Hydrogen biogenic

Major problems in oil and gas operations result from the biogenic formation of hydrogen sulfide (H2S) in the reservoir. The presence of H2S results in increased corrosion, iron sulfide formation, higher operating costs, and reduced revenue and constitutes a serious environmental and health hazard. 

Large accumulations of shallow, biogenic methane are estimated to account for 85% of northern Ontario s forest rings (Hamilton et al. 2004). Forest rings have also been reported to form over accumulations of bitumen, coal and dissolved hydrogen sulfide (Hamilton ... 

Natural biogenic processes of bacteria, fungi, and cyanogenic plants such as sorghum, soybeans, and cassava, also release cyanide into the soil (Knowles 1988 Towill et al. 1978 WHO 1992). Cyanides (reported as cyanide, hydrogen cyanide, sodium cyanide, potassium cyanide, calcium cyanide, or copper(I) cyanide) have been detected in soil samples at 187 of the 406 hazardous waste sites, in sediment samples at 97 of the 406 hazardous waste sites, and in soil gas samples at 1 of the 406 hazardous waste sites where cyanides have been detected in some environmental medium (HazDat 1996). The HazDat information used includes data from both NPL and other Superfund sites. 

Phosphorite A hydrogenous mineral that forms in surficial sediments underlying surface waters of high biological productivity. It is composed primarily of calcium phosphate that is biogenic in origin. 

In conclusion, the combination of carbon and hydrogen isotope analysis of natural gases is a powerful tool to discriminate different origins of gases. In a plot of 8 C vs. 8D (see Fig. 3.38) not only is a distinction of biogenic and thermogeiuc gases from different enviromnents clear, but it is also possible to delineate mixtures between the different types. 

D.A. (1993) Rock magnetic criteria for the detection of biogenic magnetite. Earth Planetary Sci. Letters 120 283-300 Moukassi, M. Gougeon, M. Steinmetz, P. Dupre, B. Gleitzer, C. (1984) Hydrogen reduction of single crystals of wiistite doped with Mg, Mn, Ca, A1 and Si. Met. Trans. 15B 383-390... 

Natural emissions of sulfur compounds to the atmosphere occur from a variety of sources, including volcanic eruptions, sea spray, and a host of biogenic processes (e.g., Aneja, 1990). Most of the volcanic sulfur is emitted as S02, with smaller and highly variable amounts of hydrogen sulfide and dimethyl sulfide (CH3SCH3). Sea spray contains sulfate, some of which is carried over land masses. 

Biogenic processes, however, emit reduced forms of sulfur, including dimethyl sulfide and hydrogen sulfide, with lesser amounts of carbon disulfide (CS2), dimethyl disulfide (CH3SSCH3), carbonyl sulfide (COS), and methyl mercaptan (Cl I3SH). These reduced sulfur compounds are then oxidized in the atmosphere as described in detail in Chapter 8.E. 

All three chloroacetic acids (chloroacetic acid [MCA], dichloroacetic acid [DCA], and trichloroacetic acid [TCA]) are naturally occurring (7), with TCA being identified in the environment most frequently (reviews (278, 405 108)). However, these chlorinated acetic acids also have anthropogenic sources. The major source of natural TCA appears to be the enzymatic (chloroperoxidase) or abiotic degradation of humic and fulvic acids, which ultimately leads to chloroform and TCA. Early studies (409) and subsequent work confirm both a biogenic and an abiotic pathway. Model experiments with soil humic and fulvic acids, chloroperoxidase, chloride, and hydrogen peroxide show the formation of TCA, chloroform, and other chlorinated compounds (317, 410-412). Other studies reveal an abiotic source of TCA (412, 413). 

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