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Sample records for multiple sulfur isotopes

  1. Multiple sulfur isotopes fractionations associated with abiotic sulfur transformations in Yellowstone National Park geothermal springs

    PubMed Central

    2014-01-01

    Background The paper presents a quantification of main (hydrogen sulfide and sulfate), as well as of intermediate sulfur species (zero-valent sulfur (ZVS), thiosulfate, sulfite, thiocyanate) in the Yellowstone National Park (YNP) hydrothermal springs and pools. We combined these measurements with the measurements of quadruple sulfur isotope composition of sulfate, hydrogen sulfide and zero-valent sulfur. The main goal of this research is to understand multiple sulfur isotope fractionation in the system, which is dominated by complex, mostly abiotic, sulfur cycling. Results Water samples from six springs and pools in the Yellowstone National Park were characterized by pH, chloride to sulfate ratios, sulfide and intermediate sulfur species concentrations. Concentrations of sulfate in pools indicate either oxidation of sulfide by mixing of deep parent water with shallow oxic water, or surface oxidation of sulfide with atmospheric oxygen. Thiosulfate concentrations are low (<6 μmol L-1) in the pools with low pH due to fast disproportionation of thiosulfate. In the pools with higher pH, the concentration of thiosulfate varies, depending on different geochemical pathways of thiosulfate formation. The δ34S values of sulfate in four systems were close to those calculated using a mixing line of the model based on dilution and boiling of a deep hot parent water body. In two pools δ34S values of sulfate varied significantly from the values calculated from this model. Sulfur isotope fractionation between ZVS and hydrogen sulfide was close to zero at pH < 4. At higher pH zero-valent sulfur is slightly heavier than hydrogen sulfide due to equilibration in the rhombic sulfur–polysulfide – hydrogen sulfide system. Triple sulfur isotope (32S, 33S, 34S) fractionation patterns in waters of hydrothermal pools are more consistent with redox processes involving intermediate sulfur species than with bacterial sulfate reduction. Small but resolved differences in ∆33S among

  2. Multiple sulfur isotope composition of oxidized Samoan melts and the implications of a sulfur isotope 'mantle array' in chemical geodynamics

    NASA Astrophysics Data System (ADS)

    Labidi, J.; Cartigny, P.; Jackson, M. G.

    2015-05-01

    To better address how subducted protoliths drive the Earth's mantle sulfur isotope heterogeneity, we report new data for sulfur (S) and copper (Cu) abundances, S speciation and multiple S isotopic compositions (32S, 33S, 34S, 36S) in 15 fresh submarine basaltic glasses from the Samoan archipelago, which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17 ± 11% of sulfur is oxidized (S6+) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yield homogeneous Δ33S and Δ36S values, within error of Canyon Diablo Troilite (CDT). In contrast, δ34S values are variable, ranging between +0.11 and +2.79‰ (±0.12‰ 1σ) for reduced sulfur, whereas oxidized sulfur values vary between +4.19 and +9.71‰ (±0.80‰, 1σ). Importantly, δ34S of the reduced S pool correlates with the 87Sr/86Sr ratios of the glasses, in a manner similar to that previously reported for South-Atlantic MORB, extending the trend to δ34S values up to + 2.79 ± 0.04 ‰, the highest value reported for undegassed oceanic basalts. As for EM-1 basalts from the South Atlantic ridge, the linear δ34S-87Sr/86Sr trend requires the EM-2 endmember to be relatively S-rich, and only sediments can account for these isotopic characteristics. While many authors argue that both the EM-1 and EM-2 mantle components record subduction of various protoliths (e.g. upper or lower continental crust, lithospheric mantle versus intra-metasomatized mantle, or others), it is proposed here that they primarily reflect sediment recycling. Their distinct Pb isotope variation can be accounted for by varying the proportion of S-poor recycled oceanic crust in the source of mantle plumes.

  3. Temperature effects on the fractionation of multiple sulfur isotopes by Thermodesulfobacterium and Desulfovibrio strains

    NASA Astrophysics Data System (ADS)

    Wang, P.; Sun, C.; Ono, S.; Lin, L.

    2012-12-01

    Microbial dissimilatory sulfate reduction is one of the major mechanisms driving anaerobic mineralization of organic matter in global ocean. While sulfate-reducing prokaryotes are well known to fractionate sulfur isotopes during dissimilatory sulfate reduction, unraveling the isotopic compositions of sulfur-bearing minerals preserved in sedimentary records could provide invaluable constraints on the evolution of seawater chemistry and metabolic pathways. Variations in the sulfur isotope fractionations are partly due to inherent differences among species and also affected by environmental conditions. The isotope fractionations caused by microbial sulfate reduction have been interpreted to be a sequence of enzyme-catalyzed isotope fractionation steps. Therefore, the fractionation factor depends on (1) the sulfate flux into and out of the cell, and (2) the flux of sulfur transformation between the internal pools. Whether the multiple sulfur isotope effect could be quantitatively predicted using such a metabolic flux model would provide insights into the cellular machinery catalyzing with sulfate reduction. This study examined the multiple sulfur isotope fractionation patterns associated with a thermophilic Thermodesulfobacterium-related strain and a mesophilic Desulfovibrio gigas over a wide temperature range. The Thermodesulfobacterium-related strain grew between 34 and 79°C with an optimal temperature at 72°C and the highest cell-specific sulfate reduction rate at 77°C. The 34ɛ values ranged between 8.2 and 31.6‰ with a maximum at 68°C. The D. gigas grew between 10 and 45 °C with an optimal temperature at 30°C and the highest cell-specific sulfate reduction rate at 41°C. The 34ɛ values ranged between 10.3 and 29.7‰ with higher magnitude at both lower and higher temperatures. The results of multiple sulfur isotope measurements expand the previously reported range and cannot be described by a solution field of the metabolic flux model, which calculates

  4. The multiple sulfur isotopic composition of iron meteorites: Implications for nebular evolution

    NASA Astrophysics Data System (ADS)

    Antonelli, Michael Ariel

    2013-12-01

    Multiple sulfur isotopic measurements of troilite from 61 different iron meteorites were undertaken in order to test for sulfur isotopic homogeneity within (and between) 8 different iron meteorite groups. It was found that different members within a given group of iron meteorites have homogeneous Delta 33S compositions, but that these Delta33S compositions differ between groups. This thesis shows that iron meteorites from the groups IC, IIAB, IIIAB, IIIF, and IVA have small yet resolvable enrichments or depletions in Delta33S relative to Canyon Diablo Troilite (CDT) and troilite from other non-magmatic (IAB and IIE) iron meteorites. The observed anomalous sulfur isotopic compositions in magmatic iron meteorites are most consistent with Lyman-alpha photolysis of H2S, pointing towards inheritance of an unexpected photolytically-derived sulfur component in magmatic iron meteorite groups which is absent in non-magmatic iron meteorites, chondrites, and the Earth-Moon System.

  5. Triple oxygen and multiple sulfur isotope constraints on the evolution of the post-Marinoan sulfur cycle

    NASA Astrophysics Data System (ADS)

    Crockford, Peter W.; Cowie, Benjamin R.; Johnston, David T.; Hoffman, Paul F.; Sugiyama, Ichiko; Pellerin, Andre; Bui, Thi Hao; Hayles, Justin; Halverson, Galen P.; Macdonald, Francis A.; Wing, Boswell A.

    2016-02-01

    Triple oxygen isotopes within post-Marinoan barites have played an integral role in our understanding of Cryogenian glaciations. Reports of anomalous Δ17O values within cap carbonate hosted barites however have remained restricted to South China and Mauritania. Here we extend the Δ17O anomaly to northwest Canada with our new measurements of barites from the Ravensthroat cap dolostone with a minimum Δ17O value of - 0.75 ‰. For the first time we pair triple oxygen with multiple sulfur isotopic data as a tool to identify the key processes that controlled the post-Marinoan sulfur cycle. We argue using a dynamic 1-box model that the observed isotopic trends both in northwest Canada and South China can be explained through the interplay between sulfide weathering, microbial sulfur cycling and pyrite burial. An important outcome of this study is a new constraint placed on the size of the post-Marinoan sulfate reservoir (≈0.1% modern), with a maximum concentration of less than 10% modern. Through conservative estimates of sulfate fluxes from sulfide weathering and under a small initial sulfate reservoir, we suggest that observed isotopic trends are the product of a dynamic sulfur cycle that saw both the addition and removal of the Δ17O anomaly over four to five turnovers of the post-Marinoan marine sulfate reservoir.

  6. High-Resolution Multiple Sulfur Isotope Studies of Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Mojzsis, S. J.

    2000-01-01

    Sensitive, high resolution measurements of S-32, S-31, and S-34 in individual pyrite grains in martian meteorite ALH84001 by an in situ ion microprobe multi-collection technique reveal mass-independent anomalies in Delta.S-33 (Delta.S-33 = delta.S-33 - 0.516delta.S-34) in addition to the lowest 634S found in an extraterrestrial material. Low delta.S-34 values in two pyrite grains intimately associated with carbonate in ALH84001 can be explained by the sensitivity of sulfur to fractionations in the geologic environment. Anomalies in Delta.S-33 recorded in ALH84001 pyrites probably formed by gas-phase reactions in the early martian atmosphere (>4 Ga). The discovery of clearly resolvable Delta-S33 anomalies in 2 of 12 ALH84001 pyrites analyzed in their petrographic context in thin section, is considered strong evidence for crust-atmosphere exchange and the global cycling of volatile sulfur species on early Mars. These results corroborate previous measurements by Farquhar and co-workers who used a different technique that measures that bulk Delta.S-33 values of martian meteorites. These independent techniques, and their results, suggest that sulfur affected by mass-independent fractionation is common on Mars.

  7. Multiple sulfur isotope evidence for massive oceanic sulfate depletion in the aftermath of Snowball Earth.

    PubMed

    Sansjofre, Pierre; Cartigny, Pierre; Trindade, Ricardo I F; Nogueira, Afonso C R; Agrinier, Pierre; Ader, Magali

    2016-07-22

    The terminal Neoproterozoic Era (850-542 Ma) is characterized by the most pronounced positive sulfur isotope ((34)S/(32)S) excursions in Earth's history, with strong variability and maximum values averaging δ(34)S∼+38‰. These excursions have been mostly interpreted in the framework of steady-state models, in which ocean sulfate concentrations do not fluctuate (that is, sulfate input equals sulfate output). Such models imply a large pyrite burial increase together with a dramatic fluctuation in the isotope composition of marine sulfate inputs, and/or a change in microbial sulfur metabolisms. Here, using multiple sulfur isotopes ((33)S/(32)S, (34)S/(32)S and (36)S/(32)S ratios) of carbonate-associated sulfate, we demonstrate that the steady-state assumption does not hold in the aftermath of the Marinoan Snowball Earth glaciation. The data attest instead to the most impressive event of oceanic sulfate drawdown in Earth's history, driven by an increased pyrite burial, which may have contributed to the Neoproterozoic oxygenation of the oceans and atmosphere.

  8. Multiple sulfur isotope evidence for massive oceanic sulfate depletion in the aftermath of Snowball Earth

    NASA Astrophysics Data System (ADS)

    Sansjofre, Pierre; Cartigny, Pierre; Trindade, Ricardo I. F.; Nogueira, Afonso C. R.; Agrinier, Pierre; Ader, Magali

    2016-07-01

    The terminal Neoproterozoic Era (850-542 Ma) is characterized by the most pronounced positive sulfur isotope (34S/32S) excursions in Earth's history, with strong variability and maximum values averaging δ34S~+38‰. These excursions have been mostly interpreted in the framework of steady-state models, in which ocean sulfate concentrations do not fluctuate (that is, sulfate input equals sulfate output). Such models imply a large pyrite burial increase together with a dramatic fluctuation in the isotope composition of marine sulfate inputs, and/or a change in microbial sulfur metabolisms. Here, using multiple sulfur isotopes (33S/32S, 34S/32S and 36S/32S ratios) of carbonate-associated sulfate, we demonstrate that the steady-state assumption does not hold in the aftermath of the Marinoan Snowball Earth glaciation. The data attest instead to the most impressive event of oceanic sulfate drawdown in Earth's history, driven by an increased pyrite burial, which may have contributed to the Neoproterozoic oxygenation of the oceans and atmosphere.

  9. Multiple sulfur isotope evidence for massive oceanic sulfate depletion in the aftermath of Snowball Earth

    PubMed Central

    Sansjofre, Pierre; Cartigny, Pierre; Trindade, Ricardo I. F.; Nogueira, Afonso C. R.; Agrinier, Pierre; Ader, Magali

    2016-01-01

    The terminal Neoproterozoic Era (850–542 Ma) is characterized by the most pronounced positive sulfur isotope (34S/32S) excursions in Earth's history, with strong variability and maximum values averaging δ34S∼+38‰. These excursions have been mostly interpreted in the framework of steady-state models, in which ocean sulfate concentrations do not fluctuate (that is, sulfate input equals sulfate output). Such models imply a large pyrite burial increase together with a dramatic fluctuation in the isotope composition of marine sulfate inputs, and/or a change in microbial sulfur metabolisms. Here, using multiple sulfur isotopes (33S/32S, 34S/32S and 36S/32S ratios) of carbonate-associated sulfate, we demonstrate that the steady-state assumption does not hold in the aftermath of the Marinoan Snowball Earth glaciation. The data attest instead to the most impressive event of oceanic sulfate drawdown in Earth's history, driven by an increased pyrite burial, which may have contributed to the Neoproterozoic oxygenation of the oceans and atmosphere. PMID:27447895

  10. Multiple sulfur isotope evidence for massive oceanic sulfate depletion in the aftermath of Snowball Earth.

    PubMed

    Sansjofre, Pierre; Cartigny, Pierre; Trindade, Ricardo I F; Nogueira, Afonso C R; Agrinier, Pierre; Ader, Magali

    2016-01-01

    The terminal Neoproterozoic Era (850-542 Ma) is characterized by the most pronounced positive sulfur isotope ((34)S/(32)S) excursions in Earth's history, with strong variability and maximum values averaging δ(34)S∼+38‰. These excursions have been mostly interpreted in the framework of steady-state models, in which ocean sulfate concentrations do not fluctuate (that is, sulfate input equals sulfate output). Such models imply a large pyrite burial increase together with a dramatic fluctuation in the isotope composition of marine sulfate inputs, and/or a change in microbial sulfur metabolisms. Here, using multiple sulfur isotopes ((33)S/(32)S, (34)S/(32)S and (36)S/(32)S ratios) of carbonate-associated sulfate, we demonstrate that the steady-state assumption does not hold in the aftermath of the Marinoan Snowball Earth glaciation. The data attest instead to the most impressive event of oceanic sulfate drawdown in Earth's history, driven by an increased pyrite burial, which may have contributed to the Neoproterozoic oxygenation of the oceans and atmosphere. PMID:27447895

  11. Matrix effects of calcium on high-precision sulfur isotope measurement by multiple-collector inductively coupled plasma mass spectrometry.

    PubMed

    Liu, Chenhui; Bian, Xiao-Peng; Yang, Tao; Lin, An-Jun; Jiang, Shao-Yong

    2016-05-01

    Multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has been successfully applied in the rapid and high-precision measurement for sulfur isotope ratios in recent years. During the measurement, the presence of matrix elements would affect the instrumental mass bias for sulfur and these matrix-induced effects have aroused a lot of researchers' interest. However, these studies have placed more weight on highlighting the necessity for their proposed correction protocols (e.g., chemical purification and matrix-matching) while less attention on the key property of the matrix element gives rise to the matrix effects. In this study, four groups of sulfate solutions, which have different concentrations of sulfur (0.05-0.60mM) but a constant sequence of atomic calcium/sulfur ratios (0.1-50), are investigated under wet (solution) and dry (desolvation) plasma conditions to make a detailed evaluation on the matrix effects from calcium on sulfur isotope measurement. Based on a series of comparative analyses, we indicated that, the matrix effects of calcium on both measured sulfur isotope ratios and detected (32)S signal intensities are dependent mainly on the absolute calcium concentration rather than its relative concentration ratio to sulfur (i.e., atomic calcium/sulfur ratio). Also, for the same group of samples, the matrix effects of calcium under dry plasma condition are much more significant than that of wet plasma. This research affords the opportunity to realize direct and relatively precise sulfur isotope measurement for evaporite gypsum, and further provides some suggestions with regard to sulfur isotope analytical protocols for sedimentary pore water.

  12. Sulfur isotopic data

    SciTech Connect

    Rye, R.O.

    1987-01-01

    Preliminary sulfur isotope data have been determined for samples of the Vermillion Creek coal bed and associated rocks in the Vermillion Creek basin and for samples of evaporites collected from Jurassic and Triassic formations that crop out in the nearby Uinta Mountains. The data are inconclusive, but it is likely that the sulfur in the coal was derived from the evaporites.

  13. Separation of sulfur isotopes

    DOEpatents

    DeWitt, Robert; Jepson, Bernhart E.; Schwind, Roger A.

    1976-06-22

    Sulfur isotopes are continuously separated and enriched using a closed loop reflux system wherein sulfur dioxide (SO.sub.2) is reacted with sodium hydroxide (NaOH) or the like to form sodium hydrogen sulfite (NaHSO.sub.3). Heavier sulfur isotopes are preferentially attracted to the NaHSO.sub.3, and subsequently reacted with sulfuric acid (H.sub.2 SO.sub.4) forming sodium hydrogen sulfate (NaHSO.sub.4) and SO.sub.2 gas which contains increased concentrations of the heavier sulfur isotopes. This heavy isotope enriched SO.sub.2 gas is subsequently separated and the NaHSO.sub.4 is reacted with NaOH to form sodium sulfate (Na.sub.2 SO.sub.4) which is subsequently decomposed in an electrodialysis unit to form the NaOH and H.sub.2 SO.sub.4 components which are used in the aforesaid reactions thereby effecting sulfur isotope separation and enrichment without objectionable loss of feed materials.

  14. Meteoritic Sulfur Isotopic Analysis

    NASA Technical Reports Server (NTRS)

    Thiemens, Mark H.

    1996-01-01

    Funds were requested to continue our program in meteoritic sulfur isotopic analysis. We have recently detected a potential nucleosynthetic sulfur isotopic anomaly. We will search for potential carriers. The documentation of bulk systematics and the possible relation to nebular chemistry and oxygen isotopes will be explored. Analytical techniques for delta(sup 33), delta(sup 34)S, delta(sup 36)S isotopic analysis were improved. Analysis of sub milligram samples is now possible. A possible relation between sulfur isotopes and oxygen was detected, with similar group systematics noted, particularly in the case of aubrites, ureilites and entstatite chondrites. A possible nucleosynthetic excess S-33 has been noted in bulk ureilites and an oldhamite separate from Norton County. High energy proton (approximately 1 GeV) bombardments of iron foils were done to experimentally determine S-33, S-36 spallogenic yields for quantitation of isotopic measurements in iron meteorites. Techniques for measurement of mineral separates were perfected and an analysis program initiated. The systematic behavior of bulk sulfur isotopes will continue to be explored.

  15. Multiple Sulfur Isotopic Composition of Sulfate in the Fresh Water, Deception Island, South Shetland Islands, Antarctica

    NASA Astrophysics Data System (ADS)

    Lee, I.; Lee, J.; Seo, J.; Park, B.; Farquhar, J.; Kaufman, A. J.; Kim, K.

    2008-12-01

    Isotopic compositions of sulfur (δ33S, δ34S, δ36S) from sulfate of the fresh water in Deception island were measured to provide the information on the sources of sulfate in the surface water and to check the possibility of mass independent fractionation of sulfur in this area. Most part of the Deception Island is covered by volcanic rocks from the recent activities not exceeding 200 ka. To south and north of the Deception Island, plutonic rocks of granitic composition ranging from Mesozoic to Cenozoic are widely distributed. Because of the recent volcanic activities in Deception Island (most recent eruptions in 1970), sulfur containing aerosols produced in the stratosphere might have been added and could contribute the mass independent signature to the hydrologic system. The δ34S values of sulfate extracted from water samples at Deception Island range from 8.1 to 17.3 per mil. The Δ33S values of sulfate extracted from water samples at Deception island range from 0.000 to 0.046 per mil. Δ36S values of sulfate extracted from water samples range from -0.257 to 0.186 per mil. These waters represent the concentration from Antarctic snow and ice. In Antarctic region the natural source of sulfate dissolved in water could be originated from marine biogenic source (DMS), sea-salt, volcanic source, or other continental sources. The δ34S values of water sulfate at Deception Island well support the dominance of marine biogenic origin for the source of sulfur. Mass independent sulfur isotope anomalies are known to be produced through photochemical reactions and have been reported in Precambrian rock samples, recent atmospheric aerosols, and ice cores containing the volcanic erupted ashes piercing through stratosphere. Isotopic composition of sulfate in fresh water indicates that only mass-dependent fractionation was prevailing for sulfur isotopic system at Deception Island.

  16. Development of a Tunable Laser Spectroscopic Method for Determining Multiple Sulfur Isotope Composition of Nanomoles of SO2

    NASA Astrophysics Data System (ADS)

    Guo, W.; Christensen, L. E.

    2013-12-01

    Multiple sulfur isotope (32S, 33S, 34S, 36S) analyses of geological material provide important constraints on the sulfur cycles on Earth [1] and other planetary bodies, e.g., Mars [2]. However, most current multiple sulfur isotope measurements are performed on magnetic sector isotope ratio mass spectrometers (IRMS) and thus require relatively large sample size (usually about several micromoles of sulfur, except the MC-ICPMS and SIMS methods) and time-consuming sample preparation procedures. More importantly, these IRMS methods demand relatively sophisticated instrumentation, and are not ideal for field measurements or flight missions. In contrast, laser spectroscopic methods provide opportunities for significantly reducing the sample size requirement and enabling real-time monitoring in the field, and have been proven to be of great importance in the isotopic measurements of many molecules in nature, e.g. CO2, H2O, N2O, CH4. Based on a prototype built for measuring δ34S of SO2 [3], we're developing a new tunable laser spectrometer (TLS) for simultaneously determining the δ34S and Δ33S of nanomoles of pure SO2. We have identified a new spectral window (<1 cm-1 wide) suitable for measuring 32SO2, 33SO2, 34SO2 simultaneously. Ongoing work focuses on increasing the optical path length of the analysis cell and determining the optimal analytical conditions, with the goal of achieving ≤0.5‰ precision in both δ34S and Δ33S over 30 seconds of analysis duration of ~20 nmol of pure SO2. Progress of these developments and comparison with conventional IRMS methods will be presented at the meeting. As a case study, we will also present preliminary TLS results from laboratory low pressure SO2 UV photolysis experiments where δ34S and Δ33S of the residual SO2 are expected to decrease as the photolysis proceeds [4]. Future developments of this method will involve the coupling of a sample introduction system to enable multiple sulfur isotope analysis of samples other than

  17. Atmospheric record in the Hadean Eon from multiple sulfur isotope measurements in Nuvvuagittuq Greenstone Belt (Nunavik, Quebec).

    PubMed

    Thomassot, Emilie; O'Neil, Jonathan; Francis, Don; Cartigny, Pierre; Wing, Boswell A

    2015-01-20

    Mass-independent fractionation of sulfur isotopes (S-MIF) results from photochemical reactions involving short-wavelength UV light. The presence of these anomalies in Archean sediments [(4-2.5 billion years ago, (Ga)] implies that the early atmosphere was free of the appropriate UV absorbers, of which ozone is the most important in the modern atmosphere. Consequently, S-MIF is considered some of the strongest evidence for the lack of free atmospheric oxygen before 2.4 Ga. Although temporal variations in the S-MIF record are thought to depend on changes in the abundances of gas and aerosol species, our limited understanding of photochemical mechanisms complicates interpretation of the S-MIF record in terms of atmospheric composition. Multiple sulfur isotope compositions (δ(33)S, δ(34)S, and δ(36)S) of the >3.8 billion-year-old Nuvvuagittuq Greenstone Belt (Ungava peninsula) have been investigated to track the early origins of S-MIF. Anomalous S-isotope compositions (Δ(33)S up to +2.2‰) confirm a sedimentary origin of sulfide-bearing banded iron and silica-rich formations. Sharp isotopic transitions across sedimentary/igneous lithological boundaries indicate that primary surficial S-isotope compositions have been preserved despite a complicated metamorphic history. Furthermore, Nuvvuagittuq metasediments recorded coupled variations in (33)S/(32)S, (34)S/(32)S, and (36)S/(32)S that are statistically indistinguishable from those identified several times later in the Archean. The recurrence of the same S-isotope pattern at both ends of the Archean Eon is unexpected, given the complex atmospheric, geological, and biological pathways involved in producing and preserving this fractionation. It implies that, within 0.8 billion years of Earth's formation, a common mechanism for S-MIF production was established in the atmosphere. PMID:25561552

  18. Atmospheric record in the Hadean Eon from multiple sulfur isotope measurements in Nuvvuagittuq Greenstone Belt (Nunavik, Quebec)

    PubMed Central

    Thomassot, Emilie; O’Neil, Jonathan; Francis, Don; Cartigny, Pierre; Wing, Boswell A.

    2015-01-01

    Mass-independent fractionation of sulfur isotopes (S-MIF) results from photochemical reactions involving short-wavelength UV light. The presence of these anomalies in Archean sediments [(4–2.5 billion years ago, (Ga)] implies that the early atmosphere was free of the appropriate UV absorbers, of which ozone is the most important in the modern atmosphere. Consequently, S-MIF is considered some of the strongest evidence for the lack of free atmospheric oxygen before 2.4 Ga. Although temporal variations in the S-MIF record are thought to depend on changes in the abundances of gas and aerosol species, our limited understanding of photochemical mechanisms complicates interpretation of the S-MIF record in terms of atmospheric composition. Multiple sulfur isotope compositions (δ33S, δ34S, and δ36S) of the >3.8 billion-year-old Nuvvuagittuq Greenstone Belt (Ungava peninsula) have been investigated to track the early origins of S-MIF. Anomalous S-isotope compositions (Δ33S up to +2.2‰) confirm a sedimentary origin of sulfide-bearing banded iron and silica-rich formations. Sharp isotopic transitions across sedimentary/igneous lithological boundaries indicate that primary surficial S-isotope compositions have been preserved despite a complicated metamorphic history. Furthermore, Nuvvuagittuq metasediments recorded coupled variations in 33S/32S, 34S/32S, and 36S/32S that are statistically indistinguishable from those identified several times later in the Archean. The recurrence of the same S-isotope pattern at both ends of the Archean Eon is unexpected, given the complex atmospheric, geological, and biological pathways involved in producing and preserving this fractionation. It implies that, within 0.8 billion years of Earth’s formation, a common mechanism for S-MIF production was established in the atmosphere. PMID:25561552

  19. Multiple sulfur and carbon isotope composition of sediments from the Belingwe Greenstone Belt (Zimbabwe): A biogenic methane regulation on mass independent fractionation of sulfur during the Neoarchean?

    NASA Astrophysics Data System (ADS)

    Thomazo, Christophe; Nisbet, Euan G.; Grassineau, Nathalie V.; Peters, Marc; Strauss, Harald

    2013-11-01

    To explore the linkage between mass-independent sulfur isotope fractionation (MIF-S) and δ13Corg excursions during the Neoarchean, as well as the contemporary redox state and biogeochemical cycling of carbon and sulfur, we report the results of a detailed carbon and multiple sulfur (δ34S, δ33S, δ36S) isotopic study of the ∼2.7 Ga Manjeri and ∼2.65 Ga Cheshire formations of the Ngezi Group (Belingwe Greenstone Belt, Zimbabwe). Multiple sulfur isotope data show non-zero Δ33S and Δ36S values for sediments older than 2.4 Ga (i.e. prior to the Great Oxidation Event, GOE), indicating MIF-S thought to be associated with low atmospheric oxygen concentration. However, in several 2.7-2.5 Ga Neoarchean localities, small-scale variations in MIF-S signal (magnitude) seem to correlate with negative excursion in δ13Corg, possibly reflecting a global connection between the relative reaction rate of different MIF-S source reaction and sulfur exit channels and the biogenic flux of methane into the atmosphere during periods of localized, microbiologically mediated, shallow surface-water oxygenation. The Manjeri Formation black shales studied here display a wide range of δ13Corg between -35.4‰ and -16.2‰ (average of -30.3 ± 6.0‰, 1σ), while the Cheshire Formation shales have δ13Corg between -47.7‰ and -35.1‰ (average -41.3 ± 3‰, 1σ). The δ34S values of sedimentary sulfides from Manjeri Formation vary between -15.15‰ and +2.37‰ (average -1.71 ± 4.76‰, 1σ), showing very small and mostly negative Δ33S values varying from -0.58‰ to 0.87‰ (average 0.02 ± 0.43‰, 1σ). Cheshire Formation black shale sulfide samples measured in this study have δ34S values ranging from -2.11‰ to 2.39‰ (average 0.25 ± 1.08‰, 1σ) and near zero and solely positive Δ33S anomalies between 0.14‰ and 1.17‰ (average 0.56 ± 0.29‰, 1σ). Moreover, Δ36S/Δ33S in the two formations are comparable with a slope of -1.38 (Manjeri Formation) and -1.67 (Cheshire

  20. Multiple oxygen and sulfur isotope compositions of atmospheric sulfate in Baton Rouge, LA, USA

    NASA Astrophysics Data System (ADS)

    Jenkins, Kathryn A.; Bao, Huiming

    Secondary atmospheric sulfates (SAS) is the ultimate oxidation product and sink for sulfur gases of biological, volcanic, and anthropogenic origins on Earth. Their presence in the atmosphere as aqueous or solid phases contributes to acid rain and climate change, thus, understanding SAS formation pathways is pertinent. There has been extensive measurement of δ34S values for SAS, which mainly aimed at source identification. Relatively fewer oxygen isotope compositions ( δ18O, Δ 17O), which are most useful for resolving competing oxidation pathways, were available, however. This study represents the first effort to characterize the Δ 17O, δ18O, and δ34S simultaneously for SAS in a tropospheric air shed. We measured a total of 20 samples collected in Baton Rouge (LA, USA) during a 600-day period. The isotope compositions for atmospheric sulfate range from +0.25‰ to +1.43‰ for Δ 17O, +11.8‰ to +19.3‰ for δ18O, and -1.4‰ to +3.8‰ for δ34S. No apparent correlation is found among Δ 17O, δ18O, or δ34S values. The Δ 17O has no seasonal variation and its values are consistent with an oxidation pathway dominated by aqueous H 2O 2. The δ18O and δ34S are within the range of those observed in other sites around the world and are not characteristic for Baton Rouge. Despite the huge variability in atmospheric condition among mid-latitude sites, the long-term average Δ 17O value for SAS appears to fall within a fairly narrow range from +0.6‰ to +0.8‰, which is ˜1‰ to 2‰ lower than those in polar sites.

  1. Pyrite multiple-sulfur isotope evidence for rapid expansion and contraction of the early Paleoproterozoic seawater sulfate reservoir

    NASA Astrophysics Data System (ADS)

    Scott, Clint; Wing, Boswell A.; Bekker, Andrey; Planavsky, Noah J.; Medvedev, Pavel; Bates, Steven M.; Yun, Misuk; Lyons, Timothy W.

    2014-03-01

    Earth's oxygenation is often described in terms of two unidirectional steps at the beginning and end of the Proterozoic Eon, separated by a long-lived intermediate redox state. Recent work defines a more complicated path to oxygenation, exemplified by an apparent drop in oxidation state following the early Paleoproterozoic Lomagundi carbon isotope excursion. The timing of this proposed drop in oxidation state is not well constrained, and it is not clear how it relates to redox conditions during the remainder of the Proterozoic. Here we present a study of pyrite multiple-sulfur isotopes, supported by Fe speciation and organic carbon isotopes, from early Paleoproterozoic black shales. We find evidence for the rapid expansion of the seawater sulfate reservoir during the Great Oxidation Event at ca. 2.3 Ga followed by a subsequent contraction in the size of the seawater sulfate reservoir at ca. 2.05 Ga. This scenario is consistent with the emerging view of a rise and fall in surface oxidation state during the early Paleoproterozoic. Comparison of our new data to other records of the seawater sulfate reservoir suggests that the elevated sulfate concentrations that characterize the early Paleoproterozoic did not return until the late Neoproterozoic.

  2. Multiple oxygen and sulfur isotope compositions of secondary atmospheric sulfate in a mega-city in central China

    NASA Astrophysics Data System (ADS)

    Li, Xiaoqian; Bao, Huiming; Gan, Yiqun; Zhou, Aiguo; Liu, Yunde

    2013-12-01

    Sulfate aerosol is an important atmosphere constituent that can be formed secondarily through the oxidation of sulfur gases. Atmospheric sulfur oxidation can take different pathways depending on meteorological conditions, which affects sulfate aerosol size and composition and therefore local or global climate. The magnitude of 17O enrichment (Δ17O) in secondary atmospheric sulfate (SAS) is a tracer for the apportionment of different sulfur oxidation pathways. Atmospheric chemistry-transport models predict a low 17O enrichment (Δ17O < 1‰) for SAS in mid-latitude continental sites. However, there are few long-term site observations to test the prediction, and data from interior metropolitan sites are entirely absent. We report here multiple oxygen and sulfur isotope compositions (Δ17O, δ18O, and δ34S) of SAS collected over a 950-day period in the city of Wuhan, central China, and to compare to data from a similar sampling campaign in the city of Baton Rouge, LA, U.S.A. The isotope compositions of bulk atmospheric sulfate closely reflect those of SAS in Wuhan, with the Δ17O ranging from 0.14‰ to 1.02‰, the δ18O from 8.0‰ to 16.1‰, and the δ34S from 2.1‰ to 7.3‰. The average Δ17O value at 0.53‰-0.59‰ is consistent with model prediction for continental interior, mid-latitude sites. The Asian monsoon-influenced meteorological condition in Wuhan appears to produce a weak but discernible seasonal pattern for Δ17O and δ18O of the SAS. The average rainwater pH value is higher in Wuhan than in Baton Rouge (5.47 versus 4.78) while the two cities have a statistically identical average SAS Δ17O value. We suggest that the higher pH does result in a higher fraction of SAS generated by aqueous O3 oxidation, but the resulted higher Δ17O value for SAS is diluted by the 17O-normal SAS generated from an enhanced transition-metal-catalyzed O2 oxidation pathway. The enhancement is corroborated with the much higher content of atmospheric particulate matter

  3. Microbial sulfate reduction, multiple sulfur isotopes, and the ca. 3.46 Ga Dresser Formation (Western Australia)

    NASA Astrophysics Data System (ADS)

    Mojzsis, S. J.

    2006-12-01

    Cherty barite-containing rocks from the ca. 3.46 Ga Dresser Formation (Warrawoona Group, Pilbara Craton, Australia) show low degrees of metamorphism and slight deformation, which argues against extensive post- diagenetic alteration of the sulfur isotopes. Groves et al. (1981) interpreted the depositional setting as precipitated gypsum replaced by barite in brine ponds separated from the sea by a sand berm. Buick and Dunlop (1990) postulated the origin of the sulfate from originally low sulfate sea water in evaporative briny lagoons locally supplemented by the phototrophic oxidation of volcanogenic sulfide. Van Kranendonk (2006) presented new high-resolution mapping and geochemical analyses that showed the extensive bedded chert + barite units formed during discrete episodes of volcanogenic hydrothermal circulation during exhalative cooling of a felsic magma chamber. In conditions analogous to contemporary S-rich volcanism, a silicic magma chamber with associated caldera collapse and seawater incursions will evolve highly oxidized volatile-laden saline fluids (Scaillet et al., 1998). This leads to the expulsion of oxidized fluids which in the hydrolysis reaction: 4H20 + 4SO2 ↔ H2S + 3H+ + 3HSO4- can stabilize sulfate without the intervention of oxygenic photosynthesizers. Locally recharged submarine brine-pools with reactive SO42- and Ba2+ leached from basalt forms barite. Multiple S-isotopes (^{33}S/^{32}S vs. S^{34}S/^{32}S) of sulfate-sulfide pairs provide a crucial clue to the origin of the sulfur in the Dresser rocks. Barites in sample GSWA 169711 (A-I from Farquhar et al., 2000) have average Δ^{33}S values = -0.98±0.022‰ and average δ34SVCDT = +4.9‰ that form a linear array (r2=0.977) of mass-dependent slope λ = 0.512. Brine pool sulfate rapidly scavenged by Ba2+ makes barite; the solubility of barite is low (ΔH°r = 6.35 kcal mol-1, log K = -9.97), and Ba2+ leached from basalt (average Archean basalt contains 569 ppm Ba; Condie, 1993) was plentiful

  4. Comparing orthomagmatic and hydrothermal mineralization models for komatiite-hosted nickel deposits in Zimbabwe using multiple-sulfur, iron, and nickel isotope data

    NASA Astrophysics Data System (ADS)

    Hofmann, Axel; Bekker, Andrey; Dirks, Paul; Gueguen, Bleuenn; Rumble, Doug; Rouxel, Olivier J.

    2014-01-01

    Trojan and Shangani mines are low-grade (<0.8 % Ni), komatiite-hosted nickel sulfide deposits associated with ca. 2.7 Ga volcano-sedimentary sequences of the Zimbabwe craton. At both mines, nickel sulfide mineralization is present in strongly deformed serpentinite bodies that are enveloped by a complex network of highly sheared, silicified, and sulfide-bearing metasedimentary rocks. Strong, polyphase structural-metamorphic-metasomatic overprints in both the Trojan and Shangani deposits make it difficult to ascertain if sulfide mineralization was derived from orthomagmatic or hydrothermal processes, or by a combination of both. Multiple S, Fe, and Ni isotope analyses were applied to test these competing models. Massive ores at Shangani Mine show mass-dependent fractionation of sulfur isotopes consistent with a mantle sulfur source, whereas S-isotope systematics of net-textured ore and disseminated ore in talcose serpentinite indicates mixing of magmatic and sedimentary sulfur sources, potentially via post-magmatic hydrothermal processes. A restricted range of strongly mass-independent Δ33S values in ore samples from Trojan Mine likely reflects high-temperature assimilation of sulfur from supracrustal rocks and later superimposed low-temperature hydrothermal remobilization. Iron isotope values for most Ni-bearing sulfides show a narrow range suggesting that, in contrast to sulfur, nearly all of iron was derived from an igneous source. Negative Ni isotope values also agree with derivation of Ni from ultramafic melt and a significant high-temperature fractionation of Ni isotopes. Fe isotope values of some samples from Shangani Mine are more fractionated than expected to occur in high-temperature magmatic systems, further suggesting that hydrothermal processes were involved in either low-grade ore formation (liberation of Ni from olivine by sulfur-bearing hydrothermal fluids) or remobilization of existing sulfides potentially inducing secondary Ni

  5. Multiple oxygen and sulfur isotope compositions of secondary atmospheric sulfate in the city of Wuhan, central China

    NASA Astrophysics Data System (ADS)

    Li, X.; Bao, H.; Zhou, A.; Wang, D.

    2012-12-01

    Secondary atmospheric sulfate (SAS) is the oxidation product and sink for sulfur gases of biological, volcanic, and anthropogenic origins on Earth. SAS can be produced from gas-phase OH-radical oxidation and five aqueous-phase chemical reactions including aqueous-phase S (IV) oxidation reactions by H2O2, O3, oxygen catalyzed by Fe3+ and Mn2+, and methyle hydrogen peroxide and peroxyacetic acid. The tropospheric sulfur oxidation pathway is therefore determined by cloud-water pH, dissolved [Fe2+] or [Mn2+] content, S emission rate, meteorological condition, and other factors. The S isotope composition is a good tracer for the source while the O isotopes, especially the triple O isotope compositions are a good tracer for S oxidation pathway. Jerkins and Bao (2006) provided the first set of multiple stable isotope compositions (δ34S, δ18O and Δ17O) for SAS collected from bulk atmosphere in Baton Rouge in the relatively rural southern USA. Their study revealed a long-tern average Δ17O value of ~+0.7‰ for SAS, and speculated that much of the Earth mid-latitudes may have a similar average SAS Δ17O value. Additional sampling campaign at different sites is necessarily for constructing and testing models on sulfur oxidation and transport in the troposphere. A total of 33 sulfate samples were collected from bulk atmospheric deposition over a 950-day period from May 2009 to December 2011 in the city of Wuhan, Hubei Province, China. Differing from Baton Rouge, Wuhan is an industrial metropolis with a population of 9.8 million and a high particulate matter content (115 μg/m3). It also has a subtropical monsoon climate, with rainwater pH at ~5.3 year-around. The rainwater ion concentrations have seasonal variations, typically low in summer and high in winter. The anions are dominated by SO42-, at an average concentration of 8.5 mg/L. There is little sulfate contribution from sea-salt (SS) sulfate or dusts in Wuhan. The isotopic compositions for bulk atmospheric sulfate

  6. Using multiple sulfur isotopes to link biological isotope fractionation in a sedimentary protolith to a magmatic Ni-sulfide deposit: Voisey's Bay Ni deposit, Labrador, Canada

    NASA Astrophysics Data System (ADS)

    Hiebert, R. S.; Bekker, A.; Wing, B. A.

    2012-12-01

    It is generally accepted that crustal contamination is required for the formation of significant magmatic Ni-Cu-PGE sulfide deposits. Either the addition of external S or SiO2 promote early sulfide saturation. The most direct indicator of S addition by this contaminant is S isotopes. However, the traditional use of δ34S values is inadequate in deposits where Archean sedimentary sulfides incorporated into these deposits might not have significantly different δ34S values from those of mantle S. Even in sediments that have variable δ34S values, δ34S signature can be reset to magmatic values by equilibrating large amounts of silicate magma with initial sulfide melt. However, sedimentary rocks contain isotope evidence of biological fractionation processes in the relationship between δ33S and δ34S values. We used multiple S isotope data to constrain the relationship between δ33S and δ34S values, identify biological S isotope fractionation in the metamorphosed sedimentary rocks of the Tasiuyak Gneiss, and compare this relationship to that in the Voisey's Bay magmatic Ni-deposit. The Voisey's Bay Ni-sulfide deposit, Labrador is hosted by a troctolitic conduit system. The Voisey's Bay intrusion is a part of the Nain plutonic suite and intruded at approximately 1.3 Ga along the boundary between the Proterozoic Tasiuyak Gneiss of the Churchill province and Archean gneisses of the Nain province. The general model suggests assimilation of a large amount of sulfidic Tasiuyak gneiss, leading to sulfur saturation prior to emplacement, even though the Tasiuyak gneiss does not have a high concentration of sulfur. High-temperature equilibrium relationships are not present in our measured δ33S and δ34S values from the Voisey's Bay deposit. Instead they indicate that a kinetic process is responsible for S isotope fractionations in the mineralization and troctolite, similar to that recorded by the Tasiuyak gneiss. The observed relationship between δ33S and δ34S values is

  7. Multiple oxygen and sulfur isotopic analyses on water-soluble sulfate in bulk atmospheric deposition from the southwestern United States

    USGS Publications Warehouse

    Bao, H.; Reheis, M.C.

    2003-01-01

    Sulfate is a major component of bulk atmospheric deposition (including dust, aerosol, fog, and rain). We analyzed sulfur and oxygen isotopic compositions of water-soluble sulfate from 40 sites where year-round dust traps collect bulk atmospheric deposition in the southwestern United States. Average sulfur and oxygen isotopic compositions (??34S and ??18O) are 5.8 ?? 1.4 (CDT) and 11.2 ?? 1.9 (SMOW) (n = 47), respectively. Samples have an oxygen 17 anomaly (?? 17O), with an average value of 1.0 ?? 0.6???. Except for a weak positive correlation between ??18O and ??17O values (r2 ??? 0.4), no correlation exists for ??18O versus ??34S, ?? 17O versus ??34S, or any of the three isotopic compositions versus elevation of the sample site. Exceptional positive ?? 17O values (up to 4.23???) are found in samples from sites in the vicinity of large cities or major highways, and near-zero ?? 17O values are found in samples close to dry lakes. Comparison of isotopic values of dust trap sulfate and desert varnish sulfate from the region reveals that varnish sulfate has average isotopic values that are ???4.8??? lower for ??18O, ???2.1??? higher for ??34S , and ???0.3??? lower for ?? 17O than those of the present-day bulk deposition sulfate. Although other factors could cause the disparity, this observation suggests a possibility that varnish sulfate may have recorded a long-term atmospheric sulfate deposition during the Holocene or Pleistocene, as well as the differences between sulfur and oxygen isotopic compositions of the preindustrial bulk deposition sulfate and those of the industrial era.

  8. Multiple oxygen and sulfur isotopic analyses on water-soluble sulfate in bulk atmospheric deposition from the southwestern United States

    NASA Astrophysics Data System (ADS)

    Bao, Huiming; Reheis, Marith C.

    2003-07-01

    Sulfate is a major component of bulk atmospheric deposition (including dust, aerosol, fog, and rain). We analyzed sulfur and oxygen isotopic compositions of water-soluble sulfate from 40 sites where year-round dust traps collect bulk atmospheric deposition in the southwestern United States. Average sulfur and oxygen isotopic compositions (δ34S and δ18O) are 5.8 ± 1.4 (CDT) and 11.2 ± 1.9 (SMOW) (n = 47), respectively. Samples have an oxygen 17 anomaly (Δ17O), with an average value of 1.0 ± 0.6‰. Except for a weak positive correlation between δ18O and Δ17O values (r2 ≈ 0.4), no correlation exists for δ18O versus δ34S, Δ17O versus δ34S, or any of the three isotopic compositions versus elevation of the sample site. Exceptional positive Δ17O values (up to 4.23‰) are found in samples from sites in the vicinity of large cities or major highways, and near-zero Δ17O values are found in samples close to dry lakes. Comparison of isotopic values of dust trap sulfate and desert varnish sulfate from the region reveals that varnish sulfate has average isotopic values that are ˜4.8‰ lower for δ18O, ˜2.1‰ higher for δ34S, and ˜0.3‰ lower for Δ17O than those of the present-day bulk deposition sulfate. Although other factors could cause the disparity, this observation suggests a possibility that varnish sulfate may have recorded a long-term atmospheric sulfate deposition during the Holocene or Pleistocene, as well as the differences between sulfur and oxygen isotopic compositions of the preindustrial bulk deposition sulfate and those of the industrial era.

  9. Multiple sulfur isotope signatures of sulfite and thiosulfate reduction by the model dissimilatory sulfate-reducer, Desulfovibrio alaskensis str. G20

    PubMed Central

    Leavitt, William D.; Cummins, Renata; Schmidt, Marian L.; Sim, Min S.; Ono, Shuhei; Bradley, Alexander S.; Johnston, David T.

    2014-01-01

    Dissimilatory sulfate reduction serves as a key metabolic carbon remineralization process in anoxic marine environments. Sulfate reducing microorganisms can impart a wide range in mass-dependent sulfur isotopic fractionation. As such, the presence and relative activity of these organisms is identifiable from geological materials. By extension, sulfur isotope records are used to infer the redox balance of marine sedimentary environments, and the oxidation state of Earth's oceans and atmosphere. However, recent work suggests that our understanding of microbial sulfate reduction (MSRs) may be missing complexity associated with the presence and role of key chemical intermediates in the reductive process. This study provides a test of proposed metabolic models of sulfate reduction by growing an axenic culture of the well-studied MSRs, Desulfovibrio alaskensis strain G20, under electron donor limited conditions on the terminal electron acceptors sulfate, sulfite or thiosulfate, and tracking the multiple S isotopic consequences of each condition set. The dissimilatory reduction of thiosulfate and sulfite produce unique minor isotope effects, as compared to the reduction of sulfate. Further, these experiments reveal a complex biochemistry associated with sulfite reduction. That is, under high sulfite concentrations, sulfur is shuttled to an intermediate pool of thiosulfate. Site-specific isotope fractionation (within thiosulfate) is very large (34ε ~ 30‰) while terminal product sulfide carries only a small fractionation from the initial sulfite (34ε < 10‰): a signature similar in magnitude to sulfate and thiosulfate reduction. Together these findings show that microbial sulfate reduction (MSR) is highly sensitive to the concentration of environmentally important sulfur-cycle intermediates (sulfite and thiosulfate), especially when thiosulfate and the large site-specific isotope effects are involved. PMID:25505449

  10. Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere.

    PubMed

    Muller, Élodie; Philippot, Pascal; Rollion-Bard, Claire; Cartigny, Pierre

    2016-07-01

    Sulfur isotopic anomalies (∆(33)S and ∆(36)S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2- and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ(34)S values at ∼+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of ∆(33)S between -1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ(34)S peak at +9‰ is associated with non-(33)S-anomalous barites displaying negative ∆(36)S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere.

  11. Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere.

    PubMed

    Muller, Élodie; Philippot, Pascal; Rollion-Bard, Claire; Cartigny, Pierre

    2016-07-01

    Sulfur isotopic anomalies (∆(33)S and ∆(36)S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2- and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ(34)S values at ∼+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of ∆(33)S between -1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ(34)S peak at +9‰ is associated with non-(33)S-anomalous barites displaying negative ∆(36)S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere. PMID:27330111

  12. Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere

    NASA Astrophysics Data System (ADS)

    Muller, Élodie; Philippot, Pascal; Rollion-Bard, Claire; Cartigny, Pierre

    2016-07-01

    Sulfur isotopic anomalies (∆33S and ∆36S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2- and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ34S values at ˜+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of ∆33S between -1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ34S peak at +9‰ is associated with non-33S-anomalous barites displaying negative ∆36S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere.

  13. Multiple sulfur-isotope signatures in Archean sulfates and their implications for the chemistry and dynamics of the early atmosphere

    NASA Astrophysics Data System (ADS)

    Muller, Élodie; Philippot, Pascal; Rollion-Bard, Claire; Cartigny, Pierre

    2016-07-01

    Sulfur isotopic anomalies (∆33S and ∆36S) have been used to trace the redox evolution of the Precambrian atmosphere and to document the photochemistry and transport properties of the modern atmosphere. Recently, it was shown that modern sulfate aerosols formed in an oxidizing atmosphere can display important isotopic anomalies, thus questioning the significance of Archean sulfate deposits. Here, we performed in situ 4S-isotope measurements of 3.2- and 3.5-billion-year (Ga)-old sulfates. This in situ approach allows us to investigate the diversity of Archean sulfate texture and mineralogy with unprecedented resolution and from then on to deconvolute the ocean and atmosphere Archean sulfur cycle. A striking feature of our data is a bimodal distribution of δ34S values at ˜+5‰ and +9‰, which is matched by modern sulfate aerosols. The peak at +5‰ represents barite of different ages and host-rock lithology showing a wide range of ∆33S between ‑1.77‰ and +0.24‰. These barites are interpreted as primary volcanic emissions formed by SO2 photochemical processes with variable contribution of carbonyl sulfide (OCS) shielding in an evolving volcanic plume. The δ34S peak at +9‰ is associated with non–33S-anomalous barites displaying negative ∆36S values, which are best interpreted as volcanic sulfate aerosols formed from OCS photolysis. Our findings confirm the occurrence of a volcanic photochemical pathway specific to the early reduced atmosphere but identify variability within the Archean sulfate isotope record that suggests persistence throughout Earth history of photochemical reactions characteristic of the present-day stratosphere.

  14. Multiple sulfur isotope fractionation and mass transfer processes during pyrite precipitation and recrystallization: An experimental study at 300 and 350 °C

    NASA Astrophysics Data System (ADS)

    Syverson, Drew D.; Ono, Shuhei; Shanks, Wayne C.; Seyfried, William E.

    2015-09-01

    Equilibrium multiple sulfur isotope fractionation factors (33S/32S and 34S/32S) between aqueous SO4, H2S, and coexisting pyrite under hydrothermal conditions were determined experimentally at 300-350 °C and 500 bars. Two different experimental techniques were used to determine the fractionation factors and the rate of S isotope exchange between pyrite and constituent aqueous species, H2S and SO4; (1) closed system gold capsule pyrite-H2S exchange experiments and (2) complimentary time-series experiments at 300 and 350 °C, 500 bars using flexible gold cell hydrothermal equipment, which allowed monitoring the multiple S isotope composition of dissolved S species during pyrite precipitation and subsequent recrystallization. The three isotope technique was applied to the multiple S isotope data to demonstrate equilibrium S isotope fractionation between pyrite and H2S. Results at 350 °C indicate ln34αPyrite/H2S = -1.9‰ and ln33αPyrite/H2S = -1.0‰. The ln34αPyrite/H2S is not only different in magnitude but also in sign from the commonly used value of 1‰ from Ohmoto and Rye (1979). This experimental study also demonstrated initial S isotope disequilibrium amongst the aqueous S-species and pyrite during rapid precipitation, despite aqueous speciation indicating pyrite saturation at all stages. Textural, crystallographic, and S isotope interpretations suggest that pyrite formed by means of the FeS pathway. The initial S isotope disequilibrium between formed pyrite and dissolved S-species was effectively erased and approached isotopic equilibrium upon recrystallization during the course of 4297 h. Interpretation of seafloor hydrothermal vent sulfides using the revised equilibrium 34S/32S fractionation between pyrite and H2S suggests that pyrite is close to S isotope equilibrium with vent H2S, contrary to previous conclusions. The experimental data reported here broaden the range of pyrite formation mechanisms at seafloor hydrothermal vents, in that mineral

  15. Multiple sulfur isotope and mineralogical constraints on the genesis of Ni-Cu-PGE magmatic sulfide mineralization of the Monchegorsk Igneous Complex, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Bekker, A.; Grokhovskaya, T. L.; Hiebert, R.; Sharkov, E. V.; Bui, T. H.; Stadnek, K. R.; Chashchin, V. V.; Wing, B. A.

    2015-08-01

    We present the results of a pilot investigation of multiple sulfur isotopes for the Ni-Cu-PGE sulfide mineralization of the ˜2.5 Ga Monchegorsk Igneous Complex (MIC). Base Metal Sulfide (BMS) compositions, Platinum Group Element (PGE) distributions, and Platinum Group Mineral (PGM) assemblages were also studied for different types of Ni-Cu-PGE mineralization. The uniformly low S content of the country rocks for the MIC as well as variable Sm-Nd isotope systematics and low-sulfide, PGE-rich mineralization of the MIC suggest that S saturation was reached via assimilation of silicates rather than assimilation of sulfur-rich lithologies. R-factor modeling suggests that the mixing ratio for silicate-to-sulfide melt was very high, well above 15,000 for the majority of our mineralized samples, as might be expected for the low-sulfide, PGE-rich mineralization of the MIC. Small, negative Δ33S values (from -0.23 to -0.04 ‰) for sulfides in strongly metamorphosed MIC-host rocks indicate that their sulfur underwent mass-independent sulfur isotope fractionation (MIF) in the oxygen-poor Archean atmosphere before it was incorporated into the protoliths of the host paragneisses and homogenized during metamorphism. Ore minerals from the MIC have similar Δ33S values (from -0.21 to -0.06 ‰) consistent with country rock assimilation contributing to sulfide saturation, but, also importantly, our dataset suggests that Δ33S values decrease from the center to the margin of the MIC as well as from early to late magmatic phases, potentially indicating that both local assimilation of host rocks and S homogenization in the central part of the large intrusion took place.

  16. Seawater sulfur isotope fluctuations in the Cretaceous.

    PubMed

    Paytan, Adina; Kastner, Miriam; Campbell, Douglas; Thiemens, Mark H

    2004-06-11

    The exogenic sulfur cycle is tightly coupled with the carbon and oxygen cycles, and therefore a central component of Earth's biogeochemistry. Here we present a high-resolution record of the sulfur isotopic composition of seawater sulfate for the Cretaceous. The general enrichment of isotopically light sulfur that prevailed during the Cretaceous may have been due to increased volcanic and hydrothermal activity. Two excursions toward isotopically lighter sulfur represent periods of lower rates of pyrite burial, implying a shift in the location of organic carbon burial to terrestrial or open-ocean settings. The concurrent changes in seawater sulfur and inorganic carbon isotopic compositions imply short-term variability in atmospheric oxygen partial pressure.

  17. Sulfur isotopic composition of cenozoic seawater sulfate

    PubMed

    Paytan; Kastner; Campbell; Thiemens

    1998-11-20

    A continuous seawater sulfate sulfur isotope curve for the Cenozoic with a resolution of approximately 1 million years was generated using marine barite. The sulfur isotopic composition decreased from 19 to 17 per mil between 65 and 55 million years ago, increased abruptly from 17 to 22 per mil between 55 and 45 million years ago, remained nearly constant from 35 to approximately 2 million years ago, and has decreased by 0.8 per mil during the past 2 million years. A comparison between seawater sulfate and marine carbonate carbon isotope records reveals no clear systematic coupling between the sulfur and carbon cycles over one to several millions of years, indicating that changes in the burial rate of pyrite sulfur and organic carbon did not singularly control the atmospheric oxygen content over short time intervals in the Cenozoic. This finding has implications for the modeling of controls on atmospheric oxygen concentration.

  18. Sulfur isotope distribution in solfatares, Yellowstone National Park

    USGS Publications Warehouse

    Schoen, R.; Rye, R.O.

    1970-01-01

    Sulfur isotope data on hydrogen sulfide, native sulfur, and sulfates from acid hot-spring areas at Yellowstone National Park suggest that hydrogen sulfide oxidizes to sulfur analogically, whereas sulfur undergoes biological oxidation to sulfuric acid. An exception occurs at Mammoth Hot Springs where hydrogen sulfide apparently undergoes biochemical oxidation to sulfur.

  19. Sulfur isotope homogeneity of lunar mare basalts

    NASA Astrophysics Data System (ADS)

    Wing, Boswell A.; Farquhar, James

    2015-12-01

    We present a new set of high precision measurements of relative 33S/32S, 34S/32S, and 36S/32S values in lunar mare basalts. The measurements are referenced to the Vienna-Canyon Diablo Troilite (V-CDT) scale, on which the international reference material, IAEA-S-1, is characterized by δ33S = -0.061‰, δ34S ≡ -0.3‰ and δ36S = -1.27‰. The present dataset confirms that lunar mare basalts are characterized by a remarkable degree of sulfur isotopic homogeneity, with most new and published SF6-based sulfur isotope measurements consistent with a single mass-dependent mean isotopic composition of δ34S = 0.58 ± 0.05‰, Δ33S = 0.008 ± 0.006‰, and Δ36S = 0.2 ± 0.2‰, relative to V-CDT, where the uncertainties are quoted as 99% confidence intervals on the mean. This homogeneity allows identification of a single sample (12022, 281) with an apparent 33S enrichment, possibly reflecting cosmic-ray-induced spallation reactions. It also reveals that some mare basalts have slightly lower δ34S values than the population mean, which is consistent with sulfur loss from a reduced basaltic melt prior to eruption at the lunar surface. Both the sulfur isotope homogeneity of the lunar mare basalts and the predicted sensitivity of sulfur isotopes to vaporization-driven fractionation suggest that less than ≈1-10% of lunar sulfur was lost after a potential moon-forming impact event.

  20. The Fate of Sulfur in Late-Stage Magmatic Processes: Insights From Quadruple Sulfur Isotopes

    NASA Astrophysics Data System (ADS)

    Keller, N. S.; Ono, S.; Shaw, A. M.

    2009-05-01

    Multiple sulfur isotopes (32S, 33S, 34S and 36S) have recently been shown to be useful tracers of fluid-rock interaction in seafloor hydrothermal systems [1]. Here we present the application of multiple sulfur isotopes to subaerial volcanoes with the aim of unraveling the various processes fractionating sulfur in the upper volcanic system. We take advantage of the fact that the ascent of volcanic gases through a hydrothermal system causes complex isotopic fractionation between the quaduple sulfur isotopes. δ34S is thought to trace the source of sulfur as well as magma degassing; at equilibrium, δ33S follows a mass-dependent fractionation relationship such that two phases in equilibrium with each other have equal Δ33S values (Δ33S ≡ ln(δ33S+1) - 0.515×ln(δ34S+1)). Disequilibrium Δ33S values can indicate isotope mixing and other fluid-rock interactions. The ultimate aim of this study is to assess the use of quadruple sulfur isotopes to obtain quantitative information on the sulfur cycle at convergent plate margins. The sulfur mass balance at convergent margins is poorly constrained, partly because late-stage processes are challenging to quantify and lead to large uncertainties in the global output fluxes. Quadruple sulfur isotopes provide a powerful tool to untangle the convoluted history of volcanic systems. Here we report the first quadruple sulfur isotopic values for H2S, SO2 and native sulfur from arc volcanoes. Fumarolic gases (˜100°C) and sulfur sublimates were collected from Poas and Turrialba, two actively degassing volcanoes in Costa Rica. The gases were bubbled in situ through chemical traps to separate H2S from SO2: H2S was reacted to form ZnS, and SO2 to form BaSO4. Sulfur was chemically extracted from the solid phases and precipitated as Ag2S, which was fluorinated to SF6 and analysed by IRMS. Poas and Turrialba have H2S/SO2 ˜1 and 0.01, respectively. δ34SH2S and δ34SSO2 are similar to gases measured at other arcs [2], - 7.9‰ and 0.6

  1. Sulfur Isotope Effects of Dissimilatory Sulfite Reductase.

    PubMed

    Leavitt, William D; Bradley, Alexander S; Santos, André A; Pereira, Inês A C; Johnston, David T

    2015-01-01

    The precise interpretation of environmental sulfur isotope records requires a quantitative understanding of the biochemical controls on sulfur isotope fractionation by the principle isotope-fractionating process within the S cycle, microbial sulfate reduction (MSR). Here we provide the only direct observation of the major ((34)S/(32)S) and minor ((33)S/(32)S, (36)S/(32)S) sulfur isotope fractionations imparted by a central enzyme in the energy metabolism of sulfate reducers, dissimilatory sulfite reductase (DsrAB). Results from in vitro sulfite reduction experiments allow us to calculate the in vitro DsrAB isotope effect in (34)S/(32)S (hereafter, [Formula: see text]) to be 15.3 ± 2‰, 2σ. The accompanying minor isotope effect in (33)S, described as [Formula: see text], is calculated to be 0.5150 ± 0.0012, 2σ. These observations facilitate a rigorous evaluation of the isotopic fractionation associated with the dissimilatory MSR pathway, as well as of the environmental variables that govern the overall magnitude of fractionation by natural communities of sulfate reducers. The isotope effect induced by DsrAB upon sulfite reduction is a factor of 0.3-0.6 times prior indirect estimates, which have ranged from 25 to 53‰ in (34)εDsrAB. The minor isotope fractionation observed from DsrAB is consistent with a kinetic or equilibrium effect. Our in vitro constraints on the magnitude of [Formula: see text] is similar to the median value of experimental observations compiled from all known published work, where (34)ε r-p = 16.1‰ (r-p indicates reactant vs. product, n = 648). This value closely matches those of MSR operating at high sulfate reduction rates in both laboratory chemostat experiments ([Formula: see text] 17.3 ± 1.5‰, 2σ) and in modern marine sediments ([Formula: see text] 17.3 ± 3.8‰). Targeting the direct isotopic consequences of a specific enzymatic processes is a fundamental step toward a biochemical foundation for reinterpreting the

  2. Sulfur Isotope Effects of Dissimilatory Sulfite Reductase

    PubMed Central

    Leavitt, William D.; Bradley, Alexander S.; Santos, André A.; Pereira, Inês A. C.; Johnston, David T.

    2015-01-01

    The precise interpretation of environmental sulfur isotope records requires a quantitative understanding of the biochemical controls on sulfur isotope fractionation by the principle isotope-fractionating process within the S cycle, microbial sulfate reduction (MSR). Here we provide the only direct observation of the major (34S/32S) and minor (33S/32S, 36S/32S) sulfur isotope fractionations imparted by a central enzyme in the energy metabolism of sulfate reducers, dissimilatory sulfite reductase (DsrAB). Results from in vitro sulfite reduction experiments allow us to calculate the in vitro DsrAB isotope effect in 34S/32S (hereafter, 34εDsrAB) to be 15.3 ± 2‰, 2σ. The accompanying minor isotope effect in 33S, described as 33λDsrAB, is calculated to be 0.5150 ± 0.0012, 2σ. These observations facilitate a rigorous evaluation of the isotopic fractionation associated with the dissimilatory MSR pathway, as well as of the environmental variables that govern the overall magnitude of fractionation by natural communities of sulfate reducers. The isotope effect induced by DsrAB upon sulfite reduction is a factor of 0.3–0.6 times prior indirect estimates, which have ranged from 25 to 53‰ in 34εDsrAB. The minor isotope fractionation observed from DsrAB is consistent with a kinetic or equilibrium effect. Our in vitro constraints on the magnitude of 34εDsrAB is similar to the median value of experimental observations compiled from all known published work, where 34εr−p = 16.1‰ (r–p indicates reactant vs. product, n = 648). This value closely matches those of MSR operating at high sulfate reduction rates in both laboratory chemostat experiments (34εSO4−H2S =  17.3 ± 1.5‰, 2σ) and in modern marine sediments (34εSO4−H2S =  17.3 ± 3.8‰). Targeting the direct isotopic consequences of a specific enzymatic processes is a fundamental step toward a biochemical foundation for reinterpreting the biogeochemical and geobiological sulfur isotope records in

  3. Effect of electron donors on the fractionation of sulfur isotopes by a marine Desulfovibrio sp.

    NASA Astrophysics Data System (ADS)

    Sim, Min Sub; Ono, Shuhei; Donovan, Katie; Templer, Stefanie P.; Bosak, Tanja

    2011-08-01

    Sulfur isotope effects produced by microbial dissimilatory sulfate reduction are used to reconstruct the coupled cycling of carbon and sulfur through geologic time, to constrain the evolution of sulfur-based metabolisms, and to track the oxygenation of Earth's surface. In this study, we investigate how the coupling of carbon and sulfur metabolisms in batch and continuous cultures of a recently isolated marine sulfate reducing bacterium DMSS-1, a Desulfovibrio sp ., influences the fractionation of sulfur isotopes. DMSS-1 grown in batch culture on seven different electron donors (ethanol, glycerol, fructose, glucose, lactate, malate and pyruvate) fractionates 34S/ 32S ratio from 6‰ to 44‰, demonstrating that the fractionations by an actively growing culture of a single incomplete oxidizing sulfate reducing microbe can span almost the entire range of previously reported values in defined cultures. The magnitude of isotope effect correlates well with cell specific sulfate reduction rates (from 0.7 to 26.1 fmol/cell/day). DMSS-1 grown on lactate in continuous culture produces a larger isotope effect (21-37‰) than the lactate-grown batch culture (6‰), indicating that the isotope effect also depends on the supply rate of the electron donor and microbial growth rate. The largest isotope effect in continuous culture is accompanied by measurable changes in cell length and cellular yield that suggest starvation. The use of multiple sulfur isotopes in the model of metabolic fluxes of sulfur shows that the loss of sulfate from the cell and the intracellular reoxidation of reduced sulfur species contribute to the increase in isotope effects in a correlated manner. Isotope fractionations produced during sulfate reduction in the pure culture of DMSS-1 expand the previously reported range of triple sulfur isotope effects ( 32S, 33S, and 34S) by marine sulfate reducing bacteria, implying that microbial sulfur disproportionation may have a smaller 33S isotopic fingerprint

  4. Anomalous fractionations of sulfur isotopes during thermochemical sulfate reduction.

    PubMed

    Watanabe, Yumiko; Farquhar, James; Ohmoto, Hiroshi

    2009-04-17

    Anomalously fractionated sulfur isotopes in many sedimentary rocks older than 2.4 billion years have been widely believed to be the products of ultraviolet photolysis of volcanic sulfur dioxide in an anoxic atmosphere. Our laboratory experiments have revealed that reduced-sulfur species produced by reactions between powders of amino acids and sulfate at 150 degrees to 200 degrees C possess anomalously fractionated sulfur isotopes: Delta33S = +0.1 to +2.1 per mil and Delta36S = -1.1 to +1.1 per mil. These results suggest that reactions between organic matter in sediments and sulfate-rich hydrothermal solutions may have produced anomalous sulfur isotope signatures in some sedimentary rocks. If so, the sulfur isotope record of sedimentary rocks may be linked to the biological and thermal evolution of Earth in ways different than previously thought.

  5. Triple sulfur isotope composition of Late Archean seawater sulfate

    NASA Astrophysics Data System (ADS)

    Paris, G.; Fischer, W. W.; Sessions, A. L.; Adkins, J. F.

    2013-12-01

    Multiple sulfur isotope ratios in Archean sedimentary rocks have provided powerful insights into the behavior of the ancient sulfur cycle, the redox state of fluid Earth, and the timing of the rise of atmospheric oxygen [1]. Most processes fractionate sulfur isotopes in proportion to their mass differences, but the Archean sulfur isotope record is marked by pronounced mass-independent fractionation (MIF, Δ33S≠0). The origin of these signatures has been traditionally interpreted as the result of photolysis of SO2 from short wavelength UV light, with positive Δ33S values recorded in pyrite and negative Δ33S values in sulfate-bearing phases [2]. This long-held hypothesis rests on observations of negative Δ33S from enigmatic barite occurrences from mixed volcanic sedimentary strata in Mesoarchean greenstone terrains. Despite forming the framework for understanding Archean sulfur cycle processes [3], it is largely untested [3]. It is largely untested. Consequently, the biggest challenge to our current understanding of the early sulfur cycle is a poor understanding of the isotopic composition of seawater sulfate. Sulfate evaporite minerals are absent from Archean strata and the sulfur isotope record is written entirely by measurements of pyrite. Carbonate associated sulfate (CAS) provides an important archive for assaying the isotopic composition of ancient seawater sulfate It has been exploited in many studies of Phanerozoic and Proterozoic sulfate but have been only marginally used thus far for Archean samples because of the extremely low concentration of CAS in limestones and dolomites from this era. We have developed a novel MC-ICP-MS approach to solve this problem [4]. This new method lowers the detection limit by up to three orders of magnitude for δ34S and Δ33S measurements, enabling to work on a few nmols of sulfate which represent only tens of mg of sample powders micromilled from specific carbonate textures. Two stratigraphic sections from the 2

  6. Sulfur Isotope Composition of Putative Primary Troilite in Chondrules

    NASA Technical Reports Server (NTRS)

    Tachibana, Shogo; Huss, Gary R.

    2002-01-01

    Sulfur isotope compositions of putative primary troilites in chondrules from Bishunpur were measured by ion probe. These primary troilites have the same S isotope compositions as matrix troilites and thus appear to be isotopically unfractionated. Additional information is contained in the original extended abstract.

  7. Isotopic inferences of ancient biochemistries - Carbon, sulfur, hydrogen, and nitrogen

    NASA Technical Reports Server (NTRS)

    Schidlowski, M.; Hayes, J. M.; Kaplan, I. R.

    1983-01-01

    In processes of biological incorporation and subsequent biochemical processing sizable isotope effects occur as a result of both thermodynamic and kinetic fractionations which take place during metabolic and biosynthetic reactions. In this chapter a review is provided of earlier work and recent studies on isotope fractionations in the biogeochemical cycles of carbon, sulfur, hydrogen, and nitrogen. Attention is given to the biochemistry of carbon isotope fractionation, carbon isotope fractionation in extant plants and microorganisms, isotope fractionation in the terrestrial carbon cycle, the effects of diagenesis and metamorphism on the isotopic composition of sedimentary carbon, the isotopic composition of sedimentary carbon through time, implications of the sedimentary carbon isotope record, the biochemistry of sulfur isotope fractionation, pathways of the biogeochemical cycle of nitrogen, and the D/H ratio in naturally occurring materials.

  8. Large sulfur isotope fractionation does not require disproportionation.

    PubMed

    Sim, Min Sub; Bosak, Tanja; Ono, Shuhei

    2011-07-01

    The composition of sulfur isotopes in sedimentary sulfides and sulfates traces the sulfur cycle throughout Earth's history. In particular, depletions of sulfur-34 ((34)S) in sulfide relative to sulfate exceeding 47 per mil (‰) often serve as a proxy for the disproportionation of intermediate sulfur species in addition to sulfate reduction. Here, we demonstrate that a pure, actively growing culture of a marine sulfate-reducing bacterium can deplete (34)S by up to 66‰ during sulfate reduction alone and in the absence of an extracellular oxidative sulfur cycle. Therefore, similar magnitudes of sulfur isotope fractionation in sedimentary rocks do not unambiguously record the presence of other sulfur-based metabolisms or the stepwise oxygenation of Earth's surface environment during the Proterozoic. PMID:21719675

  9. Large sulfur isotope fractionation does not require disproportionation.

    PubMed

    Sim, Min Sub; Bosak, Tanja; Ono, Shuhei

    2011-07-01

    The composition of sulfur isotopes in sedimentary sulfides and sulfates traces the sulfur cycle throughout Earth's history. In particular, depletions of sulfur-34 ((34)S) in sulfide relative to sulfate exceeding 47 per mil (‰) often serve as a proxy for the disproportionation of intermediate sulfur species in addition to sulfate reduction. Here, we demonstrate that a pure, actively growing culture of a marine sulfate-reducing bacterium can deplete (34)S by up to 66‰ during sulfate reduction alone and in the absence of an extracellular oxidative sulfur cycle. Therefore, similar magnitudes of sulfur isotope fractionation in sedimentary rocks do not unambiguously record the presence of other sulfur-based metabolisms or the stepwise oxygenation of Earth's surface environment during the Proterozoic.

  10. Microbially Mediated Kinetic Sulfur Isotope Fractionation: Reactive Transport Modeling Benchmark

    NASA Astrophysics Data System (ADS)

    Wanner, C.; Druhan, J. L.; Cheng, Y.; Amos, R. T.; Steefel, C. I.; Ajo Franklin, J. B.

    2014-12-01

    Microbially mediated sulfate reduction is a ubiquitous process in many subsurface systems. Isotopic fractionation is characteristic of this anaerobic process, since sulfate reducing bacteria (SRB) favor the reduction of the lighter sulfate isotopologue (S32O42-) over the heavier isotopologue (S34O42-). Detection of isotopic shifts have been utilized as a proxy for the onset of sulfate reduction in subsurface systems such as oil reservoirs and aquifers undergoing uranium bioremediation. Reactive transport modeling (RTM) of kinetic sulfur isotope fractionation has been applied to field and laboratory studies. These RTM approaches employ different mathematical formulations in the representation of kinetic sulfur isotope fractionation. In order to test the various formulations, we propose a benchmark problem set for the simulation of kinetic sulfur isotope fractionation during microbially mediated sulfate reduction. The benchmark problem set is comprised of four problem levels and is based on a recent laboratory column experimental study of sulfur isotope fractionation. Pertinent processes impacting sulfur isotopic composition such as microbial sulfate reduction and dispersion are included in the problem set. To date, participating RTM codes are: CRUNCHTOPE, TOUGHREACT, MIN3P and THE GEOCHEMIST'S WORKBENCH. Preliminary results from various codes show reasonable agreement for the problem levels simulating sulfur isotope fractionation in 1D.

  11. [Sulfur isotopic ratios indicating sulfur cycling in slope soils of karst areas].

    PubMed

    Zhang, Wei; Liu, Cong-qiang; Li, Xiao-dong; Liu, Tao-ze; Zhang, Li-li

    2010-02-01

    Sequential extraction methods for soil sulfur were used to determine delta34 S ratios and sulfur contents of total sulfur, organic sulfur, SO4(21) and FeS2 in slope soils of karst areas. In general, FeS2 has the lowest delta34 S ratios, ranging from -6.86% per hundred to -4.229% per hundred, followed in ascending order by SO4(2-) (-2.64% per hundred - -1.34% per hundred), total sulfur (-3.25% per hundred - -1.03% per hundred) and organic sulfur (-1.63% per hundred -0.50% per hundred) in surface soils of profiles, and delta34 S ratios in different sulfur forms all show increasing trend with profiles deepening. Covariations of delta34 S ratios of SO4(2-) and FeS2 with increasing depth are related to SO4(2-) dissimilatory reduction, while the increase in parallel of delta34 S ratios of total sulfur and organic sulfur could be resulted from organic sulfur cycling. delta34 S ratios have been extensively used to indicate sulfur sources, moreover, SO4(2-) dissimilatory reduction and organic sulfur mineralization result in significant sulfur isotopic fractionation, and sulfides oxidation and SO4(2-) assimilation have no isotopic fractionation occurred, the vertical variations of delta34 S ratios in different sulfur forms can therefore be good records for depth-dependant sulfur cycling processes. Furthermore, by comparing depth distributions of sulfur contents and delta34 S ratios in different sulfur forms, it is easily to discuss the migration of SO4(-1) and organic sulfur fractions in soil profiles.

  12. Isotopic composition and concentration of sulfur in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Gao, X.; Thiemens, M. H.

    1993-07-01

    New sulfur isotopic ratio measurements are reported for seven carbonaceous chondrites. Newly developed procedures permit measurement of delta S-33, delta S-34, and delta S-36 at precisions significantly greater than previously reported. A search for S-36 nucleosynthetic anomalies coproduced with anomalies in, for example, Ti-50 and Ca-48 was negative. The high endemic sulfur concentration probably dilutes any S-36 anomaly, and separation of individual sulfur phases may be needed to identify S-36 carrier phases. Large internal isotopic variations are observed, deriving from parent body and possibly nebular processes. Chondrule separates from Allende demonstrate isotopic compositions which vary as a function of diameter. High-temperature gas-solid exchange and a two-component mixing model may account for the observations. High-resolution isotopic data and structural information are reported for organic sulfur compounds separated by chemical extractions. The insoluble organics appear to be of either aliphatic or alicyclic structure and are dominant phases.

  13. Stratigraphic variation of sulfur isotopes in Colorado Corehole Number 1

    SciTech Connect

    Smith, J.W.; Young, N.B.

    1983-04-01

    Sulfur isotope distribution with stratigraphy is reported for organic and pyritic sulfur of Green River Formation oil shale samples selected to represent the 1600-foot (488 m) Parachute Creek Member in Colorado Corehole No. 1. In the saline zone where nahcolite and dawsonite occur in the oil shale and in the Mahogany zone the /sup 34/ values for organic sulfur and pyrite sulfur match with the pyrite sulfur slightly lighter than the organic sulfur. This is interpreted to demonstrate that organic matter supplied most of the sulfur to the sediment which became oil shale. Little sulfate reached the sediment so no sulfate reduction could occur to enrich the heavy sulfur isotope. No systematic increase in S/sup 34/ was detected in either pyrite or organic sulfur. A remarkably large increase in concentration of /sup 34/S occurring in a short stratigraphic span is demonstrated. This abrupt increase occurs near the middle of the Parachute Creek Member sediments. Above this point both pyrite and organic sulfur remain significantly enriched in /sup 34/S.

  14. Sulfur and hydrogen isotope anomalies in meteorite sulfonic acids.

    PubMed

    Cooper, G W; Thiemens, M H; Jackson, T L; Chang, S

    1997-08-22

    Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

  15. Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids

    NASA Technical Reports Server (NTRS)

    Cooper, George W.; Thiemens, Mark H.; Jackson, Teresa L.; Chang, Sherwood

    1997-01-01

    Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

  16. Sulfur isotope ratios as evidence of dissolved sulfur uptake by salt marsh cordgrass. [Spartina alterniflora

    SciTech Connect

    Carlson, P.R. Jr.; Forrest, J.

    1985-06-01

    The difference in stable sulfur isotope ratios of sulfate and sulfide in marsh porewater was used to verify the uptake of hydrogen sulfide by the salt marsh cordgrass, Spartina alterniflora, in North Carlina salt marsh. Most of the plant sulfur derived from porewater sulfide was recovered as sulfate indicating that the sulfide had been oxidized within the plant. The analysis of sulfur isotope ratios of other marsh halophytes is suggested as a technique to determine whether sulfide is taken up by plants. 15 refs., 2 figs., 1 tab.

  17. Sulfur isotope fractionation during the reduction of elemental sulfur and thiosulfate by Dethiosulfovibrio spp.

    NASA Astrophysics Data System (ADS)

    Surkov, A. V.; Böttcher, M. E.; Kuever, J.

    2009-04-01

    Thiosulfate and elemental sulfur are typical by-products of the oxidation of dissolved sulfide and important sulfur intermediates in the biogeochemical sulfur cycle of natural sediments where they can be further transformed by microbial or chemical oxidation, reduction, or disproportionation. Due to the often superimposing reaction pathways of the sulfur intermediates in natural environments specific tracers are needed to better resolve the complex microbial and biogeochemical reactions. An important fingerprint for sulfur cycling is provided by the microbial fractionation of the stable sulfur isotopes S-34 and S-32. Proper interpretation of isotope signals in nature, however, is only possible by the calibration with results obtained with pure cultures under defined experimental conditions. In addition, sulfur isotope discrimination may provide informations about specific encymatic biochemical pathways within the bacterial cells. In this study, we report the results for the discrimination of stable sulfur isotopes S-32 and S-34 during reduction of thiosulfate and elemental sulfur by non-sulfate, but sulfur- and thiosulfate-reducing bacteria which are phylogenetically not related to sulfate-reducing bacteria. Experiments with were conducted at known cell-specific thiosulfate reduction rates. Stable sulfur isotope fractionation was investigated during reduction of thiosulfate and elemental sulfur at 28°C by growing batch cultures of Dethiosulfovibrio marinus WS100 (type strain DSM 12537) and Dethiosulfovibrio russensis (type strain DSM 12538) using citrate as carbon and energy source. The cell-specific reduction rates were 0.3 to 2.4 fmol cell-1 d-1 (thiosulfate) and 31 to 38 fmol cell-1 d-1 (elemental sulphur), respectively. The sulfide produced was depleted in S-34 by 12 per mil compared to total thiosulfate sulfur, close to previous results observed for sulfate-reducing bacteria, indicating that the thiosulfate-reducing mechanism of sulfate reducers is similar to

  18. Theoretical estimation of equilibrium sulfur isotope fractionations among aqueous sulfite species: Implications for isotope models of microbial sulfate reduction

    NASA Astrophysics Data System (ADS)

    Eldridge, D. L.; Farquhar, J.; Guo, W.

    2015-12-01

    Sulfite (sensu lato), an intermediate in a variety sulfur redox processes, plays a particularly important role in microbial sulfate reduction. It exists intracellularly as multiple species between sets of enzymatic reactions that transform sulfate to sulfide, with the exact speciation depending on pH, T, and ionic strength. However, the complex speciation of sulfite is ignored in current isotope partitioning models of microbial sulfate reduction and simplified solely to the pyramidal SO32- (sulfite sensu stricto), due to a lack of appropriate constraints. We theoretically estimated the equilibrium sulfur isotope fractionations (33S/32S, 34S/32S, 36S/32S) among all documented sulfite species in aqueous solution, including sulfite (SO32-), bisulfite isomers and dimers ((HS)O3-, (HO)SO2-, S2O52-), and SO2(aq), through first principles quantum mechanical calculations. The calculations were performed at B3LYP/6-31+G(d,p) level using cluster models with 30-40 water molecules surrounding the solute. Our calculated equilibrium fractionation factors compare well to the available experimental constraints and suggest that the minor and often-ignored tetrahedral (HS)O3- isomer of bisulfite strongly influences isotope partitioning behavior in the sulfite system under most environmentally relevant conditions, particularly fractionation magnitudes and unusual temperature dependence. For example, we predict that sulfur isotope fractionation between sulfite and bulk bisulfite in solution should have an apparent inverse temperature dependence due to the influence of (HS)O3- and its increased stability at higher temperatures. Our findings highlight the need to appropriately account for speciation/isomerization of sulfur species in sulfur isotope studies. We will also present similar calculation results of other aqueous sulfur compounds (e.g., H2S/HS-, SO42-, S2O32-, S3O62-, and poorly documented SO22- species), and discuss the implication of our results for microbial sulfate

  19. Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle.

    PubMed

    Canfield, Donald E

    2013-05-21

    Sulfate is the second most abundant anion (behind chloride) in modern seawater, and its cycling is intimately coupled to the cycling of organic matter and oxygen at the Earth's surface. For example, the reduction of sulfide by microbes oxidizes vast amounts of organic carbon and the subsequent reaction of sulfide with iron produces pyrite whose burial in sediments is an important oxygen source to the atmosphere. The concentrations of seawater sulfate and the operation of sulfur cycle have experienced dynamic changes through Earth's history, and our understanding of this history is based mainly on interpretations of the isotope record of seawater sulfates and sedimentary pyrites. The isotope record, however, does not give a complete picture of the ancient sulfur cycle. This is because, in standard isotope mass balance models, there are more variables than constraints. Typically, in interpretations of the isotope record and in the absence of better information, one assumes that the isotopic composition of the input sulfate to the oceans has remained constant through time. It is argued here that this assumption has a constraint over the last 390 Ma from the isotopic composition of sulfur in coal. Indeed, these compositions do not deviate substantially from the modern surface-water input to the oceans. When applied to mass balance models, these results support previous interpretations of sulfur cycle operation and counter recent suggestions that sulfate has been a minor player in sulfur cycling through the Phanerozoic Eon. PMID:23650346

  20. Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle.

    PubMed

    Canfield, Donald E

    2013-05-21

    Sulfate is the second most abundant anion (behind chloride) in modern seawater, and its cycling is intimately coupled to the cycling of organic matter and oxygen at the Earth's surface. For example, the reduction of sulfide by microbes oxidizes vast amounts of organic carbon and the subsequent reaction of sulfide with iron produces pyrite whose burial in sediments is an important oxygen source to the atmosphere. The concentrations of seawater sulfate and the operation of sulfur cycle have experienced dynamic changes through Earth's history, and our understanding of this history is based mainly on interpretations of the isotope record of seawater sulfates and sedimentary pyrites. The isotope record, however, does not give a complete picture of the ancient sulfur cycle. This is because, in standard isotope mass balance models, there are more variables than constraints. Typically, in interpretations of the isotope record and in the absence of better information, one assumes that the isotopic composition of the input sulfate to the oceans has remained constant through time. It is argued here that this assumption has a constraint over the last 390 Ma from the isotopic composition of sulfur in coal. Indeed, these compositions do not deviate substantially from the modern surface-water input to the oceans. When applied to mass balance models, these results support previous interpretations of sulfur cycle operation and counter recent suggestions that sulfate has been a minor player in sulfur cycling through the Phanerozoic Eon.

  1. Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle

    PubMed Central

    Canfield, Donald E.

    2013-01-01

    Sulfate is the second most abundant anion (behind chloride) in modern seawater, and its cycling is intimately coupled to the cycling of organic matter and oxygen at the Earth’s surface. For example, the reduction of sulfide by microbes oxidizes vast amounts of organic carbon and the subsequent reaction of sulfide with iron produces pyrite whose burial in sediments is an important oxygen source to the atmosphere. The concentrations of seawater sulfate and the operation of sulfur cycle have experienced dynamic changes through Earth’s history, and our understanding of this history is based mainly on interpretations of the isotope record of seawater sulfates and sedimentary pyrites. The isotope record, however, does not give a complete picture of the ancient sulfur cycle. This is because, in standard isotope mass balance models, there are more variables than constraints. Typically, in interpretations of the isotope record and in the absence of better information, one assumes that the isotopic composition of the input sulfate to the oceans has remained constant through time. It is argued here that this assumption has a constraint over the last 390 Ma from the isotopic composition of sulfur in coal. Indeed, these compositions do not deviate substantially from the modern surface-water input to the oceans. When applied to mass balance models, these results support previous interpretations of sulfur cycle operation and counter recent suggestions that sulfate has been a minor player in sulfur cycling through the Phanerozoic Eon. PMID:23650346

  2. Progression in sulfur isotopic compositions from coal to fly ash: Examples from single-source combustion in Indiana

    USGS Publications Warehouse

    Yaofa, Jiang; Elswick, E.R.; Mastalerz, Maria

    2008-01-01

    Sulfur occurs in multiple mineral forms in coals, and its fate in coal combustion is still not well understood. The sulfur isotopic composition of coal from two coal mines in Indiana and fly ash from two power plants that use these coals were studied using geological and geochemical methods. The two coal beds are Middle Pennsylvanian in age; one seam is the low-sulfur ( 5%) Springfield Coal Member of the Petersburg Formation. Both seams have ash contents of approximately 11%. Fly-ash samples were collected at various points in the ash-collection system in the two plants. The results show notable difference in ??34S for sulfur species within and between the low-sulfur and high-sulfur coal. The ??34S values for all sulfur species are exclusively positive in the low-sulfur Danville coal, whereas the ??34S values for sulfate, pyritic, and organic sulfur are both positive and negative in the high-sulfur Springfield coal. Each coal exhibits a distinct pattern of stratigraphic variation in sulfur isotopic composition. Overall, the ??34S for sulfur species values increase up the section in the low-sulfur Danville coal, whereas they show a decrease up the vertical section in the high-sulfur Springfield coal. Based on the evolution of ??34S for sulfur species, it is suggested that there was influence of seawater on peat swamp, with two marine incursions occurring during peat accumulation of the high-sulfur Springfield coal. Therefore, bacterial sulfate reduction played a key role in converting sulfate into hydrogen sulfide, sulfide minerals, and elemental sulfur. The differences in ??34S between sulfate sulfur and pyritic sulfur is very small between individual benches of both coals, implying that some oxidation occurred during deposition or postdeposition. The ??34S values for fly ash from the high-sulfur Springfield coal (averaging 9.7???) are greatly enriched in 34S relative to those in the parent coal (averaging 2.2???). This indicates a fractionation of sulfur isotopes

  3. Large sulfur isotope fractionations associated with Neoarchean microbial sulfate reduction.

    PubMed

    Zhelezinskaia, Iadviga; Kaufman, Alan J; Farquhar, James; Cliff, John

    2014-11-01

    The minor extent of sulfur isotope fractionation preserved in many Neoarchean sedimentary successions suggests that sulfate-reducing microorganisms played an insignificant role in ancient marine environments, despite evidence that these organisms evolved much earlier. We present bulk, microdrilled, and ion probe sulfur isotope data from carbonate-associated pyrite in the ~2.5-billion-year-old Batatal Formation of Brazil, revealing large mass-dependent fractionations (approaching 50 per mil) associated with microbial sulfate reduction, as well as consistently negative Δ(33)S values (~ -2 per mil) indicative of atmospheric photochemical reactions. Persistent (33)S depletion through ~60 meters of shallow marine carbonate implies long-term stability of seawater sulfate abundance and isotope composition. In contrast, a negative Δ(33)S excursion in lower Batatal strata indicates a response time of ~40,000 to 150,000 years, suggesting Neoarchean sulfate concentrations between ~1 and 10 μM.

  4. Patterns of sulfur isotope fractionation during microbial sulfate reduction.

    PubMed

    Bradley, A S; Leavitt, W D; Schmidt, M; Knoll, A H; Girguis, P R; Johnston, D T

    2016-01-01

    Studies of microbial sulfate reduction have suggested that the magnitude of sulfur isotope fractionation varies with sulfate concentration. Small apparent sulfur isotope fractionations preserved in Archean rocks have been interpreted as suggesting Archean sulfate concentrations of <200 μm, while larger fractionations thereafter have been interpreted to require higher concentrations. In this work, we demonstrate that fractionation imposed by sulfate reduction can be a function of concentration over a millimolar range, but that nature of this relationship depends on the organism studied. Two sulfate-reducing bacteria grown in continuous culture with sulfate concentrations ranging from 0.1 to 6 mm showed markedly different relationships between sulfate concentration and isotope fractionation. Desulfovibrio vulgaris str. Hildenborough showed a large and relatively constant isotope fractionation ((34) εSO 4-H2S ≅ 25‰), while fractionation by Desulfovibrio alaskensis G20 strongly correlated with sulfate concentration over the same range. Both data sets can be modeled as Michaelis-Menten (MM)-type relationships but with very different MM constants, suggesting that the fractionations imposed by these organisms are highly dependent on strain-specific factors. These data reveal complexity in the sulfate concentration-fractionation relationship. Fractionation during MSR relates to sulfate concentration but also to strain-specific physiological parameters such as the affinity for sulfate and electron donors. Previous studies have suggested that the sulfate concentration-fractionation relationship is best described with a MM fit. We present a simple model in which the MM fit with sulfate concentration and hyperbolic fit with growth rate emerge from simple physiological assumptions. As both environmental and biological factors influence the fractionation recorded in geological samples, understanding their relationship is critical to interpreting the sulfur isotope record

  5. An integrated sulfur isotope model for Namibian shelf sediments

    NASA Astrophysics Data System (ADS)

    Dale, Andrew W.; Brüchert, Volker; Alperin, Marc; Regnier, Pierre

    2009-04-01

    In this study the sulfur cycle in the organic-rich mud belt underlying the highly productive upwelling waters of the Namibian shelf is quantified using a 1D reaction-transport model. The model calculates vertical concentration and reaction rate profiles in the top 500 cm of sediment which are compared to a comprehensive dataset which includes carbon, sulfur, nitrogen and iron compounds as well as sulfate reduction (SR) rates and stable sulfur isotopes ( 32S, 34S). The sulfur dynamics in the well-mixed surface sediments are strongly influenced by the activity of the large sulfur bacteria Thiomargaritanamibiensis which oxidize sulfide (H 2S) to sulfate ( SO42-) using sea water nitrate ( NO3-) as the terminal electron acceptor. Microbial sulfide oxidation (SOx) is highly efficient, and the model predicts intense cycling between SO42- and H 2S driven by coupled SR and SOx at rates exceeding 6.0 mol S m -2 y -1. More than 96% of the SR is supported by SOx, and only 2-3% of the SO42- pool diffuses directly into the sediment from the sea water. A fraction of the SO42- produced by Thiomargarita is drawn down deeper into the sediment where it is used to oxidize methane anaerobically, thus preventing high methane concentrations close to the sediment surface. Only a small fraction of total H 2S production is trapped as sedimentary sulfide, mainly pyrite (FeS 2) and organic sulfur (S org) (˜0.3 wt.%), with a sulfur burial efficiency which is amongst the lowest values reported for marine sediments (<1%). Yet, despite intense SR, FeS 2 and S org show an isotope composition of ˜5 ‰ at 500 cm depth. These heavy values were simulated by assuming that a fraction of the solid phase sulfur exchanges isotopes with the dissolved sulfide pool. An enrichment in H 2S of 34S towards the sediment-water interface suggests that Thiomargarita preferentially remove H 232S from the pore water. A fractionation of 20-30‰ was estimated for SOx (ɛ SOx) with the model, along with a maximum

  6. Are sulfur isotope ratios sufficient to determine the antiquity of sulfate reduction?

    PubMed

    Ashendorf, D

    1980-12-01

    Sulfur isotope fractionation values have been measured in sedimentary sulfides of varying ages, The 'Antiquity and evolutionary status of bacterial sulfate reduction...' has been inferred from these measurements by Schidlowski (1979). However, under experimental conditions, the isotope values vary widely due to inadequately controlled variables. Thus the direct extrapolation of sulfur isotope fractionation values measured in the laboratory to those measured in sedimentary rocks is unwarranted. New sulfur transforming microbes have been described and recent measurements indicate that inorganic processes affect sulfur isotope fractionation values. This information is summarized here; at present sulfur isotope fractionation values are insufficient to determine the antiquity of sulfate reduction.

  7. Sulfur contents and sulfur-isotope compositions of thiotrophic symbioses in bivalve molluscs and vestimentiferan worms

    USGS Publications Warehouse

    Vetter, R.D.; Fry, B.

    1998-01-01

    Total sulfur (S(TOT)), elemental sulfur (S??) and sulfur-isotope compositions (??34S) of marine animals were analyzed to determine whether these chemical characteristics could help distinguish animals with a sulfur-based, thiotrophic nutrition from animals whose nutrition is based on methanotrophy or on more normal consumption of phytoplankton-derived organic matter. The presence of S??was almost entirely confined to the symbiont-containing tissues of thiotrophs, but was sometimes undetectable in thiotrophic species where sulfide availability was probably low. When S??contents were subtracted, the remaining tissue-sulfur concentrations were similar for all nutritional groups. ??34S values were typically lower for thiotrophs than for other groups, although there was overlap in methanotroph and thiotroph values at some sites. Field evidence supported the existence of small to moderate (1 to 10???)34S fractionations in the uptake of sulfides and metabolism of thiosulfate. In general, a total sulfur content of >3% dry weight, the presence of elemental sulfur, and ??34S values less than + 5??? can be used to infer a thiotrophic mode of nutrition.

  8. Isotopic insights into microbial sulfur cycling in oil reservoirs

    PubMed Central

    Hubbard, Christopher G.; Cheng, Yiwei; Engelbrekston, Anna; Druhan, Jennifer L.; Li, Li; Ajo-Franklin, Jonathan B.; Coates, John D.; Conrad, Mark E.

    2014-01-01

    Microbial sulfate reduction in oil reservoirs (biosouring) is often associated with secondary oil production where seawater containing high sulfate concentrations (~28 mM) is injected into a reservoir to maintain pressure and displace oil. The sulfide generated from biosouring can cause corrosion of infrastructure, health exposure risks, and higher production costs. Isotope monitoring is a promising approach for understanding microbial sulfur cycling in reservoirs, enabling early detection of biosouring, and understanding the impact of souring. Microbial sulfate reduction is known to result in large shifts in the sulfur and oxygen isotope compositions of the residual sulfate, which can be distinguished from other processes that may be occurring in oil reservoirs, such as precipitation of sulfate and sulfide minerals. Key to the success of this method is using the appropriate isotopic fractionation factors for the conditions and processes being monitored. For a set of batch incubation experiments using a mixed microbial culture with crude oil as the electron donor, we measured a sulfur fractionation factor for sulfate reduction of −30‰. We have incorporated this result into a simplified 1D reservoir reactive transport model to highlight how isotopes can help discriminate between biotic and abiotic processes affecting sulfate and sulfide concentrations. Modeling results suggest that monitoring sulfate isotopes can provide an early indication of souring for reservoirs with reactive iron minerals that can remove the produced sulfide, especially when sulfate reduction occurs in the mixing zone between formation waters (FW) containing elevated concentrations of volatile fatty acids (VFAs) and injection water (IW) containing elevated sulfate. In addition, we examine the role of reservoir thermal, geochemical, hydrological, operational and microbiological conditions in determining microbial souring dynamics and hence the anticipated isotopic signatures. PMID:25285094

  9. The Fractionation of Sulfur Isotopes during Arc Initiation - Preliminary Data

    NASA Astrophysics Data System (ADS)

    Brandl, P. A.; Ireland, T. R.; O'Neill, H. S.

    2014-12-01

    The "Stable Isotope Sensitive High-Resolution Ion Microprobe" (SHRIMP-SI) at the ANU in Canberra provides a powerful tool for in-situ analyses of light isotopes. Recently, we developed a technique to analyze the sulfur isotope composition (δ34S) of volcanic glasses. Since no interlaboratory reference material is available for this purpose, we carried out piston cylinder experiments to create artificial glasses of known sulfur isotope composition. We used natural sulfides mixed with CaO-Al2O3-SiO2 (with PtO2 in 5 mm Pt capsule) and high-Ti Mare basalt powder (graphite capsule inside the Pt capsule). Experimental conditions were set to 1400°C, 5 kbar and 4 hours. We used these artificial glasses to survey sulfur isotope fractionation during our experimental runs and for use as standard material with calibrated δ34S. Additionally, natural standards Juan de Fuca basalt (VG-2), Makaopuhi basalt (VG-A99; Hawai'i), SEIR MORB (NMNH 113716), and one rhyolite (VG-568) were analyzed repeatedly to provide sulfur isotope data of commonly used natural glass standards. IODP expedition 351 to the Amami-Sankaku Basin adjacent to the Kyushu-Palau Ridge in June-July 2014 recovered a variety of rocks related to the history of the Izu-Bonin Mariana (IBM) Arc. Basalts of the oceanic igneous crust underlying the IBM arc give us information of the basement prior to arc initiation and volcaniclastic rocks eroded from active volcanoes of the IBM arc record its evolution from inception in the Eocene through Oligocene and Miocene. Ash layers intercalated in hemipelagic sediments record the evolution of the IBM and Ryukyu arcs during the Neogene. The aim of this study is to track changes in the oxidation state of island arc magmas and the mantle wedge during the time of arc initiation. Experimental results as well as preliminary data from IODP Exp. 351 will be presented by the time of the conference.

  10. Are sulfur isotope ratios sufficient to determine the antiquity of sulfate reduction. [implications for chemical evolution

    NASA Technical Reports Server (NTRS)

    Ashendorf, D.

    1980-01-01

    Possible limitations on the use of sulfur isotope ratios in sedimentary sulfides to infer the evolution of microbial sulfate reduction are discussed. Current knowledge of the ways in which stable sulfur isotope ratios are altered by chemical and biological processes is examined, with attention given to the marine sulfur cycle involving various microbial populations, and sulfur reduction processes, and it is noted that satisfactory explanations of sulfur isotope ratios observed in live organisms and in sediments are not yet available. It is furthermore pointed out that all members of the same genus of sulfate reducing bacteria do not always fractionate sulfur to the same extent, that the extent of sulfur fractionation by many sulfate-reducing organisms has not yet been determined, and that inorganic processes can also affect sulfur isotope fractionation values. The information currently available is thus concluded to be insufficient to determine the time of initial appearance of biological sulfate reduction.

  11. Measuring sulfur isotopes by multicollector ICP-MS

    NASA Astrophysics Data System (ADS)

    Sessions, A. L.; Adkins, J. F.

    2011-12-01

    The stable isotopes of sulfur have traditionally been measured by converting analytes to SO2, which is then introduced to a gas-source isotope ratio mass spectrometer (IRMS). Recently, we and several other groups have begun measuring S isotopes using a multicollector inductively-coupled plasma mass spectrometer (MC-ICP-MS). The approach offers several advantages, including decreased reliance on preparatory chemical conversion (including combustion) of analytes, greater flexibility of sample introduction, and increased sensitivity. Sulfur is measured as monoatomic S+ ions produced in the plasma source, and can be introduced in a variety of forms including dissolved sulfate or sulfide, or as organosulfur compounds either in solution or in the gas phase. A primary requirement for accurate measurements is resolving isobaric interferences from O2+, which requires a mass analyzer with resolution > 4000. Using a Thermo Neptune system, we document accuracy and precision for δ34S near the shot-noise limit (ie, counting statistics) for both aqueous solutions and gas streams. For samples containing 50 pmol S (as gaseous SF6), this corresponds to ~0.3%; for 50 nmol S (as aqueous SO4) this is ~0.02%. One important application of this new analytical approach is the measurement of S isotopes in volatile and semivolatile organic compounds. No IRMS-based methods for measuring compound-specific S isotopes currently exist. We have demonstrated this capability by coupling a capillary gas chromatograph (GC) directly to the ICP-MS via a heated transfer line. Isotope ratios (δ34S values) are calculated relative to co-injected peaks of SF6 reference gas, in the same manner as is used by GC-combustion-IRMS approaches. As a demonstration of this capability, we measured the δ34S values of individual thiophene isomers separated by GC from a crude oil, which range over 20% for compounds from the same oil. A second application of ICP-MS to sulfur isotopes is the measurement of dissolved

  12. Sulfur Isotope Geochemistry of the Lost City Hydrothermal Vent Fluids

    NASA Astrophysics Data System (ADS)

    Frueh-Green, G. L.; Bernasconi, S. M.; Butterfield, D. A.; Kelley, D. S.

    2004-12-01

    At the Lost City Hydrothermal Vent Field (Mid-Atlantic Ridge, 30° N), reactions between seawater and ultramafic rocks produce high alkaline (pH 9 to 11) fluids that are venting at temperatures of 40 to 90° C and result in the formation of up to 60m tall carbonate-brucite structures. The fluids are enriched in hydrogen, methane and other hydrocarbons, and support dense microbial communities. We present sulfur isotope data of dissolved sulfate and coexisting sulfide in the fluids venting at Lost City, which together with C-isotope data provide constraints on the links between chemical and biological processes associated with serpentinization. The sulfur isotope composition of sulfate increases from seawater values of +21‰ (VCDT) in fluids with sulfate concentrations of 28 mM to values of up to +30‰ in the low sulfate-, high pH end-member hydrothermal fluids. Sulfide concentrations range between 50 and 2780 micromolar. Sulfur isotope compositions of the sulfides lie in a narrow range of +34 to +37‰ (VCDT) and show no clear correlation with concentrations. The isotopic compositions of dissolved inorganic carbon vary between -0.5‰ (VPDB) in the high sulfate samples and -18‰ in the low sulfate samples. This covariance indicates active sulfate reduction in the vent structures and/or in the shallow serpentinite subsurface. Sulfate reduction likely contributes to the variability of carbon isotope compositions observed in both the dissolved inorganic carbon and the carbonate minerals forming the structures. These data, together with C- and O-isotope data of the vent structures, provide evidence that methane oxidation coupled with sulfate reduction during mixing of the more pristine, hydrogen and methane-rich hydrothermal end-member fluids with seawater is an important process in hydrothermal carbonate precipitation at Lost City. Our results are consistent with previous microbiological and organic geochemical studies, which indicate a close association of methane

  13. Sulfur isotope homogeneity of oceanic DMSP and DMS

    PubMed Central

    Amrani, Alon; Said-Ahmad, Ward; Shaked, Yeala; Kiene, Ronald P.

    2013-01-01

    Oceanic emissions of volatile dimethyl sulfide (DMS) represent the largest natural source of biogenic sulfur to the global atmosphere, where it mediates aerosol dynamics. To constrain the contribution of oceanic DMS to aerosols we established the sulfur isotope ratios (34S/32S ratio, δ34S) of DMS and its precursor, dimethylsulfoniopropionate (DMSP), in a range of marine environments. In view of the low oceanic concentrations of DMS/P, we applied a unique method for the analysis of δ34S at the picomole level in individual compounds. Surface water DMSP collected from six different ocean provinces revealed a remarkable consistency in δ34S values ranging between +18.9 and +20.3‰. Sulfur isotope composition of DMS analyzed in freshly collected seawater was similar to δ34S of DMSP, showing that the in situ fractionation between these species is small (<+1‰). Based on volatilization experiments, emission of DMS to the atmosphere results in a relatively small fractionation (−0.5 ± 0.2‰) compared with the seawater DMS pool. Because δ34S values of oceanic DMS closely reflect that of DMSP, we conclude that the homogenous δ34S of DMSP at the ocean surface represents the δ34S of DMS emitted to the atmosphere, within +1‰. The δ34S of oceanic DMS flux to the atmosphere is thus relatively constant and distinct from anthropogenic sources of atmospheric sulfate, thereby enabling estimation of the DMS contribution to aerosols. PMID:24167289

  14. Calibrated sulfur isotope abundance ratios of three IAEA sulfur isotope reference materials and V-CDT with a reassessment of the atomic weight of sulfur

    NASA Astrophysics Data System (ADS)

    Ding, T.; Valkiers, S.; Kipphardt, H.; De Bièvre, P.; Taylor, P. D. P.; Gonfiantini, R.; Krouse, R.

    2001-09-01

    Calibrated values have been obtained for sulfur isotope abundance ratios of sulfur isotope reference materials distributed by the IAEA (Vienna). For the calibration of the measurements, a set of synthetic isotope mixtures were prepared gravimetrically from high purity Ag 2S materials enriched in 32S, 33S, and 34S. All materials were converted into SF 6 gas and subsequently, their sulfur isotope ratios were measured on the SF 5+ species using a special gas source mass spectrometer equipped with a molecular flow inlet system (IRMM's Avogadro II amount comparator). Values for the 32S/ 34S abundance ratios are 22.650 4(20), 22.142 4(20), and 23.393 3(17) for IAEA-S-1, IAEA-S-2, and IAEA-S-3, respectively. The calculated 32S/ 34S abundance ratio for V-CDT is 22.643 6(20), which is very close to the calibrated ratio obtained by Ding et al. (1999). In this way, the zero point of the VCDT scale is anchored firmly to the international system of units SI. The 32S/ 33S abundance ratios are 126.942(47), 125.473(55), 129.072(32), and 126.948(47) for IAEA-S-1, IAEA-S-2, IAEA-S-3, and V-CDT, respectively. In this way, the linearity of the V-CDT scale is improved over this range. The values of the sulfur molar mass for IAEA-S-1 and V-CDT were calculated to be 32.063 877(56) and 32.063 911(56), respectively, the values with the smallest combined uncertainty ever reported for the sulfur molar masses (atomic weights).

  15. Evaluation of the sulfur isotopic composition and homogeneity of the Soufre de Lacq reference material

    USGS Publications Warehouse

    Carmody, R.W.; Seal, R.R., II

    1999-01-01

    Sulfur isotopic analysis of the elemental sulfur reference material Soufre de Lacq, prepared as silver sulfide by chromous chloride reduction and as copper sulfide by sealed-tube synthesis, indicates that Soufre de Lacq is isotopically homogeneous across different size fractions to within analytical uncertainty (??0.15???). The sulfur isotopic composition of aliquots of Soufre de Lacq prepared by these two techniques are identical to within analytical uncertainty. The mean sulfur isotopic composition for Soufre de Lacq prepared as silver sulfide and copper sulfide (relative to VCDT) is +16.20 ?? 0.15??? (1??).

  16. Sulfur and oxygen isotope insights into sulfur cycling in shallow-sea hydrothermal vents, Milos, Greece

    PubMed Central

    2014-01-01

    Shallow-sea (5 m depth) hydrothermal venting off Milos Island provides an ideal opportunity to target transitions between igneous abiogenic sulfide inputs and biogenic sulfide production during microbial sulfate reduction. Seafloor vent features include large (>1 m2) white patches containing hydrothermal minerals (elemental sulfur and orange/yellow patches of arsenic-sulfides) and cells of sulfur oxidizing and reducing microorganisms. Sulfide-sensitive film deployed in the vent and non-vent sediments captured strong geochemical spatial patterns that varied from advective to diffusive sulfide transport from the subsurface. Despite clear visual evidence for the close association of vent organisms and hydrothermalism, the sulfur and oxygen isotope composition of pore fluids did not permit delineation of a biotic signal separate from an abiotic signal. Hydrogen sulfide (H2S) in the free gas had uniform δ34S values (2.5 ± 0.28‰, n = 4) that were nearly identical to pore water H2S (2.7 ± 0.36‰, n = 21). In pore water sulfate, there were no paired increases in δ34SSO4 and δ18OSO4 as expected of microbial sulfate reduction. Instead, pore water δ34SSO4 values decreased (from approximately 21‰ to 17‰) as temperature increased (up to 97.4°C) across each hydrothermal feature. We interpret the inverse relationship between temperature and δ34SSO4 as a mixing process between oxic seawater and 34S-depleted hydrothermal inputs that are oxidized during seawater entrainment. An isotope mass balance model suggests secondary sulfate from sulfide oxidation provides at least 15% of the bulk sulfate pool. Coincident with this trend in δ34SSO4, the oxygen isotope composition of sulfate tended to be 18O-enriched in low pH (<5), high temperature (>75°C) pore waters. The shift toward high δ18OSO4 is consistent with equilibrium isotope exchange under acidic and high temperature conditions. The source of H2S contained in hydrothermal fluids could not be

  17. Sulfur and oxygen isotope insights into sulfur cycling in shallow-sea hydrothermal vents, Milos, Greece.

    PubMed

    Gilhooly, William P; Fike, David A; Druschel, Gregory K; Kafantaris, Fotios-Christos A; Price, Roy E; Amend, Jan P

    2014-01-01

    Shallow-sea (5 m depth) hydrothermal venting off Milos Island provides an ideal opportunity to target transitions between igneous abiogenic sulfide inputs and biogenic sulfide production during microbial sulfate reduction. Seafloor vent features include large (>1 m(2)) white patches containing hydrothermal minerals (elemental sulfur and orange/yellow patches of arsenic-sulfides) and cells of sulfur oxidizing and reducing microorganisms. Sulfide-sensitive film deployed in the vent and non-vent sediments captured strong geochemical spatial patterns that varied from advective to diffusive sulfide transport from the subsurface. Despite clear visual evidence for the close association of vent organisms and hydrothermalism, the sulfur and oxygen isotope composition of pore fluids did not permit delineation of a biotic signal separate from an abiotic signal. Hydrogen sulfide (H2S) in the free gas had uniform δ(34)S values (2.5 ± 0.28‰, n = 4) that were nearly identical to pore water H2S (2.7 ± 0.36‰, n = 21). In pore water sulfate, there were no paired increases in δ(34)SSO4 and δ(18)OSO4 as expected of microbial sulfate reduction. Instead, pore water δ(34)SSO4 values decreased (from approximately 21‰ to 17‰) as temperature increased (up to 97.4°C) across each hydrothermal feature. We interpret the inverse relationship between temperature and δ(34)SSO4 as a mixing process between oxic seawater and (34)S-depleted hydrothermal inputs that are oxidized during seawater entrainment. An isotope mass balance model suggests secondary sulfate from sulfide oxidation provides at least 15% of the bulk sulfate pool. Coincident with this trend in δ(34)SSO4, the oxygen isotope composition of sulfate tended to be (18)O-enriched in low pH (<5), high temperature (>75°C) pore waters. The shift toward high δ(18)OSO4 is consistent with equilibrium isotope exchange under acidic and high temperature conditions. The source of H2S contained in hydrothermal

  18. Neoproterozoic Seawater Sulfur Isotopes and the Evolution of Microbial Sulfur Species

    NASA Astrophysics Data System (ADS)

    Hurtgen, M. T.; Arthur, M. A.

    2003-12-01

    Canfield and Teske (1996) proposed that an increase in the variability of δ 34Spyrite sometime in the Neoproterozoic\\--along with a corresponding increase in the isotopic difference between sulfate and pyrite (Δ 34S)\\--resulted from a fundamental shift in the biogeochemical cycling of sulfur, facilitated by changes in the oxidation-state of the Earth's surface. They proposed that an increase in the depth of oxygenation of the surface ocean triggered the evolution of a non-photosynthetic sulfide-oxidizing bacteria and that these bacteria, in consortium with a host of microbes associated with the oxidative part of the sulfur cycle, were responsible for the increase in Δ 34S to values greater than 46 ‰ . However, Δ 34S values have been poorly constrained for the Neoproterozoic because the S isotopic composition of seawater sulfate has been largely unknown. In this study, we have reconstructed the S isotopic evolution of Neoproterozoic seawater sulfate by analyzing the isotopic composition of trace sulfate extracted from carbonates collected in South Australia, Namibia and Death Valley, CA. Our results indicate that Neoproterozoic Δ 34S values between ˜800 to 570 Ma were less than 46 ‰ and that the apparent increase in δ 34Spyrite variability during this time resulted from an ocean with low sulfate concentrations and rapidly evolving δ 34Ssulfate\\--likely a consequence of severe late Neoproterozoic glacial events. Therefore, it is difficult to argue using S isotopes that a non-photosynthetic sulfide-oxidizing bacteria evolved at this time. Furthermore, we speculate that the evolution of a non-photosynthetic sulfide-oxidizing bacteria was not necessary for disproportionation reactions to operate. Rather, we argue that intermediate S species and disproportionation reactions were likely occurring through much of the Proterozoic and that the overall low Δ 34S is simply a function of more efficient pyrite burial in an ocean with fewer oxidants and low

  19. [Comparisons of sulfur contents and isotopes between mosses and surface soils in Jiangxi Province].

    PubMed

    Li, Nan; Xiao, Hua-Yun; Chen, Yong-Zhong; Zhou, Dan; Luo, Li; Wu, Dai-She

    2013-10-01

    In order to study the influence of atmospheric sulfur on soil sulfur, the forest surface soil samples and moss samples were collected in north areas of Jiangxi province. Contents and isotopes of sulfur in different forms (total sulfur, water-soluble sulfur, absorbed sulfur and organic sulfur) were determined. The average sulfur content of mosses was 0. 34% +/- 0. 20%. All of the delta34S values except at Fengcheng (-3. 31 per thousand) were positive, the average was 5.64 per thousand +/- 2. 23 per thousand. The average contents of soil total sulfur were between 189.0 mg.kg-1 and 793.5 mg.kg-1. The organic sulfur was the main sulfur form in surface soils and the contents of water-soluble sulfur were the lowest. The delta34S values of total sulfur were in the range of 4. 45 per thousand +/-10. 28 per thousand. The highest soil delta34S values were determined for organic sulfur and the delta34S values of water-soluble and absorbed sulfur were similar. The contents of soil total sulfur were much lower than those of the mosses. Except for organic sulfur (R = 0. 50, P >0. 05) , the delta34S values of total sulfur, water-soluble sulfur and absorbed sulfur were all significantly correlated with those of moss sulfur (R >0.7, P <0. 01). These results indicated that atmospheric sulfur directly affected the total sulfur, water-soluble sulfur and absorbed sulfur, but not the organic sulfur.

  20. Multiple linear regression for isotopic measurements

    NASA Astrophysics Data System (ADS)

    Garcia Alonso, J. I.

    2012-04-01

    There are two typical applications of isotopic measurements: the detection of natural variations in isotopic systems and the detection man-made variations using enriched isotopes as indicators. For both type of measurements accurate and precise isotope ratio measurements are required. For the so-called non-traditional stable isotopes, multicollector ICP-MS instruments are usually applied. In many cases, chemical separation procedures are required before accurate isotope measurements can be performed. The off-line separation of Rb and Sr or Nd and Sm is the classical procedure employed to eliminate isobaric interferences before multicollector ICP-MS measurement of Sr and Nd isotope ratios. Also, this procedure allows matrix separation for precise and accurate Sr and Nd isotope ratios to be obtained. In our laboratory we have evaluated the separation of Rb-Sr and Nd-Sm isobars by liquid chromatography and on-line multicollector ICP-MS detection. The combination of this chromatographic procedure with multiple linear regression of the raw chromatographic data resulted in Sr and Nd isotope ratios with precisions and accuracies typical of off-line sample preparation procedures. On the other hand, methods for the labelling of individual organisms (such as a given plant, fish or animal) are required for population studies. We have developed a dual isotope labelling procedure which can be unique for a given individual, can be inherited in living organisms and it is stable. The detection of the isotopic signature is based also on multiple linear regression. The labelling of fish and its detection in otoliths by Laser Ablation ICP-MS will be discussed using trout and salmon as examples. As a conclusion, isotope measurement procedures based on multiple linear regression can be a viable alternative in multicollector ICP-MS measurements.

  1. Sulfur isotope and porewater geochemistry of Florida escarpment seep sediments

    USGS Publications Warehouse

    Chanton, J.P.; Martens, C.S.; Paull, C.K.; Coston, J.A.

    1993-01-01

    Distributions of porewater constituents, SO4=, NH4+, Cl-, ???CO2, and H2S, solid phase iron, and sulfur concentrations, and the sulfur isotopic composition of dissolved and solid phases were investigated in sediments from abyssal seeps at the base of the Florida escarpment. Despite the apparent similarity of seep sediment porewater chemistry to that of typical marine sediments undergoing early diagenesis, relationships between chemical distributions and isotopic measurements revealed that the distribution of pore fluid constituents was dominated by processes occurring within the platform rather than by in situ microbial processes. Ammonium and sulfate concentrations were linearly correlated with chloride concentrations, indicating that variations in porewater chemistry were controlled by the admixture of seawater and a sulfate depleted brine with a chlorinity of 27.5 ?? 1.9%. and 2.2 ?? 1.3 mM ammonium concentration. At sites dominated by seepage, dissolved sulfate isotopic composition remained near seawater values despite depletion in porewater concentrations. Porewater ???CO2 concentrations were found to be elevated relative to seawater, but not to the extent predicted from the observed sulfate depletion. Sediment solid phase sulfur was predominantly pyrite, at concentrations as high as 20% S by weight. In contrast to typical marine deposits, pyrite concentrations were not related to the quantity of sedimentary organic matter. Pyrite ??34S values ranged from -29%. to + 21%. (CDT). However, only positive ??34S values were observed at sites associated with high pyrite concentrations. Isotopically heavy pyrite was observed at sites with porewater sulfate of seawater-like isotopic composition. Isotopically light pyrite was associated with sites where porewater sulfate exhibited ??34S values greater than those in seawater, indicating the activity of in situ microbial sulfate reduction. Thus, dual sulfide sources are suggested to explain the range in sediment pyrite

  2. Relationship between microbial sulfate reduction rates and sulfur isotopic fractionation

    NASA Astrophysics Data System (ADS)

    Matsu'Ura, F.

    2009-12-01

    Sulfate reduction is one of the common processes to obtain energy for certain types of microorganisms.They use hydrogen gas or organic substrates as electron donor and sulfates as electron acceptor, and reduce sulfates to sulfides. Sulfate reducing microbes extend across domains Archea and Bacteria, and are believed to be one of the earliest forms of terrestrial life (Shen 2004). The origin of 34S-depleted (light) sulfide sulfur, especially δ34S < -30 ‰, around hydrothermal vents or beneath the sea-floor is speculated to be the products of sulfate reducers. But laboratory experiments using sulfate reducers fail to produce such light sulfur, and many models were proposed to explain the discrepancy. Canfield et al. (2006) proposed so-called "standard model" based on previous studies. The standard model explained the reason for the large fractionation by temperature dependence of sulfur isotopic fractionation factor and rate of sulfate reduction, which indicated the growth conditions of microbes. However, they failed to prove their model by their other experiments (Canfield et al., 2006). In this study, I performed laboratory culture experiment of sulfate reducing bacteria (SRB) to explain the 34S-depleted sulfide sulfur. [Experiments] To compare the result with Canfield et al. (2006), I used Desulfovibrio desulfuricans for my laboratory culture experiment. D. desulfuricans was inoculated into glass vials, which contain 40ml of liquid culture media slightly modified from DSMZ #63 medium.Excess amount of Fe (II) is added to the DSMZ#63 medium to precipitate sulfide as iron sulfide. The vials were incubated at 25°C, 30°C, and 37°C, respectively. 21 vials were used for one temperature and sulfide and sulfate was collected from each three glass vials at every 12 hours from 72 hours to 144 hours after start of incubation. The sulfide was precipitated as iron sulfide and the sulfate was precipitated as barite. Sulfur isotope compositions of sulfate and sulfide were

  3. Sulfur Isotopic Fractionation During Dissimilatory Sulfate Reduction from the Perspective of an Entire Microbial Metabolism

    NASA Astrophysics Data System (ADS)

    Webber, B.; Lau, L.; Wing, B.

    2009-05-01

    Whether in the investigation of the most ancient life on Earth, examination of surface oxidation properties across geological timescales, or the estimation of microbial metabolism in inaccessible environments, dissimilatory sulfate reduction (DSR) constrains biogeochemical processes in a variety of spatial and temporal scales. Pioneering work in the 1970s established the importance of DSR to biogeochemical processes and its potential as a geochemical tracer, and models for biological controls of DSR were published from empirical results of in vitro microbial cultures. Recent efforts have expanded upon this body of work and further extended toward multiple sulfur isotopes and through the more precise definition of the biological processes themselves. Resulting from these recent efforts is an rigorous description of DSR of the sulfur metabolism of sulfate-reducing bacteria. However, despite these efforts, the exact mechanisms of DSR within the scope of a complex system such as microbial metabolism remain incomplete and obscure. We will be presenting ongoing work coupling together recent mathematical models of isotopic fractionation with a flux-oriented, genomically-derived software model of the metabolism of Desulfovibrio vulgaris, a patent sulfate-reducing bacterium. Our presentation will explore the effects on isotopic fractionation throughout the sulfate reduction pathway of D. vulgaris by a multitude of separate and distinct biological pathways within the bacterial metabolism. Further, we will be discussing both the pitfalls and promise of such an approach and its implications for future research.

  4. Sulfur isotope insights into microbial sulfate reduction: When microbes meet models

    NASA Astrophysics Data System (ADS)

    Johnston, David T.; Farquhar, James; Canfield, Donald E.

    2007-08-01

    Metabolic models for fractionations produced by sulfate-reducing Bacteria and Archaea derived from experimental observations are the cornerstone of our interpretation of ancient and modern biogeochemical cycles. Although recent studies have called into question a traditionally accepted model, experimental evidence has been lacking for such a claim. We present data from all four sulfur isotopes that suggest that the internal fractionations associated with the sulfate reduction network are larger than previous estimates. Models of a traditional sulfate reduction network, as well as a more recent incarnation of the sulfate reduction network (with multiple sulfur intermediates) are constructed to aid in the understanding of new experimental data. These data also allow for the further development of additional minor isotope relationships, one of which is easily measurable in geologic settings and accurately depicts the net effect of an environment, whereas the other is more applicable to modern environments and may better illuminate the specific process(es) controlling the fractionation in those environments. This approach illustrates the uses of systems containing more than two isotopes.

  5. Influence of Purple Sulfur Bacteria on the biogeochemistry of Carbon and Sulfur Isotopes in Crystal Lake, OH

    NASA Astrophysics Data System (ADS)

    Meyer, A.; Nichols, D. L.; Cheng, S.

    2013-12-01

    Crystal Lakes are a series of four interconnected mesotrophic, moulin-induced glacial lakes in west-central Ohio. The study site, Main Lake (a.k.a. Crystal Lake), is the largest and deepest lake among them. It is about 5 ha with a maximum depth of 11.9 meters and a mean depth of 3.8 meters. Thermal stratification develops during the warmer months. Photosynthesis, which preferentially uptakes lighter isotopes, is the primary pathway for carbon and sulfur isotope fractionation in natural waters. Photosynthesizers present at Crystal Lake include green algae, diatoms, cyanobacteria, and purple sulfur bacteria (PSB). Phytoplankton growth is limited by nutrient availability, influencing the extent of fractionation. Purple sulfur bacteria (PSB) utilize sulfide as an electron donor instead of water. The layer of concentrated PSB population exists between oxic and anoxic water in lakes where sufficient light and sulfide are present. These bacteria impact the levels of several sulfur compounds and isotopic composition within lake systems by oxidizing sulfide to sulfate. Field parameters collected in warmer months show turbidity and chlorophyll peaks around 6 m with variations caused by temperature, light, and nutrient availability. The dissolved oxygen minimum and the redox and sulfate maxima generally correspond with the turbidity and chlorophyll peaks, indicating the presence of a PSB layer. This layer occurs at the boundary between the metalimnion and hypolimnion. Sulfide concentrations increased from a maximum of 0.02 mg/L in May to a maximum of 9.25 mg/L in August. In May sulfide was only found at 10.4 m and below while in August it was present at 6 m and below. Sulfate values remain relatively constant with a maximum at the layer of PSB, then decline with depth where Sulfide is abundant. δ13C-DIC values peak at 6 m corresponding with the layer of PSB. This peak may be due to the influence of PSB on carbon isotope fractionation. The carbon isotope composition of

  6. Using stable isotopes to monitor forms of sulfur during desulfurization processes: A quick screening method

    USGS Publications Warehouse

    Liu, Chao-Li; Hackley, Keith C.; Coleman, D.D.; Kruse, C.W.

    1987-01-01

    A method using stable isotope ratio analysis to monitor the reactivity of sulfur forms in coal during thermal and chemical desulfurization processes has been developed at the Illinois State Geological Survey. The method is based upon the fact that a significant difference exists in some coals between the 34S/32S ratios of the pyritic and organic sulfur. A screening method for determining the suitability of coal samples for use in isotope ratio analysis is described. Making these special coals available from coal sample programs would assist research groups in sorting out the complex sulfur chemistry which accompanies thermal and chemical processing of high sulfur coals. ?? 1987.

  7. Concentration and isotopic composition of carbon and sulfur in apollo 11 lunar samples.

    PubMed

    Kaplan, I R; Smith, J W

    1970-01-30

    The concentration of carbon and sulfur in six samples ranged between 20 to 200 and 650 to 2300 parts per million, respectively. Carbon was present in gaseous, volatilizable, and nonvolatile forms, and terrestrial contaminants were recognized. Sulfur appeared to exist only as acid-volatile sulfide. The bulk fines contain a high concentration of carbon and a low concentration of sulfur. They are always enriched in the heavier isotope carbon-13 or sulfur-34. The fine-grained basaltic rocks show the reverse relation; lowest carbon, highest sulfide concentrations, and no apparent enrichment in heavy isotopes. The breccias are of intermediate composition.

  8. Influence of sulfate reduction rates on the Phanerozoic sulfur isotope record

    NASA Astrophysics Data System (ADS)

    Leavitt, William D.; Halevy, Itay; Bradley, Alexander S.; Johnston, David T.

    2013-07-01

    Phanerozoic levels of atmospheric oxygen relate to the burial histories of organic carbon and pyrite sulfur. The sulfur cycle remains poorly constrained, however, leading to concomitant uncertainties in O2 budgets. Here we present experiments linking the magnitude of fractionations of the multiple sulfur isotopes to the rate of microbial sulfate reduction. The data demonstrate that such fractionations are controlled by the availability of electron donor (organic matter), rather than by the concentration of electron acceptor (sulfate), an environmental constraint that varies among sedimentary burial environments. By coupling these results with a sediment biogeochemical model of pyrite burial, we find a strong relationship between observed sulfur isotope fractionations over the last 200 Ma and the areal extent of shallow seafloor environments. We interpret this as a global dependency of the rate of microbial sulfate reduction on the availability of organic-rich sea-floor settings. However, fractionation during the early/mid-Paleozoic fails to correlate with shelf area. We suggest that this decoupling reflects a shallower paleoredox boundary, primarily confined to the water column in the early Phanerozoic. The transition between these two states begins during the Carboniferous and concludes approximately around the Triassic-Jurassic boundary, indicating a prolonged response to a Carboniferous rise in O2. Together, these results lay the foundation for decoupling changes in sulfate reduction rates from the global average record of pyrite burial, highlighting how the local nature of sedimentary processes affects global records. This distinction greatly refines our understanding of the S cycle and its relationship to the history of atmospheric oxygen.

  9. Influence of sulfate reduction rates on the Phanerozoic sulfur isotope record.

    PubMed

    Leavitt, William D; Halevy, Itay; Bradley, Alexander S; Johnston, David T

    2013-07-01

    Phanerozoic levels of atmospheric oxygen relate to the burial histories of organic carbon and pyrite sulfur. The sulfur cycle remains poorly constrained, however, leading to concomitant uncertainties in O2 budgets. Here we present experiments linking the magnitude of fractionations of the multiple sulfur isotopes to the rate of microbial sulfate reduction. The data demonstrate that such fractionations are controlled by the availability of electron donor (organic matter), rather than by the concentration of electron acceptor (sulfate), an environmental constraint that varies among sedimentary burial environments. By coupling these results with a sediment biogeochemical model of pyrite burial, we find a strong relationship between observed sulfur isotope fractionations over the last 200 Ma and the areal extent of shallow seafloor environments. We interpret this as a global dependency of the rate of microbial sulfate reduction on the availability of organic-rich sea-floor settings. However, fractionation during the early/mid-Paleozoic fails to correlate with shelf area. We suggest that this decoupling reflects a shallower paleoredox boundary, primarily confined to the water column in the early Phanerozoic. The transition between these two states begins during the Carboniferous and concludes approximately around the Triassic-Jurassic boundary, indicating a prolonged response to a Carboniferous rise in O2. Together, these results lay the foundation for decoupling changes in sulfate reduction rates from the global average record of pyrite burial, highlighting how the local nature of sedimentary processes affects global records. This distinction greatly refines our understanding of the S cycle and its relationship to the history of atmospheric oxygen.

  10. Influence of sulfate reduction rates on the Phanerozoic sulfur isotope record

    PubMed Central

    Leavitt, William D.; Halevy, Itay; Bradley, Alexander S.; Johnston, David T.

    2013-01-01

    Phanerozoic levels of atmospheric oxygen relate to the burial histories of organic carbon and pyrite sulfur. The sulfur cycle remains poorly constrained, however, leading to concomitant uncertainties in O2 budgets. Here we present experiments linking the magnitude of fractionations of the multiple sulfur isotopes to the rate of microbial sulfate reduction. The data demonstrate that such fractionations are controlled by the availability of electron donor (organic matter), rather than by the concentration of electron acceptor (sulfate), an environmental constraint that varies among sedimentary burial environments. By coupling these results with a sediment biogeochemical model of pyrite burial, we find a strong relationship between observed sulfur isotope fractionations over the last 200 Ma and the areal extent of shallow seafloor environments. We interpret this as a global dependency of the rate of microbial sulfate reduction on the availability of organic-rich sea-floor settings. However, fractionation during the early/mid-Paleozoic fails to correlate with shelf area. We suggest that this decoupling reflects a shallower paleoredox boundary, primarily confined to the water column in the early Phanerozoic. The transition between these two states begins during the Carboniferous and concludes approximately around the Triassic–Jurassic boundary, indicating a prolonged response to a Carboniferous rise in O2. Together, these results lay the foundation for decoupling changes in sulfate reduction rates from the global average record of pyrite burial, highlighting how the local nature of sedimentary processes affects global records. This distinction greatly refines our understanding of the S cycle and its relationship to the history of atmospheric oxygen. PMID:23733944

  11. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1977-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  12. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

    1987-04-07

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

  13. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1987-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  14. Sulfur isotopic characteristics of volcanic products from the September 2014 Mount Ontake eruption, Japan

    NASA Astrophysics Data System (ADS)

    Ikehata, Kei; Maruoka, Teruyuki

    2016-07-01

    Components and sulfur isotopic compositions of pyroclastic materials from the 2014 Mt. Ontake eruption were investigated. The volcanic ash samples were found to be composed of altered volcanic fragments, alunite, anhydrite, biotite, cristobalite, gypsum, ilmenite, kaolin minerals, native sulfur, orthopyroxene, plagioclase, potassium feldspar, pyrite, pyrophyllite, quartz, rutile, and smectite, and most of these minerals were likely derived from the acidic alteration zones of Mt. Ontake. The absence of juvenile material in the eruptive products indicates that the eruption was phreatic. The sulfur isotopic compositions of the water-leached sulfate, hydrochloric acid-leached sulfate, acetone-leached native sulfur, and pyrite of the samples indicate that these sulfur species were produced by disproportionation of magmatic SO2 in the hydrothermal system at temperatures of 270-281 °C. This temperature range is consistent with that inferred from the hydrothermal mineral assemblage (e.g., pyrophyllite and rutile) in the 2014 pyroclastic materials (200-300 °C). Except for the sulfur isotopic compositions of anhydrite, which may have been altered by incorporation of sulfate minerals in a fumarolic area with lower sulfur isotopic values into the underground materials during the 1979 eruption, no significant differences in the mineral assemblages and sulfur isotopic compositions of the pyroclastic materials were identified between the products of the 2014 and 1979 Ontake phreatic eruptions, which suggests geochemical similarities in the underlying hydrothermal systems before the 2014 and 1979 eruptions.

  15. Sulfur cycling in contaminated aquifers: What can we learn from oxygen isotopes in sulfate? (Invited)

    NASA Astrophysics Data System (ADS)

    Knoeller, K.; Vogt, C.; Hoth, N.

    2009-12-01

    Bacterial reduction of dissolved sulfate (BSR) is a key process determining the natural attenuation in many contaminated aquifers. For example, in groundwater bodies affected by acid mine drainage (AMD) BSR reduces the contaminant load by producing alkalinity and facilitating a sustainable fixation of sulfur in the sediment. In aquifers contaminated with petroleum hydrocarbons sulfate may act as a terminal electron acceptor for the anaerobic oxidation of the organic contaminants to carbon dioxide and water. Due to the isotope selectivity of sulfate reducing bacteria, BSR shows the most pronounced isotope fractionation within the sulfur cycle. While sulfur displays a straightforward kinetic enrichment in the residual sulfate described by the enrichment factor epsilon (ɛ), the mechanism of oxygen isotope fractionation is still being discussed controversially. Nevertheless, it is agreed on that oxygen isotope exchange between ambient water and residual sulfate occurs during BSR in natural environments. With respect to this potential isotope exchange, the fractionation parameter theta (θ) is introduced instead of the kinetic enrichment factor epsilon (ɛ). The dual isotope system considering both sulfate-sulfur and sulfate-oxygen isotope fractionation and the respective fractionation parameters ɛ and θ provides an excellent tool for the recognition and quantification of BSR. Beyond that, the dual isotope approach may help identify and estimate interfering sulfur transformations such as re-oxidation and disproportionation processes which is especially vital for the understanding of the overall natural attenuation potential of the investigated aquifers. We present two examples from different field studies showing the benefits of applying the combination of sulfur and oxygen isotopes in dissolved sulfate to reveal the details of the sulfur cycle. The first case study is concerned with the evaluation of the potential for BSR in an AMD-affected aquifer close to an

  16. A sulfur isotope perspective of fluid transport across subduction zones

    NASA Astrophysics Data System (ADS)

    Shimizu, N.; Mandeville, C. W.

    2011-12-01

    While there is a broad consensus that mantle melting in subduction zones occurs as a result of transport of aqueous fluid (or H2O-rich components) from the subducting slab to the mantle wedge, how and where the transport occurs is still one of the outstanding questions. We report recent SIMS-based sulfur isotope data of input to (pyrites in eclogites) and output from (un-degassed olivine-hosted primitive melt inclusions from arcs) subduction zones, and argue, on the basis of sulfur isotope mass balance, that our results do not support a widely held view of deep fluid transfer from slab to wedge. We suggest, instead, that hydration of the mantle wedge occurs at shallow levels with subsequent subduction and dehydration as the likely source of H2O-rich components for magma generation. Our data from olivine-hosted un-degassed primitive melt inclusions from Galunggung (δ34S ranging from -3 to +10 %, average = +2.9% with 1000 - 2000 ppm S), Krakatau (+1.6 - +8.7 %, av = +4.2%, 1200 - 2400 ppm S), and Augustine (+11 - +17%, 2500 - 5200 ppm S) clearly show that mantle wedge (δ34S ~0%, ~250 ppm S) has been significantly modified by slab-derived fluid (e.g., seawater with +21%, ~900 ppm S). On the other hand, eclogitic pyrites from the Western Gneiss Region, Norway (2 - 2.5 GPa, 700 - 850°C: Kylander-Clark et al., 2007) range in δ34S from -3.4 to +2.8%, similar to that for altered oceanic crust (e.g., Alt, 1995). Fluid in equilibrium with the eclogitic pyrites could have δ34S up to +10% (Ohmoto and Rye, 1979) and could contain up to ~1000 ppm S, based on the solubility data of Newton and Manning (2005). Mass balance calculations show that more than 10 wt.% of this fluid would be needed for modifying δ34S of the mantle wedge with ~250 ppm S from 0% to +5%, at least an order of magnitude greater than predicted by trace element-based arguments. For fluids with more seawater-like salinity, much more would be necessary for modifying the sulfur isotopic composition of the

  17. Sulfur isotope profiles in the pelagic Panthalassic deep sea during the Permian-Triassic transition

    NASA Astrophysics Data System (ADS)

    Takahashi, Satoshi; Kaiho, Kunio; Hori, Rie S.; Gorjan, Paul; Watanabe, Takahiro; Yamakita, Satoshi; Aita, Yoshiaki; Takemura, Atsushi; Spörli, K. Bernhard; Kakegawa, Takeshi; Oba, Masahiro

    2013-06-01

    Mesozoic accretionary complexes in Japan and New Zealand contain Panthalassic low latitude and southern mid-latitude deep-water sedimentary rock respectively. These sedimentary rocks record environmental changes in the pelagic Panthalassic Ocean during the transition associated with the severe Permian-Triassic mass extinction. This study presents sulfur isotope records of sulfide from continuous deep-sea Permian-Triassic boundary sections located in northeast Japan (the Akkamori section-2, the most continuous section among other previously reported deep-sea sections) and North Island of New Zealand (the Waiheke-1 section, providing the first sulfur isotopic record from a southern hemisphere deep-sea section). Both sections show sharp ~ 15‰ drops of the sulfur isotope ratio coupled with a negative shift of organic carbon isotope ratio. Similar decreases in sulfur isotope ratio of carbonate-associated sulfates by ~ 10‰ accompanied with a negative shift of inorganic carbon isotope ratio at the end-Permian mass extinction horizon have been reported in some shallow water Paleotethyan sections. These sulfur isotope changes suggest that a massive release of 32S-enriched sulfur from the H2S-rich water to the oxic surface-waters coincided with the end-Permian mass extinction.

  18. Intracellular metabolite levels shape sulfur isotope fractionation during microbial sulfate respiration

    NASA Astrophysics Data System (ADS)

    Wing, Boswell A.; Halevy, Itay

    2014-12-01

    We present a quantitative model for sulfur isotope fractionation accompanying bacterial and archaeal dissimilatory sulfate respiration. By incorporating independently available biochemical data, the model can reproduce a large number of recent experimental fractionation measurements with only three free parameters: (i) the sulfur isotope selectivity of sulfate uptake into the cytoplasm, (ii) the ratio of reduced to oxidized electron carriers supporting the respiration pathway, and (iii) the ratio of in vitro to in vivo levels of respiratory enzyme activity. Fractionation is influenced by all steps in the dissimilatory pathway, which means that environmental sulfate and sulfide levels control sulfur isotope fractionation through the proximate influence of intracellular metabolites. Although sulfur isotope fractionation is a phenotypic trait that appears to be strain specific, we show that it converges on near-thermodynamic behavior, even at micromolar sulfate levels, as long as intracellular sulfate reduction rates are low enough (<<1 fmol H2Sṡcell-1ṡd-1).

  19. Intracellular metabolite levels shape sulfur isotope fractionation during microbial sulfate respiration

    PubMed Central

    Wing, Boswell A.; Halevy, Itay

    2014-01-01

    We present a quantitative model for sulfur isotope fractionation accompanying bacterial and archaeal dissimilatory sulfate respiration. By incorporating independently available biochemical data, the model can reproduce a large number of recent experimental fractionation measurements with only three free parameters: (i) the sulfur isotope selectivity of sulfate uptake into the cytoplasm, (ii) the ratio of reduced to oxidized electron carriers supporting the respiration pathway, and (iii) the ratio of in vitro to in vivo levels of respiratory enzyme activity. Fractionation is influenced by all steps in the dissimilatory pathway, which means that environmental sulfate and sulfide levels control sulfur isotope fractionation through the proximate influence of intracellular metabolites. Although sulfur isotope fractionation is a phenotypic trait that appears to be strain specific, we show that it converges on near-thermodynamic behavior, even at micromolar sulfate levels, as long as intracellular sulfate reduction rates are low enough (<<1 fmol H2S⋅cell−1⋅d−1). PMID:25362045

  20. Identifying the change in atmospheric sulfur sources in China using isotopic ratios in mosses

    NASA Astrophysics Data System (ADS)

    Xiao, Hua-Yun; Tang, Cong-Guo; Xiao, Hong-Wei; Liu, Xue-Yan; Liu, Cong-Qiang

    2009-08-01

    A considerable number of studies on rainwater sulfur isotopic ratios (δ34Srain) have been conducted to trace sulfur sources at a large number of sites in the past. If longitudinal studies on the isotope composition of precipitation sulfate were conducted, it is possible to relate that to changes in sulfur emissions. But direct measurement needs considerable labor and time. So, in this study, sulfur isotopic ratios in rainwater and mosses were analyzed at Guiyang and Nanchang to evaluate the possibility of using mosses as a substitute for rainwater. We found that present moss sulfur isotopic ratios were comparable to those of present rainwater. Additionally, we investigated the changes of atmospheric sulfur sources and sulfur concentrations using an isotopic graphic analysis at five industrial cities, two forested areas, and two remote areas in China. Mosses in industrial cities show a wide range of δ34S values, with the highest occurring at Chongqing (+3.9‰) and the lowest at Guiyang (-3.1‰). But as compared to those in forested and remote areas, δ34S values of mosses in all the five industrial cities are lower. On the basis of isotopic comparisons between past rainwater (reported in the literature) and present mosses, in the plot of δ34Smoss versus δ34Srain, six zones indicating different atmospheric sulfur change are separated by the 1:1 line and δ34S values of potential sulfur sources. Our results indicate that atmospheric sulfur pollution in most of the industrial cities decreased, while at the two forested areas, no significant changes were observed, and a new anxiousness coming from new energy sources (e.g., oil) appeared in some cities. Studies on the change of ambient SO2 concentrations support these results.

  1. Sulfur isotope budget (32S, 33S, 34S and 36S) in Pacific-Antarctic ridge basalts: A record of mantle source heterogeneity and hydrothermal sulfide assimilation

    NASA Astrophysics Data System (ADS)

    Labidi, J.; Cartigny, P.; Hamelin, C.; Moreira, M.; Dosso, L.

    2014-05-01

    To better address how Mid-Ocean Ridge Basalt (MORB) sulfur isotope composition can be modified by assimilation and/or by immiscible sulfide fractionation, we report sulfur (S), chlorine (Cl) and copper (Cu) abundances together with multiple sulfur isotope composition for 38 fresh basaltic glasses collected on the Pacific-Antarctic ridge. All the studied glasses - with the exception of 8 off-axis samples - exhibit relatively high Cl/K, as the result of pervasive Cl-rich fluid assimilation. This sample set hence offers an opportunity to document both the upper mantle S isotope composition and the effect of hydrothermal fluids assimilation on the S isotope composition of erupted basalts along segments that are devoid of plume influence.

  2. The 16S rDNA Phylogenetic Composition of Bacteria Implicated in Sulfur Redox Cycles and Associated Sulfur Isotope Fractionation

    NASA Astrophysics Data System (ADS)

    Bicknell, B. T.; Batts, J. E.; Krouse, H. R.

    2006-12-01

    The reduction of sulfate ion to sulfide species by sulfate reducing bacteria (SRB) is accompanied by sulfur isotope fractionation, measured in terms of changes in the δ^{34}S values for sulfate and sulfide ions relative to a defined standard. In open environments, the S-isotope compositions of sulfate and sulfide can be affected by loss from the system of sulfide species as gaseous H2S, insoluble metal sulfides such as FeS2, organic complexes or by re-oxidation. The S-isotope fractionation accompanying bacterial sulfate reduction in nature is often much larger than the maxima obtained in chemical and bacterial sulfate reduction experiments in the laboratory. One mechanism postulated for the large natural S-isotope selectivity depends on repetitive reduction-oxidation cycles. In turn, this would require a level of tolerance to oxygen by SRB in the sedimentary environment, contrary to laboratory experience with SRB strains. Bird Lake (The Coorong, South Australia) is a small calcareous, evaporative lake, where average Δ^{34}S (δ^{34}Ssulfate - δ^{34}Ssulfide) values for groundwater at 16 of the 27 sites sampled periodically since 1974, vary from 15.0 ‰ to 62.3 ‰ within the range -1.8 ‰ to 70.6 ‰. Wide fluctuations in δ34Ssulfide values at individual sites are the significant factor affecting the variability of Δ^{34}S values. Values for δ18Osulfate are elevated over that of the sulfate source to an unusual extent, reflecting re-oxidation of sulfur species and O- isotope exchange between some of these species and water. One aspect of investigations at Bird Lake was the evaluation of bacterial populations in subsurface sediments and their role in sulfur cycling. To achieve this, microcosms were established with subsurface sediment and incubated under a nitrogen atmosphere, for up to 119 days. These were sampled at various times to determine sulfur species concentrations and sulfur isotope fractionation and to generate 16S rDNA clone libraries. Results

  3. Advances in the measurement of sulfur isotopes using laser ablation MC-ICP- MS

    NASA Astrophysics Data System (ADS)

    Ridley, W. I.; Pribil, M. J.; Koenig, A. E.; Fayek, M.; Slack, J. F.

    2008-05-01

    Although sulfur is poorly ionized in an argon plasma, there are many applications for sulfur isotope analysis using an ICP source. Studies using a desolvation system (DSN) and an aqueous source of sulfur, where the sulfur is complexed with a cation to form a sulfur salt, e.g., calcium or sodium to provide a stable delivery of sulfur through the sample introduction system indicate that precision (~ 0.3 per mil) and accuracy are maintained at sulfur concentrations as low as 1 mg/L. Based on this data, solid sampling of sulfides and sulfates can provide an adequate amount supply of sulfur to an ICP source, even allowing for the relatively poor transport efficiency of laser ablation systems. The main limitations on accuracy and precision are the initial sampling volume, principally a function of spot size and laser fluence and the decreased instrument sensitivity resulting from the pseudo- medium or high resolution mode of analysis required to eliminate polyatomic isobaric interferences. These factors, in turn, determine the minimal grain size necessary for analysis. There are also fit-for-purpose considerations. For instance, many base metal sulfide systems have large variations in sulfur isotope composition, so that precision as poor as one per mil can still provide useful information. Here, we describe the methodology used at the USGS for laser ablation analysis of sulfides and sulfates using a second generation MC-ICP-MS and demonstrate the accuracy of the method based upon a grain-by-grain comparison of laser ablation and ion microprobe sulfur isotope data. A laser ablation MC-ICP-MS study of base metal mineralization at Dry Creek deposit, east-central Alaska demonstrates that the range in sulfur isotope composition of pyrite, sphalerite and galena, based on analysis of individual grains, is almost twice that reported for any other individual VMS deposit. Analysis on the microscopic scale thus provides additional insights into the potential sources of sulfur for

  4. Quadruple sulfur isotope constraints on the origin and cycling of volatile organic sulfur compounds in a stratified sulfidic lake

    NASA Astrophysics Data System (ADS)

    Oduro, Harry; Kamyshny, Alexey; Zerkle, Aubrey L.; Li, Yue; Farquhar, James

    2013-11-01

    We have quantified the major forms of volatile organic sulfur compounds (VOSCs) distributed in the water column of stratified freshwater Fayetteville Green Lake (FGL), to evaluate the biogeochemical pathways involved in their production. The lake's anoxic deep waters contain high concentrations of sulfate (12-16 mmol L-1) and sulfide (0.12 μmol L-1 to 1.5 mmol L-1) with relatively low VOSC concentrations, ranging from 0.1 nmol L-1 to 2.8 μmol L-1. Sulfur isotope measurements of combined volatile organic sulfur compounds demonstrate that VOSC species are formed primarily from reduced sulfur (H2S/HS-) and zero-valent sulfur (ZVS), with little input from sulfate. Thedata support a role of a combination of biological and abiotic processes in formation of carbon-sulfur bonds between reactive sulfur species and methyl groups of lignin components. These processes are responsible for very fast turnover of VOSC species, maintaining their low levels in FGL. No dimethylsulfoniopropionate (DMSP) was detected by Electrospray Ionization Mass Spectrometry (ESI-MS) in the lake water column or in planktonic extracts. These observations indicate a pathway distinct from oceanic and coastal marine environments, where dimethylsulfide (DMS) and other VOSC species are principally produced via the breakdown of DMSP by plankton species.

  5. Pathways for Neoarchean pyrite formation constrained by mass-independent sulfur isotopes

    PubMed Central

    Farquhar, James; Cliff, John; Zerkle, Aubrey L.; Kamyshny, Alexey; Poulton, Simon W.; Claire, Mark; Adams, David; Harms, Brian

    2013-01-01

    It is generally thought that the sulfate reduction metabolism is ancient and would have been established well before the Neoarchean. It is puzzling, therefore, that the sulfur isotope record of the Neoarchean is characterized by a signal of atmospheric mass-independent chemistry rather than a strong overprint by sulfate reducers. Here, we present a study of the four sulfur isotopes obtained using secondary ion MS that seeks to reconcile a number of features seen in the Neoarchean sulfur isotope record. We suggest that Neoarchean ocean basins had two coexisting, significantly sized sulfur pools and that the pathways forming pyrite precursors played an important role in establishing how the isotopic characteristics of each of these pools was transferred to the sedimentary rock record. One of these pools is suggested to be a soluble (sulfate) pool, and the other pool (atmospherically derived elemental sulfur) is suggested to be largely insoluble and unreactive until it reacts with hydrogen sulfide. We suggest that the relative contributions of these pools to the formation of pyrite depend on both the accumulation of the insoluble pool and the rate of sulfide production in the pyrite-forming environments. We also suggest that the existence of a significant nonsulfate pool of reactive sulfur has masked isotopic evidence for the widespread activity of sulfate reducers in the rock record. PMID:23407162

  6. Sulfur isotopic composition of surface snow along a latitudinal transect in East Antarctica

    NASA Astrophysics Data System (ADS)

    Uemura, Ryu; Masaka, Kosuke; Fukui, Kotaro; Iizuka, Yoshinori; Hirabayashi, Motohiro; Motoyama, Hideaki

    2016-06-01

    The sulfur stable isotopic values (δ34S) of sulfate aerosols can be used to assess oxidation pathways and contributions from various sources, such as marine biogenic sulfur, volcanoes, and sea salt. However, because of a lack of observations, the spatial distribution of δ34S values in Antarctic sulfate aerosols remains unclear. Here we present the first sulfur isotopic values from surface snow samples along a latitudinal transect in eastern Dronning Maud Land, East Antarctica. The δ34S values of sulfate showed remarkably uniform values, in the range of 14.8-16.9‰, and no significant decrease toward the inland part of the transect was noted. These results suggest that net isotopic fractionation during long-range transport is insignificant. Thus, the δ34S values can be used to infer source contributions. The δ34S values suggest that marine biogenic sulfur is the dominant source of sulfate aerosols, with a fractional contribution of 84 ± 16%.

  7. Chemical and sulfur isotopic composition of precipitation in Beijing, China.

    PubMed

    Zhu, Guangxu; Guo, Qingjun; Chen, Tongbin; Lang, Yunchao; Peters, Marc; Tian, Liyan; Zhang, Hanzhi; Wang, Chunyu

    2016-03-01

    China is experiencing serious acid rain contamination, with Beijing among the worst-hit areas. To understand the chemical feature and the origin of inorganic ions in precipitation of Beijing, 128 precipitation samples were collected and analyzed for major water-soluble ions and δ(34)S. The pH values ranged from 3.68 to 7.81 and showed a volume weighted average value (VWA) of 5.02, with a frequency of acid rain of 26.8 %. The VWA value of electrical conductivity (EC) was 68.6 μS/cm, which was nearly 4 times higher than the background value of northern China. Ca(2+) represented the main cation; SO4 (2-) and NO3 (-) were the dominant anion in precipitation. Our study showed that SO4 (2-) and NO3 (-) originated from coal and fossil fuel combustion; Ca(2+), Mg(2+), and K(+) were from the continental sources. The δ(34)S value of SO4 (2-) in precipitation ranged from +2.1 to +12.8‰ with an average value of +4.7‰. The δ(34)S value showed a winter maximum and a summer minimum tendency, which was mainly associated with temperature-dependent isotope equilibrium fractionation as well as combustion of coal with relatively positive δ(34)S values in winter. Moreover, the δ(34)S values revealed that atmospheric sulfur in Beijing are mainly correlated to coal burning and traffic emission; coal combustion constituted a significant fraction of the SO4 (2-) in winter precipitation. PMID:26573310

  8. Chemical and sulfur isotopic composition of precipitation in Beijing, China.

    PubMed

    Zhu, Guangxu; Guo, Qingjun; Chen, Tongbin; Lang, Yunchao; Peters, Marc; Tian, Liyan; Zhang, Hanzhi; Wang, Chunyu

    2016-03-01

    China is experiencing serious acid rain contamination, with Beijing among the worst-hit areas. To understand the chemical feature and the origin of inorganic ions in precipitation of Beijing, 128 precipitation samples were collected and analyzed for major water-soluble ions and δ(34)S. The pH values ranged from 3.68 to 7.81 and showed a volume weighted average value (VWA) of 5.02, with a frequency of acid rain of 26.8 %. The VWA value of electrical conductivity (EC) was 68.6 μS/cm, which was nearly 4 times higher than the background value of northern China. Ca(2+) represented the main cation; SO4 (2-) and NO3 (-) were the dominant anion in precipitation. Our study showed that SO4 (2-) and NO3 (-) originated from coal and fossil fuel combustion; Ca(2+), Mg(2+), and K(+) were from the continental sources. The δ(34)S value of SO4 (2-) in precipitation ranged from +2.1 to +12.8‰ with an average value of +4.7‰. The δ(34)S value showed a winter maximum and a summer minimum tendency, which was mainly associated with temperature-dependent isotope equilibrium fractionation as well as combustion of coal with relatively positive δ(34)S values in winter. Moreover, the δ(34)S values revealed that atmospheric sulfur in Beijing are mainly correlated to coal burning and traffic emission; coal combustion constituted a significant fraction of the SO4 (2-) in winter precipitation.

  9. Sulfur isotope effects associated with oxidation of sulfide by O2 in aqueous solution

    NASA Technical Reports Server (NTRS)

    Fry, B.; Ruf, W.; Gest, H.; Hayes, J. M.

    1988-01-01

    Normal sulfur isotope effects averaging epsilon = -5.2 +/- 1.4% (s.d.) were consistently observed for the oxidation of sulfide in aqueous solution. Reaction products were sulfate, thiosulfate and sulfite at pH 10.8-11 in distilled water; S0 was formed in two experiments with synthetic seawater at pH 8-9.5. Because the -5.2% normal isotope effect differs significantly from the previously measured +2% inverse effect associated with anaerobic oxidation of sulfide by photosynthetic bacteria, stable sulfur isotopic measurements are potentially useful for distinguishing aerobic vs. anaerobic sulfide oxidation in marine and freshwater sulfureta.

  10. Sulfur Isotope Fractionation during the Evolutionary Adaptation of a Sulfate-Reducing Bacterium

    PubMed Central

    Anderson-Trocmé, Luke; Whyte, Lyle G.; Zane, Grant M.; Wall, Judy D.; Wing, Boswell A.

    2015-01-01

    Dissimilatory sulfate reduction is a microbial catabolic pathway that preferentially processes less massive sulfur isotopes relative to their heavier counterparts. This sulfur isotope fractionation is recorded in ancient sedimentary rocks and generally is considered to reflect a phenotypic response to environmental variations rather than to evolutionary adaptation. Modern sulfate-reducing microorganisms isolated from similar environments can exhibit a wide range of sulfur isotope fractionations, suggesting that adaptive processes influence the sulfur isotope phenotype. To date, the relationship between evolutionary adaptation and isotopic phenotypes has not been explored. We addressed this by studying the covariation of fitness, sulfur isotope fractionation, and growth characteristics in Desulfovibrio vulgaris Hildenborough in a microbial evolution experiment. After 560 generations, the mean fitness of the evolved lineages relative to the starting isogenic population had increased by ∼17%. After 927 generations, the mean fitness relative to the initial ancestral population had increased by ∼20%. Growth rate in exponential phase increased during the course of the experiment, suggesting that this was a primary influence behind the fitness increases. Consistent changes were observed within different selection intervals between fractionation and fitness. Fitness changes were associated with changes in exponential growth rate but changes in fractionation were not. Instead, they appeared to be a response to changes in the parameters that govern growth rate: yield and cell-specific sulfate respiration rate. We hypothesize that cell-specific sulfate respiration rate, in particular, provides a bridge that allows physiological controls on fractionation to cross over to the adaptive realm. PMID:25662968

  11. Sulfur isotope fractionation during the evolutionary adaptation of a sulfate-reducing bacterium.

    PubMed

    Pellerin, André; Anderson-Trocmé, Luke; Whyte, Lyle G; Zane, Grant M; Wall, Judy D; Wing, Boswell A

    2015-04-01

    Dissimilatory sulfate reduction is a microbial catabolic pathway that preferentially processes less massive sulfur isotopes relative to their heavier counterparts. This sulfur isotope fractionation is recorded in ancient sedimentary rocks and generally is considered to reflect a phenotypic response to environmental variations rather than to evolutionary adaptation. Modern sulfate-reducing microorganisms isolated from similar environments can exhibit a wide range of sulfur isotope fractionations, suggesting that adaptive processes influence the sulfur isotope phenotype. To date, the relationship between evolutionary adaptation and isotopic phenotypes has not been explored. We addressed this by studying the covariation of fitness, sulfur isotope fractionation, and growth characteristics in Desulfovibrio vulgaris Hildenborough in a microbial evolution experiment. After 560 generations, the mean fitness of the evolved lineages relative to the starting isogenic population had increased by ∼ 17%. After 927 generations, the mean fitness relative to the initial ancestral population had increased by ∼ 20%. Growth rate in exponential phase increased during the course of the experiment, suggesting that this was a primary influence behind the fitness increases. Consistent changes were observed within different selection intervals between fractionation and fitness. Fitness changes were associated with changes in exponential growth rate but changes in fractionation were not. Instead, they appeared to be a response to changes in the parameters that govern growth rate: yield and cell-specific sulfate respiration rate. We hypothesize that cell-specific sulfate respiration rate, in particular, provides a bridge that allows physiological controls on fractionation to cross over to the adaptive realm. PMID:25662968

  12. Sulfur isotope fractionation during the evolutionary adaptation of a sulfate-reducing bacterium.

    PubMed

    Pellerin, André; Anderson-Trocmé, Luke; Whyte, Lyle G; Zane, Grant M; Wall, Judy D; Wing, Boswell A

    2015-04-01

    Dissimilatory sulfate reduction is a microbial catabolic pathway that preferentially processes less massive sulfur isotopes relative to their heavier counterparts. This sulfur isotope fractionation is recorded in ancient sedimentary rocks and generally is considered to reflect a phenotypic response to environmental variations rather than to evolutionary adaptation. Modern sulfate-reducing microorganisms isolated from similar environments can exhibit a wide range of sulfur isotope fractionations, suggesting that adaptive processes influence the sulfur isotope phenotype. To date, the relationship between evolutionary adaptation and isotopic phenotypes has not been explored. We addressed this by studying the covariation of fitness, sulfur isotope fractionation, and growth characteristics in Desulfovibrio vulgaris Hildenborough in a microbial evolution experiment. After 560 generations, the mean fitness of the evolved lineages relative to the starting isogenic population had increased by ∼ 17%. After 927 generations, the mean fitness relative to the initial ancestral population had increased by ∼ 20%. Growth rate in exponential phase increased during the course of the experiment, suggesting that this was a primary influence behind the fitness increases. Consistent changes were observed within different selection intervals between fractionation and fitness. Fitness changes were associated with changes in exponential growth rate but changes in fractionation were not. Instead, they appeared to be a response to changes in the parameters that govern growth rate: yield and cell-specific sulfate respiration rate. We hypothesize that cell-specific sulfate respiration rate, in particular, provides a bridge that allows physiological controls on fractionation to cross over to the adaptive realm.

  13. Insights into Paleogene biogeochemistry from coupled carbon and sulfur isotopes in foraminiferal calcite.

    NASA Astrophysics Data System (ADS)

    Rennie, V.; Paris, G.; Abramovitch, S.; Sessions, A. L.; Adkins, J. F.; Turchyn, A. V.

    2014-12-01

    The Paleogene witnessed large-scale environmental changes, including the beginning of long-term Cenozoic cooling. The carbon isotope composition of foraminiferal calcite suggests a major reorganization of the carbon cycle over the Paleogene, with enhanced organic carbon burial in the Paleocene, and subsequent oxidation of this organic carbon or increased volcanism throughout the Eocene. The sulfur cycle is linked to the carbon cycle via the breakdown of organic carbon during bacterial sulfate reduction. Over geological time, carbon and sulfur isotopic shifts are often coupled due to enhanced pyrite burial being coupled to enhanced organic carbon burial, and enhanced pyrite weathering being coupled to enhanced organic carbon weathering. However, over the Paleogene, carbon and sulfur isotopes are fully decoupled, with the sulfur isotope record showing only one major shift in the early Eocene, after most of the carbon isotope variability is complete. One complication of interpreting the evolution of the sulfur cycle over the Cenozoic, is the fact that the mineral proxies used (typically barite) may not be temporally coincident with those used to reconstruct the carbon cycle (typically carbonate). Furthermore, these minerals are preserved in different locations, and therefore often must be extracted from different sediment cores in different ocean basins, leading to age-model uncertainty when the records are merged. To properly ascertain the phasing between early Cenozoic changes in the carbon cycle and the sulfur cycle, we would ideally measure all isotope records on the same mineral. A new sulfur isotope analytical technique [1] has been optimised for foraminiferal calcite as a proxy for seawater δ34SSO4. The δ34SSO4 in foraminiferal calcite can then be tied to records of carbon isotopes from stratigraphically identical samples, resolving previous age model uncertainties. We present coupled carbon and sulfur isotope records from the same core over the early

  14. Combined S-33 and O-18 Isotope Tracing of Intracellular Sulfur Metabolism during Microbial Sulfate Reduction

    NASA Astrophysics Data System (ADS)

    Antler, Gilad; Bosak, Tanja; Ono, Shuhei; Sivan, Orit; Turchyn, Alexandra V.

    2014-05-01

    Microbial sulfate reduction is a key player in the global carbon cycle, oxidizing nearly 50% of organic matter in marine sediments. The biochemical pathway of microbial sulfate reduction fractionates sulfur and oxygen isotopes and these fractionations can be used to reconstruct S cycling in sediments. Sulfur isotope fractionation during microbial sulfate reduction, which partitions lighter sulfur (32S) into sulfide and heavier sulfur (33S and 34S) into the residual sulfate, can be as high as 72o for 34S/32S. The availability and type of organic substrate control the magnitude of sulfur isotope fractionation by influencing the fluxes of and the transfer of electrons to different S species. The partitioning of oxygen in sulfate during microbial sulfate reduction appears to be strongly influenced by the oxygen isotopic composition of water in which the bacteria grow, but its magnitude also seems to correlate with the magnitude of 34S/32S isotope fractionation. In addition, the fractionation of 33S/32S is thought to reflect the reversibility of some intercellular fluxes. We wanted to investigate whether the 18O/16O, 34S/32S and 33S/32S isotope fractionations in sulfate are controlled by the same intracellular processes and conditions. This was done by investigating the combined sulfur and oxygen isotope partitioning by a marine Desulfovibrio sp. grown in pure culture on different organic substrates and in water with different isotopic composition of oxygen. The isotope fractionations of oxygen and sulfur correlated with the cell specific sulfate reduction rates (csSRR), where slower rates yielded higher sulfur fractionation (as high as 60) and higher oxygen isotope fractionation. The trends in 33S/32S and 34S/32S with the changing csSRR was similar to the trends in 18O/16O with the csSRR, suggesting that the same intercellular pathways controlled both oxygen and sulfur isotope signatures during microbial sulfate reduction. The use of water with different isotopic

  15. Sulfur and carbon isotope biogeochemistry of a rewetted brackish fen

    NASA Astrophysics Data System (ADS)

    Koebsch, Franziska; Gehre, Matthias; Winkel, Matthias; Koehler, Stefan; Koch, Marian; Jurasinski, Gerald; Spitzy, Alejandro; Liebner, Susanne; Sachs, Torsten; Schmiedinger, Iris; Kretzschmann, Lisett; Saborowski, Anke; Böttcher, Michael E.

    2015-04-01

    Sea coast line exhibited a significant excess of sulfate. Preliminary sulfur isotope analysis of pore water sulfate from a location nearest to this profile revealed an enrichment in 34S (24.9 to 41.8o ) in comparison to Baltic Sea sulfate (21o ). This confirms high degrees of net sulfate reduction. Considering the yet high sulfate concentrations we hypothesize that local processes might supply additional sulfate and that the sulfide produced from sulfate reduction might either be lost by upwards diffusion towards the atmosphere or converted into other S compounds such as pyrite or organic compounds. The isotopic signatures of methane (δ13C: -68 to -57o and δ2H: -133 to -157o respectively) indicated acetoclastic methanogenesis to be the most dominant methane production pathway. However, estimated fractionation factors are comparatively high (1.050-1.065). Enrichment of heavy 13C in methane at the top of the sediment was either caused by methane oxidation or variation in substrate availability (e. g. due to peat degradation). The interpretation of our data in the light of further results will provide deeper insights into metabolic pathways and possible interactions between both coupled element cycles for coastal ecosystems.

  16. Natural variations of copper and sulfur stable isotopes in blood of hepatocellular carcinoma patients.

    PubMed

    Balter, Vincent; Nogueira da Costa, Andre; Bondanese, Victor Paky; Jaouen, Klervia; Lamboux, Aline; Sangrajrang, Suleeporn; Vincent, Nicolas; Fourel, François; Télouk, Philippe; Gigou, Michelle; Lécuyer, Christophe; Srivatanakul, Petcharin; Bréchot, Christian; Albarède, Francis; Hainaut, Pierre

    2015-01-27

    The widespread hypoxic conditions of the tumor microenvironment can impair the metabolism of bioessential elements such as copper and sulfur, notably by changing their redox state and, as a consequence, their ability to bind specific molecules. Because competing redox state is known to drive isotopic fractionation, we have used here the stable isotope compositions of copper ((65)Cu/(63)Cu) and sulfur ((34)S/(32)S) in the blood of patients with hepatocellular carcinoma (HCC) as a tool to explore the cancer-driven copper and sulfur imbalances. We report that copper is (63)Cu-enriched by ∼0.4‰ and sulfur is (32)S-enriched by ∼1.5‰ in the blood of patients compared with that of control subjects. As expected, HCC patients have more copper in red blood cells and serum compared with control subjects. However, the isotopic signature of this blood extra copper burden is not in favor of a dietary origin but rather suggests a reallocation in the body of copper bound to cysteine-rich proteins such as metallothioneins. The magnitude of the sulfur isotope effect is similar in red blood cells and serum of HCC patients, implying that sulfur fractionation is systemic. The (32)S-enrichment of sulfur in the blood of HCC patients is compatible with the notion that sulfur partly originates from tumor-derived sulfides. The measurement of natural variations of stable isotope compositions, using techniques developed in the field of Earth sciences, can provide new means to detect and quantify cancer metabolic changes and provide insights into underlying mechanisms.

  17. Natural variations of copper and sulfur stable isotopes in blood of hepatocellular carcinoma patients

    PubMed Central

    Balter, Vincent; Nogueira da Costa, Andre; Bondanese, Victor Paky; Jaouen, Klervia; Lamboux, Aline; Sangrajrang, Suleeporn; Vincent, Nicolas; Fourel, François; Télouk, Philippe; Gigou, Michelle; Lécuyer, Christophe; Srivatanakul, Petcharin; Bréchot, Christian; Albarède, Francis; Hainaut, Pierre

    2015-01-01

    The widespread hypoxic conditions of the tumor microenvironment can impair the metabolism of bioessential elements such as copper and sulfur, notably by changing their redox state and, as a consequence, their ability to bind specific molecules. Because competing redox state is known to drive isotopic fractionation, we have used here the stable isotope compositions of copper (65Cu/63Cu) and sulfur (34S/32S) in the blood of patients with hepatocellular carcinoma (HCC) as a tool to explore the cancer-driven copper and sulfur imbalances. We report that copper is 63Cu-enriched by ∼0.4‰ and sulfur is 32S-enriched by ∼1.5‰ in the blood of patients compared with that of control subjects. As expected, HCC patients have more copper in red blood cells and serum compared with control subjects. However, the isotopic signature of this blood extra copper burden is not in favor of a dietary origin but rather suggests a reallocation in the body of copper bound to cysteine-rich proteins such as metallothioneins. The magnitude of the sulfur isotope effect is similar in red blood cells and serum of HCC patients, implying that sulfur fractionation is systemic. The 32S-enrichment of sulfur in the blood of HCC patients is compatible with the notion that sulfur partly originates from tumor-derived sulfides. The measurement of natural variations of stable isotope compositions, using techniques developed in the field of Earth sciences, can provide new means to detect and quantify cancer metabolic changes and provide insights into underlying mechanisms. PMID:25583489

  18. Natural variations of copper and sulfur stable isotopes in blood of hepatocellular carcinoma patients

    NASA Astrophysics Data System (ADS)

    Balter, Vincent; Nogueira da Costa, Andre; Paky Bondanese, Victor; Jaouen, Klervia; Lamboux, Aline; Sangrajrang, Suleeporn; Vincent, Nicolas; Fourel, François; Télouk, Philippe; Gigou, Michelle; Lécuyer, Christophe; Srivatanakul, Petcharin; Bréchot, Christian; Albarède, Francis; Hainaut, Pierre

    2015-01-01

    The widespread hypoxic conditions of the tumor microenvironment can impair the metabolism of bioessential elements such as copper and sulfur, notably by changing their redox state and, as a consequence, their ability to bind specific molecules. Because competing redox state is known to drive isotopic fractionation, we have used here the stable isotope compositions of copper (65Cu/63Cu) and sulfur (34S/32S) in the blood of patients with hepatocellular carcinoma (HCC) as a tool to explore the cancer-driven copper and sulfur imbalances. We report that copper is 63Cu-enriched by ∼0.4‰ and sulfur is 32S-enriched by ∼1.5‰ in the blood of patients compared with that of control subjects. As expected, HCC patients have more copper in red blood cells and serum compared with control subjects. However, the isotopic signature of this blood extra copper burden is not in favor of a dietary origin but rather suggests a reallocation in the body of copper bound to cysteine-rich proteins such as metallothioneins. The magnitude of the sulfur isotope effect is similar in red blood cells and serum of HCC patients, implying that sulfur fractionation is systemic. The 32S-enrichment of sulfur in the blood of HCC patients is compatible with the notion that sulfur partly originates from tumor-derived sulfides. The measurement of natural variations of stable isotope compositions, using techniques developed in the field of Earth sciences, can provide new means to detect and quantify cancer metabolic changes and provide insights into underlying mechanisms.

  19. Isotope evidence for the microbially mediated formation of elemental sulfur: A case study from Lake Peten Itza, Guatemala

    NASA Astrophysics Data System (ADS)

    Turchyn, A. V.; Bennett, V. A.; Hodell, D. A.

    2013-12-01

    Elemental, or native, sulfur nodules or veins can be formed during aqueous diagenesis and have been found in a range of natural environments, including lake sediments. What governs the formation of elemental sulfur remains enigmatic, although it is widely thought to be microbially-mediated. While most of the literature suggests elemental sulfur is formed by partial re-oxidation of hydrogen sulphide, elemental sulfur can also form during incomplete bacterial sulfate reduction or during aborted sulfur disproportionation. Lake Peten Itza, in Northern Guatemala, which was cored during the International Continental Drilling program in 2006, is one of the few places where elemental sulfur nodules are forming during microbial diagenesis today. Sulfur isotopes are strongly partitioned during bacterial sulfate reduction and the magnitude of the partitioning yields insight into the microbial reactions and environmental conditions. For example, sulfate reduction that terminates at elemental sulfur likely requires the use of the intracellular trithonite pathway, which may drive larger overall sulfur isotope fractionation between the precursor sulfate and the elemental sulfur product. Sulfur isotopes combined with oxygen isotopes in the precursor sulfate may provide even more information about microbial mechanisms. We present coupled pore fluid sulfate concentrations and sulfur and oxygen isotope measurements, as well as co-existing nodule sulfur isotopes from the Lake Peten Itza sediments. The δ34S of the nodules in the lake sediments ranges from +12 to -13‰, often within a single nodule. This suggests formation from an open system where sulfate is replenished by diffusion, as might be expected during pore fluid diagenesis. The δ34S of the pore fluid sulfate at the depth of nodule formation is between 50 and 60‰ (versus the precursor gypsum which is 17 to 18‰) suggesting a large sulfur isotope fractionation between sulfate and elemental sulfur (38 to 73‰). Pyrite was

  20. Microbial sulfur metabolism evidenced from pore fluid isotope geochemistry at Site U1385

    NASA Astrophysics Data System (ADS)

    Turchyn, Alexandra V.; Antler, Gilad; Byrne, David; Miller, Madeline; Hodell, David A.

    2016-06-01

    At Site U1385, drilled during IODP Expedition 339 off the coast of Portugal on the continental slope, high-resolution sulfate concentration measurements in the pore fluids display non-steady-state behavior. At this site there is a zone of sulfate reduction in the uppermost seven meters of sediment, followed by a 38-meter interval where sulfate concentrations do not change, and finally sulfate concentrations are depleted to zero between 45 and 55 meters below seafloor. Below the sulfate minimum zone, there is abundant methane, suggesting that the lower sulfate consumption zone is coupled to anaerobic methane oxidation. We analyze pore water samples from IODP Site U1385 for sulfur and oxygen isotope ratios of dissolved sulfate, as well as the sulfur isotope composition of sedimentary pyrite. The sulfur isotopes in pore fluid sulfate display similar non-steady-state behavior similar to that of the sulfate concentrations, increasing over the uppermost zone of sulfate reduction and again over the lower zone of sulfate-driven anaerobic methane oxidation. The oxygen isotopes in sulfate increase to the 'apparent equilibrium' value in the uppermost zone of sulfate reduction and do not change further. Our calculations support the idea that sulfite to sulfide reduction is the limiting step in microbial sulfate reduction, and that the isotope fractionation expressed in the residual pore water sulfate pool is inversely proportional to the net sulfate reduction rate. The sulfur isotope composition of pyrite acquires one value in the uppermost sediments, which may be overprinted by a second value in the deeper sediments, possibly due to iron release during anaerobic methane oxidation or iron diffusion from a higher zone of bacterial iron reduction. Our results have implications for modeling the sulfur isotope composition of the pyrite burial flux in the global biogeochemical sulfur cycle.

  1. Effects of Iron and Nitrogen Limitation on Sulfur Isotope Fractionation during Microbial Sulfate Reduction

    PubMed Central

    Ono, Shuhei; Bosak, Tanja

    2012-01-01

    Sulfate-reducing microbes utilize sulfate as an electron acceptor and produce sulfide that is depleted in heavy isotopes of sulfur relative to sulfate. Thus, the distribution of sulfur isotopes in sediments can trace microbial sulfate reduction (MSR), and it also has the potential to reflect the physiology of sulfate-reducing microbes. This study investigates the relationship between the availability of iron and reduced nitrogen and the magnitude of S-isotope fractionation during MSR by a marine sulfate-reducing bacterium, DMSS-1, a Desulfovibrio species, isolated from salt marsh in Cape Cod, MA. Submicromolar levels of iron increase sulfur isotope fractionation by about 50% relative to iron-replete cultures of DMSS-1. Iron-limited cultures also exhibit decreased cytochrome c-to-total protein ratios and cell-specific sulfate reduction rates (csSRR), implying changes in the electron transport chain that couples carbon and sulfur metabolisms. When DMSS-1 fixes nitrogen in ammonium-deficient medium, it also produces larger fractionation, but it occurs at faster csSRRs than in the ammonium-replete control cultures. The energy and reducing power required for nitrogen fixation may be responsible for the reverse trend between S-isotope fractionation and csSRR in this case. Iron deficiency and nitrogen fixation by sulfate-reducing microbes may lead to the large observed S-isotope effects in some euxinic basins and various anoxic sediments. PMID:23001667

  2. Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere

    PubMed Central

    Shaheen, Robina; Abaunza, Mariana M.; Jackson, Teresa L.; McCabe, Justin; Savarino, Joël; Thiemens, Mark H.

    2014-01-01

    Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984–2001) showed the highest S-isotopic anomalies (Δ33S = +1.66‰ and Δ36S = +2‰) in a nonvolcanic (1998–1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997–1998)-induced changes in troposphere–stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ36S = −0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere. PMID:25092338

  3. Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere.

    PubMed

    Shaheen, Robina; Abaunza, Mariana M; Jackson, Teresa L; McCabe, Justin; Savarino, Joël; Thiemens, Mark H

    2014-08-19

    Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984-2001) showed the highest S-isotopic anomalies (Δ(33)S = +1.66‰ and Δ(36)S = +2‰) in a nonvolcanic (1998-1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997-1998)-induced changes in troposphere-stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ(36)S = -0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere.

  4. Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere.

    PubMed

    Shaheen, Robina; Abaunza, Mariana M; Jackson, Teresa L; McCabe, Justin; Savarino, Joël; Thiemens, Mark H

    2014-08-19

    Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984-2001) showed the highest S-isotopic anomalies (Δ(33)S = +1.66‰ and Δ(36)S = +2‰) in a nonvolcanic (1998-1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997-1998)-induced changes in troposphere-stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ(36)S = -0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere. PMID:25092338

  5. Fractionation of sulfur isotopes by Desulfovibrio vulgaris mutants lacking hydrogenases or type I tetraheme cytochrome c3

    PubMed Central

    Sim, Min Sub; Wang, David T.; Zane, Grant M.; Wall, Judy D.; Bosak, Tanja; Ono, Shuhei

    2013-01-01

    The sulfur isotope effect produced by sulfate reducing microbes is commonly used to trace biogeochemical cycles of sulfur and carbon in aquatic and sedimentary environments. To test the contribution of intracellular coupling between carbon and sulfur metabolisms to the overall magnitude of the sulfur isotope effect, this study compared sulfur isotope fractionations by mutants of Desulfovibrio vulgaris Hildenborough. We tested mutant strains lacking one or two periplasmic (Hyd, Hyn-1, Hyn-2, and Hys) or cytoplasmic hydrogenases (Ech and CooL), and a mutant lacking type I tetraheme cytochrome (TpI-c3). In batch culture, wild-type D. vulgaris and its hydrogenase mutants had comparable growth kinetics and produced the same sulfur isotope effects. This is consistent with the reported redundancy of hydrogenases in D. vulgaris. However, the TpI-c3 mutant (ΔcycA) exhibited slower growth and sulfate reduction rates in batch culture, and produced more H2 and an approximately 50% larger sulfur isotope effect, compared to the wild type. The magnitude of sulfur isotope fractionation in the CycA deletion strain, thus, increased due to the disrupted coupling of the carbon oxidation and sulfate reduction pathways. In continuous culture, wild-type D. vulgaris and the CycA mutant produced similar sulfur isotope effects, underscoring the influence of environmental conditions on the relative contribution of hydrogen cycling to the electron transport. The large sulfur isotope effects associated with the non-ideal stoichiometry of sulfate reduction in this study imply that simultaneous fermentation and sulfate reduction may be responsible for some of the large naturally-occurring sulfur isotope effects. Overall, mutant strains provide a powerful tool to test the effect of specific redox proteins and pathways on sulfur isotope fractionation. PMID:23805134

  6. Speciation and isotopic composition of sulfur in sediments from Jellyfish Lake, Palau

    USGS Publications Warehouse

    Bates, A.L.; Spiker, E. C.; Orem, W.H.; Burnett, W.C.

    1993-01-01

    Jellyfish Lake, Palau, is a meromictic marine lake with high organic productivity, low reactive Fe content, and anoxic bottom waters. Sediment samples from Jellyfish Lake were examined for the distribution of sulfur species and their isotopic signatures in order to gain a better understanding of sedimentary sulfur incorporation in Fe-poor environments. Surface samples were taken along a transect from a near-shore site to the center of the lake, and include a sample below oxic water, a sample below the chemocline layer, and samples below anoxic waters. Three additional samples were taken from a core, 2 m long, collected near the lake center. Sulfur to organic carbon weight ratios in all samples were lower than the expected value of 0.36 for normal marine sediment, probably because the lake water is deficient in reactive Fe to form iron sulfides. Total sulfur contents in the surface sediments indicated no changes with distance from shore; however, the sulfur content of the surface sample at the chemocline layer may be slightly higher. Total sulfur content increased with depth in the core and is inversely related to organic carbon content. Organic sulfur is the major sulfur species in the samples, followed in descending order by sulfate, disulfides and monosulfides. Sulfate sulfur isotope ??34S-values are positive (from +20.56 to +12.04???), reflecting the marine source of sulfate in Jellyfish Lake. Disulfide and monosulfide ??34S-values are negative (from -25.07 to -7.60???), because of fractionation during bacterial reduction of sulfate. Monosulfide ??34S-values are somewhat higher than those of disulfides, and they are close to the ??34S-values of organic sulfur. These results indicate that most of the organic sulfur is formed by reaction of bacteriogenic monosulfides, or possibly monosulfide-derived polysulfides, with organic matter in the sediment. ?? 1993.

  7. Oxygen and Sulfur Isotope Composition of Dissolved Sulfate in Interstitial Waters of the Great Australian Bight, ODP Leg 182.

    NASA Astrophysics Data System (ADS)

    Bernasconi, S. M.; Böttcher, M. E.; Wormann, U. G.

    2005-12-01

    We measured the sulfur and oxygen isotope composition of dissolved sulfides and sulfate at ODP Sites 1129, 1130, 1131 and 1132 in the Great Australian Bight (GAB). At all Sites, a saline brine is present in the subsurface as indicated by increasing chloride concentrations with depth to reach contents up to 3 times seawater. Sulfate also increases with depth but the concentrations are reduced by intense microbial sulfate reduction. The sulfur isotope fractionation between coexisting dissolved sulfate and sulfide is very large and reaches up to 70 ‰ at all studied Sites. Due to the high sulfide concentrations and the lack of a significant source of oxidants we consider that the large sulfur isotope fractionations are induced by sulfate reducing bacteria alone without a significant contribution of elemental sulfur disproportionation and sulfide oxidation processes. The oxygen isotope composition of dissolved sulfate reaches maximum values of approximately +27 ‰ vs. VSMOW at all sites, close to the equilibrium isotope fractionation between sulfate and water. The oxygen isotope composition of dissolved sulfate positively correlates with the sulfur isotope fractionation between sulfate and sulfide. These oxygen isotope data thus support the hypothesis that that the high sulfur isotope fractionation are related to a single step fractionation by sulfate reducing bacteria and do not involve significant sulfide oxidation reactions and/or elemental sulfur disproportionation. Sulfide oxidation processes would lead to a lowering of the oxygen isotope composition of residual sulfate. Elemental sulfur disproportionation has been shown to increase the oxygen isotope composition of sulfate but to a smaller extent than that that observed in the GAB. The patterns of the oxygen isotope increase with progressive sulfate reduction indicate a predominant influence of isotope exchange rather than a kinetic isotope fractionation controlling the oxygen isotope composition of sulfate

  8. Stable carbon and sulfur isotopes as records of the early biosphere

    NASA Technical Reports Server (NTRS)

    Desmarais, David J.

    1989-01-01

    The abundance ratios of the stable isotopes of light elements such as carbon and sulfur can differ between various naturally-occurring chemical compounds. If coexisting compounds have achieved mutual chemical and isotopic equilibrium, then the relative isotopic composition can record the conditions at which equilibrium was last maintained. If coexisting chemical compounds indeed formed simultaneously but had not achieved mutual equilibrium, then their relative isotopic compositions often reflect the conditions and mechanisms associated with the kinetically controlled reactions responsible for their production. In the context of Mars, the stable isotopic compositions of various minerals might record not only the earlier environmental conditions of the planet, but also whether or not the chemistry of life ever occurred there. Two major geochemical reservoirs occur in Earth's crust, both for carbon and sulfur. In rocks formed in low temperature sedimentary environments, the oxidized forms of these elements tend to be enriched in the isotope having the larger mass, relative to the reduced forms. In sediments where the organics and sulfides were formed by biological processes, these isotopic contrasts were caused by the processes of biological CO2 fixation and dissimilatory sulfate reduction. Such isotopic contrasts between oxidized and reduced forms of carbon and sulfur are permitted by thermodynamics at ambient temperatures. However, nonbiological chemical reactions associated with the production of organic matter and the reduction of organics and sulfides are extremely slow at ambient temperatures. Thus the synthesis of organics and sulfides under ambient conditions illustrates life's profound role as a chemical catalyst that has altered the chemistry of Earth's crust. Because the stable isotopes of carbon and sulfur can reflect their chemistry, they are useful probes of the Martian surface.

  9. Chemistry and isotope ratios of sulfur in basalts and volcanic gases at Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Sakai, H.; Casadevall, T.J.; Moore, J.G.

    1982-01-01

    Eighteen basalts and some volcanic gases from the submarine and subaerial parts of Kilauea volcano were analyzed for the concentration and isotope ratios of sulfur. By means of a newly developed technique, sulfide and sulfate sulfur in the basalts were separately but simultaneously determined. The submarine basalt has 700 ?? 100 ppm total sulfur with ??34S??s of 0.7 ?? 0.1 ???. The sulfate/sulfide molar ratio ranges from 0.15 to 0.56 and the fractionation factor between sulfate and sulfide is +7.5 ?? 1.5???. On the other hand, the concentration and ??34S??s values of the total sulfur in the subaerial basalt are reduced to 150 ?? 50 ppm and -0.8 ?? 0.2???, respectively. The sulfate to sulfide ratio and the fractionation factor between them are also smaller, 0.01 to 0.25 and +3.0???, respectively. Chemical and isotopic evidence strongly suggests that sulfate and sulfide in the submarine basalt are in chemical and isotopic equilibria with each other at magmatic conditions. Their relative abundance and the isotope fractionation factors may be used to estimate the f{hook}o2 and temperature of these basalts at the time of their extrusion onto the sea floor. The observed change in sulfur chemistry and isotopic ratios from the submarine to subaerial basalts can be interpreted as degassing of the SO2 from basalt thereby depleting sulfate and 34S in basalt. The volcanic sulfur gases, predominantly SO2, from the 1971 and 1974 fissures in Kilauea Crater have ??34S values of 0.8 to 0.9%., slightly heavier than the total sulfur in the submarine basalts and definitely heavier than the subaerial basalts, in accord with the above model. However, the ??34S value of sulfur gases (largely SO2) from Sulfur Bank is 8.0%., implying a secondary origin of the sulfur. The ??34S values of native sulfur deposits at various sites of Kilauea and Mauna Loa volcanos, sulfate ions of four deep wells and hydrogen sulfide from a geothermal well along the east rift zone are also reported. The high

  10. Stable isotope ratio mass spectrometry of nanogram quantities of boron and sulfur

    NASA Astrophysics Data System (ADS)

    Wieser, Michael Eugene

    1998-09-01

    Instrumentation and analytical techniques were developed to measure isotope abundances from nanograms of sulfur and boron. Sulfur isotope compositions were determined employing continuous flow isotope ratio mass spectroscopy (CF-IRMS) procedures and AsS+ thermal ionization mass spectrometry techniques (AsS+-TIMS). Boron isotope abundances were determined by BO2/sp--TIMS. CF-IRMS measurements realized δ34S values from 10 μg sulfur with precisions of ±0.3/perthous. To extend sulfur isotope measurements to much smaller samples, a TIMS procedure was developed to measure 75As32S+ and 75As34S+ at masses 108 and 109 from 200 ng S on a Finnigan MAT 262 with an ion counter. This is possibly the smallest amount of sulfur which has been successfully analyzed isotopically. The internal precision of 32S/34S ratios measured by AsS+-TIMS was better than ±0.15 percent. δ34S-values calculated relative to the measured 32S/34S value of an IAEA AG2S standard (S-1) agreed with those determined by CF-IRMS to within ±3/perthous. The increasing sensitivity of S-isotope analyses permits hiterto impossible investigations e.g. sulfur in tree rings and ice cores. Boron isotope abundances were measured as BO2/sp- from 50 ng B using an older thermal ionization mass spectrometer which had been extensively upgraded including the addition of computer control electronics, sensitive ion current amplification and fiber optic data bus. The internal precisions of the measured 11B/10B ratios were ±0.15 percent and the precisions of δ11B values calculated relative to the accepted international standard (SRM-951) were ±3/perthous. Two applications of boron isotope abundance variations were initiated (1) ground waters of Northern Alberta and (2) coffee beans in different regions of the world. In the first it was demonstrated that boron isotopes could be used to trace boron released during steam injection of oil sands into the surrounding environment. Data from the second study suggest that boron

  11. High sulfur isotope fractionation associated with anaerobic oxidation of methane in a low sulfate, iron rich environment

    NASA Astrophysics Data System (ADS)

    Weber, Hannah; Thamdrup, Bo; Habicht, Kirsten

    2016-06-01

    Sulfur isotope signatures provide key information for the study of microbial activity in modern systems and the evolution of the Earth surface redox system. Microbial sulfate reducers shift sulfur isotope distributions by discriminating against heavier isotopes. This discrimination is strain-specific and often suppressed at sulfate concentrations in the lower micromolar range that are typical to freshwater systems and inferred for ancient oceans. Anaerobic oxidation of methane (AOM) is a sulfate-reducing microbial process with a strong impact on global sulfur cycling in modern habitats and potentially in the geological past, but its impact on sulfur isotope signatures is poorly understood, especially in low sulfate environments. We investigated sulfur cycling and 34S fractionation in a low-sulfate freshwater sediment with biogeochemical conditions analogous to Early Earth environments. The zone of highest AOM activity was associated in situ with a zone of strong 34S depletions in the pool of reduced sulfur species, indicating a coupling of sulfate reduction and AOM at sulfate concentrations < 50 µmol L-1. In slurry incubations of AOM-active sediment, the addition of methane stimulated sulfate reduction and induced a bulk sulfur isotope effect of ~29 ‰. Our results imply that sulfur isotope signatures may be strongly impacted by AOM even at sulfate concentrations two orders of magnitude lower than at present oceanic levels. Therefore, we suggest that sulfur isotope fractionation during AOM must be considered when interpreting 34S signatures in modern and ancient environment.

  12. Sulfur and Hydrogen Isotope Anomalies in Organic Compounds from the Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, G. W.; Thiemens, M. H.; Jackson, T.; Chang, Sherwood

    1996-01-01

    Isotopic measurements have been made on organic sulfur and phosphorus compounds recently discovered in the Murchison meteorite. Carbon, hydrogen and sulfur measurements were performed on individual members of the organic sulfur compounds, alkyl sulfonates; and carbon and hydrogen measurements were made on bulk alkyl phosphonates. Cooper and Chang reported the first carbon isotopic measurements of Murchison organic sulfonates, providing insight into the potential synthetic mechanisms of these and, possibly, other organic species. Hydrogen isotopic measurements of the sulforiates now reveal deuterium excesses ranging from +660 to +2730 %. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low temperature astrophysical environment consistent with that of dense molecular clouds. Measurements of the sulfur isotopes provide further constraints on the origin and mechanism of formation of these organic molecules. Recently, there has been growing documentation of sulfur isotopic anomalies in meteoritic material. Thiemens and Jackson have shown that some bulk ureilites possess excess S-33 and Thiemens et al. have reported excess S-33 in an oldhamite separate from the Norton County meteorite. Rees and Thode reported a large S-33 excess in an Allende acid residue, however, attempts to verify this measurements have been unsuccessful, possibly due to the heterogeneous nature of the carrier phase. With the recognition that sulfur isotopes may reflect chemistry in the protosolar nebula or the precursor molecular cloud, identification of potential carriers is of considerable interest. In the present study, the stable isotopes of sulfur were measured in methane sulfonic acid extracted from the Murchison meteorite. The isotopic composition was found to be: (delta)S-33 = 2.48 %, (delta)S-34 = 2.49 % and (delta)S-36 = 6.76 %. Based upon analysis of more than 60 meteoritic and numerous terrestrial samples, the mass fractionation lines are

  13. Stable sulfur and nitrogen isotopic compositions of crude oil fractions from Southern Germany

    NASA Astrophysics Data System (ADS)

    Hirner, A. V.; Graf, W.; Treibs, R.; Melzer, A. N.; Hahn-Weinheimer, P.

    1984-11-01

    Eleven samples of crude oil from the Molasse Basin of Southern Germany were fractionated and their contents of sulfur and nitrogen as well as the stable isotope compositions of these elements ( 34S /32S and 15N /14N , resp.) investigated. According to the δ34S determinations, all crude oils from the Tertiary base of the Western and Eastern Molasse belong to one oil family and differ significantly from the Triassic and Liassic oils in the Western Molasse. An enrichment of 34S was observed with increasing polarity of crude oil fractions. The isotope distributions of sulfur in the polar constituents of the biodegraded oils from the sandstones of Ampfing, however, approach a homogeneous distribution. The nitrogen isotope distribution is rather uniform in Southern German oils. A regional differentiation can be recognized, although the overall isotopic variation is small. The δ15N values of the crudes and asphaltenes do not correlate.

  14. The minor sulfur isotope composition of Cretaceous and Cenozoic seawater sulfate

    NASA Astrophysics Data System (ADS)

    Masterson, A. L.; Wing, Boswell A.; Paytan, Adina; Farquhar, James; Johnston, David T.

    2016-06-01

    The last 125 Myr capture major changes in the chemical composition of the ocean and associated geochemical and biogeochemical cycling. The sulfur isotopic composition of seawater sulfate, as proxied in marine barite, is one of the more perplexing geochemical records through this interval. Numerous analytical and geochemical modeling approaches have targeted this record. In this study we extend the empirical isotope record of seawater sulfate to therefore include the two minor sulfur isotopes, 33S and 36S. These data record a distribution of values around means of Δ33S and Δ36S of 0.043 ± 0.016‰ and -0.39 ± 0.15‰, which regardless of δ34S-based binning strategy is consistent with a signal population of values throughout this interval. We demonstrate with simple box modeling that substantial changes in pyrite burial and evaporite sulfate weathering can be accommodated within the range of our observed isotopic values.

  15. Sulfur and Hydrogen Isotope Anomalies in Organic Compounds from the Murchison Meteorite

    NASA Astrophysics Data System (ADS)

    Cooper, G. W.; Thiemens, M. H.; Jackson, T.; Chang, S.

    1995-09-01

    Carbon, hydrogen and sulfur isotopic measurements have been made on individual members of a recently discovered class of organic sulfur compounds, alkyl sulfonates, in the Murchison meteorite. Cooper and Chang (1) reported the first carbon isotopic measurements of Murchison organic sulfonates, providing insight into potential synthetic mechanisms of these, and possibly other, organic species. Hydrogen isotopic measurements of the sulfonates now reveal deuterium excesses ranging from +660 to +2730 per mil. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low temperature astrophysical environment consistent with that of dense molecular clouds. Measurement of the sulfur isotopes provide further constraints on the origin and mechanism of formation of these organic molecules. Recently, there has been growing documentation of sulfur isotopic anomalies in meteoritic material. Thiemens and Jackson (2) have shown that some bulk ureilites possess excess 33S and Thiemens et al. (3) have reported excess 33S in an oldhamite separate from Norton County. Rees and Thode (4) reported a large 33S excess in an Allende acid residue, however, attempts to verify this measurement have been unsuccessful, possibly due to the heterogeneous nature of the carrier phase. With the recognition that sulfur isotopes may reflect nebular chemistry, identification of potential carriers is of considerable interest. In the present study the three stable isotopes of sulfur were measured in methane sulfonate extracted from the Murchison meteorite. The isotopic composition was found to be delta 33S=2.48, delta 34S=2.49 and delta 36S = 6.76 per mil. Based upon analysis of more than 60 meteoritic, and numerous terrestrial samples, the mass fractionation lines are defined by 33Delta = delta 33S-0.50 delta 34S and 36Delta = delta 36S -1.97 delta 34S. From these relations a 33Delta = 1.24 per mil and 36Delta = 0.89 per mil is observed. These anomalies

  16. Controls on stable sulfur isotope fractionation during bacterial sulfate reduction in Arctic sediments

    NASA Astrophysics Data System (ADS)

    Brüchert, Volker; Knoblauch, Christian; Jørgensen, Bo Barker

    2001-03-01

    Sulfur isotope fractionation experiments during bacterial sulfate reduction were performed with recently isolated strains of cold-adapted sulfate-reducing bacteria from Arctic marine sediments with year-round temperatures below 2°C. The bacteria represent quantitatively important members of a high-latitude anaerobic microbial community. In the experiments, cell-specific sulfate reduction rates decreased with decreasing temperature and were only slightly higher than the inferred cell-specific sulfate reduction rates in their natural habitat. The experimentally determined isotopic fractionations varied by less than 5.8‰ with respect to temperature and sulfate reduction rate, whereas the difference in sulfur isotopic fractionation between bacteria with different carbon oxidation pathways was as large as 17.4‰. Incubation of sediment slurries from two Arctic localities across an experimental temperature gradient from -4°C to 39°C yielded an isotopic fractionation of 30‰ below 7.6°C, a fractionation of 14‰ and 15.5‰ between 7.6°C and 25°C, and fractionations of 5‰ and 8‰ above 25°C, respectively. In absence of significant differences in sulfate reduction rates in the high and low temperature range, respectively, we infer that different genera of sulfate-reducing bacteria dominate the sulfate-reducing bacterial community at different temperatures. In the Arctic sediments where these bacteria are abundant the isotopic differences between dissolved sulfate, pyrite, and acid-volatile sulfide are at least twice as large as the experimentally determined isotopic fractionations. On the basis of bacterial abundance and cell-specific sulfate reduction rates, these greater isotopic differences cannot be accounted for by significantly lower in situ bacterial sulfate reduction rates. Therefore, the remaining isotopic difference between sulfate and sulfide must derive from additional isotope effects that exist in the oxidative part of the sedimentary sulfur

  17. Contrasting sulfur isotope records during the Late Devonian punctata and Upper Kellwasser events

    NASA Astrophysics Data System (ADS)

    Sim, M.; Ono, S.; Hurtgen, M. T.

    2013-12-01

    The Late Devonian was a period of intense biological and environmental changes, including terrestrial afforestation, a series of asteroid impacts, and active orogeny due to the accretion of continental blocks. High amplitude positive carbon isotope excursions, the punctata and Kellwasser events, reflect major perturbations in the global carbon cycle during this period, which have been attributed to increased continental weathering and subsequent ocean eutrophication. Despite the comparable carbon isotope anomalies, however, a global biological crisis has been reported only for the Kellwasser events, while very low extinction intensity characterizes the punctata Event. We will present sulfur isotope records of carbonate associated sulfate (CAS) and pyrite from Frasnian-Famennian sections in the Great Basin, USA, and evaluate the role of sulfur during the punctata and Upper Kellwasser events. A positive sulfur isotope shift in both CAS and pyrite accompanies the onset of the punctata Event, but with a larger extent in the latter. As a result, the sulfur isotope offset between CAS and pyrite (Δ34SCAS-py) plummeted to less than 10‰. In the middle of the punctata Event, a sharp negative δ34SCAS excursion occurred just after the Alamo Impact, leading to the negative Δ34SCAS-py values. Unlike the rapid oscillations of δ34Spy and δ34SCAS during the punctata Event, the Upper Kellwasser was a period of stability, except for a brief drop of δ34SCAS before the event. Paired sulfur isotope data, aided by a simple box model, suggests that geochemical cycle of sulfur might be responsible for the contrasting biological responses to these two events. Superheavy pyrite and high stratigraphic variability of δ34Spy and δ34SCAS demonstrate a relatively small oceanic sulfate pool during the punctata Event, and the Alamo Impact likely triggered to the rapid oxidation of microbially-produced sulfide. The expansion of sulfidic bottom water thus may have been impeded, thereby

  18. Sulfur isotope signals in molybdenite - a persistent message from the past

    NASA Astrophysics Data System (ADS)

    Stein, H. J.; Hannah, J. L.

    2010-12-01

    Trace elements in ore deposits, gleaned from minerals or isolated inclusions, are used by economic geologists to speculate on source and to model ore-forming processes. As well, sulfur isotope data are often obtained for sulfide minerals, but the interpretation of these isotopic data for understanding ore genesis has been thin - often simplistically concluding a “mantle source” or “crustal source”. With starting parameters for ore-bound metals that may include magmatic-hydrothermal components from lower crust with its own initial biogenic and redox history, subseqeuntly compromised by metamorphic processes, just about any source can be invoked to explain a measured range of sulfur isotopic data. Added constraints are essential. The sulfur isotopic composition of pyrite in magmatic-hydrothermal systems ranges widely, from negative to positive per mil values, as is also the case for other ore-forming sulfides of Cu, Pb, and Zn. In contrast, from Paleoarchean to Recent, the sulfur isotopic composition of molybdenite (molybdenum disulfide) is eerily consistent and decisively positive (δ34S commonly +2 to +6 per mil). This requires either an unwavering source for sulfur in all magmatic-hydrothermal molybdenites, and/or a template for a process that has been perfectly reproduced throughout earth history. A sedimentary sulfur source would have to be extraordinarily unique through time to fit the bill. Molybdenite, a common mineral in magmatic-hydrothermal ore deposits, is clearly tied to the magmatic system, occurring as disseminations and/or generations of veins spatially associated with evolved intrusive phases. Thus, the metals have traveled a finite distance from their source, forcing reliance on geochemical tracers to elucidate controlling processes. Molybdenum isotope ratios in molybdenite from some individual deposits span a large range of values, comparable to the range observed in all rock types. Rather than revealing source, the Mo isotopes reflect

  19. High-resolution sulfur isotopes in ice cores identify large stratospheric volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Burke, Andrea; Sigl, Michael; Adkins, Jess; Paris, Guillaume; McConnell, Joe

    2016-04-01

    The record of the volcanic forcing of climate over the past 2500 years is reconstructed primarily from sulfate concentrations in ice cores. Of particular interest are stratospheric eruptions, as these afford sulfate aerosols the longest residence time and largest dispersion in the atmosphere, and thus the greatest impact on radiative forcing. Identification of stratospheric eruptions currently relies on the successful matching of the same volcanic sulphate peak in ice cores from both the Northern and Southern hemispheres (a "bipolar event"). These are interpreted to reflect the global distribution of sulfur aerosols by the stratospheric winds. Despite its recent success, this method relies on precise and accurate dating of ice cores, in order to distinguish between a true 'bipolar event' and two separate eruptions that occurred in close temporal succession. Sulfur isotopes can been used to distinguish between these two scenarios since stratospheric sulfur aerosols are exposed to UV radiation which imparts a mass independent fractionation (Baroni et al., 2007). Mass independent fractionation of sulfate in ice cores thus offers a novel method of fingerprinting stratospheric eruptions, and thus refining the historic record of explosive volcanism and its forcing of climate. Here we present new high-resolution (sub-annual) sulfur isotope data from the Tunu Ice core in Greenland over seven eruptions. Sulfur isotopes were measured by MC-ICP-MS, which substantially reduces sample size requirements and allows high temporal resolution from a single ice core. We demonstrate the efficacy of the method on recent, well-known eruptions (including Pinatubo and Katmai/Novarupta), and then apply it to unidentified sulfate peaks, allowing us to identify new stratospheric eruptions. Baroni, M., Thiemens, M. H., Delmas, R. J., & Savarino, J. (2007). Mass-independent sulfur isotopic compositions in stratospheric volcanic eruptions. Science, 315(5808), 84-87. http://doi.org/10

  20. Fractionation of sulfur isotopes during heterogeneous oxidation of SO2 in the atmosphere

    NASA Astrophysics Data System (ADS)

    Harris, E. J.; Sinha, B.; Hoppe, P.; Crowley, J.; Borrmann, S.; Foley, S. F.; Gnauk, T.; Van Pinxteren, D.; Herrmann, H.

    2011-12-01

    Sulfate and sulfur dioxide play an important role in environmental chemistry and climate, particularly through their effect on aerosols. Processing of aerosol through sulfate addition in clouds, which causes both hygroscopicity changes and mass increases, has been shown to modify the cloud condensation nucleus spectrum, leading to important climatological effects (Bower et al. 1997, Hegg et al. 2004). However, the uptake of sulfate and SO2 to aerosol in clouds is not well constrained, nor is it resolved for different particle types and sizes (Kasper-Giebl et al. 2000, Barrie et al. 2001). Measurements of stable sulfur isotopes can be used to investigate the chemistry of SO2 in the environment, providing insight into sources, sinks and oxidation pathways. Typical isotopic compositions for many sources have been measured, and the major current limitation is the lack of reliable fractionation factors - characteristic changes in isotopic composition caused by chemical reactions - with which to interpret the data. Laboratory values of fractionation factors for the major oxidation reactions have been measured in previous work, however there are no measurements or models to represent isotopic fractionation during heterogeneous oxidation on complex atmospheric surfaces. In this work the sulfur isotopic fractionation factors for SO2 oxidation have been measured on Sahara dust, obtained from the Cape Verde Islands, and sea salt aerosol, which was synthesised in the laboratory according to Millero (1974), modified to contain no sulfate. Sulfur dioxide with a known isotopic composition was oxidised on these surfaces under a variety of conditions including irradiation and ozonation, and the sulfur isotopic composition of the product sulfate was measured with the Cameca NanoSIMS 50. These laboratory results were then used to investigate the uptake of sulfur to particles in an orographic cloud during the HCCT campaign. The campaign took place at the Schmücke mountain in Germany

  1. Sulfur isotope values in the sulfidic Frasassi cave system, central Italy: A case study of a chemolithotrophic S-based ecosystem

    NASA Astrophysics Data System (ADS)

    Zerkle, Aubrey L.; Jones, Daniel S.; Farquhar, James; Macalady, Jennifer L.

    2016-01-01

    Sulfide oxidation forms a critical step in the global sulfur cycle, although this process is notoriously difficult to constrain due to the multiple pathways and highly reactive intermediates involved. Multiple sulfur isotopes (δ34S and Δ33S) can provide a powerful tool for unravelling sulfur cycling processes in modern (and ancient) environments, although they have had limited application to systems with well-resolved oxidative S cycling. In this study, we report the major (δ34S) and minor (Δ33S) isotope values of sulfur compounds in streams and sediments from the sulfidic Frasassi cave system, Marche Region, Italy. These microaerophilic cave streams host prominent white biofilms dominated by chemolithotrophic organisms that oxidize sulfide to S0, allowing us to estimate S isotope fractionations associated with in situ sulfide oxidation and to evaluate any resulting isotope biosignatures. Our results demonstrate that chemolithotrophic sulfide oxidation produces 34S enrichments in the S0 products that are larger than those previously measured in laboratory experiments, with 34εS0-H2S of up to 8‰ calculated. These small reverse isotope effects are similar to those produced during phototrophic sulfide oxidation (⩽7‰), but distinct from the small normal isotope effects previously calculated for abiotic oxidation of sulfide with O2 (∼-5‰). An inverse correlation between the magnitude of 34εS0-H2S effects and sulfide availability, along with substantial differences in Δ33S, both support complex sulfide oxidation pathways and intracellular recycling of S intermediates by organisms inhabiting the biofilms. At the ecosystem level, we calculate fractionations of less than 40‰ between sulfide and sulfate in the water column and in the sediments. These fractionations are smaller than those typically calculated for systems dominated by sulfate reduction (>50‰), and contrast with the commonly held assumption that oxidative recycling of sulfide generally

  2. Sulfur isotope study of a modern intertidal environment, and the interpretation of ancient sulfides

    NASA Astrophysics Data System (ADS)

    Chambers, L. A.

    1982-05-01

    Extensive sulfur isotope distribution data for sulfides precipitated in an intertidal environment show no distinctive features when compared with isotope values for other marine, sedimentary sulfides. The fractionation ranges from α = 1.030 to α = 1.048. The pattern is characteristic for a system essentially open to sulfate, and isotope analyses of interstitial sulfates are corroborative. A population of sulfate-reducing bacteria of the order of 10 9 organisms per cc of interstitial water is indicated. Seasonal variation of the isotope distribution reflects a transient sulfide composition and a bacterial population in which the fractionation effect is indirectly controlled by temperature. The data presented for this modern shallow water environment are at variance with an earlier assessment of isotopic distributions in ancient sulfides which linked shallow water environments with limited fractionation (α ⩽ 1.025) in a closed system.

  3. Sulfur fluxes and isotopic compositions of the major rivers in China

    NASA Astrophysics Data System (ADS)

    Liu, C.; Lang, Y.; Tian, L.; Ding, H.; Strauss, H.; Zhao, Z.; Li, S.; Li, X.; Hu, J.

    2012-12-01

    Sulfur is widely distributed in the environment by volcanism, volatile emissions, precipitation, acid mine drainage and anthropogenic activity. Since the industrial revolution, the atmospheric sulfur cycle has been dominated by anthropogenic sources. Combustion of sulfur-containing fossil fuels release large quantities of sulfur dioxide into Earth's atmosphere annually. The cycling of sulfur, among those of many elements, is seriously disturbed by human activities at the earth's surface. Therefore, it is important to obtain a better understanding of sources and cycling processes of sulfur in river basins. For this purpose, we have measured the sulfur isotope composition of sulfate and its concentration for Changjiang (Yangtze River), Huanghe (Yellow River), Liaohe (Liao River), and Songhuajiang (Songhua River) in China. The sulfate fluxes of the major rivers in southern China are significantly larger as compared with the rivers in northern China. Sulfur isotopic compositions (δ34S) of sulfate in the rivers do not show a variation trend from southern to northern China. The sulfate δ34S values are 4.3‰~9.8‰ for Changjiang, 5.0‰~10.0‰ for most of river waters of Huanghe, and 2.0‰~27.0‰ for Songhuajiang. For Zhujiang (Pearl River), three sulfate δ34S values are from 1.0‰~6.9‰. The coal produced in southern China is generally of lower δ34S values as compared with that in northern China. The distributions of the sulfate δ34S values of the river waters of are generally lower in southern China, showing the contribution of atmospheric deposition of sulfur into the river water. Three main sources, atmospheric deposition (mostly anthropogenic), dissolution of sulfate evaporate, oxidation of sulfide minerals and/or sulfur-containing organic matter in soil, have been recognized for the sulfate in the rivers. Relative contributions of the different sulfur sources into the sulfate of the rivers are different, suggesting that sulfur cycling in the different

  4. Source of arsenic-bearing pyrite in southwestern Vermont, USA: sulfur isotope evidence.

    PubMed

    Mango, Helen; Ryan, Peter

    2015-02-01

    Arsenic-bearing pyrite is the source of arsenic in groundwater produced in late Cambrian and Ordovician gray and black slates and phyllites in the Taconic region of southwestern Vermont, USA. The aim of this study is to analyze the sulfur isotopic composition of this pyrite and determine if a relationship exists between pyrite δ(34)S and arsenic content. Pyrite occurs in both sedimentary/diagenetic (bedding-parallel layers and framboids) and low-grade metamorphic (porphyroblast) forms, and contains up to >2000 ppm As. The sulfur isotopic composition of arsenic-bearing pyrite ranges from -5.2‰ to 63‰. In the marine environment, the sulfur in sedimentary pyrite becomes increasingly enriched in (34)S as the geochemical environment becomes increasingly anoxic. There is a positive correlation between δ(34)S and arsenic content in the Taconic pyrite, suggesting that uptake of arsenic by pyrite increased as the environment became more reducing. This increased anoxia may have been due to a rise in sea level and/or tectonic activity during the late Cambrian and Ordovician. Low-grade metamorphism appears to have little effect on sulfur isotope composition, but does correlate with lower arsenic content in pyrite. New groundwater wells drilled in this region should therefore avoid gray and black slates and phyllites that contain sedimentary/diagenetic pyrite with heavy δ(34)S values.

  5. Source of arsenic-bearing pyrite in southwestern Vermont, USA: sulfur isotope evidence.

    PubMed

    Mango, Helen; Ryan, Peter

    2015-02-01

    Arsenic-bearing pyrite is the source of arsenic in groundwater produced in late Cambrian and Ordovician gray and black slates and phyllites in the Taconic region of southwestern Vermont, USA. The aim of this study is to analyze the sulfur isotopic composition of this pyrite and determine if a relationship exists between pyrite δ(34)S and arsenic content. Pyrite occurs in both sedimentary/diagenetic (bedding-parallel layers and framboids) and low-grade metamorphic (porphyroblast) forms, and contains up to >2000 ppm As. The sulfur isotopic composition of arsenic-bearing pyrite ranges from -5.2‰ to 63‰. In the marine environment, the sulfur in sedimentary pyrite becomes increasingly enriched in (34)S as the geochemical environment becomes increasingly anoxic. There is a positive correlation between δ(34)S and arsenic content in the Taconic pyrite, suggesting that uptake of arsenic by pyrite increased as the environment became more reducing. This increased anoxia may have been due to a rise in sea level and/or tectonic activity during the late Cambrian and Ordovician. Low-grade metamorphism appears to have little effect on sulfur isotope composition, but does correlate with lower arsenic content in pyrite. New groundwater wells drilled in this region should therefore avoid gray and black slates and phyllites that contain sedimentary/diagenetic pyrite with heavy δ(34)S values. PMID:24726513

  6. A comprehensive sulfur and oxygen isotope study of sulfur cycling in a shallow, hyper-euxinic meromictic lake

    NASA Astrophysics Data System (ADS)

    Gilhooly, William P.; Reinhard, Christopher T.; Lyons, Timothy W.

    2016-09-01

    Mahoney Lake is a permanently anoxic and sulfidic (euxinic) lake that has a dense plate of purple sulfur bacteria positioned at mid-water depth (∼7 m) where free sulfide intercepts the photic zone. We analyzed the isotopic composition of sulfate (δ34SSO4 and δ18OSO4), sulfide (δ34SH2S), and the water (δ18OH2O) to track the potentially coupled processes of dissimilatory sulfate reduction and phototrophic sulfide oxidation within an aquatic environment with extremely high sulfide concentrations (>30 mM). Large isotopic offsets observed between sulfate and sulfide within the monimolimnion (δ34SSO4-H2S = 51‰) and within pore waters along the oxic margin (δ34SSO4-H2S > 50‰) are consistent with sulfate reduction in both the sediments and the anoxic water column. Given the high sulfide concentrations of the lake, sulfur disproportionation is likely inoperable or limited to a very narrow zone in the chemocline, and therefore the large instantaneous fractionations are best explained by the microbial process of sulfate reduction. Pyrite extracted from the sediments reflects the isotopic composition of water column sulfide, suggesting that pyrite buried in the euxinic depocenter of the lake formed in the water column. The offset between sulfate and dissolved sulfide decreases at the chemocline (δ34SSO4-H2S = 37‰), a trend possibly explained by elevated sulfate reduction rates and inconsistent with appreciable disproportionation within this interval. Water column sulfate exhibits a linear response in δ18OSO4-δ34SSO4 and the slope of this relationship suggests relatively high sulfate reduction rates that appear to respond to seasonal changes in the productivity of purple sulfur bacteria. Although photosynthetic activity within the microbial plate influences the δ18OSO4-δ34SSO4 relationship, the biosignature for photosynthetic sulfur bacteria is restricted to the oxic/anoxic transition zone and is apparently minor relative to the more prevalent process of

  7. Evaporation and Accompanying Isotopic Fractionation of Sulfur from FE-S Melt During Shock Wave Heating

    NASA Technical Reports Server (NTRS)

    Tachibana, S.; Huss, G. R.; Miura, H.; Nakamoto, T.

    2004-01-01

    Chondrules probably formed by melting and subsequent cooling of solid precursors. Evaporation during chondrule melting may have resulted in depletion of volatile elements in chondrules. It is known that kinetic evaporation, especially evaporation from a melt, often leads to enrichment of heavy isotopes in an evaporation residue. However, no evidence for a large degree of heavy-isotope enrichment has been reported in chondrules for K, Mg, Si, and Fe (as FeO). The lack of isotopic fractionation has also been found for sulfur in troilites (FeS) within Bishunpur (LL3.1) and Semarkona (LL3.0) chondrules by an ion microprobe study. The largest fractionation, found in only one grain, was 2.7 +/- 1.4 %/amu, while all other troilite grains showed isotopic fractionations of <1 %/amu. The suppressed isotopic fractionation has been interpreted as results of (i) rapid heating of precursors at temperatures below the silicate solidus and (ii) diffusion-controlled evaporation through a surrounding silicate melt at temperatures above the silicate solidus. The kinetic evaporation model suggests that a rapid heating rate of >10(exp 4)-10(exp 6) K/h for a temperature range of 1000-1300 C is required to explain observed isotopic fractionations. Such a rapid heating rate seems to be difficult to be achieved in the X-wind model, but can be achieved in shock wave heating models. In this study, we have applied the sulfur evaporation model to the shock wave heating conditions of to evaluate evaporation of sulfur and accompanying isotopic fractionation during shock wave heating at temperatures below the silicate solidus.

  8. Sulfur isotopes track the global extent and dynamics of euxinia during Cretaceous Oceanic Anoxic Event 2.

    PubMed

    Owens, Jeremy D; Gill, Benjamin C; Jenkyns, Hugh C; Bates, Steven M; Severmann, Silke; Kuypers, Marcel M M; Woodfine, Richard G; Lyons, Timothy W

    2013-11-12

    The Mesozoic Era is characterized by numerous oceanic anoxic events (OAEs) that are diagnostically expressed by widespread marine organic-carbon burial and coeval carbon-isotope excursions. Here we present coupled high-resolution carbon- and sulfur-isotope data from four European OAE 2 sections spanning the Cenomanian-Turonian boundary that show roughly parallel positive excursions. Significantly, however, the interval of peak magnitude for carbon isotopes precedes that of sulfur isotopes with an estimated offset of a few hundred thousand years. Based on geochemical box modeling of organic-carbon and pyrite burial, the sulfur-isotope excursion can be generated by transiently increasing the marine burial rate of pyrite precipitated under euxinic (i.e., anoxic and sulfidic) water-column conditions. To replicate the observed isotopic offset, the model requires that enhanced levels of organic-carbon and pyrite burial continued a few hundred thousand years after peak organic-carbon burial, but that their isotope records responded differently due to dramatically different residence times for dissolved inorganic carbon and sulfate in seawater. The significant inference is that euxinia persisted post-OAE, but with its global extent dwindling over this time period. The model further suggests that only ~5% of the global seafloor area was overlain by euxinic bottom waters during OAE 2. Although this figure is ~30× greater than the small euxinic fraction present today (~0.15%), the result challenges previous suggestions that one of the best-documented OAEs was defined by globally pervasive euxinic deep waters. Our results place important controls instead on local conditions and point to the difficulty in sustaining whole-ocean euxinia.

  9. Sulfur isotopes track the global extent and dynamics of euxinia during Cretaceous Oceanic Anoxic Event 2.

    PubMed

    Owens, Jeremy D; Gill, Benjamin C; Jenkyns, Hugh C; Bates, Steven M; Severmann, Silke; Kuypers, Marcel M M; Woodfine, Richard G; Lyons, Timothy W

    2013-11-12

    The Mesozoic Era is characterized by numerous oceanic anoxic events (OAEs) that are diagnostically expressed by widespread marine organic-carbon burial and coeval carbon-isotope excursions. Here we present coupled high-resolution carbon- and sulfur-isotope data from four European OAE 2 sections spanning the Cenomanian-Turonian boundary that show roughly parallel positive excursions. Significantly, however, the interval of peak magnitude for carbon isotopes precedes that of sulfur isotopes with an estimated offset of a few hundred thousand years. Based on geochemical box modeling of organic-carbon and pyrite burial, the sulfur-isotope excursion can be generated by transiently increasing the marine burial rate of pyrite precipitated under euxinic (i.e., anoxic and sulfidic) water-column conditions. To replicate the observed isotopic offset, the model requires that enhanced levels of organic-carbon and pyrite burial continued a few hundred thousand years after peak organic-carbon burial, but that their isotope records responded differently due to dramatically different residence times for dissolved inorganic carbon and sulfate in seawater. The significant inference is that euxinia persisted post-OAE, but with its global extent dwindling over this time period. The model further suggests that only ~5% of the global seafloor area was overlain by euxinic bottom waters during OAE 2. Although this figure is ~30× greater than the small euxinic fraction present today (~0.15%), the result challenges previous suggestions that one of the best-documented OAEs was defined by globally pervasive euxinic deep waters. Our results place important controls instead on local conditions and point to the difficulty in sustaining whole-ocean euxinia. PMID:24170863

  10. Sulfur isotopes track the global extent and dynamics of euxinia during Cretaceous Oceanic Anoxic Event 2

    PubMed Central

    Owens, Jeremy D.; Gill, Benjamin C.; Jenkyns, Hugh C.; Bates, Steven M.; Severmann, Silke; Kuypers, Marcel M. M.; Woodfine, Richard G.; Lyons, Timothy W.

    2013-01-01

    The Mesozoic Era is characterized by numerous oceanic anoxic events (OAEs) that are diagnostically expressed by widespread marine organic-carbon burial and coeval carbon-isotope excursions. Here we present coupled high-resolution carbon- and sulfur-isotope data from four European OAE 2 sections spanning the Cenomanian–Turonian boundary that show roughly parallel positive excursions. Significantly, however, the interval of peak magnitude for carbon isotopes precedes that of sulfur isotopes with an estimated offset of a few hundred thousand years. Based on geochemical box modeling of organic-carbon and pyrite burial, the sulfur-isotope excursion can be generated by transiently increasing the marine burial rate of pyrite precipitated under euxinic (i.e., anoxic and sulfidic) water-column conditions. To replicate the observed isotopic offset, the model requires that enhanced levels of organic-carbon and pyrite burial continued a few hundred thousand years after peak organic-carbon burial, but that their isotope records responded differently due to dramatically different residence times for dissolved inorganic carbon and sulfate in seawater. The significant inference is that euxinia persisted post-OAE, but with its global extent dwindling over this time period. The model further suggests that only ∼5% of the global seafloor area was overlain by euxinic bottom waters during OAE 2. Although this figure is ∼30× greater than the small euxinic fraction present today (∼0.15%), the result challenges previous suggestions that one of the best-documented OAEs was defined by globally pervasive euxinic deep waters. Our results place important controls instead on local conditions and point to the difficulty in sustaining whole-ocean euxinia. PMID:24170863

  11. Regional source identification of atmospheric aerosols in Beijing based on sulfur isotopic compositions

    NASA Astrophysics Data System (ADS)

    Lianfang, Wei; Pingqing, Fu; Xiaokun, Han; Qingjun, Guo; Yele, Sun; Zifa, Wang

    2016-04-01

    65 daily PM2.5 (aerosol particle with aerodynamic diameter less than 2.5 μm) samples were collected from an urban site in Beijing in four months representing the four seasons between September 2013 and July 2014. Inorganic ions, organic/elemental carbon and stable sulfur isotopes of sulfate aerosols were analyzed systematically. The "fingerprint" characteristics of the stable sulfur isotopic composition, together with trajectory clustering modeled by HYSPLIT-4 and potential source contribution function (PSCF), were employed for identifying potential regional sources. Results obviously exhibited the distinctive seasonality for various aerosol speciation associated with PM2.5 in Beijing with sulfate, nitrate, ammonium, organic matter, and element carbon being the dominant species. Elevated chloride associated with higher concentration of organics were found in autumn and winter, due to enhanced coal combustion emissions. The δ34S values of Beijing aerosol samples ranged from 2.94‰ to 10.2‰ with an average value of 6.18±1.87‰ indicating that the major sulfur source is direct fossil fuel burning-related emissions. Owning to a temperature-dependent fractionation and elevated biogenic sources of isotopically light sulfur in summer, the δ34S values had significant seasonal variations with a winter maximum ( 8.6‰)and a summer minimum ( 5.0‰). The results of trajectory clustering and the PSCF method demonstrated that higher concentrations of sulfate with lower sulfur isotope ratios ( 4.83‰) were associated with air masses from the south, southeast or east, whereas lower sulfate concentrations with higher δ34S values ( 6.69‰) when the air masses were mainly from north or northwest. These results suggested two main different kinds of regional coal combustion sources contributed to the pollution in Beijing.

  12. Sulfur- and oxygen-isotopes in sediment-hosted stratiform barite deposits

    USGS Publications Warehouse

    Johnson, C.A.; Emsbo, P.; Poole, F.G.; Rye, R.O.

    2009-01-01

    Sulfur- and oxygen-isotope analyses have been obtained for sediment-hosted stratiform barite deposits in Alaska, Nevada, Mexico, and China to examine the environment of formation of this deposit type. The barite is contained in sedimentary sequences as old as Late Neoproterozoic and as young as Mississippian. If previously published data for other localities are considered, sulfur- and oxygen-isotope data are now available for deposits spanning a host-rock age range of Late Neoproterozoic to Triassic. On a ??34S versus ??18O diagram, many deposits show linear or concave-upward trends that project down toward the isotopic composition of seawater sulfate. The trends suggest that barite formed from seawater sulfate that had been isotopically modified to varying degrees. The ??34S versus ??18O patterns resemble patterns that have been observed in the modern oceans in pore water sulfate and water column sulfate in some anoxic basins. However, the closest isotopic analog is barite mineralization that occurs at fluid seeps on modern continental margins. Thus the data favor genetic models for the deposits in which barium was delivered by seafloor seeps over models in which barium was delivered by sedimentation of pelagic organisms. The isotopic variations within the deposits appear to reflect bacterial sulfate reduction operating at different rates and possibly with different electron donors, oxygen isotope exchange between reduction intermediates and H2O, and sulfate availability. Because they are isotopically heterogeneous, sediment-hosted stratiform barite deposits are of limited value in reconstructing the isotopic composition of ancient seawater sulfate.

  13. Sulfur- and oxygen-isotopes in sediment-hosted stratiform barite deposits

    NASA Astrophysics Data System (ADS)

    Johnson, Craig A.; Emsbo, Poul; Poole, Forrest G.; Rye, Robert O.

    2009-01-01

    Sulfur- and oxygen-isotope analyses have been obtained for sediment-hosted stratiform barite deposits in Alaska, Nevada, Mexico, and China to examine the environment of formation of this deposit type. The barite is contained in sedimentary sequences as old as Late Neoproterozoic and as young as Mississippian. If previously published data for other localities are considered, sulfur- and oxygen-isotope data are now available for deposits spanning a host-rock age range of Late Neoproterozoic to Triassic. On a δ 34S versus δ 18O diagram, many deposits show linear or concave-upward trends that project down toward the isotopic composition of seawater sulfate. The trends suggest that barite formed from seawater sulfate that had been isotopically modified to varying degrees. The δ 34S versus δ 18O patterns resemble patterns that have been observed in the modern oceans in pore water sulfate and water column sulfate in some anoxic basins. However, the closest isotopic analog is barite mineralization that occurs at fluid seeps on modern continental margins. Thus the data favor genetic models for the deposits in which barium was delivered by seafloor seeps over models in which barium was delivered by sedimentation of pelagic organisms. The isotopic variations within the deposits appear to reflect bacterial sulfate reduction operating at different rates and possibly with different electron donors, oxygen isotope exchange between reduction intermediates and H 2O, and sulfate availability. Because they are isotopically heterogeneous, sediment-hosted stratiform barite deposits are of limited value in reconstructing the isotopic composition of ancient seawater sulfate.

  14. Mass independent fractionation of sulfur isotopes during thermochemical reduction of native sulfur, sulfite and sulfate by amino acids

    NASA Astrophysics Data System (ADS)

    Watanabe, Y.; Naraoka, H.; Ohmoto, H.

    2006-05-01

    Mass independent fractionation of sulfur isotopes (MIF-S) is recognized when the Δ33S value (= δ33S-0.515xδ34S) of a sample falls outside the range of 0±0.2 permil and the 33-34θ value (= ln33α/ ln34α) lies outside the range of 0.515±.005 (Farquhar and Wing, 2003). Previous investigators have concluded that the only mechanisms to create MIF-S are photochemical reactions between sulfur-bearing gases (SO2, H2S) and UV. Based on comparisons of the geochemical characteristics of Archean sedimentary rocks between those with large MIF-S values (e.g., the 2.5 Ga McRae and 2.7 Ga Jeerinah shales) and those with no (or very small) MIF- S values (e.g., 2.76 Ga Hardey shales and 2.92 Ga Mosquito Creek shales), we have developed a hypothesis that MIF-S in sedimentary rocks may have been created by reactions among organic-rich sediments, sulfur- bearing solid compounds, and sulfur-bearing hydrothermal fluids at T = 100-200°C during the early diagenetic stage of sediments. Most abundant organic compounds in immature sediments are amino acids. For these reasons, we have conducted series of laboratory experiments to investigate sulfur isotope fractionations during reactions between a variety of amino acids (alanine, glycine, hystidine, etc.) and native sulfur, sodium sulfite or sodium sulfate at 150-200°C. Previous researchers used a variety of organic compounds (sugars, methane, xylene, etc) and/or ferrous- bearing minerals to investigate non-bacterial sulfate reduction, but they failed to demonstrate thermochemical sulfate reduction at temperatures below 230°C. However, we were able to reduce sulfate (S6+), as well as sulfite (S4+) and native sulfur (S0), to hydrogen sulfide (S2-) even at 150°C using simple and common amino acids (e.g., alanine and glycine). The reduction rates generally decreased: (a) from native sulfur, to sulfite, and to sulfate; (b) from simple amino acids to more complex amino acids (e.g., histidine); and (c) with decreasing temperatures. The

  15. Coupled sulfur and oxygen isotope insight into bacterial sulfate reduction in the natural environment

    NASA Astrophysics Data System (ADS)

    Antler, Gilad; Turchyn, Alexandra V.; Rennie, Victoria; Herut, Barak; Sivan, Orit

    2013-10-01

    We present new sulfur and oxygen isotope data in sulfate (δ34SSO4 and δ18OSO4, respectively), from globally distributed marine and estuary pore fluids. We use this data with a model of the biochemical steps involved in bacterial sulfate reduction (BSR) to explore how the slope on a δ18OSO4 vs. δ34SSO4 plot relates to the net sulfate reduction rate (nSRR) across a diverse range of natural environments. Our data demonstrate a correlation between the nSRR and the slope of the relative evolution of oxygen and sulfur isotopes (δ18OSO4 vs. δ34SSO4) in the residual sulfate pool, such that higher nSRR results in a lower slope (sulfur isotopes increase faster relative to oxygen isotopes). We combine these results with previously published literature data to show that this correlation scales over many orders of magnitude of nSRR. Our model of the mechanism of BSR indicates that the critical parameter for the relative evolution of oxygen and sulfur isotopes in sulfate during BSR in natural environments is the rate of intracellular sulfite oxidation. In environments where sulfate reduction is fast, such as estuaries and marginal marine environments, this sulfite reoxidation is minimal, and the δ18OSO4 increases more slowly relative to the δ34SSO4. In contrast, in environments where sulfate reduction is very slow, such as deep sea sediments, our model suggests sulfite reoxidation is far more extensive, with as much as 99% of the sulfate being thus recycled; in these environments the δ18OSO4 increases much more rapidly relative to the δ34SSO4. We speculate that the recycling of sulfite plays a physiological role during BSR, helping maintain microbial activity where the availability of the electron donor (e.g. available organic matter) is low.

  16. Sulfur isotopic analysis of carbonyl sulfide and its application for biogeochemical cycles

    NASA Astrophysics Data System (ADS)

    Hattori, Shohei; Kamezaki, Kazuki; Ogawa, Takahiro; Toyoda, Sakae; Katayama, Yoko; Yoshida, Naohiro

    2016-04-01

    Carbonyl sulfide (OCS or COS) is the most abundant gas containing sulfur in the atmosphere, with an average mixing ratio of 500 p.p.t.v. in the troposphere. OCS is suggested as a sulfur source of the stratospheric sulfate aerosols (SSA) which plays an important role in Earth's radiation budget and ozone depletion. Therefore, OCS budget should be validated for prediction of climate change, but the global OCS budget is imbalance. Recently we developed a promising new analytical method for measuring the stable sulfur isotopic compositions of OCS using nanomole level samples: the direct isotopic analytical technique of on-line gas chromatography-isotope ratio mass spectrometry (GC-IRMS) using fragmentation ions S+ (Hattori et al., 2015). The first measurement of the δ34S value for atmospheric OCS coupled with isotopic fractionation for OCS sink reactions in the stratosphere (Hattori et al., 2011; Schmidt et al., 2012; Hattori et al., 2012) explains the reported δ34S value for background stratospheric sulfate, suggesting that OCS is a potentially important source for background (nonepisodic or nonvolcanic) stratospheric sulfate aerosols. This new method measuring δ34S values of OCS can be used to investigate OCS sources and sinks in the troposphere to better understand its cycle. It is known that some microorganisms in soil can degrade OCS, but the mechanism and the contribution to the OCS in the air are still uncertain. In order to determine sulfur isotopic enrichment factor of OCS during degradation via microorganisms, incubation experiments were conducted using strains belonging to the genera Mycobacterium, Williamsia and Cupriavidus, isolated from natural soil environments (Kato et al., 2008). As a result, sulfur isotope ratios of OCS were increased during degradation of OCS, indicating that reaction for OC32S is faster than that for OC33S and OC34S. OCS degradation via microorganisms is not mass-independent fractionation (MIF) process, suggesting that this

  17. Sulfur Isotope Analysis of Minerals and Fluids in a Natural CO2 Reservoir, Green River, Utah

    NASA Astrophysics Data System (ADS)

    Chen, F.; Kampman, N.; Bickle, M. J.; Busch, A.; Turchyn, A. V.

    2013-12-01

    Predicting the security of geological CO2 storage sites requires an understanding of the geochemical behavior of the stored CO2, especially of fluid-rock reactions in reservoirs, caprocks and fault zones. Factors that may influence geochemical behavior include co-injection of sulfur gases along with the CO2, either in acid-gas disposal or as contaminants in CO2 storage sites, and microbial activity, such as bacterial sulfate reduction. The latter may play an important role in buffering the redox chemistry of subsurface fluids, which could affect toxic trace metal mobilization and transport in acidic CO2-rich fluids. These processes involving sulfur are poorly understood. Natural CO2-reservoirs provide natural laboratories, where the flow and reactions of the CO2-charged fluids and the activity of microbial communities are integrated over sufficient time-scales to aid prediction of long-term CO2 storage. This study reports on sulfur isotope analyses of sulfate and sulfide minerals in rock core and in CO2-charged fluids collected from a stacked sequence of natural CO2 reservoirs at Green River, Utah. Scientific drilling adjacent to a CO2-degassing normal fault to a depth of 325m retrieved core and fluid samples from two CO2 reservoirs in the Entrada and Navajo Sandstones and from the intervening Carmel Formation caprock. Fluid samples were collected from CO2-charged springs that discharge through the faults. Sulfur exists as sulfate in the fluids, as sedimentary gypsum beds in the Carmel Formation, as remobilized gypsum veins within a fault damage zone in the Carmel Fm. and in the Entrada Sandstone, and as disseminated pyrite and pyrite-mineralized open fractures throughout the cored interval. We use the stable sulfur (δ34S) and oxygen (δ18OSO4) isotopes of the sulfate, gypsum, and pyrite to understand the source of sulfur in the reservoir as well as the timing of gypsum vein and pyrite formation. The hydration water of the gypsum is also reported to explore the

  18. Stable sulfur isotope partitioning during simulated petroleum formation as determined by hydrous pyrolysis of Ghareb Limestone, Israel

    USGS Publications Warehouse

    Amrani, A.; Lewan, M.D.; Aizenshtat, Zeev

    2005-01-01

    Hydrous pyrolysis experiments at 200 to 365??C were carried out on a thermally immature organic-rich limestone containing Type-IIS kerogen from the Ghareb Limestone in North Negev, Israel. This work focuses on the thermal behavior of both organic and inorganic sulfur species and the partitioning of their stable sulfur isotopes among organic and inorganic phases generated during hydrous pyrolyses. Most of the sulfur in the rock (85%) is organic sulfur. The most dominant sulfur transformation is cleavage of organic-bound sulfur to form H2 S(gas). Up to 70% of this organic sulfur is released as H2S(gas) that is isotopically lighter than the sulfur in the kerogen. Organic sulfur is enriched by up to 2??? in 34S during thermal maturation compared with the initial ??34S values. The ??34S values of the three main organic fractions (kerogen, bitumen and expelled oil) are within 1??? of one another. No thermochemical sulfate reduction or sulfate formation was observed during the experiments. The early released sulfur reacted with available iron to form secondary pyrite and is the most 34S depleted phase, which is 21??? lighter than the bulk organic sulfur. The large isotopic fractionation for the early formed H2S is a result of the system not being in equilibrium. As partial pressure of H2S(gas) increases, retro reactions with the organic sulfur in the closed system may cause isotope exchange and isotopic homogenization. Part of the ??34S-enriched secondary pyrite decomposes above 300??C resulting in a corresponding decrease in the ??34S of the remaining pyrite. These results are relevant to interpreting thermal maturation processes and their effect on kerogen-oil-H2S-pyrite correlations. In particular, the use of pyrite-kerogen ??34S relations in reconstructing diagenetic conditions of thermally mature rocks is questionable because formation of secondary pyrite during thermal maturation can mask the isotopic signature and quantity of the original diagenetic pyrite. The

  19. Contrasting sulfur isotope compositions of sulfide minerals between on-ridge and off-ridge hydrothermal fields in the southern Mariana back-arc region

    NASA Astrophysics Data System (ADS)

    Kakegawa, T.

    2004-12-01

    New submarine hydrothermal fields were discovered in the southern Mariana back-arc spreading region during the Yokosuka-Shinkai 6500 cruise (October, 2003). One is located on the ridge of spreading center and the other is located on the off-rige site: A low-temperature hydrothermal activity and 10 m-high sulfide chimneys were found on the ridge site and the black-smoker activity with various sulfide chimneys was found on the top of the off-ridge seamount. Both hydrothermal fields were directly drilled by the benthic-multiple coring system during the Hakurei 2 cruise (February, 2004), in order to examine the subsurface hydrothermal processes. Elemental maps of drilled core samples and surface chimneys were constructed using X-ray scanning microscope, and an alteration pattern and types of sulfide minerals were examined. Forming steps of Fe-rich clays near the seafloor were traced and vesicle-filling process by clays and sulfides were found in the examined samples. Sulfur isotope analyses were performed using EA-IRMS on the separated sulfide and sulfate minerals. Sulfur isotope compositions of sulfate minerals are the identical to the seawater sulfate value. Sulfur isotope compositions of sulfides range from +2.9 to +8.7?n at the on-ridge site and _|3.2 to +3.6 ?n at the off-ridge site, respectively. Such regional difference in sulfur isotope compositions of sulfides is probably reflecting the difference in crustal processes: either (1) involvement of sulfate reduction near the discharge zone or (2) isotope exchange among several sulfide and sulfate phases in the deep reaction zone. Chronological change of sulfur isotope compositions was also found in each region: lighter sulfur isotope compositions were found in the younger generation of sulfides. This suggests the style of sulfur cycle in the basaltic crusts (e.g., depth and temperature change for sulfate reduction, potential biological process, etc.) are varying through the development and/or decay of each

  20. Rapid and high-precision measurement of sulfur isotope and sulfur concentration in sediment pore water by multi-collector inductively coupled plasma mass spectrometry.

    PubMed

    Bian, Xiao-Peng; Yang, Tao; Lin, An-Jun; Jiang, Shao-Yong

    2015-01-01

    We have developed a technique for the rapid, precise and accurate determination of sulfur isotopes (δ(34)S) by MC-ICP-MS applicable to a range of sulfur-bearing solutions of different sulfur content. The 10 ppm Alfa-S solution (ammonium sulfate solution, working standard of the lab of the authors) was used to bracket other Alfa-S solutions of different concentrations and the measured δ(34)SV-CDT values of Alfa-S solutions deviate from the reference value to varying degrees (concentration effect). The stability of concentration effect has been verified and a correction curve has been constructed based on Alfa-S solutions to correct measured δ(34)SV-CDT values. The curve has been applied to AS solutions (dissolved ammonium sulfate from the lab of the authors) and pore water samples successfully, validating the reliability of our analytical method. This method also enables us to measure the sulfur concentration simultaneously when analyzing the sulfur isotope composition. There is a strong linear correlation (R(2)>0.999) between the sulfur concentrations and the intensity ratios of samples and the standard. We have constructed a regression curve based on Alfa-S solutions and this curve has been successfully used to determine sulfur concentrations of AS solutions and pore water samples. The analytical technique presented here enable rapid, precise and accurate S isotope measurement for a wide range of sulfur-bearing solutions - in particular for pore water samples with complex matrix and varying sulfur concentrations. Also, simultaneous measurement of sulfur concentrations is available.

  1. Determination of uranium isotopes in environmental samples by anion exchange in sulfuric and hydrochloric acid media.

    PubMed

    Popov, L

    2016-09-01

    Method for determination of uranium isotopes in various environmental samples is presented. The major advantages of the method are the low cost of the analysis, high radiochemical yields and good decontamination factors from the matrix elements, natural and man-made radionuclides. The separation and purification of uranium is attained by adsorption with strong base anion exchange resin in sulfuric and hydrochloric acid media. Uranium is electrodeposited on a stainless steel disk and measured by alpha spectrometry. The analytical method has been applied for the determination of concentrations of uranium isotopes in mineral, spring and tap waters from Bulgaria. The analytical quality was checked by analyzing reference materials. PMID:27451111

  2. Determination of uranium isotopes in environmental samples by anion exchange in sulfuric and hydrochloric acid media.

    PubMed

    Popov, L

    2016-09-01

    Method for determination of uranium isotopes in various environmental samples is presented. The major advantages of the method are the low cost of the analysis, high radiochemical yields and good decontamination factors from the matrix elements, natural and man-made radionuclides. The separation and purification of uranium is attained by adsorption with strong base anion exchange resin in sulfuric and hydrochloric acid media. Uranium is electrodeposited on a stainless steel disk and measured by alpha spectrometry. The analytical method has been applied for the determination of concentrations of uranium isotopes in mineral, spring and tap waters from Bulgaria. The analytical quality was checked by analyzing reference materials.

  3. HIGH ARSENIC CONCENTRATIONS AND ENRICHED SULFUR AND OXYGEN ISOTOPES IN A FRACTURED-BEDROCK GROUND-WATER SYSTEM

    EPA Science Inventory

    Elevated arsenic concentrations are coincident with enriched sulfur and oxygen isotopes of sulfate in bedrock ground water within Kelly's Cove watershed, Northport, Maine, USA. Interpretation of the data is complicated by the lack of correlations between sulfate concentrations an...

  4. Carbon, nitrogen and sulfur in lunar fines 15012 and 15013 - Abundances, distributions and isotopic compositions

    NASA Technical Reports Server (NTRS)

    Chang, S.; Lawless, J.; Romiez, M.; Kaplan, I. R.; Petrowski, C.; Sakai, H.; Smith, J. W.

    1974-01-01

    Lunar fines 15012,16 and 15013,3 were analyzed by stepwise pyrolysis and acid hydrolysis as well as complete combustion in oxygen to determine carbon, nitrogen and sulfur. In addition, hydrogen was analysed during pyrolysis as well as during hydrolysis. By comparison of the distribution frequencies of C, N, S, H2 and Fe with He-4, considered to have arisen from solar wind contribution, it is concluded that nitrogen and hydrogen have largely a solar origin. Carbon has a significant solar contribution, and metallic iron may have resulted from solar wind interaction with ferrous minerals on the lunar surface. Sulfur probably has a predominantly lunar origin. There is no direct evidence for meteorotic contribution to these samples. Solar wind interaction also has a marked effect on the stable isotope distribution of C-13/C-12, N-15/N-14, and S-34/S-32. In all cases, the heavy isotope was most enriched in the smallest grain-size fraction.

  5. Isotopic Approaches to Allying Productivity and Sulfur Metabolism in Three Symbiotic Hydrothermal Vent Molluscs

    NASA Astrophysics Data System (ADS)

    Beinart, R.; Gartman, A.; Sanders, J. G.; Luther, G. W.; Girguis, P. R.

    2012-12-01

    Symbioses between animals and chemosynthetic bacteria predominate at hydrothermal vents. In these associations, the endosymbiotic bacteria utilize chemical reductants for the energy to support autotrophy, providing primary nutrition for the host. Despite their ubiquity at vents worldwide, little is known about the rates of productivity of these symbioses under different physico-chemical regimes or how their metabolism effects the local geochemical environment. To address this matter, we used high-pressure flow through incubations and stable isotopic tracers to maintain three genera of symbiotic mollusc - the gastropods Alviniconcha and Ifremeria, and the mussel Bathymodiolus - at vent-like conditions. Via the incorporation of isotopically labeled compounds, we assessed their productivity when using different reduced sulfur species as reductants. Using cyclic voltammetry, mass spectrometry and discrete geochemical analyses, we concurrently measured their effect on sulfur flux from the vessels. We found that the symbionts of all three genera can support autotrophy with hydrogen sulfide and thiosulfate, though at different rates. Additionally, by examining the rate of isotopic incorporation into biomass, we revealed intra-generic variability in productivity among the individuals in our experimental assemblages that are likely related to differences in the geochemical regime along the length of reactor. These geochemical gradients are due to the activity of other individuals within the vessel, since those organisms closest to the influent of the vent-like water had the highest measured carbon incorporation. Finally, we measured the uptake and excretion of sulfur species, which illustrate the degree to which these symbioses might impact local sulfur chemistry in situ. These experiments show that A) access to particular sulfur species differentially affects the productivity of vent symbioses, suggesting that competition for these substrates, both within and between host

  6. Antiquity and evolutionary status of bacterial sulfate reduction: sulfur isotope evidence.

    PubMed

    Schidlowski, M

    1979-09-01

    The presently available sedimentary sulfur isotope record for the Precambrian seems to allow the following conclusions: (1) In the Early Archaean, sedimentary delta 34S patterns attributable to bacteriogenic sulfate reduction are generally absent. In particular, the delta 34S spread observed in the Isua banded iron formation (3.7 x 10(9) yr) is extremely narrow and coincides completely with the respective spreads yielded by contemporaneous rocks of assumed mantle derivation. Incipient minor differentiation of the isotope pattersn notably of Archaean sulfates may be accounted for by photosynthetic sulfur bacteria rather than by sulfate reducers. (2) Isotopic evidence of dissimilatory sulfate reduction is first observed in the upper Archaean of the Aldan Shield, Siberia (approximately 3.0 x 10(9) yr) and in the Michipicoten and Woman River banded iron formations of Canada (2.75 x 10(9) yr). This narrows down the possible time of appearance of sulfate respirers to the interval 2.8--3.1 x 10(9) yr. (3) Various lines of evidence indicate that photosynthesis is older than sulfate respiration, the SO4(2-) Utilized by the first sulfate reducers deriving most probably from oxidation of reduced sulfur compounds by photosynthetic sulfur bacteria. Sulfate respiration must, in turn, have antedated oxygen respiration as O2-respiring multicellular eucaryotes appear late in the Precambrian. (4) With the bulk of sulfate in the Archaean oceans probably produced by photosynthetic sulfur bacteria, the accumulation of SO4(2-) in the ancient seas must have preceded the buildup of appreciable steady state levels of free oxygen. Hence, the occurrence of sulfate evaporites in Archaean sediments does not necessarily provide testimony of oxidation weathering on the ancient continents and, consequently, of the existence of an atmospheric oxygen reservoir.

  7. Antiquity and evolutionary status of bacterial sulfate reduction: sulfur isotope evidence.

    PubMed

    Schidlowski, M

    1979-09-01

    The presently available sedimentary sulfur isotope record for the Precambrian seems to allow the following conclusions: (1) In the Early Archaean, sedimentary delta 34S patterns attributable to bacteriogenic sulfate reduction are generally absent. In particular, the delta 34S spread observed in the Isua banded iron formation (3.7 x 10(9) yr) is extremely narrow and coincides completely with the respective spreads yielded by contemporaneous rocks of assumed mantle derivation. Incipient minor differentiation of the isotope pattersn notably of Archaean sulfates may be accounted for by photosynthetic sulfur bacteria rather than by sulfate reducers. (2) Isotopic evidence of dissimilatory sulfate reduction is first observed in the upper Archaean of the Aldan Shield, Siberia (approximately 3.0 x 10(9) yr) and in the Michipicoten and Woman River banded iron formations of Canada (2.75 x 10(9) yr). This narrows down the possible time of appearance of sulfate respirers to the interval 2.8--3.1 x 10(9) yr. (3) Various lines of evidence indicate that photosynthesis is older than sulfate respiration, the SO4(2-) Utilized by the first sulfate reducers deriving most probably from oxidation of reduced sulfur compounds by photosynthetic sulfur bacteria. Sulfate respiration must, in turn, have antedated oxygen respiration as O2-respiring multicellular eucaryotes appear late in the Precambrian. (4) With the bulk of sulfate in the Archaean oceans probably produced by photosynthetic sulfur bacteria, the accumulation of SO4(2-) in the ancient seas must have preceded the buildup of appreciable steady state levels of free oxygen. Hence, the occurrence of sulfate evaporites in Archaean sediments does not necessarily provide testimony of oxidation weathering on the ancient continents and, consequently, of the existence of an atmospheric oxygen reservoir. PMID:503456

  8. Stereospecific Multiple Isotopic Labeling of Benzyl Alcohol

    PubMed Central

    Roston, Daniel; Kohen, Amnon

    2015-01-01

    Isotopically labeled enzymatic substrates and biological metabolites are useful for many mechanistic analyses, particularly the study of kinetic and equilibrium isotope effects, determining the stereospecificity of enzymes, and resolving metabolic pathways. Here we present the 1-pot synthesis, purification, and kinetic analysis of 7R-[2H]-phenyl-[14C]-benzyl alcohol. The procedure involves a chemoenzymatic synthesis that couples formate dehydrogenase to alcohol dehydrogenase with a catalytic amount of nicotinamide cofactor. The reaction goes to completion overnight, and the measurement of a competitive kinetic isotope effect on the enzymatic oxidation of the purified product identified no 1H contamination. This measurement is very sensitive to such isotopic contamination and verified the high level of isotopic and enantiomeric purity yielded by the new synthetic procedure. PMID:24327376

  9. Biogeochemistry of sulfur in the Vienna Woods: Study of sulfur stable isotope ratios by MC-ICP-MS as indicator of biogeochemical S cycling

    NASA Astrophysics Data System (ADS)

    Hanousek, Ondrej; Berger, Torsten W.; Prohaska, Thomas

    2014-05-01

    Sulfur entering forest ecosystems originates mainly from combustion of fossil fuels. This source of sulfur has been strongly (by more than 95 %) reduced in last decades and recently, higher sulfur output (in soil solution or stream water) than sulfur input (in rain water) in an ecosystem was registered in many monitored forest ecosystems. This unbalance may be caused by weathering of sulfur-bearing rocks, desorption of sulfur adsorbed in soil in the past or (re)mineralization of organic sulfur compounds. This 'negative' balance leads to mobilization of base cations along with SO42- and as such to an acidification of soils. As hypothesis, δ34S/32S depletion in stream water will be observed if a considerable proportion of atmospherically deposited sulfate is cycled through the organic S pool. Rain water and soil solutions samples were collected for this study at 3 sites (beech stands) in the Vienna Woods, Austria twice a month from May 2010 to April 2012. Due to the expected sulfate concentration gradient with respect to the distance from a tree, sampling was carried out at 5 intervals from a stem. The sulfur concentration in the samples was determined by ion chromatography. Sulfur isotope ratios (δ34S/32SV CDT) were analyzed by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) in edge-resolution mode. The method was validated using IAEA-S-1 and IAEA-S-2 isotopic certified reference materials. The combined standard uncertainty of the measurement (uc = 0.10 %, k = 1) proves the suitability of the developed method. The concentration of sulfur in rain water showed expected behavior, with a seasonal maximum in winter months, in contrast to the corresponding δ34S/32SV CDT isotope ratios, where no or low seasonal trends were observed. The sulfur isotope ratios in soil solution samples show a dependence on the distance from a tree stem and the sampling depth with lower δ34S/32SV CDT ratios as compared to the precipitation. The measured isotopic

  10. Sulfur and oxygen isotope fractionation during sulfate reduction coupled to anaerobic oxidation of methane is dependent on methane concentration

    NASA Astrophysics Data System (ADS)

    Deusner, Christian; Holler, Thomas; Arnold, Gail L.; Bernasconi, Stefano M.; Formolo, Michael J.; Brunner, Benjamin

    2014-08-01

    Isotope signatures of sulfur compounds are key tools for studying sulfur cycling in the modern environment and throughout earth's history. However, for meaningful interpretations, the isotope effects of the processes involved must be known. Sulfate reduction coupled to the anaerobic oxidation of methane (AOM-SR) plays a pivotal role in sedimentary sulfur cycling and is the main process responsible for the consumption of methane in marine sediments - thereby efficiently limiting the escape of this potent greenhouse gas from the seabed to the overlying water column and atmosphere. In contrast to classical dissimilatory sulfate reduction (DSR), where sulfur and oxygen isotope effects have been measured in culture studies and a wide range of isotope effects has been observed, the sulfur and oxygen isotope effects by AOM-SR are unknown. This gap in knowledge severely hampers the interpretation of sulfur cycling in methane-bearing sediments, especially because, unlike DSR which is carried out by a single organism, AOM-SR is presumably catalyzed by consortia of archaea and bacteria that both contribute to the reduction of sulfate to sulfide. We studied sulfur and oxygen isotope effects by AOM-SR at various aqueous methane concentrations from 1.4±0.6 mM up to 58.8±10.5 mM in continuous incubation at steady state. Changes in the concentration of methane induced strong changes in sulfur isotope enrichment (εS34) and oxygen isotope exchange between water and sulfate relative to sulfate reduction (θO), as well as sulfate reduction rates (SRR). Smallest εS34 (21.9±1.9‰) and θO (0.5±0.2) as well as highest SRR were observed for the highest methane concentration, whereas highest εS34 (67.3±26.1‰) and θO (2.5±1.5) and lowest SRR were reached at low methane concentration. Our results show that εS34, θO and SRR during AOM-SR are very sensitive to methane concentration and thus also correlate with energy yield. In sulfate-methane transition zones, AOM-SR is likely

  11. Speciation and isotopic composition of sedimentary sulfur in the Everglades, Florida, USA

    USGS Publications Warehouse

    Bates, A.L.; Spiker, E. C.; Holmes, C.W.

    1998-01-01

    We have studied the sulfur speciation and isotopic composition of two peat cores from Water Conservation Area 2A (WCA 2A) in the Florida Everglades. Core site E1 is affected by agricultural runoff from the Hillsboro Canal which drains the Everglades Agricultural Area; Core site U3 is distant from the canal and relatively unaffected by agricultural runoff. Depth profiles of the total sulfur content of both cores show fairly constant levels (??0.7 wt.%) below about 25-30 cm depth in Core E1 and below 40-45 cm in Core U3. Above these depths, total sulfur increases to as much as 1.52 wt.% in Core E1 and 1.74 wt.% in Core U3, suggesting that more sulfur has entered the sediments and/or that more sulfur is being retained in recent times at both sampling sites. These changes in total sulfur content with depth in Core E1 correlate with changes in total phosphorus that have been observed in other studies at core sites near the Hillsboro Canal. This correlation of total sulfur with phosphorus with depth is not seen in Core U3 located away from the canal, possibly because phosphorus is more effectively retained than sulfur in the organic sediment near the canal. Organic-sulfur (OS) concentrations are at least twice as high as the dusulfide-sulfur (DS) concentrations in the upper parts of both cores suggesting that iron is presently limiting the amount of dusulfide minerals formed in these sediments. The degree of pyritization (DOP) in the upper parts of the cores suggest that sulfide mineralization is limited by the availability of highly reactive iron during the earliest stages of diagenesis. Positive ??34S values for reduced sulfur forms in both cores indicate a relatively restricted sulfate reservoir, consistent with nearly complete reduction of the sulfate available in the sediment at any given time. Differences between the two core appear in the ??34S values for the near-surface sediments. The DS ??34S values in the upper 10.0 cm of sediment are more posotive at site E1

  12. Sulfur

    USGS Publications Warehouse

    Apodaca, L.E.

    2012-01-01

    In 2011, elemental sulfur and the byproduct sulfuric acid were produced at 109 operations in 29 states and the U.S. Virgin Islands. Total shipments were valued at about $1.6 billion. Elemental sulfur production was 8.2 Mt (9 million st); Louisiana and Texas accounted for about 53 percent of domestic production.

  13. Sulfur Isotope Fractionation Due to SO2 Photolysis in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Lyons, J. R.; Blackie, D.; Stark, G.; Pickering, J.

    2012-12-01

    The discovery of unusual (i.e. mass-independent) sulfur isotope fractionation (or MIF) in Archean and Paleoproterozoic sedimentary rocks has promised to yield insights into the rise of O2 and the nature of the sulfur cycle on ancient Earth [1], but interpretation has been hampered by the lack of a clear mechanism for the sulfur isotope signature. Proposed MIF mechanisms include SO2 photolysis [1-4], atmospheric S3 (thiozone) formation, and thermal sulfate reduction in sediments [5]. Studies focusing only on SO2 photolysis, including measurements of isotopic cross sections [6], have yielded results differing greatly from theory [4], and have resulted in improbable interpretations [7]. In addition to ancient rocks, there are sulfur isotope MIF signatures in polar ice core sulfates associated with massive Plinian eruptions over the past ~1000 years (e.g., [8]). The ice core MIF signatures differ significantly from the ancient Earth MIF signatures, suggesting a different source mechanism. SO2 photolysis can generate sulfur isotope MIF signatures in two ways: 1) self-shielding by an optically-thick column of SO2, and 2) isotope-dependent differences in absorption line intensities and widths, which are espcially important for optically-thin conditions. The MIF signatures in ice core sulfates appear to be consistent with self-shielding in an optically-thick plume, but the Archean MIF clearly is not. To address the optically-thin case, we've made high-resolution ultraviolet cross section measurements of the sulfur isotopologues of SO2 made with the UV FTS at Imperial College. We measured cross sections at 1 cm-1 spectral resolution for 32SO2, 33SO2, 34SO2 and for a 36SO2/34SO2 mixture. Incorporating these cross sections into a simple atmospheric photochemical model with a solar UV flux, we find sulfur MIF signatures for SO and S that.are consistent with the Archean pyrites. We also find that additional mass-dependent fractionation during self-shielding by 32SO2 places an

  14. Sulfur and oxygen isotope geochemistry of acid mine drainage--the polymetallic sulfide deposit "himmelfahrt fundgrube" in Freiberg (Germany).

    PubMed

    Haubrich, F; Tichomirowa, M

    2002-06-01

    We investigated physical, chemical and isotope (S, O) parameters of sulfate from acid mine drainage from the polymetallic sulfide ore deposit Freiberg (Gennany), which was mined for more than eight hundred years. Two main groups of water were distinguished: 1. Flowing mine water with sulfate concentrations of less than 9,000 mg/l and pH values higher than 3.2, 2. Pore water in weathered low grade ores and pools with sulfate concentrations higher than 9000mg/l and pH values below 3.2. The sulfur and oxygen isotope composition of sulfate from flowing mine waters reflects mixing of sulfate from two sulfur sources: a) atmospheric sulfur from precipitation and b) sulfate formed as a result of sulfide oxidation processes. Sulfur isotope values of mine water sulfate were used to estimate the contribution of sulfate derived through oxidation of sulfides. The sulfur isotope composition of pore water sulfate and precipitated sulfate (jarosite) from weathered low grade ore samples is identical to the sulfur isotope composition of primary sulfides. The oxygen isotope composition of pore water sulfate from low grade ore samples indicates that the oxidation process proceeds relatively slowly in 02-depleted waters, probably without significant microbial catalysis. PMID:12219981

  15. Oxygen and sulfur isotope systematics of sulfate produced during abiotic and bacterial oxidation of sphalerite and elemental sulfur

    USGS Publications Warehouse

    Balci, N.; Mayer, B.; Shanks, Wayne C.; Mandernack, K.W.

    2012-01-01

    Studies of metal sulfide oxidation in acid mine drainage (AMD) systems have primarily focused on pyrite oxidation, although acid soluble sulfides (e.g., ZnS) are predominantly responsible for the release of toxic metals. We conducted a series of biological and abiotic laboratory oxidation experiments with pure and Fe-bearing sphalerite (ZnS & Zn 0.88Fe 0.12S), respectively, in order to better understand the effects of sulfide mineralogy and associated biogeochemical controls of oxidation on the resultant ?? 34S and ?? 18O values of the sulfate produced. The minerals were incubated in the presence and absence of Acidithiobacillus ferrooxidans at an initial solution pH of 3 and with water of varying ?? 18O values to determine the relative contributions of H 2O-derived and O 2-derived oxygen in the newly formed sulfate. Experiments were conducted under aerobic and anaerobic conditions using O 2 and Fe(III) aq as the oxidants, respectively. Aerobic incubations with A. ferrooxidans, and S o as the sole energy source were also conducted. The ??34SSO4 values from both the biological and abiotic oxidation of ZnS and ZnS Fe by Fe(III) aq produced sulfur isotope fractionations (??34SSO4-ZnS) of up to -2.6???, suggesting the accumulation of sulfur intermediates during incomplete oxidation of the sulfide. No significant sulfur isotope fractionation was observed from any of the aerobic experiments. Negative sulfur isotope enrichment factors (??34SSO4-ZnS) in AMD systems could reflect anaerobic, rather than aerobic pathways of oxidation. During the biological and abiotic oxidation of ZnS and ZnS Fe by Fe(III) aq all of the sulfate oxygen was derived from water, with measured ?? 18OSO 4-H 2O values of 8.2??0.2??? and 7.5??0.1???, respectively. Also, during the aerobic oxidation of ZnS Fe and S o by A. ferrooxidans, all of the sulfate oxygen was derived from water with similar measured ?? 18OSO 4-H 2O values of 8.1??0.1??? and 8.3??0.3???, respectively. During biological oxidation

  16. Sulfur isotope geochemistry of ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type ore district, Poland

    USGS Publications Warehouse

    Leach, D.L.; Vets, J.G.; Gent, C.A.

    1996-01-01

    Studies of the sulfur isotopic composition of ore and gangue minerals from the Silesian-Cracow Zn-Pb district were conducted to gain insights into processes that controlled the location and distribution of the ore deposits. Results of this study show that minerals from the Silesian-Cracow ore district have the largest range of sulfur isotope compositions in sulfides observed from any Mississippi Valley-type ore district in the world. The ??34S values for sulfide minerals range from +38 to -32 per mil for the entire paragenetic sequence but individual stages exhibit smaller ranges. There is a well developed correlation between the sulfur isotope composition and paragenetic stage of ore deposition. The first important ore stage contains mostly positive ??34S values, around 5 per mil. The second stage of ore formation are lower, with a median value of around -5 to -15 per mil, and with some values as low as -32 per mil. Late stage barite contains isotopically heavy sulfur around +32 per mil. The range in sulfur isotope compositions can be explained by contributions of sulfur from a variety of source rocks together with sulfur isotope fractionations produced by the reaction paths for sulfate reduction. Much of the variation in sulfur isotope compositions can be explained by bacterial reduction of sedimentary sulfate and disequilibrium reactions by intermediate-valency sulfur species, especially in the late-stage pyrite and sphalerite. Organic reduction of sulfate and thermal release of sulfur from coals in the Upper Silesian Coal Basin may have been important contributors to sulfur in the ore minerals. The sulfur isotopic data, ore mineral textures, and fluid inclusion data, are consistent with the hypothesis that fluid mixing was the dominant ore forming mechanism. The rather distinct lowering of ?? 34S values in sulfides from stage 2 to stage 3 is believed to reflect some fundamental change in the source of reduced sulfur and/or hydrology of the ore

  17. Sulfur, carbon, hydrogen, and oxygen isotope geochemistry of the Idaho cobalt belt

    USGS Publications Warehouse

    Johnson, Craig A.; Bookstrom, Arthur A.; Slack, John F.

    2012-01-01

    Cobalt-copper ± gold deposits of the Idaho cobalt belt, including the deposits of the Blackbird district, have been analyzed for their sulfur, carbon, hydrogen, and oxygen isotope compositions to improve the understanding of ore formation. Previous genetic hypotheses have ranged widely, linking the ores to the sedimentary or diagenetic history of the host Mesoproterozoic sedimentary rocks, to Mesoproterozoic or Cretaceous magmatism, or to metamorphic shearing. The δ34S values are nearly uniform throughout the Blackbird dis- trict, with a mean value for cobaltite (CoAsS, the main cobalt mineral) of 8.0 ± 0.4‰ (n = 19). The data suggest that (1) sulfur was derived at least partly from sedimentary sources, (2) redox reactions involving sulfur were probably unimportant for ore deposition, and (3) the sulfur was probably transported to sites of ore for- mation as H2S. Hydrogen and oxygen isotope compositions of the ore-forming fluid, which are calculated from analyses of biotite-rich wall rocks and tourmaline, do not uniquely identify the source of the fluid; plausible sources include formation waters, metamorphic waters, and mixtures of magmatic and isotopically heavy meteoric waters. The calculated compositions are a poor match for the modified seawaters that form vol- canogenic massive sulfide (VMS) deposits. Carbon and oxygen isotope compositions of siderite, a mineral that is widespread, although sparse, at Blackbird, suggest formation from mixtures of sedimentary organic carbon and magmatic-metamorphic carbon. The isotopic compositions of calcite in alkaline dike rocks of uncertain age are consistent with a magmatic origin. Several lines of evidence suggest that siderite postdated the emplacement of cobalt and copper, so its significance for the ore-forming event is uncertain. From the stable isotope perspective, the mineral deposits of the Idaho cobalt belt contrast with typical VMS and sedimentary exhalative deposits. They show characteristics of deposit

  18. Study of thermochemical sulfate reduction mechanism using compound specific sulfur isotope analysis

    NASA Astrophysics Data System (ADS)

    Meshoulam, Alexander; Ellis, Geoffrey S.; Said Ahmad, Ward; Deev, Andrei; Sessions, Alex L.; Tang, Yongchun; Adkins, Jess F.; Liu, Jinzhong; Gilhooly, William P.; Aizenshtat, Zeev; Amrani, Alon

    2016-09-01

    The sulfur isotopic fractionation associated with the formation of organic sulfur compounds (OSCs) during thermochemical sulfate reduction (TSR) was studied using gold-tube pyrolysis experiments to simulate TSR. The reactants used included n-hexadecane (n-C16) as a model organic compound with sulfate, sulfite, or elemental sulfur as the sulfur source. At the end of each experiment, the S-isotopic composition and concentration of remaining sulfate, H2S, benzothiophene, dibenzothiophene, and 2-phenylthiophene (PT) were measured. The observed S-isotopic fractionations between sulfate and BT, DBT, and H2S in experimental simulations of TSR correlate well with a multi-stage model of the overall TSR process. Large kinetic isotope fractionations occur during the first, uncatalyzed stage of TSR, 12.4‰ for H2S and as much as 22.2‰ for BT. The fractionations decrease as the H2S concentration increases and the reaction enters the second, catalyzed stage. Once all of the oxidizable hydrocarbons have been consumed, sulfate reduction ceases and equilibrium partitioning then dictates the fractionation between H2S and sulfate (∼17‰). Experiments involving sparingly soluble CaSO4 show that during the second catalytic phase of TSR the rate of sulfate reduction exceeds that of sulfate dissolution. In this case, there is no apparent isotopic fractionation between source sulfate and generated H2S, as all of the available sulfate is effectively reduced at all reaction times. When CaSO4 is replaced with fully soluble Na2SO4, sulfate dissolution is no longer rate limiting and significant S-isotopic fractionation is observed. This supports the notion that CaSO4 dissolution can lead to the apparent lack of fractionation between H2S and sulfate produced by TSR in nature. The S-isotopic composition of individual OSCs record information related to geochemical reactions that cannot be discerned from the δ34S values obtained from bulk phases such as H2S, oil, and sulfate minerals, and

  19. Sulfur isotopic variations during subduction of hydrated lithosphere: the Erro Tobbio case

    NASA Astrophysics Data System (ADS)

    Santiago Ramos, D.; Shimizu, N.; Scambelluri, M.

    2012-12-01

    High-pressure serpentinites provide unique opportunities for advancing our understanding of geochemical changes in hydrated lithosphere during subduction, and deep recycling of elements. The Erro Tobbio serpentinized peridotites range from hydrated Jurassic oceanic lithosphere to those recrystallized at ~550°C 2 - 2.5 GPa during Alpine subduction (Scambelluri et al., 2001), and are shown to possess boron signatures indicating addition and retention of seawater-derived boron up to the highest pressure-temperature conditions recorded (Scambelluri and Tonarini, 2012). We conducted in-situ sulfur isotope analysis of individual sulfide grains (pentlandite and heazlewoodite) in samples representing early low-temperature serpentinization and those in serpentinized peridotites and serpentinites recrystallized at high pressures and temperatures, using the Cameca IMS 1280 at Woods Hole Oceanographic Institution. Instrumental mass fractionation was shown to be identical for pyrrhotite and pentlandite, indicating that Fe/Ni ratios do not bias observed sulfur isotopic compositions. A pyrrhotite standard with known δ34S was mounted in an indium substrate together with polished pieces of rock specimens with sulfide grains, and analyses of unknowns were bracketed by repeated analyses of the standard. A primary ion beam of 133Cs+ with a current of ~10 pA was focused to a spot of <5μm in diameter for analysis of micron-size grains. Internal and external precisions generally range from 0.4‰ to 0.7‰ (2σ standard error). Salient features of the results include: (1) pentlandites in low-temperature "early serpentinites" are light in δ34S, ranging from -3.2 - -0.4‰ in one sample to +0.7 - +5.9‰ in another; (2) two mylonitic high-pressure serpentinites are heavy in δ34S, with +9.8 - +11.1‰ in one sample and +8.8 - +11.6‰ in another; (3) an undeformed high pressure serpentinized peridotite shows a bimodal isotopic compositions with -1.1 - +0.5‰ in one group of grains and

  20. Evidence for deep sea hydrothermal fluid-mineral equilibrium from multiple S isotopes

    NASA Astrophysics Data System (ADS)

    McDermott, J. M.; Ono, S.; Tivey, M. K.; Seewald, J.

    2010-12-01

    The multiple sulfur isotope systematics of hydrothermal fluids and associated sulfide mineral deposits collected in 2006 in the eastern Manus Basin, Papua New Guinea, provide an opportunity to better understand the processes of mineral precipitation, pore fluid composition, chemosynthetic energy sources, and metal-rich ore deposition in a felsic-hosted back arc hydrothermal system. Recent advances in multiple-stable isotope analytical techniques now enable the precise determination of all four stable isotopes of sulfur in hydrothermal vent fluids and co-precipitated sulfide mineral deposits, which may be used as a tracer to distinguish between sulfide derived from igneous rock, microbial sulfate reduction, and thermochemical reduction of seawater sulfate [1]. Multiple-stable isotopes of sulfur may also help constrain the relative contribution of sulfur derived by degassing of magmatic SO2 and sedimentary sulfide mineral inputs, as either process could generate the isotopically light δ34S (< 0‰) observed in some vent fluids, chalcopyrite chimney linings, and native sulfur collected at Manus Basin. We have analyzed the sulfur isotopic composition of high temperature black smoker vent fluid and associated chalcopyrite lining the inner walls of active conduits from two vent fields within the Manus Basin, including PACMANUS, located on the neovolcanic Pual ridge, and vents on discrete volcanic domes at SuSu Knolls. Preliminary results yield vent fluid δ34SH2S values ranging from -4.89 ± 0.02 to 5.41 ± 0.01, which closely match coexisting inner wall δ34Schalcopyrite values, ranging from -4.43 ± 0.01 to 5.64 ± 0.01. These results contrast with previous studies that report systematic differences in vent fluid δ34SH2S and sulfide minerals from the inner conduits of chimney structures [1, 2, 3]. The Δ33SH2S values of vent fluids range from -0.031 ± 0.027 to 0.011 ± 0.016, and those of chalcopyrite range from -0.042 ± 0.012 to 0.012 ± 0.010. Preliminary results

  1. Sulfur-based absolute quantification of proteins using isotope dilution inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Lee, Hyun-Seok; Heun Kim, Sook; Jeong, Ji-Seon; Lee, Yong-Moon; Yim, Yong-Hyeon

    2015-10-01

    An element-based reductive approach provides an effective means of realizing International System of Units (SI) traceability for high-purity biological standards. Here, we develop an absolute protein quantification method using double isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS) combined with microwave-assisted acid digestion for the first time. We validated the method and applied it to certify the candidate protein certified reference material (CRM) of human growth hormone (hGH). The concentration of hGH was determined by analysing the total amount of sulfur in hGH. Next, the size-exclusion chromatography method was used with ICP-MS to characterize and quantify sulfur-containing impurities. By subtracting the contribution of sulfur-containing impurities from the total sulfur content in the hGH CRM, we obtained a SI-traceable certification value. The quantification result obtained with the present method based on sulfur analysis was in excellent agreement with the result determined via a well-established protein quantification method based on amino acid analysis using conventional acid hydrolysis combined with an ID liquid chromatography-tandem mass spectrometry. The element-based protein quantification method developed here can be generally used for SI-traceable absolute quantification of proteins, especially pure-protein standards.

  2. Chemical weathering and the role of sulfuric and nitric acids in carbonate weathering: Isotopes (13C, 15N, 34S, and 18O) and chemical constraints

    NASA Astrophysics Data System (ADS)

    Li, Cai; Ji, Hongbing

    2016-05-01

    Multiple isotopes (13C-DIC, 34S and 18O-SO42-, 15N and 18O-NO3-) and water chemistry were used to evaluate weathering rates and associated CO2 consumption by carbonic acid and strong acids (H2SO4 and HNO3) in a typical karst watershed (Wujiang River, Southwest China). The dual sulfate isotopes indicate that sulfate is mainly derived from sulfide oxidation in coal stratum and sulfide-containing minerals, and dual nitrate isotopes indicate that nitrate is mainly derived from soil N and nitrification. The correlation between isotopic compositions and water chemistry suggests that sulfuric and nitric acids, in addition to carbonic acid, are involved in carbonate weathering. The silicate and carbonate weathering rates are 7.2 t km-2 yr-1 and 76 t km-2 yr-1, respectively. In comparison with carbonate weathering rates (43 t km-2 yr-1) by carbonic acid alone, the subsequent increase in rates indicates significant enhancement of weathering when combined with sulfuric and nitric acids. Therefore, the role of sulfuric and nitric acids in the rock weathering should be considered in the global carbon cycle.

  3. Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets

    PubMed Central

    Antonelli, Michael A.; Kim, Sang-Tae; Peters, Marc; Labidi, Jabrane; Cartigny, Pierre; Walker, Richard J.; Lyons, James R.; Hoek, Joost; Farquhar, James

    2014-01-01

    Achondrite meteorites have anomalous enrichments in 33S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying 33S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the 33S anomalies, or of the bulk solar system S-isotope composition. Here, we report well-resolved anomalous 33S depletions in IIIF iron meteorites (<−0.02 per mil), and 33S enrichments in other magmatic iron meteorite groups. The 33S depletions support the idea that differentiated planetesimals inherited sulfur that was photochemically derived from gases in the early inner solar system (<∼2 AU), and that bulk inner solar system S-isotope composition was chondritic (consistent with IAB iron meteorites, Earth, Moon, and Mars). The range of mass-independent sulfur isotope compositions may reflect spatial or temporal changes influenced by photochemical processes. A tentative correlation between S isotopes and Hf-W core segregation ages suggests that the two systems may be influenced by common factors, such as nebular location and volatile content. PMID:25453079

  4. Oxygen and sulfur isotope fractionation during methane dependent sulfate reduction in high pressure continuous incubation studies

    NASA Astrophysics Data System (ADS)

    Deusner, C.; Brunner, B.; Holler, T.; Widdel, F.; Ferdelman, T. G.

    2009-12-01

    The anaerobic oxidation of methane (AOM) coupled to sulfate reduction in marine sediments is an important sink in the global methane budget. However, many aspects of methane dependent sulfate reduction are not fully understood. We developed a novel high pressure biotechnical system to simulate marine conditions with high concentrations of dissolved gases, e.g. at gas seeps and gas hydrate systems. The system allows for batch, fed-batch and continuous gas-phase free incubation. We employ this system to study the kinetics and isotope fractionation during AOM at varying methane partial pressures up to 10 MPa. We present the results of long-term continuous and fed-batch incubations with highly active naturally enriched biomass from microbial mats from the Black Sea. During these experiments the methane partial pressure was increased stepwise from 0.1 to 10 MPa. The methane dependent sulfate reduction rate increased from 0.1 mmol/l/d to 3.5 mmol/l/d resulting from the increase in methane concentration and microbial growth. Sulfate reduction was negligible in the absence of methane. The sulfur and oxygen isotope fractionation during sulfate reduction was strongly influenced by the concentration of dissolved methane. Sulfur isotope fractionation was highest at low methane concentrations, and lowest at high methane concentrations. Relative to sulfate reduction rates, oxygen isotope exchange between sulfate and water was highest at low methane concentrations, and lowest at high methane concentrations.

  5. Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets.

    PubMed

    Antonelli, Michael A; Kim, Sang-Tae; Peters, Marc; Labidi, Jabrane; Cartigny, Pierre; Walker, Richard J; Lyons, James R; Hoek, Joost; Farquhar, James

    2014-12-16

    Achondrite meteorites have anomalous enrichments in (33)S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying (33)S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the (33)S anomalies, or of the bulk solar system S-isotope composition. Here, we report well-resolved anomalous (33)S depletions in IIIF iron meteorites (<-0.02 per mil), and (33)S enrichments in other magmatic iron meteorite groups. The (33)S depletions support the idea that differentiated planetesimals inherited sulfur that was photochemically derived from gases in the early inner solar system (<∼2 AU), and that bulk inner solar system S-isotope composition was chondritic (consistent with IAB iron meteorites, Earth, Moon, and Mars). The range of mass-independent sulfur isotope compositions may reflect spatial or temporal changes influenced by photochemical processes. A tentative correlation between S isotopes and Hf-W core segregation ages suggests that the two systems may be influenced by common factors, such as nebular location and volatile content. PMID:25453079

  6. Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets.

    PubMed

    Antonelli, Michael A; Kim, Sang-Tae; Peters, Marc; Labidi, Jabrane; Cartigny, Pierre; Walker, Richard J; Lyons, James R; Hoek, Joost; Farquhar, James

    2014-12-16

    Achondrite meteorites have anomalous enrichments in (33)S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying (33)S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the (33)S anomalies, or of the bulk solar system S-isotope composition. Here, we report well-resolved anomalous (33)S depletions in IIIF iron meteorites (<-0.02 per mil), and (33)S enrichments in other magmatic iron meteorite groups. The (33)S depletions support the idea that differentiated planetesimals inherited sulfur that was photochemically derived from gases in the early inner solar system (<∼2 AU), and that bulk inner solar system S-isotope composition was chondritic (consistent with IAB iron meteorites, Earth, Moon, and Mars). The range of mass-independent sulfur isotope compositions may reflect spatial or temporal changes influenced by photochemical processes. A tentative correlation between S isotopes and Hf-W core segregation ages suggests that the two systems may be influenced by common factors, such as nebular location and volatile content.

  7. Coupled Iron and Sulfur Isotope Constraints on the Archean and Paleoproterozoic Ocean Redox State

    NASA Astrophysics Data System (ADS)

    Rouxel, O. J.; Bekker, A.

    2009-05-01

    The rise of atmospheric oxygen level by ca. 2.3 Ga have led to dramatic shifts in the iron and sulfur oceanic cycles. Past studies of non-mass dependent and mass dependent sulfur isotope record in sedimentary sulfides over geological time have placed important constraints on biogeochemical cycle of sulfur and evolution of Precambrian ocean chemistry. Recently, we applied a similar time-record approach to explore potential changes in Fe isotope composition of pyrite in black shales. Although the underlying mechanisms for Fe isotope fractionation in organic-rich sediments are debated, we identified direct link between the rise of atmospheric oxygen and changes in the Fe ocean cycle suggesting that Fe isotopes are useful proxies to the past ocean redox state. Since biogeochemical cycles of Fe and S are closely coupled in marine systems, Fe-limitation and S-limitation for pyrite formation in black shales should leave imprint on the isotopic record of both elements. Coupled Fe and S isotope systematics of Devonian pyrite display a range of 50‰ in δ34S values whereas δ56Fe values vary between - 1.0 and +0.1‰ consistent with Fe isotope variations in modern marine sediments. Similarly, pyrite in the 1.88 Ga Gunflint Formation has δ34S values ranging from - 32‰ to +10‰ and displays a range of δ56Fe values between 0 to - 0.4‰. In contrast, Archean black shales (e.g. Manjeri Fm., Belingwe Belt and Jeerinah Fm., Hamersley Basin) display a smaller range of δ34S values between together with ubiquitous non-mass dependent S-isotope fractionation but a larger range of δ56Fe values from - 3.5 to +0.2‰. A transitional period between ca. 2.3 and ca. 1.8 Ga is marked by a larger spread of δ34S values from - 34 to +28‰, disappearance of MIF and a larger range of δ56Fe values from - 1.7 to +1.1‰. These results confirm that after the rise of atmospheric oxygen by ca. 2.3 Ga, Paleoproterozoic ocean became stratified and gradually affected by an increase of seawater

  8. Isotope Biogeochemistry of Sulfur in a Cold-Water Carbonate Mound (IODP Site 1317)

    NASA Astrophysics Data System (ADS)

    Ferdelman, T. G.; Boettcher, M. E.

    2007-12-01

    To establish a depositional model for cold-water carbonate mounds, Challenger Mound and adjacent continental slope sites were drilled during IODP Expedition 307 in May 2005. Although a role for methane seepage and subsequent anaerobic oxidation was discounted both as a hard-round substrate for mound initiation and as a principal source of carbonate within the mound succession, interstitial water profiles of sulfate, alkalinity, Mg, and Sr indicated a tight coupling between carbonate diagenesis and mircrobial sulfate reduction. The reaction of sulfide with siliciclastic iron-bearing minerals to form pyrite was proposed to account for enhanced diagenetic carbonate precipitation (Ferdelman et al., 2006; Proc. IODP, vol. 307; doi:10.2204/iodp.proc.307.2006). To characterize these geomicrobial sulfur transformations in the carbonate mound sediments, the inorganic and stable isotope geochemical compositions of pore water sulfate and solid phase reduced sulfur compounds were performed. Acid-volatile sulfur (AVS) and pyrite del 34S compositions were usually similar and exhibited an increasing trend of from -40 per mil near surface to -20 per mil at the mound base at 132 mbsf. However, several excursions to more 34S sulfur enriched pyrite to values >0 per mil were observed in the deeper sections of the mound sequence. These excursions may be linked transitory changes in the depth of the methane-sulfate transition zone during mound build-up. The oxygen isotopic composition of residual dissolved sulfate indicates intracellular isotope exchange processes within the cells of SRBs, leading to increasing equilibration between extracellular pore water and sulfate.

  9. Stable Isotope Phenotyping via Cluster Analysis of NanoSIMS Data As a Method for Characterizing Distinct Microbial Ecophysiologies and Sulfur-Cycling in the Environment.

    PubMed

    Dawson, Katherine S; Scheller, Silvan; Dillon, Jesse G; Orphan, Victoria J

    2016-01-01

    Stable isotope probing (SIP) is a valuable tool for gaining insights into ecophysiology and biogeochemical cycling of environmental microbial communities by tracking isotopically labeled compounds into cellular macromolecules as well as into byproducts of respiration. SIP, in conjunction with nanoscale secondary ion mass spectrometry (NanoSIMS), allows for the visualization of isotope incorporation at the single cell level. In this manner, both active cells within a diverse population as well as heterogeneity in metabolism within a homogeneous population can be observed. The ecophysiological implications of these single cell stable isotope measurements are often limited to the taxonomic resolution of paired fluorescence in situ hybridization (FISH) microscopy. Here we introduce a taxonomy-independent method using multi-isotope SIP and NanoSIMS for identifying and grouping phenotypically similar microbial cells by their chemical and isotopic fingerprint. This method was applied to SIP experiments in a sulfur-cycling biofilm collected from sulfidic intertidal vents amended with (13)C-acetate, (15)N-ammonium, and (33)S-sulfate. Using a cluster analysis technique based on fuzzy c-means to group cells according to their isotope ((13)C/(12)C, (15)N/(14)N, and (33)S/(32)S) and elemental ratio (C/CN and S/CN) profiles, our analysis partitioned ~2200 cellular regions of interest (ROIs) into five distinct groups. These isotope phenotype groupings are reflective of the variation in labeled substrate uptake by cells in a multispecies metabolic network dominated by Gamma- and Deltaproteobacteria. Populations independently grouped by isotope phenotype were subsequently compared with paired FISH data, demonstrating a single coherent deltaproteobacterial cluster and multiple gammaproteobacterial groups, highlighting the distinct ecophysiologies of spatially-associated microbes within the sulfur-cycling biofilm from White Point Beach, CA.

  10. Stable Isotope Phenotyping via Cluster Analysis of NanoSIMS Data As a Method for Characterizing Distinct Microbial Ecophysiologies and Sulfur-Cycling in the Environment

    PubMed Central

    Dawson, Katherine S.; Scheller, Silvan; Dillon, Jesse G.; Orphan, Victoria J.

    2016-01-01

    Stable isotope probing (SIP) is a valuable tool for gaining insights into ecophysiology and biogeochemical cycling of environmental microbial communities by tracking isotopically labeled compounds into cellular macromolecules as well as into byproducts of respiration. SIP, in conjunction with nanoscale secondary ion mass spectrometry (NanoSIMS), allows for the visualization of isotope incorporation at the single cell level. In this manner, both active cells within a diverse population as well as heterogeneity in metabolism within a homogeneous population can be observed. The ecophysiological implications of these single cell stable isotope measurements are often limited to the taxonomic resolution of paired fluorescence in situ hybridization (FISH) microscopy. Here we introduce a taxonomy-independent method using multi-isotope SIP and NanoSIMS for identifying and grouping phenotypically similar microbial cells by their chemical and isotopic fingerprint. This method was applied to SIP experiments in a sulfur-cycling biofilm collected from sulfidic intertidal vents amended with 13C-acetate, 15N-ammonium, and 33S-sulfate. Using a cluster analysis technique based on fuzzy c-means to group cells according to their isotope (13C/12C, 15N/14N, and 33S/32S) and elemental ratio (C/CN and S/CN) profiles, our analysis partitioned ~2200 cellular regions of interest (ROIs) into five distinct groups. These isotope phenotype groupings are reflective of the variation in labeled substrate uptake by cells in a multispecies metabolic network dominated by Gamma- and Deltaproteobacteria. Populations independently grouped by isotope phenotype were subsequently compared with paired FISH data, demonstrating a single coherent deltaproteobacterial cluster and multiple gammaproteobacterial groups, highlighting the distinct ecophysiologies of spatially-associated microbes within the sulfur-cycling biofilm from White Point Beach, CA. PMID:27303371

  11. Stable Isotope Phenotyping via Cluster Analysis of NanoSIMS Data As a Method for Characterizing Distinct Microbial Ecophysiologies and Sulfur-Cycling in the Environment.

    PubMed

    Dawson, Katherine S; Scheller, Silvan; Dillon, Jesse G; Orphan, Victoria J

    2016-01-01

    Stable isotope probing (SIP) is a valuable tool for gaining insights into ecophysiology and biogeochemical cycling of environmental microbial communities by tracking isotopically labeled compounds into cellular macromolecules as well as into byproducts of respiration. SIP, in conjunction with nanoscale secondary ion mass spectrometry (NanoSIMS), allows for the visualization of isotope incorporation at the single cell level. In this manner, both active cells within a diverse population as well as heterogeneity in metabolism within a homogeneous population can be observed. The ecophysiological implications of these single cell stable isotope measurements are often limited to the taxonomic resolution of paired fluorescence in situ hybridization (FISH) microscopy. Here we introduce a taxonomy-independent method using multi-isotope SIP and NanoSIMS for identifying and grouping phenotypically similar microbial cells by their chemical and isotopic fingerprint. This method was applied to SIP experiments in a sulfur-cycling biofilm collected from sulfidic intertidal vents amended with (13)C-acetate, (15)N-ammonium, and (33)S-sulfate. Using a cluster analysis technique based on fuzzy c-means to group cells according to their isotope ((13)C/(12)C, (15)N/(14)N, and (33)S/(32)S) and elemental ratio (C/CN and S/CN) profiles, our analysis partitioned ~2200 cellular regions of interest (ROIs) into five distinct groups. These isotope phenotype groupings are reflective of the variation in labeled substrate uptake by cells in a multispecies metabolic network dominated by Gamma- and Deltaproteobacteria. Populations independently grouped by isotope phenotype were subsequently compared with paired FISH data, demonstrating a single coherent deltaproteobacterial cluster and multiple gammaproteobacterial groups, highlighting the distinct ecophysiologies of spatially-associated microbes within the sulfur-cycling biofilm from White Point Beach, CA. PMID:27303371

  12. Trace sulfate in mid-Proterozoic carbonates and the sulfur isotope record of biospheric evolution

    NASA Astrophysics Data System (ADS)

    Gellatly, Anne M.; Lyons, Timothy W.

    2005-08-01

    Concentrations of oceanic and atmospheric oxygen have varied over geologic time as a function of sulfur and carbon cycling at or near the Earth's surface. This balance is expressed in the sulfur isotope composition of seawater sulfate. Given the near absence of gypsum in pre-Phanerozoic sediments, trace amounts of carbonate-associated sulfate (CAS) within limestones or dolostones provide the best available constraints on the isotopic composition of sulfate in Precambrian seawater. Although absolute CAS concentrations, which range from those below detection to ˜120 ppm sulfate in this study, may be compromised by diagenesis, the sulfur isotope compositions can be buffered sufficiently to retain primary values. Stratigraphically controlled δ 34S measurements for CAS from three mid-Proterozoic carbonate successions (˜1.2 Ga Mescal Limestone, Apache Group, Arizona, USA; ˜1.45-1.47 Ga Helena and Newland formations, Belt Supergroup, Montana, USA; and ˜1.65 Ga Paradise Creek Formation, McNamara Group, NW Queensland, Australia) show large isotopic variability (+9.1‰ to +18.9‰, -1.1‰ to +27.3‰, and +14.1‰ to +37.3‰, respectively) over stratigraphic intervals of ˜50 to 450 m. This rapid variability, ranging from scattered to highly systematic, and overall low CAS abundances can be linked to sulfate concentrations in the mid-Proterozoic ocean that were substantially lower than those of the Phanerozoic but higher than values inferred for the Archean. Results from the Belt Supergroup specifically corroborate previous arguments for seawater contributions to the basin. Limited sulfate availability that tracks the oxygenation history of the early atmosphere is also consistent with the possibility of extensive deep-ocean sulfate reduction, the scarcity of bedded gypsum, and the stratigraphic δ 34S trends and 34S enrichments commonly observed for iron sulfides of mid-Proterozoic age.

  13. Sulfur isotope fractionation during bacterial sulfate reduction in organic-rich sediments

    NASA Astrophysics Data System (ADS)

    Habicht, Kirsten S.; Canfield, Donald E.

    1997-12-01

    Isotope fractionation during sulfate reduction by natural populations of sulfate-reducing bacteria was investigated in the cyanobacterial microbial mats of Solar Lake, Sinai and the sediments of Løgten Lagoon sulfuretum, Denmark. Fractionation was measured at different sediment depths, sulfate concentrations, and incubation temperatures. Rates of sulfate reduction varied between 0.1 and 37 μmol cm -3d -1, with the highest rates among the highest ever reported from natural sediments. The depletion of 34S during dissimilatory sulfate reduction ranged from 16%. to 42%., with the largest 34S-depletions associated with the lowest rates of sulfate reduction and the lowest 34S-depletions with the highest rates. However, at high sulfate reduction rates (>10 μmol cm -3d -1)the lowest fractionation was 20%. independent of the rates. Overall, there was a similarity between the fractionation obtained by the natural populations of sulfate reducers and previous measurements from pure cultures. This was somewhat surprising given the extremely high rates of sulfate reduction in the experiments. Our results are explained if we conclude that the fractionation was mainly controlled by the specific rate of sulfate reduction (mass cell -1 time -1) and not by the absolute rate (mass volume -1 time -1). Sedimentary sulfides (mainly FeS 2) were on average 40%. depleted in 34S compared to seawater sulfate. This amount of depletion was more than could be explained by the isotopic fractionations that we measured during bacterial sulfate reduction. Therefore, additional processes contributing to the fractionation of sulfur isotopes in the sediments are indicated. From both Solar Lake and Løgten Lagoon we were able to enrich cultures of elemental sulfur-disproportionating bacteria. We suggest that isotope fractionation accompanying elemental sulfur disproportionation contributes to the 34S depletion of sedimentary sulfides at our study sites.

  14. Oxygen and sulfur isotope fractionation during sulfide oxidation by anoxygenic phototrophic bacteria

    NASA Astrophysics Data System (ADS)

    Brabec, Michelle Y.; Lyons, Timothy W.; Mandernack, Kevin W.

    2012-04-01

    Sulfide-mediated anoxygenic photosynthesis (SMAP) carried out by anaerobic phototrophic bacteria may have played an important role in sulfur cycling, formation of sulfate, and, perhaps, primary production in the Earth’s early oceans. Determination of ε34SSO4-Sulfide- and ε18OSO4-H2O values for bacterial sulfide oxidation will permit more refined interpretation of the δ34S and δ18OSO4 values measured in modern anoxic environments, such as meromictic lakes where sulfide commonly extends into the photic zone, and in the ancient rock record, particularly during periods of the Precambrian when anoxic and sulfidic (euxinic) conditions were believed to be more pervasive than today. Laboratory experiments with anaerobic purple and green sulfur phototrophs, Allochromatium vinosum and Chlorobaculum tepidum, respectively, were conducted to determine the sulfur and oxygen isotope fractionation during the oxidation of sulfide to sulfate. Replicate experiments were conducted at 25 °C for A. vinosum and 45 °C for C. tepidum, and in duplicate at three different starting oxygen isotope values for water to determine sulfate-water oxygen isotope fractionations accurately (ε18OSO4-H2O). ε18OSO4-H2O values of 5.6 ± 0.2‰ and 5.4 ± 0.1‰ were obtained for A. vinosum and C. tepidum, respectively. Temperature had no apparent effect on the ε18OSO4-H2O values. By combining all data from both cultures, an average ε18OSO4-H2O value of 5.6 ± 0.3‰ was obtained for SMAP. This value falls between those previously reported for bacterial oxidation of sphalerite and elemental sulfur (7-9‰) and abiotic and biotic oxidation of pyrite and chalcopyrite (2-4‰). Sulfur isotope fractionation between sulfide and sulfate formed by A.vinosum was negligible (0.1 ± 0.2‰) during all experiments. For C. tepidum an apparent fractionation of -2.3 ± 0.5‰ was observed during the earlier stages of oxidation based on bulk δ34S measurements of sulfate and sulfide and became smaller (-0.7

  15. Sulfur isotopic evidence for sources of volatiles in Siberian Traps magmas

    NASA Astrophysics Data System (ADS)

    Black, Benjamin A.; Hauri, Erik H.; Elkins-Tanton, Linda T.; Brown, Stephanie M.

    2014-05-01

    The Siberian Traps flood basalts transferred a large mass of volatiles from the Earth's mantle and crust to the atmosphere. The eruption of the large igneous province temporally overlapped with the end-Permian mass extinction. Constraints on the sources of Siberian Traps volatiles are critical for determining the overall volatile budget, the role of crustal assimilation, the genesis of Noril'sk ore deposits, and the environmental effects of magmatism. We measure sulfur isotopic ratios ranging from -10.8‰ to +25.3‰ Vienna Cañon Diablo Troilite (V-CDT) in melt inclusions from Siberian Traps basaltic rocks. Our measurements, which offer a snapshot of sulfur cycling far from mid-ocean ridge and arc settings, suggest the δ34S of the Siberian Traps mantle melt source was close to that of mid-ocean ridge basalts. In conjunction with previously published whole rock measurements from Noril'sk, our sulfur isotopic data indicate that crustal contamination was widespread and heterogeneous—though not universal—during the emplacement of the Siberian Traps. Incorporation of crustal materials likely increased the total volatile budget of the large igneous province, thereby contributing to Permian-Triassic environmental deterioration.

  16. Effect of variable hydrothermal conditions on sulfur speciation and isotopic compositions mediated by two Thiomicrospira strains

    NASA Astrophysics Data System (ADS)

    Houghton, J.; Wills, E.; Fike, D. A.

    2012-12-01

    Microbially mediated reactions involving elemental sulfur in low temperature hydrothermal environments are a critical component of the net hydrothermal flux of sulfur to the global oceans. We assess here the physiological impact on sulfur speciation and isotopic composition of two microbial strains at a range of pH conditions consistent with the sharp gradients found in seafloor hydrothermal environments. Thiomicrospira thermophila and T. crunogena, both isolated from hydrothermal vents at East Pacific Rise, were grown with thiosulfate as the electron donor under aerobic, closed system conditions at controlled pH and optimal temperature (35°C). T. thermophila at pH 8 produced sulfate at a 1:1 ratio with thiosulfate consumption during exponential growth, with the ratio decreasing as pH decreases. This stoichiometric ratio decreases more steeply as a function of pH during metabolism by T. crunogena. Sulfate:thiosulfate ratios less than one indicate the production of alternative oxidized sulfur compounds such as polythionates. The rate of sulfate production is comparable in both strains and is dependent on pH, decreasing from 0.8mM/hr at pH 8 to 0.2mM/hr at pH 5.6. Fractionation of 34S expressed as Δ34S between reactant and product range from 0‰ to 3‰ for both sulfate and elemental sulfur produced, with no difference between products in pH buffered experiments (pH 5.6 and 8.0). However, in unbuffered experiments during which growth causes pH to decrease from 7 to below 4.5, Δ34S(S2O3-SO4) is consistently larger than Δ34S(S2O3-S) in both strains by a factor of 2. The metabolic activity of these (and similar) strains indicate that complex and cryptic sulfur cycling may be occurring in the subsurface, associated with only minimal variation in the δ34S isotopic composition of sulfate and elemental sulfur.

  17. Sulfur isotope evidence for low and fluctuating sulfate levels in the Late Devonian ocean and the potential link with the mass extinction event

    NASA Astrophysics Data System (ADS)

    Sim, Min Sub; Ono, Shuhei; Hurtgen, Matthew T.

    2015-06-01

    High amplitude positive carbon isotope excursions in the Late Devonian, the punctata and Kellwasser events, reflect major perturbations in the global carbon cycle that have been attributed to increased continental weathering and subsequent ocean eutrophication. Despite the comparable carbon isotope anomalies, however, a major extinction has been reported only for the Kellwasser Events, while the punctata Event is marked by low extinction intensity. This study presents multiple sulfur isotope records of carbonate-associated sulfate (CAS) and pyrite from Late Devonian sections in the Great Basin, USA, in order to document changes in the coupled (or decoupled) geochemical cycles of carbon and sulfur during the punctata and Upper Kellwasser events. A positive sulfur isotope shift in both CAS and pyrite accompanies the onset of the punctata Event, but to a larger extent in the latter. As a result, the sulfur isotope offset between CAS and pyrite (Δ34SCAS-py) dropped to less than 10‰. In the middle of the punctata Event, a sharp negative δ34SCAS excursion and negative Δ34SCAS-py values coincide with the Alamo impact. Unlike the rapid δ34Spy and δ34SCAS oscillations associated with the punctata Event, the Upper Kellwasser was a period of relative stability, except for a brief δ34SCAS drop before the event. Paired sulfur isotope data, aided by a simple box model, suggest that the geochemical cycle of sulfur may have been partly responsible for the contrasting biological responses that define these events. High stratigraphic δ34Spy and δ34SCAS variability, coupled with strong reservoir effect, demonstrates a relatively small oceanic sulfate pool existed during the punctata Event. Further, the Alamo impact likely triggered the rapid oxidation of microbially-produced sulfide within this event. The expansion of sulfidic bottom water thus may have been impeded during the punctata Event. In contrast, the lack of a positive shift in δ34SCAS and sizable Δ34SCAS

  18. A nitrogen and sulfur isotope investigation of redox conditions occurring in a shallow outwash aquifer.

    NASA Astrophysics Data System (ADS)

    Spalding, R.; Hartke, E.

    2001-12-01

    The sources and distribution of elevated nitrate and sulfate concentrations were determined using nitrogen and sulfur isotopes in groundwater from an unconfined outwash aquifer located in Jackson County, southern Indiana. Land use is mostly agricultural. Local farmers apply nitrogeneous inorganic fertilizers to their fields. In addition, two commercial confined feedlots house over two million chickens, and wastes are stored in seven interconnected lagoons at the larger feedlot. These wastes are later applied to an adjacent field via spray irrigation. Over 50 shallow wells (5 m deep), domestic wells (7 m deep) and deep wells (15to 20 m deep) were sampled over a two- year period to monitor nitrogen and sulfur inputs from these sources. Most shallow groundwater in the study area is above the EPA drinking water standards for nitrate-N (>10 mgL). Nitrate concentrations are highest down gradient from the spray irrigation field (53.5 mgL), yet are also elevated in up gradient groundwaters. Nitrogen isotopes are enriched in the heavier isotope (d15N-NO3 > +13.7 ooo) down gradient from the large feedlot and lightest signatures (d15N-NO3 < +2.0 ooo) are found in up gradient groundwater underlying fields that use inorganic fertilizers. Analytes associated with feedlot wastes (sodium, potassium, chloride and sulfate) are also elevated down gradient from the larger feedlot. Deep groundwater has no nitrate and higher sulfate concentrations than shallow waters. In two sets of multi-level wells, enrichment in both oxygen and nitrogen isotopes indicates that denitrification may occur at two depths: 1) locally in shallow waters adjacent to the waste lagoons; and 2) in deeper waters (approximately 10 m) throughout the study area. Sulfate isotopic signatures in deep groundwater approach the signature of pyrite found within the outwash (d34S-SO4 = -11.6 ooo). Autotrophic denitrification may be occurring where nitrate is reduced and the oxidation of pyrite is adding sulfate with depth.

  19. Sulfur isotopic evidence for chemocline upward excursions during the end-Permian mass extinction

    NASA Astrophysics Data System (ADS)

    Riccardi, Anthony L.; Arthur, Michael A.; Kump, Lee R.

    2006-12-01

    The latest Permian was a time of major change in ocean chemistry, accompanying the greatest mass extinction of the Phanerozoic. To examine the nature of these changes, samples from two well-studied marine sections that span the Permian-Triassic boundary have been analyzed: the Meishan and Shangsi sections located in Southern China. Isotopic analysis of the carbonate-associated sulfate in these samples provides a detailed record of several isotopic shifts in δ 34S CAS approaching and across the PTB, ranging from +30 to -15‰ (VCDT), with repeated asynchronous fluctuations at the two locations. We interpret the patterns of isotopic shifts, in conjunction with other data, to indicate a shallow unstable chemocline overlying euxinic deep-water which periodically upwelled into the photic zone. These chemocline upward excursion events introduced sulfide to the photic zone stimulating a bloom of phototrophic sulfur oxidizing bacteria. We hypothesize that elemental sulfur globules produced by these organisms and 34S-depleted pyrite produced in the euxinic water column were deposited in the sediment; later oxidation led to incorporation as CAS. This created the large changes to the δ 34S CAS observed in the latest Permian at these locations.

  20. Seawater sulfate reduction and sulfur isotope fractionation in basaltic systems: interaction of seawater with fayalite and magnetite at 200–350°C

    USGS Publications Warehouse

    Shanks, Wayne C.; Bischoff, James L.; Rosenbauer, Robert J.

    1981-01-01

    Systematics of sulfur isotopes in the 250 and 350°C experiments indicate that isotopic equilibrium is reached, and can be modeled as a Rayleigh distillation process. Isotopic composition of hydrothermally produced H2S in natural systems is strongly dependent upon the seawater/basalt ratio in the geothermal system, which controls the relative sulfide contributions from the two important sulfur sources, seawater sulfate and sulfide phases in basalt. Anhydrite precipitation during geothermal heating severely limits sulfate ingress into high temperature interaction zones. Quantitative sulfate reduction can thus be accomplished without producing strongly oxidized rocks and resultant sulfide sulfur isotope values represent a mixture of seawater and basaltic sulfur.

  1. Sulfur isotope study of the Velardeña skarn (Zn-Pb), Durango, Mexico

    NASA Astrophysics Data System (ADS)

    Jimenez, A.

    2012-04-01

    Sulfur isotope study of the Velardeña skarn (Zn-Pb), Durango, Mexico Abigail Jimenez-Franco1*, Pura Alfonso Abella2, Carles Canet3, Eduardo González-Partida4 1 Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México, Ciudad Universitaria, Delegación Coyoacán, 04510 México D.F., Mexico 2 Departament d'Enginyeria Minera i Recursos Naturals, Universitat Politècnica de Catalunya, Av de Les Bases de Manresa 61-73, 08242 Manresa. 3Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Delegación Coyoacán, 04510 México D.F., Mexico 4Centro de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, 76230 Santiago de Querétaro, Qro., Mexico The Velardeña mining district is located in north-eastern part of the state of Durango, in northern of Mexico. The ore deposit is a lead-zinc, garnet-rich skarn developed at the contact between granite porphyry dikes (Eocene) and well-laminated limestones with interbedded chert (Albian-Cenomanian). A study of sulfur isotopes has been carried out in various sulfide minerals of the ores of Velardeña, in order to: (a) constrain the possible sources of sulfur and, therefore, better understand the sulfide mineralizing processes, and (b) to estimate the temperature of the ore-forming stage of the skarn. Sulfur isotope analyses were performed in 21 pure fractions of sulfide minerals of the ore mineralization (pyrite, chalcopyrite, sphalerite and galena). The mineral separation was performed using a series of sieves, and the purity of the samples was verified under a binocular microscope. Isotopic analyses were done on a Finnigan MAT Delta C flow elemental analyzer coupled to a TC-EA, according with the method of Giesemann et al. (1974). The δ34S values of the analyzed sulfides range mostly between -0.6 and +2.6 ‰ (relative to the CDT standard). These values are indicative of a magmatic source of sulfur. A single analysis falls

  2. Biosynthesis and Isotopic Composition of Bacteriochlorophyll a and Okenone in Purple Sulfur Bacteria

    NASA Astrophysics Data System (ADS)

    Smith, D.; Scott, J. H.; Steele, A.; Cody, G. D.; Ohara, S.; Bowden, R.; Fogel, M. L.

    2011-12-01

    Phototrophic sulfur bacteria play an integral part in the anaerobic cycling of sulfur. Bacteriochloroyphll a (Bchl a) is a well-studied photosynthetic compound required for photosynthesis in the organisms that possess it. The only known fossil of purple sulfur bacteria (PSB) in the geologic record is okenane, believed to be of biologic origin originating from the carotenoid pigment okenone, which has only been documented in eleven species of Chromatiaceae. Organic geochemical studies have identified okenane in preserved organic matter in rocks and ancient sediments and further, okenone production has been observed in modern water columns and sediment surfaces. We have undertaken a comprehensive study on the biosynthesis of bacterial pigments including okenone and C, N, and S isotopic fractionation during various growth modes in controlled laboratory experiments of purple sulfur bacteria. Cultures of Marichromatium purpuratum 1591, M. purpuratum 1711, Thiocapsa marina 5653, and FGL21 (isolated from the chemocline of Fayetteville Green Lake, NY) were grown under autotrophic and photoheterotrophic (e.g. acetate or pyruvate) conditions in batch cultures. Concentrations of okenone and Bchl a were quantified as a function of time and growth by Ultra Performance-Liquid Chromatography-Mass Spectrometry (UP-LC-MS) and spectrophotometry. Overall okenone and Bchl a concentrations reached μM levels in the cultures. At stationary phase, all four strains achieved concentrations of okenone and Bchl a that were approximately 2.5 fM and 0.2 fM per cell, respectively, with okenone to Bchl a ratios of approximately 12 to 1. Isotope Ratio Mass Spectrometry (IRMS) was performed on bulk cells and compound specific analysis of Bchl a and okenone to better understand the fractionation associated with the production of the compounds.

  3. Sulfur and oxygen isotope study of sulfate reduction in experiments with natural populations from Fællestrand, Denmark

    NASA Astrophysics Data System (ADS)

    Farquhar, James; Canfield, Don E.; Masterson, Andrew; Bao, Huiming; Johnston, David

    2008-06-01

    This study investigates the sulfur and oxygen isotope fractionations of dissimilatory sulfate reduction and works to reconcile the relationships between the oxygen and sulfur isotopic and elemental systems. We report results of experiments with natural populations of sulfate-reducing bacteria using sediment and seawater from a marine lagoon at Fællestrand on the northern shore of the island of Fyn, Denmark. The experiments yielded relatively large magnitude sulfur isotope fractionations for dissimilatory sulfate reduction (up to approximately 45‰ for 34S/32S) with higher δ18O accompanying higher δ34S, similar to that observed in previous studies. The seawater used in the experiments was spiked by addition of 17O-labeled water and the 17O content of residual sulfate was found to depend on the fraction of sulfate reduced in the experiments. The 17O data provides evidence for recycling of sulfur from metabolic intermediates and for an 18O/16O fractionation of ∼25-30‰ for dissimilatory sulfate reduction. The close correlation between the 17O data and the sulfur isotope data suggests that isotopic exchange between cell water and external water (reactor water) was rapid under experimental conditions. The molar ratio of oxygen exchange to sulfate reduction was found to be about 2.5. This value is slightly lower than observed in studies of natural ecosystems [e.g., Wortmann U. G., Chernyavsky B., Bernasconi S. M., Brunner B., Böttcher M. E. and Swart P. K. (2007) Oxygen isotope biogeochemistry of pore water sulfate in the deep biosphere: dominance of isotope exchange reactions with ambient water during microbial sulfate reduction (ODP Site 1130). Geochim. Cosmochim. Acta71, 4221-4232]. Using recent models of sulfur isotope fractionations we find that our combined sulfur and oxygen isotopic data places constraints on the proportion of sulfate recycled to the medium (78-96%), the proportion of sulfur intermediate sulfite that was recycled by way of APS to sulfate

  4. Sulfur isotope fractionation during microbial sulfate reduction by toluene-degrading bacteria

    NASA Astrophysics Data System (ADS)

    Bolliger, Christof; Schroth, Martin H.; Bernasconi, Stefano M.; Kleikemper, Jutta; Zeyer, Josef

    2001-10-01

    Sulfate-reducing bacteria contribute considerably to the mineralization of petroleum hydrocarbons (PHC) in contaminated environments. Stable sulfur isotope fractionation during microbial sulfate reduction was investigated in microcosm experiments with different cultures of sulfate-reducing bacteria for various initial sulfate concentrations using toluene as the sole carbon source. Experiments were conducted with the marine strain Desulfobacula toluolica, the fresh water strain PRTOL1, and an enrichment culture from a PHC-contaminated aquifer. Sulfate reduction rates ranged from 7 ± 1 to 494 ± 9 nmol cm -3 d -1, whereas specific sulfate reduction rates (sSRR) ranged from 8.9 × 10 -15 to 3.9 × 10 -13 ± 9.2 × 10 -14 mol cell -1 d -1. Calculated enrichment factors (ɛ) for the fractionation of stable sulfur isotopes during microbial sulfate reduction ranged from 19.8 ± 0.9 to 46.9 ± 2.1‰. In general, values of ɛ and sSRR obtained in our experiments were similar to those reported previously for sulfate-reducing bacteria incubated with readily available carbon sources under optimal growth conditions. Moreover, we found no obvious correlation between ɛ and sSRR values when data from all our microcosm experiments were combined or when we combined our data with several previously published data sets. In contrast, ɛ values determined in our enrichment culture experiments (average 23.5 ± 4.3‰) agreed well with ɛ values determined in a recent field study performed in situ in a PHC-contaminated aquifer. Thus, results from this laboratory study provide valuable information on stable sulfur isotope fractionation during microbial sulfate reduction under conditions that more closely resemble those in PHC-contaminated environments, i.e., for a variety of sulfate concentrations, including low sulfate concentrations, and for a an important PHC-constituent (toluene) used as sole carbon source.

  5. Sulfur isotope variability in biogenic pyrite: Reflections of heterogeneous bacterial colonization?

    SciTech Connect

    Kohn, M.J.; Riciputi, L.R.; Stakes, D.; Orange, D.L.

    1998-11-01

    The top 20 cm of sediments at active cold seeps in Monterey Bay, coastal California, contain framboidal pyrite that occurs as infillings and pseudomorphs of the chambers of the tests of foraminifera and rarely as irregularly shaped grains. Sulfur isotope compositions obtained with the ion microprobe show depletions in {sup 34}S and large variations both within and among these pyrite grains. Backscattered-electron imaging reveals three types of pyrite: isolated framboids in a porous aggregation, agglomerated framboids with cementing interstitial pyrite, and recrystallized pyrite with isolated relicts of framboids. In individual grains, RF-pyrite cores grade into F+I-pyrite toward grain rims, and F+I-pyrite grades into PF-pyrite at the grain edges. These textures are consistent with a paragenetic sequence whereby framboids first agglomerate (PF-pyrite), then cement (F+I-pyrite), and finally recrystallize (RF-pyrite). The {delta}{sup 34}S values of RF-pyrite are generally lower than that of F+I-pyrite; if the paragenetic sequence is correct, then this trend parallels the regular core-rim isotopic zoning observed in some grains. The implied increase in {delta}{sup 14}S with time is consistent with Rayleigh fractionation of sulfur in a closed system. Bacteria are intimately involved in the production of pyrite from the samples, and heterogeneous colonization by bacteria provides a simple explanation for the sulfur isotope heterogeneity among and within grains: The foraminifera provide open space for colonization and local nutrients for bacterial growth, whereas the cell walls of the bacteria may provide a local nucleation site for sulfides.

  6. 3.4-Billion-year-old biogenic pyrites from Barberton, South Africa: sulfur isotope evidence.

    PubMed

    Ohmoto, H; Kakegawa, T; Lowe, D R

    1993-10-22

    Laser ablation mass spectroscopy analyses of sulfur isotopic compositions of microscopic-sized grains of pyrite that formed about 3.4 billion years ago in the Barberton Greenstone Belt, South Africa, show that the pyrite formed by bacterial reduction of seawater sulfate. These data imply that by about 3.4 billion years ago sulfate-reducing bacteria had become active, the oceans were rich in sulfate, and the atmosphere contained appreciable amounts (>10(-13) of the present atmospheric level) of free oxygen. PMID:11539502

  7. 3.4-Billion-year-old biogenic pyrites from Barberton, South Africa: sulfur isotope evidence

    NASA Technical Reports Server (NTRS)

    Ohmoto, H.; Kakegawa, T.; Lowe, D. R.

    1993-01-01

    Laser ablation mass spectroscopy analyses of sulfur isotopic compositions of microscopic-sized grains of pyrite that formed about 3.4 billion years ago in the Barberton Greenstone Belt, South Africa, show that the pyrite formed by bacterial reduction of seawater sulfate. These data imply that by about 3.4 billion years ago sulfate-reducing bacteria had become active, the oceans were rich in sulfate, and the atmosphere contained appreciable amounts (>>10(-13) of the present atmospheric level) of free oxygen.

  8. Massive sulfide deposits and hydrothermal solutions: incremental reaction modeling of mineral precipitation and sulfur isotopic evolution

    SciTech Connect

    Janecky, D.R.

    1986-01-01

    Incremental reaction path modeling of chemical and sulfur isotopic reactions occurring in active hydrothermal vents on the seafloor, in combination with chemical and petrographic data from sulfide samples from the seafloor and massive sulfide ore deposits, allows a detailed examination of the processes involved. This paper presents theoretical models of reactions of two types: (1) adiabatic mixing between hydrothermal solution and seawater, and (2) reaction of hydrothermal solution with sulfide deposit materials. In addition, reaction of hydrothermal solution with sulfide deposit minerals and basalt in feeder zones is discussed.

  9. 3.4-Billion-Year-Old Biogenic Pyrites from Barberton, South Africa: Sulfur Isotope Evidence

    NASA Astrophysics Data System (ADS)

    Ohmoto, Hiroshi; Kakegawa, Takeshi; Lowe, Donald R.

    1993-10-01

    Laser ablation mass spectroscopy analyses of sulfur isotopic compositions of microscopic-sized grains of pyrite that formed about 3.4 billion years ago in the Barberton Greenstone Belt, South Africa, show that the pyrite formed by bacterial reduction of seawater sulfate. These data imply that by about 3.4 billion years ago sulfate-reducing bacteria had become active, the oceans were rich in sulfate, and the atmosphere contained appreciable amounts (> > 10-13 of the present atmospheric level) of free oxygen.

  10. 3.4-Billion-year-old biogenic pyrites from Barberton, South Africa: sulfur isotope evidence.

    PubMed

    Ohmoto, H; Kakegawa, T; Lowe, D R

    1993-10-22

    Laser ablation mass spectroscopy analyses of sulfur isotopic compositions of microscopic-sized grains of pyrite that formed about 3.4 billion years ago in the Barberton Greenstone Belt, South Africa, show that the pyrite formed by bacterial reduction of seawater sulfate. These data imply that by about 3.4 billion years ago sulfate-reducing bacteria had become active, the oceans were rich in sulfate, and the atmosphere contained appreciable amounts (>10(-13) of the present atmospheric level) of free oxygen.

  11. Nonadiabatic calculations of ultraviolet absorption cross section of sulfur monoxide: Isotopic effects on the photodissociation reaction

    SciTech Connect

    Danielache, Sebastian O.; Tomoya, Suzuki; Nanbu, Shinkoh; Kondorsky, Alexey; Tokue, Ikuo

    2014-01-28

    Ultraviolet absorption cross sections of the main and substituted sulfur monoxide (SO) isotopologues were calculated using R-Matrix expansion technique. Energies, transition dipole moments, and nonadiabatic coupling matrix elements were calculated at MRCI/AV6Z level. The calculated absorption cross section of {sup 32}S{sup 16}O was compared with experimental spectrum; the spectral feature and the absolute value of photoabsorption cross sections are in good agreement. Our calculation predicts a long lived photoexcited SO* species which causes large non-mass dependent isotopic effects depending on the excitation energy in the ultraviolet region.

  12. Constraints from sulfur isotopes on the origin of gypsum at concrete/claystone interfaces

    NASA Astrophysics Data System (ADS)

    Lerouge, Catherine; Claret, Francis; Tournassat, Christophe; Grangeon, Sylvain; Gaboreau, Stéphane; Boyer, Bernard; Borschnek, Daniel; Linard, Yannick

    Two in situ concrete/claystone interfaces were sampled at the laboratory level in the Andra Meuse/Haute Marne (France) Underground Research Laboratory (URL) in order to study five years of interactions between Callovian-Oxfordian (COx) claystone and two cementitious materials (concrete bottom slab and shotcrete on the walls of the main gallery), with a specific focus on sulfur. Combined mineralogical, chemical and sulfur isotopic investigations were carried out to define the degree of the perturbation of the sulfur system in the claystone and in both the cementitious materials. At both interfaces, results show that the main perturbation on the claystone side is the formation of scarce μm-sized gypsum, the sulfur content of which is essentially derived from pyrite oxidation. The distribution of gypsum is highly correlated with the fissure network of the damaged zone due to excavation of the gallery. Its presence is also often associated with a loss of cohesion of the concrete/claystone interface. Due to the small amounts of gypsum and its μm-size, measurements were performed by ion microprobe. Adaptations were needed on account of the reactivity of gypsum and sulfates in general under the beam. The use of ion microprobe analysis provided evidence of high local isotopic heterogeneity that could be attributed to kinetic fractionation effects. Some analyses suggest a minor contribution of dissolved sulfates in pore water of claystone and possibly of concrete. The perturbation on the concrete side is marked by a significant increase in the bulk sulfur content within three millimeters of the interface with the claystone, showing a sulfur gradient from claystone to concrete. The main objective of this work was to define the extent of the chemical and mineralogical perturbations, taking into account in situ URL conditions, i.e. hydrodynamic conditions (shotcrete sprayed on the gallery walls and subjected to ventilation of the galleries), damaged zone of claystone induced

  13. Sulfur isotope dynamics in two central european watersheds affected by high atmospheric deposition of SO x

    NASA Astrophysics Data System (ADS)

    Novák, Martin; Kirchner, James W.; Groscheová, Hana; Havel, Miroslav; Černý, Jiří; Krejčí, Radovan; Buzek, František

    2000-02-01

    Sulfur fluxes and δ34S values were determined in two acidified small watersheds located near the Czech-German border, Central Europe. Sulfur of sulfate aerosol in the broader region (mean δ 34S of 7.5‰ CDT) was isotopically heavier than sulfur of airborne SO 2 (mean δ 34S of 4.7‰). The annual atmospheric S deposition to the Jezeřı´ watershed decreased markedly in 1993, 1994, and 1995 (40, 33, and 29 kg/ ha · yr), reflecting reductions in industrial S emissions. Sulfur export from Jezeří via surface discharge was twice atmospheric inputs, and increased from 52 to 58 to 85 kg/ha · yr over the same three-year period. The δ 34S value of Jezeřı´ streamflow was 4.5 ± 0.3‰, intermediate between the average atmospheric deposition (5.4 ± 0.2‰) and soil S (4.0 ± 0.5‰), suggesting that the excess sulfate in runoff comes from release of S from the soil. Bedrock is not a plausible source of the excess S, because its S concentration is very low (<0.003 wt.%) and because its δ 34S value is too high (5.8‰) to be consistent with the δ 34S of runoff. A sulfur isotope mixing model indicated that release of soil S accounted for 64 ± 33% of sulfate S in Jezeřı´ discharge. Approximately 30% of total sulfate S in the discharge were organically cycled. At Načetı´n, the same sequence of δ34S IN > δ34S OUT > δ34S SOIL was observed. The seasonality found in atmospheric input (higher δ 34S in summer, lower δ 34S in winter) was preserved in shallow (<10 cm) soil water, but not in deeper soil water. δ 34S values of deeper (>10 cm) soil water (4.8 ± 0.2‰) were intermediate between those of atmospheric input (5.9 ± 0.3‰) and Nac̆etín soils (2.4 ± 0.1‰), again suggesting that remobilization of soil S accounts for a significant fraction (roughly 40 ± 10%) of the S in soil water at Načetı´n. The inventories of soil S at both of these sites are legacies of more intense atmospheric pollution during previous decades, and are large enough (740

  14. The ecophysiology of sulfur isotope fractionation by sulfate reducing bacteria in response to variable environmental conditions

    NASA Astrophysics Data System (ADS)

    Leavitt, W.; Bradley, A. S.; Johnston, D. T.; Pereira, I. A. C.; Venceslau, S.; Wallace, C.

    2014-12-01

    Microbial sulfate reducers (MSR) drive the Earth's biogeochemical sulfur cycle. At the heart of this energy metabolism is a cascade of redox transformations coupling organic carbon and/or hydrogen oxidation to the dissimilatory reduction of sulfate to sulfide. The sulfide produced is depleted in the heavier isotopes of sulfur relative to sulfate. The magnitude of discrimination (fractionation) depends on: i) the cell-specific sulfate reduction rate (csSRR, Kaplan & Rittenberg (1964) Can. J. Microbio.; Chambers et al. (1975) Can. J. Microbio; Sim et al. (2011) GCA; Leavitt et al. (2013) PNAS), ii) the ambient sulfate concentration (Harrison & Thode (1958) Research; Habicht et al. (2002) Science; Bradley et al. in review), iii) both sulfate and electron donor availability, or iv) an intrinsic physiological limitation (e.g. cellular division rate). When neither sulfate nor electron donor limits csSRR a more complex function relates the magnitude of isotope fractionation to cell physiology and environmental conditions. In recent and on-going work we have examined the importance of enzyme-specific fractionation factors, as well as the influence of electron donor or electron acceptor availability under carefully controlled culture conditions (e.g. Leavitt et al. (2013) PNAS). In light of recent advances in MSR genetics and biochemistry we utilize well-characterized mutant strains, along with a continuous-culture methodology (Leavitt et al. (2013) PNAS) to further probe the fractionation capacity of this metabolism under controlled physiological conditions. We present our latest findings on the magnitude of S and D/H isotope fractionation in both wild type and mutant strains. We will discuss these in light of recent theoretical advances (Wing & Halevy (2014) PNAS), examining the mode and relevance of MSR isotope fractionation in the laboratory to modern and ancient environmental settings, particularly anoxic marine sediments.

  15. The abiotic disproportionation of sulfur dioxide (SO2) produces sulfate with an oxygen isotope signature close to the isotope composition of seawater sulfate

    NASA Astrophysics Data System (ADS)

    Müller, Inigo A.; Brunner, Benjamin; Max, Thomas; Breuer, Christian; Reeves, Eoghan P.; Thal, Janis; Bernasconi, Stefano M.; Bach, Wolfgang

    2013-04-01

    Whereas the sulfur isotope effects during the abiotic disproportionation of SO2 were thoroughly investigated in the last years, data on the oxygen isotope signature of produced sulfate is scarce. To fill in this gap in knowledge, we performed laboratory experiments which simulated the abiotic SO2 disproportionation at temperatures ranging from 150°C to 320°C. In our experiments SO2 disproportionated rapidly into sulfate and elemental sulfur. The oxygen isotope fractionation between produced sulfate and water is in the range of the observed oxygen isotope offset between seawater sulfate and seawater. The isotope fractionations observed for the experiments is likely composed of an initial kinetic oxygen isotope fractionation, which is rapidly overprinted by equilibrium oxygen isotope between sulfate and water (reaching completion probably within a time frame of ½ to 1 hour. Our observations raise the questions if disproportionation of magmatic SO2 in submarine hydrothermal vent systems is an important control for today's seawater sulfate isotope composition, and if so, if marine hydrothermal SO2 disproportiantion shaped the oxygen isotope signature of marine sulfate over geological times.

  16. Carbon isotope fractionation by thermophilic phototrophic sulfur bacteria: evidence for autotrophic growth in natural populations

    NASA Technical Reports Server (NTRS)

    Madigan, M. T.; Takigiku, R.; Lee, R. G.; Gest, H.; Hayes, J. M.

    1989-01-01

    Purple phototrophic bacteria of the genus Chromatium can grow as either photoautotrophs or photoheterotrophs. To determine the growth mode of the thermophilic Chromatium species, Chromatium tepidum, under in situ conditions, we have examined the carbon isotope fractionation patterns in laboratory cultures of this organism and in mats of C. tepidum which develop in sulfide thermal springs in Yellowstone National Park. Isotopic analysis (13C/12C) of total carbon, carotenoid pigments, and bacteriochlorophyll from photoautotrophically grown cultures of C. tepidum yielded 13C fractionation factors near -20%. Cells of C. tepidum grown on excess acetate, wherein synthesis of the Calvin cycle enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase ribulose bisphosphate carboxylase) was greatly repressed, were isotopically heavier, fractionation factors of ca. -7% being observed. Fractionation factors determined by isotopic analyses of cells and pigment fractions of natural populations of C. tepidum growing in three different sulfide thermal springs in Yellowstone National Park were approximately -20%, indicating that this purple sulfur bacterium grows as a photoautotroph in nature.

  17. Laboratory chalcopyrite oxidation by Acidithiobacillus ferrooxidans: Oxygen and sulfur isotope fractionation

    USGS Publications Warehouse

    Thurston, R.S.; Mandernack, K.W.; Shanks, Wayne C.

    2010-01-01

    Laboratory experiments were conducted to simulate chalcopyrite oxidation under anaerobic and aerobic conditions in the absence or presence of the bacterium Acidithiobacillus ferrooxidans. Experiments were carried out with 3 different oxygen isotope values of water (??18OH2O) so that approach to equilibrium or steady-state isotope fractionation for different starting conditions could be evaluated. The contribution of dissolved O2 and water-derived oxygen to dissolved sulfate formed by chalcopyrite oxidation was unambiguously resolved during the aerobic experiments. Aerobic oxidation of chalcopyrite showed 93 ?? 1% incorporation of water oxygen into the resulting sulfate during the biological experiments. Anaerobic experiments showed similar percentages of water oxygen incorporation into sulfate, but were more variable. The experiments also allowed determination of sulfate-water oxygen isotope fractionation, ??18OSO4-H2O, of ~ 3.8??? for the anaerobic experiments. Aerobic oxidation produced apparent ??SO4-H2O values (6.4???) higher than the anaerobic experiments, possibly due to additional incorporation of dissolved O2 into sulfate. ??34SSO4 values are ~ 4??? lower than the parent sulfide mineral during anaerobic oxidation of chalcopyrite, with no significant difference between abiotic and biological processes. For the aerobic experiments, a small depletion in ??34SSO4 of ~- 1.5 ?? 0.2??? was observed for the biological experiments. Fewer solids precipitated during oxidation under aerobic conditions than under anaerobic conditions, which may account for the observed differences in sulfur isotope fractionation under these contrasting conditions. ?? 2009 Elsevier B.V.

  18. Fermentation, Hydrogen, and Sulfur Metabolism in Multiple Uncultivated Bacterial Phyla

    SciTech Connect

    Wrighton, Kelly C.; Thomas, BC; Sharon, I; Miller, CS; Castelle, Cindy J; Verberkmoes, Nathan C; Wilkins, Michael J.; Hettich, Robert {Bob} L; Lipton, Mary S; Williams, Ken; Long, Philip E; Banfield, Jillian F.

    2012-01-01

    BD1-5, OP11, and OD1 bacteria have been widely detected in anaerobic environments, but their metabolisms remain unclear owing to lack of cultivated representatives and minimal genomic sampling. We uncovered metabolic characteristics for members of these phyla, and a new lineage, PER, via cultivation-independent recovery of 49 partial to near-complete genomes from an acetate-amended aquifer. All organisms were nonrespiring anaerobes predicted to ferment. Three augment fermentation with archaeal-like hybrid type II/III ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO) that couples adenosine monophosphate salvage with CO2 fixation, a pathway not previously described in Bacteria. Members of OD1 reduce sulfur and may pump protons using archaeal-type hydrogenases. For six organisms, the UGA stop codon is translated as tryptophan. All bacteria studied here may play previously unrecognized roles in hydrogen production, sulfur cycling, and fermentation of refractory sedimentary carbon.

  19. Fermentation, Hydrogen, and Sulfur Metabolism in Multiple Uncultivated Bacterial Phyla

    SciTech Connect

    Wrighton, Kelly C.; Thomas, Brian C.; Sharon, I.; Miller, Christopher S.; Castelle, Cindy; VerBerkmoes, Nathan C.; Wilkins, Michael J.; Hettich, Robert L.; Lipton, Mary S.; Williams, Kenneth H.; Long, Philip E.; Banfield, Jillian F.

    2012-09-27

    BD1-5, OP11, and OD1 bacteria have been widely detected in anaerobic environments, but their metabolisms remain unclear owing to lack of cultivated representatives and minimal genomic sampling. We uncovered metabolic characteristics for members of these phyla, and a new lineage, PER, via cultivation-independent recovery of 49 partial to near-complete genomes from an acetate-amended aquifer. All organisms were nonrespiring anaerobes predicted to ferment. Three augment fermentation with archaeal-like type II and III ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO) that couples adenosine monophosphate salvage with CO2 fixation, a pathway previously not described in Bacteria. Members of OD1 reduce sulfur and may pump protons using archaeal-type hydrogenases. For six organisms, the UGA stop codon is translated as tryptophan. All bacteria studied here may play previously unrecognized roles in hydrogen production, sulfur cycling, and fermentation of refractory sedimentary carbon.

  20. Linking Food Webs and Biogeochemical Processes in Wetlands: Insights From Sulfur Isotopes

    NASA Astrophysics Data System (ADS)

    Stricker, C. A.; Guntenspergen, G. R.; Rye, R. O.

    2005-05-01

    To better understand the transfer of nutrients into prairie wetland food webs we have investigated the cycling of S (via S isotope systematics and geochemistry) in a prairie wetland landscape by characterizing sources (ground water, interstitial water, surface water) and processes in a small catchment comprised of four wetlands in eastern South Dakota. We focused on S to derive process information that is not generally available from carbon isotopes alone. The wetlands chosen for study spanned a considerable range in SO4 concentration (0.1-13.6 mM), which corresponded with landscape position. Ground water δ34SSO4 values remained relatively constant (mean = -13.2 per mil) through time. However, δ34SSO4 values of wetland surface waters ranged from -2.9 to -30.0 per mil (CDT) and were negatively correlated with SO4 concentrations (p<0.05). The isotopic variability of surface water SO4 resulted from mixing with re-oxidized sulfides associated with recently flushed wetland soils. The δ34S signatures of wetland primary (Gastropoda: Stagnicola elodes) and secondary (Odonata: Anax sp.) consumers were significantly related to surface water δ34SSO4 values (p<0.05) suggesting that food web components were responding to changes in the isotopic composition of the S source. Both primary and secondary consumer δ34S signatures differed between wetlands (ANOVA, p<0.05). These data illustrate the complexity of S cycling in prairie wetlands and the influence of wetland hydrologic and biogeochemical processes on prairie wetland food webs. Additionally, this work has demonstrated that sulfur isotopes can provide unique source and process information that cannot be derived from traditional carbon and nitrogen isotope studies.

  1. [Isotopic composition and isotope tracing of sulfur in atmospheric precipitation at the head area of the Three Gorges Reservoir, China].

    PubMed

    Wu, Qi-Xin; Han, Gui-Lin

    2012-07-01

    Rainwater samples were collected in the head area of the Three Gorges Reservoir from June 2009 to July 2010. The SO4(2-) content and the characteristics of sulfur isotopic composition were determined. The results showed that the concentrations of SO4(2-) ranged from 31.4-668. 1 micromol x L(-1) with a weighted average of 161.9 micromol x L(-1), whereas the variation of delta34S values for SO4(2-) ranged from -2.14 per hundred to 6.07 per hundred with an annual average of 2.06 per hundred +/- 1.97 per hundred. Significant seasonal variations were found in the SO4(2-) content, which were higher in winter and spring and lower in summer and autumn. The delta34S values for SO4(2-) measured in winter were much higher than those in the other seasons. Analysis of the delta34S values showed that the biogenic sulfur might have significant contribution to the acidity of rainwater, especially in summer and autumn.

  2. Concentrations and isotope ratios of carbon, nitrogen and sulfur in ocean-floor basalts

    USGS Publications Warehouse

    Sakai, H.; Marais, D.J.D.; Ueda, A.; Moore, J.G.

    1984-01-01

    Fresh submarine basalt glasses from Galapagos Ridge, FAMOUS area, Cayman Trough and Kilauea east rift contain 22 to 160 ppm carbon and 0.3 to 2.8 ppm nitrogen, respectively, as the sums of dissolved species and vesicle-filling gases (CO2 and N2). The large range of variation in carbon content is due to combined effect of depth-dependency of the solubility of carbon in basalt melt and varying extents of vapour loss during magma emplacement as well as in sample crushing. The isotopic ratios of indigenous carbon and nitrogen are in very narrow ranges,-6.2 ?? 0.2% relative to PDB and +0.2 ?? 0.6 %. relative to atmospheric nitrogen, respectively. In basalt samples from Juan de Fuca Ridge, however, isotopically light carbon (??13C = around -24%.) predominates over the indigenous carbon; no indigenous heavy carbon was found. Except for Galapagos Ridge samples, these ocean-floor basalts contain 670 to 1100 ppm sulfur, averaging 810 ppm, in the form of both sulfide and sulfate, whereas basalts from Galapagos Ridge are higher in both sulfur (1490 and 1570 ppm) and iron (11.08% total iron as FeO). The ??34S values average +0.3 ?? 0.5%. with average fractionation factor between sulfate and sulfide of +7.4 ?? 1.6%.. The sulfate/sulfide ratios tend to increase with increasing water content of basalt, probably because the oxygen fugacity increases with increasing water content in basalt melt. ?? 1984.

  3. Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions.

    PubMed

    Hosono, Takahiro; Alvarez, Kelly; Lin, In-Tian; Shimada, Jun

    2015-12-01

    In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ(15)NNO3), carbon in dissolved inorganic carbon (δ(13)CDIC), and sulfur in sulfate (δ(34)SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ(13)CDIC (from -7.7‰ to -12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was -4.7‰), suggesting the contribution of C of trisodium citrate (δ(13)C=-12.4‰). No SO4(2-) and δ(34)SSO4 changes were observed. In the AD experiment, clear fractionation of δ(13)CDIC during DIC consumption (εC=-7.8‰) and δ(34)SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN=-12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field. PMID:26529303

  4. Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions

    NASA Astrophysics Data System (ADS)

    Hosono, Takahiro; Alvarez, Kelly; Lin, In-Tian; Shimada, Jun

    2015-12-01

    In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ15NNO3), carbon in dissolved inorganic carbon (δ13CDIC), and sulfur in sulfate (δ34SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ13CDIC (from - 7.7‰ to - 12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was - 4.7‰), suggesting the contribution of C of trisodium citrate (δ13C = - 12.4‰). No SO42 - and δ34SSO4 changes were observed. In the AD experiment, clear fractionation of δ13CDIC during DIC consumption (εC = - 7.8‰) and δ34SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN = - 12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field.

  5. Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions.

    PubMed

    Hosono, Takahiro; Alvarez, Kelly; Lin, In-Tian; Shimada, Jun

    2015-12-01

    In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ(15)NNO3), carbon in dissolved inorganic carbon (δ(13)CDIC), and sulfur in sulfate (δ(34)SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ(13)CDIC (from -7.7‰ to -12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was -4.7‰), suggesting the contribution of C of trisodium citrate (δ(13)C=-12.4‰). No SO4(2-) and δ(34)SSO4 changes were observed. In the AD experiment, clear fractionation of δ(13)CDIC during DIC consumption (εC=-7.8‰) and δ(34)SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN=-12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field.

  6. Measurements of radioactive and stable sulfur isotopes at Mt. Everest and its geochemical implications

    NASA Astrophysics Data System (ADS)

    Lin, M.; Thiemens, M. H.; Zhang, Q.; Li, C.; Kang, S.; Hsu, S. C.; Zhang, Z.; Su, L.

    2015-12-01

    The Himalayas were recently identified as a global hotspot for deep stratosphere-to-troposphere transport (STT) during spring [1]. Although STT transport in this region may play a vital role in tropospheric chemistry, the hydrological cycle and aquatic ecosystems in Asia, there is no direct measurement of a specific chemical stratospheric tracer to verify and evaluate its possible impact. Here, cosmogenic 35S tracer (half-life: ~87 days) produced in the stratosphere was measured for the first time in surface snow and river runoff samples collected at Mt. Everest in April 2013 using a low-noise liquid scintillation spectroscopy [2]. Strikingly, we find extraordinarily high concentrations of 35S in these samples (>10 times higher than the southern Tibetan Plateau), verifying the Himalayas as a gateway of springtime STT. In light of this, two studies were conducted: a) Measurements of 35SO2 and 35SO42- at the southern Tibetan Plateau reveals that the oxidative life time of SO2 is reduced to 2.1 days under the influence of aged stratospheric air masses from the Himalayas. A concept box model for estimating the influence of STT on surface O3 using 35S tracer is proposed. b) Quadruple stable sulfur isotopes in a sediment core (~250 years) from the Gokyo Lake (the world's highest freshwater lake) [3] near Mt. Everest are being measured to investigate the possible impact of STT on sulfur budget at the Himalayas. The absence of sulfide suggests that bacterial sulfate reduction may be negligible in this lake. Enrichment of uranium (EF ≈ 10) in 20th century samples highlights the impact of atmospheric deposition. S-isotope sulfate anomalies are not found (∆33S and ∆36S ≈ 0‰), implying that sulfate in this lake may be mainly contributed by eolian dust or derived from rock. This is also supported by the low enrichments of most trace elements (EF ≈ 1). Rare earth elements will be used to assist in identifying the potential sources and interpreting the variation of

  7. Microbial sulfate reduction within the Iheya North subseafloor hydrothermal system constrained by quadruple sulfur isotopes

    NASA Astrophysics Data System (ADS)

    Aoyama, S.; Nishizawa, M.; Takai, K.; Ueno, Y.

    2012-12-01

    Subseafloor hydrothermal system may host active and abundant microbial community. Sulfate reduction may be one of the dominant microbial metabolisms among the subseafloor ecosystem. In order to demonstrate and quantify the potential sulfate reducing activity, we analyzed sulfur isotopes (32S/33S/34S/36S) of pore water sulfate extracted from core samples at the Iheya North hydrothermal system in the Okinawa drilled by CHIKYU, 2009 (IODP Leg 331). After drilling, core samples were divided into several sections. Then, pore water was extracted on board, and stored with cadmium chloride for fixing hydrogen sulfide. In our laboratory, the samples were first divided into sulfide precipitate and supernatant liquid by centrifugation. Then, dissolved sulfate was precipitated as BaSO4 by addition of barium chloride into the supernatant liquid. After weighing, the barium sulfate was converted into silver sulfide and subsequently sulfur hexafluoride, which was purified by GC and then introduced into mass spectrometer (MAT253) through newly developed microvolume inlet for precisely determining quadruple sulfur isotopic composition. Based on pore water chemistry and temperature profile, the subseafloor environment are divided into Unit-1, -2 and -3 with depth below surface. In Unit-1 (0-10 mbsf), fresh seawater is circulated, whereas in Unit-3 (>40 mbsf), hot hydrothermal fluid (>150 degrees Celsius) is stored below anhydrite cap. The Unit-2 is the mixing zone between the hydrothermal fluid and seawater. We found that the δ34S value of sulfate in the mixing zone was higher than those expected by simple mixing between seawater sulfate in Unit-1 (-20‰) and the hydrothermal component in Unit-3 (-16‰). The observed 34S-enrichment and decreased sulfate concentration suggest sulfate reduction took place in this hydrothermal system. Based on our model calculation assuming the mixing and reduction, apparent isotope effect for 33ɛ, 34ɛ and 36ɛ are estimated to be -16.5‰, -32.2

  8. Zinc and sulfur isotope variation in sphalerite from carbonate-hosted zinc deposits, Cantabria, Spain

    NASA Astrophysics Data System (ADS)

    Pašava, Jan; Tornos, Fernando; Chrastný, Vladislav

    2014-10-01

    We studied zinc and sulfur isotopes and the chemical composition of sphalerite samples from Picos de Europa (Aliva mine) and sphalerite and hydrozincite samples from La Florida mine, two carbonate-hosted Mississippi Valley-type (MVT) deposits located in northern Spain; despite being close, they are hosted in carbonatic rocks of different ages, Lower Carboniferous and Lower Cretaceous, respectively. The two generations of sphalerite at Picos de Europa show different δ66Zn values (stage 1 sphalerite +0.24 per mil and stage 2 sphalerite from -0.75 to +0.08 per mil). Both generations also differ in the sulfur isotope composition (stage 1 has δ34S = +6.6 and stage 2 has δ34S = -0.9 to +2.9 per mil) and the chemical composition (stage 1 sphalerite, compared to stage 2 sphalerite, is significantly enriched in Pb, As, Mn, Sb, slightly enriched in Ag, Ni, and Cu and depleted in Co, Ga, Tl, Te, Ge, and Sn). We suggest that Zn isotope fractionation was controlled predominantly by pH and T changes. High Zn isotope values reflect rapid precipitation of sphalerite from higher-temperature acidic fluids that carried Zn mostly as chloride species after interaction with carbonate rocks while lower Zn isotope values most likely resulted from a longer precipitation process from fluid at higher pH and decreasing T that carried dominantly Zn sulfide species. At La Florida, sphalerite samples show light 66Zn-depleted signatures with δ66Zn values from -0.80 to -0.01 per mil (mostly between -0.80 and -0.24 per mil) and δ34S values from +10.7 to +15.7 per mil without any relationship between the δ66Zn and δ34S values. Here, the variation in Zn isotope values is interpreted as related to mixing of fluids from two reservoirs. The Zn was carried by a single deep-seated and higher T (~250-320 °C) fluid, and precipitation took place after mixing with a connate S-rich fluid in a system with mH2S > mZn2+ as a result of change in pH, T, and Zn predominant species. The light δ66Zn

  9. Sulfur isotopes of organic matter preserved in 3.45-billion-year-old stromatolites reveal microbial metabolism.

    PubMed

    Bontognali, Tomaso R R; Sessions, Alex L; Allwood, Abigail C; Fischer, Woodward W; Grotzinger, John P; Summons, Roger E; Eiler, John M

    2012-09-18

    The 3.45-billion-year-old Strelley Pool Formation of Western Australia preserves stromatolites that are considered among the oldest evidence for life on Earth. In places of exceptional preservation, these stromatolites contain laminae rich in organic carbon, interpreted as the fossil remains of ancient microbial mats. To better understand the biogeochemistry of these rocks, we performed microscale in situ sulfur isotope measurements of the preserved organic sulfur, including both Δ(33)S and . This approach allows us to tie physiological inference from isotope ratios directly to fossil biomass, providing a means to understand sulfur metabolism that is complimentary to, and independent from, inorganic proxies (e.g., pyrite). Δ(33)S values of the kerogen reveal mass-anomalous fractionations expected of the Archean sulfur cycle, whereas values show large fractionations at very small spatial scales, including values below -15‰. We interpret these isotopic patterns as recording the process of sulfurization of organic matter by H(2)S in heterogeneous mat pore-waters influenced by respiratory S metabolism. Positive Δ(33)S anomalies suggest that disproportionation of elemental sulfur would have been a prominent microbial process in these communities.

  10. Sulfur isotopes of organic matter preserved in 3.45-billion-year-old stromatolites reveal microbial metabolism.

    PubMed

    Bontognali, Tomaso R R; Sessions, Alex L; Allwood, Abigail C; Fischer, Woodward W; Grotzinger, John P; Summons, Roger E; Eiler, John M

    2012-09-18

    The 3.45-billion-year-old Strelley Pool Formation of Western Australia preserves stromatolites that are considered among the oldest evidence for life on Earth. In places of exceptional preservation, these stromatolites contain laminae rich in organic carbon, interpreted as the fossil remains of ancient microbial mats. To better understand the biogeochemistry of these rocks, we performed microscale in situ sulfur isotope measurements of the preserved organic sulfur, including both Δ(33)S and . This approach allows us to tie physiological inference from isotope ratios directly to fossil biomass, providing a means to understand sulfur metabolism that is complimentary to, and independent from, inorganic proxies (e.g., pyrite). Δ(33)S values of the kerogen reveal mass-anomalous fractionations expected of the Archean sulfur cycle, whereas values show large fractionations at very small spatial scales, including values below -15‰. We interpret these isotopic patterns as recording the process of sulfurization of organic matter by H(2)S in heterogeneous mat pore-waters influenced by respiratory S metabolism. Positive Δ(33)S anomalies suggest that disproportionation of elemental sulfur would have been a prominent microbial process in these communities. PMID:22949693

  11. Sulfur isotopes of organic matter preserved in 3.45-billion-year-old stromatolites reveal microbial metabolism

    PubMed Central

    Bontognali, Tomaso R. R.; Sessions, Alex L.; Allwood, Abigail C.; Fischer, Woodward W.; Grotzinger, John P.; Summons, Roger E.; Eiler, John M.

    2012-01-01

    The 3.45-billion-year-old Strelley Pool Formation of Western Australia preserves stromatolites that are considered among the oldest evidence for life on Earth. In places of exceptional preservation, these stromatolites contain laminae rich in organic carbon, interpreted as the fossil remains of ancient microbial mats. To better understand the biogeochemistry of these rocks, we performed microscale in situ sulfur isotope measurements of the preserved organic sulfur, including both Δ33S and . This approach allows us to tie physiological inference from isotope ratios directly to fossil biomass, providing a means to understand sulfur metabolism that is complimentary to, and independent from, inorganic proxies (e.g., pyrite). Δ33S values of the kerogen reveal mass-anomalous fractionations expected of the Archean sulfur cycle, whereas values show large fractionations at very small spatial scales, including values below -15‰. We interpret these isotopic patterns as recording the process of sulfurization of organic matter by H2S in heterogeneous mat pore-waters influenced by respiratory S metabolism. Positive Δ33S anomalies suggest that disproportionation of elemental sulfur would have been a prominent microbial process in these communities. PMID:22949693

  12. Fractionation of Sulfur Isotopes by Desulfovibrio vulgaris Mutants Lacking Periplasmic Hydrogenases or the Type I Tetraheme Cytochrome c3

    NASA Astrophysics Data System (ADS)

    Sim, M.; Ono, S.; Bosak, T.

    2012-12-01

    A large fraction of anaerobic mineralization of organic compounds relies on microbial sulfate reduction. Sulfur isotope fractionation by these microbes has been widely used to trace the biogeochemical cycling of sulfur and carbon, but intracellular mechanisms behind the wide range of fractionations observed in nature and cultures are not fully understood. In this study, we investigated the influence of electron transport chain components on the fractionation of sulfur isotopes by culturing Desulfovibrio vulgaris Hildenborough mutants lacking hydrogenases or type I tetraheme cytochrome c3 (Tp1-c3). The mutants were grown both in batch and continuous cultures. All tested mutants grew on lactate or pyruvate as the sole carbon and energy sources, generating sulfide. Mutants lacking cytoplasmic and periplasmic hydrogenases exhibited similar growth physiologies and sulfur isotope fractionations to their parent strains. On the other hand, a mutant lacking Tp1-c3 (ΔcycA) fractionated the 34S/32S ratio more than the wild type, evolving H2 in the headspace and exhibiting a lower specific respiration rate. In the presence of high concentrations of pyruvate, the growth of ΔcycA relied largely on fermentation rather than sulfate reduction, even when sulfate was abundant, producing the largest sulfur isotope effect observed in this study. Differences between sulfur isotope fractionation by ΔcycA and the wild type highlight the effect of electron transfer chains on the magnitude of sulfur isotope fractionation. Because Tp1-c3 is known to exclusively shuttle electrons from periplasmic hydrogenases to transmembrane complexes, electron transfers in the absence of Tp1-c3 should bypass the periplasmic hydrogen cycling, and the loss of reducing equivalents in the form of H2 can impair the flow of electrons from organic acids to sulfur, increasing isotope fractionation. Larger fractionation by ΔcycA can inform interpretations of sulfur isotope data at an environmental scale as well

  13. [Investigations on Sulfur and Carbon Isotopic Compositions of Potential Polluted Sources in Atmospheric PM₂.₅ in Nanjing Region].

    PubMed

    Shi, Lei; Guo, Zhao-bing; Jiang, Wen-juan; Rui, Mao-ling; Zeng, Gang

    2016-01-15

    Potential pollution sources of atmospheric PM₂.₅ in Nanjing region were collected, and sulfur and carbon isotopic compositions were determined by EA-IRMS synchronously. The results showed that δ³⁴S and δ¹³C values ranged from 1.8‰-3.7‰ and -25.50‰- -23.57‰ in coal soot particles; 4.6‰-9.7‰ and -26.32‰- -23.57‰ in vehicle exhaust; 5.2‰-9.9‰ and -19.30‰- -30.42‰ in straw soot particles, respectively. Besides, the δ¹³C value of dust was -13.45‰. It can be observed that sulfur isotopic compositions in coal soot were lower, while the carbon isotopic composition in dust was higher. Comparing with δ³⁴S and δ¹³C values in domestic and foreign polluted sources, we found that sulfur and carbon isotopes in atmospheric PM₂.₅ in Nanjing region presented an obvious regional characteristics. Therefore, the source spectrum of sulfur and carbon isotopic compositions in Nanjing region might provide an insight into source apportionment of atmospheric PM₂.₅. PMID:27078936

  14. [Investigations on Sulfur and Carbon Isotopic Compositions of Potential Polluted Sources in Atmospheric PM₂.₅ in Nanjing Region].

    PubMed

    Shi, Lei; Guo, Zhao-bing; Jiang, Wen-juan; Rui, Mao-ling; Zeng, Gang

    2016-01-15

    Potential pollution sources of atmospheric PM₂.₅ in Nanjing region were collected, and sulfur and carbon isotopic compositions were determined by EA-IRMS synchronously. The results showed that δ³⁴S and δ¹³C values ranged from 1.8‰-3.7‰ and -25.50‰- -23.57‰ in coal soot particles; 4.6‰-9.7‰ and -26.32‰- -23.57‰ in vehicle exhaust; 5.2‰-9.9‰ and -19.30‰- -30.42‰ in straw soot particles, respectively. Besides, the δ¹³C value of dust was -13.45‰. It can be observed that sulfur isotopic compositions in coal soot were lower, while the carbon isotopic composition in dust was higher. Comparing with δ³⁴S and δ¹³C values in domestic and foreign polluted sources, we found that sulfur and carbon isotopes in atmospheric PM₂.₅ in Nanjing region presented an obvious regional characteristics. Therefore, the source spectrum of sulfur and carbon isotopic compositions in Nanjing region might provide an insight into source apportionment of atmospheric PM₂.₅.

  15. Patterns of mortality among South Florida Manatees: Evidence from oxygen, sulfur and deuterium stable isotopes

    NASA Astrophysics Data System (ADS)

    MacAvoy, S. E.; Bacalan, V.; Kazantseva, M.; Rhodes, J.; Kim, K.

    2012-12-01

    The Florida manatee (Trichechus manatus latirostris) is an endangered marine mammal whose coastal habitat has been heavily altered by human development. Sources of mortality include anthropogenic and environmental causes. Necropsies were completed on 75 deceased individuals, and tissues, including bone samples, were collected for later analysis. This study investigates the utility of manatee bone stable oxygen (δ18O), sulfur (δ34S) and deuterium (δD) for determining where the animals lived (which may not be where they where their bodies were recovered), and the relative importance of marine versus freshwater for the individual animals. The isotopes can provide a "geochemical map" showing the distribution of mortality, aiding in the evaluation of geographical patterns in mortality. The δ18O signatures of the bones ranged from 14 to 18.5‰, with no significant difference between male and female mean values. δ18O significantly decreased with increasing latitude (p=.0016), a trend positively correlated with coastal Florida seawater δ18O literature values obtained from the NASA Global Seawater Oxygen-18 Database (http://data.giss.nasa.gov/o18data/) and the EAIA stable isotope database (http://www.univie.ac.at/cartography/project/wiser/). Bone δ34S indicated the influence of marine versus coastal freshwater dietary sources on the animals. Most individuals showed 34S-depleted signatures, which indicated a non-marine sulfur source; however some individuals clearly had taken up marine sulfate (mean 4.9 ± 3.7‰, range 0.8 to 13.8‰). Deuterium values were not available at the time this abstract was written, however we hypothesize that those values will co-vary with δ18O. We conclude that manatee diets are based on both marine and freshwater sources, but freshwater sources exert more influence. Marine water and manatee δ18O co-vary with latitude, suggesting that stable oxygen isotopes may be useful indicators of the latitude where manatees lived.

  16. Use of stable sulfur isotopes to identify sources of sulfate in Rocky Mountain snowpacks

    USGS Publications Warehouse

    Mast, M.A.; Turk, J.T.; Ingersoll, G.P.; Clow, D.W.; Kester, C.L.

    2001-01-01

    Stable sulfur isotope ratios and major ions in bulk snowpack samples were monitored at a network of 52 high-elevation sites along and near the Continental Divide from 1993 to 1999. This information was collected to better define atmospheric deposition to remote areas of the Rocky Mountains and to help identify the major source regions of sulfate in winter deposition. Average annual ??34S values at individual sites ranged from + 4.0 to + 8.2??? and standard deviations ranged from 0.4 to 1.6???. The chemical composition of all samples was extremely dilute and slightly acidic; average sulfate concentrations ranged from 2.4 to 12.2 ??eql-1 and pH ranged from 4.82 to 5.70. The range of ??34S values measured in this study indicated that snowpack sulfur in the Rocky Mountains is primarily derived from anthropogenic sources. A nearly linear relation between ??34S and latitude was observed for sites in New Mexico, Colorado, and southern Wyoming, which indicates that snowpack sulfate in the southern part of the network was derived from two isotopically distinct source regions. Because the major point sources of SO2 in the region are coal-fired powerplants, this pattern may reflect variations in the isotopic composition of coals burned by the plants. The geographic pattern in ??34S for sites farther to the north in Wyoming and Montana was much less distinct, perhaps rflecting the paucity of major point sources of SO2 in the northern part of the network.

  17. Advances in the measurement of sulfur isotopes by multi-collector ICP-MS (MC-ICP- MS)

    NASA Astrophysics Data System (ADS)

    Ridley, W. I.; Wilson, S. A.; Anthony, M. W.

    2006-12-01

    The demonstrated capability to measure 34S/32S by MC-ICP-MS with a precision (2ó) of ~0.2 per mil has many potential applications in geochemistry. However, a number of obstacles limit this potential. First, to achieve the precision indicated above requires sufficient mass resolution to separate isobaric interferences of 16O2 and 17O2 on 32S and 34S, respectively. These requirements for high resolution mean overall instrument sensitivity is reduced. Second, current methods preclude analysis of samples with complex matrices, a common characteristic of sulfur-bearing geologic materials. Here, we describe and discuss a method that provides both efficient removal of matrix constituents, and provides pre-concentration of S, thus overcoming these obstacles. The method involves the separation of sulfur from matrix constituents by high pressure (1000 psi) ion chromatography (HPIC), followed by isotope measurement using MC-ICP-MS. This combination allows for analysis of liquid samples with a wide range of S concentrations. A powerful advantage of this technique is the efficient separation of many sulfur species from matrix cations and anions (for instance in a seawater or acid mine drainage matrix), as well as the separation of sulfur species, e.g., sulfate, sulfite, thiosulfate, thiocynate, from each other for isotope analysis. The automated HPIC system uses a carbonate-bicarbonate eluent with eluent suppression, and has sufficient baseline separation to collect the various sulfur species as pure fractions. The individual fractions are collected over a specific time interval based upon a pre-determined elution profile and peak retention times. The addition of a second ion exchange column into the system allows pre-concentration of sulfur species by 2-3 orders of magnitude for samples that otherwise would have sulfur concentrations too low to provide precise isotopic ratios. The S isotope ratios are measured by MC-ICP-MS using a desolvating sample introduction system, a

  18. Sulfur Isotopic Inferences of the Controls on Porewater Sulfate Profiles in the Northern Cascadia Margin Gas Hydrate System

    NASA Astrophysics Data System (ADS)

    Bui, T.; Pohlman, J.; Lapham, L.; Riedel, M.; Wing, B. A.

    2010-12-01

    The flux of methane from gas hydrate bearing seeps in the marine environment is partially mitigated by the anaerobic oxidation of methane coupled with sulfate reduction. Sedimentary porewater sulfate profiles above gas hydrate deposits are frequently used to estimate the efficacy of this important microbial biofilter. However, to differentiate how other processes (e.g., sulfate reduction coupled to organic matter oxidation, sulfide re-oxidation and sulfur disproportionation) affect sulfate profiles, a complete accounting of the sulfur cycle is necessary. To this end, we have obtained the first ever measurements of minor sulfur isotopic ratios (33S/32S, 36S/32S), in conjunction with the more commonly measured 34S -32S ratio, from porewater sulfate above a gas hydrate-bearing seep. Characteristic minor isotopic fractionations, even when major isotopic fractionations are similar in magnitude, help to quantify the contributions of different microbial processes to the overall sulfur cycling in the system. Down to sediment depths of 1.5 to 4 meters, the δ34S values of porewater sulfate generally increased in association with a decrease in sulfate concentrations as would be expected for active sulfate reduction. Of greater interest, covariance between the δ34S values and measured minor isotopic fractionation suggests sulfide reoxidation and sulfur disproportionation are important components of the local sulfur cycle. We hypothesize that sulfide reoxidation is coupled to redox processes involving Fe(III) and Mn(IV) reduction and that the reoxidized forms of sulfur are available for additional methane oxidation. Recognizing that sulfate reduction is only one of several microbial processes controlling sulfate profiles challenges current paradigms for interpreting sulfate profiles and may alter our understanding of methane oxidation at gas hydrate-bearing seeps.

  19. Combined Sulfur K-edge XANES Spectroscopy and Stable Isotope Analysis of Fulvic Acids and Groundwater Sulfate Identify Sulfur Cycling in a Karstic Catchment Area

    SciTech Connect

    Einsiedl,F.; Schafer, T.; Northrup, P.

    2007-01-01

    Chemical and isotope analyses on groundwater sulfate, atmospheric deposition sulfate and fulvic acids (FAs) associated sulfur were used to determine the S cycling in a karstic catchment area of the Franconian Alb, Southern Germany. Sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy provided information on the oxidation state and the mechanism of the incorporation of sulfur in FAs. During base flow {delta}{sup 34}S values of groundwater sulfate were slightly depleted to those of recent atmospheric sulfate deposition with mean amount-weighted {delta}{sup 34}S values of around + 3{per_thousand}. The {delta}{sup 18}O values of groundwater sulfate shifted to lower values compared to those of atmospheric deposition and indicated steadiness from base flow to peak flow. The reduced sulfur species (S{sub -1}/thiol; S{sub 0}/thiophene, disulfide, S{sub +2}2/sulfoxide) of soil FAs averaged around 49% of the total sulfur and {delta}{sup 34}S value in FAs was found to be 0.5{per_thousand}. The formation of polysulfides and thiols in FAs in concert with a decreasing isotope value of {delta}{sup 34}S in FAs with respect to those of atmospheric deposition sulfate suggests oxidation of H{sub 2}S, enriched in the {sup 32}S isotope, with organic material. The depletion of {delta}{sup 18}O-SO{sub 4}{sup 2-} by several per mil in groundwater sulfate with respect to those of atmospheric deposition is, therefore, consistent with the hypothesis that SO{sub 4}{sup 2-} has been cycled through the organic S pool as well as that groundwater sulfate is formed by oxidation of H{sub 2}S with organic matter in the mineral soil of the catchment area.

  20. Determination of the sulfur isotope ratio in carbonyl sulfide using gas chromatography/isotope ratio mass spectrometry on fragment ions 32S+, 33S+, and 34S+.

    PubMed

    Hattori, Shohei; Toyoda, Akari; Toyoda, Sakae; Ishino, Sakiko; Ueno, Yuichiro; Yoshida, Naohiro

    2015-01-01

    Little is known about the sulfur isotopic composition of carbonyl sulfide (OCS), the most abundant atmospheric sulfur species. We present a promising new analytical method for measuring the stable sulfur isotopic compositions (δ(33)S, δ(34)S, and Δ(33)S) of OCS using nanomole level samples. The direct isotopic analytical technique consists of two parts: a concentration line and online gas chromatography-isotope ratio mass spectrometry (GC-IRMS) using fragmentation ions (32)S(+), (33)S(+), and (34)S(+). The current levels of measurement precision for OCS samples greater than 8 nmol are 0.42‰, 0.62‰, and 0.23‰ for δ(33)S, δ(34)S, and Δ(33)S, respectively. These δ and Δ values show a slight dependence on the amount of injected OCS for volumes smaller than 8 nmol. The isotope values obtained from the GC-IRMS method were calibrated against those measured by a conventional SF6 method. We report the first measurement of the sulfur isotopic composition of OCS in air collected at Kawasaki, Kanagawa, Japan. The δ(34)S value obtained for OCS (4.9 ± 0.3‰) was lower than the previous estimate of 11‰. When the δ(34)S value for OCS from the atmospheric sample is postulated as the global signal, this finding, coupled with isotopic fractionation for OCS sink reactions in the stratosphere, explains the reported δ(34)S for background stratospheric sulfate. This suggests that OCS is a potentially important source for background (nonepisodic or nonvolcanic) stratospheric sulfate aerosols. PMID:25439590

  1. Geological sulfur isotopes indicate elevated OCS in the Archean atmosphere, solving faint young sun paradox

    PubMed Central

    Ueno, Yuichiro; Johnson, Matthew S.; Danielache, Sebastian O.; Eskebjerg, Carsten; Pandey, Antra; Yoshida, Naohiro

    2009-01-01

    Distributions of sulfur isotopes in geological samples would provide a record of atmospheric composition if the mechanism producing the isotope effects could be described quantitatively. We determined the UV absorption spectra of 32SO2, 33SO2, and 34SO2 and use them to interpret the geological record. The calculated isotopic fractionation factors for SO2 photolysis give mass independent distributions that are highly sensitive to the atmospheric concentrations of O2, O3, CO2, H2O, CS2, NH3, N2O, H2S, OCS, and SO2 itself. Various UV-shielding scenarios are considered and we conclude that the negative Δ33S observed in the Archean sulfate deposits can only be explained by OCS shielding. Of relevant Archean gases, OCS has the unique ability to prevent SO2 photolysis by sunlight at λ >202 nm. Scenarios run using a photochemical box model show that ppm levels of OCS will accumulate in a CO-rich, reducing Archean atmosphere. The radiative forcing, due to this level of OCS, is able to resolve the faint young sun paradox. Further, the decline of atmospheric OCS may have caused the late Archean glaciation. PMID:19706450

  2. Production, preservation, and biological processing of mass-independent sulfur isotope fractionation in the Archean surface environment

    PubMed Central

    Halevy, Itay

    2013-01-01

    Mass-independent fractionation of sulfur isotopes (S MIF) in Archean and Paleoproterozoic rocks provides strong evidence for an anoxic atmosphere before ∼2,400 Ma. However, the origin of this isotopic anomaly remains unclear, as does the identity of the molecules that carried it from the atmosphere to Earth’s surface. Irrespective of the origin of S MIF, processes in the biogeochemical sulfur cycle modify the primary signal and strongly influence the S MIF preserved and observed in the geological record. Here, a detailed model of the marine sulfur cycle is used to propagate and distribute atmospherically derived S MIF from its delivery to the ocean to its preservation in the sediment. Bulk pyrite in most sediments carries weak S MIF because of microbial reduction of most sulfur compounds to form isotopically homogeneous sulfide. Locally, differential incorporation of sulfur compounds into pyrite leads to preservation of S MIF, which is predicted to be most highly variable in nonmarine and shallow-water settings. The Archean ocean is efficient in diluting primary atmospheric S MIF in the marine pools of sulfate and elemental sulfur with inputs from SO2 and H2S, respectively. Preservation of S MIF with the observed range of magnitudes requires the S MIF production mechanism to be moderately fractionating (20–40‰). Constraints from the marine sulfur cycle allow that either elemental sulfur or organosulfur compounds (or both) carried S MIF to the surface, with opposite sign to S MIF in SO2 and H2SO4. Optimal progress requires observations from nonmarine and shallow-water environments and experimental constraints on the reaction of photoexcited SO2 with atmospheric hydrocarbons. PMID:23572589

  3. Fractionation of sulfur isotopes during atmospheric processes: SO2 oxidation and photolysis

    NASA Astrophysics Data System (ADS)

    Harris, E. J.; Sinha, B.; Hoppe, P.; Crowley, J.; Foley, S. F.

    2010-12-01

    Measurements of stable sulfur isotopes can be used to investigate the chemistry of SO2 in the environment. The oxidation pathway of SO2 plays an important role in determining its environmental effect: gaseous oxidation by OH radicals produces gas-phase sulfuric acid that can nucleate to produce new particles and CCN, while heterogeneous oxidation can change the surface properties of existing particles. Stable isotopes have been used in the investigation of these oxidation pathways, but a major limitation is the lack of laboratory studies of the isotopic fractionation factor for the gaseous reaction (Castleman et al., 1974; Leung et al., 2001; Tanaka et al., 1994). An experimental set-up to investigate the kinetic fractionation of 34S/32S (α = k34/k32) during this reaction has been developed. OH radicals are generated by flowing humidified nitrogen past a mercury lamp producing high-energy UV light. SO2 gas with a known isotopic composition reacts with the OH radicals to produce sulfuric acid gas. Collection methods for both H2SO4 and SO2 gases have been characterised. H2SO4 gas is collected in a glass condenser system and washed out with MilliQ water. This collection method introduces no significant isotopic fractionation. SO2 gas is collected in two bubblers containing 6% H2O2 solution at 273 K, which introduces fractionation of 13 ± 2‰ (α = 1.013 ± 0.002) at 273 K, agreeing with aqueous uptake and oxidation (Saltzman et al., 1983). Following collection, BaCl2 is added to precipitate the sulfur as BaSO4 and the solutions are filtered to collect the BaSO4 grains for analysis in the NanoSIMS. Photolytic and aqueous oxidation of SO2 are the main interfering reactions occurring in the system, and were investigated by running the reaction set-up without generating OH radicals. High humidity conditions produce fractionation of 11 ± 7‰ (α = 1.011 ± 0.007) at 293 K, which corresponds well with previous results for the SO2(g)-HSO3-(aq) system (Eriksen, 1972

  4. Sulfur isotope characteristics of metamorphosed Zn-Cu volcanogenic massive sulfides in the Areachap Group, Northern Cape Province, South Africa

    NASA Astrophysics Data System (ADS)

    Bailie, Russell; Gutzmer, Jens; Strauss, Harald; Stüeken, Eva; McClung, Craig

    2010-06-01

    Zn- and Cu-rich massive sulfide ores of volcanogenic origin [volcanogenic massive sulfide (VMS) deposits] occur as stratiform/stratabound lenses of variable size hosted by gneisses, amphibolites, and schists of the Areachap Group, in the Northern Cape Province of South Africa. The Areachap Group represents the highly deformed and metamorphosed remnants of a Mesoproterozoic volcanic arc that was accreted onto the western margin of the Kaapvaal Craton during the ˜1.0-1.2 Ga Namaquan Orogeny. Sulfur isotope data (δ34S) are presented for 57 sulfide separates and one barite sample from five massive sulfide occurrences in the Areachap Group. Although sulfides from each site have distinct sulfur isotope values, all δ34S values fall within a very limited range (3.0‰ to 8.5‰). Barite has a δ34S value of 18.5‰, very different from that of associated sulfides. At one of the studied sites (Kantienpan), a distinct increase in δ34S of sulfides is observed from the massive sulfide lens into the disseminated sulfides associated with a distinct footwall alteration zone. Sulfide-sulfide and sulfide-barite mineral pairs which recrystallized together during amphibolite- and lower granulite facies metamorphism are not in isotopic equilibrium. Sulfur isotope characteristics of sulfides and sulfates of the Zn-Cu ores in the Areachap Group are, however, very similar to base metal sulfide accumulations associated with modern volcanic arcs and unsedimented mid-ocean ridges. It is thus concluded that profound recrystallization and textural reconstitution associated with high-grade regional metamorphism of the massive sulfide ores of the Areachap Group did not result in extensive sulfur isotopic homogenization. This is similar to observations in other metamorphosed VMS deposit districts and confirms that massive sulfide ores remain effectively a closed system for sulfur isotopes for both sulfides and sulfates during metamorphism.

  5. Carbon and sulfur isotopes as tracers of fluid-fluid and fluid-rock interaction in geothermal systems

    NASA Astrophysics Data System (ADS)

    Stefansson, A.; Keller, N. S.; Gunnarsson Robin, J.; Kjartansdottir, R.; Ono, S.; Sveinbjörnsdottir, A. E.

    2014-12-01

    Carbon and sulfur are among major components in geothermal systems. They are found in various oxidation state and present in solid phases and fluids (water and vapor). In order to study the reactions and mass movement within multiphase geothermal systems, we have combined geochemical fluid-fluid and fluid-rock modelling with sulfur and carbon isotope fractionation modelling and compared the results with measured carbon and sulfur isotopes in geothermal fluids (water and vapor) for selected low- and high-enthalpy geothermal systems in Iceland. In this study we have focused on δ34S for H2S in vapor and water and SO4 in water as well as δ13C for CO2 in vapor and water phases. Isotope fractionations for CO2 and H2S between vapor and liquid water, upon aqueous speciation and upon carbonate and sulfide mineral formation were revised. These were combined with reaction modelling involving closed system boiling and progressive water-rock interaction to constrain the mass movement and isotope abundance between various phases. The results indicate that for a closed system, carbon and sulfur isotope abundance is largely dependent on progressive fluid-fluid and fluid-rock interaction and the initial total δ34S and δ13C value of the system. Initially, upon progressive fluid rock interaction the δ34S and δ13C values for the bulk aqueous phase approach that of the host rocks. Secondary mineral formation may alter these values, the exact isotope value of the mineral and resulting aqueous phase depending on aqueous speciation and isotope fractionation factor. In turn, aqueous speciation and mineral saturation depends on progressive fluid-rock interaction, fluid-fluid interaction, temperature and acid supply to the system. Depressurization boiling also results in isotope fractionation, the exact isotope value of the vapor and aqueous phase depending on aqueous speciation and isotope fractionation fractor. In this way, carbon and sulfur isotopes may be used combined with

  6. Delineating the effect of El-Nino Southern Oscillations using oxygen and sulfur isotope anomalies of sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abaunza Quintero, M. M.; Jackson, T.; McCabe, J.; Savarino, J. P.; Thiemens, M. H.

    2013-12-01

    Sulfate aerosols, unlike greenhouse gases, contribute to global cooling by acting as cloud condensation nuclei in the troposphere and by directly reflecting solar radiation in the stratosphere. To understand the long-term effect of natural and anthropogenic sulfate aerosol on the climate cycle, it is critical to obtain a clear picture of the factors controlling the transport and transformation of sulfate aerosols. We have employed both oxygen triple isotopes and sulfur quadruple isotopes on sulfates from Antarctic ice samples to define the oxidation history, long range transport dynamics, and sources of sulfate aerosols over time. The measurements are used to deconvolve the impact of natural and anthropogenic aerosols on the stratospheric sulfate aerosol composition. Sulfate aerosols were extracted from a snow pit at the South Pole (1979-2002) with a high resolution temporal (6 month) record of the winter and summer seasons covering two largest volcanic events, Pinatubo and El-chichon and three largest ENSO events of the century. All three oxygen and four sulfur isotopes were measured on the extracted sulfate (Shaheen et al., 2013). The high temperature pyrolysis (1000oC) of silver sulfate yielded O2 and SO2. The oxygen triple isotopic composition of the O2 gas was used to determine the oxidation history of sulfate aerosol and SO2 gas obtained during this reaction was utilized to measure sulfur quadruple isotopes following appropriate reaction chemistry (Farquhar et al., 2001). The data revealed that oxygen isotope anomalies in Antarctic aerosols (Δ17O = 0.8-3.7‰) from 1990 to 2001 are strongly linked to the variation in ozone levels in the upper stratosphere/lower stratosphere. The variations in ozone levels are reflective of the intensity of the ENSO events and changes in relative humidity in the atmosphere during this time period. Sulfate concentrations and sulfur quadruple isotopic composition and associated anomalies were used to elucidate the sources of

  7. Influence of sulfur-bearing polyatomic species on high precision measurements of Cu isotopic composition

    USGS Publications Warehouse

    Pribil, M.J.; Wanty, R.B.; Ridley, W.I.; Borrok, D.M.

    2010-01-01

    An increased interest in high precision Cu isotope ratio measurements using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has developed recently for various natural geologic systems and environmental applications, these typically contain high concentrations of sulfur, particularly in the form of sulfate (SO42-) and sulfide (S). For example, Cu, Fe, and Zn concentrations in acid mine drainage (AMD) can range from 100??g/L to greater than 50mg/L with sulfur species concentrations reaching greater than 1000mg/L. Routine separation of Cu, Fe and Zn from AMD, Cu-sulfide minerals and other geological matrices usually incorporates single anion exchange resin column chromatography for metal separation. During chromatographic separation, variable breakthrough of SO42- during anion exchange resin column chromatography into the Cu fractions was observed as a function of the initial sulfur to Cu ratio, column properties, and the sample matrix. SO42- present in the Cu fraction can form a polyatomic 32S-14N-16O-1H species causing a direct mass interference with 63Cu and producing artificially light ??65Cu values. Here we report the extent of the mass interference caused by SO42- breakthrough when measuring ??65Cu on natural samples and NIST SRM 976 Cu isotope spiked with SO42- after both single anion column chromatography and double anion column chromatography. A set of five 100??g/L Cu SRM 976 samples spiked with 500mg/L SO42- resulted in an average ??65Cu of -3.50?????5.42??? following single anion column separation with variable SO42- breakthrough but an average concentration of 770??g/L. Following double anion column separation, the average SO42-concentration of 13??g/L resulted in better precision and accuracy for the measured ??65Cu value of 0.01?????0.02??? relative to the expected 0??? for SRM 976. We conclude that attention to SO42- breakthrough on sulfur-rich samples is necessary for accurate and precise measurements of ??65Cu and may require

  8. Sulfur Isotope Trends in Archean Microbialite Facies Record Early Oxygen Production and Consumption

    NASA Astrophysics Data System (ADS)

    Zerkle, A.; Meyer, N.; Izon, G.; Poulton, S.; Farquhar, J.; Claire, M.

    2014-12-01

    The major and minor sulfur isotope composition (δ34S and Δ33S) of pyrites preserved in ~2.65-2.5 billion-year-old (Ga) microbialites record localized oxygen production and consumption near the mat surface. These trends are preserved in two separate drill cores (GKF01 and BH1-Sacha) transecting the Campbellrand-Malmani carbonate platform (Ghaap Group, Transvaal Supergroup, South Africa; Zerkle et al., 2012; Izon et al., in review). Microbialite pyrites possess positive Δ33S values, plotting parallel to typical Archean trends (with a Δ33S/δ34S slope of ~0.9) but enriched in 34S by ~3 to 7‰. We propose that these 34S-enriched pyrites were formed from a residual pool of sulfide that was partially oxidized via molecular oxygen produced by surface mat-dwelling cyanobacteria. Sulfide, carrying the range of Archean Δ33S values, could have been produced deeper within the microbial mat by the reduction of sulfate and elemental sulfur, then fractionated upon reaction with O2 produced by oxygenic photosynthesis. Preservation of this positive 34S offset requires that: 1) sulfide was only partially (50­­-80%) consumed by oxidation, meaning H2S was locally more abundant (or more rapidly produced) than O2, and 2) the majority of the sulfate produced via oxidation was not immediately reduced to sulfide, implying either that the sulfate pool was much larger than the sulfide pool, or that the sulfate formed near the mat surface was transported and reduced in another part of the system. Contrastingly, older microbialite facies (> 2.7 Ga; Thomazo et al., 2013) appear to lack these observed 34S enrichments. Consequently, the onset of 34S enrichments could mark a shift in mat ecology, from communities dominated by anoxygenic photosynthesizers to cyanobacteria. Here, we test these hypotheses with new spatially resolved mm-scale trends in sulfur isotope measurements from pyritized stromatolites of the Vryburg Formation, sampled in the lower part of the BH1-Sacha core. Millimeter

  9. Sulfur isotope fractionation during growth of sulfate-reducing bacteria on various carbon sources

    NASA Astrophysics Data System (ADS)

    Kleikemper, Jutta; Schroth, Martin H.; Bernasconi, Stefano M.; Brunner, Benjamin; Zeyer, Josef

    2004-12-01

    Stable sulfur isotope fractionation during microbial sulfate reduction is a potential tool to estimate sulfate reduction rates at field sites. However, little is known about the influence of the utilized carbon source on the magnitude of sulfur isotope fractionation. To investigate this effect, both a pure culture (strain PRTOL1) and enrichment cultures from a petroleum hydrocarbon (PHC)-contaminated aquifer were used and grown in batch cultures on various carbon sources with an initial sulfate concentration of 1 mmol/L. As sole carbon sources the PHC components naphthalene, 1,3,5-trimethylbenzene, and heating oil (enrichment culture) and the organic acids acetate, pyruvate, benzoate, and 3-phenylpropionate (enrichment culture and PRTOL1) were used. Sulfate reduction rates of all cultures ranged from 6 ± 1 nmol cm -3 d -1 (enrichment culture grown on 1,3,5-trimethylbenzene) to 280 ± 6 nmol cm -3 d -1 (enrichment culture grown on pyruvate). Cell-specific sulfate reduction rates ranged from 1.1 × 10 -14 mol cell -1 d -1 (PRTOL1 grown on pyruvate) to 1.5 × 10 -13 mol cell -1 d -1 (PRTOL1 grown on acetate). Sulfur isotope enrichment factors (ɛ) for the enrichment culture ranged from 16.1‰ (3-phenylpropionate) to 34.5‰ (1,3,5-trimethylbenzene) and for PRTOL1 from 30.0‰ (benzoate) to 36.0‰ (pyruvate). Cultures of PRTOL1 always showed higher ɛ values than the enrichment culture when grown on the same carbon source due to culture-specific properties. Higher ɛ values were obtained when the enrichment culture was grown on PHC components than on organic acids. No relationship between ɛ values and cell-specific sulfate reduction rate existed when all data were combined. When comparing the magnitude of ɛ values determined in this laboratory study with ɛ values measured at contaminated and uncontaminated field sites, it becomes evident that a multitude of factors influences ɛ values at field sites and complicates their interpretation. The results of this study

  10. Simultaneous Analysis of Nitrogen, Carbon and Sulfur Stable Isotopes and Concentrations in Organics and Soils

    NASA Astrophysics Data System (ADS)

    Mambelli, S.; Brooks, P. D.; Sutka, R.; Hughes, S.; Finstad, K. M.; Pakes, M. J.; Dawson, T. E.

    2014-12-01

    To date, analysis of diet, food web complexities, biogeochemical cycles, and ecosystem functioning have largely focused on using variation in carbon (C) and nitrogen (N) stable isotope ratios. This is because a great deal is understood about what leads to this variation and because the dual stable isotope analysis of these two elements using continuous flow isotope ratio mass spectrometry (IRMS) is now commonplace. However, the aforementioned studies may all greatly benefit from the additional information one can get from also having sulfur (S) stable isotopes ratio data. Until very recently the analysis of δ34S has traditionally required an additional and often more difficult analytical procedure. Here, we report on the development of a new method that simultaneously analyzes the elemental and isotopic composition of N, C and S in a single sample. The new commercially available instrument includes a modified NCS elemental analyzer in line with an IRMS outfitted with 100 volt AD converters for wide dynamic range. We tested, and modified, this instrument to achieve maximum accuracy and precision for the isotopic measurements of all three elements. We found that the original design needed improvements to achieve our goals by: a) including a component (originally designed for trapping water) as buffer to reduce S memory and obtain reliable δ34S analysis; b) adding an external furnace for complete reduction of nitrogen oxides to N2 gas for accurate δ15N; c) adding a magnesium perchlorate water trap immediately after the reduction tube to minimize any water condensation that could also influence S memory. We analyzed a selection of organic materials and soils with approximately a 1:2 standards versus unknowns ratio per run. Using this NCS set-up, the precision of the N and C isotopic measurements was comparable to the one usually attained in NC mode alone (standard deviation of ± 0.13 δ15N in the range 30 to 400 µg N, and of ± 0.12 δ13C in the range 0.20 to 4 mg

  11. Sulfur isotopic fractionation in vacuum UV photodissociation of hydrogen sulfide and its potential relevance to meteorite analysis.

    PubMed

    Chakraborty, Subrata; Jackson, Teresa L; Ahmed, Musahid; Thiemens, Mark H

    2013-10-29

    Select meteoritic classes possess mass-independent sulfur isotopic compositions in sulfide and organic phases. Photochemistry in the solar nebula has been attributed as a source of these anomalies. Hydrogen sulfide (H2S) is the most abundant gas-phase species in the solar nebula, and hence, photodissociation of H2S by solar vacuum UV (VUV) photons (especially by Lyman-α radiation) is a relevant process. Because of experimental difficulties associated with accessing VUV radiation, there is a paucity of data and a lack of theoretical basis to test the hypothesis of a photochemical origin of mass-independent sulfur. Here, we present multiisotopic measurements of elemental sulfur produced during the VUV photolysis of H2S. Mass-independent sulfur isotopic compositions are observed. The observed isotopic fractionation patterns are wavelength-dependent. VUV photodissociation of H2S takes place through several predissociative channels, and the measured mass-independent fractionation is most likely a manifestation of these processes. Meteorite sulfur data are discussed in light of the present experiments, and suggestions are made to guide future experiments and models.

  12. Sulfur isotopic fractionation in vacuum UV photodissociation of hydrogen sulfide and its potential relevance to meteorite analysis

    PubMed Central

    Chakraborty, Subrata; Jackson, Teresa L.; Ahmed, Musahid; Thiemens, Mark H.

    2013-01-01

    Select meteoritic classes possess mass-independent sulfur isotopic compositions in sulfide and organic phases. Photochemistry in the solar nebula has been attributed as a source of these anomalies. Hydrogen sulfide (H2S) is the most abundant gas-phase species in the solar nebula, and hence, photodissociation of H2S by solar vacuum UV (VUV) photons (especially by Lyman-α radiation) is a relevant process. Because of experimental difficulties associated with accessing VUV radiation, there is a paucity of data and a lack of theoretical basis to test the hypothesis of a photochemical origin of mass-independent sulfur. Here, we present multiisotopic measurements of elemental sulfur produced during the VUV photolysis of H2S. Mass-independent sulfur isotopic compositions are observed. The observed isotopic fractionation patterns are wavelength-dependent. VUV photodissociation of H2S takes place through several predissociative channels, and the measured mass-independent fractionation is most likely a manifestation of these processes. Meteorite sulfur data are discussed in light of the present experiments, and suggestions are made to guide future experiments and models. PMID:23431159

  13. Sulfur isotopic fractionation in vacuum UV photodissociation of hydrogen sulfide and its potential relevance to meteorite analysis.

    PubMed

    Chakraborty, Subrata; Jackson, Teresa L; Ahmed, Musahid; Thiemens, Mark H

    2013-10-29

    Select meteoritic classes possess mass-independent sulfur isotopic compositions in sulfide and organic phases. Photochemistry in the solar nebula has been attributed as a source of these anomalies. Hydrogen sulfide (H2S) is the most abundant gas-phase species in the solar nebula, and hence, photodissociation of H2S by solar vacuum UV (VUV) photons (especially by Lyman-α radiation) is a relevant process. Because of experimental difficulties associated with accessing VUV radiation, there is a paucity of data and a lack of theoretical basis to test the hypothesis of a photochemical origin of mass-independent sulfur. Here, we present multiisotopic measurements of elemental sulfur produced during the VUV photolysis of H2S. Mass-independent sulfur isotopic compositions are observed. The observed isotopic fractionation patterns are wavelength-dependent. VUV photodissociation of H2S takes place through several predissociative channels, and the measured mass-independent fractionation is most likely a manifestation of these processes. Meteorite sulfur data are discussed in light of the present experiments, and suggestions are made to guide future experiments and models. PMID:23431159

  14. Sulfur isotope and trace element data from ore sulfides in the Noranda district (Abitibi, Canada): implications for volcanogenic massive sulfide deposit genesis

    NASA Astrophysics Data System (ADS)

    Sharman, Elizabeth R.; Taylor, Bruce E.; Minarik, William G.; Dubé, Benoît; Wing, Boswell A.

    2015-06-01

    We examine models for volcanogenic massive sulfide (VMS) mineralization in the ~2.7-Ga Noranda camp, Abitibi subprovince, Superior Province, Canada, using a combination of multiple sulfur isotope and trace element data from ore sulfide minerals. The Noranda camp is a well-preserved, VMS deposit-rich area that is thought to represent a collapsed volcanic caldera. Due to its economic value, the camp has been studied extensively, providing a robust geological framework within which to assess the new data presented in this study. We explore previously proposed controls on mineralization within the Noranda camp and, in particular, the exceptional Au-rich Horne and Quemont deposits. We present multiple sulfur isotope and trace element compositional data for sulfide separates representing 25 different VMS deposits and "showings" within the Noranda camp. Multiple sulfur isotope data for this study have δ34SV-CDT values of between -1.9 and +2.5 ‰, and Δ33SV-CDT values of between -0.59 and -0.03 ‰. We interpret the negative Δ33S values to be due to a contribution of sulfur that originated as seawater sulfate to form the ore sulfides of the Noranda camp VMS deposits. The contribution of seawater sulfate increased with the collapse and subsequent evolution of the Noranda caldera, an inference supported by select trace and major element analyses. In particular, higher concentrations of Se occur in samples with Δ33S values closer to 0 ‰, as well as lower Fe/Zn ratios in sphalerite, suggesting lower pressures and temperatures of formation. We also report a relationship between average Au grade and Δ33S values within Au-rich VMS deposits of the Noranda camp, whereby higher gold grades are associated with near-zero Δ33S values. From this, we infer a dominance of igneous sulfur in the gold-rich deposits, either leached from the volcanic pile and/or directly degassed from an associated intrusion.

  15. Sulfur isotope fractionation during oxidation of sulfur dioxide: gas-phase oxidation by OH radicals and aqueous oxidation by H2O2, O3 and iron catalysis

    NASA Astrophysics Data System (ADS)

    Harris, E.; Sinha, B.; Hoppe, P.; Crowley, J. N.; Ono, S.; Foley, S.

    2011-08-01

    The oxidation of SO2 to sulfate is a key reaction in determining the role of sulfate in the environment through its effect on aerosol size distribution and composition. Sulfur isotope analysis has been used to investigate sources and chemistry of sulfur dioxide and sulfate in the atmosphere, however interpretation of measured sulfur isotope ratios is challenging due to a lack of reliable information on the isotopic fractionation involved in major transformation pathways. This paper presents measurements of the fractionation factors for the major atmospheric oxidation reactions for SO2: Gas-phase oxidation by OH radicals, and aqueous oxidation by H2O2, O3 and a radical chain reaction initiated by iron. The measured fractionation factor for 34S/32S during the gas-phase reaction is αOH = (1.0089±0.0007) - ((4±5)×10-5) T(°C). The measured fractionation factor for 34S/32S during aqueous oxidation by H2O2 or O3 is αaq=(1.0167±0.0019) - ((8.7±3.5) ×10-5) T(°C). The observed fractionation during oxidation by H2O2 and O3 appeared to be controlled primarily by protonation and acid-base equilbria of S(IV) in solution, and there was no significant difference between the fractionation produced by the two oxidants within the experimental error. The isotopic fractionation factor from a radical chain reaction in solution catalysed by iron is αFe = (0.989±0.0043) at 19 °C for 34S/32S. Fractionation was mass-dependent with regards to 33S for all the reactions investigated. The radical chain reaction mechanism was the only measured reaction that had a faster rate for the light isotopes, and will be particularly useful to determine the importance of the transition-metal catalysed oxidation pathway.

  16. Sulfur isotope evidence for penetration of MVT fluids into igneous basement rocks, southeast Missouri, USA

    NASA Astrophysics Data System (ADS)

    Shelton, K. L.; Burstein, I. B.; Hagni, R. D.; Vierrether, C. B.; Grant, S. K.; Hennigh, Q. T.; Bradley, M. F.; Brandom, R. T.

    1995-08-01

    Previous studies of galena and sphalerite from Paleozoic MVT deposits in the Viburnum Trend, southeast Missouri documented large variations in δ34S values throughout the ore-forming event. The present study of Cu-Fe-sulfides reveals a similar δ34S variation that reflects two end-member sulfur reservoirs whose relative importance varied both temporally and spatially. More 34S-enriched sulfides (δ34S approaching 25‰) indicate introduction of sulfur from basinal sedimentary sources, whereas more 32S-enriched sulfides (δ34S < 5‰) may reflect fluids moving through underlying granitic basement. Two areas containing Precambrian, igneous-hosted FeCu mineralization in southeast Missouri (West and Central Domes of Boss-Bixby) were investigated to elucidate their relationship to Cu-rich MVT orebodies hosted nearby within the overlying Cambrian Bonneterre Dolomite. Mineralization at Boss-Bixby is composed of an early phase of iron oxide deposition followed by Cu-Fe-sulfides. The Central Dome is faulted and its mineralization is more fracture-controlled than the typically podiform ores of the West Dome. The δ34S values of West Dome sulfides are 0.9 to 6.5‰ and pyrite-chalcopyrite indicate a temperature of 525° ± 50 °C. These data indicate an igneous source of sulfur during Precambrian ore deposition. In contrast, δ34S values of Central Dome sulfides are 9.4 to 20.0‰ and pyrite-chalcopyrite indicate temperatures of 275° ± 50 °C. Similar δ34S values are obtained for chalcopyrite from the overlying MVT deposits. We speculate that deeply circulating, basin-derived MVT fluids mobilized sulfur and copper from the underlying igneous basement and redeposited them in overlying Curich MVT orebodies, as well as overprinting earlier Precambrian sulfides of the Central Dome with a later, Paleozoic MVT sulfur isotope signature. Many models for MVT fluid circulation in the Midcontinent region of North America assume that igneous basement rocks are an impermeable boundary

  17. Characterization of sulfur deposition over the period of industrialization in Japan using sulfur isotope ratio in Japanese cedar tree rings taken from stumps.

    PubMed

    Ishida, Takuya; Tayasu, Ichiro; Takenaka, Chisato

    2015-07-01

    We characterized the sulfur deposition history over the period of industrialization in Japan based on the sulfur isotope ratio (δ(34)S) in tree rings of Japanese cedar (Cryptomeria japonica D. Don) stumps. We analyzed and compared δ(34)S values in the rings from two types of disk samples from 170-year-old stumps that had been cut 5 years earlier (older forest stand) and from 40-year-old living trees (younger forest stand) in order to confirm the validity of using stump disks for δ(34)S analysis. No differences in δ(34)S values by age were found between the sample types, indicating that stump disks can be used for δ(34)S analysis. The δ(34)S profile in tree rings was significantly correlated with anthropogenic SO2 emissions in Japan (r = -0.76, p < 0.05) and, thus, tree rings serve as a record of anthropogenic sulfur emissions. In addition, the values did not change largely from pre-industrialization to the 1940s (+4.2 to +6.1‰). The values before the 1940s are expected to reflect the background sulfur conditions in Japan and, thus, disks containing rings formed before the 1940s contain information about the natural environmental sulfur, which is useful for biogeochemical studies.

  18. Microbial sulfate reduction within the Iheya North subseafloor hydrothermal system constrained by quadruple sulfur isotopes

    NASA Astrophysics Data System (ADS)

    Aoyama, Shinnosuke; Nishizawa, Manabu; Takai, Ken; Ueno, Yuichiro

    2014-07-01

    Subseafloor hydrothermal systems may host spatially extended and numerically abundant microbial communities sustained by sulfate reduction as one of the important terminal electron accepting metabolisms. In order to estimate microbial sulfate reduction in a subseafloor hydrothermal regime, we analyzed sulfur isotopes (S32/S33/S34/S36) of pore-water sulfate and mineralized sulfide in the upper 100 m of sedimentary sequences at the Iheya North hydrothermal field in the Okinawa Trough recovered in Integrated Ocean Drilling Program Expedition 331 (IODP Exp 331). On the basis of the pore water chemistry and temperature profiles, the subseafloor environment is divided into three hydrogeologic units. In the topmost Unit-1, relatively fresh seawater is recharged, and the bottommost Unit-3 is characterized by predominance of endmember-like high-temperature hydrothermal fluid (>300 °C) underlying the impermeable cap rock layers. Intermediate Unit-2 is subject to mixing between the hydrothermal fluid and seawater. The δ34S values of sulfate in the Unit-2 mixing zone were found to be more 34S-enriched than the values expected from simple mixing model of seawater sulfate in the Unit-1 with the hydrothermal fluid in the Unit-3. The observed SSO434-enrichment and sulfate concentration [SO2-4]-depletion suggest sulfate reduction is taking place below the seafloor. Based on our model calculation, the isotope discrimination (ε34) is estimated to be -21‰. This large isotope discrimination together with slight Δ33S‧ enrichment and Δ36S‧ depletion reveals that sulfate reduction is caused by microbial processes but not by thermochemical processes. In addition, our numerical simulation points out that sulfate may be reduced prior to presently undergoing mixing with high-temperature fluid, probably within the seawater recharge zone. Despite the abundant input of hydrothermal H2S, mineralized sulfide below 10 m seafloor (mbsf) shows characteristic sulfur isotopic signatures that

  19. Triple isotope composition of sulfur from sulfate on the MC-ICPMS Neptune

    NASA Astrophysics Data System (ADS)

    Paris, G.; Adkins, J. F.; Sessions, A. L.; Subhas, A.; Waldbauer, J.; Fischer, W. W.

    2011-12-01

    We present a new method to measure precise and accurate 34S/32S and 33S/32S ratios from small amounts of sulfate in solution. The sulfur cycle plays an important role in many earth system processes at a variety of timescales. Exploring the isotopic composition of sulfur from Carbonate Associated Sulfates (CAS) during geological times or from dissolved sulfate in modern seawater and porewater can provide important constraints on these processes. For carbonates, existing methods focus on samples rather rich in CAS (>100 ppm) or samples available in large amounts (>1g). Samples with either very low sulfate concentration (e.g., Archean-aged carbonates) and/or limited sample sizes (such as foraminifera) require a more sensitive analytical method. An attractive technique involves MC-ICPMS (multiCollector inductively-coupled plasma mass spectrometry), which has been used successfully for bulk and in-situ δ34S evaluation of sulfate and sulfide minerals (Craddock et al., 2008) and organic compounds (Amrani et al., 2009). Two main advantages of working with a MC-ICPMS (here a ThermoScientific Neptune) compared to conventional SO2 gas source mass spectrometry are an increased sensitivity and the ability to introduce sulfur as either sulfate or sulfide. However, this approach requires removal of the complex sample matrix so samples can be analyzed as sodium sulfate diluted in 5% HNO3. IAEA BaSO4 standards, on the other hand, can be run as dissolved BaSO4 through chelation of Ba with EDTA. Sample purification is achieved through Ca++ removal using either a cation-exchanging membrane or a micro-column of Dionex AG50X8 resin. These two methods allow exchange of Ca++ (or other cations) for H++. Sulfate can then be concentrated by evaporation for subsequent isotope analysis. The membrane is preferred for samples with sulfate concentrations lower than 100 ppm to decrease sulfur contamination from the AG50X8 sulfonyl groups and the resin is favored for samples with sulfate

  20. Identification of multiple sources of groundwater contamination by dual isotopes.

    PubMed

    Kaown, Dugin; Shouakar-Stash, Orfan; Yang, Jaeha; Hyun, Yunjung; Lee, Kang-Kun

    2014-01-01

    Chlorinated solvents are one of the most commonly detected groundwater contaminants in industrial areas. Identification of polluters and allocation of contaminant sources are important concerns in the evaluation of complex subsurface contamination with multiple sources. In recent years, compound-specific isotope analyses (CSIA) have been employed to discriminate among different contaminant sources and to better understand the fate of contaminants in field-site studies. In this study, the usefulness of dual isotopes (carbon and chlorine) was shown in assessments of groundwater contamination at an industrial complex in Wonju, Korea, where groundwater contamination with chlorinated solvents such as trichloroethene (TCE) and carbon tetrachloride (CT) was observed. In November 2009, the detected TCE concentrations at the study site ranged between nondetected and 10,066 µg/L, and the CT concentrations ranged between nondetected and 985 µg/L. In the upgradient area, TCE and CT metabolites were detected, whereas only TCE metabolites were detected in the downgradient area. The study revealed the presence of separate small but concentrated TCE pockets in the downgradient area, suggesting the possibility of multiple contaminant sources that created multiple comingling plumes. Furthermore, the variation of the isotopic (δ(13) C and δ(37) Cl) TCE values between the upgradient and downgradient areas lends support to the idea of multiple contamination sources even in the presence of detectable biodegradation. This case study found it useful to apply a spatial distribution of contaminants coupled with their dual isotopic values for evaluation of the contaminated sites and identification of the presence of multiple sources in the study area.

  1. SO2 in the Fall in the Arctic: Source Identification Using Sulfur Isotopes

    NASA Astrophysics Data System (ADS)

    Norman, A. L.; Seguin, A.; Rempillo, O. T.

    2011-12-01

    The Arctic atmosphere, although far from industrial sources, has a large anthropogenic SO2 load. Sulfur dioxide can have other sources including from dimethylsulphide (DMS) oxidation. One way to distinguish between these two types of SO2 is through sulfur isotope apportionment. During the Fall seasons of 2007 and 2008 aerosol sulfate and SO2 were measured at two sites in the Arctic. One site was on board the Canadian Coast Guard Ship, The Amundsen, as it traveled throughout the Arctic and the other site was at Alert, Nunavut, Canada. Sulfur dioxide concentrations at Alert varied between 0.02 and 18 nmol/m3 throughout the study with a median of 0.4 nmol/m3. δ34S values ranged between 0 and +11%. Concentrations and δ34S values aboard the Amundsen were much more diverse with concentrations ranging between 0.09 and 134 nmol/m3 (2007 median = 9.4 nmol/m3; 2008 median = 2.0 nmol/m3) and δ34S values ranging between -15 and +18%. High concentrations of SO2 on board the Amundsen were not directly from the Amundsen itself as there was no correlation with peaks in coincident CO2 measurements. Low concentrations of SO2 may, in a few instances, be associated with DMS oxidation. Negative δ34S values were present for samples collected near the Amundsen Gulf and are consistent with a third source of SO2 in the Arctic. This is likely the local source of SO2 from the Smoking Hills in the North West Territories. Distinguishing between these sources of SO2 in the Arctic and the importance of local verses regional sources will be discussed.

  2. Risk management for sulfur dioxide abatement under multiple uncertainties

    NASA Astrophysics Data System (ADS)

    Dai, C.; Sun, W.; Tan, Q.; Liu, Y.; Lu, W. T.; Guo, H. C.

    2016-03-01

    In this study, interval-parameter programming, two-stage stochastic programming (TSP), and conditional value-at-risk (CVaR) were incorporated into a general optimization framework, leading to an interval-parameter CVaR-based two-stage programming (ICTP) method. The ICTP method had several advantages: (i) its objective function simultaneously took expected cost and risk cost into consideration, and also used discrete random variables and discrete intervals to reflect uncertain properties; (ii) it quantitatively evaluated the right tail of distributions of random variables which could better calculate the risk of violated environmental standards; (iii) it was useful for helping decision makers to analyze the trade-offs between cost and risk; and (iv) it was effective to penalize the second-stage costs, as well as to capture the notion of risk in stochastic programming. The developed model was applied to sulfur dioxide abatement in an air quality management system. The results indicated that the ICTP method could be used for generating a series of air quality management schemes under different risk-aversion levels, for identifying desired air quality management strategies for decision makers, and for considering a proper balance between system economy and environmental quality.

  3. Sulfur and oxygen isotope tracing in zero valent iron based In situ remediation system for metal contaminants.

    PubMed

    Kumar, Naresh; Millot, Romain; Battaglia-Brunet, Fabienne; Négrel, Philippe; Diels, Ludo; Rose, Jérôme; Bastiaens, Leen

    2013-01-01

    In the present study, controlled laboratory column experiments were conducted to understand the biogeochemical changes during the microbial sulfate reduction. Sulfur and oxygen isotopes of sulfate were followed during sulfate reduction in zero valent iron incubated flow through columns at a constant temperature of 20±1°C for 90 d. Sulfur isotope signatures show considerable variation during biological sulfate reduction in our columns in comparison to abiotic columns where no changes were observed. The magnitude of the enrichment in δ(34)S values ranged from 9.4‰ to 10.3‰ compared to initial value of 2.3‰, having total fractionation δS between biotic and abiotic columns as much as 6.1‰. Sulfur isotope fractionation was directly proportional to the sulfate reduction rates in the columns. Oxygen isotopes in this experiment seem less sensitive to microbial activities and more likely to be influenced by isotopic exchange with ambient water. A linear relationship is observed between δ(34)S and δ(18)O in biotic conditions and we also highlight a good relationship between δ(34)S and sulfate reduction rate in biotic columns.

  4. Sulfur Isotopic Composition and Behavior in Granitoid Intrusions, southwestern New Brunswick, Canada

    NASA Astrophysics Data System (ADS)

    Yang, X.; Lentz, D. R.

    2004-05-01

    Bulk sulfur isotopic composition and sulfur content were determined for 12 granitoid intrusions (48 samples) associated with various types of mineralization (e.g., Au, Sb-W-Mo-Au, W-Sn-In-Zn-Pb-Cu) and the pertinent wallrocks (7 samples), in southwestern New Brunswick, Canada. This data together with data from field relations, magnetic susceptibility, sulfide mineralogy, petrology, and geochemistry, were used to characterize these intrusions. Two distinct groups can be established, although both show some features of I-type grantiods: (1) a Late Devonian granitic series (GS) including the Mount Pleasant, True Hill, Beech Hill, Pleasant Ridge, Kedron, Sorrel Ridge granites, and (2) a Late Silurian to Early Devonian granodioritic to monzogranitic series (GMS) including the Magaguadavic, Bocabec, Utopia, Tower Hill, Evandale, and Lake George intrusions. The former occur along the northwestern flank of the Saint George Batholith as satellite plutons, and the later form parts of this batholith and the Pokiok Batholith to the north. The GS rocks show the attributes of evolved I-type with some A-type features, whereas the GMS rocks are either reduced I-type (ilmenite-series), or normal I-type (magnetite-series). Strong assimilation and contamination by local metasedimentary rocks lead to the Tower Hill granite resembling S-type, e.g., the presence of muscovite and garnet. The GS type rocks have δ 34S values between -7.1 and +13 per mil with bulk-S content ranging from 33 to 3434 ppm. The GMS type rocks have relatively narrower variation in δ 34S values (-4.4 to +7.3 per mil), but with larger ranges of bulk-S content (45 to 11100 ppm). The granite samples with S contents much higher than its solubility in felsic melts are interpreted to be affected either by local metasedimentary rocks or by late stage hydrothermal alteration. The metasedimentary rocks contain variable S contents (707 to 14000 ppm) with δ 34S values of -10.6 to 0.1 per mil. In terms of mass balance, a

  5. On-line sulfur isotope analysis of organic material by direct combustion: Preliminary results and potential applications

    USGS Publications Warehouse

    Kester, C.L.; Rye, R.O.; Johnson, C.A.; Schwartz, C.H.; Holmes, C.H.

    2001-01-01

    Sulfur isotopes have received little attention in ecology studies because plant and animal materials typically have low sulfur concentrations (< 1 wt.%) necessitating labor-intensive chemical extraction prior to analysis. To address the potential of direct combustion of organic material in an elemental analyzer coupled with a mass spectrometer, we compared results obtained by direct combustion to results obtained by sulfur extraction with Eschka's mixture. Direct combustion of peat and animal tissue gave reproducibility of better than 0.5??? and on average, values are 0.8??? higher than values obtained by Eschka extraction. Successful direct combustion of organic material appears to be a function of sample matrix and sulfur concentration. Initial results indicate that direct combustion provides fast, reliable results with minimal preparation. Pilot studies underway include defining bear diets and examining fluctuations between freshwater and brackish water in coastal environments.

  6. Sulfur isotope fractionation during oxidation of sulfur dioxide: gas-phase oxidation by OH radicals and aqueous oxidation by H2O2, O3 and iron catalysis

    NASA Astrophysics Data System (ADS)

    Harris, E.; Sinha, B.; Hoppe, P.; Crowley, J. N.; Ono, S.; Foley, S.

    2012-01-01

    The oxidation of SO2 to sulfate is a key reaction in determining the role of sulfate in the environment through its effect on aerosol size distribution and composition. Sulfur isotope analysis has been used to investigate sources and chemical processes of sulfur dioxide and sulfate in the atmosphere, however interpretation of measured sulfur isotope ratios is challenging due to a lack of reliable information on the isotopic fractionation involved in major transformation pathways. This paper presents laboratory measurements of the fractionation factors for the major atmospheric oxidation reactions for SO2: Gas-phase oxidation by OH radicals, and aqueous oxidation by H2O2, O3 and a radical chain reaction initiated by iron. The measured fractionation factor for 34S/32S during the gas-phase reaction is αOH = (1.0089±0.0007)-((4±5)×10-5) T(°C). The measured fractionation factor for 34S/32S during aqueous oxidation by H2O2 or O3 is αaq = (1.0167±0.0019)-((8.7±3.5) ×10-5)T(°C). The observed fractionation during oxidation by H2O2 and O3 appeared to be controlled primarily by protonation and acid-base equilibria of S(IV) in solution, which is the reason that there is no significant difference between the fractionation produced by the two oxidants within the experimental error. The isotopic fractionation factor from a radical chain reaction in solution catalysed by iron is αFe = (0.9894±0.0043) at 19 °C for 34S/32S. Fractionation was mass-dependent with regards to 33S/32S for all the reactions investigated. The radical chain reaction mechanism was the only measured reaction that had a faster rate for the light isotopes. The results presented in this study will be particularly useful to determine the importance of the transition metal-catalysed oxidation pathway compared to other oxidation pathways, but other main oxidation pathways can not be distinguished based on stable sulfur isotope measurements alone.

  7. High-resolution (SIMS) versus bulk sulfur isotope patterns of pyrite in Proterozoic microbialites with diverse mat textures

    NASA Astrophysics Data System (ADS)

    Gomes, M. L.; Fike, D. A.; Bergmann, K.; Knoll, A. H.

    2015-12-01

    Sulfur (S) isotope signatures of sedimentary pyrite preserved in marine rocks provide a rich suite of information about changes in biogeochemical cycling associated with the evolution of microbial metabolisms and oxygenation of Earth surface environments. Conventionally, these S isotope records are based on bulk rock measurements. Yet, in modern microbial mat environments, S isotope compositions of sulfide can vary by up to 40‰ over a spatial range of ~ 1 mm. Similar ranges of S isotope variability have been found in Archean pyrite grains using both Secondary Ion Mass Spectrometry and other micro-analytical techniques. These micron-scale patterns have been linked to changes in rates of microbial sulfate reduction and/or sulfide oxidation, isotopic distillation of the sulfate reservoir due to microbial sulfate reduction, and post-depositional alteration. Fine-scale mapping of S isotope compositions of pyrite can thus be used to differentiate primary environmental signals from post-depositional overprinting - improving our understanding of both. Here, we examine micron-scale S isotope patterns of pyrite in microbialites from the Mesoproterozoic-Neoproterozoic Sukhaya Tunguska Formation and Neoproterozoic Draken Formation in order to explore S isotope variability associated with different mat textures and pyrite grain morphologies. A primary goal is to link modern observations of how sulfide spatial isotope distributions reflect active microbial communities present at given depths in the mats to ancient processes driving fine-sale pyrite variability in microbialites. We find large (up to 60‰) S isotope variability within a spatial range of less than 2.5cm. The micron-scale S isotope measurements converge around the S isotope composition of pyrite extracted from bulk samples of the same microbialites. These micron-scale pyrite S isotope patterns have the potential to reveal important information about ancient biogeochemical cycling in Proterozoic mat environments

  8. Compound-specific sulfur isotope analysis of thiadiamondoids of oils from the Smackover Formation, USA

    USGS Publications Warehouse

    Zvi Gvirtzman,; Ward Said-Ahmad,; Ellis, Geoffrey S.; Ronald J. Hill,; J. Michael Moldowan,; Zhibin Wei,; Alon Amrani,

    2015-01-01

    Thiadiamondoids (TDs) are diamond-like compounds with a sulfide bond located within the cage structure. These compounds were suggested as a molecular proxy for the occurrence and extent of thermochemical sulfate reduction (TSR). Compound-specific sulfur-isotope analysis of TDs may create a multi-parameter system, based on molecular and δ34S values that may be sensitive over a wider range of TSR and thermal maturation stages. In this study, we analyzed a suite of 12 Upper Jurassic oil and condensate samples generated from source rocks in the Smackover Formation to perform a systematic study of the sulfur isotope distribution in thiadiamondoids (one and two cages). For comparison we measured the δ34S composition of benzothiophenes (BTs) and dibenzothiophenes (DBTs). We also conducted pyrolysis experiments with petroleum and model compounds to have an insight into the formation mechanisms of TDs. The δ34S of the TDs varied significantly (ca 30‰) between the different oils depending on the degree of TSR alteration. The results showed that within the same oil, the one-cage TDs were relatively uniform, with 34S enriched values similar to those of the coexisting BTs. The two-cage TDs had more variable δ34S values that range from the δ34S values of BTs to those of the DBTs, but with general 34S depletion relative to one cage TDs. Hydrous pyrolysis experiments (360 °C, 40 h) with either CaSO4 or elemental S (equivalent S molar concentrations) and adamantane as a model compound demonstrate the formation of one cage TDs in relatively low yields (<0.2%). Higher concentrations of TDs were observed in the elemental sulfur experiments, most likely because of the higher rates of reaction with adamantane under these experimental conditions. These results show that the formation of TDs is not exclusive to TSR reactions, and that they can also form by reaction with reduced S species apart from sulfate reduction, though at low yields. Oxygenated compounds, most notably 2

  9. Compound-specific sulfur isotope analysis of thiadiamondoids of oils from the Smackover Formation, USA

    NASA Astrophysics Data System (ADS)

    Gvirtzman, Zvi; Said-Ahmad, Ward; Ellis, Geoffrey S.; Hill, Ronald J.; Moldowan, J. Michael; Wei, Zhibin; Amrani, Alon

    2015-10-01

    Thiadiamondoids (TDs) are diamond-like compounds with a sulfide bond located within the cage structure. These compounds were suggested as a molecular proxy for the occurrence and extent of thermochemical sulfate reduction (TSR). Compound-specific sulfur-isotope analysis of TDs may create a multi-parameter system, based on molecular and δ34S values that may be sensitive over a wider range of TSR and thermal maturation stages. In this study, we analyzed a suite of 12 Upper Jurassic oil and condensate samples generated from source rocks in the Smackover Formation to perform a systematic study of the sulfur isotope distribution in thiadiamondoids (one and two cages). For comparison we measured the δ34S composition of benzothiophenes (BTs) and dibenzothiophenes (DBTs). We also conducted pyrolysis experiments with petroleum and model compounds to have an insight into the formation mechanisms of TDs. The δ34S of the TDs varied significantly (ca 30‰) between the different oils depending on the degree of TSR alteration. The results showed that within the same oil, the one-cage TDs were relatively uniform, with 34S enriched values similar to those of the coexisting BTs. The two-cage TDs had more variable δ34S values that range from the δ34S values of BTs to those of the DBTs, but with general 34S depletion relative to one cage TDs. Hydrous pyrolysis experiments (360 °C, 40 h) with either CaSO4 or elemental S (equivalent S molar concentrations) and adamantane as a model compound demonstrate the formation of one cage TDs in relatively low yields (<0.2%). Higher concentrations of TDs were observed in the elemental sulfur experiments, most likely because of the higher rates of reaction with adamantane under these experimental conditions. These results show that the formation of TDs is not exclusive to TSR reactions, and that they can also form by reaction with reduced S species apart from sulfate reduction, though at low yields. Oxygenated compounds, most notably 2

  10. Determination of sulfur in biodiesel microemulsions using the summation of the intensities of multiple emission lines.

    PubMed

    Young, Carl G; Amais, Renata S; Schiavo, Daniela; Garcia, Edivaldo E; Nóbrega, Joaquim A; Jones, Bradley T

    2011-05-15

    A method for the determination of sulfur in biodiesel samples by inductively coupled plasma optical emission spectrometry which uses microemulsion for sample preparation and the summation of the intensities of multiple emission lines has been developed. Microemulsions were prepared using 0.5 mL of 20% v/v HNO(3), 0.5 mL of Triton X-100, 2-3 mL of biodiesel sample, and diluted with n-propanol to a final volume of 10 mL. Summation of the emission intensities of multiple sulfur lines allowed for increased accuracy and sensitivity. The amounts of sulfur determined experimentally were between 2 and 7 mg L(-1), well below legislative standards for many countries. Recoveries obtained ranged from 72 to 119%, and recoveries obtained for the 182.562 nm line were slightly lower. This is most likely due to its lower sensitivity. Using microemulsion for sample preparation and the summation of the intensities of multiple emission lines for the successful determination of sulfur in biodiesel has been demonstrated. PMID:21482315

  11. Recycling of water, carbon, and sulfur during subduction of serpentinites: A stable isotope study of Cerro del Almirez, Spain

    USGS Publications Warehouse

    Alt, Jeffrey C.; Garrido, Carlos J.; Shanks, Wayne C.; Turchyn, Alexandra; Padrón-Navarta, José Alberto; López Sánchez-Vizcaíno, Vicente; Gómez Pugnaire, María Teresa; Marchesi, Claudio

    2012-01-01

    We use the concentrations and isotope compositions of water, carbon, and sulfur in serpentinites and their dehydration products to trace the cycling of volatiles during subduction. Antigorite serpentinites from the Cerro del Almirez complex, Spain, contain 9–12 wt.% H2O and 910 ± 730 ppm sulfur, and have bulk δ18O values of 8.6 ± 0.4‰, δD = − 54 ± 5‰, and δ34S = 5.0‰, consistent with serpentinization at temperatures of ~ 200 °C by seawater hydrothermal fluids in a seafloor setting. The serpentinites were dehydrated to chlorite–harzburgite (olivine + orthopyroxene + chlorite) at 700 °C and 1.6–1.9 GPa during subduction metamorphism, resulting in loss of water, and sulfur. The chlorite–harzburgites contain 5.7 ± 1.9 wt.% H2O, and have bulk δ18O = 8.0 ± 0.9‰, and δD = − 77 ± 11‰. The rocks contain 650 ± 620 ppm sulfur having δ34S = 1.2‰. Dehydration of serpentinite resulted in loss of 5 wt.% H2O having δ18O = 8–10‰ and δD = − 27 to − 65‰, and loss of 260 ppm sulfur as sulfate, having δ34S = 14.5‰. The contents and δ13C of total carbon in the two rock types overlap, with a broad trend of decreasing carbon contents and δ13C from ~ 1300 to 200 ppm and − 9.6 to − 20.2‰. This reflects mixing between reduced carbon in the rocks (210 ppm, δ13C ≈ − 26‰) and seawater-derived carbonate (δ13C ≈ − 1‰). Our results indicate: 1) Serpentinized oceanic peridotites carry significant amounts of isotopically fractionated water, carbon and sulfur into subduction zones; 2) Subduction of serpentinites to high P and T results in loss of water, and sulfur, which can induce melting and contribute to 18O, D, and 34S enrichments and oxidation of the sub-arc mantle wedge; and 3) Isotopically fractionated water, carbon, and sulfur in serpentinite dehydration products are recycled deeper into the mantle where they can contribute to isotope heterogeneities and may be significant for volatile budgets of the deep Earth.

  12. Evaluation of the 34S/32S ratio of Soufre de Lacq elemental sulfur isotopic reference material by continuous flow isotope-ratio mass spectrometry

    USGS Publications Warehouse

    Qi, H.P.; Coplen, T.B.

    2003-01-01

    Soufre de Lacq elemental sulfur reference material (IAEA-S-4) isotopically is homogeneous in amounts as small as 41 ??g as determined by continuous flow isotope-ratio mass spectrometry. The ??34S value for this reference material is +16.90 ?? 0.12??? (1??) on a scale (Vienna Can??on Diablo troilite, VCDT) where IAEA-S-1 Ag2S is -0.3??? and IAEA-S-2 Ag2S is +22.67???. Published by Elsevier Science B.V.

  13. The age curves of sulfur and oxygen isotopes in marine sulfate and their mutual interpretation

    USGS Publications Warehouse

    Claypool, George E.; Holser, William T.; Kaplan, Isaac R.; Sakai, Hitoshi; Zak, Israel

    1980-01-01

    Three hundred new samples of marine evaporite sulfate, of world-wide distribution, were analyzed for δ34S, and 60 of these also for δ18O in the sulfate ion. Detailed δ34S age curves for Tertiary—Cretaceous, Permian—Pennsylvanian, Devonian, Cambrian and Proterozoic times document large variations in δ34S. A summary curve forδ18O also shows definite variations, some at different times than δ34S, and always smaller. The measured δ34S and δ18O correspond to variations in these isotopes in sulfate of the world ocean surface. The variations of δ18O are controlled by input and output fluxes of sulfur in the ocean, three of which are the same that control δ34S: deposition and erosion of sulfate, and deposition of sulfide. Erosion of sulfide differs in its effect on the S and O systems. δ18O in the sulfate does not seem to be measurably affected by equilibration with either seawater or with subsurface waters after crystallization. In principle, the simultaneous application of both δ34S and δ18O age curves should help reduce the number of assumptions in calculations of the cycles of sulfur and oxygen through geological time, and a new model involving symmetrical fluxes is introduced here to take advantage of the oxygen data. However, all previously published models as well as this one lead to anomalies, such as unreasonable calcium or oxygen depletions in the ocean—atmosphere system. In addition, most models are incapable of reproducing the sharp rises of the δ34S curve in the late Proterozoic, the Devonian and the Triassic which would be the result of unreasonably fast net sulfide deposition. This fast depletion could result from an ocean that has not always been mixed (as previously assumed in all model calculations).

  14. Biogeochemical cycling of arsenic in coastal salinized aquifers: Evidence from sulfur isotope study.

    PubMed

    Kao, Yu-Hsuan; Wang, Sheng-Wei; Liu, Chen-Wuing; Wang, Pei-Ling; Wang, Chung-Ho; Maji, Sanjoy Kumar

    2011-10-15

    Arsenic (As) contamination of groundwater, accompanied by critical salinization, occurs in the southwestern coastal area of Taiwan. Statistical analyses and geochemical calculations indicate that a possible source of aqueous arsenic is the reductive dissolution of As-bearing iron oxyhydroxides. There are few reports of the influence of sulfate-sulfide redox cycling on arsenic mobility in brackish groundwater. We evaluated the contribution of sulfate reduction and sulfide re-oxidation on As enrichment using δ(34)S([SO(4)]) and δ(18)O([SO(4)]) sulfur isotopic analyses of groundwater. Fifty-three groundwater samples were divided into groups of high-As content and salinized (Type A), low-As and non-salinized (Type B), and high-As and non-salinized (Type C) groundwaters, based on hydro-geochemical analysis. The relatively high enrichment of (34)S([SO(4)]) and (18)O([SO(4)]) present in Type A, caused by microbial-mediated reduction of sulfate, and high (18)O enrichment factor (ε([SO(4)-H(2)O])), suggests that sulfur disproportionation is an important process during the reductive dissolution of As-containing iron oxyhydroxides. Limited co-precipitation of ion-sulfide increased the rate of As liberation under anaerobic conditions. In contrast to this, Type B and Type C groundwater samples showed high δ(18)O([SO(4)]) and low δ(34)S([SO(4)]) values under mildly reducing conditions. Base on (18)O mass balance calculations, the oxide sources of sulfate are from infiltrated atmospheric O(2), caused by additional recharge of dissolved oxygen and sulfide re-oxidation. The anthropogenic influence of extensive pumping also promotes atmospheric oxygen entry into aquifers, altering redox conditions, and increasing the rate of As release into groundwater.

  15. Thermal neutron capture gamma rays from sulfur isotopes: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Raman, S.; Carlton, R. F.; Wells, J. C.; Jurney, E. T.; Lynn, J. E.

    1985-07-01

    We have carried out a systematic investigation of γ rays after thermal neutron capture by all stable sulfur isotopes (32S, 33S, 34S, and 36S). The measurements were made at the internal target facility at the Los Alamos Omega West Reactor. We detected a larger number of γ rays: ~100 in 33S, ~270 in 34S, ~60 in 35S, and ~15 in 37S. Before developing detailed level schemes, we culled and then consolidated the existing information on energies and Jπ values for levels of these nuclides. Based on the current data, we have constructed detailed decay schemes, which imply that there are significant populations of 26 excited states in 33S, 70 states in 34S, 20 states in 35S, and 7 states in 37S. By checking the intensity balance for these levels and by comparing the total intensity of primary transitions with the total intensity of secondary γ rays feeding the ground state, we have demonstrated the relative completeness of these decay schemes. For strongly populated levels, the branching ratios based on the current measurements are generally better than those available from previous measurements. In all four cases, a few primary electric dipole (E1) transitions account for a large fraction of the capture cross section for that particular nuclide. To understand and explain these transitions, we have recapitulated and further developed the theory of potential capture. Toward this end, we reviewed the theory relating off-resonance neutron capture to the optical-model capture. We studied a range of model-dependent effects (nature and magnitude of imaginary potential, surface diffuseness, etc.) on the potential capture cross section, and we have shown how experimental data may be analyzed using the expression for channel capture suitably modified by a factor that takes into account the model-dependent effects. The calculations of cross sections for most of the primary transitions in the sulfur isotopes are in good agreement with the data. Some discrepancies for weaker

  16. Coupled iron, sulfur and carbon isotope evidences for arsenic enrichment in groundwater

    NASA Astrophysics Data System (ADS)

    Wang, Yanxin; Xie, Xianjun; Johnson, Thomas M.; Lundstrom, Craig C.; Ellis, Andre; Wang, Xiangli; Duan, Mengyu; Li, Junxia

    2014-11-01

    It is generally accepted that microbial processes play a key role in the mobilization and enrichment of arsenic (As) in groundwater. However, the detailed mechanism of the metabolic processes remain poorly understand. We apply isotopic measurements of iron (δ56Fe vs. IRMM-14), sulfur (δ34SSO4 vs. V-CDT) and carbon (δ13CDIC vs. V-PDB) to an experimental field plot in the Datong Basin, northern China. An array of monitoring wells was installed in a ≈1700-m2 plot in which high concentrations of As, ranging from 4.76 to 469.5 μg/L, were detected in the groundwater. The measured range of δ34SSO4 values from 10.0‰ to 24.7‰ indicates the prevalence of microbial sulfate reduction within aquifers. The range of δ56Fe values measured in the groundwater suggests microbial Fe(III) reduction and the occurrence of isotopic exchange between Fe(II)aq and FeS precipitation. The low δ13CDIC values (up to -33.6‰) measured in groundwater are evidences for the microbial oxidation of organic matter, which is interpreted as the light carbon pool within the aquifer sediments. The high As (As > 50 μg/L) groundwater, which has higher δ34SSO4 and δ56Fe values and lower δ13C values, indicates the following: (1) microbial reduction of sulfate causes the mobilization of As through HS- abiotic reduction of Fe(III) minerals and/or formation of As-sulfur components; and (2) direct microbial reduction of Fe(III) oxides, hydroxides and oxyhydroxides cannot increase As concentrations to greater than 50 μg/L. Re-oxidation of Fe-sufide explains how sample C1-2 can have a high As concentration and low δ34SSO4 and high δ56Fe values. The results provide new insight into the mechanism of As enrichment in groundwater.

  17. Biogeochemical cycling in an organic-rich coastal marine basin. 8. A sulfur isotopic budget balanced by differential diffusion across the sediment-water interface

    USGS Publications Warehouse

    Chanton, J.P.; Martens, C.S.; Goldhaber, M.B.

    1987-01-01

    The sulfur isotopic composition of the sulfur fluxes occurring in the anoxic marine sediments of Cape Lookout Bight, N.C., U.S.A., was determined, and the result of isotopic mass balance was obtained via the differential diffusion model. Seasonal pore water sulfate ??34S measurements yielded a calculated sulfate input of 0.6%.. Sulfate transported into the sediments via diffusion appeared to be enriched in the lighter isotope because its concentration gradient was steeper, due to the increase in the measured isotopic composition of sulfate with depth. Similarly, the back diffusion of dissolved sulfide towards the sediment-water interface appeared enriched in the heavier isotope. The isotopic composition of this flux was calculated from measurements of the ??34S of dissolved sulfide and was determined to be 15.9%.. The isotopic composition of buried sulfide was determined to be -5.2%. and the detrital sulfur input was estimated to be -6.2%.. An isotope mass balance equation based upon the fluxes at the sediment-water interface successfully predicted the isotopic composition of the buried sulfur flux within 0.5%., thus confirming that isotopes diffuse in response to their individual concentration gradients. ?? 1987.

  18. Carbon isotope ratios of Phanerozoic marine cements: Re-evaluating the global carbon and sulfur systems

    NASA Astrophysics Data System (ADS)

    Carpenter, Scott J.; Lohmann, Kyger C.

    1997-11-01

    Original δ 13C values of abiotically precipitated marine cements from a variety of stratigraphic intervals have been used to document secular variations in the δ 13C values of Phanerozoic oceans. These, together with the ° 34S values of coeval marine sulfates, are used to examine the global cycling of carbon and sulfur. It is generally accepted that secular variation in δ 13C and δ 34S values of marine carbonates and sulfates is controlled by balanced oxidation-reduction reactions and that their long-term, steady-state variation can be predicted from the present-day isotopic fractionation ratio (Δ c/Δ s) the ratio of the riverine flux of sulfur and carbon ( Fs/ Fc). The predicted slope of the linear relation between δ 13C carb and δ 34S sulfate values is approximately -0.10 to -0.14. However, temporal variation observed in marine cement δ 13C values and the 6345 values of coeval marine sulfates produces a highly significant linear relation ( r2 = 0.80; α > 95%) with a slope of -0.24; approximately twice the predicted value. This discordance suggests that either the Phanerozoic average riverine Fs/ Fc was 1.6-3.3 times greater than today's estimates or that an additional source of 34S-depleted sulfur or 13C-enriched carbon, other than continental reservoirs, was active during the Phanerozoic. This new relation between marine δ 13C and δ 34S values suggests that the flux of reduced sulfur, iron, and manganese from seafloor hydrothermal systems affects oceanic O2 levels which, in turn, control the oxidation or burial of organic matter, and thus the δ 13C value of marine DIC. Therefore, the sulfur system (driven by seafloor hydrothermal systems) controls the carbon system rather than organic carbon burial controlling the response of δ 34S values (via formation of sedimentary pyrite). Secular variation of marine 87Sr/86Sr ratios and δ 13C values argues for a coupling of δ 34S and δ 34S values to variation in the relative contribution of seafloor

  19. High-precision sulfur isotope composition of enstatite meteorites and implications of the formation and evolution of their parent bodies

    NASA Astrophysics Data System (ADS)

    Defouilloy, C.; Cartigny, P.; Assayag, N.; Moynier, F.; Barrat, J.-A.

    2016-01-01

    In order to better understand the formation and evolution of their parent bodies, the three isotope ratios of sulfur were analyzed in 33 enstatite meteorites (24 enstatite chondrites and 9 aubrites). The results show that on average all enstatite chondrite groups are enriched in the lightest isotopes compared to other chondrite groups, with means of δ34S of -0.28 ± 0.22‰ for EH3/4, -0.16 ± 0.16‰ for EH5, -0.32 ± 0.15‰ for EL3, -0.67 ± 0.16‰ for EL6 and -0.64 ± 0.00‰ for EL7 (all 1σ). Aubrites show a larger isotope variability in their composition, with a δ34S varying from -1.350‰ to +0.154‰. Contrary to previously published results, our data show a distinct composition for EL6 compared to other enstatite chondrites. This could be related to an impact-induced loss of isotopically heavy oldhamite (δ34S = by 3.62 ± 3.02‰ (1σ)) on the EL parent body. Although the bulk sulfur in both enstatite meteorites and aubrites does not show any significant Δ33S and Δ36S, the oldhamite fraction shows clear evidence of mass independent fractionation on the 36S/32S ratio (in 3 out of 9 analyzes, Δ36S up to +2.2‰), a signal that is not correlated to any 33S/32S anomaly (in 1 out of 9 analyzes, Δ33S down to -0.085‰). Though a nebular or photochemical origin cannot be ruled out, the most plausible mechanism to produce such isolated non-mass dependent 36S/32S anomalies would be a contribution of FeCl2 containing excesses of 36S due to the decay of 36Cl to the leached oldhamite fraction. Even though the sulfur isotopic composition measured in enstatite meteorites is distinct from the Bulk Silicate Earth (BSE), the isotopically lightest samples of EL6, EL7 and aubrites are approaching the isotopic composition of the BSE and enstatite meteorites remain the meteorites with the sulfur isotopic composition the closest to the terrestrial one.

  20. Use of isotopic sulfur to determine whitebark pine consumption by Yellowstone bears: a reassessment

    USGS Publications Warehouse

    Schwartz, Charles C.; Teisberg, Justin E.; Fortin, Jennifer K.; Haroldson, Mark A.; Servheen, Christopher; Robbins, Charles T.; van Manen, Frank T.

    2014-01-01

    Use of naturally occurring stable isotopes to estimate assimilated diet of bears is one of the single greatest breakthroughs in nutritional ecology during the past 20 years. Previous research in the Greater Yellowstone Ecosystem (GYE), USA, established a positive relationship between the stable isotope of sulfur (δ34S) and consumption of whitebark pine (Pinus albicaulis) seeds. That work combined a limited sample of hair, blood clots, and serum. Here we use a much larger sample to reassess those findings. We contrasted δ34S values in spring hair and serum with abundance of seeds of whitebark pine in samples collected from grizzly (Ursus arctos) and American black bears (U. americanus) in the GYE during 2000–2010. Although we found a positive relationship between δ34S values in spring hair and pine seed abundance for grizzly bears, the coefficients of determination were small (R2 ≤ 0.097); we failed to find a similar relationship with black bears. Values of δ34S in spring hair were larger in black bears and δ34S values in serum of grizzly bears were lowest in September and October, a time when we expect δ34S to peak if whitebark pine seeds were the sole source of high δ34S. The relationship between δ34S in bear tissue and the consumption of whitebark pine seeds, as originally reported, may not be as clean a method as proposed. Data we present here suggest other foods have high values of δ34S, and there is spatial heterogeneity affecting the δ34S values in whitebark pine, which must be addressed.

  1. Sulfur and oxygen isotopic systematics of the 1982 eruptions of El Chichón Volcano, Chiapas, Mexico

    NASA Astrophysics Data System (ADS)

    Rye, R. O.; Luhr, J. F.; Wasserman, M. D.

    1984-12-01

    Thermometers based on sulfur and oxygen isotopic compositions of anhydrite, pyrrhotite, titanomagnetite, and plagioclase crystals from fresh pumices of the 1982 eruptions of El Chichón Volcano indicate a pre-eruption temperature of 810 ± 40°C, confirming textural evidence that the anhydrite precipitated directly from the melt. The isotopic composition of sulfate leached from fresh ashfall samples shows it to be a mixture of anhydrite microphenocrysts and adsorbed sulfate derived from oxidized sulfur (SO 2) in the eruption plume. The leachate data show no evidence for rapid oxidation of significant amounts of H 2S in the eruption cloud even though the fugacity ratio of H 2S/SO 2 in the gas phase of the magma was >400. This may indicate kinetic inhibition of H 2S to SO 2 conversion in the eruption cloud. Prior to eruption, the magma contained an estimated 2.6 wt. % sulfur (as SO 3). The estimated δ 34S of the bulk magma is 5.8‰. Such a high value may reflect assimilation of 34S-enriched evaporites or the prior loss of 34S-depleted H 2S to a fluid or gas phase during formation of a small prophyry-type hydrothermal system or ore deposit. In either case, the original magma must have been very sulfur rich. It is likely that the initial high sulfur content of the magma and at least some of its 34S enrichment reflects involvement of subducted volcanogenic massive sulfides deposits during Benioff-zone partial melting. Isotopic data on mineralized, accidental lithic fragments support the possible development of a porphyry-type system at El Chichón.

  2. Ecologically and Geologically Relevant Isotope Signatures of C, N, and S in Okenone Producing Purple Sulfur Bacteria

    NASA Astrophysics Data System (ADS)

    Smith, D.; Steele, A.; Bowden, R.; Fogel, M. L.

    2013-12-01

    The carbon (C), nitrogen (N), and sulfur (S) cycles are linked in euxinic environments by purple sulfur bacteria (PSB). PSB could be responsible for the isotopic enrichments that have been observed in both fresh and marine anoxic basins. Okenane, the only recognized molecular fossil unique to PSB, is derived from okenone, a carotenoid pigment unique to Chromatiaceae. Since PSB have this exclusive molecular fossil and are fundamental components in the overall ecology of euxinic environments, a comprehensive study was undertaken to assess the C, N, and S metabolisms PSB carryout under precise laboratory conditions. The consequential isotopic fractionations that may be documented in modern environments and geologic record were examined. Autotrophic cultures of Marichromatium purpuratum DSMZ 1591 (Mpurp1591) were observed to have a fractionation between CO2 and biomass (Δ13Cbiomass - CO2), ranging from -16.1 to -37.6‰, dependent on growth stage. This rather large range of CO2 fractionation expands previously reported values for RuBisCO in PSB. Ammonium assimilation, controlled by glutamate dehydrogenase, was shown to have a fractionation (Δ15Nbiomass - NH4) of -15‰ in autotrophic cultures of Mpurp1591 and Thiocapsa marina 5653, documented for the first time in PSB. While it has been previously shown that phototrophic sulfur oxidizing bacteria connect sulfur and carbon cycling in euxinic ecosystems, the percentage of elemental sulfur and bulk biomass δ34S values of Mpurp1591 cells were contingent upon their carbon metabolisms. Here we show that the isotopic enrichments of S and N observed in freshwater and marine anoxic basins could be explained by the prevalence of PSB.

  3. Sulfur and oxygen isotopic systematics of the 1982 eruptions of El Chichón Volcano, Chiapas, Mexico

    USGS Publications Warehouse

    Rye, R.O.; Luhr, J.F.; Wasserman, M.D.

    1984-01-01

    Thermometers based on sulfur and oxygen isotopic compositions of anhydrite, pyrrhotite, titanomagnetite, and plagioclase crystals from fresh pumices of the 1982 eruptions of El Chichón Volcano indicate a pre-eruption temperature of 810 ± 40°C, confirming textural evidence that the anhydrite precipitated directly from the melt. The isotopic composition of sulfate leached from fresh ashfall samples shows it to be a mixture of anhydrite microphenocrysts and adsorbed sulfate derived from oxidized sulfur (SO2) in the eruption plume. The leachate data show no evidence for rapid oxidation of significant amounts of H2S in the eruption cloud even though the fugacity ratio of H2S/SO2 in the gas phase of the magma was >400. This may indicate kinetic inhibition of H2S to SO2 conversion in the eruption cloud. Prior to eruption, the magma contained an estimated 2.6 wt. % sulfur (as SO3). The estimated δ 34S of the bulk magma is 5.8‰. Such a high value may reflect assimilation of 34S-enriched evaporites or the prior loss of 34S-depleted H2S to a fluid or gas phase during formation of a small prophyry-type hydrothermal system or ore deposit. In either case, the original magma must have been very sulfur rich. It is likely that the initial high sulfur content of the magma and at least some of its 34S enrichment reflects involvement of subducted volcanogenic massive sulfides deposits during Benioff-zone partial melting. Isotopic data on mineralized, accidental lithic fragments support the possible development of a porphyry-type system at El Chichón.

  4. SO2 photoexcitation mechanism links mass-independent sulfur isotopic fractionation in cryospheric sulfate to climate impacting volcanism.

    PubMed

    Hattori, Shohei; Schmidt, Johan A; Johnson, Matthew S; Danielache, Sebastian O; Yamada, Akinori; Ueno, Yuichiro; Yoshida, Naohiro

    2013-10-29

    Natural climate variation, such as that caused by volcanoes, is the basis for identifying anthropogenic climate change. However, knowledge of the history of volcanic activity is inadequate, particularly concerning the explosivity of specific events. Some material is deposited in ice cores, but the concentration of glacial sulfate does not distinguish between tropospheric and stratospheric eruptions. Stable sulfur isotope abundances contain additional information, and recent studies show a correlation between volcanic plumes that reach the stratosphere and mass-independent anomalies in sulfur isotopes in glacial sulfate. We describe a mechanism, photoexcitation of SO2, that links the two, yielding a useful metric of the explosivity of historic volcanic events. A plume model of S(IV) to S(VI) conversion was constructed including photochemistry, entrainment of background air, and sulfate deposition. Isotopologue-specific photoexcitation rates were calculated based on the UV absorption cross-sections of (32)SO2, (33)SO2, (34)SO2, and (36)SO2 from 250 to 320 nm. The model shows that UV photoexcitation is enhanced with altitude, whereas mass-dependent oxidation, such as SO2 + OH, is suppressed by in situ plume chemistry, allowing the production and preservation of a mass-independent sulfur isotope anomaly in the sulfate product. The model accounts for the amplitude, phases, and time development of Δ(33)S/δ(34)S and Δ(36)S/Δ(33)S found in glacial samples. We are able to identify the process controlling mass-independent sulfur isotope anomalies in the modern atmosphere. This mechanism is the basis of identifying the magnitude of historic volcanic events. PMID:23417298

  5. SO2 photoexcitation mechanism links mass-independent sulfur isotopic fractionation in cryospheric sulfate to climate impacting volcanism

    PubMed Central

    Hattori, Shohei; Schmidt, Johan A.; Johnson, Matthew S.; Danielache, Sebastian O.; Yamada, Akinori; Ueno, Yuichiro; Yoshida, Naohiro

    2013-01-01

    Natural climate variation, such as that caused by volcanoes, is the basis for identifying anthropogenic climate change. However, knowledge of the history of volcanic activity is inadequate, particularly concerning the explosivity of specific events. Some material is deposited in ice cores, but the concentration of glacial sulfate does not distinguish between tropospheric and stratospheric eruptions. Stable sulfur isotope abundances contain additional information, and recent studies show a correlation between volcanic plumes that reach the stratosphere and mass-independent anomalies in sulfur isotopes in glacial sulfate. We describe a mechanism, photoexcitation of SO2, that links the two, yielding a useful metric of the explosivity of historic volcanic events. A plume model of S(IV) to S(VI) conversion was constructed including photochemistry, entrainment of background air, and sulfate deposition. Isotopologue-specific photoexcitation rates were calculated based on the UV absorption cross-sections of 32SO2, 33SO2, 34SO2, and 36SO2 from 250 to 320 nm. The model shows that UV photoexcitation is enhanced with altitude, whereas mass-dependent oxidation, such as SO2 + OH, is suppressed by in situ plume chemistry, allowing the production and preservation of a mass-independent sulfur isotope anomaly in the sulfate product. The model accounts for the amplitude, phases, and time development of Δ33S/δ34S and Δ36S/Δ33S found in glacial samples. We are able to identify the process controlling mass-independent sulfur isotope anomalies in the modern atmosphere. This mechanism is the basis of identifying the magnitude of historic volcanic events. PMID:23417298

  6. What they eat is how they fractionate: controls on sulfur isotope fractionations during microbial sulfate reduction in culture and nature (Invited)

    NASA Astrophysics Data System (ADS)

    Bosak, T.; Sim, M.; Donovan, K.; Grabenstatter, J. D.; Ono, S.

    2010-12-01

    Some of the largest sulfur isotope effects are produced by microbial dissimilatory sulfate reduction. This biological signature is used to reconstruct the oxygenation of Earth’s surface, the coupled cycling of carbon and sulfur through geologic time and to constrain the evolution of sulfur-based metabolisms. However, mechanistic links between the isotopic signatures of sedimentary sulfides and sulfates and microbial physiologies and growth conditions are poorly understood. To address this, we investigate the fractionation of sulfur isotopes by marine sulfate reducing bacteria as a function of the type and the availability of the electron donors. DMSS-1, a bacterium that is unable to completely oxidize acetate to CO2, produces isotope effects between 5-46 ‰ during active growth on various electron donors in batch and continuous cultures. Overall, the largest isotope effects are produced at very slow dilution and growth rates, but appear to correlate best with the rate at which cells release free energy. Maximum sulfur isotope effects in continuous cultures are produced during very slow growth, when the physiology of the organism is visibly altered. Because the same genetic and enzymatic machinery can yield fractionations from ~ 5 to 46 ‰, we conclude that the upper range of sulfur isotope effects during microbial sulfate reduction depends primarily on the coupling between the intracellular processes coupling the oxidation of carbon to the reduction of sulfur. Future work will attempt to identify these processes and the underlying enzymatic machinery by identifying the changes in the expression of genes during microbial growth under conditions that yield low and high sulfur isotope effects.

  7. Impact-Related Sulfur Recycling in the Ancient Martian Crust; Evidence from S Multi-Isotope Systematics of Regolith Breccia NWA 7533

    NASA Astrophysics Data System (ADS)

    Lorand, J.-P.; Labidi, J.; Thomassot, E.; Rollion-Bard, C.; Belluci, J.; Whitehouse, M.; Nemchin, A.; Hewins, R. H.; Humayun, M.; Farquhar, J.; Zanda, B.; Remusat, L.; Pont, S.

    2016-08-01

    Sulfur isotopes indicate that NWA 7533 pyrite formed from recycling of photochemically processed sulfur onto the martian surface. Sulfate reduction into sulfides could have produced negative delta 34S coupled with a small non-zero value of delta 33S.

  8. Revised delta34S reference values for IAEA sulfur isotope reference materials S-2 and S-3.

    PubMed

    Mann, Jacqueline L; Vocke, Robert D; Kelly, W Robert

    2009-04-01

    Revised delta(34)S reference values with associated expanded uncertainties (95% confidence interval (C.I.)) are presented for the sulfur isotope reference materials IAEA-S-2 (22.62 +/- 0.16 per thousand) and IAEA-S-3 (-32.49 +/- 0.16 per thousand). These revised values are determined using two relative-difference measurement techniques, gas source isotope ratio mass spectrometry (GIRMS) and double-spike multi-collector thermal ionization mass spectrometry (MC-TIMS). Gas analyses have traditionally been considered the most robust for relative isotopic difference measurements of sulfur. The double-spike MC-TIMS technique provides an independent method for value-assignment validation and produces revised values that are both unbiased and more precise than previous value assignments. Unbiased delta(34)S values are required to anchor the positive and negative end members of the sulfur delta (delta) scale because they are the basis for reporting both delta(34)S values and the derived mass-independent Delta(33)S and Delta(36)S values.

  9. Sulfur Isotopes as Indicators of Amended Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation

    SciTech Connect

    Druhan, Jennifer L.; Conrad, Mark E.; Williams, Kenneth H.; N'Guessan, A. Lucie; Long, Philip E.; Hubbard, Susan S.

    2008-11-01

    Aqueous uranium (U(VI)) concentrations in a contaminated aquifer in Rifle Colorado have been successfully lowered through electron donor amended bioreduction. Samples collected during the acetate amendment experiment were analyzed for aqueous concentrations of Fe(II), sulfate, sulfide, acetate, U(VI), and δ34S of sulfate and sulfide to explore the utility of sulfur isotopes as indicators of in situ acetate amended sulfate and uranium bioreduction processes. Enrichment of up to 7‰ in δ34S of sulfate in down-gradient monitoring wells indicates a transition to elevated bacterial sulfate reduction. A depletion in Fe(II), sulfate, and sulfide concentrations at the height of sulfate reduction, along with an increase in the δ34S of sulfide to levels approaching the d34S values of sulfate, indicates sulfate limited conditions concurrent with a rebound in U(VI) concentrations. Upon cessation of acetate amendment, sulfate and sulfide concentrations increased, while δ34S values of sulfide returned to less than -20‰ and sulfate δ34S decreased to near-background values, indicating lower levels of sulfate reduction accompanied by a corresponding drop in U(VI). Results indicate a transition between electron donor and sulfate-limited conditions at the height of sulfate reduction and suggest stability of biogenic FeS precipitates following the end of acetate amendment.

  10. Sulfur isotope studies of the Stillwater Complex and associated rocks, Montana

    USGS Publications Warehouse

    Zientek, M.L.; Ripley, E.M.

    1990-01-01

    The stillwater Complex in south-central Montana is a late Archean layered, ultramafic to mafic intrusion emplaced into middle to late Archean metagraywacke, metashale, and iron-formation. Sulfide minerals are concentrated near the base of the intrusion in some chromitite layers, podiform pegmatoids, discontinuous discordant pods or pipes, and numerous thin, stratiform layers. This investigation focuses on the isotopic composition of sulfur in metamorphosed sedimentary rocks. Stillwater-associated sills and dikes, sulfide accumulations near the base of the complex, and platinum-group element-enriched sulfide mineralization that constitutes the J-M reef and the Picket Pin deposit. The ??34S values for 233 samples analyzed in this study have a mean of 0.4 per mil, a standard deviation of 1.7, and a maximum and minimum of -3.8 and 7.8 per mil, respectively. Despite the very narrow range of values, analysis of variance calculations confirms that the data comprise three statistically distinct groups. -from Authors

  11. Precise and accurate isotopic measurements using multiple-collector ICPMS

    NASA Astrophysics Data System (ADS)

    Albarède, F.; Telouk, Philippe; Blichert-Toft, Janne; Boyet, Maud; Agranier, Arnaud; Nelson, Bruce

    2004-06-01

    New techniques of isotopic measurements by a new generation of mass spectrometers equipped with an inductively-coupled-plasma source, a magnetic mass filter, and multiple collection (MC-ICPMS) are quickly developing. These techniques are valuable because of (1) the ability of ICP sources to ionize virtually every element in the periodic table, and (2) the large sample throughout. However, because of the complex trajectories of multiple ion beams produced in the plasma source whether from the same or different elements, the acquisition of precise and accurate isotopic data with this type of instrument still requires a good understanding of instrumental fractionation processes, both mass-dependent and mass-independent. Although physical processes responsible for the instrumental mass bias are still to be understood more fully, we here present a theoretical framework that allows for most of the analytical limitations to high precision and accuracy to be overcome. After a presentation of unifying phenomenological theory for mass-dependent fractionation in mass spectrometers, we show how this theory accounts for the techniques of standard bracketing and of isotopic normalization by a ratio of either the same or a different element, such as the use of Tl to correct mass bias on Pb. Accuracy is discussed with reference to the concept of cup efficiencies. Although these can be simply calibrated by analyzing standards, we derive a straightforward, very general method to calculate accurate isotopic ratios from dynamic measurements. In this study, we successfully applied the dynamic method to Nd and Pb as examples. We confirm that the assumption of identical mass bias for neighboring elements (notably Pb and Tl, and Yb and Lu) is both unnecessary and incorrect. We further discuss the dangers of straightforward standard-sample bracketing when chemical purification of the element to be analyzed is imperfect. Pooling runs to improve precision is acceptable provided the pooled

  12. Sulfur isotope study of chimney minerals and vent fluids from 21°N, East Pacific Rise: Hydrothermal sulfur sources and disequilibrium sulfate reduction

    NASA Astrophysics Data System (ADS)

    Woodruff, Laurel G.; Shanks, Wayne C., III

    1988-05-01

    Sulfur isotopic analyses of hydrothermal chimneys and coexisting fluids collected from hot vent areas at 21°N, East Pacific Rise, indicate δ34S values for sulfide minerals of 0.9-6.2‰ and for aqueous H2S of 1.3-5.5‰. The chemical processes resulting in mineral zoning of chimney structures are a controlling influence on 34S variation within individual chimneys. In general, coarsely crystalline chalcopyrite, which lines chimney interiors, is depleted in δ34S relative to exterior ZnS (either sphalerite or wurtzite). Chalcopyrite which formed by replacement of other sulfides has higher sulfur isotope values than chalcopyrite which precipitated directly from hydrothermal fluid. Bornite and other Cu-rich sulfides, which occur as thin layers replacing the outer margins of massive chalcopyrite zones, have the highest δ34S values of any 21°N samples, ranging from 5.2‰ to 6.2‰. The significant 34S enrichment in bornite requires reduction of isotopically heavy seawater-derived sulfate in the chimney walls. Vent fluid δ34SH2S values are similar to δ34S values of inner wall chimney sulfides for seven of 11 samples. In other samples, aqueous H2S is enriched isotopically in δ34S compared with coexisting sulfides, suggesting admixture of H2S derived from reduced seawater sulfate. The δ34S value of end-member hydrothermal fluid at 21°N is about 1.0-1.5‰, which is somewhat higher than basaltic sulfide, the main source of sulfur in the hydrothermal system. This 34S enrichment apparently is due to sulfate reduction in the deep hydrothermal system during conversion of basaltic pyrrhotite to pyrite. The South West (SW) vent field has significantly higher average δ34S values (3.1‰) compared with the other 21°N vent fields. The SW field is situated on the edge of a lava collapse structure, promoting development of an extensive feeder zone which is the site of near-surface sulfate reduction during redissolution of previously deposited anhydrite. The δ34S values for

  13. Isotopic evidence for the source of sulfur in the Upper Freeport coal bed (west-central Pennsylvania, U.S.A.)

    USGS Publications Warehouse

    Spiker, E. C.; Pierce, B.S.; Bates, A.L.; Stanton, R.W.

    1994-01-01

    Sulfur isotopic variations were used to determine the sources of sulfur in a medium-sulfur coal (???2 wt%S) that lacked marine influence, which is often cited as a major source of sulfur in coal. Variations in the amount and isotopic composition of the organic and pyritic sulfur among the coal-bed facies of the Upper Freeport coal bed (Middle Pennsylvanian) are attributed to differential incorporation of syngenetic and epigenetic sulfur. These variations reflect varying environmental conditions during paleopeat formation, porosity and permeability, and the availability of sulfate and iron. A large increase in the abundance and sulfur isotopic value of pyritic sulfur in the upper facies of the coal bed, in proximity to the overlying lacustrine shale, corresponds to an increase in massive and irregular forms of pyrite. This relationship is attributed to at least two stages of epigenetic pyrite incorporation. An early stage of epigenetic pyrite, moderately enriched in 34S, apparently formed during the fluvial-lacustrine period immediately following peat accumulation. A late stage of epigenetic pyrite, highly enriched in 34S, formed after compaction of the original peat as cleat- and fracture-filling pyrite; this sulfur was probably derived from bacterial reduction of dissolved sulfate in groundwater. Isotopic mass-balance calculations indicate that this late-stage epigenetic pyrite may account for up to ???50% of the pyritic sulfur in some upper facies of the coal bed. These results suggest that most of the pyritic sulfur in the Upper Freeport coal bed may be epigenetic, incorporated either soon after peat accumulation or later during coalification. ?? 1994.

  14. Transboundary transport of anthropogenic sulfur in PM2.5 at a coastal site in the Sea of Japan as studied by sulfur isotopic ratio measurement.

    PubMed

    Inomata, Yayoi; Ohizumi, Tsuyoshi; Take, Naoko; Sato, Keiichi; Nishikawa, Masataka

    2016-05-15

    Sulfur isotopic ratios (δ(34)S) in size separated aerosol particles (PM2.5 and coarse particles) were measured at Niigata-Maki facing the Sea of Japan. Non-sea salt δ(34)S (δ(34)Snss) in PM2.5 showed seasonal variations with relatively high values in winter (1.0-3.9‰ in spring, 2.8-4.5‰ in summer, 1.3-4.5‰ in autumn, 3.7-5.7‰ in winter). Taking into consideration air mass transport routes, δ(34)Snss in the air masses which originated in the Asian continent and were transported over the Sea of Japan to the monitoring sites were higher than those values for air masses which were transported over the Japanese islands after leaving the Asian continent for each season. Considering that the δ(34)Snss in sulfuric acid derived from domestic emissions in Japan are lower than those of δ(34)Snss in coal, the lower δ(34)Snss for the air mass transported over the Japanese islands suggest that sulfuric acid in PM2.5 modified the δ(34)Snss due to aerosol mixing with sulfuric acid in Japan. Material balance calculations suggested that the relative contribution of transboundary transport in winter was also higher than for other seasons (40-75% in spring, 51-63% in summer, 45-73% in autumn, and 53-81% in winter). In particular, the contribution to the air masses which were transported directly from the Asian continent was relatively large (75% in spring, 59% in autumn, 78% in winter) in comparison with that for the air masses which were transported over Japan.

  15. Sulfur Isotopic Compositions of Individual Aerosol Particles from Below and Within Stratocumulus Clouds over the Southeast Pacific Ocean During VOCALS

    NASA Astrophysics Data System (ADS)

    Bose, M.; Anderson, J. R.; Twohy, C. H.; Williams, P.

    2012-12-01

    The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) was a large multi-national field experiment that collected data and samples from a region of the southeast Pacific with the world's largest stratocumulus cloud systems. Samples examined here are residues of cloud droplets and ambient particles from below the clouds collected during flights of the NCAR C-130 off the coast of Chile. Selected samples were studied using scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS) in order to contribute to the understanding of the source of non-sea-salt sulfate in this region. Particles in the size range from 0.2 to 1μm diameter on holey and lacey carbon were characterized by SEM combined with energy dispersive spectrometry (EDS), thus identifying sulfur-containing particles. Subsequently, sulfur ion imaging of identified sea salt, ammonium sulfate and sodium sulfate particles was done with the Cameca Ametek NanoSIMS 50L at Arizona State University. A <1pA Cs+ beam was rastered over 5×5μm2 or 10×10μm2 areas while secondary ions (12C-, 16O-, 32S-, 34S-, 35Cl-) and secondary electrons were collected simultaneously at high mass resolution (m/Δm>10000). Each measurement typically consists of 5 to 8 frames (~5.4 min/frame). NIST barium sulfate and ammonium sulfate particles were used as isotopic standards. Preliminary analyses on a small pool of VOCALS individual particles show a wide range in sulfur isotopic compositions (δ34S = -56 to +41‰). In addition, the in-cloud particles are enriched in 32S, while the ambient particles exhibit 34S excesses. Isotopic data on a large inventory of particles is being currently acquired, which will be presented at the meeting. Data will be used to investigate sulfur sources (marine vs. continental) and the processing of aerosols through sulfate formation.

  16. Use of sulfur and nitrogen stable isotopes to determine the importance of whitebark pine nuts to Yellowstone grizzly bears

    USGS Publications Warehouse

    Felicetti, L.A.; Schwartz, C.C.; Rye, R.O.; Haroldson, M.A.; Gunther, K.A.; Phillips, D.L.; Robbins, C.T.

    2003-01-01

    Whitebark pine (Pinus albicaulis) is a masting species that produces relatively large, fat- and protein-rich nuts that are consumed by grizzly bears (Ursus arctos horribilis). Trees produce abundant nut crops in some years and poor crops in other years. Grizzly bear survival in the Greater Yellowstone Ecosystem is strongly linked to variation in pine-nut availability. Because whitebark pine trees are infected with blister rust (Cronartium ribicola), an exotic fungus that has killed the species throughout much of its range in the northern Rocky Mountains, we used stable isotopes to quantify the importance of this food resource to Yellowstone grizzly bears while healthy populations of the trees still exist. Whitebark pine nuts have a sulfur-isotope signature (9.2 ?? 1.3??? (mean ?? 1 SD)) that is distinctly different from those of all other grizzly bear foods (ranging from 1.9 ?? 1.7??? for all other plants to 3.1 ?? 2.6??? for ungulates). Feeding trials with captive grizzly bears were used to develop relationships between dietary sulfur-, carbon-, and nitrogen-isotope signatures and those of bear plasma. The sulfur and nitrogen relationships were used to estimate the importance of pine nuts to free-ranging grizzly bears from blood and hair samples collected between 1994 and 2001. During years of poor pine-nut availability, 72% of the bears made minimal use of pine nuts. During years of abundant cone availability, 8 ?? 10% of the bears made minimal use of pine nuts, while 67 ?? 19% derived over 51% of their assimilated sulfur and nitrogen (i.e., protein) from pine nuts. Pine nuts and meat are two critically important food resources for Yellowstone grizzly bears.

  17. Oxygen and sulfur isotope systematics of sulfate produced by bacterial and abiotic oxidation of pyrite

    USGS Publications Warehouse

    Balci, N.; Shanks, Wayne C.; Mayer, B.; Mandernack, K.W.

    2007-01-01

    To better understand reaction pathways of pyrite oxidation and biogeochemical controls on ??18O and ??34S values of the generated sulfate in acid mine drainage (AMD) and other natural environments, we conducted a series of pyrite oxidation experiments in the laboratory. Our biological and abiotic experiments were conducted under aerobic conditions by using O2 as an oxidizing agent and under anaerobic conditions by using dissolved Fe(III)aq as an oxidant with varying ??18OH2O values in the presence and absence of Acidithiobacillus ferrooxidans. In addition, aerobic biological experiments were designed as short- and long-term experiments where the final pH was controlled at ???2.7 and 2.2, respectively. Due to the slower kinetics of abiotic sulfide oxidation, the aerobic abiotic experiments were only conducted as long term with a final pH of ???2.7. The ??34SSO4 values from both the biological and abiotic anaerobic experiments indicated a small but significant sulfur isotope fractionation (???-0.7???) in contrast to no significant fractionation observed from any of the aerobic experiments. Relative percentages of the incorporation of water-derived oxygen and dissolved oxygen (O2) to sulfate were estimated, in addition to the oxygen isotope fractionation between sulfate and water, and dissolved oxygen. As expected, during the biological and abiotic anaerobic experiments all of the sulfate oxygen was derived from water. The percentage incorporation of water-derived oxygen into sulfate during the oxidation experiments by O2 varied with longer incubation and lower pH, but not due to the presence or absence of bacteria. These percentages were estimated as 85%, 92% and 87% from the short-term biological, long-term biological and abiotic control experiments, respectively. An oxygen isotope fractionation effect between sulfate and water (??18 OSO4 s(-) H2 O) of ???3.5??? was determined for the anaerobic (biological and abiotic) experiments. This measured ??18 OSO42 - s(-) H2

  18. Fire and Brimstone: The Microbially Mediated Formation of Elemental Sulfur Nodules from an Isotope and Major Element Study in the Paleo-Dead Sea

    PubMed Central

    Bishop, Tom; Turchyn, Alexandra V.; Sivan, Orit

    2013-01-01

    We present coupled sulfur and oxygen isotope data from sulfur nodules and surrounding gypsum, as well as iron and manganese concentration data, from the Lisan Formation near the Dead Sea (Israel). The sulfur isotope composition in the nodules ranges between -9 and -11‰, 27 to 29‰ lighter than the surrounding gypsum, while the oxygen isotope composition of the gypsum is constant around 24‰. The constant sulfur isotope composition of the nodule is consistent with formation in an ‘open system’. Iron concentrations in the gypsum increase toward the nodule, while manganese concentrations decrease, suggesting a redox boundary at the nodule-gypsum interface during aqueous phase diagenesis. We propose that sulfur nodules in the Lisan Formation are generated through bacterial sulfate reduction, which terminates at elemental sulfur. We speculate that the sulfate-saturated pore fluids, coupled with the low availability of an electron donor, terminates the trithionate pathway before the final two-electron reduction, producing thionites, which then disproportionate to form abundant elemental sulfur. PMID:24098403

  19. Carbon, nitrogen and sulfur isotopic characterization of biological samples from chemo-synthetic communities in southern Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Yamanaka, T.; Mizota, C.; Ishibashi, J.; Nakayama, N.; Tsunogai, U.; Morimoto, Y.; Kataoka, S.; Kosaka, A.; Maki, Y.; Fujiwara, Y.; Tsuchida, S.; Fujikura, K.

    2002-12-01

    Direct measurement of carbon, nitrogen, and sulfur isotopic compositions of the seafloor hydrothermal bacteria involves many difficulties, mainly due to lack of suitable size of samples. In contrast, the isotopic measurements of the hydrothermal vent animals can easily be made. The animals depends mainly on bacterial primary production. Carbon, nitrogen, and sulfur budget from the bacterial source should be estimated using the stable isotopic compositions of the soft tissue constituents. The hydrothermal environment involves several types of chemoautotrophc and methanotrophic bacteria such as suspending, matting, and endosymbiosis. Each hydrothermal vent animal feeds on or harbors the bacteria according to their physiology and ecology. For example, the crustaceans, Shinkaiya and Alvinocaris, feed on bacteria and the deep-sea mussel, Bathymodiolus, harbors endosymbionts in their gill tissues. Our objectives are to make clear the sources of carbon, nitrogen, and sulfur of these bacteria and the relationship between the bacteria and the geochemistry of emitting hydrothermal fluids. We studied the vent animals from two hydrothermal systems where the tectonic settings are significantly different. One is located on the volcanic front of the Ryukyu Arc and the other is located on the west edge of the Okinawa Trough back-arc basin. The former hydrothermal vent site is active in the caldera where sediment starved hydrothermal system, while the latter site is active on the thick sediment-covered small trough. The geological settings of these two hydrothermal sites would provide different geochemical environments. We will discuss how the vent animals succeed to the geochemical characteristics from the viewpoint of stable isotope geochemistry.

  20. Sulfur Isotope Chemistry of the Uzon Caldera Active Hydrothermal System, Kamchatka, Far-East Russia

    NASA Astrophysics Data System (ADS)

    Hollingsworth, E. R.; Crowe, D. E.

    2006-05-01

    The Uzon Caldera is an actively precipitating As-Sb-Au epithermal system located on the Kamchatka Peninsula of Far-East Russia. Present at the surface of the caldera is a remarkable diversity of thermal fluid types discharging within the geothermal fields. These fluids have subsequently produced a broad array of S- bearing alteration minerals both within and around pools, hotsprings, mudpots, and fumaroles. Using the δD/δ18O/δ34S and dissolved ion chemistry of the thermal fluids, three types were distinguished as follows: 1) an acid sulfate type with δD/δ18O/δ34S values ranging between -74.66‰ to -100.33‰, - 2.30‰ to -9.57‰, and -0.3‰ to 0.3‰ respectively with sulfate being the dominant anion ranging between 504ppm and 3439ppm 2) an alkali chloride type with δD/δ18O/δ34S values ranging between -97.22‰ to -104.37‰, - 8.8‰ to -11.43‰ respectively with chloride being the dominant anion ranging between 1090ppm to 2405ppm, and 3) a dilute type resulting from the mixture of the alkali-chloride endmember with the cold meteoric waters present at the surface subsequently generating δD/δ18O/δ34S values ranging between -82.00‰ to -119.34‰, -6.02‰ to -15.76‰, and +1.9‰ to +13.5‰ with dissolved ion concentrations falling along a mixing line between the two endmember components. The interpretations made from the presence of these three fluid types were used in conjunction with the δ34S of the S-bearing alteration minerals from within and around the various water and gas sources (values ranging between -1.94‰ to +5.7‰ and -5.19‰ to +1.6‰ respectively) to construct a sulfur evolution model for the Uzon's hydrothermal system. Results of the model show the chemical and isotopic processes responsible for the speciation and isotopic signature of the S-bearing phases collected at the surface (both aqueous and mineral) are not only dictated by the geologic processes at depth, but are also influenced by microbiological processes at the

  1. Climatic impact of the long-lasting 1783 Laki eruption: Inapplicability of mass-independent sulfur isotopic composition measurements

    NASA Astrophysics Data System (ADS)

    Schmidt, Anja; Thordarson, Thorvaldur; Oman, Luke D.; Robock, Alan; Self, Stephen

    2012-12-01

    The long-lasting 1783-1784 CE Laki flood lava eruption in Iceland released around 120 Tg of sulfur dioxide into the upper troposphere/lower stratosphere. Northern Hemisphere temperature proxy records of the 1780s indicate below-average temperatures for up to three years following the eruption. The very warm summer of 1783 in Europe, which was followed by a very cold winter, may have been caused by the eruption, but the mechanisms are not yet well understood. Some studies attributed the cold winter 1783-1784 to natural variability of climate. However, our climate model simulations show that the Laki radiative effects lasted long enough to contribute to the winter cooling. We suggest that sulfur isotopic composition measurements obtained using samples from Greenland ice cores do not provide evidence of either a short-lived volcanic aerosol cloud or a short-lived climatic impact of the Laki eruption. In fact, the applicability of mass-independent sulfur isotopic composition measurements for interpreting the climatic impact of any high-latitude eruption remains yet to be demonstrated.

  2. Early diagenetic processes of saline meromictic Lake Kai-ike, southwest Japan: III. Sulfur speciation and isotopes

    NASA Astrophysics Data System (ADS)

    Sakai, N.; Yamaguchi, K. E.; Oguri, K.

    2014-12-01

    ., 2010; Palaeo3). Geochemical characteristics of sulfur in the uppermost part of Lake Kai-ike sediment were significantly modified during early diagenesis. Such diagenetic modification for sulfur isotopes should be fully taken into account to better reconstruct past anoxic environment such as Cretaceous OAEs and Archean oceans.

  3. Sulfur isotope composition of metasomatised mantle xenoliths from the Bultfontein kimberlite (Kimberley, South Africa): Contribution from subducted sediments and the effect of sulfide alteration on S isotope systematics

    NASA Astrophysics Data System (ADS)

    Giuliani, Andrea; Fiorentini, Marco L.; Martin, Laure A. J.; Farquhar, James; Phillips, David; Griffin, William L.; LaFlamme, Crystal

    2016-07-01

    Sulfur isotopes are a powerful geochemical tracer in high-temperature processes, but have rarely been applied to the study of mantle metasomatism. In addition, there are very limited S isotope data on sub-continental lithospheric mantle (SCLM) material. For cratonic regions, these data are restricted to sulfide inclusions in diamonds. To provide new constraints on the S isotope composition of the SCLM and on the source(s) of mantle metasomatic fluids beneath the diamondiferous Kimberley region (South Africa), we investigated the S isotope systematics of five metasomatised mantle xenoliths from the Bultfontein kimberlite. Pentlandite and chalcopyrite in these xenoliths were analysed by in situ secondary-ion mass spectrometry (SIMS), with bulk-rock material measured by gas source isotope ratio mass spectrometry techniques. Based on previous studies, the xenoliths experienced different types of metasomatism to one another at distinct times (∼180 and ∼90-80 Ma). Contained pentlandite grains show variable alteration to heazlewoodite (i.e. Ni sulfide) + magnetite. The in situ S isotope analyses of pentlandite exhibit a relatively restricted range between -5.9 and - 1.4 ‰δ34 S (compared to VCDT), with no statistically meaningful differences between samples. Chalcopyrite only occurs in one sample and shows δ34 S values between -5.4 and - 1.0 ‰. The bulk-rock Ssulfide isotope analyses vary between -3.4 and + 0.8 ‰δ34 S. Importantly, the only sample hosting dominantly fresh sulfides shows a bulk-rock δ34 S value consistent with the mean value for the sulfides, whereas the other samples exhibit higher bulk 34S/32S ratios. The differences between bulk-rock and average in situδ34 S values are directly correlated with the degree of sulfide alteration. This evidence indicates that the elevated 34S/32S ratios in the bulk samples are not due to the introduction of heavy S (commonly as sulfates) and are best explained by isotopic fractionation coupled with the removal

  4. Tracing sources of crustal contamination using multiple S and Fe isotopes in the Hart komatiite-associated Ni-Cu-PGE sulfide deposit, Abitibi greenstone belt, Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Hiebert, R. S.; Bekker, A.; Houlé, M. G.; Wing, B. A.; Rouxel, O. J.

    2016-10-01

    Assimilation by mafic to ultramafic magmas of sulfur-bearing country rocks is considered an important contributing factor to reach sulfide saturation and form magmatic Ni-Cu-platinum group element (PGE) sulfide deposits. Sulfur-bearing sedimentary rocks in the Archean are generally characterized by mass-independent fractionation of sulfur isotopes that is a result of atmospheric photochemical reactions, which produces isotopically distinct pools of sulfur. Likewise, low-temperature processing of iron, through biological and abiotic redox cycling, produces a range of Fe isotope values in Archean sedimentary rocks that is distinct from the range of the mantle and magmatic Fe isotope values. Both of these signals can be used to identify potential country rock assimilants and their contribution to magmatic sulfide deposits. We use multiple S and Fe isotopes to characterize the composition of the potential iron and sulfur sources for the sulfide liquids that formed the Hart deposit in the Shaw Dome area within the Abitibi greenstone belt in Ontario (Canada). The Hart deposit is composed of two zones with komatiite-associated Ni-Cu-PGE mineralization; the main zone consists of a massive sulfide deposit at the base of the basal flow in the komatiite sequence, whereas the eastern extension consists of a semi-massive sulfide zone located 12 to 25 m above the base of the second flow in the komatiite sequence. Low δ56Fe values and non-zero δ34S and Δ33S values of the komatiitic rocks and associated mineralization at the Hart deposit is best explained by mixing and isotope exchange with crustal materials, such as exhalite and graphitic argillite, rather than intrinsic fractionation within the komatiite. This approach allows tracing the extent of crustal contamination away from the deposit and the degree of mixing between the sulfide and komatiite melts. The exhalite and graphitic argillite were the dominant contaminants for the main zone of mineralization and the eastern

  5. Tracing sources of crustal contamination using multiple S and Fe isotopes in the Hart komatiite-associated Ni-Cu-PGE sulfide deposit, Abitibi greenstone belt, Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Hiebert, R. S.; Bekker, A.; Houlé, M. G.; Wing, B. A.; Rouxel, O. J.

    2016-03-01

    Assimilation by mafic to ultramafic magmas of sulfur-bearing country rocks is considered an important contributing factor to reach sulfide saturation and form magmatic Ni-Cu-platinum group element (PGE) sulfide deposits. Sulfur-bearing sedimentary rocks in the Archean are generally characterized by mass-independent fractionation of sulfur isotopes that is a result of atmospheric photochemical reactions, which produces isotopically distinct pools of sulfur. Likewise, low-temperature processing of iron, through biological and abiotic redox cycling, produces a range of Fe isotope values in Archean sedimentary rocks that is distinct from the range of the mantle and magmatic Fe isotope values. Both of these signals can be used to identify potential country rock assimilants and their contribution to magmatic sulfide deposits. We use multiple S and Fe isotopes to characterize the composition of the potential iron and sulfur sources for the sulfide liquids that formed the Hart deposit in the Shaw Dome area within the Abitibi greenstone belt in Ontario (Canada). The Hart deposit is composed of two zones with komatiite-associated Ni-Cu-PGE mineralization; the main zone consists of a massive sulfide deposit at the base of the basal flow in the komatiite sequence, whereas the eastern extension consists of a semi-massive sulfide zone located 12 to 25 m above the base of the second flow in the komatiite sequence. Low δ56Fe values and non-zero δ34S and Δ33S values of the komatiitic rocks and associated mineralization at the Hart deposit is best explained by mixing and isotope exchange with crustal materials, such as exhalite and graphitic argillite, rather than intrinsic fractionation within the komatiite. This approach allows tracing the extent of crustal contamination away from the deposit and the degree of mixing between the sulfide and komatiite melts. The exhalite and graphitic argillite were the dominant contaminants for the main zone of mineralization and the eastern

  6. Sulfur concentration and isotopic variation in apatites from granitic to granodioritic plutons of a Cretaceous Cordilleran Batholith

    NASA Astrophysics Data System (ADS)

    Economos, R. C.

    2012-12-01

    Apatite is a common igneous accessory mineral with a high saturation temperature which can therefore crystallize over a significant portion of magmatic compositional space. Sulfur presents an opportunity to identify zoning in apatites. Unlike other trace elements, sulfur is relatively immobile in the apatite crystal structure and can be present in typical concentrations up to 1500 - 2000 ppm (or 0.5 to 1 wt% SO3). Sulfur concentration zoning in igneous apatites from ore producing magmatic systems has been identified (Streck and Dilles, 1998), but the interpretation of the cause of this zoning remains an open question. δ34S isotopic ratios of whole apatites have been used to track isotopic evolution associated with changes in magma fO2 and eruptive degassing (Rye, 2005). The presented work combines sulfur concentration mapping in zoned apatite crystals with in-situ SIMS 34S and 32S isotope measurements. Apatites were extracted from granite to granodiorite samples from the Cadiz Valley Batholith in the central Mojave Desert. This batholith is related to the pulse of Cretaceous Cordilleran magmatism that generated large batholiths in the Sierra Nevada and the Penninsular Ranges. The Mojave segment of the Cretaceous arc is unique in their construction into a full thickness of continental crust which exerted a strong influence on magmatic compositions. Apatite grains were mounted parallel to C axes, ground until grains were approximately bisected, and analyzed by Electron Microprobe at UCLA, for CaO, P2O5, SO3 and SiO2. Grains were surveyed and those yielding anomalous SO3 contents were investigated by micron-scale concentration mapping. Typical SO3 concentrations of apatites from all samples were ~0.2 wt%, while 8 to 10% of apatite grains from two samples contained cores with concentrations ranging up to 0.5 wt%. The sulfur zoning in these samples is oscillatory, in some grains representing 5 to 6 repetitions of high and low concentrations. Based on these textures

  7. Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry

    NASA Technical Reports Server (NTRS)

    Bandy, Alan R.; Thornton, Donald C.; Driedger, Arthur R., III

    1993-01-01

    A gas chromatograph/mass spectrometer is described for determining atmospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbonyl sulfide from aircraft and ship platforms. Isotopically labelled variants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integration time of 3 min was 1 pptv for sulfur dioxide and dimethyl sulfide and 0.2 pptv for carbon disulfide and carbonyl sulfide. All four species were simultaneously determined with a sample frequency of one sample per 6 min or greater. When only one or two species were determined, a frequency of one sample per 4 min was achieved. Because a calibration is included in each sample, no separate calibration sequence was needed. Instrument warmup was only a few minutes. The instrument was very robust in field deployments, requiring little maintenance.

  8. Formation and burial of pyrite and organic sulfur in mud sediments of the East China Sea inner shelf: Constraints from solid-phase sulfur speciation and stable sulfur isotope

    NASA Astrophysics Data System (ADS)

    Zhu, Mao-Xu; Shi, Xiao-Ning; Yang, Gui-Peng; Hao, Xiao-Chen

    2013-02-01

    Solid-phase sulfur speciation and stable sulfur isotopic compositions are used to elucidate the formation and burial of pyrite-sulfur (Spy) and organic sulfur (OS) at three selected sites in mud sediments of the East China Sea (ECS) inner shelf, and to infer potential factors influencing the preservation of Spy and OS in the sediments. Our results in combination with previous studies show that the overall reactivity of sedimentary organic matter (OM) is low, while OM at the site impacted by frequent algal-bloom events displays somewhat enhanced reactivity. We observed characteristically low contents of acid volatile sulfide (AVS) and Spy in the sediments, which can be attributed to low sulfate reduction rate due to high redox potential together with limited availability of labile OM. Several geochemical features, for example, persistent occurrence of S0, good coupling among the profiles of AVS, S0 and Spy, and large 34Spy depletion, all suggest that the polysulfide pathway and disproportionation are likely involved in the pyrite formation. Organic sulfur amounts in the sediments are at the lower end of OS contents reported in many other marine sediments around the world. The sources of OS are both biosynthetic and diagenetic, with the biosynthetic OS being the major share (59-73%). In one site studied (C702), enhanced accumulation of OS within the upper layers (14 cm) is believed to be associated with frequent algal-bloom events. Net burial fluxes of Spy and OS in the three sites studied range from 0.27 to 0.82 mmol/m2/d and from 0.22 to 0.74 mmol/m2/d, respectively. Sedimentation rate and algal-bloom events are two important factors influencing the spatial variability of Spy and OS burial fluxes in the whole shelf.

  9. Triple isotope composition of sulfur from nanomoles of dissolved sulfate on the MC-ICPMS Neptune (Invited)

    NASA Astrophysics Data System (ADS)

    Paris, G.; Sessions, A. L.; Subhas, A. V.; Adkins, J. F.

    2013-12-01

    Over the last decade, the increasing use of Inductively-Coupled plasma mass spectrometer (ICPMS) for measuring the isotopic composition of sulfur helped decreasing significantly the detection limit for analyzing dissolved sulfate, with no loss of precision. Because of intereferences on mass 33 and 36, only the two major isotopes were analyzed. Here, we present a new method to measure precise and accurate 34S /32S and 33S /32S ratios from sulfate in solution. Understanding past and modern sulfur cycle is crucial on many points of view and exploring the isotopic composition of sulfur from Carbonate Associated Sulfate (CAS) during geological times or sulfate from seawater or porewaters provide essential information. For carbonates, existing methods focus on samples rather rich in CAS (>100 ppm) or samples available in important amounts (> 1g). Samples with either very low sulfate concentration (Archean carbonates or continental waters, for instance) and/or samples with limited available amounts (such as foraminifera) require a new analytical method. Isotopic composition of many trace components are successfully measured on MC-ICPMS (MultiCollector ICPMS). The ThermoScientific magnetic sector ICPMS Neptune has already been used successfully for bulk and in-situ δ34S evaluation of sulfate and sulfide minerals [1] and organic compounds [2]. Isotopic composition measurement on the Neptune requires however removal of the complex matrix of the samples so that samples are analyzed as sodium sulfate diluted in 5% HNO3. Sulfate is purified using the AG1X8 anionic resin to remove cations. Because sulfate is not volatile at low temperatures, we use a desolvating membrane (Aridus, Cetac) in order to decrease the various oxygen and S-H interferences on the sulfur peaks. Working at High Resolution (M/ΔM=10000), 32S-H interferences can be resolved and the 33S signal can be measured on an interference-free narrow shoulder. This method allows 34S /32S and 33S /32S ratios measurement

  10. In situ sulfur isotopes (δ(34)S and δ(33)S) analyses in sulfides and elemental sulfur using high sensitivity cones combined with the addition of nitrogen by laser ablation MC-ICP-MS.

    PubMed

    Fu, Jiali; Hu, Zhaochu; Zhang, Wen; Yang, Lu; Liu, Yongsheng; Li, Ming; Zong, Keqing; Gao, Shan; Hu, Shenghong

    2016-03-10

    The sulfur isotope is an important geochemical tracer in diverse fields of geosciences. In this study, the effects of three different cone combinations with the addition of N2 on the performance of in situ S isotope analyses were investigated in detail. The signal intensities of S isotopes were improved by a factor of 2.3 and 3.6 using the X skimmer cone combined with the standard sample cone or the Jet sample cone, respectively, compared with the standard arrangement (H skimmer cone combined with the standard sample cone). This signal enhancement is important for the improvement of the precision and accuracy of in situ S isotope analysis at high spatial resolution. Different cone combinations have a significant effect on the mass bias and mass bias stability for S isotopes. Poor precisions of S isotope ratios were obtained using the Jet and X cones combination at their corresponding optimum makeup gas flow when using Ar plasma only. The addition of 4-8 ml min(-1) nitrogen to the central gas flow in laser ablation MC-ICP-MS was found to significantly enlarge the mass bias stability zone at their corresponding optimum makeup gas flow in these three different cone combinations. The polyatomic interferences of OO, SH, OOH were also significantly reduced, and the interference free plateaus of sulfur isotopes became broader and flatter in the nitrogen mode (N2 = 4 ml min(-1)). However, the signal intensity of S was not increased by the addition of nitrogen in this study. The laser fluence and ablation mode had significant effects on sulfur isotope fractionation during the analysis of sulfides and elemental sulfur by laser ablation MC-ICP-MS. The matrix effect among different sulfides and elemental sulfur was observed, but could be significantly reduced by line scan ablation in preference to single spot ablation under the optimized fluence. It is recommended that the d90 values of the particles in pressed powder pellets for accurate and precise S isotope analysis

  11. In situ sulfur isotopes (δ(34)S and δ(33)S) analyses in sulfides and elemental sulfur using high sensitivity cones combined with the addition of nitrogen by laser ablation MC-ICP-MS.

    PubMed

    Fu, Jiali; Hu, Zhaochu; Zhang, Wen; Yang, Lu; Liu, Yongsheng; Li, Ming; Zong, Keqing; Gao, Shan; Hu, Shenghong

    2016-03-10

    The sulfur isotope is an important geochemical tracer in diverse fields of geosciences. In this study, the effects of three different cone combinations with the addition of N2 on the performance of in situ S isotope analyses were investigated in detail. The signal intensities of S isotopes were improved by a factor of 2.3 and 3.6 using the X skimmer cone combined with the standard sample cone or the Jet sample cone, respectively, compared with the standard arrangement (H skimmer cone combined with the standard sample cone). This signal enhancement is important for the improvement of the precision and accuracy of in situ S isotope analysis at high spatial resolution. Different cone combinations have a significant effect on the mass bias and mass bias stability for S isotopes. Poor precisions of S isotope ratios were obtained using the Jet and X cones combination at their corresponding optimum makeup gas flow when using Ar plasma only. The addition of 4-8 ml min(-1) nitrogen to the central gas flow in laser ablation MC-ICP-MS was found to significantly enlarge the mass bias stability zone at their corresponding optimum makeup gas flow in these three different cone combinations. The polyatomic interferences of OO, SH, OOH were also significantly reduced, and the interference free plateaus of sulfur isotopes became broader and flatter in the nitrogen mode (N2 = 4 ml min(-1)). However, the signal intensity of S was not increased by the addition of nitrogen in this study. The laser fluence and ablation mode had significant effects on sulfur isotope fractionation during the analysis of sulfides and elemental sulfur by laser ablation MC-ICP-MS. The matrix effect among different sulfides and elemental sulfur was observed, but could be significantly reduced by line scan ablation in preference to single spot ablation under the optimized fluence. It is recommended that the d90 values of the particles in pressed powder pellets for accurate and precise S isotope analysis

  12. Carbon and sulfur isotopic signatures of ancient life and environment at the microbial scale: Neoarchean shales and carbonates.

    PubMed

    Williford, K H; Ushikubo, T; Lepot, K; Kitajima, K; Hallmann, C; Spicuzza, M J; Kozdon, R; Eigenbrode, J L; Summons, R E; Valley, J W

    2016-03-01

    An approach to coordinated, spatially resolved, in situ carbon isotope analysis of organic matter and carbonate minerals, and sulfur three- and four-isotope analysis of pyrite with an unprecedented combination of spatial resolution, precision, and accuracy is described. Organic matter and pyrite from eleven rock samples of Neoarchean drill core express nearly the entire range of δ(13) C, δ(34) S, Δ(33) S, and Δ(36) S known from the geologic record, commonly in correlation with morphology, mineralogy, and elemental composition. A new analytical approach (including a set of organic calibration standards) to account for a strong correlation between H/C and instrumental bias in SIMS δ(13) C measurement of organic matter is identified. Small (2-3 μm) organic domains in carbonate matrices are analyzed with sub-permil accuracy and precision. Separate 20- to 50-μm domains of kerogen in a single ~0.5 cm(3) sample of the ~2.7 Ga Tumbiana Formation have δ(13) C = -52.3 ± 0.1‰ and -34.4 ± 0.1‰, likely preserving distinct signatures of methanotrophy and photoautotrophy. Pyrobitumen in the ~2.6 Ga Jeerinah Formation and the ~2.5 Ga Mount McRae Shale is systematically (13) C-enriched relative to co-occurring kerogen, and associations with uraniferous mineral grains suggest radiolytic alteration. A large range in sulfur isotopic compositions (including higher Δ(33) S and more extreme spatial gradients in Δ(33) S and Δ(36) S than any previously reported) are observed in correlation with morphology and associated mineralogy. Changing systematics of δ(34) S, Δ(33) S, and Δ(36) S, previously investigated at the millimeter to centimeter scale using bulk analysis, are shown to occur at the micrometer scale of individual pyrite grains. These results support the emerging view that the dampened signature of mass-independent sulfur isotope fractionation (S-MIF) associated with the Mesoarchean continued into the early Neoarchean, and that the connections

  13. Sulfur isotope analysis of cinnabar from Roman wall paintings by elemental analysis/isotope ratio mass spectrometry--tracking the origin of archaeological red pigments and their authenticity.

    PubMed

    Spangenberg, Jorge E; Lavric, Jost V; Meisser, Nicolas; Serneels, Vincent

    2010-10-15

    The most valuable pigment of the Roman wall paintings was the red color obtained from powdered cinnabar (Minium Cinnabaris pigment), the red mercury sulfide (HgS), which was brought from mercury (Hg) deposits in the Roman Empire. To address the question of whether sulfur isotope signatures can serve as a rapid method to establish the provenance of the red pigment in Roman frescoes, we have measured the sulfur isotope composition (δ(34)S value in ‰ VCDT) in samples of wall painting from the Roman city Aventicum (Avenches, Vaud, Switzerland) and compared them with values from cinnabar from European mercury deposits (Almadén in Spain, Idria in Slovenia, Monte Amiata in Italy, Moschellandsberg in Germany, and Genepy in France). Our study shows that the δ(34)S values of cinnabar from the studied Roman wall paintings fall within or near to the composition of Almadén cinnabar; thus, the provenance of the raw material may be deduced. This approach may provide information on provenance and authenticity in archaeological, restoration and forensic studies of Roman and Greek frescoes.

  14. Sulfur, carbon, and oxygen isotope variations in submarine hydrothermal deposits of Guaymas Basin, Gulf of California, USA

    USGS Publications Warehouse

    Peter, J.M.; Shanks, Wayne C.

    1992-01-01

    Sulfur, carbon, and oxygen isotope values were measured in sulfide, sulfate, and carbonate from hydrothermal chimney, spire, and mound samples in the southern trough of Guaymas Basin, Gulf of California, USA. ??34S values of sulfides range from -3.7 to 4.5%. and indicate that sulfur originated from several sources: 1. (1) dissolution of 0??? sulfide contained within basaltic rocks, 2. (2) thermal reduction of seawater sulfate during sediment alteration reactions in feeder zones to give sulfide with positive ??34S, and 3. (3) entrainment or leaching of isotopically light (negative-??34S) bacteriogenic sulfide from sediments underlying the deposits. ??34S of barite and anhydrite indicate sulfur derivation mainly from unfractionated seawater sulfate, although some samples show evidence of sulfate reduction and sulfide oxidation reactions during mixing within chimneys. Oxygen isotope temperatures calculated for chimney calcites are in reasonable agreement with measured vent fluid temperatures and fluid inclusion trapping temperatures. Hydrothermal fluids that formed calcite-rich chimneys in the southern trough of Guaymas Basin were enriched in 18O with respect to seawater by about 2.4??? due to isotopic exchange with sedimentary and/or basaltic rocks. Carbon isotope values of calcite range from -9.6 to -14.0??? ??34CpDB, indicating that carbon was derived in approximately equal quantities from the dissolution of marine carbonate minerals and the oxidation of organic matter during migration of hydrothermal fluid through the underlying sediment column. Statistically significant positive, linear correlations of ??34S, ??34C, and ??18O of sulfides and calcites with geographic location within the southern trough of Guaymas Basin are best explained by variations in water/rock ( w r) ratios or sediment reactivity within subsurface alteration zones. Low w r ratios and the leaching of detrital carbonates and bacteriogenic sulfides at the southern vent sites result in relatively

  15. Sulfur isotope fractionation as an early indicator of microbial sulfate reduction under conditions of stimulated subsurface metal bioremediation

    NASA Astrophysics Data System (ADS)

    Druhan, J. L.; Conrad, M. E.; Williams, K. H.; Steefel, C.; Depaolo, D. J.

    2010-12-01

    Sustained in situ metal remediation presents a challenge in quantifying the onset, extent and overlap of each major chemical transition, as well as the evolution of physical, chemical and microbial parameters over multiple amendments. These parameters define a biogeochemically dynamic system requiring numerical reactive transport modeling to accurately predict cumulative contaminant stabilization. The use of novel monitoring tools to improve input parameters for numerical models is an essential component of the remediation strategy. Here we present aqueous geochemical data from three consecutive years of amended uranium bioremediation in a single well gallery from the US Department of Energy’s Environmental Remediation Science Program field site in Rifle, Colorado. Uranium bioremediation at the Rifle site is achieved through introduction of acetate at mM concentrations to stimulate first ferric iron reducers and subsequently sulfate reducers both naturally occurring in the aquifer. The factors controlling the onset of sulfate reduction and the extent to which iron and sulfate reduction can proceed concurrently are not well understood, and the initiation of sulfate reducing bacteria (SRB) activity must be closely monitored through aqueous geochemical data. Average background sulfate concentration in the aquifer is 9.6 mM with a 2σ standard deviation of 2.3, meaning that a 25% decrease in sulfate is necessary in order to identify sulfate reduction beyond background variation. Detection of aqueous sulfide should provide a more sensitive indicator of sulfate reduction, but the presence of ferrous iron in solution precipitates sulfides from the aqueous phase, causing a decline in measured sulfide concentrations and a lag in the onset of measurable sulfides up to 18 days after sulfate concentrations decrease. Sulfur isotopes present a means of overcoming this limitation. SRB fractionation factors are >10‰ even in open systems, meaning a 10% decrease in sulfate

  16. Methane-derived carbonates in a native sulfur deposit: stable isotope and trace element discriminations related to the transformation of aragonite to calcite.

    PubMed

    Böttcher, M E; Parafiniuk, J

    1997-07-01

    Abstract Stable isotope ((13)C, (18)O, (34)S) and trace element (Sr(2+), Mg(2+), Mn(2+), Ba(2+), Na(+)) investigations of elemental sulfur, primary calcites and mixtures of aragonite with secondary, post-aragonitic calcite from sulfur-bearing limestones have provided new insights into the geochemistry of the mineral forming environment of the native sulfur deposit at Machów (SE-Poland). The carbon isotopic composition of carbonates (δ(13)C = -41 to -47‰ vs. PDB) associated with native sulfur (δ(34)S = + 10 to + 15‰ vs. V-CDT) relates their formation to the microbiological anaerobic oxidation of methane and the reduction of sulfate derived from Miocene gypsum. From a comparison with experimentally derived fractionation factors the element ratios of the aqueous fluids responsible for carbonate formation are estimated. In agreement with field and laboratory observations, ratios near seawater composition are obtained for primary aragonite, whereas the fluids were relatively enriched in dissolved calcium during the formation of primary and secondary calcites. Based on the oxygen isotope composition of the carbonates (δ(18)O = -3.9 to -5.9‰ vs. PDB) and a secondary SrSO(4) (δ(18)O = + 20‰ vs. SMOW; δ(34)S = + 59‰ vs. V-CDT), maximum formation temperatures of 35°C (carbonates) and 47°C (celestite) are obtained, in agreement with estimates for West Ukraine sulfur ores. The sulfur isotopic composition of elemental sulfur associated with carbonates points to intense microbial reduction of sulfate derived from Miocene gypsum (δ(34)S ≈ + 23‰) prior to the re-oxidation of dissolved reduced sulfur species.

  17. Cretaceous shales from the western interior of North America: sulfur/carbon ratios and sulfur-isotope composition.

    USGS Publications Warehouse

    Gautier, D.L.

    1986-01-01

    Sulphur/carbon ratios in cores of selected Cretaceous marine shales average 0.67, a value greater than that observed in recent marine sediments and much higher than global values calculated for the Cretaceous. This may be ascribed to generally low levels of bioturbation and enhanced efficiency of sulphate reduction due to low oxygen levels in Cretaceous seaways. Isotopic compositions of pyrite sulphur vary systematically with level of oxygenation of the depositional environment and therefore with organic carbon abundance and type of organic matter. Samples with >4% organic carbon are extremely depleted in 34S (mean delta 34S -31per mille) and contain hydrogen-rich organic matter. Samples containing <1.5% organic carbon display relatively 'heavy' but wide-ranging delta 34S values (-34.6 to +16.8per mille) and contain hydrogen-poor organic matter. Samples with intermediate amounts of organic carbon have average delta 34S of -25.9per mille and contain both types of organic matter. Relations between the nature of these shales, and their sedimentation rate and depositional environment are discussed.-L.C.H.

  18. From the Cover: Sulfur isotopes of organic matter preserved in 3.45-billion-year-old stromatolites reveal microbial metabolism

    NASA Astrophysics Data System (ADS)

    Bontognali, Tomaso R. R.; Sessions, Alex L.; Allwood, Abigail C.; Fischer, Woodward W.; Grotzinger, John P.; Summons, Roger E.; Eiler, John M.

    2012-09-01

    The 3.45-billion-year-old Strelley Pool Formation of Western Australia preserves stromatolites that are considered among the oldest evidence for life on Earth. In places of exceptional preservation, these stromatolites contain laminae rich in organic carbon, interpreted as the fossil remains of ancient microbial mats. To better understand the biogeochemistry of these rocks, we performed microscale in situ sulfur isotope measurements of the preserved organic sulfur, including both Δ33S and . This approach allows us to tie physiological inference from isotope ratios directly to fossil biomass, providing a means to understand sulfur metabolism that is complimentary to, and independent from, inorganic proxies (e.g., pyrite). Δ33S values of the kerogen reveal mass-anomalous fractionations expected of the Archean sulfur cycle, whereas values show large fractionations at very small spatial scales, including values below -15‰. We interpret these isotopic patterns as recording the process of sulfurization of organic matter by H2S in heterogeneous mat pore-waters influenced by respiratory S metabolism. Positive Δ33S anomalies suggest that disproportionation of elemental sulfur would have been a prominent microbial process in these communities.

  19. Spatial and Temporal Trends in the Carbon, Nitrogen, and Sulfur Isotopes of Stream DOM From 10 Watersheds at the HJ Andrews Experimental Forest.

    NASA Astrophysics Data System (ADS)

    Frentress, J.; Kendall, C.; Lajtha, K.; Jones, J.

    2008-12-01

    In order to better understand sources of dissolved organic matter (DOM) in streams from the small to large watershed scales, we initiated a one-year investigation of the chemical and isotopic characteristics of DOM at the HJ Andrews Experimental Forest (HJA) in Blue River, OR. DOM is a biologically significant loss from these watersheds, but its sources (forest floor, mineral soil, riparian zones, stream biota) are debated. Traditional chemical characterizations of DOM like SUVA and FI have been useful in conceptualizing and modeling streamflow sources, however, an improved method for assessing DOM quality is needed to adequately differentiate DOM from sources within the watershed. The isotopic characterization of inorganic molecules like nitrate has provided insight to the role of subsurface and surface processes governing the production and transport of critical nutrients, and yet to date, little work has been done to examine the usefulness of isotopic characterization of organically bound nutrients. We apply the isotopic characterization approach to DOM in order to better understand DOM production, transformation, and transport to streams in a range of watershed sizes. Major questions addressed in this research are: 1) Where in the watershed does stream DOM come from? 2) How do DOM sources vary temporally? 3) How do physical attributes of the watershed mediate DOM quality? A relatively new solid-phase extraction technique using C-18 resin was used to isolate DOM in water samples from 10 watersheds, ranging in size from 10 to 6200 hectares, on 3-week intervals from May 2007 to June 2008. The modified technique allowed for small (1 Liter) sample sizes and short processing times to reduce the costs of analysis. The capacity of carbon, nitrogen and sulfur isotopic characterizations of DOM, as well as traditional methods like SUVA and C:N, to predict physical watershed attributes (i.e. mean residence time, soil depth, elevation, gradient) and land use history (timber

  20. Determination of total sulfur at microgram per gram levels in geological materials by oxidation of sulfur into sulfate with in situ generation of bromine using isotope dilution high-resolution ICPMS.

    PubMed

    Makishima, A; Nakamura, E

    2001-06-01

    We have developed a new, simple, and accurate method for the determination of total sulfur at microgram per gram levels in milligram-sized silicate materials with isotope dilution high-resolution inductively coupled plasma mass spectrometry equipped with a flow injection system. In this method, sulfur can be quantitatively oxidized by bromine into sulfate with achievement of isotope equilibrium between the sample and spike. Detection limits for 32S+ and 34S+ in the ideal solution and silicate samples were 1 and 6 ng mL(-1) and 0.07 and 0.3 microg g(-1), respectively. The total blank was 46 ng, so that a 40-mg silicate sample containing 10 mirog g(-1) sulfur can be measured with a blank correction of < 10%. This total blank can be lowered to 8 ng if a low-blank air system is used for evaporations. To evaluate the applicability of this method, we analyzed not only silicate reference materials with sulfur content of 5.25-489 microg g(-1) and sample sizes of 13-40 mg but also the Allende meteorite with a sulfur content of 2%. The reproducibility for various rock types was < 9%, even though blank corrections in some samples of low sulfur content were up to 24%. This method is suitable for analyzing geological samples as well environmental samples such as soils, sediments, and water samples.

  1. Sulfur isotope fractionation by broadband UV radiation to optically thin SO2 under reducing atmosphere

    NASA Astrophysics Data System (ADS)

    Endo, Yoshiaki; Ueno, Yuichiro; Aoyama, Shinnosuke; Danielache, Sebastian O.

    2016-11-01

    Photochemical mechanisms of Sulfur Mass-Independent Fractionation (S-MIF) are still poorly understood. Previous laboratory experiments have indicated that the S-MIF depends largely on the spectrum of the incident light source and the partial pressure of SO2, though the basic character of the Archean S-MIF (Δ36S / Δ33S = ∼ - 1) has never been reproduced. We have conducted new photochemical experiments at low pSO2 (1-10 Pa) conditions under the presence of CO and found a reasonable mechanism to reproduce the Δ36S/Δ33S slope about -1. As previously suggested (Ono et al., 2013), the low pSO2 is key to studying the self-shielding effect within a range of realistic atmospheric conditions. Also, reducing conditions are critical for simulating the O2-poor atmosphere, whereas photolysis of pure SO2 provides excess O atoms that significantly change the overall chemistry. Our experimental results confirmed that significant S-MIF (Δ36S / Δ33S = - 2.4) can be produced by self-shielding in the SO2 photolysis band (185-220 nm), even if the SO2 column density is as low as 1016 molecules cm-2. Thus, photolysis within a volcanic plume of ∼0.1 ppm SO2 is capable of producing a large S-MIF signature. The isotopic fractionations originating from the different absorption cross sections of SO2 isotopologues (i.e. wavelength dependent effect; without self-shielding) are only minor (potentially up to +4‰ for Δ33S). Under reducing conditions, however, another S-MIF signal with Δ36S/Δ33S ratio of ∼+0.7 is produced due to collision-induced intersystem crossing (ISC) from singlet to triplet states of SO2 (Whitehill et al., 2013), and should also be transferred into the final product that is responsible for changing the Δ36S/Δ33S slope. Based on a photochemical model of the S-O-C system with the two S-MIF-yielding reactions, the largest S-MIF observed in the late Archean Mt. McRae Fm. (Δ33S = + 9.4 ‰, Δ36S = - 7.5 ‰) can be reproduced by solar UV irradiation of a SO2

  2. In situ sulfur isotope analysis of sulfide minerals by SIMS: Precision and accuracy, with application to thermometry of ~3.5Ga Pilbara cherts

    USGS Publications Warehouse

    Kozdon, R.; Kita, N.T.; Huberty, J.M.; Fournelle, J.H.; Johnson, C.A.; Valley, J.W.

    2010-01-01

    Secondary ion mass spectrometry (SIMS) measurement of sulfur isotope ratios is a potentially powerful technique for in situ studies in many areas of Earth and planetary science. Tests were performed to evaluate the accuracy and precision of sulfur isotope analysis by SIMS in a set of seven well-characterized, isotopically homogeneous natural sulfide standards. The spot-to-spot and grain-to-grain precision for δ34S is ± 0.3‰ for chalcopyrite and pyrrhotite, and ± 0.2‰ for pyrite (2SD) using a 1.6 nA primary beam that was focused to 10 µm diameter with a Gaussian-beam density distribution. Likewise, multiple δ34S measurements within single grains of sphalerite are within ± 0.3‰. However, between individual sphalerite grains, δ34S varies by up to 3.4‰ and the grain-to-grain precision is poor (± 1.7‰, n = 20). Measured values of δ34S correspond with analysis pit microstructures, ranging from smooth surfaces for grains with high δ34S values, to pronounced ripples and terraces in analysis pits from grains featuring low δ34S values. Electron backscatter diffraction (EBSD) shows that individual sphalerite grains are single crystals, whereas crystal orientation varies from grain-to-grain. The 3.4‰ variation in measured δ34S between individual grains of sphalerite is attributed to changes in instrumental bias caused by different crystal orientations with respect to the incident primary Cs+ beam. High δ34S values in sphalerite correlate to when the Cs+ beam is parallel to the set of directions , from [111] to [110], which are preferred directions for channeling and focusing in diamond-centered cubic crystals. Crystal orientation effects on instrumental bias were further detected in galena. However, as a result of the perfect cleavage along {100} crushed chips of galena are typically cube-shaped and likely to be preferentially oriented, thus crystal orientation effects on instrumental bias may be obscured. Test were made to improve the analytical

  3. Iron-Isotopic Fractionation Studies Using Multiple Collector Inductively Coupled Plasma Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Anbar, A. D.; Zhang, C.; Barling, J.; Roe, J. E.; Nealson, K. H.

    1999-01-01

    The importance of Fe biogeochemistry has stimulated interest in Fe isotope fractionation. Recent studies using thermal ionization mass spectrometry (TIMS) and a "double spike" demonstrate the existence of biogenic Fe isotope effects. Here, we assess the utility of multiple-collector inductively-coupled plasma mass spectrometry(MC-ICP-MS) with a desolvating sample introduction system for Fe isotope studies, and present data on Fe biominerals produced by a thermophilic bacterium. Additional information is contained in the original extended abstract.

  4. Barite in hydrothermal environments as a recorder of subseafloor processes: a multiple-isotope study from the Loki's Castle vent field.

    PubMed

    Eickmann, B; Thorseth, I H; Peters, M; Strauss, H; Bröcker, M; Pedersen, R B

    2014-07-01

    Barite chimneys are known to form in hydrothermal systems where barium-enriched fluids generated by leaching of the oceanic basement are discharged and react with seawater sulfate. They also form at cold seeps along continental margins, where marine (or pelagic) barite in the sediments is remobilized because of subseafloor microbial sulfate reduction. We test the possibility of using multiple sulfur isotopes (δ34S, Δ33S, ∆36S) of barite to identify microbial sulfate reduction in a hydrothermal system. In addition to multiple sulfur isotopes, we present oxygen (δ18O) and strontium (87Sr/86Sr) isotopes for one of numerous barite chimneys in a low-temperature (~20 °C) venting area of the Loki's Castle black smoker field at the ultraslow-spreading Arctic Mid-Ocean Ridge (AMOR). The chemistry of the venting fluids in the barite field identifies a contribution of at least 10% of high-temperature black smoker fluid, which is corroborated by 87Sr/86 Sr ratios in the barite chimney that are less radiogenic than in seawater. In contrast, oxygen and multiple sulfur isotopes indicate that the fluid from which the barite precipitated contained residual sulfate that was affected by microbial sulfate reduction. A sulfate reduction zone at this site is further supported by the multiple sulfur isotopic composition of framboidal pyrite in the flow channel of the barite chimney and in the hydrothermal sediments in the barite field, as well as by low SO4 and elevated H2S concentrations in the venting fluids compared with conservative mixing values. We suggest that the mixing of ascending H2- and CH4-rich high-temperature fluids with percolating seawater fuels microbial sulfate reduction, which is subsequently recorded by barite formed at the seafloor in areas where the flow rate is sufficient. Thus, low-temperature precipitates in hydrothermal systems are promising sites to explore the interactions between the geosphere and biosphere in order to evaluate the microbial impact on

  5. Barite in hydrothermal environments as a recorder of subseafloor processes: a multiple-isotope study from the Loki's Castle vent field.

    PubMed

    Eickmann, B; Thorseth, I H; Peters, M; Strauss, H; Bröcker, M; Pedersen, R B

    2014-07-01

    Barite chimneys are known to form in hydrothermal systems where barium-enriched fluids generated by leaching of the oceanic basement are discharged and react with seawater sulfate. They also form at cold seeps along continental margins, where marine (or pelagic) barite in the sediments is remobilized because of subseafloor microbial sulfate reduction. We test the possibility of using multiple sulfur isotopes (δ34S, Δ33S, ∆36S) of barite to identify microbial sulfate reduction in a hydrothermal system. In addition to multiple sulfur isotopes, we present oxygen (δ18O) and strontium (87Sr/86Sr) isotopes for one of numerous barite chimneys in a low-temperature (~20 °C) venting area of the Loki's Castle black smoker field at the ultraslow-spreading Arctic Mid-Ocean Ridge (AMOR). The chemistry of the venting fluids in the barite field identifies a contribution of at least 10% of high-temperature black smoker fluid, which is corroborated by 87Sr/86 Sr ratios in the barite chimney that are less radiogenic than in seawater. In contrast, oxygen and multiple sulfur isotopes indicate that the fluid from which the barite precipitated contained residual sulfate that was affected by microbial sulfate reduction. A sulfate reduction zone at this site is further supported by the multiple sulfur isotopic composition of framboidal pyrite in the flow channel of the barite chimney and in the hydrothermal sediments in the barite field, as well as by low SO4 and elevated H2S concentrations in the venting fluids compared with conservative mixing values. We suggest that the mixing of ascending H2- and CH4-rich high-temperature fluids with percolating seawater fuels microbial sulfate reduction, which is subsequently recorded by barite formed at the seafloor in areas where the flow rate is sufficient. Thus, low-temperature precipitates in hydrothermal systems are promising sites to explore the interactions between the geosphere and biosphere in order to evaluate the microbial impact on

  6. Stable isotope compositions of serpentinite seamounts in the Mariana forearc: Serpentinization processes, fluid sources and sulfur metasomatism

    USGS Publications Warehouse

    Alt, J.C.; Shanks, Wayne C.

    2006-01-01

    The Mariana and Izu-Bonin arcs in the western Pacific are characterized by serpentinite seamounts in the forearc that provide unique windows into the mantle wedge. We present stable isotope (O, H, S, and C) data for serpentinites from Conical seamount in the Mariana forearc and S isotope data for Torishima seamount in the Izu-Bonin forearc in order to understand the compositions of fluids and temperatures of serpentinization in the mantle wedge, and to investigate the transport of sulfur from the slab to the mantle wedge. Six serpentine mineral separates have a restricted range of ??18O (6.5-8.5???). Antigorite separates have ??D values of -29.5??? to -45.5??? that reflect serpentinization within the mantle wedge whereas chrysotile has low ??D values (-51.8??? to -84.0???) as the result of re-equilibration with fluids at low temperatures. Fractionation of oxygen isotopes between serpentine and magnetite indicate serpentinization temperatures of 300-375 ??C. Two late cross-fiber chrysotile veins have higher ??18O values of 8.9??? to 10.8??? and formed at lower temperatures (as low as ???100 ??C). Aqueous fluids in equilibrium with serpentine at 300-375 ??C had ??18O = 6.5-9??? and ??D = -4??? to -26???, consistent with sediment dehydration reactions at temperatures <200 ??C in the subducting slab rather than a basaltic slab source. Three aragonite veins in metabasalt and siltstone clasts within the serpentinite flows have ??18O = 16.7-24.5???, consistent with the serpentinizing fluids at temperatures <250 ??C. ??13C values of 0.1-2.5??? suggest a source in subducting carbonate sediments. The ??34S values of sulfide in serpentinites on Conical Seamount (-6.7??? to 9.8???) result from metasomatism through variable reduction of aqueous sulfate (??34S = 14???) derived from slab sediments. Despite sulfur metasomatism, serpentinites have low sulfur contents (generally < 164 ppm) that reflect the highly depleted nature of the mantle wedge. The serpentinites are mostly

  7. Sulfur mass-independent fractionation during photolysis and photoexcitation of SO2 and CS2 and implications to the source reactions for Archean sulfur isotope anomaly

    NASA Astrophysics Data System (ADS)

    Ono, S.; Whitehill, A. R.; Oduro, H. D.

    2012-12-01

    Signatures of sulfur mass-independent fractionations (S-MIF) in Archean sedimentary rocks provide critical constraints on the atmospheric oxygen level of an early atmosphere and documents fundamental difference in early sulfur biogeochemical cycle from that of today. Archcean sulfide and sulfate minerals often yield correlated relationships among δ34S, Δ33S and Δ36S values. Our goal is to use this S-MIF pattern to pinpoint the S-MIF source reaction(s), and to constrain early atmospheric conditions beyond the oxygen level. Such an effort may lead to a new hypothesis about the cause of the Great Oxidation Event at 2.4 Billion years ago. We will present new results of laboratory photochemical experiments that are designed to calibrate the pattern of S-MIF during the photochemistry of SO2 and CS2 as a function of UV spectrum regions, partial pressure of SO2 and CS2 (0.1 mbar and above) and total N2 pressure (0.25 to 1.0 bar). Both SO2 and CS2 exhibit high energy absorption band (190 to 220 nm) that leads to direct photolysis (SO2 → SO + O or CS2 → CS + S), and low energy band (>240 nm for SO2 and 280 nm for CS2) that excites molecules to low lying electronic states under dissociation thresholds. Broadband UV light sources (Xenon or Deuterium arc lamps) are used in combination with a series of bandpass (200±35 nm), longpass (250 or 280 nm) filters to isolate specific electronic transitions. Excited state SO2 is trapped by acetylene and excited state CS2 polymerizes in the reactor, and are collected for sulfur isotope ratio analysis. Although SO2 photolysis under 190 to 220 nm is thought to be the main Archean S-MIF source reaction, its S-MIF is characterized by high δ34S values (up to 140 ‰) and relatively low Δ36S/Δ33S values (-3.3 to -5.9) compared to Archean data (-0.9 to -1.5). Strong pSO2 dependence suggests S-MIF is primarily due to isotopologue self-shielding at least under our experimental conditions. In contrast, SO2 photoexciation under >250 nm

  8. A strategy for fast screening and identification of sulfur derivatives in medicinal Pueraria species based on the fine isotopic pattern filtering method using ultra-high-resolution mass spectrometry.

    PubMed

    Yang, Min; Zhou, Zhe; Guo, De-an

    2015-09-24

    Sulfurous compounds are commonly present in plants, fungi, and animals. Most of them were reported to possess various bioactivities. Isotopic pattern filter (IPF) is a powerful tool for screening compounds with distinct isotope pattern. Over the past decades, the IPF was used mainly to study Cl- and Br-containing compounds. To our knowledge, the algorithm was scarcely used to screen S-containing compounds, especially when combined with chromatography analyses, because the (34)S isotopic ion is drastically affected by (13)C2 and (18)O. Thus, we present a new method for a fine isotopic pattern filter (FIPF) based on the separated M + 2 ions ((12)C(x)(1)H(y)(16)O(z)(32)S(13)C2(18)O, (12)C(x+2)(1)H(y)(16)O(z+1)(34)S, tentatively named M + 2OC and M + 2S) with an ultra-high-resolution mass (100,000 FWHM @ 400 m/z) to screen sulfur derivatives in traditional Chinese medicines (TCM).This finer algorithm operates through convenient filters, including an accurate mass shift of M + 2OC and M + 2S from M and their relative intensity compared to M. The method was validated at various mass resolutions, mass accuracies, and screening thresholds of flexible elemental compositions. Using the established FIPF method, twelve S-derivatives were found in the popular medicinal used Pueraria species, and 9 of them were tentatively identified by high-resolution multiple stage mass spectrometry (HRMS(n)). The compounds were used to evaluate the sulfurous compounds' situation in commercially purchased Pueraria products. The strategy presented here provides a promising application of the IPF method in a new field. PMID:26423627

  9. Sulfur isotope effects associated with protonation of HS- and volatilization of H2S

    NASA Technical Reports Server (NTRS)

    Fry, B.; Gest, H.; Hayes, J. M.

    1986-01-01

    The isotope effects associated with: (1) formation of H2S from HS- by protonation in aqueous solution; and (2) volatilization of H2S have been experimentally determined. Both isotopic distributions in closed systems at equilibrium and differential rates of volatilization of isotopic species in open systems were measured at 22 +/- 1 degrees C. It was found that, at equilibrium aqueous H2S is enriched in 34S by 2.0 - 2.7% relative to HS- and that H2S volatilized from solution is depleted in 34S by 0.5% relative to dissolved H2S. A small kinetic isotope effect accompanying volatilization of H2S was observed in the open-system experiments.

  10. The Early Cretaceous Sulfur Isotope Record: New Data, Revised Ages, and Updated Modeling

    NASA Astrophysics Data System (ADS)

    Kristall, B.; Hurtgen, M.; Sageman, B. B.; Jacobson, A. D.

    2015-12-01

    The Early Cretaceous is a time of significant transformation with the continued break-up of Pangea, the emplacement of several LIPs, and a climatic shift from a cool greenhouse to a warm greenhouse. The timing of these major events and their relationship to seawater geochemistry (as recorded in isotope records) is critical for understanding changes in global biogeochemical cycles during this time. Within this context, recent revisions to the Cretaceous portion of the geologic timescale necessitate a reevaluation of the Cretaceous S isotope record as recorded in marine barite (Paytan et al., 2004). We present a revised Early Cretaceous S isotope record and present new δ34Sbarite data that extend the record further back in time and provide more detail during two major S isotope shifts of the Early Cretaceous. The new data maintain the major ~5‰ negative shift but raise questions on the timing and structure of this perturbation. Furthermore, recently updated estimates for global rates of marine microbial sulfate reduction (MSR) (Bowles et al., 2014) and sulfate burial during the Phanerozoic (Halevy et al., 2012) require notable revisions in the fluxes and isotopic values used to model the global S cycle. We present a revised global S cycle box model and reconstruct the evolution of the Early Cretaceous S isotope record primarily through perturbations in volcanic and hydrothermal fluxes (e.g., submarine LIPs). Changes to the weathering and pyrite burial fluxes and the global integrated fractionation factor for MSR are also used to modulate, balance, and smooth the LIP-driven perturbation. The massive evaporite burial during the Late Aptian post dates the major -5‰ shift and has little affect on the modeled S isotope composition of seawater sulfate, despite causing a major drop in sulfate concentration. The S cycle box model is coupled to a Sr cycle box model to provide additional constraints on the magnitude and timing of perturbations within the S isotope record.

  11. Measuring Sulfur Isotope Ratios from Solid Samples with the Sample Analysis at Mars Instrument and the Effects of Dead Time Corrections

    NASA Technical Reports Server (NTRS)

    Franz, H. B.; Mahaffy, P. R.; Kasprzak, W.; Lyness, E.; Raaen, E.

    2011-01-01

    The Sample Analysis at Mars (SAM) instrument suite comprises the largest science payload on the Mars Science Laboratory (MSL) "Curiosity" rover. SAM will perform chemical and isotopic analysis of volatile compounds from atmospheric and solid samples to address questions pertaining to habitability and geochemical processes on Mars. Sulfur is a key element of interest in this regard, as sulfur compounds have been detected on the Martian surface by both in situ and remote sensing techniques. Their chemical and isotopic composition can belp constrain environmental conditions and mechanisms at the time of formation. A previous study examined the capability of the SAM quadrupole mass spectrometer (QMS) to determine sulfur isotope ratios of SO2 gas from a statistical perspective. Here we discuss the development of a method for determining sulfur isotope ratios with the QMS by sampling SO2 generated from heating of solid sulfate samples in SAM's pyrolysis oven. This analysis, which was performed with the SAM breadboard system, also required development of a novel treatment of the QMS dead time to accommodate the characteristics of an aging detector.

  12. Sulfur- and lead-isotope signatures of orogenic gold mineralisation associated with the Hill End Trough, Lachlan Orogen, New South Wales, Australia

    NASA Astrophysics Data System (ADS)

    Downes, P. M.; Seccombe, P. K.; Carr, G. R.

    2008-11-01

    The Hill End Trough (HET) is a deformed middle Silurian to Early Devonian sediment-dominated rift within the northeastern Lachlan Orogen. The HET hosts the Hill End, Hargraves, Napoleon Reefs, Stuart Town and Windeyer low-sulfide orogenic gold deposits. Adjacent to the HET are the Bodangora and Gulgong gold deposits. In this study we present 91 new sulfur- and 18 new lead-isotope analyses and collate a further 25 sulfur- and 32 lead-isotopes analyses from unpublished sources for these deposits. Larger gold deposits in the HET have near 0 δ34S‰ values indicating that sulfur in these systems was sourced from a magmatic reservoir. The dominant lead isotope signature for HET-hosted deposits reflects a crustal source however some mantle-derived lead has been introduced into the HET. Sulfur- and lead-isotopic results suggest that gold was sourced from mantle-derived magmatic units beneath the HET. The study supports earlier studies at Hill End by concluding that the majority of orogenic gold mineralisation in and adjacent to the HET formed during the Early Carboniferous period.

  13. MULTIPLE ORIGINS OF NITROGEN ISOTOPIC ANOMALIES IN METEORITES AND COMETS

    SciTech Connect

    Aleon, Jerome

    2010-10-20

    Isotopic fractionation and mixing calculations compared with coupled hydrogen and nitrogen isotopic composition of organic molecules from primitive chondrites, interplanetary dust particles (IDPs), and comets C/1995 O1 (Hale-Bopp) and 81P/Wild2 reveal that meteoritic and cometary organic matter contains three different isotopic components of different origins. (1) A major component of carbonaceous chondrites, IDPs, and comets Hale-Bopp and Wild2 shows correlated H and N isotopic compositions attributable to isotope exchange between an organic matter of solar composition and a reservoir formed by ion-molecule reactions at T < 25 K under conditions where competing reactions are strongly inhibited, possibly in the final evolutionary stages of the presolar cloud core, or more likely in the coldest outer regions of the solar protoplanetary disk. (2) In carbonaceous chondrites, IDPs, and comet Wild2, this component is mixed with a {sup 15}N-rich component having identical {sup 15}N and D enrichments relative to the protosolar gas. Temperatures > 100 K deduced from the low D/H ratio and an anti-correlation between the abundance of this component and meteoritic age indicate a late origin in the solar protoplanetary disk. N{sub 2} self-shielding and the non-thermal nucleosynthesis of {sup 15}N upon irradiation are possible but unlikely sources of this component, and a chemical origin is preferred. (3) An interstellar component with highly fractionated hydrogen isotopes and unfractionated nitrogen isotopes is present in ordinary chondrites. A dominantly solar origin of D and {sup 15}N excesses in primitive solar system bodies shows that isotopic anomalies do not necessarily fingerprint an interstellar origin and implies that only a very small fraction of volatile interstellar matter survived the events of solar system formation.

  14. The first data on mass-independent fractionation of sulfur isotopes in sulfides from rocks of the eastern part of the Fennoscandian Shield

    NASA Astrophysics Data System (ADS)

    Ignat'ev, A. V.; Khanchuk, A. I.; Vysotskii, S. V.; Velivetskaya, T. A.; Levitskii, V. I.; Terekhov, E. N.

    2016-08-01

    The first data on the multi-isotope composition of sulfur (32S, 33S, 34S) in samples from the Fennoscandian Shield were obtained by the laser local method. An anomalous concentration of the stable isotope 33S was registered in some samples. Δ33S ranges from-0.45 to +0.24‰, which indicates the mass-independent fractionation of S isotopes and provides evidence for the processes of primarily sedimentary accumulation of sulfides in the Archean oxygen-free atmosphere.

  15. Investigation of diachronic dietary patterns on the islands of Ibiza and Formentera, Spain: evidence from sulfur stable isotope ratio analysis.

    PubMed

    Nehlich, Olaf; Fuller, Benjamin T; Márquez-Grant, Nicholas; Richards, Michael P

    2012-09-01

    We present sulfur isotope ratio measurements of bone collagen from animals (n = 75) and humans (n = 120) from five sites dating to four chronological periods (Chalcolithic, Punic, Late Antiquity-Early Byzantine, and Islamic) from the Balearic Islands of Ibiza and Formentera, Spain. This study is a follow up to previously published δ(13)C and δ(15)N values by [Fuller et al.: Am J Phys Anthropol 143 (2010) 512-522] and focuses on using δ(34)S values to better understand the dietary patterns of these populations through time and to possibly identify immigrants to these islands. The range of δ(34)S values (10.5-17.8‰) observed for the animals was relatively broad, which suggests that a significant sea spray effect has added marine sulfates to the soils of Formentera and Ibiza. The mean δ(34)S values of the different human populations were found to be: Chalcolithic (16.5 ± 1.4‰), Punic rural (13.6 ± 1.7‰), Punic urban (12.9 ± 1.8‰), Late Antiquity-Early Byzantine (12.3 ± 2.1‰), and Islamic (9.1 ± 2.7‰). These human δ(34)S results are similar to the animal data, a finding that supports the notion that there was little marine protein consumption by these societies and that the diet was mainly based on terrestrial resources. During the Punic and Late Antiquity-Early Byzantine periods the δ(34)S values were used to identify individuals in the population who likely were not born or raised on the islands. In addition, 18 of the 20 individuals analyzed from the Islamic period have δ(34)S values that indicate that they were immigrants to Ibiza who died before acquiring the new local sulfur isotopic signature.

  16. Mineralogic, fluid inclusion, and sulfur isotope evidence for the genesis of Sechangi lead-zinc (-copper) deposit, Eastern Iran

    NASA Astrophysics Data System (ADS)

    Malekzadeh Shafaroudi, Azadeh; Karimpour, Mohammad Hassan

    2015-07-01

    The Sechangi lead-zinc (-copper) deposit lies in the Lut block metallogenic province of Eastern Iran. This deposit consists of ore-bearing vein emplaced along fault zone and hosted by Late Eocene monzonite porphyry. Hydrothermal alteration minerals developed in the wall rock include quartz, kaolinite, illite, and calcite. Microscopic studies reveal that the vein contains galena and sphalerite with minor chalcopyrite and pyrite as hypogene minerals and cerussite, anglesite, covellite, malachite, hematite, and goethite as secondary minerals. Fluorite and quartz are the dominant gangue minerals and show a close relationship with sulfide mineralization. Calculated δ34S values for the ore fluid vary between -9.9‰ and -5.9‰. Sulfur isotopic compositions suggest that the ore-forming aqueous solutions were derived from magmatic source and mixed with isotopically light sulfur, probably leached from the volcanic and plutonic country rocks. Microthermometric study of fluid inclusions indicates homogenization temperatures of 151-352 °C. Salinities of ore-forming fluids ranged from 0.2 to 16.5 wt.% NaCl equivalent. The ore-forming fluids of the Sechangi deposit are medium- to low-temperature and salinity. Fluid mixing may have played an important role during Pb-Zn (-Cu) mineralization. The key factors allowing for metal transport and precipitation during ore formation include the sourcing of magmatic fluids with high contents of metallogenic elements and the mixing of these hydrothermal fluids with meteoric waters resulting in the formation of deposit. In terms of the genetic type of deposit, the Sechangi is classified as a volcanic-subvolcanic hydrothermal-related vein deposit.

  17. Mineralogical and sulfur isotopic evidence for the incursion of evaporites in the Jinshandian skarn Fe deposit, Edong district, Eastern China

    NASA Astrophysics Data System (ADS)

    Zhu, Qiaoqiao; Xie, Guiqing; Mao, Jingwen; Li, Wei; Li, Yanhe; Wang, Jian; Zhang, Ping

    2015-12-01

    Evaporites have played important role in the formation of diverse metallic ore deposits, especially in the case of magmatic-hydrothermal deposits. However, the relationship between evaporites and skarn Fe deposit remains poorly constrained. In this contribution, we present new sulfur isotope data of pyrite, as well as the composition of halogen-rich minerals (scapolite and amphibole) in the Jinshandian skarn Fe deposit. The data are used to evaluate the evidence for incursion of evaporites in the skarn Fe deposit. The δ34S values for pyrite from the early and late retrograde stage range from +17.4‰ to +18.7‰ (n = 4) and +16.4‰ to +19.4‰ (n = 13), respectively. Both these values are markedly heavier than the common δ34S values of sulfides from magmatic-hydrothermal fluid, indicating that sulfur in the Jinshandian ore-forming system was mostly derived from evaporites. Compared to the amphibole from endoskarn, the scapolite and amphibole from exoskarn show high Cl content up to 4.04% and 3.01%, respectively, suggesting that the hydrothermal fluid with high NaCl content was probably derived from evaporites. The amphiboles from endoskarn are more enriched in F which is probably of magmatic in origin. The data presented in our study suggest that the hydrothermal system of the Jinshandian skarn Fe deposit probably experienced significant incursion of evaporites before or during the late prograde stage.

  18. A preliminary study on sulfate reduction bacteria behaviors in groundwater by sulfur and carbon isotopes: a case study in Jiaozuo City, China.

    PubMed

    Zhang, Dong; Liu, Congqiang

    2014-12-01

    Inorganic pollutants in groundwater, such as sulfate and nitrate, have been a serious problem in China for decades. These pollutants are difficult to be removed because of their high solubility and ease of transport in subsurface environment. It had been found that microorganism could be one of the most feasible methods for inorganic pollutant elimination. During the process of degradation, some microorganisms can utilize sulfur and nitrogen in sulfate and nitrate forms, respectively, as energy sources. Meanwhile, significant variations of sulfur stable isotope ratios happened. Therefore sulfur isotope can be used as a good indicator for pollutant degradation and microbial activities. Shallow groundwater (SGW), deep groundwater (DGW), and surface water (SFW) were investigated in alluvial plain in Jiaozuo City, China. The results of hydrochemical analysis indicated that K(+), Na(+), and HCO3(-) were dominant ions in DGW, Mg(2+) and HCO3(-) were dominant ions in SGW, and Ca(2+) and HCO3 (-) were dominant in SFW except for LR sample. A wide variation of δ (34)SSO4 values ranging from + 7.3 to +23.6‰ had been observed for all water samples, with a mean value of +20.7, +12.6 and +10.0‰ for DGW, SGW, and SFW respectively. At the same time, δ(13)C values of dissolved inorganic carbon (DIC) ranged from -12.4 to -5.7‰, with a mean value of -7.5, -9.0, and -9.6‰ for DGW, SGW, and SFW, respectively. The microbial degradation processes resulted in significant sulfur isotope fractionations in DGW. Organic carbon was utilized by bacteria and transferred into inorganic carbon, leading to negative fractionation of carbon isotopes. Thus the variations in stable isotope ratios of sulfur and carbon in groundwater can be used as good indicators for understanding of the relationship between bacteria behaviors and sulfate degradation. PMID:25150982

  19. Stable sulfur and carbon isotope investigations of pore-water and solid-phase compounds in sediments of the Chapopote Asphalt Volcano, southern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Wilhelm, T.; Bruechert, V.; Pape, T.; Schubotz, F.; Kasten, S.

    2007-05-01

    During R/V Meteor cruise M67 2a/b (March-April 2006) to the Asphalt Volcanoes of the southern Gulf of Mexico two gravity cores were retrieved from the central depression of the Chapopote Knoll which contained viscous oil/asphalt a few meters below the sediment surface. Also several push cores were taken with the remotely operated vehicle (ROV) QUEST at sites where oil/asphalt reached closely below the sediment surface. From these cores solid-phase and pore-water samples were taken for on-board and subsequent shore-based analyses. Together with a core taken from a background site which is not influenced by asphalt/oil seepage these sediment and pore water samples are currently subject to detailed analyses of (1) the stable sulfur isotopic composition of both dissolved (sulfate and sulfide) and solid-phase (iron monosulfides, pyrite) sulfur compounds, and (2) the composition and stable carbon isotopic signatures of hydrocarbon gases. The major aims of these investigations are to identify whether and to which extent the upward migration of oil, asphalt and gas (1) stimulates biogeochemical processes and turn-over rates, and (2) influences the stable sulfur isotopic signatures of both dissolved and solid phase sulfur compounds. Furthermore, we seek to determine the potential of these - possibly unusual - stable sulfur isotopic signals of solid-phase sulfides to reconstruct hydrocarbon seepage in older geological records and to elucidate how the composition and the stable carbon isotopic signatures of the hydrocarbon gases are altered by the action of typical chemosynthetic communities thriving at these sites.

  20. Interchange for Joint Research Entitled: Measurement of Stable Nitrogen and Sulfur Isotopes

    NASA Technical Reports Server (NTRS)

    Becker, Joseph F.; Valentin, Jose

    1997-01-01

    Viking measurements of the Martian atmosphere indicate a value of N-15/N-14 which is markedly greater than that found in Earth's atmosphere. These isotopic measurements provide a powerful diagnostic tool which may be used to derive valuable information regarding the past history of Mars and they have been used to place important constraints on the evolution of Mars' atmosphere. Initial partial pressures of nitrogen, outgassing rates, and integrated deposition of nitrogen into minerals have been calculated from this important atmospheric data (McElroy et al., 1976 and 1977; Fox and Dalgarno, 1983). The greater precision obtained in laser spectrometer isotopic measurements compared to the Viking data will greatly improve these calculated values. It has also been proposed that the N-15/N-14 value in Mars' atmosphere has increased monotonically over time (McElroy et al., 1977; Fox and Dalgarno, 1983; Wallis, 1989) owing to preferential escape of atmospheric 14N to space. Nitrogen isotopic ratios might be used to identify relatively ancient crustal rocks (R. Mancinelli, personal communication), and perhaps determine relative aces of surface samples. As a first step in successfully measuring nitrogen isotopes optically we have demonstrated the measurement of 15NI14N to a precision of 0.1% (See Figures 1-4) using a tunable diode laser and an available gas (N-,O) with spectral lines in the 2188 cm-1 region. The sample and reference gas cells contained gases of identical isotopic composition so that the 15NI14N absorption ratio determined from the sample cell, when divided by the 15NI14N absorption ratio determined from the reference cell, should yield an ideal value of unity. The average measured value of this "ratio of ratios" was 0.9983 with a standard deviation (20 values) of 0.0010. This corresponds to a precision of 0.1% (1 per mil) for nitrogen isotopes, a value sufficiently precise to provide important isotopic data of interest to exobiologists. The precision

  1. Mineralogical and Sulfur Isotopic Study on Volcanic Ash of the 2014 Eruption at Ontake Volcano, Central Honshu, Japan

    NASA Astrophysics Data System (ADS)

    Imura, T.; Minami, Y.; Ohba, T.; Takahashi, R.; Imai, A.; Hayashi, S.

    2015-12-01

    Ontake volcano erupted on 27th September 2014. Components in fallout samples were analyzed with microscope, XRD, and SEM-EDS. Pyrophyllite, smectite, muscovite, kaoline group minerals, quartz, cristobalite, tridymite, pyrite, alunite, gypsum and anhydrite were identified from bulk samples. Coarse ash fraction (> 125 µm) consists mainly of siliceous fragments that are intensely altered and contain pyrite and rutile. Weakly-altered dark-gray volcanic rock fragments are also contained. Fine fraction is abundant in euhedral free crystals of alunite and gypsum and aggregates of silica minerals. The 34S/32S ratios of bulk ash samples were analyzed for sulfur leached by water (water-soluble sulfate), gastric (HCl-soluble sulfate), and HNO3 (sulfide). Gastric and HNO3 leaching methods were applied to coarse fraction too. The bulk δ34SCDT compositions of water-soluble sulfate, HCl-soluble sulfate and sulfide were +14.7 ‰, +15.7 ‰, and -4.7 ‰, respectively. Those of HCl-soluble sulfate and sulfide in coarse fraction were +9.1 ‰ and -4.3 ‰, respectively. Paragenesis of quartz and pyrophyllite in single grain implies hydrothermal alteration by hot (> 230 °C), acidic fluid in the sub-volcanic system. The sulfur isotope geothermometry (Ohmoto and Rye, 1979) applied to the pair of water-soluble sulfate and bulk sulfide resulted in 306 °C. Similar temperature (ca. 296 °C) was estimated for the pair of HCl-soluble sulfate and sulfide in bulk ash. The mineralogy and sulfur isotopic study indicate that the 2014 Ontake eruption was derived from an acidic high-temperature (ca. 300 °C) sub-volcanic hydrothermal fluid. However, the estimated temperature for the pair of HCl-soluble sulfate and sulfide from coarse fraction resulted in higher temperature (ca. 482 °C). The coarse fraction preserved the past temperature record of the hydrothermal fluid, because the coarse lithic fragments were derived from pre-existing altered rocks.

  2. SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE

    SciTech Connect

    Xu, Yuchen; Zinner, Ernst; Gallino, Roberto; Heger, Alexander; Pignatari, Marco; Lin, Yangting

    2015-02-01

    We report C, Si, N, S, Mg-Al, and Ca-Ti isotopic compositions of presolar silicon carbide (SiC) grains from the SiC-rich KJE size fraction (0.5-0.8 μm) of the Murchison meteorite. One thousand one hundred thirteen SiC grains were identified based on their C and Si isotopic ratios. Mainstream, AB, C, X, Y, and Z subtypes of SiC, and X-type silicon nitride (Si{sub 3}N{sub 4}) account for 81.4%, 5.7%, 0.1%, 1.5%, 5.8%, 4.9%, and 0.4%, respectively. Twenty-five grains with unusual Si isotopic ratios, including one C grain, 16 X grains, 1 Y grain, 5 Z grains, and 2 X-type Si{sub 3}N{sub 4} grains were selected for N, S, Mg-Al, and Ca-Ti isotopic analysis. The C grain is highly enriched in {sup 29}Si and {sup 30}Si (δ{sup 29}Si = 1345‰ ± 19‰, δ{sup 30}Si = 1272‰ ± 19‰). It has a huge {sup 32}S excess, larger than any seen before, and larger than that predicted for the Si/S supernova (SN) zone, providing evidence against the elemental fractionation model by Hoppe et al. Two SN models investigated here present a more satisfying explanation in terms of a radiogenic origin of {sup 32}S from the decay of short-lived {sup 32}Si (τ{sub 1/2} = 153 yr). Silicon-32 as well as {sup 29}Si and {sup 30}Si can be produced in SNe by short neutron bursts; evidence for initial {sup 44}Ti (τ{sub 1/2} = 60 yr) in the C grain is additional evidence for an SN origin. The X grains have marginal {sup 32}S excesses, much smaller than expected from their large {sup 28}Si excesses. Similarly, the Y and Z grains do not show the S-isotopic anomalies expected from their large Si isotopic anomalies. Low intrinsic S contents and contamination with isotopically normal S are the most likely explanations.

  3. Sulfur Isotopic Compositions of Submicrometer SiC Grains from the Murchison Meteorite

    NASA Astrophysics Data System (ADS)

    Xu, Yuchen; Zinner, Ernst; Gallino, Roberto; Heger, Alexander; Pignatari, Marco; Lin, Yangting

    2015-02-01

    We report C, Si, N, S, Mg-Al, and Ca-Ti isotopic compositions of presolar silicon carbide (SiC) grains from the SiC-rich KJE size fraction (0.5-0.8 μm) of the Murchison meteorite. One thousand one hundred thirteen SiC grains were identified based on their C and Si isotopic ratios. Mainstream, AB, C, X, Y, and Z subtypes of SiC, and X-type silicon nitride (Si3N4) account for 81.4%, 5.7%, 0.1%, 1.5%, 5.8%, 4.9%, and 0.4%, respectively. Twenty-five grains with unusual Si isotopic ratios, including one C grain, 16 X grains, 1 Y grain, 5 Z grains, and 2 X-type Si3N4 grains were selected for N, S, Mg-Al, and Ca-Ti isotopic analysis. The C grain is highly enriched in 29Si and 30Si (δ29Si = 1345‰ ± 19‰, δ30Si = 1272‰ ± 19‰). It has a huge 32S excess, larger than any seen before, and larger than that predicted for the Si/S supernova (SN) zone, providing evidence against the elemental fractionation model by Hoppe et al. Two SN models investigated here present a more satisfying explanation in terms of a radiogenic origin of 32S from the decay of short-lived 32Si (τ1/2 = 153 yr). Silicon-32 as well as 29Si and 30Si can be produced in SNe by short neutron bursts; evidence for initial 44Ti (τ1/2 = 60 yr) in the C grain is additional evidence for an SN origin. The X grains have marginal 32S excesses, much smaller than expected from their large 28Si excesses. Similarly, the Y and Z grains do not show the S-isotopic anomalies expected from their large Si isotopic anomalies. Low intrinsic S contents and contamination with isotopically normal S are the most likely explanations.

  4. Extreme variation of sulfur isotopic compositions in pyrite from the Qiuling sediment-hosted gold deposit, West Qinling orogen, central China: an in situ SIMS study with implications for the source of sulfur

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Li, Xian-hua; Li, Jian-wei; Hofstra, Albert H.; Liu, Yu; Koenig, Alan E.

    2015-08-01

    High spatial resolution textural (scanning electron microscope (SEM)), chemical (electron microprobe (EMP)) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)), and sulfur isotopic (secondary ion mass spectrometry (SIMS)) analyses of pyrite from the Qiuling sediment-hosted gold deposit (232 ± 4 Ma) in the West Qinling orogen, central China were conducted to distinguish pyrite types and gain insights into the source and evolution of sulfur in hydrothermal fluids. The results reveal an enormous variation (-27.1 to +69.6 ‰) in sulfur isotopic composition of pyrite deposited during three paragenetic stages. Pre-ore framboidal pyrite, which is characterized by low concentrations of As, Au, Cu, Co, and Ni, has negative δ34S values of -27.1 to -7.6 ‰ that are interpreted in terms of bacterial reduction of marine sulfate during sedimentation and diagenesis of the Paleozoic carbonate and clastic sequences, the predominant lithologies in the deposit area, and the most important hosts of many sediment-hosted gold deposits throughout the West Qinling orogen. The ore-stage hydrothermal pyrite contains high concentrations of Au, As, Cu, Sb, Tl, and Bi and has a relatively narrow range of positive δ34S values ranging from +8.1 to +15.2 ‰. The sulfur isotope data are comparable to those of ore pyrite from many Triassic orogenic gold deposits and Paleozoic sedimentary exhalative (SEDEX) Pb-Zn deposits in the West Qinling orogen, both being hosted mainly in the Devonian sequence. This similarity indicates that sulfur, responsible for the auriferous pyrite at Qiuling, was largely derived from the metamorphic devolatization of Paleozoic marine sedimentary rocks. Post-ore-stage pyrite, which is significantly enriched in Co and Ni but depleted in Au and As, has unusually high δ34S values ranging from +37.4 to +69.6 ‰, that are interpreted to result from thermochemical reduction of evaporite sulfates in underlying Cambrian sedimentary rocks with very

  5. Sources and Cycling of Dissolved Organic Matter in the Sacramento - San Joaquin Delta, California, Using Carbon, Nitrogen, and Sulfur Isotopes

    NASA Astrophysics Data System (ADS)

    Silva, S. R.; Kendall, C.; Doctor, D. H.; Bergamaschi, B. A.; Fram, M. S.; Kraus, T.

    2006-12-01

    An important water quality concern of the Sacramento-San Joaquin Delta portion of the Calfed Bay-Delta restoration program is the generation of disinfection byproducts (DBP) as a result of chlorination or ozonation of San Francisco Bay Delta drinking water. One means of reducing DBPs is through monitoring and control of water sources from the various delta environments entering the California aqueduct with the objective of reducing the quantity of dissolved organic matter (DOM) and lowering the fraction with the highest DBP formation potential. The purpose of this study is to investigate the use of carbon, nitrogen, and sulfur isotopic compositions of DOM to help differentiate DOM sources and interpret seasonal variations. For this purpose, water samples collected from five general delta environments between December 1999 and June 2001 were analyzed for d13C, d15N, and d34S of DOM as well as for various chemical and optical properties. Monthly averages of d13C and d15N values for DOM retained on XAD-4 and XAD-8 resins show distinctive compositions for island drain and wetland environments throughout the year which reflect the agriculturally- related terrestrial sources of DOM from island drains, and the aquatic sources for the wetland areas. On average, the d13C values of DOM from open water (flooded island) environments, channels, and the Sacramento River water are indistinguishable from each other from spring through fall and show a progressive increase in d13C, which is likely controlled by the cycle of aquatic production through the growing season. The isotopic values from these environments diverge in the winter reflecting a change in the relative importance of the various mechanisms (sources and cycling) controlling DOM production. Sulfur isotopes show both the effects of sulfate reduction and the influence of seawater sulfate on local biota. The d13C, d15N, and d34S values show a number of correlations related to both environment and season, reflecting the

  6. The mineralogy and the isotopic composition of sulfur in hydrothermal sulfide/sulfate deposits on the East Pacific Rise, 21 deg N latitude

    NASA Technical Reports Server (NTRS)

    Styrt, M. M.; Brackmann, A. J.; Holland, H. D.; Clark, B. C.; Pisutha-Arnond, V.; Eldridge, C. S.; Ohmoto, H.

    1981-01-01

    The mineralogy and isotopic composition of sulfur found in hydrothermal deposits associated with five groups of vents along the ridge axis of the East Pacific Rise near 21 deg N latitude are investigated. Solid samples of mixed sulfides and sulfates from mounds, chimneys and the surrounding sediment as well as fresh basaltic glass were examined with a portable X-ray fluorescence spectrometer and by scanning electron microscopy, X-ray diffractometry, and electron microprobe analysis. For the three vents of exit temperature close to 350 C, the chimneys are found to be rich in copper sulfides, while for those of temperatures around 300 C, zinc sulfide is found to predominate. The major sulfides found in the chimneys include wurtzite, chalcopyrite, pyrite and cubanite, with anhydrite the dominant sulfate. Significant mineralogical differences are found between active and inactive vents. The isotopic composition of sulfur in anhydrites from active vents is observed to be close to that of sea water and consistent with a derivation from sea water sulfate. The isotopic composition of sulfur in the sulfide minerals is explained in terms of precipitation from solutions with reduced sulfur derived from basalts or basaltic magmas, and sea water sulfate. Finally, the deposits are interpreted as the results of the mixing of H2S-dominated hydrothermal fluids with cold sea water near the sea floor.

  7. Elucidating microbial processes in nitrate- and sulfate-reducing systems using sulfur and oxygen isotope ratios: The example of oil reservoir souring control

    NASA Astrophysics Data System (ADS)

    Hubert, Casey; Voordouw, Gerrit; Mayer, Bernhard

    2009-07-01

    Sulfate-reducing bacteria (SRB) are ubiquitous in anoxic environments where they couple the oxidation of organic compounds to the production of hydrogen sulfide. This can be problematic for various industries including oil production where reservoir "souring" (the generation of H 2S) requires corrective actions. Nitrate or nitrite injection into sour oil fields can promote SRB control by stimulating organotrophic nitrate- or nitrite-reducing bacteria (O-NRB) that out-compete SRB for electron donors (biocompetitive exclusion), and/or by lithotrophic nitrate- or nitrite-reducing sulfide oxidizing bacteria (NR-SOB) that remove H 2S directly. Sulfur and oxygen isotope ratios of sulfide and sulfate were monitored in batch cultures and sulfidic bioreactors to evaluate mitigation of SRB activities by nitrate or nitrite injection. Sulfate reduction in batch cultures of Desulfovibrio sp. strain Lac15 indicated typical Rayleigh-type fractionation of sulfur isotopes during bacterial sulfate reduction (BSR) with lactate, whereas oxygen isotope ratios in unreacted sulfate remained constant. Sulfur isotope fractionation in batch cultures of the NR-SOB Thiomicrospira sp. strain CVO was minimal during the oxidation of sulfide to sulfate, which had δ18O SO4 values similar to that of the water-oxygen. Treating an up-flow bioreactor with increasing doses of nitrate to eliminate sulfide resulted in changes in sulfur isotope ratios of sulfate and sulfide but very little variation in oxygen isotope ratios of sulfate. These observations were similar to results obtained from SRB-only, but different from those of NR-SOB-only pure culture control experiments. This suggests that biocompetitive exclusion of SRB took place in the nitrate-injected bioreactor. In two replicate bioreactors treated with nitrite, less pronounced sulfur isotope fractionation and a slight decrease in δ18O SO4 were observed. This indicated that NR-SOB played a minor role during dosing with low nitrite and that

  8. Application of Microwave-Induced Combustion and Isotope Dilution Strategies for Quantification of Sulfur in Coals via Sector-Field Inductively Coupled Plasma Mass Spectrometry.

    PubMed

    Christopher, Steven J; Vetter, Thomas W

    2016-05-01

    In recent years, microwave-induced combustion (MIC) has proved to be a robust sample preparation technique for difficult-to-digest samples containing high carbon content, especially for determination of halogens and sulfur. National Institute of Standards and Technology (NIST) has applied the MIC methodology in combination with isotope dilution analysis for sulfur determinations, representing the first-reported combination of this robust sample preparation methodology and high-accuracy quantification approach. Medium-resolution mode sector-field inductively coupled plasma mass spectrometry was invoked to avoid spectral interferences on the sulfur isotopes. The sample preparation and instrumental analysis scheme was used for the value assignment of total sulfur in Standard Reference Material (SRM) 2682c Subbituminous Coal (nominal mass fraction 0.5% sulfur). A description of the analytical procedures required is provided, along with metrological results, including an estimation of the overall method uncertainty (<1.5% relative expanded uncertainty) calculated using the IDMS measurement function and a Kragten spreadsheet approach. PMID:27032706

  9. Application of Microwave-Induced Combustion and Isotope Dilution Strategies for Quantification of Sulfur in Coals via Sector-Field Inductively Coupled Plasma Mass Spectrometry.

    PubMed

    Christopher, Steven J; Vetter, Thomas W

    2016-05-01

    In recent years, microwave-induced combustion (MIC) has proved to be a robust sample preparation technique for difficult-to-digest samples containing high carbon content, especially for determination of halogens and sulfur. National Institute of Standards and Technology (NIST) has applied the MIC methodology in combination with isotope dilution analysis for sulfur determinations, representing the first-reported combination of this robust sample preparation methodology and high-accuracy quantification approach. Medium-resolution mode sector-field inductively coupled plasma mass spectrometry was invoked to avoid spectral interferences on the sulfur isotopes. The sample preparation and instrumental analysis scheme was used for the value assignment of total sulfur in Standard Reference Material (SRM) 2682c Subbituminous Coal (nominal mass fraction 0.5% sulfur). A description of the analytical procedures required is provided, along with metrological results, including an estimation of the overall method uncertainty (<1.5% relative expanded uncertainty) calculated using the IDMS measurement function and a Kragten spreadsheet approach.

  10. Long-term variation of the source of sulfate deposition in a leeward area of Asian continent in view of sulfur isotopic composition

    NASA Astrophysics Data System (ADS)

    Ohizumi, Tsuyoshi; Take, Naoko; Inomata, Yayoi; Yagoh, Hiroaki; Endo, Tomomi; Takahashi, Masaaki; Yanahara, Kazuki; Kusakabe, Minoru

    2016-09-01

    A large emission of air pollutants from the Asian continent has caused transboundary air pollution, especially in northeastern Asia. This paper evaluates sulfate deposition at a leeward area of Asian continent, i.e., the Nagaoka observation station located along the Sea of Japan. We have monitored atmospheric sulfate deposition and its sulfur isotopic ratio for 28 years at the station. The sulfur isotopic ratios of non-sea-salt sulfate (δ34Snss) ranged from 0.0 to +6.2‰. The isotopic ratios of local emission and Chinese coal sulfur showed negative and positive values, respectively. Several statistically significant trends were detected on the deposition of non-sea-salt sulfate (nss-SO42-) during the study period. The decrease of nss-SO42- deposition since the middle of 1980s was considered to have been caused by local anthropogenic SO2 emission that showed relatively low δ34Snss values during the period. The increase of nss-SO42- deposition from the end of 1990s to the second half of 2000s was interpreted to have been caused by the change in SO2 emission in China because the δ34Snss values increased during the period with the winter values getting closer to the averaged value of Chinese coal sulfur. The decreasing trend of nss-SO42- deposition from the middle of 2000s was likely affected by reduction of Chinese SO2 emission judging from the decrease in δ34Snss values in the period. Mass balance calculations suggested that sulfur released by coal combustion in China during 1990s contributed by about 40% of annual total sulfur deposition in Nagaoka, and its contribution increased up to 60% in the middle of 2000s. The contribution turned to decrease after that peak, which was in harmony with the temporal change of emission from China.

  11. Mercury isotopic evidence for multiple mercury sources in coal from the Illinois basin.

    PubMed

    Lefticariu, Liliana; Blum, Joel D; Gleason, James D

    2011-02-15

    Coal combustion is the largest source of anthropogenic mercury (Hg) emissions to the atmosphere and, thus, has vast environmental implications. Recent developments in Hg stable isotope geochemistry offer a new tool for tracing sources and chemical transformations of anthropogenic Hg in the environment. We present here the first isotopic study of mercury in organic and inorganic constituents of four Pennsylvanian-age coal seams in the Illinois Basin, one of the main coal-producing areas in the USA. We report mass dependent isotopic variations relative to the NIST 3133 standard as δ(202)Hg and mass independent fractionation as Δ(199)Hg and Δ(201)Hg values. The data for Illinois coals show a wide range of δ(202)Hg (-0.75 to -2.68‰), Δ(201)Hg (0.04 to -0.22‰), and Δ(199)Hg (0.02 to -0.23‰). In contrast, vein pyrite from two coal seams is isotopically unfractionated relative to NIST 3133. Collectively, these data suggest that isotopically distinct Hg sources contributed to the organic and inorganic fractions of Illinois coals. The Δ(201)Hg/ Δ(199)Hg ratio of Illinois coals is 1:1, consistent with isotopic fractionation by photochemical reduction of Hg(2+) prior to deposition in coal-forming environments. The isotopic composition of Hg in pyrite is more likely derived from hydrothermal fluids that precipitated reduced sulfur in Illinois coal seams. These results demonstrate, for the first time, the potential of Hg isotopes to discriminate between syngenetic (depositional) and epigenetic (hydrothermal) sources of Hg in coal. Our findings may be useful in distinguishing among various geological processes controlling the distribution of Hg in coal and monitoring the fractions of Hg in emissions associated with organic versus inorganic components of coal.

  12. Study of thermochemical sulfate reduction mechanism using compound specific sulfur isotope analysis

    USGS Publications Warehouse

    Alexander Meshoulam,; Ellis, Geoffrey S.; Ward Said Ahmad,; Andrei Deev,; Alex L. Sessions,; Yongchun Tang,; Jess Adkins,; Liu Jinzhong,; William P. Gilhooly III,; Zeev Aizenshtat,; Alon Amrani,

    2016-01-01

    Experiments involving sparingly soluble CaSO4 show that during the second catalytic phase of TSR the rate of sulfate reduction exceeds that of sulfate dissolution. In this case, there is no apparent isotopic fractionation between source sulfate and generated H2S, as all of the available sulfate is effectively reduced at all reaction times. When CaSO4 is replaced with fully soluble Na2SO4, sulfate dissolution is no longer rate limiting and significant S-isotopic fractionation is observed. This supports the notion that CaSO4dissolution can lead to the apparent lack of fractionation between H2S and sulfate produced by TSR in nature. The S-isotopic composition of individual OSCs record information related to geochemical reactions that cannot be discerned from the δ34S values obtained from bulk phases such as H2S, oil, and sulfate minerals, and provide important mechanistic details about the overall TSR process.

  13. Stable isotope biogeochemistry of the sulfur cycle in modern marine sediments: I. Seasonal dynamics in a temperate intertidal sandy surface sediment.

    PubMed

    Böttcher, Michael; Hespenheide, Britta; Brumsack, Hans-Jürgen; Bosselmann, Katja

    2004-12-01

    A biogeochemical and stable isotope geochemical study was carried out in surface sediments of an organic-matter poor temperate intertidal sandy surface sediment (German Wadden Sea of the North Sea) to investigate the activity of sulfate-reducing bacteria and the dynamics of the vertical partitioning of sedimentary sulfur, iron, and manganese species in relation to the availability of total organic carbon (TOC) and mud contents. The contents and stable isotopic compositions ((34)S/(32)S) of total reduced inorganic sulfur species (TRIS) and dissolved sulfate were measured. Maximum oxygen penetration depths were estimated from the onset of a blackening of the sediments due to FeS accumulation and ranged from 5 to 10 mm below surface (mmbsf). A zone of relatively moderate relative organic-matter enrichment was found between 5 and 20 mmbsf leading to enhanced activities of sulfate-reducing bacteria with sulfate-reduction rates (SRR) up to 350 nmol cm(-3) d(-1). Below this zone, microbial SRR dropped significantly. Depth integrated SRR seem to depend not only on temperature but also on the availability of reactive organic matter. The sulfur-isotopic composition of TRIS was depleted in (34)S by 33-40 per thousand with respect to coexisting dissolved sulfate (constant at about +21 per thousand vs. Vienna-Canyon Diablo Troilite (V-CDT)). Since sulfate reduction is not limited by dissolved sulfate (open system), depth variations of the isotopic composition of TRIS reflect changes in overall isotope effect due to superimposed microbial and abiotic reactions. Most of the solid-phase iron and manganese was bonded to (non-reactive) heavy minerals. However, a layer of reactive Fe(III) and Mn(IV) oxi(hydroxi)des was found in the uppermost sediment section due to re-oxidation of dissolved Fe(II) and Mn(II) species at the sediment-water interface. Metal cycling below the surface is at least partially coupled to intense sulfur cycling.

  14. Sulfur isotopic compositions of individual organosulfur compounds and their genetic links in the Lower Paleozoic petroleum pools of the Tarim Basin, NW China

    NASA Astrophysics Data System (ADS)

    Cai, Chunfang; Amrani, Alon; Worden, Richard H.; Xiao, Qilin; Wang, Tiankai; Gvirtzman, Zvi; Li, Hongxia; Said-Ahmad, Ward; Jia, Lianqi

    2016-06-01

    During thermochemical sulfate reduction (TSR), H2S generated by reactions between hydrocarbons and aqueous sulfate back-reacts with remaining oil-phase compounds forming new organosulfur compounds (OSCs) that have similar δ34S values to the original sulfate. Using Compound Specific Sulfur Isotope Analysis (CSSIA) of alkylthiaadamantanes (TAs), alkyldibenzothiophenes (DBTs), alkylbenzothiophenes (BTs) and alkylthiolanes (TLs), we have here attempted to differentiate OSCs due to primary generation and those due to TSR in oils from the Tarim Basin, China. These oils were generated from Cambrian source rocks and accumulated in Cambrian and Ordovician reservoirs. Based on compound specific sulfur isotope and carbon isotope data, TAs concentrations and DBT/phenanthrene ratios, the oils fall into four groups, reflecting different extents of source rock signal, alteration by TSR, mixing events, and secondary generation of H2S. Thermally stable TAs, that were produced following TSR, rapidly dominate kerogen-derived TAs at low to moderate degrees of TSR. Less thermally stable TLs and BTs were created as soon as TSR commenced, rapidly adopted TSR-δ34S values, but they do not survive at high concentrations unless TSR is advanced and ongoing. The presence of TLs and BTs shows that TSR is still active. Secondary DBTs were produced in significant amounts, sufficient to dominate kerogen-derived DBTs, only when TSR was at an advanced extent. The difference in sulfur isotopes between (i) TLs and DBTs and (ii) BTs and DBTs and (iii) TAs and DBTs, represents the extent of TSR while the presence of TAs at greater than 20 μg/g represents the occurrence of TSR. The output of this study shows that compound specific sulfur isotopes of different organosulfur compounds, with different thermal stabilities and formation pathways, not only differentiate between oils of TSR and non-TSR origin, but can also reveal information about relative timing of secondary charge events and migration

  15. Sulfur isotopic fractionation and source appointment of PM2.5 in Nanjing region around the second session of the Youth Olympic Games

    NASA Astrophysics Data System (ADS)

    Guo, Zhaobing; Shi, Lei; Chen, Shanli; Jiang, Wenjuan; Wei, Ying; Rui, Maoling; Zeng, Gang

    2016-06-01

    Sulfur isotopic compositions (δ34S) of PM2.5 in Nanjing region were determined in order to evaluate sulfur sources of PM2.5 around the second session of the Youth Olympic Games (YOG). Meanwhile, δ34S values from different potential sources of PM2.5, such as coal combustion, vehicle exhaust, and straw burning, were synchronously measured for the first time. The results showed that PM2.5 concentrations and δ34S values were much lower during the YOG (2 August to 11 September 2014) compared to those before (6 July to 1 August 2014) and after (15 September to 20 September 2014) the YOG. δ34S values of PM2.5 were generally located in a small range of 3.5‰ to 4.6‰, suggesting a stable sulfur sources in Nanjing region around the YOG. Combining with δ34S values of potential sources and SO2, ion concentrations of PM2.5 and MODIS fire spot photos, we inferred that sulfur in PM2.5 was mainly from direct emission of coal combustion and vehicle exhaust as well as the secondary sulfate from SO2 oxidation in the atmosphere. Besides, biologic sulfur release might make a contribution to sulfur content in PM2.5. High [NO3-]/[SO42 -] ratio of PM2.5 indicated that vehicle exhaust emission was predominant over coal combustion during the YOG. In addition, we studied sulfur isotopic fractionation coefficients during SO2 oxidation to sulfate in PM2.5 and found the contribution ratio (51.3%) of SO2 homogeneous oxidation was slightly higher than that (48.7%) of SO2 heterogeneous oxidation around the YOG.

  16. Multiple Isotope Magneto Optical Trap from a single diode laser

    NASA Astrophysics Data System (ADS)

    Gomez, Eduardo; Valenzuela, Victor; Hamzeloui, Saeed; Gutierrez, Monica

    2013-05-01

    We present a simple design for a Dual Isotope Magneto Optical Trap. The system requires a single diode laser, a fiber modulator and a tapered amplifier to trap and completely control both 85Rb and 87Rb. We generate all the frequencies needed for trapping both species using the fiber intensity modulator. All the frequencies are amplified simultaneously with the tapered amplifier. The position and power of each frequency is now controlled independently on the RF rather than on the optical side. This introduces an enormous simplification for laser cooling that often requires an acousto-optic modulator for each frequency. The range of frequency changes is much bigger than what is available with acousto-optic modulators since in our case is determined by the modulator bandwidth (10 GHz). Additional isotopes can be simply added by including additional RF frequencies to the modulator and extra beams for other uses can be produced the same way. Support from CONACYT, PROMEP and UASLP.

  17. FUEL CYCLE ISOTOPE EVOLUTION BY TRANSMUTATION DYNAMICS OVER MULTIPLE RECYCLES

    SciTech Connect

    Samuel Bays; Steven Piet; Amaury Dumontier

    2010-06-01

    Because all actinides have the ability to fission appreciably in a fast neutron spectrum, these types of reactor systems are usually not associated with the buildup of higher mass actinides: curium, berkelium and californium. These higher actinides have high specific decay heat power, gamma and neutron source strengths, and are usually considered as a complication to the fuel manufacturing and transportation of fresh recycled transuranic fuel. This buildup issue has been studied widely for thermal reactor fuels. However, recent studies have shown that the transmutation physics associated with "gateway isotopes" dictates Cm-Bk-Cf buildup, even in fast burner reactors. Assuming a symbiotic fuel relationship with light water reactors (LWR), Pu-242 and Am-243 are formed in the LWRs and then are externally fed to the fast reactor as part of its overall transuranic fuel supply. These isotopes are created much more readily in a thermal than in fast spectrum systems due to the differences in the fast fission (i.e., above the fission threshold for non-fissile actinides) contribution. In a strictly breeding fast reactor this dependency on LWR transuranics would not exist, and thus avoids the introduction of LWR derived gateway isotopes into the fast reactor system. However in a transuranic burning fast reactor, the external supply of these gateway isotopes behaves as an external driving force towards the creation and build-up of Cm-Bk-Cf in the fuel cycle. It was found that though the Cm-Bk-Cf concentration in the equilibrium fuel cycle is dictated by the fast neutron spectrum, the time required to reach that equilibrium concentration is dictated by recycle, transmutation and decay storage dynamics.

  18. Multiple stable oxygen isotopic studies of atmospheric sulfate: A new quantitative way to understand sulfate formation processes in the atmosphere

    NASA Astrophysics Data System (ADS)

    Lee, Charles Chi-Woo

    2000-11-01

    Sulfate is an important trace species in the Earth's atmosphere because of its roles in numerous atmospheric processes. In addition to its inherent light-scattering properties, sulfate can serve as cloud condensation nucleus (CCN), affecting cloud formation as well as microphysical properties of clouds. Consequently, atmospheric sulfate species influence the global radiative energy balance. Sulfate is known to increase acidity of rainwater with negative consequences in both natural and urban environments. In addition, aerosol sulfate (<=2.5 μm) is respirable and poses a threat to human health as a potential carrier of toxic pollutants through the respiratory tract. Despite intense investigative effort, uncertainty regarding the relative significance of gas and aqueous phase oxidation pathways still remains. Acquisition of such information is important because the lifetime and transport of S(IV) species and sulfate aerosols are influenced by the oxidative pathways. In addition, sulfate formation processes affect the aerosol size distribution, which ultimately influences radiative properties of atmospheric aerosols. Therefore, the budgetary information of the sulfur cycle, as well as the radiative effects of sulfate on global climate variation, can be attained from better quantitative understanding of in situ sulfate formation processes in the atmosphere. Multiple stable oxygen isotopic studies of atmospheric sulfate are presented as a new tool to better comprehend the atmospheric sulfate formation processes. Coupled with isotopic studies, 35S radioactivity measurements have been utilized to assess contribution of sulfate from high altitude air masses. Atmospheric sulfate (aerosols and rainwater) samples have been collected from diverse environments. Laboratory experiments of gas and aqueous phase S(IV) oxidation by various oxidants, as well as biomass burning experiments, have also been conducted. The main isotopic results from these studies are as follows: (1

  19. Multiple isotope forensics of nitrate in a wild horse poisoning incident.

    PubMed

    Michalski, Greg; Earman, Sam; Dahman, Christa; Hershey, Ronald L; Mihevc, Todd

    2010-05-20

    Multiple stable isotope analysis can be a powerful technique in forensic sciences. Oxygen and nitrogen isotopes were used to determine the source of nitrate that was responsible for the poisoning deaths of 71 wild horses in the Nevada desert. The nitrate was present in a water-filled hole known as 'the Main Lake depression.' Nitrate from the Main Lake depression had delta(18)O and delta(15)N values that were very positive (+32 per thousand, +37 per thousand), and Delta(17)O values of approximately +2 per thousand. The isotopic data suggested that the most probable source of the nitrate was nitrification of nitrogen from horse manure and urine that had leached into the pond. The delta(18)O signal suggested that extreme evaporative concentration had occurred, resulting in toxic levels of nitrate accumulating in the Main Lake depression. The study demonstrates the utility of the multiple stable isotope analysis approach for characterizing sources of nitrate.

  20. Biodegradation of hydrocarbons and biogeochemical sulfur cycling in the salt dome environment: Inferences from sulfur isotope and organic geochemical investigations of the Bahloul Formation at the Bou Grine Zn/Pb ore deposit, Tunisia

    NASA Astrophysics Data System (ADS)

    Bechtel, A.; Shieh, Y.-N.; Pervaz, M.; Püttmann, W.

    1996-08-01

    Combined organic geochemical and stable isotope (S) analyses of samples from the Cretaceous Bahloul Formation (Tunisia) provide insight to oil accumulation processes, biogeochemical alteration of hydrocarbons, microbial sulfate reduction, and mineral deposition at the flanks of the Triassic Jebel Lorbeus diapir, forming the Bou Grine Zn/Pb deposit. The sulfur isotopic composition of the metal sulfides correlates with the degree of biodegradation of hydrocarbons, with the base-metal content and with the proportion of aromatics in the organic extracts. The δ 34S-values are interpreted to reflect bacterial sulfate reduction in a more or less closed system rather than a thermogenic contribution. The extent of H 2S production by the activity of the sulfate-reducing bacteria probably was limited by the availability of sulfate, which in turn was governed by the permeability of the respective sedimentary sequence and by the distance to the anhydrite cap rock. Evidence is provided that biodegradation of hydrocarbons and microbial sulfate reduction contribute to the formation of the high-grade mineralization inside the Bahloul Formation at the contact with the salt dome cap rock. The metals probably were derived through leaching of deeper sedimentary sequences by hot hypersaline basinal brines, evolved by dissolution of salt at the flanks of the diapirs. These hot metalliferous brines are proposed to migrate up around the diapir, finally mixing with near-surface, sulfate-rich brines in the roof zone. When the fluids came in contact with the organic-rich sediments of the Bahloul Formation, the dissolved sulfate was reduced by the sulfate-reducing bacteria. Hydrocarbons generated or accumulated in the Bahloul Formation were utilized by sulfate reducers. The occurrence of high amounts of native sulfur in high-grade ore samples suggest that the production rate of H 2S by bacterial sulfate reduction exceeded its consumption by metal-sulfide precipitation. The supply of dissolved

  1. Do sulfur isotope compositions of sulfate minerals and occurrence of framboidal pyrite indicate the subvent biosphere at the Suiyo Seamount in Japan?

    NASA Astrophysics Data System (ADS)

    Kakegawa, T.

    2002-12-01

    Detailed morphological studies and sulfur isotope analyses were performed on sulfides and sulfates in the drilled core samples from the Suiyo Seamount in Japan. Petrographic studies indicate that drilled samples were extremely altered by the submarine hydrothermal process. Notable feature of the examined samples is the high abundance of sulfide (e.g., FeS2, CuFeS2, ZnS and PbS) and sulfate minerals (e.g., CaSO4, BaSO4). The euhedral shape of sulfides is most common morphology in the examined samples. Sulfur isotope compositions of these sulfides are ranging from +1 to +6 per mil, suggesting that sulfides were directly precipitated from isotopically homogeneous H2S in hydrothermal fluids. On the contrary, framboidal form of pyrite was found in subsurface samples (2 m depth) of APSK 03 site (drilled site near eastern edge of caldera wall). Detailed SEM observation indicates that the framboidal pyrite is aggregate (ca. 100 micro-meter in diameter) of small grain of pyrite crystals (5 micro-meter in diameter). Such morphological nature is quite similar to these found in the modern marine sediments. Sulfur isotope compositions of individual framboids were determined using the Nd-YAG laser microprobe system at Tohoku University. Their isotopic compositions are ranging from 1 per mil to +2 per mil and slightly lighter than these of the contemporary hydrothermal sulfides. Two possibilities are considerable for the origin of framboids: (1) biogenic origin or (2) abiogenic origin. If (1) is the case, sulfate-reducing bacteria in subvent region was responsible for the formation of framboidal pyrite. Average sulfur isotope compositions of sulfate minerals are closed to +20 per mil in entire region. This suggest that the progressive introduction of sea water sulfate into the shallow hydrothermal system. Some sulfate minerals have lighter isotopic compositions (+17 to +19 per mil) than the sea water sulfate value. These lighter values indicate the mixing process between sea

  2. Geochemical and Sulfur-Isotopic Signatures of Volcanogenic Massive Sulfide Deposits on Prince of Wales Island and Vicinity, Southeastern Alaska

    USGS Publications Warehouse

    Slack, John F.; Shanks, Wayne C.; Karl, Susan M.; Gemery, Pamela A.; Bittenbender, Peter E.; Ridley, W. Ian

    2007-01-01

    Stratabound volcanogenic massive sulfide (VMS) deposits on Prince of Wales Island and vicinity, southeastern Alaska, occur in two volcanosedimentary sequences of Late Proterozoic through Cambrian and of Ordovician through Early Silurian age. This study presents geochemical data on sulfide-rich samples, in situ laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of sulfide minerals, and sulfur-isotopic analyses of sulfides and sulfates (barite) for identifying and distinguishing between primary sea-floor signatures and later regional metamorphic overprints. These datasets are also used here in an attempt to discriminate the VMS deposits in the older Wales Group from those in the younger Moira Sound unit (new informal name). The Wales Group and its contained VMS deposits have been multiply deformed and metamorphosed from greenschist to amphibolite grade, whereas the Moira Sound unit and related VMS deposits are less deformed and generally less metamorphosed (lower to middle greenschist grade). Variations in the sulfide mineral assemblages and textures of the VMS deposits in both sequences reflect a combination of processes, including primary sea-floor mineralization and sub-sea-floor zone refining, followed by metamorphic recrystallization. Very coarse grained (>1 cm diam) sulfide minerals and abundant pyrrhotite are restricted to VMS deposits in a small area of the Wales Group, at Khayyam and Stumble-On, which record high-grade metamorphism of the sulfides. Geochemical and sulfur-isotopic data distinguish the VMS deposits in the Wales Group from those in the Moira Sound unit. Although base- and precious-metal contents vary widely in sulfide-rich samples from both sequences, samples from the Moira Sound generally have proportionately higher Ag contents relative to base metals and Au. In situ LA-ICP-MS analysis of trace elements in the sulfide minerals suggests that primary sea-floor hydrothermal signatures are preserved in some samples (for

  3. A carbon, nitrogen, and sulfur elemental and isotopic study in dated sediment cores from the Louisiana Shelf

    USGS Publications Warehouse

    Rosenbauer, R.J.; Swarzenski, P.W.; Kendall, C.; Orem, W.H.; Hostettler, F.D.; Rollog, M.E.

    2009-01-01

    Three sediment cores were collected off the Mississippi River delta on the Louisiana Shelf at sites that are variably influenced by recurring, summer-time water-column hypoxia and fluvial loadings. The cores, with established chronology, were analyzed for their respective carbon, nitrogen, and sulfur elemental and isotopic composition to examine variable organic matter inputs, and to assess the sediment record for possible evidence of hypoxic events. Sediment from site MRJ03-3, which is located close to the Mississippi Canyon and generally not influenced by summer-time hypoxia, is typical of marine sediment in that it contains mostly marine algae and fine-grained material from the erosion of terrestrial C4 plants. Sediment from site MRJ03-2, located closer to the mouth of the Mississippi River and at the periphery of the hypoxic zone (annual recurrence of summer-time hypoxia >50%), is similar in composition to core MRJ03-3, but exhibits more isotopic and elemental variability down-core, suggesting that this site is more directly influenced by river discharge. Site MRJ03-5 is located in an area of recurring hypoxia (annual recurrence >75%), and is isotopically and elementally distinct from the other two cores. The carbon and nitrogen isotopic composition of this core prior to 1960 is similar to average particulate organic matter from the lower Mississippi River, and approaches the composition of C3 plants. This site likely receives a greater input of local terrestrial organic matter to the sediment. After 1960 and to the present, a gradual shift to higher values of ??13C and ??15N and lower C:N ratios suggests that algal input to these shelf sediments increased as a result of increased productivity and hypoxia. The values of C:S and ??34S reflect site-specific processes that may be influenced by the higher likelihood of recurring seasonal hypoxia. In particular, the temporal variations in the C:S and ??34S down-core are likely caused by changes in the rate of

  4. Oxygen and sulfur isotope composition of sulfate-rich evaporite mounds at the Lewis Cliffs Ice Tongue, Transantarctic Mountains, Antarctica

    NASA Astrophysics Data System (ADS)

    Socki, R. A.; Sun, T.; Bish, D. L.; Harvey, R. P.; Tonui, E.; Bao, H.

    2009-12-01

    We report the O and S isotope compositions of massive localized deposits of sodium sulfate composed nearly entirely of the mineral thenardite (Na2SO4) and its hydrate, mirabilite (Na2SO4.10H2O) collected from evaporite mounds occurring on the glacial end moraine of the Lewis Cliff Ice Tongue, Antarctica. Mounds are typically situated near the edges of small evaporative brine lakes of unknown depths. Sulfate-rich evaporite mounds at Lewis Cliff Ice Tongue have low δ18O values (average value = -17.2‰ (VSMOW)) and anomalously high δ34S values (average value = +49.1‰ (VCDT)). O and D isotope compositions of these brine lake waters confirm that they are derived from a mixture of glacial ice and snow that underwent evaporation. The highly negative δ18O water values (-30.8‰ to -64.2‰ (VSMOW)) imply the incorporation of this water oxygen into the hydrated sulfate minerals. When coupled with the enriched 34S values, these data point to mirabilite-thenardite mound formation processes involving bacterial sulfate reduction (BSR), followed by precipitation due to evaporation of the concentrated brines. We suggest that sulfate reduction occurs either at the bottom of the evaporative brine lakes, or sub-glacially, as a result of aqueous basal glacial conditions (Alpine-style) or possibly in an as yet unidentified sub-glacial lake. Sulfate 18O is ~30‰ more positive than that of the brine lake water and implies that either 1) sulfate formed directly from the oxidation of reduced sulfur within the brine lakes below ~0°C, during which a ~30‰ fractionation of oxygen isotopes could occur between water and the produced sulfate, or 2) sulfate is derived from the residue of the BSR, but with contribution from the re-oxidation of the intermediate product of BSR, sulfite. Oxygen isotopic exchange occurs between sulfite and ambient water rapidly, which also could introduce ~30‰ fractionation between the water and the sulfite. In turn, the observed sulfate will carry a

  5. Implications of 3.2 Ga deep seawater from sulfur isotopic analysis of barite crystals in Pilbara, Western Australia.

    NASA Astrophysics Data System (ADS)

    Miki, T.; Kiyokawa, S.; Takahata, N.; Ishida, A.; Ito, T.; Ikehara, M.; Sano, Y.

    2015-12-01

    Sulfur isotopic (δ34S) analysis is used as one of the methods of Precambrian environmental reconstruction. It has been pointed out that δ34S fluctuations of sulfate and sulfide have close relationship with rise of oxygen level and increase in biological activity of sulfate reducing bacteria. For example, the difference of δ34S between sulfate and sulfide is small in Archean while it gets larger after evolution of oxygen level and biological activity (e.g. Canfield and Farquhar, 2009).  However, evidence of δ34S difference between sulfate and sulfide in Archean is scarce. In this study, we focused on barite and pyrite occurred at the layer in the 3.2 Ga Dixon Island Formation in coastal Pilbara terrane, Western Australia.  We found pyrites in from the bottom of the Black Chert Member to the Varicolored Chert Member of the Dixon Island Formation. Particularly, we can see pyrite layers of a few millimeters thick which make an alternate layers with black chert layers in the Varicolored Chert Member. The bulk δ34S values of these layers are -10.1~+26.8‰ (Sakamoto, 2010MS) and micro-meter scale heterogeneity of δ34S can be seen in minute spherical shell pyrite which was formed at early stage of diagenesis (Miki, 2015MS).  On the other hand, barite layers are remained in the lower part of the Black Chert Member in the Dixon Island Formation. In these layers, columnar quartz crystals were representative which are considered to be a pseudomorph of barite. Such equigranular occurrences of barite are typical character in submarine hydrothermal system (Kiyokawa et al., 2006). There exist small crystals of barite (less than 200 um in diameter) which are expected to be remnants of original barite. We performed microscale sulfur isotope analyses using a NanoSIMS.  As a preliminary result, we obtained δ34S value of +3.4~+9.1‰ (n=11). These values are similar to the reported values of barite which are considered to be a hydrothermal origin in 3.47 Ga North Pole

  6. Are there multiple mechanisms of anaerobic sulfur oxidation with ferric iron in Acidithiobacillus ferrooxidans?

    PubMed

    Kucera, Jiri; Pakostova, Eva; Lochman, Jan; Janiczek, Oldrich; Mandl, Martin

    2016-06-01

    To clarify the pathway of anaerobic sulfur oxidation coupled with dissimilatory ferric iron reduction in Acidithiobacillus ferrooxidans strain CCM 4253 cells, we monitored their energy metabolism gene transcript profiles. Several genes encoding electron transporters involved in aerobic iron and sulfur respiration were induced during anaerobic growth of ferrous iron-grown cells. Most sulfur metabolism genes were either expressed at the basal level or their expression declined. However, transcript levels of genes assumed to be responsible for processing of elemental sulfur and other sulfur intermediates were elevated at the beginning of the growth period. In contrast, genes with predicted functions in formation of hydrogen sulfide and sulfate were significantly repressed. The main proposed mechanism involves: outer membrane protein Cyc2 (assumed to function as a terminal ferric iron reductase); periplasmic electron shuttle rusticyanin; c4-type cytochrome CycA1; the inner membrane cytochrome bc1 complex I; and the quinone pool providing connection to the sulfur metabolism machinery, consisting of heterodisulfide reductase, thiosulfate:quinone oxidoreductase and tetrathionate hydrolase. However, an alternative mechanism seems to involve a high potential iron-sulfur protein Hip, c4-type cytochrome CycA2 and inner membrane cytochrome bc1 complex II. Our results conflict with findings regarding the type strain, indicating strain- or phenotype-dependent pathway variation.

  7. Are there multiple mechanisms of anaerobic sulfur oxidation with ferric iron in Acidithiobacillus ferrooxidans?

    PubMed

    Kucera, Jiri; Pakostova, Eva; Lochman, Jan; Janiczek, Oldrich; Mandl, Martin

    2016-06-01

    To clarify the pathway of anaerobic sulfur oxidation coupled with dissimilatory ferric iron reduction in Acidithiobacillus ferrooxidans strain CCM 4253 cells, we monitored their energy metabolism gene transcript profiles. Several genes encoding electron transporters involved in aerobic iron and sulfur respiration were induced during anaerobic growth of ferrous iron-grown cells. Most sulfur metabolism genes were either expressed at the basal level or their expression declined. However, transcript levels of genes assumed to be responsible for processing of elemental sulfur and other sulfur intermediates were elevated at the beginning of the growth period. In contrast, genes with predicted functions in formation of hydrogen sulfide and sulfate were significantly repressed. The main proposed mechanism involves: outer membrane protein Cyc2 (assumed to function as a terminal ferric iron reductase); periplasmic electron shuttle rusticyanin; c4-type cytochrome CycA1; the inner membrane cytochrome bc1 complex I; and the quinone pool providing connection to the sulfur metabolism machinery, consisting of heterodisulfide reductase, thiosulfate:quinone oxidoreductase and tetrathionate hydrolase. However, an alternative mechanism seems to involve a high potential iron-sulfur protein Hip, c4-type cytochrome CycA2 and inner membrane cytochrome bc1 complex II. Our results conflict with findings regarding the type strain, indicating strain- or phenotype-dependent pathway variation. PMID:26924114

  8. Sulfur Isotopes in Gas-rich Impact-Melt Glasses in Shergottites

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Hoppe, P.; Sutton, S. R.; Nyquist, Laurence E.; Huth, J.

    2010-01-01

    Large impact melt glasses in some shergottites contain huge amounts of Martian atmospheric gases and they are known as gas-rich impact-melt (GRIM) glasses. By studying the neutron-induced isotopic deficits and excesses in Sm-149 and Sm-150 isotopes resulting from Sm-149 (n,gamma) 150Sm reaction and 80Kr excesses produced by Br-79 (n,gamma) Kr-80 reaction in the GRIM glasses using mass-spectrometric techniques, it was shown that these glasses in shergottites EET79001 and Shergotty contain regolith materials irradiated by a thermal neutron fluence of approx.10(exp 15) n/sq cm near Martian surface. Also, it was shown that these glasses contain varying amounts of sulfates and sulfides based on the release patterns of SO2 (sulfate) and H2S (sulfide) using stepwise-heating mass-spectrometric techniques. Furthermore, EMPA and FE-SEM studies in basaltic-shergottite GRIM glasses EET79001, LithB (,507& ,69), Shergotty (DBS I &II), Zagami (,992 & ,994) showed positive correlation between FeO and "SO3" (sulfide + sulfate), whereas those belonging to olivine-phyric shergottites EET79001, LithA (,506, & ,77) showed positive correlation between CaO/Al2O3 and "SO3".

  9. Sulfur (34SSO4) and oxygen (18OSO4) isotopic investigation of origin of dissolved sulfate at the Lake Acıgöl, Turkey

    NASA Astrophysics Data System (ADS)

    Karaman, Muhittin; Budakoǧlu, Murat; Taşdelen, Suat

    2016-04-01

    A dual isotope method containing the sulfur (34SSO4) and oxygen (18OSO4) isotopic composition of dissolved sulfate (SO4) was used for surveying SO4 sources from lake water and springs from the Acı göl Basin. Lake Acı göl is a Na-Cl-SO4-typehypersaline lake that is bordered by sulfate-rich springs to the south. The concentration of the dissolved sulfate of the springs ranges between 34 and 1100 mg L-1, and the lake water contains an average of 22635 mg L-1dissolved sulfate. The measured dissolved sulfate value of rain during the sampling season is 36 mg L-1. The type of spring waters bordering the lake is Na-Ca-SO4-Cl-HCO3, and the others are Mg-Ca-HCO3 and Mg-Ca-Na-SO4-HCO3. The 34SSO4 and 18OSO4 isotopic compositions were checked in 19 aqueous samples. The results showed that δ34SSO4 values of the springs varied from -4.6 to +24.1‰ and δ18OSO4values from +1.8 to +13.1‰Ṡulfate rich springs feeding the lake have sulfur isotopes that range between +22.1 and +24.1‰Ṡprings at the north side of the lake contain the lowest sulfur and oxygen isotope values (δ34SSO4= -4.6‰ δ18OSO4=+1.8). The maximum δ34SSO4values are collected from borehole drilled in the western/dry part of lake area (δ34SSO4=+32.6). The variations in δ34SSO4and δ18OSO4measuredvalues of lake water were less than 2.5‰Ṫhe δ18OSO4 values of the lake range from +16.6‰ to +18.1‰ (mean = +17.4), while the δ34SSO4 values are between +25.3 and +27.5‰ (mean = +26.6). The slope of the 18OSO4 vs. 34SSO4linear relationship (R2=0.91, n=10) of the springs is 0.4, which indicates the sulfur isotopes increase rapidly relative to the oxygen isotopes. The linear relationship (R2=0.64, n=9) between 18OSO4 and 34SSO4has a negative slope value (-0.67) for lake water. This indicates the sulfur isotopes decreases rapidly relative to the oxygen isotopes. Sulfate reduction and re-oxidation control the 18OSO4 vs. 34SSO4ratio in spring and lake water. The dual isotopes of the δ34SSO4 and δ18OSO

  10. Sulfur (34SSO4) and oxygen (18OSO4) isotopic investigation of origin of dissolved sulfate at the Lake Acıgöl, Turkey

    NASA Astrophysics Data System (ADS)

    Karaman, Muhittin; Budakoǧlu, Murat; Taşdelen, Suat

    2016-04-01

    A dual isotope method containing the sulfur (34SSO4) and oxygen (18OSO4) isotopic composition of dissolved sulfate (SO4) was used for surveying SO4 sources from lake water and springs from the Acı göl Basin. Lake Acı göl is a Na-Cl-SO4-typehypersaline lake that is bordered by sulfate-rich springs to the south. The concentration of the dissolved sulfate of the springs ranges between 34 and 1100 mg L‑1, and the lake water contains an average of 22635 mg L‑1dissolved sulfate. The measured dissolved sulfate value of rain during the sampling season is 36 mg L‑1. The type of spring waters bordering the lake is Na-Ca-SO4-Cl-HCO3, and the others are Mg-Ca-HCO3 and Mg-Ca-Na-SO4-HCO3. The 34SSO4 and 18OSO4 isotopic compositions were checked in 19 aqueous samples. The results showed that δ34SSO4 values of the springs varied from -4.6 to +24.1‰ and δ18OSO4values from +1.8 to +13.1‰Ṡulfate rich springs feeding the lake have sulfur isotopes that range between +22.1 and +24.1‰Ṡprings at the north side of the lake contain the lowest sulfur and oxygen isotope values (δ34SSO4= -4.6‰ δ18OSO4=+1.8). The maximum δ34SSO4values are collected from borehole drilled in the western/dry part of lake area (δ34SSO4=+32.6). The variations in δ34SSO4and δ18OSO4measuredvalues of lake water were less than 2.5‰Ṫhe δ18OSO4 values of the lake range from +16.6‰ to +18.1‰ (mean = +17.4), while the δ34SSO4 values are between +25.3 and +27.5‰ (mean = +26.6). The slope of the 18OSO4 vs. 34SSO4linear relationship (R2=0.91, n=10) of the springs is 0.4, which indicates the sulfur isotopes increase rapidly relative to the oxygen isotopes. The linear relationship (R2=0.64, n=9) between 18OSO4 and 34SSO4has a negative slope value (-0.67) for lake water. This indicates the sulfur isotopes decreases rapidly relative to the oxygen isotopes. Sulfate reduction and re-oxidation control the 18OSO4 vs. 34SSO4ratio in spring and lake water. The dual isotopes of the δ34SSO4 and

  11. Biogeochemistry of sulfur in a sediment core from the west-central Baltic Sea: Evidence from stable isotopes and pyrite textures

    NASA Astrophysics Data System (ADS)

    Böttcher, Michael E.; Lepland, Aivo

    2000-07-01

    The biogeochemistry of the sulfur cycle in a ca. 5-m-long sediment core from the eastern slope (221 m water depth) of the Landsort Deep in the west-central Baltic Sea was investigated by analyzing the solid phase records of sulfur isotopes and pyrite textures, besides selected main and minor elements. The sediments were deposited during post-glacial history of the Baltic Sea when the basin experienced alteration of brackish (Yoldia Sea, Littorina Sea) and freshwater (Baltic Ice Lake, Ancylus Lake) conditions. The stable isotopic composition of total sulfur was analyzed as a function of depth. In selected samples pyrite (FeS 2), greigite (Fe 3S 4), and barite (BaSO 4) fractions were separated for isotope analyses. Pyrite textures were analyzed by SEM and optical microscopy. Microbial reactions associated with the oxidation of organic matter resulted in assemblages of authigenic sulfide minerals which for the post-Ancylus Lake brackish water environment are dominated by pyrite and for freshwater environments by Fe-monosulfides. The sulfur isotopic composition of the brackish water Littorina Sea sediments ( δ34S between -40 and -27‰ vs. V-CDT) is believed to be determined by cellular sulfate reduction rates and reactions involving intermediate sulfur species. The availability of reactive iron and decomposable organic matter as well as sedimentation rate and the chemocline position are important variables upon the δ34S values of sulfides in brackish water environment. The syn-depositional abundance of sulfur and organic matter, and transport of dissolved sulfur species vs. rates of microbial reactions determine δ34S in the freshwater sediments. The upper part of the Ancylus Lake sediments is sulfidized by downward diffusing H 2S and/or sulfate from overlying brackish water sediments. Minor concretionary barite formation in the freshwater sediments is most likely due to the reaction of pore water sulfate diffusing downward from brackish water sediments with barium

  12. Changes in biomarker abundances and sulfur isotopes of pyrite across the Permian Triassic (P/Tr) Schuchert Dal section (East Greenland)

    NASA Astrophysics Data System (ADS)

    Fenton, Stephen; Grice, Kliti; Twitchett, Richard J.; Böttcher, Michael E.; Looy, Cindy V.; Nabbefeld, Birgit

    2007-10-01

    In this study, we report on biomarker abundances through parts of the Permian/Triassic boundary (PTB) of Schuchert Dal (East Greenland) that contains rich marine faunal records and excellent terrestrial palynological records. Biomarker abundances and sulfur isotopes are used to correlate the series of events (including changes in element cycling and associated redox conditions of the ocean) surrounding the collapse of the marine and terrestrial ecosystems through this record of a major crisis of life on Earth during a mass extinction episode. The Upper Schuchert Dal Formation contains a low diversity palynological assemblage, ascribed to arborescent cordiaite-conifer-pteridosperm vegetation. Samples from this pre-collapse interval are characterised by high abundances of dibenzofuran (DBF), dibenzothiophene (DBT) and biphenyl. Since these compounds have similar base structures, and show comparable abundance curves, it is plausible that they probably derive from a common source. We propose that phenolic compounds of lignin of the woody plants present during this period could be the source for DBF, DBT and biphenyl. The redox conditions during this period of time also support the formation of DBF and DBT. Just above the extinction interval, there is a dramatic decrease in the abundances of DBF and DBT which occurs at the same time as a sudden change in the stable sulfur isotopic composition ( δ34S) of pyrite, indicating a change in redox conditions from oxic to anoxic/euxinic conditions. δ34S values leading up to the extinction are highly depleted in the heavy sulfur isotope (about - 40‰ vs. VCDT), whilst shortly after the extinction interval much more positive isotope values are observed (about - 25‰). An inferred change in the biogeochemical sulfur cycle is supported by facies evidence from similar neighbouring sections. It is suggested that two processes are operating closely here; 1) Changes in redox conditions and 2) extinction and/or transgression

  13. Single and multiple ionization of sulfur atoms by electron impact. [in Io plasma torus

    NASA Technical Reports Server (NTRS)

    Ziegler, D. L.; Newman, J. H.; Goeller, L. N.; Smith, K. A.; Stebbings, R. F.

    1982-01-01

    In 1979 significant concentrations of singly and multiply charged sulfur ions were observed in the Io torus. Attempts to model these observations revealed a need for new fundamental cross section data. In response, laboratory measurements of the cross-sections for single, double, triple and quadruple ionization of sulfur atoms by electron impact are presented for collision energies from threshold to 500 eV.

  14. Sulfur isotopic systematics in alteration assemblages in martian meteorite Allan Hills 84001

    SciTech Connect

    Shearer, C.K.; Layne, G.D.; Papike, J.J.; Spilde, M.N.

    1996-08-01

    ALH84001 is a coarse-grained, clastic orthopyroxenite meteorite related to the SNC meteorite group (shergottites, nakhlites, Chassigny). Superimposed upon the orthopyroxene-dominant igneous mineral assemblage is a hydrothermal signature. This hydrothermal overprint consists of carbonate assemblages occurring in spheroidal aggregates and fine-grained carbonate-sulfide vug-filling. The sulfide in this assemblage has been identified as pyrite, an unusual sulfide in meteorites. Previously, Burgess et al. (1989) reported a bulk {delta} {sup 34}S for a SNC group meteorite (Shergotty) of -0.5 {+-} 1.5%. Here, we report the first martian {delta} {sup 34}S values from individual sulfide grains. Using newly developed ion microprobe techniques, we were able to determine {delta} {sup 34}S of the pyrite in ALH84001 with a 1 {alpha} precision of better than {+-}0.5%. The {delta} {sup 34}S values for the pyrite range from +4.8 to +7.8%. Within the stated uncertainties, the pyrite from ALH84001 exhibits a real variability in {delta} {sup 34}S in this alteration assemblage. In addition, these sulfides are demonstrably enriched in {sup 34}S relative to Canon Diablo troilite and sulfides from most other meteorites. This signature implies that the planetary body represented by ALH 84001 experienced processes capable of fractionating sulphur isotopes and that hydrothermal conditions changed during pyrite precipitation (T, pH, fluid composition, etc.). These new data are not consistent with the pyrite recording either biogenic activity or atmospheric fractionation of sulphur through nonthermal escape mechanisms or oxidation processes. This study also demonstrates the usefulness of ion microprobe measurements of sulphur isotopes in constraining conditions on other planetary bodies.

  15. Sulfur isotopic systematics in alteration assemblages in martian meteorite Allan Hills 84001

    NASA Astrophysics Data System (ADS)

    Shearer, C. K.; Layne, G. D.; Papike, J. J.; Spilde, M. N.

    1996-08-01

    ALH84001 is a coarse-grained, clastic orthopyroxenite meteorite related to the SNC meteorite group ( shergottites, nakhlites, Chassigny). Superimposed upon the orthopyroxene-dominant igneous mineral assemblage is a hydrothermal signature. This hydrothermal overprint consists of carbonate assemblages occurring in spheroidal aggregates and fine-grained carbonate-sulfide vug-filling. The sulfide in this assemblage has been identified as pyrite, an unusual sulfide in meteorites. Previously, Burgess et al. (1989) reported a bulk δ 34S for a SNC group meteorite (Shergotty) of -0.5 ± 1.5‰. Here, we report the first martian δ 34S values from individual sulfide grains. Using newly developed ion microprobe techniques, we were able to determine δ 34S of the pyrite in ALH84001 with a 1 a precision of better than ±0.5‰. The δ 34S values for the pyrite range from +4.8 to +7.8‰. Within the stated uncertainties, the pyrite from ALH84001 exhibits a real variability in δ 34S in this alteration assemblage. In addition, these sulfides are demonstrably enriched in 34S relative to Canon Diablo troilite and sulfides from most other meteorites. This signature implies that the planetary body represented by ALH84001 experienced processes capable of fractionating sulphur isotopes and that hydrothermal conditions changed during pyrite precipitation (T, pH, fluid composition, etc.). The fractionated signature of the sulphur in the pyrite is most likely attributed to either conditions of pyrite precipitation (low temperature, reduced (low fo 2) and moderately alkaline (pH > 8) environment) or enrichment of fluids in 34S by surface processes (weathering or impact processes) prior to precipitation. These new data are not consistent with the pyrite recording either biogenic activity or atmospheric fractionation of sulphur through nonthermal escape mechanisms or oxidation processes. This study also demonstrates the usefulness of ion microprobe measurements of sulphur isotopes in

  16. Ground water recharge and flow characterization using multiple isotopes.

    PubMed

    Chowdhury, Ali H; Uliana, Matthew; Wade, Shirley

    2008-01-01

    Stable isotopes of delta(18)O, delta(2)H, and (13)C, radiogenic isotopes of (14)C and (3)H, and ground water chemical compositions were used to distinguish ground water, recharge areas, and possible recharge processes in an arid zone, fault-bounded alluvial aquifer. Recharge mainly occurs through exposed stream channel beds as opposed to subsurface inflow along mountain fronts. This recharge distribution pattern may also occur in other fault-bounded aquifers, with important implications for conceptualization of ground water flow systems, development of ground water models, and ground water resource management. Ground water along the mountain front near the basin margins contains low delta(18)O, (14)C (percent modern carbon [pmC]), and (3)H (tritium units [TU]), suggesting older recharge. In addition, water levels lie at greater depths, and basin-bounding faults that locally act as a flow barrier may further reduce subsurface inflow into the aquifer along the mountain front. Chemical differences in ground water composition, attributed to varying aquifer mineralogy and recharge processes, further discriminate the basin-margin and the basin-center water. Direct recharge through the indurated sandstones and mudstones in the basin center is minimal. Modern recharge in the aquifer is mainly through the broad, exposed stream channel beds containing coarse sand and gravel where ground water contains higher delta(18)O, (14)C (pmC), and (3)H (TU). Spatial differences in delta(18)O, (14)C (pmC), and (3)H (TU) and occurrences of extensive mudstones in the basin center suggest sluggish ground water movement, including local compartmentalization of the flow system.

  17. Sulfur and oxygen isotope study of the Vermont copper belt: evidence of seawater hydrothermal alteration and sulfate reduction in a high-grade metamorphic terrane

    SciTech Connect

    Shanks, W.C. III; Woodruff, L.G.; Slack, J.F.

    1985-01-01

    Massive sulfide deposits of the Orange County copper district, in east-central Vermont, consist of stratiform lenses of pyrrhotite, chalcopyrite, and minor sphalerite within amphibolite-facies rocks of Early Devonian (.) age. The deposits occur at several different stratigraphic levels. The two largest, Elizabeth and Ely, are in quartz-mica schists of the Gile Mountain Formation; the Pike Hill deposit occurs in calcareous quartz-mica schist of the underlying Waits River Formation. Two small deposits (Orange and Gove) are within the Standing Pond Volcanics, a thin tholeiitic amphibolite near the Gile Mountain-Waits River contact. The Elizabeth deposit in particularly distinctive, and contains a suite of unusual wall rocks rich in quartz, carbonate, muscovite, amphibole, phlogopite, tourmaline, spessartine, and sodic plagioclase. Sulfur isotope values at Elizabeth and Ely of 5.1 to 9.1 per thousands contrast with values for Gove (1.9 to 4.2) and Pike Hill (1.5 to 4.6). Disseminated sulfides in amphibolites of the Standing Pond Volcanics have sulfur isotope values in the range -0.1 to 1.7 per thousands, typical of MORB. These data require sulfur contributions to massive sulfide deposits both from basalt and from contemporaneous seawater sulfate sources. Whole-rock (carbonate free) oxygen isotope analyses of host lithologies range from 7.9 per thousands (Standing Pond Volcanics) to 19.9 per thousands (Waits River Formation). Detailed sampling of Elizabeth wall rocks (including those high in B, Na, Mg, Al, Si, Mn) yields a narrow range of oxygen isotope values (11.1 to 14.1); heavier values correlate with higher silica contents. Isotopically light wallrock lithologies are probably due to premetamorphic seawater hydrothermal alteration.

  18. Multiple sources of isotopic variation in a terrestrial arthropod community: challenges for disentangling food webs.

    PubMed

    Daugherty, Matthew P; Briggs, Cheryl J

    2007-08-01

    Documenting trophic links in a food web has traditionally required complex exclusion experiments coupled with extraordinarily labor-intensive direct observations of predator foraging. Newer techniques such as stable isotope analysis (SIA) may facilitate relatively quick and accurate assessments of consumer feeding behavior. Ratios of N and C isotopes are thought to be useful for determining species' trophic position (e.g., 1 degrees consumer, 2 degrees consumer, or omnivore) and their original carbon source (e.g., C3 or C4 plants; terrestrial or marine nutrients). Thus far, however, applications of stable isotopes to terrestrial arthropod food webs have suggested that high taxon-specific variation may undermine the effectiveness of this method. We applied stable isotope analysis to a pear orchard food web, in which biological control of a dominant pest, pear psylla (Cacopsylla pyricola), involves primarily generalist arthropod predators with a high frequency of omnivory. We found multiple sources of isotopic variation in this food web, including differences among plant tissues; time, stage, and taxon-specific differences among herbivores (despite similar feeding modes); and high taxon-specific variation among predators (with no clear evidence of omnivory). Collectively, these multiple sources of isotopic variation blur our view of the structure of this food web. Idiosyncrasies in consumer trophic shifts make ad hoc application of SIA to even moderately complex food webs intractable. SIA may not be a generally applicable "quick and dirty" method for delineating terrestrial food web structure-not without calibration of specific consumer food trophic shifts.

  19. First Ion Microprobe Determination Of Water And Sulfur Isotopic Ratios In Melt Inclusions Of Olivines At Mount Etna

    NASA Astrophysics Data System (ADS)

    Allard, P.; Metrich, N.; Deloule, E.; Belhadj, O.; Mandeville, C.; Spilliaert, N.

    2006-12-01

    Ion microprobe determination of the isotopic composition of magmatic volatiles preserved in crystal melt inclusions (MI), first applied to Hawaiian volcanoes [1], opens new perspectives to elucidate the source of magmas and their conditions of ascent, degassing and eruption. Here we report on the first ion microprobe isotopic analysis of water and sulfur dissolved in olivine-hosted MIs and glass embayments (40- 200 μm) in primitive alkali basaltic magma erupted from >15 km depth (400 MPa) during the 2002 flank of Mount Etna, in Sicily. The MIs, recovered from rapidly quenched explosive products, were previously analyzed for their content in dissolved H2O, CO2, S, Cl and F [2,3]. Isotopic measurements were performed at CRPG using Cameca IMS3F and IMS1270 microprobes, respectively. Calibration was made against Etna glass samples of similar composition and with known H2O-S concentrations and isotope ratios determined with mass spectrometry. δ34S (±0.7) and δD (±5-12) values are given in per mil deviations with respect to SMOW and CDT standards. The most primitive MIs representing S-undegassed magma contain 0.29-0.34 wt% S with a mean δ34S of +2.4±0.4, comparable to that of 800-1100°C Etna volcanic gases [4]. The δ34S of more evolved, S-poorer inclusions and embayments, trapped at lower pressure, track both the magma degassing process and S-removal by sulfide globule as the melt reaches sulfide-saturation. The results for water are more complex and their interpretation is still preliminary. The most pristine inclusions, trapped at >12 km depth below summit, contain 0.2-0.4 wt% CO2 and 3.2±0.3 wt% H2O with δD clustering at around -20 (range: -90 to 0). However, a second cluster of water- rich but CO2-poorer (<0.13 wt%) inclusions, trapped as magma ponds at 6-8 km depth [2], displays positive δD values of between 0 and +40. Such anomalous δD, coupled with evidence of heterogeneous gas-melt entrapment conditions, suggests deuterium enrichment mainly due to

  20. A Simplified Method for Quantifying Sulfur Mustard Adducts to Blood Proteins by Ultra-High Pressure Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry

    PubMed Central

    Pantazides, Brooke G.; Crow, Brian S.; Garton, Joshua W.; Quiñones-González, Jennifer A.; Blake, Thomas A.; Thomas, Jerry D.; Johnson, Rudolph C.

    2016-01-01

    Sulfur mustard binds to reactive cysteine residues, forming a stable sulfur-hydroxyethylthioethyl [S-HETE] adduct that can be used as a long-term biomarker of sulfur mustard exposure in humans. The digestion of sulfur mustard-exposed blood samples with proteinase K following total protein precipitation with acetone produces the tripeptide biomarker [S-HETE]-Cys-Pro-Phe. The adducted tripeptide is purified by solid phase extraction, separated by ultra-high pressure liquid chromatography, and detected by isotope dilution tandem mass spectrometry. This approach was thoroughly validated and characterized in our laboratory. The average interday relative standard deviation was ≤ 9.49%, and the range of accuracy was between 96.1-109% over a concentration range of 3.00 to 250. ng/mL with a calculated limit of detection of 1.74 ng/mL. A full 96-well plate can be processed and analyzed in 8 h which is five times faster than our previous 96-well plate method and only requires 50 µL of serum, plasma, or whole blood. Extensive ruggedness and stability studies and matrix comparisons were conducted to create a robust, easily transferrable method. As a result, a simple and high-throughput method has been developed and validated for the quantitation of sulfur mustard blood protein adducts in low volume blood specimens which should be readily adaptable for quantifying human exposures to other alkylating agents. PMID:25622494

  1. Role of evaporitic sulfates in iron skarn mineralization: a fluid inclusion and sulfur isotope study from the Xishimen deposit, Handan-Xingtai district, North China Craton

    NASA Astrophysics Data System (ADS)

    Wen, Guang; Bi, Shi-Jian; Li, Jian-Wei

    2016-08-01

    The Xishimen iron skarn deposit in the Handan-Xingtai district, North China Craton, contains 256 Mt @ 43 % Fe (up to 65 %). The mineralization is dominated by massive magnetite ore along the contact zone between the early Cretaceous Xishimen diorite stock and middle Ordovician dolomite and dolomitic limestones with numerous intercalations of evaporitic beds. Minor lenticular magnetite-dominated bodies also occur in the carbonate rocks proximal to the diorite stock. Hydrothermal alteration is characterized by extensive albitization within the diorite stock and extreme development of magnesian skarn along the contact zone consisting of diopside, forsterite, serpentine, tremolite, phlogopite, and talc. Magmatic quartz and amphibole from the diorite and hydrothermal diopside from the skarns contain abundant primary or pseudosecondary fluid inclusions, most of which have multiple daughter minerals dominated by halite, sylvite, and opaque phases. Scanning electron microscopy (SEM) and laser Raman spectrometry confirm that pyrrhotite is the predominant opaque phase in most fluid inclusions, in both the magmatic and skarn minerals. These fluid inclusions have total homogenization temperatures of 416-620 °C and calculated salinities of 42.4-74.5 wt% NaCl equiv. The fluid inclusion data thus document a high-temperature, high-salinity, ferrous iron-rich, reducing fluid exsolved from a cooling magma likely represented by the Xishimen diorite stock. Pyrite from the iron ore has δ34S values ranging from 14.0 to 18.6 ‰, which are significantly higher than typical magmatic values (δ34S = 0 ± 5 ‰). The sulfur isotope data thus indicate an external source for the sulfur, most likely from the evaporitic beds in the Ordovician carbonate sequences that have δ34S values of 24 to 29 ‰. We suggest that sulfates from the evaporitic beds have played a critically important role by oxidizing ferrous iron in the magmatic-hydrothermal fluid, leading to precipitation of massive

  2. Neutron multiplicity measurements of Cf and Fm isotopes

    SciTech Connect

    Hoffman, D.C.; Ford, G.P.; Balagna, J.P.; Veeser, L.R.

    1980-02-01

    Prompt neutrons in coincidence with the fission fragments from the spontaneous fission of /sup 250,252,254/Cf and /sup 257/Fm were measured inside a 75-cm-diameter, Gd-loaded liquid scintillation counter having a neutron-detection efficiency of about 78%. Measurements for /sup 256/Fm were done just outside the counter with an efficiency of 31%. The kinetic energies of both fission fragments and the number of neutrons for each fission event were recorded. From these data, the fragment kinetic energies and masses and the neutron multiplicity distributions were determined for /sup 250,252,254/Cf and /sup 257/Fm. Variances of neutron multiplicity distributions as a function of total fragment kinetic energy and the ratio of fragment masses have been calculated and are presented for all the nuclides studied.

  3. Multiple taxon multiple locality approach to providing oxygen isotope evidence for warm-blooded theropod dinosaurs

    NASA Astrophysics Data System (ADS)

    Fricke, Henry C.; Rogers, Raymond R.

    2000-09-01

    Oxygen isotope ratios of fossil remains of coexisting taxa from several different localities can be used to help investigate dinosaur thermoregulation. Focusing on the Late Cretaceous, oxygen isotope ratios of crocodile tooth enamel from four separate localities exhibit less of a decrease with latitude than do ratios of tooth enamel from coexisting theropod dinosaurs. A shallower latitudinal gradient for crocodiles is consistent with how oxygen isotope ratios should vary for heterothermic animals having body temperatures coupled with their environments (“cold blooded”), while a steeper gradient for theropods is consistent with how these ratios should vary for homeothermic animals having constant body temperatures independent of their environments (“warm blooded”). This inferred homoethermy in theropods is likely due to higher rates of metabolic heat production relative to crocodiles and is not an artifact of body size.

  4. Sulfur isotopic disequilibrium and fluid-rock interaction during metamorphism of sulfidic black shales from the Waterville-Augusta area, Maine, USA

    USGS Publications Warehouse

    Oliver, N.H.S.; Hoering, T.C.; Johnson, T.W.; Rumble, D.; Shanks, Wayne C.

    1992-01-01

    Sulfur isotope ratios of pyrite (py) and pyrrhotite (po) from regionally metamorphosed graphitic sulfidic schists and related rocks from south-central Maine, USA, were analysed using SO2 and SF6 techniques. There is a broad range in ??34S values for both pyrite and pyrrhotite at most outcrops, up to 8%. and overall the values are isotopically light, averaging ~ -27??? for the entire data set, suggesting that the rocks have not been grossly isotopically disturbed by regional metamorphism from their inferred organic-rich sedimentary origins. At all temperatures from chlorite to sillimanite grades, sulfide analysed from veins and blebs within the schists show predominantly disequilibrium fractionations ranging from ??34Spy-po -3.0 to +3.5???, as do matrix sulfides from rocks that attained temperatures 500??C do matrix pyrite-pyrrhotite pairs with polygonal or aligned granoblastic microstructures approach isotopic equilibrium at millimeter to centimeter scales, suggesting that the process that favoured equilibration was recrystallization accompanying metamorphism and deformation. This disequilibrium may be a function of preferential interaction of one of the phases with an infiltrating fluid, but the lack of any systematic trends in the data, particularly with both negative and positive ??34Spy-po at some outcrops, does not permit ready identification of fluid sources, fluxes, or compositions. By combining published fluid fluxes for the area and a knowledge of the mass of sulfur contained in the rocks and the inferred infiltrating fluid, it appears that sulfur should have been homogenized over at least 10's to 1000's of meters, if equilibrium had been attained between rock sulfides and an infiltrating fluid of constant composition. That this did not occur was probably due to lack of equilibration between sulfides and the fluid but may also have arisen because of channelling of fluid flow along rather than across layers, or a lack of fluid infiltration through this unit

  5. Triple-oxygen and sulfur isotopic evidence for diagenetic overprinting of carbonate-associated sulfate in Neoproterozoic samples from a drill core

    NASA Astrophysics Data System (ADS)

    Peng, Y.; Wang, W.; Pratt, L. M.; Zhou, C.; Bao, H.; Hayles, J. A.

    2014-12-01

    Carbonate-associated sulfate (CAS) is used in many studies to reconstruct the isotopic composition of ancient seawater sulfate and to infer stages in the development of Earth's oxygenated atmosphere. CAS is acid extractable and commonly is referred to as structurally substituted sulfate in carbonate minerals. Several recent studies, however, have raised concerns about sulfate overprinting during early or late diagenesis, including contamination by modern secondary atmospheric sulfate (SAS) and by sulfide oxidation during laboratory processing. To test for overprinting and contamination, we studied the isotopic composition of sulfate in a bedded carbonate succession of the Neoproterozoic Lantian Formation, South China. Materials were obtained from a drilling core (635Ma- 551Ma). Water-leachable sulfate (WLS), acid-leachable sulfate (ALS, i. e. extracted CAS), and chromium-reducible sulfur (CRS) were sequentially extracted out and triple oxygen isotopic compositions of WLS and ALS were analyzed as well as sulfur isotope of WLS, ALS, and CRS. We also analyzed the oxygen isotope of sulfate resulting from pyrite oxidation at a condition similar to the extraction of WLS and ALS in the laboratory and the δ18O value is at ~ -1.4‰ (VSMOW). The slightly negative ∆17O values of all WLS and ALS indicates that the ALS was not contaminated by sulfate of modern SAS. The WLS from the first 24 hours with consistently negative values of δ18O (about -11.0‰) and low δ34S values (about +5‰) suggests that the WLS resulted from sulfide oxidation in water with very negative δ18O values, likely glacial melt-water in the distant past, which had likely soaked the whole stratigraphy of Lantian Formation for a long time. The WLS also comprised a significant fraction of ALS because both δ18O and δ34S of ALS have wide ranges, from -6.9 to +15.8‰, and +12.7 to +31.7‰, respectively. More importantly, there is a strong positive correlation between δ18O and δ34S of ALS. Our

  6. High arsenic concentrations and enriched sulfur and oxygen isotopes in a fractured-bedrock ground-water system

    USGS Publications Warehouse

    Lipfert, G.; Sidle, W.C.; Reeve, A.S.; Ayuso, R.A.; Boyce, A.J.

    2007-01-01

    Ground water with high arsenic concentrations (up to 26.6????mol L- 1) has sulfate enriched in 34S and 18O in the fractured-bedrock, ground-water system of the Kelly's Cove watershed, Northport, Maine, USA. The ranges of sulfur and oxygen isotope values in aqueous sulfate, ??34S[SO4] and ??18O[SO4], at the Kelly's Cove watershed are + 3.4 to + 4.9??? and - 2.0 to + 6.7???, respectively. These isotope values are strikingly similar to those of the Goose River, Maine watershed which has ??34S[SO4] and ??18O[SO4] ranges of + 3.7 to + 4.6 ??? and - 2.6 to + 7.5???, respectively. In both systems, high arsenic concentrations occur with high ??34S[SO4] and ??18O[SO4] values, yet redox conditions and underlying rock types are quite different. The isotope values of sulfide minerals, ??34S[min], from four bedrock cores vary over short distances and range from - 5.1 to + 7.5???. The ??34S[SO4] values are controlled by the ??34S[min] values with minor input of atmospheric SO4. The much narrower range in ??34S[SO4] values than ??34S[min] values is probably due to sufficient ground-water mixing at a scale greater than the ??34S[min] variability. The ??34S[SO4] values are about 2??? higher than the average ??34S[min] value and fall within the range of ??34S[min] values, indicating only minor fractionation due to bacterial reduction of SO4. The highest ??18O[SO4] values were measured in the downgradient, confined, arsenic-rich ground water. High ??18O[SO4] values there cannot be due to aeration by atmospheric oxygen, but may arise from reoxidation of reduced SO4 products. The enrichment factors of ??18O in SO4 compared to H2O, + 7.2 to + 15.5???, in the Kelly's Cove ground water and the negligible 34S enrichment is very similar to those derived from experimental data of anaerobic sulfide oxidation in the presence of Mn and Fe oxides. Sea level at the Kelly's Cove watershed was approximately 80??m above present sea level about 13 000??years before present, imposing reducing

  7. The Kabanga Ni sulfide deposit, Tanzania: I. Geology, petrography, silicate rock geochemistry, and sulfur and oxygen isotopes

    NASA Astrophysics Data System (ADS)

    Maier, Wolfgang D.; Barnes, Sarah-Jane; Sarkar, Arindam; Ripley, Ed; Li, Chusi; Livesey, Tim

    2010-06-01

    ). The sulfides have heavy S isotopic signatures (δ34S wr = +10 to +24) that broadly overlap with those of the country rock sulfides, consistent with significant assimilation of external sulfur from the Karagwe-Ankolean sedimentary sequence. However, based partly on the relatively homogenous distribution of disseminated sulfides in many of the intrusive rocks, we propose that the Kabanga magmas reached sulfide saturation prior to final emplacement, in staging chambers or feeder conduits, followed by entrainment of the sulfides during continued magma ascent. Oxygen isotope data indicate that the mode of sulfide assimilation changed with time. The heavy δ18O ratios of the early magmas are consistent with ingestion of the sedimentary country rocks in bulk. The relatively light δ18O ratios of the later magmas indicate less bulk assimilation of the country rocks, but in addition the magmas selectively assimilated additional S, possibly through devolatization of the country rocks or through cannibalization of magmatic sulfides deposited in the conduits by preceding magma surges. The intrusions were tilted at ca. 1.37 Ga, during the Kibaran orogeny and associated synkinematic granite plutonism. This caused solid-state mobilization of ductile sulfides into shear zones, notably along the base of the intrusions where sulfide-hornfels breccias and lenses and layers of massive sulfides may reach a thickness of >10 m and can extend for several 10 s to >100 m away from the intrusions. These horizons represent an important exploration target for additional nickel sulfide deposits.

  8. Multiple S isotopes, zircon Hf isotopes, whole-rock Sr-Nd isotopes, and spatial variations of PGE tenors in the Jinchuan Ni-Cu-PGE deposit, NW China

    NASA Astrophysics Data System (ADS)

    Duan, Jun; Li, Chusi; Qian, Zhuangzhi; Jiao, Jiangang; Ripley, Edward M.; Feng, Yanqing

    2016-04-01

    Previous geochemical data for the Jinchuan Ni-Cu-(platinum-group elements, PGE) deposit, the single largest magmatic sulfide deposit in the world, are derived primarily from the upper parts of the deposit. This paper reports new PGE and S-Hf-Sr-Nd isotope data for the lower parts of the deposit that have become accessible for sampling by ongoing underground mining activity. New PGE data from this study, together with previous results, indicate that PGE tenors in the bulk sulfide ores of the deposit increase eastward, except for two fault-offset ore zones which occur together within the western part of the deposit. Generally, these two ore zones show depletions in IPGE (Ir, Ru, Rh) but not in PPGE (Pt, Pd) and Cu, and more fractionated olivine and Cr-spinel compositions than the rest of the deposit. These differences can be explained by a more evolved parental magma for the IPGE-depleted ore zones. The eastward increase of PGE tenors in the rest of the deposit can be explained by upgrading of preexisting sulfide liquid in a subhorizontal conduit by a new surge of magma moving through the conduit from west to east, which took place before the formation of the IPGE-depleted ore zones. The Jinchuan ultramafic rocks are characterized by elevated initial 87Sr/86Sr ratios from 0.7077 to 0.7093, negative ɛ Nd values from -9.2 to -10.5, and zircon ɛ Hf values from -4 to -7. These data indicate up to 20 % of crustal contamination in the Jinchuan magma. Four of nine multiple sulfur isotope analyses for the Jinchuan deposit show anomalous ∆33S values varying from 0.12 to 2.67 ‰. These results, together with elevated δ34S values (>2 ‰) for some of the samples analyzed previously by other researchers, indicate the involvement of external sulfur from Archean and Proterozoic sedimentary rocks. Modeling results based on our olivine data and magma compositions estimated previously by other researchers indicate that fractional crystallization did not play a major role in

  9. Evaluations of the trans-sulfuration pathway in multiple liver toxicity studies

    SciTech Connect

    Schnackenberg, Laura K. Chen Minjun; Sun, Jinchun; Holland, Ricky D.; Dragan, Yvonne; Tong Weida; Welsh, William; Beger, Richard D.

    2009-02-15

    Drug-induced liver injury has been associated with the generation of reactive metabolites, which are primarily detoxified via glutathione conjugation. In this study, it was hypothesized that molecules involved in the synthesis of glutathione would be diminished to replenish the glutathione depleted through conjugation reactions. Since S-adenosylmethionine (SAMe) is the primary source of the sulfur atom in glutathione, UPLC/MS and NMR were used to evaluate metabolites involved with the transulfuration pathway in urine samples collected during studies of eight liver toxic compounds in Sprague-Dawley rats. Urinary levels of creatine were increased on day 1 or day 2 in 8 high dose liver toxicity studies. Taurine concentration in urine was increased in only 3 of 8 liver toxicity studies while SAMe was found to be reduced in 4 of 5 liver toxicity studies. To further validate the results from the metabonomic studies, microarray data from rat liver samples following treatment with acetaminophen was obtained from the Gene Expression Omnibus (GEO) database. Some genes involved in the trans-sulfuration pathway, including guanidinoacetate N-methyltransferase, glycine N-methyltransferase, betaine-homocysteine methyltransferase and cysteine dioxygenase were found to be significantly decreased while methionine adenosyl transferase II, alpha increased at 24 h post-dosing, which is consistent with the SAMe and creatine findings. The metabolic and transcriptomic results show that the trans-sulfuration pathway from SAMe to glutathione was disturbed due to the administration of heptatotoxicants.

  10. Evaluations of the trans-sulfuration pathway in multiple liver toxicity studies.

    PubMed

    Schnackenberg, Laura K; Chen, Minjun; Sun, Jinchun; Holland, Ricky D; Dragan, Yvonne; Tong, Weida; Welsh, William; Beger, Richard D

    2009-02-15

    Drug-induced liver injury has been associated with the generation of reactive metabolites, which are primarily detoxified via glutathione conjugation. In this study, it was hypothesized that molecules involved in the synthesis of glutathione would be diminished to replenish the glutathione depleted through conjugation reactions. Since S-adenosylmethionine (SAMe) is the primary source of the sulfur atom in glutathione, UPLC/MS and NMR were used to evaluate metabolites involved with the transulfuration pathway in urine samples collected during studies of eight liver toxic compounds in Sprague-Dawley rats. Urinary levels of creatine were increased on day 1 or day 2 in 8 high dose liver toxicity studies. Taurine concentration in urine was increased in only 3 of 8 liver toxicity studies while SAMe was found to be reduced in 4 of 5 liver toxicity studies. To further validate the results from the metabonomic studies, microarray data from rat liver samples following treatment with acetaminophen was obtained from the Gene Expression Omnibus (GEO) database. Some genes involved in the trans-sulfuration pathway, including guanidinoacetate N-methyltransferase, glycine N-methyltransferase, betaine-homocysteine methyltransferase and cysteine dioxygenase were found to be significantly decreased while methionine adenosyl transferase II, alpha increased at 24 h post-dosing, which is consistent with the SAMe and creatine findings. The metabolic and transcriptomic results show that the trans-sulfuration pathway from SAMe to glutathione was disturbed due to the administration of heptatotoxicants.

  11. Evidence of magnetic isotope effects during thermochemical sulfate reduction

    PubMed Central

    Oduro, Harry; Harms, Brian; Sintim, Herman O.; Kaufman, Alan J.; Cody, George; Farquhar, James

    2011-01-01

    Thermochemical sulfate reduction experiments with simple amino acid and dilute concentrations of sulfate reveal significant degrees of mass-independent sulfur isotope fractionation. Enrichments of up to 13‰ for 33S are attributed to a magnetic isotope effect (MIE) associated with the formation of thiol-disulfide, ion-radical pairs. Observed 36S depletions in products are explained here by classical (mass-dependent) isotope effects and mixing processes. The experimental data contrasts strongly with multiple sulfur isotope trends in Archean samples, which exhibit significant 36S anomalies. These results support an origin other than thermochemical sulfate reduction for the mass-independent signals observed for early Earth samples. PMID:21997216

  12. Coupled pyrite concentration and sulfur isotopic insight into the paleo sulfate-methane transition zone (SMTZ) in the northern South China Sea

    NASA Astrophysics Data System (ADS)

    Lin, Qi; Wang, Jiasheng; Taladay, Katie; Lu, Hongfeng; Hu, Gaowei; Sun, Fei; Lin, Rongxiao

    2016-01-01

    The sulfate-methane transition zone (SMTZ) is an important diagenetic redox boundary within marine sediments where the anaerobic oxidation of methane (AOM), coupled with bacterial sulfate reduction, can promote sulfur isotopic enrichments in several solid phase minerals including pyrite (FeS2). Authigenic pyrite can form in concentrated abundances within the SMTZ and as such, can be used as a proxy to identify paleo-SMTZs. This study uses enrichments in 34S and anomalously high abundances of authigenic pyrites in 287 samples from the northern South China Sea (SCS) to determine the paleo-SMTZ. The pyrite samples were collected from sediment cores acquired at three sites, each of which are known to be located in natural gas hydrate-bearing regions. We assess the relative abundances of authigenic pyrites, the types of pyrite morphologies recovered in the cored sediments, and the sulfur isotopic values of recovered pyrite samples using two methods: (1) handpicked sample analysis using a binocular microscope, and (2) the chromium reduction method. Our results show that pyrite concentrations and sulfur isotopic compositions exhibit synchronous fluctuations, particularly from 6.8 m below seafloor (mbsf) to 8.4 mbsf at all three study sites. There is a significant increase in the occurrence of rod-like pyrite morphology within this key interval. We define the position of the paleo-SMTZ by the presence of anomalously high accumulations of pyrites at greater than 5.0 wt.% using the handpicking method or greater than 0.5 wt.% via the chromium reduction method, along with positive Δδ34S excursions greater than 10.0‰ VCDT. We discovered a regional paleo-SMTZ that is shallower than the modern SMTZ, suggesting a previous period of elevated methane flux from depth, possibly related to widespread gas hydrate dissociation.

  13. Trace and minor element variations and sulfur isotopes in crystalline and colloform ZnS: Incorporation mechanisms and implications for their genesis

    USGS Publications Warehouse

    Pfaff, Katharina; Koenig, Alan; Wenzel, Thomas; Ridley, Ian; Hildebrandt, Ludwig H.; Leach, David L.; Markl, Gregor

    2011-01-01

    Various models have been proposed to explain the formation mechanism of colloform sphalerite, but the origin is still under debate. In order to decipher influences on trace element incorporation and sulfur isotope composition, crystalline and colloform sphalerite from the carbonate-hosted Mississippi-Valley Type (MVT) deposit near Wiesloch, SW Germany, were investigated and compared to sphalerite samples from 52 hydrothermal vein-type deposits in the Schwarzwald ore district, SW Germany to study the influence of different host rocks, formation mechanisms and fluid origin on trace element incorporation. Trace and minor element incorporation in sphalerite shows some correlation to their host rock and/or origin of fluid, gangue, paragenetic minerals and precipitation mechanisms (e.g., diagenetic processes, fluid cooling or fluid mixing). Furthermore, crystalline sphalerite is generally enriched in elements like Cd, Cu, Sb and Ag compared to colloform sphalerite that mainly incorporates elements like As, Pb and Tl. In addition, sulfur isotopes are characterized by positive values for crystalline and strongly negative values for colloform sphalerite. The combination of trace element contents, typical minerals associated with colloform sphalerite from Wiesloch, sulfur isotopes and thermodynamic considerations helped to evaluate the involvement of sulfate-reducing bacteria in water-filled karst cavities. Sulfate-reducing bacteria cause a sulfide-rich environment that leads in case of a metal-rich fluid supply to a sudden oversaturation of the fluid with respect to galena, sphalerite and pyrite. This, however, exactly coincides with the observed crystallization sequence of samples involving colloform sphalerite from the Wiesloch MVT deposit.

  14. Evidence for a magmatic origin for Carlin-type gold deposits: isotopic composition of sulfur in the Betze-Post-Screamer Deposit, Nevada, USA

    NASA Astrophysics Data System (ADS)

    Kesler, Stephen E.; Riciputi, Lee C.; Ye, Zaojun

    2005-03-01

    We report here new sulfur isotope analyses from the Betze-Post-Screamer deposit, the largest Carlin-type gold deposit in the world. Carlin-type deposits contain high concentrations of arsenic, antimony, mercury, tellurium and other elements of environmental interest, and are surrounded by large volumes of crust in which these elements are also enriched. Uncertainty about the source of sulfur and metals in and around Carlin-type deposits has hampered formulation of models for their origin, which are needed for improved mineral exploration and environmental assessment. Previous studies have concluded that most Carlin-type deposits formed from sulfide sulfur that is largely of sedimentary origin. Most of these studies are based on analyses of mineral separates consisting of pre-ore diagenetic pyrite with thin overgrowths of ore-related arsenian pyrite rather than pure, ore-related pyrite. Our SIMS spot analyses of ore-related pyrite overgrowths in the Screamer zone of the Betze-Post-Screamer deposit yield δ34S values of about -1 to 4‰ with one value of about 7‰. Conventional analyses of realgar and orpiment separates from throughout the deposit yield δ34S values of about 5-7‰ with one value of 10‰ in the Screamer zone. These results, along with results from an earlier SIMS study in the Post zone of the deposit and phase equilibrium constraints, indicate that early arsenian pyrite were formed from fluids of magmatic origin with variable contamination from sulfur in Paleozoic sedimentary rocks. Later arsenic sulfides were formed from solutions to which sulfur of sedimentary origin had been added. The presence of Paleozoic sedimentary sulfur in Carlin-type deposits does not require direct involvement of hydrothermal solutions of sedimentary origin. Instead, it could have been added by magmatic assimilation of Paleozoic sedimentary rocks or by hydrothermal leaching of sulfur from wall rocks to the deposit. Thus, the dominant process delivering sulfur, arsenic

  15. Sulfur isotope mass-independent fractionation in impact deposits of the 3.2 billion-year-old Mapepe Formation, Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    van Zuilen, M. A.; Philippot, P.; Whitehouse, M. J.; Lepland, A.

    2014-10-01

    Theoretical and experimental studies have shown that atmospheric SO2 isotopologue self-shielding effects in the 190-220 nm region of the solar spectrum are the likely cause for mass independent fractionation of sulfur isotopes (S-MIF). The main products of this photochemical reaction - SO3 and S0 - typically define a compositional array of ca. Δ33S/δ34S = 0.06-0.14. This is at odds with the generally observed trend in Archean sulfides, which broadly defines an array of ca. Δ33S/δ34S = 0.9. Various explanations have been proposed, including a diminution of δ34S caused by chemical and biogenic mass-dependent fractionation of sulfur isotopes (S-MDF), mixing with photolytic products produced during felsic volcanic events, or partial blocking of the low-wavelength part of the spectrum due to the presence of reduced atmospheric gases or an organic haze. Early in Earth history large meteorite impacts would have ejected dust and gas clouds into the atmosphere that shielded solar radiation and affected global climate. It is thus likely that at certain time intervals of high meteorite flux the atmosphere was significantly perturbed, having an effect on atmospheric photochemistry and possibly leaving anomalous sulfur isotopic signatures in the rock record. Here we describe the sulfur isotopic signatures in sulfides of spherule beds S2, S3 and S4 of the Barberton Greenstone Belt, South Africa. In particular, in spherule bed S3 - and to a lesser extent S4 - a trend of ca. Δ33S/δ34S = 0.23 is observed that closely follows the expected trend for SO2-photolysis in the 190-220 nm spectral range. This suggests that an impact dust cloud (deposited as spherule beds), which sampled the higher region of the atmosphere, specifically incorporated products of SO2 photolysis in the 190-220 nm range, and blocked photochemical reactions at higher wavelengths (250-330 nm band). By implication, the generally observed Archean trend appears to be the result of mixing of different MIF

  16. Stable sulfur isotope ratios and water-soluble inorganic compositions of PM10 in Yichang City, central China.

    PubMed

    Yang, Zhou; Li, Xiao-Dong; Deng, Jie; Wang, Hai-Yun

    2015-09-01

    Chemical and sulfate-sulfur isotopic compositions of water-soluble inorganic ions were analyzed for aerosol sample particulate matter with aerodynamic diameter ≤10 μm (PM10) collected during 17-28 December 2012 at Yichang City, Hubei Province, central China. Most water-soluble inorganic ions, except for NO3 (-) and NH4 (+), showed slightly higher concentration in daytime than in nighttime, and the major detected ions followed the order of SO4 (2-) > NO3 (-) > Ca(2+) > Na(+) > NH4 (+) > Cl(-) in daytime and nighttime, of which SO4 (2-) is the most abundant ionic component that accounted for about 49.1 and 49.3 % of the total mass of analyzed ions in daytime and nighttime, respectively. According to the correlation coefficients among the mass concentrations of water-soluble inorganic ions, there may mainly exist in forms of (NH4)2SO4 and NH4NO3 in daytime and NH4NO3 in nighttime. The δ(34)S values of sulfate ranged from +2.82 to +4.63 ‰ (average +3.97 ‰) in daytime and from +2.90 to +5.39 ‰ (average +4.08 ‰) in nighttime, indicating that the source of sulfate in PM10 was mainly derived from coal burning (δ(34)S, +3.68 ‰) in Yichang City. The [NO3 (-)]/[SO4 (2-)] mass ratio varied between 0.2 and 0.6 with an average of 0.4 in daytime and 0.1 to 0.8 with an average of 0.4 in nighttime, which implying that the stationary source emissions would be more important than the vehicle emissions in the studied area. As a whole, the mixture of coal burning, vehicle exhaust, and resuspended road dust would be responsible for the sources of PM10 in Yichang City during wintertime. PMID:25960017

  17. Native sulfur, sulfates and sulfides from the active Campi Flegrei volcano (southern Italy): Genetic environments and degassing dynamics revealed by mineralogy and isotope geochemistry

    NASA Astrophysics Data System (ADS)

    Piochi, Monica; Mormone, Angela; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe

    2015-10-01

    We investigated sulfur-bearing minerals from the Campi Flegrei caldera, southern Italy, in relation to the increase of hydrothermal activity phenomena since 2006, aimed at providing insights into the volcanic system dynamics. Mineral encrustations and muds were sampled between 2013 and 2015 at the long-standing degassing crater of the Solfatara tuff cone and its recently restless north-eastern Pisciarelli slope. Deep-seated sulfides were further separated from two drill cores (AGIP's Mofete boreholes: 1500 m and 2695 m depth). The mineral assemblage and texture of sampled encrustations were determined by X-ray diffraction, optical and scanning electron microscopy and X-ray microanalysis by energy dispersive spectrometry. Native sulfur and alunite dominate among the newly formed mineral phases. Other minerals are mostly alunogen, and locally pickeringite, potassium alum, hematite and pyrite. Mereiterite and amarillite sporadically occur. The mud pools are rich in gypsum, potassium alum and pyrite. Quartz and argillic phases, locally with analcime, are dispersed in the outcropping rocks. δ34S values were determined for shallow subsurface native sulfur (- 5.5 to 0.0‰) and alunite (- 1.7 to - 0.2‰), as well as for the deep-seated pyrite (3.3 to 7.4‰ in the depth range:1500-2695 m). δ18O values were measured for shallow native alunite (4.2 to 7.0‰). Pisciarelli alunite was finally analyzed for its 87Sr/86Sr ratio and 143Nd/144Nd ratios (0.707517 ± 6 and 0.512459 ± 6, respectively). Textural and isotopic data constrain the genesis of alunite at the expense of K-feldspars through rock alteration by hydrothermal fluids. We suggest that the caldera is a low-sulfidation system hosting acid-sulfate deposits in its active degassing area. The acid-sulfate environment developed on an argillitic facies that thins outwards and is characteristic for steam-heated and magmatic-steam environments. These environments developed in relation to the fractured settings that

  18. Source Of Hydrogen Sulfide To Sulfidic Spring And Watershed Ecosystems In Northern Sierra De Chiapas, Mexico Based On Sulfur And Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Rosales Lagarde, L.; Boston, P. J.; Campbell, A.

    2013-12-01

    At least four watersheds in northern Sierra de Chiapas, Mexico are fed by conspicuous karst sulfide-rich springs. The toxic hydrogen sulfide (H2S) in these springs nurtures rich ecosystems including especially adapted microorganisms, invertebrates and fish. Sulfur and carbon isotopic analysis of various chemical species in the spring water are integrated within their hydrogeologic context to evaluate the hydrogen sulfide source. Constraining the H2S origin can also increase the understanding of this compound effect in the quality of the nearby hydrocarbon reservoirs, and the extent to which its oxidation to sulfuric acid increases carbonate dissolution and steel corrosion in surface structures. The SO42-/H2S ratio in the spring water varies from 70,000 to 2 meq/L thus sulfate is the dominant species in the groundwater system. This sulfate is mainly produced from anhydrite dissolution based on its isotopic signature. The Δ SO42--H2S range of 16 spring water samples (30-50 ‰) is similar to the values determined by Goldhaber & Kaplan (1975) and Canfield (2001) for low rates of bacterial sulfate reduction suggesting that this is the most important mechanism producing H2S. Although the carbon isotopes do not constrain the nature of the organic matter participating in this reaction, this material likely comes from depth, perhaps as hydrocarbons, due to the apparent stability of the system. The organic matter availability and reactivity probably control the progress of sulfate reduction. The subsurface environments identified in the area also have different sulfur isotopic values. The heavier residual sulfate isotopic value in the Northern brackish springs (δ34S SO42- ≥ 18 ‰) compared to the Southern springs (δ34S SO42- ~18 ‰) suggests sulfate reduction is particularly enhanced in the former, probably by contribution of organic matter associated with oil produced water. In comparison, the composition of the Southern aquifer is mainly influenced by halite

  19. The Effect of Temperature and Hydrogen Limited Growth on the Fractionation of Sulfur Isotopes by Thermodesulfatator indicus, a Deep-sea Hydrothermal Vent Sulfate-Reducing Bacterium

    NASA Astrophysics Data System (ADS)

    Hoek, J.; Reysenbach, A.; Habicht, K.; Canfield, D. E.

    2004-12-01

    Sulfate-reducing bacteria fractionate sulfur isotopes during dissimilatory sulfate reduction, producing sulfide depleted in 34S. Although isotope fractionation during sulfate reduction of pure cultures has been extensively studied, most of the research to date has focused on mesophilic sulfate reducers, particularly for the species Desulfovibrio desulfuricans. Results from these studies show that: 1) fractionations range from 3-46‰ with an average around 18‰ , 2) when organic electron donors are utilized, the extent of fractionation is dependent on the rate of sulfate reduction, with decreasing fractionations observed with higher specific rates, 3) fractionations are suppressed with low sulfate concentrations, and when hydrogen is used as the electron donor. High specific sulfate-reduction rates are encountered when sulfate-reducing bacteria metabolize at their optimal temperature and under non-limiting substrate conditions. Changes in both temperature and substrate availability could shift fractionations from those expressed under optimal growth conditions. Sulfate reducers may frequently experience substrate limitation and sub-optimal growth temperatures in the environment. Therefore it is important to understand how sulfate-reducing bacteria fractionate sulfur isotopes under conditions that more closely resemble the restrictions imposed by the environment. In this study the fractionation of sulfur isotopes by Thermodesulfatator indicus was explored during sulfate reduction under a wide range of temperatures and with both hydrogen-saturating and hydrogen-limited conditions. T. indicus is a thermophilic (temperature optimum = 70° C) chemolithotrophic sulfate-reducing bacterium, which was recently isolated from a deep-sea hydrothermal vent on the Central Indian Ridge. This bacterium represents the type species of a new genus and to date is the most deeply branching sulfate-reducing bacterium known. T. indicus was grown in carbonate-buffered salt-water medium

  20. Assessment of marine-derived nutrients in the Copper River Delta, Alaska, using natural abundance of the stable isotopes of nitrogen, sulfur, and carbon

    USGS Publications Warehouse

    Kline, Thomas C.; Woody, Carol Ann; Bishop, Mary Anne; Powers, Sean P.; Knudsen, E. Eric

    2007-01-01

    We performed nitrogen, sulfur, and carbon stable isotope analysis (SIA) on maturing and juvenile anadromous sockeye and coho salmon, and periphyton in two Copper River delta watersheds of Alaska to trace salmonderived nutrients during 2003–2004. Maturing salmon were isotopically enriched relative to alternate freshwater N, S, and C sources as expected, with differences consistent with species trophic level differences, and minor system, sex, and year-to-year differences, enabling use of SIA to trace these salmon-derived nutrients. Periphyton naturally colonized, incubated, and collected using Wildco Periphtyon Samplers in and near spawning sites was 34S- and 15N-enriched, as expected, and at all freshwater sites was 13C-depleted. At nonspawning and coho-only sites, periphyton 34S and 15N was generally low. However, 34S was low enough at some sites to be suggestive of sulfate reduction, complicating the use of S isotopes. Juvenile salmon SIA ranged in values consistent with using production derived from re-mineralization as well as direct utilization, but only by a minority fraction of coho salmon. Dependency on salmon-derived nutrients ranged from relatively high to relatively low, suggesting a space-limited system. No one particular isotope was found to be superior for determining the relative importance of salmon-derived nutrients.

  1. Effect of hydrogen limitation and temperature on the fractionation of sulfur isotopes by a deep-sea hydrothermal vent sulfate-reducing bacterium

    NASA Astrophysics Data System (ADS)

    Hoek, Joost; Reysenbach, Anna-Louise; Habicht, Kirsten S.; Canfield, Donald E.

    2006-12-01

    The fractionation of sulfur isotopes by the thermophilic chemolithoautotrophic Thermodesulfatator indicus was explored during sulfate reduction under excess and reduced hydrogen supply, and the full temperature range of growth (40-80 °C). Fractionation of sulfur isotopes measured under reduced H 2 conditions in a fed-batch culture revealed high fractionations (24-37‰) compared to fractionations produced under excess H 2 supply (1-6‰). Higher fractionations correlated with lower sulfate reduction rates. Such high fractionations have never been reported for growth on H 2. For temperature-dependant fractionation experiments cell-specific rates of sulfate reduction increased with increasing temperatures to 70 °C after which sulfate-reduction rates rapidly decreased. Fractionations were relatively high at 40 °C and decreased with increasing temperature from 40-60 °C. Above 60 °C, fractionation trends switched and increased again with increasing temperatures. These temperature-dependant fractionation trends have not previously been reported for growth on H 2 and are not predicted by a generally accepted fractionation model for sulfate reduction, where fractionations are controlled as a function of temperature, by the balance of the exchange of sulfate across the cell membrane, and enzymatic reduction rates of sulfate. Our results are reproduced with a model where fractionation is controlled by differences in the temperature response of enzyme reaction rates and the exchange of sulfate in and out of the cell.

  2. Involvement of magmatic fluids at the Laloki and Federal Flag massive sulfide Cu-Zn-Au-Ag deposits, Astrolabe mineral district, Papua New Guinea: sulfur isotope evidence

    NASA Astrophysics Data System (ADS)

    Noku, Shadrach K.; Espi, Joseph O.; Matsueda, Hiroharu

    2015-01-01

    We present the first sulfur (S) isotope data of sulfides, sulfates, pyrite in host mudstone, and bulk sulfur of gabbroic rocks from the Laloki and Federal Flag massive Cu-Zn-Au-Ag deposits in the Astrolabe mineral district, Papua New Guinea. Early-stage pyrite-marcasite, chalcopyrite, and sphalerite from Laloki display wide range of δ34S values from -4.5 to +7.0 ‰ ( n = 16). Late-stage pyrite, chalcopyrite, and sphalerite have restricted δ34S values of -1.9 to +4.7 ‰ ( n = 16). The mineralizing stage these correspond to had moderately saline (5.9-8.4 NaCl eq. wt%) mineralizing fluids of possible magmatic origin. A single analysis of late-stage barite has a value of δ34S +17.9 ‰, which is likely similar to coexisting seawater sulfate. Pyrite from the foot-wall mudstone at Laloki has very light δ34S values of -36.1 to -33.8 ‰ ( n = 2), which suggest an organic source for S. Pyrite-marcasite and chalcopyrite from Federal Flag show δ34S values of -2.4 to -1.9 ‰ ( n = 2), consistent with a magmatic origin, either leached from intrusive magmatic rocks or derived from magmatic-hydrothermal fluids. The very narrow range and near-zero δ34S values (-1.0 to +0.6 ‰) of bulk gabbroic samples is consistent with mantle-derived magmatic S. Sulfur isotope characteristics of sulfides and sulfates are, however, very similar to base metal sulfide accumulations associated with modern volcanic arcs and sedimented mid-ocean ridges. The most reasonable interpretation is that the range of the sulfide and sulfate δ34S values from both Laloki and Federal Flag massive sulfide deposits is indicative of the complex interaction of magmatic fluids, seawater, gabbroic rocks, and mudstone.

  3. Mineralogical and sulfur isotopic characterization of the sulfur-bearing mineralization from the active degassing area of Campi Flegrei caldera (southern Italy)

    NASA Astrophysics Data System (ADS)

    Mormone, Angela; Piochi, Monica; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe

    2015-04-01

    The Campi Flegrei caldera is a site of persistent hydrothermal circulation and gaseous emissions inside the Pozzuoli town and nearby the city of Napoli (Italy). The solfataric phenomena are associated with episodes of low-magnitude seismicity and vertical ground displacement since Roman times, evolving to the Monte Nuovo eruption in the 1538 AD. Pronounced geochemical anomalies, uplift rates up to 1 m/y and up to ten thousands microearthquakes per year also characterized the four most recent decades of unrest. The degassing phenomena are concentrated within the Solfatara crater, although, since 2006, the hydrothermal activity strongly increased in the Pisciarelli district, i.e. on the north-east slope of the tuff. We investigated sulfur-bearing mineral precipitates sampled from the active fumaroles both within the Solfatara and along the Pisciarelli slope. Mineral assemblage, texture and chemistry were determined for the efflorescence precipitated nearby the fumaroles and along the mud pool by x-ray diffraction, back-scattered electron microscope and electron diffuse microanalysis. δ34S compositions were also determined on separated sulfur-minerals. The new data have been compared with scattered literature data, including few existing for the previous '70 and '80 unrest episodes. Native sulfur and alunite are the main mineral phases that associate with alunogene, and, locally, pickeringite and potassium alum. Sporadically mereiterite, amarillite, and pyrite have been found as neogenesis mineralization along the outcropping rocks. The mud pool is rich in gypsum, potassium alum and pyrite. δ34S values range from -5.48 to 0.0‰, being slightly lower than previous data. The obtained results suggest that the Pisciarelli area is characterized by magmatic-hydrothermal, magmatic-steam and steam-heated environments, developed on a argillitic hydrothermal facies that thickens in correspondence of the degassing area. These environments develop and continuously evolve in

  4. What Does the Absence of Mass-independent Fractionation of Sulfur Isotopes at 2.8-3.2 Ga say About the Early Atmosphere?

    NASA Astrophysics Data System (ADS)

    Goldman, S. D.; Kasting, J. F.

    2005-12-01

    The presence of mass-independent fractionation (MIF) of sulfur isotopes in Archean sedimentary provides evidence for a low-O2 atmosphere prior to 2.4 Ga (1). Recent data hints at the possibility that S-MIF vanished transiently some time between 3.4 and 2.7 Ga (2). The absence of S-MIF after 2.4 Ga is commonly attributed to the rise of O2 in the atmosphere, since the presence of free O2 would have oxidized all sulfur before removal from the atmosphere, thereby erasing any MIF that had existed between reservoirs (3). However, if free O2 did not appear in the atmosphere until 2.4 Ga, then why did S-MIF disappear for hundreds of millions of year prior to 2.7 Ga? Could S-MIF have been eliminated from the rock record without the presence of free O2 in the atmosphere? Two different mechanisms will be discussed. The first possibility is that H2 levels decreased sufficiently to oxidize all MIF, but were still high enough to prevent free O2 from building up to appreciable levels in the atmosphere. Stabilization of H2 at these intermediate levels could have been triggered by a number of mechanisms controlling the H2 budget, the most promising of which is changes in the biogeochemical processing of sulfur itself (4). Before the advent of bacterial sulfate reduction (BSR), seawater sulfate would have reacted with Fe in basalts, removing sulfur from the surface in oxidized form. As removing sulfur from the surface as sulfate requires oxidation of SO2, this implies that H2 must have been generated by the geochemical S cycle. After the advent of BSR sulfur would be buried in reduced form as pyrite. Burial of sulfur as pyrite would require reduction of SO2, thus the biogeochemical S cycle would have consumed H2. This change in S cycling likely would have impacted the H2 budget more than any other change in element cycling, other than direct changes in the H2 fluxes into and out of the system. The second possibility is that the atmosphere was reduced with respect to the sulfur

  5. Multiple stable isotope characterization as a forensic tool to distinguish acid scavenger samples

    SciTech Connect

    Moran, James J.; Kreuzer, Helen W.; Carman, April J.; Wahl, Jon H.; Duckworth, Douglas C.

    2012-01-01

    Acid scavengers are frequently used as stabilizer compounds in a variety of applications. When used to stabilize volatile compounds such as nerve agents, the lower volatility and higher stability of acid scavengers make them more persistent in a post-event forensic setting. We are employing compound-specific stable isotope analysis of the carbon, nitrogen, and hydrogen components of three acid scavenging compounds (N,N-diethylaniline, tributylamine, and triethylamine) as a tool for distinguishing between different samples of the stabilizers. Combined analysis of three stable isotopes in these samples improves the technique’s resolving potential, enhancing sample matching capabilities. The compound specific methods developed here can be applied to instances where these compounds are not pure, such as when mixed with an agent or when found as a residue at an event site. Effective sample matching can be crucial for linking compounds at multiple event sites or linking a supply inventory to an event.

  6. Carbon and nitrogen stable isotopes in coastal benthic populations under multiple organic enrichment sources.

    PubMed

    Sampaio, Leandro; Rodrigues, Ana Maria; Quintino, Victor

    2010-10-01

    In a dispersive coastal area under multiple organic enrichment sources, stable isotopes were used to trace organic sources of carbon and nitrogen in sediments and benthic macrofauna. The Bivalve Abra alba and the Polychaetes Nephtys sp. and Pectinaria (Lagis) koreni were reliable indicators of the input of terrestrial-derived organic matter into this coastal area, either originated in outfall sewage discharges or estuarine outflow. An isotopic depletion was observed up to 250 m from the outfall branches, much stronger in the biota than in the sediments. An enrichment of 2 ‰ in the sediments, and 2-6 ‰ in the species was noticed in sites located farther than 1500 m from the outfall. Depositivores and carnivores/omnivores gave the best picture of the extension of the sewage dispersion and incorporation into the food web.

  7. Sulfur isotope and trace element systematics of zoned pyrite crystals from the El Indio Au-Cu-Ag deposit, Chile

    NASA Astrophysics Data System (ADS)

    Tanner, Dominique; Henley, Richard W.; Mavrogenes, John A.; Holden, Peter

    2016-04-01

    We present a comparative study between early, massive pyrite preceding (Cu-Ag) sulfosalt mineralization in high-temperature feeder zones (`early pyrite') and late pyrite that formed during silicic alteration associated with Au deposition (`late pyrite') at the El Indio high-sulfidation Au-Ag-Cu deposit, Chile. We use coupled in situ sulfur isotope and trace element analyses to chronologically assess geochemical variations across growth zones in these pyrite crystals. Early pyrite that formed in high-temperature feeder zones shows intricate oscillatory zonation of Cu, with individual laminae containing up to 1.15 wt% Cu and trace Co, As, Bi, Ni, Zn, Se, Ag, Sb, Te, Au, Pb and Bi. Late pyrite formed after (Cu-Ag) sulfosalt mineralization. It contains up to 1.14 wt% As with trace Cu, Zn, Pb, V, Mn, Co, Ni, Ge, Se, Ag, Sb, Te, Pb and Bi, as well as colloform Cu-rich growth bands containing vugs toward the outer edges of some crystals. Plotting the trace element data in chronological order (i.e., from core to rim) revealed that Co and Ni were the only elements to consistently co-vary across growth zones. Other trace elements were coupled in specific growth zones, but did not consistently co-vary across any individual crystal. The δ34S of early pyrite crystals in high-temperature feeder zones range from -3.19 to 1.88 ‰ (±0.5 ‰), consistent with sublimation directly from a high-temperature magmatic vapor phase. Late pyrite crystals are distinctly more enriched in δ34S than early pyrite (δ34S = 0.05-4.77 ‰, ±0.5 ‰), as a consequence of deposition from a liquid phase at lower temperatures. It is unclear whether the late pyrite was deposited from a small volume of liquid condensate, or a larger volume of hydrothermal fluid. Both types of pyrite exhibit intracrystalline δ34S variation, with a range of up to 3.31 ‰ recorded in an early pyrite crystal and up to 4.48 ‰ in a late pyrite crystal. Variations in δ34Spyrite at El Indio did not correspond with

  8. Multiple water isotope proxy reconstruction of extremely low last glacial temperatures in Eastern Beringia (Western Arctic)

    NASA Astrophysics Data System (ADS)

    Porter, Trevor J.; Froese, Duane G.; Feakins, Sarah J.; Bindeman, Ilya N.; Mahony, Matthew E.; Pautler, Brent G.; Reichart, Gert-Jan; Sanborn, Paul T.; Simpson, Myrna J.; Weijers, Johan W. H.

    2016-04-01

    Precipitation isotopes are commonly used for paleothermometry in high latitude regions. Here we present multiple water isotope