Hydrogen sulfide concentration levels

Urinary thiosulfate levels as an exposure biomarker have been examined in rabbits (Kage et al. 1992). Urinary thiosulfate levels were detected in rabbit urine 24 hours after exposure to nonfatal concentrations of 100-200 ppm of hydrogen sulfide. Thiosulfate levels could be detected in the blood for up to 2 hours following exposure, whereas blood sulfide was not detectable. Measurements of thiosulfate levels in the blood, lung, or brain were found following fatal exposures to 500-1,000 ppm of hydrogen sulfide in experimental animals. 

Accurate measurements of hydrogen sulfide water levels are usually complicated by the presence of other sulfide compounds. A method of determining sulfide concentration in waste water by first transforming it to hydrogen sulfide and then measuring the atomic absorption of the product yielded results ranging from 3.1 to 5.1 ppm of sulfide sulfur (Parvinen and Lajunen 1994). Total sulfide levels in samples from the Mississippi River were about 0.92 ppm, while levels in pond and well water in St. Paul, Minnesota were 1.6 and 1.9 ppm, respectively (Slooff et al. 1991). 

Leahey DM, Schroeder MB. 1986. Predictions of maximum ground-level hydrogen sulfide concentrations resulting from two sour gas well blowouts. J Air Pollut Control Assoc 36 1147-1149. 

TABLE 4.6. Levels of Total Hydrogen Sulfide Concentration in Wastewater of a Sewer System and Associated Problems in Terms of Malodors, Health and Corrosion. 

The simulations depicted in Figure 8.8 also show that arather low hydrogen sulfide concentration is predicted in the gravity sewer. Only minor problems related to hydrogen sulfide production may therefore arise. Until now, the WATS model did not include sulfide release to the sewer atmosphere, sulfide oxidation or sulfide precipitation that may further reduce the concentrations shown. The predicted sulfide concentrations are, therefore, maximum levels. In case a natural capacity of iron salts in the wastewater to precipitate sulfide is inadequate, the sulfide concentrations are considered at a level that can be relatively easily controlled. 

Although there is no ASTM specification for gasoline mercaptan or hydrogen sulfide levels, a copper corrosion specification does exist. Since mercaptans and hydrogen sulfide attack copper and copper-containing alloys such as brass and bronze, it is important to minimize fuel mercaptans and hydrogen sulfide concentrations. 

Dissolved oxygen is absent at the hydrogen sulfide onset level and there is a zone of absence of detectable concentrations of both dissolved oxygen and hydrogen sulfide. 

The Navy proposes to set a SEAL 1 of 10 ppm and a SEAL 2 of 20 ppm for hydrogen sulfide. These levels are based on eye irritation reported at concentrations ranging from 5 to 30 ppm, particularly with coexposure to other chemicals or eye irritants that could lower the threshold for irritation. The Navy notes that evacuation should be considered if eye irritation becomes unbearable at hydrogen sulfide concentrations between SEAL 1 and SEAL 2, and that continued exposure could result in more permanent ocular changes, including keratoconjunctivitis and vesiculation of the corneal epithelium. 

If metals, particularly iron, are not available to precipitate the biogenic sulfide, then dissolved sulfide builds up in the pore waters and may even reach toxic levels. When iron is present the dissolved sulfide is significantly lower in concentration. The concentration profiles for dissolved sulfide in sediments often show a depletion in the upper layers and a maximum at a depth of a meter or less. The depletion is interpreted by Goldhaber and Kaplan (1974) to reflect reactions between iron oxide and dissolved sulfide to yield iron sulfides. As a consequence of different reactivities of iron oxides to aqueous sulfide, a depth may be reached where the sulfide production rate exceeds removal as iron sulfide. Volkov et al. (1972) reported that, in sediments off the Japan Depression, the free hydrogen sulfide concentration reaches as high as 150 mg h which is roughly 50% higher than that found in the Black Sea and is comparable to the maximum concentration observed at Saanich Inlet, British Columbia, by Nissenbaum et al. (1972). The... 

Hydrogen sulfide at levels well above ambient concentrations destroys immature plant tissue. This t5 e of plant injury is readily distinguished from that due to other ph5dotoxins. More-sensitive species are killed by continuous exposure to around 3000 ppb H2S, whereas other species exhibit reduced growth, leaf lesions, and defoliation. 

Use of Henry s law valid for the levels of hydrogen and hydrogen sulfide concentrations into liquid phase used in the experiments... 

EPA has established that hydrogen sulfide is a regulated toxic substance and is a hazardous substance as defined under the Federal Water Pollution Control Act. OSH A has established an acceptable ceiling concentration of 20 parts per million (ppm) for hydrogen sulfide in the workplace, with a maximum level of 50 ppm allowed for 10 minutes maximum duration if no other measurable exposure occurs. NIOSH has set a maximum Recommended Exposure Limit (REL) ceiling value (10 minutes) of 10 ppm. A complete listing of federal and state regulations and recommendations are found in Chapter 7. 

Three of five men, who lost consciousness within a few minutes of entering a partially drained underground liquid manure storage tank, died before reaching the hospital autopsy showed that two had massive liquid manure pulmonary aspiration, while the third had fulminant pulmonary edema without manure aspiration (Osbem and Crapo 1981). Markedly elevated heart-blood sulfide-ion levels indicated significant hydrogen sulfide exposure. Air samples analyzed about a week after the accident detected only 76 ppm of hydrogen sulfide, but the study authors noted that the environmental conditions were probably different (e g., warmer weather, less-concentrated manure). 

Studies performed using laboratory animals exposed to high concentrations of hydrogen sulfide gas have yielded results similar to those observed in humans exposed at high levels. Exposure of Sprague-Dawley rats to 1,655 ppm killed all 5 animals within 3 minutes (Lopez et al. 1989). All male Fischer-344 rats exposed to 500-700 ppm hydrogen sulfide gas for 4 hours died, while no rats died when exposed to concentrations up to 400 ppm under these conditions (Khan et al. 1990 Lopez et al. 1987, 1988a,... 

In a report comparing community responses to low-level exposure to a mixture of air pollutants from pulp mills, Jaakkola et al. (1990) reported significant differences in respiratory symptoms between polluted and unpolluted communities. The pollutant mixture associated with the pulp mills included particulates, sulfur dioxide, and a series of malodorous sulfur compounds. Major contributors in the latter mixture include hydrogen sulfide, methyl mercaptan, and methyl sulfides. In this study the responses of populations from three communities were compared, a nonpolluted community, a moderately polluted community, and a severely polluted community. Initial exposure estimates were derived from dispersion modeling these estimates were subsequently confirmed with measurements taken from monitoring stations located in the two polluted communities. These measurements indicated that both the mean and the maximum 4-hour concentrations of hydrogen sulfide were higher in the more severely polluted community (4 and 56 g/m3 2.9 and 40 ppb) than in the moderately polluted one (2 and 22 g/m3 1.4 and 16 ppb). Particulate measurements made concurrently, and sulfur dioxide measurements made subsequently, showed a similar difference in the concentrations of these two pollutants between the two polluted communities. 

Renal Effects. Blood urea nitrogen and serum electrolyte levels were normal in several individuals overcome by unknown concentrations of hydrogen sulfide gas in a pelt room (Audeau et al. 1985). One of these four patients had protein and blood in the urine initially, which was not detected upon later testing. Albumin and some granular casts were noted in the urine in another patient, but these findings were transient (Audeau et al. 1985). 

In Sprague-Dawley rat dams exposed to 20, 50, or 75 ppm of hydrogen sulfide for 7 hours/day from gestation day 1 through postnatal day 21, blood glucose levels were increased about 50% at all exposure concentrations (Hayden et al. 1990a). 

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