Sulfur isotopic analysis

Sulfide grains sampled from the Type II veins in the high gold zones from two drill cores were prepared for sulfur isotope analysis. Pyrite samples (n=5) have average 5 S of 8.0 + 0.5 %o and a range of 7.6 - 8.3 7oo, whereas arsenopyrite (n=4) averages 7.9 + 0.5 %o and ranges between 7.3 - 8.4 %o (Fig. 3). 

Beaudoin G, Taylor BE (1994) High precision and spatial resolution sulfur-isotope analysis using MILES laser microprobe, Geochim Cosmochim Acta 58 5055-5063 Beaudoin G, Taylor BE, Rumble D, Thiemens M (1994) Variations in the sulfur isotope composition of troUite from the Canyon Diablo iron meteorite, Geochim Cosmochim Acta 58 4253 255... 

Farquhar J, Wing BA (2003) Multiple sulfur isotope analysis applications in geochemistry and cosmochemistry. Earth Planet Sci. Lett 213 1-13 Farquhar J, Johnston DT, Wing BA, Habicht KS, Canfield DE, Airieau S, Thiemens MH (2003) Multiple sulphur isotope interpretations for biosynthetic pathways implications for biological signatures in the sulphur isotope record. Geobiology 1 27-36... 

WDNR scientists collected one sample of the SCH and a groundwater sample from a highly impacted well for sulfur isotope analysis (J. Pelczar, personal commimication, 1996). Sulfurisotope analysis was performed at the University of Waterloo Environmental Isotope Laboratory (UWEIL, 1994). Isotope data are reported as permil differences from the Canyon Diablo troihte. 

D. Rumble, T.C. Hoering, J.M. Palin (1993) Preparation of SF for sulfur isotope analysis by laser heating sulfide minerals in the presence of Fj gas. Geochim. Cosmochim. Acta 52. 4499-4512... 

N.V. Grassineau, D.P. Mattey, D. Lowry (2001) Sulfur isotope analysis of sulfide and sulfate minerals by continuous flow-isotope ratio mass spectrometry. Anal. Chem. 72, 220-225... 

Crowe, D.E., Valley, J.W. and Baker, K.L. 1990 Micro-analysis of sulfur-isotope ratios and zona-tion by laser microprobe. Geochimica et CosmochimicaActa 54 2075-2092. 

An important criticism of the use of combustion trains is that combustion is not site specific, that is all atoms in the analyte end up in the gas transferred to the IRMS. For studies of carbon isotope effects this is invariably C02. The question is especially important for carbon isotope analysis because analyte molecules of interest usually contain several different kinds of carbon atoms and therefore combustion methods average or dilute the IE s of interest. Should site specific isotope ratios be required another method of sample preparation (usually much more tedious) is necessary. Combustion methods, however, are frequently used to study nitrogen and sulfur IE s because many organic molecules are singly substituted with these atoms. Obviously, oxygen isotope effects cannot be determined using combustion trains because external oxygen is employed. Rather some type of pyrolytic sample preparation is required. 

Chemical preparation of the various sulfur compounds for isotopic analysis have been discussed by Rafter (1957), Robinson and Kusakabe (1975) among others. The gas generally used for mass-spectrometric measurement is SO2, although Puchelt et al. (1971) and Rees (1978) describe a method using SFs which has some distinct advantages it has no mass spectrometer memory effect and because fluorine is monoisotopic, no corrections of the raw data of measured isotope ratios are necessary. Comparison of 5 " S-values obtained using the conventional SO2 and the laser SFe technique has raised serious questions about the reliability of the SO2... 

Microanalytical techiuques such as laser microprobe (Kelley and Fallick 1990 Crowe et al. 1990 Hu et al. 2003 Ono et al. 2006) and ion microprobe (Chaussidon et al. 1987, 1989 Eldridge et al. 1988, 1993) have become promising tools for determining sulfur isotope ratios. These techniques have several advantages over conventional techniques such as high spatial resolution and the capability for in-situ spot analysis. Sulfur isotopes are fractionated during ion or laser bombardment, but fractionation effects are mineral specific and reproducible. 

In recent years additional informations on sulfur isotope fractionation mechanisms have been obtained from the analysis of the additional isotopes and (Farqnhar et al. 2003 Johnston et al. 2005 Ono et al. 2006, 2007). For long it was thonght and valnes carry no additional information, because sulfur isotope fractionations follow strictly mass-dependent fractionation laws. By studying all snlfnr isotopes with very high precision these authors could demonstrate that bacterial snlfate redaction follows a mass-dependent relationship that is slightly different from that expected by equilibrium fractionations. On plots vs mix-... 

Cole JE, Fairbanks RG, Shen GT (1993) The spectrum of recent variability in the southern oscillation results from a Tarawa atoll. Science 260 1790-1793 Coleman ML, Moore MP (1978) Direct reduction of sulfates to sulfur dioxide for isotope analysis. Anal Chem 50 1594-1595... 

Calhoun, J. A., T. S. Bates, and R. J. Charlson, Sulfur Isotope Measurements of Submicrometer Sulfate Aerosol Particles over the Pacific Ocean, Geophys. Res. Lett, 18, 1877-1880 (1991). Capaldo, K. P., and S. N. Pandis, Dimethylsulfide Chemistry in the Remote Marine Atmosphere Evaluation and Sensitivity Analysis of Available Mechanisms, J. Geophys. Res., 102, 23251-23267 (1997). 

S. Gas source mass spectrometry (GSMS) with electron impact (El) ion source produces nearly mono-energetic ions (similar to TIMS) and is an excellent tool for the high precision isotope analysis of light elements such as H, C, N and O, but also for S or Si.7,100,101 Precise and accurate measurements of isotope ratios have been carried out by gas source mass spectrometers with multiple ion collectors by a sample/standard comparison and the 8 values of isotope ratios were determined (see Equation 8.4). Electron impact ionization combined with mass spectrometry has been applied for elements which readily form gaseous compounds (e.g., C02 or S02) for the isotope analysis of carbon and sulfur, respectively). 

Calhoun, J. C. Zoller, W. H. Charlson, R. J. Kelly, W. R. Isotope Analysis for Understanding the Importance of DMS in the Production of Excess Sulfate over the Remote Oceans. Solid Source Mass Spectrometry The Technique and its Application. 194th National Meeting of the American Chemical Society Biogenic Sulfur in the Environment Symposium, New Orleans 1987,261-2. 

Sulfur Isotope Data Analysis of Crude Oils from the Bolivar Coastal Fields (Venezuela)... 

Sulfur Isotope Data Analysis of Crude Oils... 

Leung, Colussi and Hoffmann have used isotopic analysis in an attempt to constrain the amount of sulfate that could be produced by Crutzen s mechanism [129,130]. The first study retrieved the concentration profiles of OC S and OC S from infrared transmission spectra of the atmosphere recorded by the NASA MkIV balloon-borne interferometer. They derived an enrichment factor of 73.8 zb 8.67oo defined such that photolytically generated sulfur would be enriched in An isotopic budget based on this result shows that OCS photolysis cannot be a significant source of sulfate aerosol, since the enrichments of OCS, sulfuric acid aerosol and SO2 are known to be small [131]. A later laboratory study by the same group came to the conclusion that stratospheric photolysis results in an enrichment of 67 zb 77oo. 

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