be removed from porewaters via reactions with Fe oxy-hydroxides to form pyrite (FeS2) (Berner, 1970, 1984). In addition to vertical molecular diffusion as a controlling factor in the DS transport, gas bubble ebullition, derived from CH4 production beneath the SR zone can be important in stripping DS from porewaters... 

Although SR has been viewed as the dominant pathway of organic matter oxidation in anaerobic salt marsh sediments (see reviews by Howarth, 1993, and Alongi, 1998), other work has suggested that microbial Fe(III) reduction (FeR) is also key in controlling the oxidation of organic C in these sediments and is inherently linked with dissolved sulfide formed from SR (Kostka and Luther, 1995). The role of Fe(III), Mn(TV), and U(VI) oxides in the nonenzymatic oxidation of organic matter has been well documented in marine and... 

The uptake of sulfides by rooted wetland plants living in anoxic sediments presents the problem of coping with toxicity since H2S is highly toxic to many organisms (Howarth and Teal, 1979). Dissolved sulfides have also been shown to inhibit coupled... 

Dissolved sulfides DS (DS = S2 + HS + H2S) formed in porewaters during SR can flux into overlying bottom waters and contribute to O2 depletion in estuaries. 

Although SR has been viewed as the dominant pathway of organic matter oxidation in anaerobic salt marsh sediments, other work has suggested that microbial Fe(III) reduction (FeR) is also key in controlling the oxidation of organic C in these sediments and is inherently linked with dissolved sulfide formed from SR. 

Carlson, P.R., and Forrest, J. (1982) Uptake of dissolved sulfide by Spartina altemiflora evidence from natural sulfur isotope abundance ratios. Science 216, 633-635. 

Raiswell, R., and Canfield, D.E. (1996) Rates of reaction between silicate iron and dissolved sulfide in Peru margin sediments. Geochim. Cosmochim. Acta 60, 2777-2787. 

Hydrogen sulfide, H2S (J]H2S = [H2S] + [HS ] + [S2 ], where [HS ] represents ca. 80% at pH 7.5-7.65 in the Black Sea anoxic interior), is the key chemical compound that defines the direction and origin of many biogeo-chemical cycles in the anoxic zone of the Black Sea. The main goal of this review is to present the contemporary inventory of hydrogen sulfide and sulfur intermediate species, the results of recent physiochemical studies of the bottom convective layer, and to discuss the sulfur isotopic composition of dissolved sulfide and sulfate. This review concludes by presenting the sulfur budget of the Black Sea. 

The total sulfide inventory of the contemporary Black Sea is about 4.6 x 103 Tg (T=1012), the main part residing between 500 and 2000 m [22]. The average dissolved sulfide concentrations at different depths are given in Table 1. The averaged data for the period before 1996 represent basin-wide averages,... 

The H2S vertical distribution is quasilinear above 500-600 m. Dissolved sulfide concentration increases gradually with depth and has an average vertical gradient of about 0.5 mmol m above 500 m, decreasing with depth (Table 1). The vertical sulfide gradient at the boundary between the entire anoxic water mass and the bottom convective layer (ca. 1700-1750 m) increases sharply and is only two times less than the vertical gradient in the upper 500 m. 

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