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Artykuły w czasopismach na temat "Hydrogen isotopic composition"
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Hürkamp, Kerstin, Nadine Zentner, Anne Reckerth, Stefan Weishaupt, Karl-Friedrich Wetzel, Jochen Tschiersch i Christine Stumpp. "Spatial and Temporal Variability of Snow Isotopic Composition on Mt. Zugspitze, Bavarian Alps, Germany". Journal of Hydrology and Hydromechanics 67, nr 1 (1.03.2019): 49–58. http://dx.doi.org/10.2478/johh-2018-0019.
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Abstract High amounts of precipitation are temporarily stored in high-alpine snow covers and play an important role for the hydrological balance. Stable isotopes of hydrogen (δ2H) and oxygen (δ18O) in water samples have been proven to be useful for tracing transport processes in snow and meltwater since their isotopic ratio alters due to fractionation. In 18 snow profiles of two snowfall seasons, the temporal and spatial variation of isotopic composition was analysed on Mt. Zugspitze. The δ18O and δ2H ranged between -26.7‰ to -9.3‰ and -193.4‰ to -62.5‰ in 2014/2015 and between -26.5‰ to -10.5‰ and -205.0‰ to -68.0‰ in 2015/2016, respectively. Depth-integrated samples of entire 10 cm layers and point measurements in the same layers showed comparable isotopic compositions. Isotopic composition of the snowpack at the same sampling time in spatially distributed snow profiles was isotopically more similar than that analysed at the same place at different times. Melting and refreezing were clearly identified as processes causing isotope fractionation in surficial, initial base or refrozen snow layers. For the future, a higher sampling frequency with detailed isotopic composition measurements during melt periods are recommended to improve the understanding of mass transport associated with snowmelt.
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Uemura, Ryu, Yudai Kina, Chuan-Chou Shen i Kanako Omine. "Experimental evaluation of oxygen isotopic exchange between inclusion water and host calcite in speleothems". Climate of the Past 16, nr 1 (7.01.2020): 17–27. http://dx.doi.org/10.5194/cp-16-17-2020.
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Abstract. The oxygen and hydrogen isotopic compositions of water in fluid inclusions in speleothems are important hydroclimate proxies because they provide information on the isotopic compositions of rainwater in the past. Moreover, because isotopic differences between fluid inclusion water and the host calcite provide information on the past isotopic fractionation factor, they are also useful for quantitative estimation of past temperature changes. The oxygen isotope ratio of inclusion water (δ18Ofi), however, may be affected by isotopic exchange between the water and the host carbonate. Thus, it is necessary to estimate the bias caused by this postdepositional effect for precise reconstruction of paleotemperatures. Here, we evaluate the isotopic exchange reaction between inclusion water and host calcite based on a laboratory experiment involving a natural stalagmite. Multiple stalagmite samples cut from the same depth interval were heated at 105 ∘C in the laboratory from 0 to 80 h. Then, the isotopic compositions of the inclusion water were measured. In the 105 ∘C heating experiments, the δ18Ofi values increased from the initial value by 0.7 ‰ and then remained stable after ca. 20 h. The hydrogen isotope ratio of water showed no trend in response to the heating experiments, suggesting that the hydrogen isotopic composition of fluid inclusion water effectively reflects the composition of past drip water. We then evaluated the process behind the observed isotopic variations using a partial equilibration model. The experimental results are best explained by the assumption that a thin CaCO3 layer surrounding the inclusion reacted with the water. The amount of CaCO3 that reacted with the water is equivalent to 2 % of the water inclusions in molar terms. These results suggest that the magnitude of the isotopic exchange effect has a minor influence on paleotemperature estimates for Quaternary climate reconstructions.
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Kennedy, Brenda V., i H. Roy Krouse. "Isotope fractionation by plants and animals: implications for nutrition research". Canadian Journal of Physiology and Pharmacology 68, nr 7 (1.07.1990): 960–72. http://dx.doi.org/10.1139/y90-146.
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The isotopic compositions of animal tissues, minerals, and fluids reflect those of ingested food and water and inhaled gases. This relationship is illustrated by a review of data pertaining to five light elements of biological interest (carbon, nitrogen, hydrogen, oxygen, and sulphur). Processes affecting the isotopic composition of inorganic compounds in reservoirs are summarized, and isotope fractionation during transfer of elements from these inorganic reservoirs through progressive trophic levels of food webs is discussed. Variability of δ values within and among individuals, populations, and species of plants and animals is attributed to at least six factors: locality, dietary selectivity, biochemical composition of food, isotope effects in metabolic processes, turnover rates, and stress. Features of a variety of terrestrial and aquatic ecosystems are used to illustrate basic concepts. Future research should seek to clarify specific mechanisms affecting δ values during the transfer of elements through food webs.Key words: food webs, stable isotopes, isotope fractionation, ecosystems.
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Qu, Simin, Xueqiu Chen, Yifan Wang, Peng Shi, Shuai Shan, Jianfeng Gou i Peng Jiang. "Isotopic Characteristics of Precipitation and Origin of Moisture Sources in Hemuqiao Catchment, a Small Watershed in the Lower Reach of Yangtze River". Water 10, nr 9 (31.08.2018): 1170. http://dx.doi.org/10.3390/w10091170.
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The stable isotopes of oxygen and hydrogen in the water cycle have become a significant tool to study run-off formation, hydrograph separation, and the origin of precipitation. Precipitation assessment based on isotopic data has a potential implication for moisture sources. In the study, δD and δ18O of precipitation samples collected from six rainfall events were analyzed for stable isotope composition to provide implication of isotopic characteristics as well as moisture sources in Hemuqiao basin within Lake Tai drainage basin, eastern China. In these events, stable oxygen and hydrogen isotopic composition of precipitation had strong variations. Models of the meteoric water line and deuterium excess for different rainfall types (typhoon and plum rain, which is caused by precipitation along a persistent stationary front known as the Meiyu front for nearly two months during the late spring and early summer between eastern Russia, China, Taiwan, Korea and Japan) were established. Compared with plum rain, the moisture source of typhoon events had higher relative humidity and temperature. Moisture transport pathways were traced using the Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT Model, developed by NOAA, Washington DC, U.S.) to verify the linkage with isotopic composition and moisture source. The moisture sources of typhoon events mostly derived from tropical ocean air with higher isotopic value, while that of plum rain events came from near-source local air with lower isotopic value.
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Pieterse, G., M. C. Krol, A. M. Batenburg, L. P. Steele, P. B. Krummel, R. L. Langenfelds i T. Röckmann. "Global modelling of H<sub>2</sub> mixing ratios and isotopic compositions with the TM5 model". Atmospheric Chemistry and Physics Discussions 11, nr 2 (17.02.2011): 5811–66. http://dx.doi.org/10.5194/acpd-11-5811-2011.
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Abstract. The isotopic composition of molecular hydrogen (H2) contains independent information for constraining the global H2 budget. To explore this, we have implemented hydrogen sources and sinks, including their isotopic composition, into the global chemistry transport model TM5. For the first time, a global model now includes a simplified but explicit isotope reaction scheme for the photochemical production of H2. We present a comparison of modelled results for the H2 mixing ratio and isotope composition with available measurements on the seasonal to inter annual time scales for the years 2001–2007. The base model results agree well with observations for H2 mixing ratios. For δD[H2], modelled values are slightly lower than measurements. A detailed sensitivity study is performed to identify the most important parameters for modelling the isotopic composition of H2. The results show that on the global scale, the discrepancy between model and measurements can be closed by adjusting the default values of the isotope effects in deposition, photochemistry and the stratosphere-troposphere exchange within the known range of uncertainty. However, the available isotope data do not provide sufficient information to uniquely constrain the global isotope budget. Therefore, additional studies focussing on the isotopic composition near the tropopause and on the isotope effects in the photochemistry and deposition are recommended.
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Hamzić Gregorčič, Staša, Doris Potočnik, Federica Camin i Nives Ogrinc. "Milk Authentication: Stable Isotope Composition of Hydrogen and Oxygen in Milks and Their Constituents". Molecules 25, nr 17 (2.09.2020): 4000. http://dx.doi.org/10.3390/molecules25174000.
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This paper summarises the isotopic characteristics, i.e., oxygen and hydrogen isotopes, of Slovenian milk and its major constituents: water, casein, and lactose. In parallel, the stable oxygen isotope ratios of cow, sheep, and goat’s milk were compared. Oxygen stable isotope ratios in milk water show seasonal variability and are also 18O enriched in relation to animal drinking water. The δ18Owater values were higher in sheep and goat’s milk when compared to cow milk, reflecting the isotopic composition of drinking water source and the effect of differences in the animal’s thermoregulatory physiologies. The relationship between δ18Omilk and δ18Olactose is an indication that even at lower amounts (>7%) of added water to milk can be determined. This procedure once validated on an international scale could become a reference method for the determination of milk adulteration with water.
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Li, Xiangnan, Baisha Weng, Denghua Yan, Tianling Qin, Kun Wang, Wuxia Bi, Zhilei Yu i Batsuren Dorjsuren. "Anthropogenic Effects on Hydrogen and Oxygen Isotopes of River Water in Cities". International Journal of Environmental Research and Public Health 16, nr 22 (12.11.2019): 4429. http://dx.doi.org/10.3390/ijerph16224429.
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Stable hydrogen and oxygen isotopes are important indicators for studying water cycles. The isotopes are not only affected by climate, but are also disturbed by human activities. Urban construction has changed the natural attributes and underlying surface characteristics of river basins, thus affecting the isotopic composition of river water. We collected urban river water isotope data from the Global Network for Isotopes in Rivers (GNIR) database and the literature, and collected river water samples from the Naqu basin and Huangshui River basin on the Tibetan Plateau to measure hydrogen and oxygen isotopes. Based on 13 pairs of urban area and non-urban area water samples from these data, the relationship between the isotopic values of river water and the artificial surface area of cities around rivers was analyzed. The results have shown that the hydrogen and oxygen isotope (δD and δ18O) values of river water in urban areas were significantly higher than those in non-urban areas. The isotopic variability of urban and non-urban water was positively correlated with the artificial surface area around the rivers. In addition, based on the analysis of isotope data from 21 rivers, we found that the cumulative effects of cities on hydrogen and oxygen isotopes have led to differences in surface water line equations for cities with different levels of development. The combined effects of climate and human factors were the important reasons for the variation of isotope characteristics in river water in cities. Stable isotopes can not only be used to study the effects of climate on water cycles, but also serve as an important indicator for studying the degree of river development and utilization.
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Abiye, Tamiru A., Molla B. Demlie i Haile Mengistu. "An Overview of Aquifer Physiognomies and the δ18O and δ2H Distribution in the South African Groundwaters". Hydrology 8, nr 2 (19.04.2021): 68. http://dx.doi.org/10.3390/hydrology8020068.
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A comprehensive assessment of the stable isotope distribution in the groundwater systems of South Africa was conducted in relation to the diversity in the aquifer lithology and corresponding hydraulic characteristics. The stable isotopes of oxygen (18O) and hydrogen (2H) in groundwater show distinct spatial variation owing to the recharge source and possibly mixing effect in the aquifers with the existing water, where aquifers are characterized by diverse hydraulic conductivity and transmissivity values. When the shallow aquifer that receives direct recharge from rainfall shows a similar isotopic signature, it implies less mixing effect, while in the case of deep groundwater interaction between recharging water and the resident water intensifies, which could change the isotope signature. As aquifer depth increases the effect of mixing tends to be minimal. In most cases, the isotopic composition of recharging water shows depletion in the interior areas and western arid zones which is attributed to the depleted isotopic composition of the moisture source. The variations in the stable isotope composition of groundwater in the region are primarily controlled by the isotope composition of the rainfall, which shows variable isotope composition as it was observed from the local meteoric water lines, in addition to the evaporation, recharge and mixing effects.
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Kakareka, S. V., T. I. Kukharchyk, A. A. Ekaykin i Yu G. Giginyak. "Stable isotopes in the snow of the coastal areas of Antarctica". Doklady of the National Academy of Sciences of Belarus 65, nr 4 (2.09.2021): 495–502. http://dx.doi.org/10.29235/1561-8323-2021-65-4-495-502.
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The first results of study of stable isotopes of oxygen (δ18O) and hydrogen (δD) in the snow samples taken on the islands of Marguerite Bay (Antarctic Peninsula), in the Vecherny Oasis (Enderby Land), and Larsemann Hills (Princess Elizabeth Land) by the participants of the 12th Belarusian Antarctic Expedition (January–March 2020) are presented. The concentration of water isotopes: deuterium (D) and oxygen-18 (18O) in the samples was determined using a laser isotope composition analyzer Picarro L2130. A total of 32 snow samples were analyzed. The statistical parameters of the isotopic composition of snow were estimated, and the main differences in the content of δ18O and δD between the study areas were shown. A decrease in the content of heavy oxygen and hydrogen isotopes in the newly fallen snow to the old snow of the surface horizons is shown. The maximum values of δ18O and δD are typical for the Maritime Antarctica, decreasing towards the coastal zone and further – towards its continental part. The possible factors affecting the isotope content are described. It is shown that the monitoring of the isotope composition can be an integral part of the monitoring of climatic changes within the area of operation of the Belarusian Antarctic Expedition. The study of the isotopic composition of surface snow is important for the reconstruction of the paleoclimate of the marginal zone of the Antarctic ice sheet based on the ice cores study.
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Pieterse, G., M. C. Krol, A. M. Batenburg, L. P. Steele, P. B. Krummel, R. L. Langenfelds i T. Röckmann. "Global modelling of H<sub>2</sub> mixing ratios and isotopic compositions with the TM5 model". Atmospheric Chemistry and Physics 11, nr 14 (20.07.2011): 7001–26. http://dx.doi.org/10.5194/acp-11-7001-2011.
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Abstract. The isotopic composition of molecular hydrogen (H2) contains independent information for constraining the global H2 budget. To explore this, we have implemented hydrogen sources and sinks, including their stable isotopic composition and isotope fractionation constants, into the global chemistry transport model TM5. For the first time, a global model now includes a simplified but explicit isotope reaction scheme for the photochemical production of H2. We present a comparison of modelled results for the H2 mixing ratio and isotope composition with available measurements on seasonal to inter annual time scales for the years 2001–2007. The base model results agree well with observations for H2 mixing ratios. For δD[H2], modelled values are slightly lower than measurements. A detailed sensitivity study is performed to identify the most important parameters for modelling the isotopic composition of H2. The results show that on the global scale, the discrepancy between model and measurements can be closed by adjusting the default values of the isotope effects in deposition, photochemistry and the stratosphere-troposphere exchange within the known range of uncertainty. However, the available isotope data do not provide sufficient information to uniquely constrain the global isotope budget. Therefore, additional studies focussing on the isotopic composition near the tropopause and on the isotope effects in the photochemistry and deposition are recommended.
Rozprawy doktorskie na temat "Hydrogen isotopic composition"
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ZNEIMER, STEPHANIA. "Stable isotopic composition of southern Illinois precipitation from (2012-2017) summary". OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2578.
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This study examines variability in the isotopic composition of precipitation in southern Illinois, USA using a 5-year, event-based record, novel in its duration and in potential to extract important isotopic information of precipitation in a dynamic region, and the seasonality of major moisture sources. The isotopic composition of precipitation exhibited seasonal variations in δ18O and δ2H, where values are distinctively higher (lower) during summer (winter). Average values for d-excess were the highest (lowest) during autumn (summer). Seasonality is also present in events originating from the Gulf of Mexico (GOM), isolated by Langrangian methods. GOM JJA events showed more isotopically depleted precipitation than of non-GOM events due to a stronger “amount effect” signal (R2 = -0.40). To date, the amount effect has never been reported this far inland in the US. Precipitation analysis as it related to the ENSO phases exhibited statically significant differences in d-excess values. Precipitation events that occurred during a La Niña phase exhibited positive d¬-excess values, with an average value of 25.18‰. δ18O and δ2H values during El Niño phase were on average more depleted. Overall results highlight that the GOM, as a dominating moisture source, and ENSO phases can modulate the seasonal and intra-seasonal variability in the isotopic composition of precipitation in this region. The data collected, from a single location, can highlight moisture dynamics occurring on a regional scale and highlight the importance of the GOM as prevailing source of moisture for the Midwestern US. The second part of this study involved determining what were the best predictors for 18O and d-excess values. The study revealed that sea surface temperature and oxygen isotope values in the ambient vapor were the best predictors for 18O values but were the poorest predictors of d-excess values. The best predictors of d-excess were land surface characteristics such as the volumetric soil moisture, evaporation from bare soil variable, as well as SST, temperature of the air and specific humidity of the air. However, these predictors worked best with positive d-excess values that equaled or above 20‰.
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Leshin, Laurie Ann Stolper Edward M. Stolper Edward M. "The abundance and hydrogen isotopic composition of water in SNC meteorites : implications for water on Mars /". Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-11062007-091745.
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Snover, Amy Katherine. "The stable hydrogen isotopic composition of methane emitted from biomass burning and removed by oxic soils : application to the atmospheric methane budget /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11570.
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Burke, Roger Allen Jr. "Stable Hydrogen and Carbon Isotopic Compositions of Biogenic Methanes". Scholar Commons, 1985. https://scholarcommons.usf.edu/etd/7658.
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Stable hydrogen and carbon isotopic compositions of biogenic methanes collected from the sediments of several deep-sea, nearshore marine-estuarine, and freshwater environments were determined. The isotopic compositions of methane samples from eight different DSDP Sites (mean σD-CH4 = -1850>/∞, std. dev. = 70>/∞, n = 75; mean σ13C-CH4 = -71.30/∞, std. dev. = 6.30/∞, n = 44) are generally typical of methane formed via C02 reduction in deep-sea sediments.
Methane collected from several freshwater environments was D-depleted (mean σD-CH4 = -3000>/∞ , std. dev. = 260/∞, n = 20) and 13C-enriched (mean σ13C-CH4 = -60.10/∞, std. dev. = 6.10/∞, n = 20) compared to the deep-sea methane. Normally, acetate dissimilation is thought to account for about 60 to 70% of the total methane production in freshwater sediments.
Nearshore marine-estuarine methanes appear to be isotopically intermediate (mean σD-CH4 = -2580>/∞ , std. dev. = 230/∞, n = 46; σ13C-CH4 = -61.80/∞, std. dev. = 3.10/∞, n = 46) between deep-sea and freshwater methanes. Variation in the relative importance of the two main methanogenic pathways, acetate dissimilation and C02 reduction, is probably the single most important factor responsible for the differences in methane isotopic compositions among these three different types of environments. Other factors that probably contribute to the methane isotopic differences are temperature, sedimentation rate, organic matter type and amount, concentration of alternate electron acceptors, rate of methane formation and possibly postgenerative isotopic equilibration.
Shallow aquatic sediments are thought to be an important source of methane to the atmosphere; the methane produced in these systems, including the ones sampled in this study, is generally substantially more 13C-depleted than expected based on the σ13C of atmospheric methane and the isotopic fractionation associated with the atmospheric sink process. Too few oD data are available to allow evaluation of the role of shallow aquatic sediments in determining atmospheric σD-CH4.
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Clog, Matthieu. "Concentration et composition isotopique en hydrogène du manteau terrestre". Paris 7, 2010. http://www.theses.fr/2010PA077209.
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Contraindre la concentration et la composition isotopique de l'hydrogène dans le manteau terrestre apporte des informations cruciales sur le cycle global de l'eau et la nature des hétérogénéités mantelliques. Dans ce but, les bordures vitreuses des basaltes sont les échantillons les plus adaptés Lors de cette étude, 170 échantillons provenant de 4 rides océaniques et 2 points chauds ont été analysés pour leurs concentrations en eau et leur δ D. Au cours de ce travail, un biais analytique lié à l'utilisation de creusets en platine pour extraire le éléments volatils a été mis en évidence. L'utilisation de tubes en silice a donc été préférée. Les δD re-mesurés sur des échantillons précédemment analysés avec des creusets en platine sont en moyenne 15%o plus élevés. Le δ D et le rapport H2O/Ce présentent des hétérogénéités régionales et locales et constituent de traceurs de source. La source des basaltes de ride contient 175+/-70 ppm d'eau, et pour un S8\deltaSD de -61+/-6%o. Les MORB de l'océan Atlantique sont plus riches en eau (~250ppm in thé source) et en D ( δ D—57%o) que ceux de la dorsale Sud-Est Indienne (140 ppm et -63%o en moyenne), illustrant des processus de mélange différents également vus à travers les rapports Pb/Ce. L'étude de la dorsale Sud-Ouest Indienne a montré que δ D et H2O/Ce sont des traceurs du métasomatisme. Les concentrations en eau dans les sources des E-MORB et des OIB sont plu élevées et plus variables (entre 250 et 700 ppm). Les sources enrichies en eau et en élément incompatibles ont des δ D qui couvrent une gamme aussi large que celle des N-MORB (allant d -70 à -40%o). La confrontation avec les compositions isotopiques du néon et de Pb, Sr et Nd montre que le réservoir contenant des gaz rares primitifs est vraisemblablement pauvre en eau, et donc distinct du FOZO. Par conséquent, il est possible de recycler efficacement de l'eau sans en changer la composition isotopique en hydrogène dans certaines zones de subductionConstraining the concentration and isotopic composition of hydrogen in Earth's mantle brings crucial insights on the global water cycle and the nature of mantle heterogeneities. For this purpose, glassy rims of basalts are the best samples. In this study, 170 samples from 4 oceanic ridges and 2 hotspots were analysed for water content and ô D. During this work, we showed that using platinum crucibles to extract the volatiles was the cause of an analytical bias in earlier data. The use of silicate tubes was thus prefered. δ D re-measured on samples previously analyzed using platinum crucibles are, on average, 15%o higher. The δ D and the H2O/Ce ratio are hétérogeneous, both between areas and locally, and caracterize the sources. The source of N-MORB contains 175+/-70 ppm of water and has a δ D of -61+/-6%o. MORB from the Altantic ocean are richer in water (-250 ppm in the source) and D ( δ D—57%o), than those from thé South-East Indian (H2O~140 ppm and δ DS\simS-63%o), illustrating different mixing processes, also seen through the Pb/Ce ratios. The study of the MORB from the South-West Indian ridge showed that δ D and H2O/Ce are sensitive to metasomatism. The concentrations of water in E-MORB and OIB sources are higher and more variable (from 250 to 700 ppm). The ô D of water- and incompatible elements-enriched sources range from -70 to -40%o, showing as much variations as depleted sources. Confrontation with the isotopic compositions of Ne, Pb, Sr and Nd shows that the resevoir containing the primitive rare gases cannot be water-rich, and is thus different from the FOZO. Therefore, efficient recycling of water with no modification of its isotopic composition in hydrogen at subdcution zone can occur at some subduction zones
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Bates, Benjamin R. "Within Lake Spatial Variability of Long-chain n-alkanes and their Hydrogen Isotopic Compositions Adirondack Mountains, NY". University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535373859284956.
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Dawson, Daniel. "Stable hydrogen isotope ratios of individual hydrocarbons in sediments and petroleum". Thesis, Curtin University, 2006. http://hdl.handle.net/20.500.11937/1237.
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Early research into the stable hydrogen isotopic compositions (δD) of petroleum involved bulk deuterium/hydrogen (D/H) measurements which, while providing some useful information, had to contend with the analysis of complex mixtures of hydrocarbons, and alteration resulting from the rapid exchange of nitrogen-, oxygen- and sulphur-bound hydrogen. The use of gas chromatography-isotope ratio mass spectrometry (GC-irMS) overcomes these problems by allowing the analysis of individual compounds containing only the most isotopically conservative aliphatic carbon-bound (C-bound) hydrogen. This project investigates the geochemical utility and reliability of compound-specific δD values, with the aim to better understand and exploit this analytical capability. To demonstrate the source diagnostic potential of compound-specific δD values, normal and branched alkanes extracted from series of immature bog-head coals (torbanites) were analysed. The torbanites contain immature organic matter predominantly from a single, freshwater algal source, i.e. Botryococcus braunii (B. braunii). The δD values of n-alkanes reflect the climate regime at the time of deposition of the torbanites, and vary mainly in response to the δD values of the source meteoric waters in their depositional environments. n-Alkanes from torbanites deposited at high latitude in a glacial climate are depleted in D by up to 70% relative to those from a torbanite deposited at low latitude under a tropical climate regime. Torbanites deposited in a mid-latitude region under cool-temperate conditions contain n-alkanes with δD values falling in between those of n-alkanes from tropical and glacial torbanites.The δD values of the n-alkanes also reflect their multiple source inputs. For example, a saw-toothed profile of n-alkane δD values in Australian torbanites is attributed to a dual-source system: a predominant B. braunii input, with a minor terrestrial plant input to odd-carbon-numbered n-alkanes in the range n-C20 [subscript] to n-C29 [subscript]. The δD values of n-alkanes and isoprenoids (pristane and phytane) differ significantly in two Permian torbanites from Australia, thought to be reflective of the offset between the δD values of their precursors in extant organisms. The torbanite data indicate that a biological δD signal has been preserved for at least 260–280 million years, extending the utility of δD values for palaeoclimate studies. To elucidate the effect of sedimentary processes on the δD values of petroleum hydrocarbons, three sedimentary sequences have been studied. These comprise one from the Perth Basin (Western Australia) and two from the Vulcan Sub-basin (northern Australia) covering a wide range of maturities, i.e. 0.53–1.6% vitrinite reflectance (Ro). The δD values of n-alkanes extracted from immature-early mature sediments (marine shales/siltstones and mudstones) are consistent with that expected of marine-derived n-alkyl lipids. The hydrocarbons become enriched in D with increasing maturity. The large (ca. 115%) biologically-derived offset between the δD values of n-alkanes and acyclic isoprenoids from immature sediments gradually decreases with increasing maturity, as the isoprenoids become enriched in D more rapidly than the n-alkanes. The D-enrichment in isoprenoids correlates strongly with Ro and traditional molecular maturity parameters.This suggests that H/D exchange during maturation occurs via a mechanism involving carbocation-like intermediates, which proceeds more rapidly with compounds containing tertiary carbon centres. Significant epimerisation of pristane and phytane coincides with their D-enrichment, suggesting that hydrogen exchange occurs at their tertiary carbons. A mechanism is proposed which can account for both H/D exchange and the epimerisation of pristane and phytane in the sedimentary environment. Pristane and phytane extracted from a post-mature sediment from the Paqualin-1 sequence are significantly enriched in D (ca. 40%) relative to the n-alkanes, indicating that D-enrichment persists at very high maturity, and is more pronounced for the regular isoprenoids than the n-alkanes. This supports the notion that H/D exchange causes the observed shift in δD values, rather than free-radical hydrogen transfer. The differences between the δD values of pristane and phytane show opposite trends in the Perth Basin and Vulcan Sub-basin sediments. In the Perth Basin, phytane is enriched in D relative to pristane, likely due to a dominant algal source. In the Vulcan Sub-basin, pristane is enriched in D relative to phytane, and thus is attributed to a lower relative input of algal organic matter. The variance of the δD values of pristane and phytane is generally consistent throughout the maturity range and provides evidence that pristane and phytane exchange hydrogen at similar rates. δD analysis of crude oils and condensates reservoired in the Perth Basin and Vulcan Sub-basin has been carried out to evaluate potential applications in oil-source correlation.The n-alkanes from crude oils and condensates are often more enriched in D than n-alkanes extracted from their supposed source rocks, and the oils also show relatively small differences between the δD values of n-alkanes and isoprenoids. These results suggest significant H/D exchange has occurred, implying that the liquids were generated from mature source rocks. A Perth Basin crude oil (Gage Roads-1) thought to be derived from a lacustrine/terrestrial source contains hydrocarbons that are significantly depleted in D relative to Perth Basin oils derived from a marine source, attributed to variability in the isotopic composition of marine and terrestrial source waters. δD values of n-alkanes from Vulcan Sub-basin crude oils and condensates are largely consistent with their prior classification into two groups: Group A, having a marine source affinity; and Group B, having a terrigenous source affinity. Some oils and condensates are suggested to be mixtures of Group A and Group B hydrocarbons, or Group A hydrocarbons and other as yet unknown sources. An exception is a former Group A oil (Tenacious-1) containing n-alkanes that are enriched in D relative to those from other Group A oils and condensates, attributed to mixing with another source of more mature hydrocarbons. The n-alkane δD profile appears to be indicative of source and sedimentary processes. One Perth Basin crude oil (Dongara-14) contains lower-molecular-weight n-alkanes that are depleted in D relative to higher-molecular-weight n-alkanes, attributed to a mixed marine/terrestrial source.Group A crude oils and condensates from the Vulcan Sub-basin display a ‘bowl-shaped’ profile of n-alkane δD values. An upward inflection in the n-alkane δD profile from n-C11 [subscript] to n-C15 [subscript] is suggested to represent the addition of D-enriched lower-molecular-weight n-alkanes from a more mature wet gas/condensate to an initial charge of lower maturity oil. Ultimately, this project has demonstrated that the δD values of individual petroleum hydrocarbons can be used to elucidate the nature of source organic matter and depositional environments. The preservation potential of lipid δD values is greater than previously thought, although it is clear that H/D exchange accompanying maturation can have a significant effect on the δD values of certain hydrocarbons. Thus, great care must be taken when interpreting δD values of individual hydrocarbons, particularly those derived from sediments of high thermal maturity.
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Dawson, Daniel. "Stable hydrogen isotope ratios of individual hydrocarbons in sediments and petroleum". Curtin University of Technology, Department of Applied Chemistry, 2006. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=16839.
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Early research into the stable hydrogen isotopic compositions (δD) of petroleum involved bulk deuterium/hydrogen (D/H) measurements which, while providing some useful information, had to contend with the analysis of complex mixtures of hydrocarbons, and alteration resulting from the rapid exchange of nitrogen-, oxygen- and sulphur-bound hydrogen. The use of gas chromatography-isotope ratio mass spectrometry (GC-irMS) overcomes these problems by allowing the analysis of individual compounds containing only the most isotopically conservative aliphatic carbon-bound (C-bound) hydrogen. This project investigates the geochemical utility and reliability of compound-specific δD values, with the aim to better understand and exploit this analytical capability. To demonstrate the source diagnostic potential of compound-specific δD values, normal and branched alkanes extracted from series of immature bog-head coals (torbanites) were analysed. The torbanites contain immature organic matter predominantly from a single, freshwater algal source, i.e. Botryococcus braunii (B. braunii). The δD values of n-alkanes reflect the climate regime at the time of deposition of the torbanites, and vary mainly in response to the δD values of the source meteoric waters in their depositional environments. n-Alkanes from torbanites deposited at high latitude in a glacial climate are depleted in D by up to 70% relative to those from a torbanite deposited at low latitude under a tropical climate regime. Torbanites deposited in a mid-latitude region under cool-temperate conditions contain n-alkanes with δD values falling in between those of n-alkanes from tropical and glacial torbanites.The δD values of the n-alkanes also reflect their multiple source inputs. For example, a saw-toothed profile of n-alkane δD values in Australian torbanites is attributed to a dual-source system: a predominant B. braunii input, with a minor terrestrial plant input to odd-carbon-numbered n-alkanes in the range n-C20 [subscript] to n-C29 [subscript]. The δD values of n-alkanes and isoprenoids (pristane and phytane) differ significantly in two Permian torbanites from Australia, thought to be reflective of the offset between the δD values of their precursors in extant organisms. The torbanite data indicate that a biological δD signal has been preserved for at least 260–280 million years, extending the utility of δD values for palaeoclimate studies. To elucidate the effect of sedimentary processes on the δD values of petroleum hydrocarbons, three sedimentary sequences have been studied. These comprise one from the Perth Basin (Western Australia) and two from the Vulcan Sub-basin (northern Australia) covering a wide range of maturities, i.e. 0.53–1.6% vitrinite reflectance (Ro). The δD values of n-alkanes extracted from immature-early mature sediments (marine shales/siltstones and mudstones) are consistent with that expected of marine-derived n-alkyl lipids. The hydrocarbons become enriched in D with increasing maturity. The large (ca. 115%) biologically-derived offset between the δD values of n-alkanes and acyclic isoprenoids from immature sediments gradually decreases with increasing maturity, as the isoprenoids become enriched in D more rapidly than the n-alkanes. The D-enrichment in isoprenoids correlates strongly with Ro and traditional molecular maturity parameters.
This suggests that H/D exchange during maturation occurs via a mechanism involving carbocation-like intermediates, which proceeds more rapidly with compounds containing tertiary carbon centres. Significant epimerisation of pristane and phytane coincides with their D-enrichment, suggesting that hydrogen exchange occurs at their tertiary carbons. A mechanism is proposed which can account for both H/D exchange and the epimerisation of pristane and phytane in the sedimentary environment. Pristane and phytane extracted from a post-mature sediment from the Paqualin-1 sequence are significantly enriched in D (ca. 40%) relative to the n-alkanes, indicating that D-enrichment persists at very high maturity, and is more pronounced for the regular isoprenoids than the n-alkanes. This supports the notion that H/D exchange causes the observed shift in δD values, rather than free-radical hydrogen transfer. The differences between the δD values of pristane and phytane show opposite trends in the Perth Basin and Vulcan Sub-basin sediments. In the Perth Basin, phytane is enriched in D relative to pristane, likely due to a dominant algal source. In the Vulcan Sub-basin, pristane is enriched in D relative to phytane, and thus is attributed to a lower relative input of algal organic matter. The variance of the δD values of pristane and phytane is generally consistent throughout the maturity range and provides evidence that pristane and phytane exchange hydrogen at similar rates. δD analysis of crude oils and condensates reservoired in the Perth Basin and Vulcan Sub-basin has been carried out to evaluate potential applications in oil-source correlation.
The n-alkanes from crude oils and condensates are often more enriched in D than n-alkanes extracted from their supposed source rocks, and the oils also show relatively small differences between the δD values of n-alkanes and isoprenoids. These results suggest significant H/D exchange has occurred, implying that the liquids were generated from mature source rocks. A Perth Basin crude oil (Gage Roads-1) thought to be derived from a lacustrine/terrestrial source contains hydrocarbons that are significantly depleted in D relative to Perth Basin oils derived from a marine source, attributed to variability in the isotopic composition of marine and terrestrial source waters. δD values of n-alkanes from Vulcan Sub-basin crude oils and condensates are largely consistent with their prior classification into two groups: Group A, having a marine source affinity; and Group B, having a terrigenous source affinity. Some oils and condensates are suggested to be mixtures of Group A and Group B hydrocarbons, or Group A hydrocarbons and other as yet unknown sources. An exception is a former Group A oil (Tenacious-1) containing n-alkanes that are enriched in D relative to those from other Group A oils and condensates, attributed to mixing with another source of more mature hydrocarbons. The n-alkane δD profile appears to be indicative of source and sedimentary processes. One Perth Basin crude oil (Dongara-14) contains lower-molecular-weight n-alkanes that are depleted in D relative to higher-molecular-weight n-alkanes, attributed to a mixed marine/terrestrial source.
Group A crude oils and condensates from the Vulcan Sub-basin display a ‘bowl-shaped’ profile of n-alkane δD values. An upward inflection in the n-alkane δD profile from n-C11 [subscript] to n-C15 [subscript] is suggested to represent the addition of D-enriched lower-molecular-weight n-alkanes from a more mature wet gas/condensate to an initial charge of lower maturity oil. Ultimately, this project has demonstrated that the δD values of individual petroleum hydrocarbons can be used to elucidate the nature of source organic matter and depositional environments. The preservation potential of lipid δD values is greater than previously thought, although it is clear that H/D exchange accompanying maturation can have a significant effect on the δD values of certain hydrocarbons. Thus, great care must be taken when interpreting δD values of individual hydrocarbons, particularly those derived from sediments of high thermal maturity.
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Newberry, Sarah. "Molecular distributions and hydrogen isotopic compositions of n-alkanes from field studies of tree species : applications for paleoclimate studies". Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/49706/.
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The compound-specific δD values and molecular distributions of n-alkanes preserved in sediment archives are used as paleoclimate proxies. This use is based on two assumptions, 1) n-alkane δD values are highly correlated with source water δD values (Sachse 2012), and 2) the δD values of n-alkanes within a single site show little variation (Hou 2007). n-alkane molecular distributions are also used to infer the dominant source of n-alkanes input into sediment archives (Seki 2010). Despite this, paleoclimate reconstructions are being made without full understanding of how the δD values of nalkanes relate to the D isotopic compositions of meteoric waters in the region of synthesis, or how variable n-alkanes δD values could be within a single species. Using an in-depth investigation of Scots pine (Pinus sylvestris), significant variations in n-alkane molecular distributions and δD values were detected. These results suggest height of sample collection within a natural forest exerts a strong control on both n-alkane compositions, and δD values. Furthermore, this investigation indicates evergreen coniferous species synthesize both odd and even-chain-length n-alkanes, with high abundances of mid-chain n-alkanes, previously a diagnostic of aquatic plants. Both of these conclusions could significantly influence paleoclimate interpretations. Moreover, n-alkane δD values from Scots pine and Salix indicate little control of xylem water δD values on n-alkane δD values, suggesting that n-alkanes synthesized during spring are more representative of D-enriched stored assimilates. In addition, this study suggests too favourable conditions for photosynthesis could lead to reduced D-enrichment of leaf water, which is subsequently imprinted on the δD values of n-alkanes. These data suggest that under-estimations of climatic conditions present during the synthesis of n-alkane in sediments could occur if n-alkanes from existing plants are synthesized during periods of climatic stress.
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Jappy, Trevor George. "Compositional dependence of potassium-argon ages and hydrogen and oxygen stable isotopes in hornblendes from Connemara, Western Ireland". Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264263.
Pełny tekst źródłaKsiążki na temat "Hydrogen isotopic composition"
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Martin, Whalen, i United States. National Aeronautics and Space Administration., red. Carbon and hydrogen isotope composition and C concentration in methane from sources and from the atmosphere: Implications for a global methane budget. [Washington, DC: National Aeronautics and Space Administration, 1994.
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Martin, Whalen, i United States. National Aeronautics and Space Administration., red. Carbon and hydrogen isotope composition and ℗£þ́C concentration in methane from sources and from the atmosphere: Implications for a global methane budget. [Washington, DC: National Aeronautics and Space Administration, 1994.
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National Aeronautics and Space Administration (NASA) Staff. Carbon and Hydrogen Isotope Composition and C-14 Concentration in Methane from Sources and from the Atmosphere: Implications for a Global Methane Budget. Independently Published, 2018.
Znajdź pełny tekst źródłaCzęści książek na temat "Hydrogen isotopic composition"
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Quesnel, Benoît, Christophe Scheffer i Georges Beaudoin. "The Light Stable Isotope (Hydrogen, Boron, Carbon, Nitrogen, Oxygen, Silicon, Sulfur) Composition of Orogenic Gold Deposits". W Isotopes in Economic Geology, Metallogenesis and Exploration, 283–328. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-27897-6_10.
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AbstractOrogenic gold deposits formed in various terranes of most ages since the Paleoarchean and generally consist of quartz veins hosted in shear zones formed at the ductile brittle transition under greenschist to lower amphibolite metamorphic conditions. Vein mineralogy is dominated by quartz with various amounts of silicates, carbonates, phyllosilicates, borates, tungstates, sulfides, and oxides. The isotopic composition of these minerals and fluid inclusions has been investigated since the 1960s to constrain the characteristics of orogenic fluid systems involved in the formation of gold deposits worldwide. This review is based on 8580 stable isotope analyses, including δ18O, δD, δ13C, δ34S δ15N, δ11B, and δ30Si values, from 5478 samples from 558 orogenic gold deposits reported in the literature from 1960 to 2010. This contribution describes the variability of the light stable isotopic systems as function of the minerals, the age of the deposits, their regional setting, and their country rocks. The temperature of isotopic equilibrium of orogenic gold veins is estimated from mineral pairs for oxygen and sulfur isotopes. Based on these temperatures, and on fractionation between mineral and fluid components (H2O, CO2 and H2S), the isotopic composition of fluids is estimated to better constrain the main parameters shared by most of auriferous orogenic fluid systems. Orogenic gold deposits display similar isotopic features through time, suggesting that fluid conditions and sources leading to the formation of orogenic gold deposits did not change significantly from the Archean to the Cenozoic. No consistent secular variations of mineral isotope composition for oxygen (−8.1‰ ≤ δ18O ≤ 33‰, n = 4011), hydrogen (−187‰ ≤ δD ≤ −4‰, n = 246), carbon (−26.7‰ ≤ δ13C ≤ 12.3‰, n = 1179), boron (−21.6‰ ≤ δ11B ≤ 9‰, n = 119), and silicon (−0.5‰ ≤ δ30Si ≤ 0.8‰, n = 33) are documented. Only nitrogen (1.6‰ ≤ δ15N ≤ 23.7‰, n = 258) and sulfide sulfur from deposits hosted in sedimentary rocks (−27.2‰ ≤ δ34S ≤ 25‰, n = 717) display secular variations. For nitrogen, the change in composition is interpreted to record the variation of δ15N values of sediments devolatilized during metamorphism. For sulfur, secular variations reflect incorporation of local sedimentary sulfur of ultimate seawater origin. No significant variation of temperature of vein formation is documented for orogenic gold deposits of different ages. Quartz-silicate, quartz-carbonate and sulfide-sulfide mineral pairs display consistent temperatures of 360 ± 76 °C (1σ; n = 332), in agreement with the more common greenschist facies hostrocks and fluid inclusion microthermometry. Fluid sources for orogenic gold deposits are complex but the isotopic systems (hydrogen, boron, carbon, nitrogen, oxygen, sulfur) are most consistent with contributions from metamorphic fluids released by devolatilization of igneous, volcano-sedimentary and/or sedimentary rocks. The contribution of magmatic water exsolved from magma during crystallization is not a necessary component, even if permissible in specific cases. Isotopic data arrays can be interpreted as the result of fluid mixing between a high T (~550 °C)—high δ18O (~10‰)—low δD (~−60‰) deep-seated (metamorphic) fluid reservoir and a low T (~200 °C)—low δ18O (~2‰)—high δD (~0‰) upper crustal fluid reservoir in a number of orogenic gold deposits. The origin of the upper crustal fluid is most likely sea- or meteoric water filling the host rock porosity, with a long history of water–rock isotope exchange. Mixing of deep-seated and upper crustal fluids also explains the large variation of tourmaline δ11B values from orogenic gold veins. Regional spatial variations of oxygen and hydrogen isotope compositions of deep-seated fluid reservoirs are documented between orogenic gold districts. This is the case for the Val-d’Or (Abitibi), Coolgardie and Kalgoorlie (Yilgarn) where the oxygen isotope composition of the deep-seated fluid end-member is 4‰ lower compared to that from the Timmins, Larder Lake, and Kirkland Lake districts (Abitibi). However, both mixing trends converge towards a common, low δ18O upper crustal fluid end-member. Such variations cannot be related to fluid buffering at the site of deposition and suggest provinciality of the fluid source. The contribution of meteoric water is mainly recorded by fluid inclusions from Mesozoic and Cenozoic age deposits, but micas are not systematically in isotopic equilibrium with fluid inclusions trapped in quartz from the same vein. This suggests late involvement of meteoric water unrelated to deposit formation. Yet, a number of deposits with low δD mica may record infiltration of meteoric water in orogenic gold deposits. Isotope exchange between mineralizing fluid and country rocks is documented for oxygen, carbon, sulfur and silicon isotopes. Large variations (> 10‰) of sulfide δ34S values at the deposit scale are likely related to evolving redox conditions of the mineralizing fluid during reaction with country rocks. Deposits hosted in sedimentary rocks show a shift to higher δ18O values as a result of fluid/rock oxygen exchange with the regional sedimentary country rocks.
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Huston, David L., Robert B. Trumbull, Georges Beaudoin i Trevor Ireland. "Light Stable Isotopes (H, B, C, O and S) in Ore Studies—Methods, Theory, Applications and Uncertainties". W Isotopes in Economic Geology, Metallogenesis and Exploration, 209–44. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-27897-6_8.
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AbstractVariations in the abundances of light stable isotopes, particularly those of hydrogen, boron, carbon, oxygen and sulfur, were essential in developing mineralization models. The data provide constraints on sources of hydrothermal fluids, carbon, boron and sulfur, track interaction of these fluids with the rocks at both the deposit and district scales, and establish processes of ore deposition. In providing such constraints, isotopic data have been integral in developing genetic models for porphyry-epithermal, volcanic-hosted massive sulfide, orogenic gold, sediment-hosted base metal and banded-iron formation-hosted iron ore systems, as discussed here and in other chapters in this book. After providing conventions, definitions and standards used to present stable isotope data, this chapter summarizes analytical methods, both bulk and in situ, discusses processes that fractionate stable isotopes, documents the isotopic characteristics of major fluid and rock reservoirs, and then shows how stable isotope data have been used to better understand ore-forming processes and to provide vectors to ore. Analytical procedures, initially developed in the 1940s for carbon–oxygen analysis of bulk samples of carbonate minerals, have developed so that, for most stable isotopic systems, spots as small as a few tens of μm are routinely analyzed. This precision provides the paragenetic and spatial resolution necessary to answer previously unresolvable genetic questions (and create new questions). Stable isotope fractionation reflects geological and geochemical processes important in ore formation, including: (1) phase changes such as boiling, (2) water–rock interaction, (3) cooling, (4) fluid mixing, (5) devolatilization, and (6) redox reactions, including SO2 disproportionation caused by the cooling of magmatic-hydrothermal fluids and photolytic dissociation in the atmosphere. These processes commonly produce gradients in isotopic data, both in time and in space. These gradients, commonly mappable in space, provide not only evidence of process but also exploration vectors. Stable isotope data can be used to estimate the conditions of alteration or mineralization when data for coexisting minerals are available. These estimates use experimentally- or theoretically-determined fractionation equations to estimate temperatures of mineral formation. If the temperature is known from isotopic or other data (e.g., fluid inclusion data or chemical geothermometers), the isotopic composition of the hydrothermal fluid components can be estimated. If fluid inclusion homogenization and compositional data exist, the pressure and depth of mineralization can be estimated. One of the most common uses of stable isotope data has been to determine, or more correctly delimit, fluid and sulfur sources. Estimates of the isotopic compositions of hydrothermal fluids, in most cases, do not define unequivocal sources, but, rather, eliminate sources. As an example, the field of magmatic fluids largely overlap that of metamorphic fluids in δ18O-δD space, but are significantly different to the fields of meteoric waters and seawater. As such, a meteoric or seawater origin for a fluid source may be resolvable, but a magmatic source cannot be resolved from a metamorphic source. Similarly, although δ34S ~ 0‰ is consistent with a magmatic-hydrothermal sulfur source, the signature can also be produced by leaching of an igneous source. Recent analytical and conceptual advances have enabled gathering of new types of isotopic data and application of these data to resolve new problems in mineral deposit genesis and geosciences in general. Recent developments such as rapid isotopic analysis of geological materials or clumped isotopes will continue to increase the utility of stable isotope data in mineral deposit genesis and metallogeny, and, importantly, for mineral exploration.
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Ferronsky, V. I., i V. A. Polyakov. "Hydrogen and Oxygen Isotopic Composition of Groundwater in Volcanic Regions". W Isotopes of the Earth's Hydrosphere, 179–94. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-2856-1_9.
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Ferronsky, V. I., i V. A. Polyakov. "Hydrogen and Oxygen Isotopic Composition of Minerals of Magmatic and Metamorphic Rocks and Fluid Inclusions". W Isotopes of the Earth's Hydrosphere, 195–204. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-2856-1_10.
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Ferronsky, V. I., i V. A. Polyakov. "Hydrogen and Oxygen Isotopic Composition of Sedimentary Rocks of Marine Genesis and Implications for Paleothermometry". W Isotopes of the Earth's Hydrosphere, 155–78. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-2856-1_8.
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Allen, Scott T., Matthias Sprenger, Gabriel J. Bowen i J. Renée Brooks. "Spatial and Temporal Variations in Plant Source Water: O and H Isotope Ratios from Precipitation to Xylem Water". W Stable Isotopes in Tree Rings, 501–35. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_18.
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AbstractThe water present within trees when sugars and cellulose are formed is the source of hydrogen and oxygen atoms that are incorporated into tree-ring cellulose (see Chaps. 10.1007/978-3-030-92698-4_10 and 10.1007/978-3-030-92698-4_11). However, the isotope composition of relevant water pools is often unknown when trying to interpret δ18O and δ2H isotopic records in tree rings. This chapter focuses on the factors that can influence the O and H isotope ratios of source waters for trees. Trees generally use water that originated as precipitation, but this does not mean that the isotope ratios of water used by trees—predominantly taken up by roots from soils—and incorporated in cellulose exactly matches precipitation isotope ratios. Precipitation isotope ratios vary in space and time, and only a fraction of all precipitation infiltrates soils, reaches roots, and is ultimately taken up by trees. Considering species, soils, and climates may allow for predicting which fraction of water resides in the root-zone during the growing seasons, and how its isotope ratios deviate from that of average precipitation. Here we provide an overview of the terrestrial water cycle and the associated transport and fractionation processes that influence the stable isotope ratios of water used by trees. We highlight obstacles and opportunities to be considered, towards more accurately interpreting the records of O and H isotope ratios in tree cellulose.
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Allen, Scott T., Matthias Sprenger, Gabriel J. Bowen i J. Renée Brooks. "Spatial and Temporal Variations in Plant Source Water: O and H Isotope Ratios from Precipitation to Xylem Water". W Stable Isotopes in Tree Rings, 501–35. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_18.
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AbstractThe water present within trees when sugars and cellulose are formed is the source of hydrogen and oxygen atoms that are incorporated into tree-ring cellulose (see Chaps. 10.1007/978-3-030-92698-4_10 and 10.1007/978-3-030-92698-4_11). However, the isotope composition of relevant water pools is often unknown when trying to interpret δ18O and δ2H isotopic records in tree rings. This chapter focuses on the factors that can influence the O and H isotope ratios of source waters for trees. Trees generally use water that originated as precipitation, but this does not mean that the isotope ratios of water used by trees—predominantly taken up by roots from soils—and incorporated in cellulose exactly matches precipitation isotope ratios. Precipitation isotope ratios vary in space and time, and only a fraction of all precipitation infiltrates soils, reaches roots, and is ultimately taken up by trees. Considering species, soils, and climates may allow for predicting which fraction of water resides in the root-zone during the growing seasons, and how its isotope ratios deviate from that of average precipitation. Here we provide an overview of the terrestrial water cycle and the associated transport and fractionation processes that influence the stable isotope ratios of water used by trees. We highlight obstacles and opportunities to be considered, towards more accurately interpreting the records of O and H isotope ratios in tree cellulose.
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Burke, Roger A., i William M. Sackett. "Stable Hydrogen and Carbon Isotopic Compositions of Biogenic Methanes from Several Shallow Aquatic Environments". W ACS Symposium Series, 297–313. Washington, DC: American Chemical Society, 1986. http://dx.doi.org/10.1021/bk-1986-0305.ch017.
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Wright, I. P. "Stable Isotopic Compositions of Hydrogen, Carbon, Nitrogen, Oxygen and Sulfur in Meteoritic Low Temperature Condensates". W Ices in the Solar System, 221–49. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5418-2_15.
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Walker, James C. G. "How to Calculate Isotope Ratios". W Numerical Adventures with Geochemical Cycles. Oxford University Press, 1991. http://dx.doi.org/10.1093/oso/9780195045208.003.0008.
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The calculation of isotope ratios requires special consideration because isotope ratios, unlike matter or energy, are not conserved. In this chapter I shall show how extra terms arise in the equations for the rates of change of isotope ratios. The equations developed here are quite general and can be applied to most of the isotope systems used in geochemistry. As an example of the application of these new equations, I shall demonstrate a simulation of the carbon isotopic composition of ocean and atmosphere and then use this simulation to examine the influence on carbon isotopes of the combustion of fossil fuels. As an alternative application I shall simulate the carbon isotopic composition of the water in an evaporating lagoon and show how the composition and other properties of this water might be affected by seasonal changes in evaporation rate, water temperature, and biological productivity. Equations for the rates of change of individual isotopes in a reservoir are not essentially different from the equations for the rates of change of chemical species. Isotopic abundances, however, are generally expressed as ratios of one isotope to another and, moreover, not just as the ratio but also as the departure of the ratio from a standard. This circumstance introduces some algebra into the derivation of an isotopic conservation equation. It is convenient to pursue this algebra just once, as I shall in this section, after which all isotope simulations can be formulated in the same way. I shall use the carbon isotopes to illustrate this derivation, but the same approach can be used for the isotopes of other elements, such as sulfur, oxygen, nitrogen, hydrogen, or strontium. The most abundant isotope of carbon has a mass of 12 atomic mass units, 12C. A less abundant stable isotope is 13C. And much less abundant is the radioactive isotope 14C, also called radiocarbon. It is convenient to express the abundances of these rare isotopes in terms of ratios of the number of atoms of the rare isotope in a sample to the number of atoms of the abundant isotope. We call this ratio r, generally a very small number.
Streszczenia konferencji na temat "Hydrogen isotopic composition"
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Ahsan, Dr Syed Asif, Reem Ali Mabkhout AlSeiari, Dr Tamer Koksalan i Yatindra Bhushan. "Assessment of Sweep Efficiency and Breakthrough Using CO2, H2O, Carbon and Hydrogen Isotope Composition in a Water Alternating with Gas EOR Project in Onshore Abu Dhabi, UAE". W Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/208211-ms.
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Abstract Measuring sweep efficiency and understanding breakthrough are the most important parameters to assess an Enhanced Oil Recovery (EOR) project having Water Alternating with miscible CO2 Gas (WAG) injection. The objective of this study was to use CO2, H2O and isotope compositions to assess sweep efficiency and breakthrough in producer wells in an ADNOC Onshore field in order to take the necessary actions for project optimization (e.g., injector and/or future producer well location optimization). CO2 and H2O compositions, along with their respective carbon and hydrogen isotopes, was integrated with downhole pressure gauge data to evaluate the impact of WAG operation on EOR. It was understood at the start of the project that an isotopically distinct injected CO2, compared to the oil associated CO2, would assist in the evaluation of sweep efficiency and breakthrough. The injected CO2 used in the WAG comes from a steel mill that is isotopically very distinct (i.e., significantly light) from the oil associated CO2. CO2 and H2O are injected periodically in the reservoir through designated injectors distributed over the field. The initially produced oil associated CO2, H2O, carbon and hydrogen isotope values were available as reference to measure the extent of sweep efficiency and breakthrough. Injected H2O and CO2 compositions and their respective hydrogen and carbon isotope values are measured at each injection cycle (so called campaigns). This is then followed by periodic compositional and isotopic measurements of the same components in oil and water producer wells to measure the extent of breakthrough. CO2, H2O composition and carbon and hydrogen isotope measurements in injector and producer wells indicate that the injected CO2 is preferentially breaking through in certain parts of the field. This indicates heterogeneous reservoir quality distribution throughout the field with better reservoir quality (e.g. higher permeability) between injector and producer wells having faster breakthrough. The compositional and isotopic measurements are sensitive enough to register compositional changes in the producer wells relatively faster than assessed by downhole pressure gauges.
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Keisling, Benjamin Andrew, Julie Brigham-Grette, Jeffrey M. Salacup i Isla S. Castañeda. "RECONSTRUCTING ARCTIC HYDROLOGY USING THE HYDROGEN ISOTOPIC COMPOSITION OF LEAF WAXES". W 51st Annual Northeastern GSA Section Meeting. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016ne-272670.
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Dixon, Jacqueline, Ilya N. Bindeman i Richard Kingsley. "HYDROGEN ISOTOPIC COMPOSITION OF ENRICHED MANTLE SOURCES: RESOLVING THE DEHYDRATION PARADOX". W GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-298878.
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Lehmann, Marco, Philipp Schuler, Valentina Vitali, Matthias Saurer, Marc-André Cormier i Guido Wiesenberg. "The hydrogen isotopic composition of plant carbohydrates – Advancement in methods and interpretation". W Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.9425.
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Chikaraishi, Y. "Hydrogen Isotopic Composition of Fatty Acids, Sterols, and Phytol: Autotrophic Vs. Heterotrophic Production". W 29th International Meeting on Organic Geochemistry. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201902871.
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Ogliore, Ryan, Gerardo Dominguez i Lauren Tafla. "Oxygen and Hydrogen Isotopic Composition of Zag Water Measured by Cavity Ring-down Spectroscopy". W Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.5438.
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Haettig, K., D. Varma, S. Schouten i M. T. J. Van der Meer. "LARGE REGIONAL GLACIAL-INTERGLACIAL CHANGES IN HYDROGEN ISOTOPIC COMPOSITION OF ALKENONES NEAR THE CHILEAN MARGIN". W 30th International Meeting on Organic Geochemistry (IMOG 2021). European Association of Geoscientists & Engineers, 2021. http://dx.doi.org/10.3997/2214-4609.202134103.
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APICELLA, M., V. VIOLANTE, F. SARTO, A. ROSADA, E. SANTORO, E. CASTAGNA, C. SIBILIA, M. MCKUBRE, F. TANZELLA i G. HUBLER. "PROGRESS ON THE STUDY OF ISOTOPIC COMPOSITION IN METALLIC THIN FILMS UNDERGONE TO ELECTROCHEMICAL LOADING OF HYDROGEN". W Proceedings of the 12th International Conference on Cold Fusion. WORLD SCIENTIFIC, 2006. http://dx.doi.org/10.1142/9789812772985_0026.
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Mayorov, A. G. "MEASUREMENT OF THE ISOTOPIC COMPOSITION OF HYDROGEN AND HELIUM NUCLEI IN COSMIC RAYS WITH THE PAMELA-EXPERIMENT". W The 34th International Cosmic Ray Conference. Trieste, Italy: Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.236.0270.
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Laurinat, James E., Neal M. Askew i Steve J. Hensel. "Flammability Analysis for Actinide Oxides Packaged in 9975 Shipping Containers". W ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97478.
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Packaging options are evaluated for compliance with safety requirements for shipment of mixed actinide oxides packaged in a 9975 Primary Containment Vessel (PCV). Radiolytic gas generation rates, PCV internal gas pressures, and shipping windows (times to reach unacceptable gas compositions or pressures after closure of the PCV) are calculated for shipment of a 9975 PCV containing a plastic bottle filled with plutonium and uranium oxides with a selected isotopic composition. G-values for radiolytic hydrogen generation from adsorbed moisture are estimated from the results of gas generation tests for plutonium oxide and uranium oxide doped with curium-244. The radiolytic generation of hydrogen from the plastic bottle is calculated using a geometric model for alpha particle deposition in the bottle wall. The temperature of the PCV during shipment is estimated from the results of finite element heat transfer analyses.
Raporty organizacyjne na temat "Hydrogen isotopic composition"
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Lacerda Silva, P., G. R. Chalmers, A. M. M. Bustin i R. M. Bustin. Gas geochemistry and the origins of H2S in the Montney Formation. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329794.
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The geology of the Montney Formation and the geochemistry of its produced fluids, including nonhydrocarbon gases such as hydrogen sulfide were investigated for both Alberta and BC play areas. Key parameters for understanding a complex petroleum system like the Montney play include changes in thickness, depth of burial, mass balance calculations, timing and magnitudes of paleotemperature exposure, as well as kerogen concentration and types to determine the distribution of hydrocarbon composition, H2S concentrations and CO2 concentrations. Results show that there is first-, second- and third- order variations in the maturation patterns that impact the hydrocarbon composition. Isomer ratio calculations for butane and propane, in combination with excess methane estimation from produced fluids, are powerful tools to highlight effects of migration in the hydrocarbon distribution. The present-day distribution of hydrocarbons is a result of fluid mixing between hydrocarbons generated in-situ with shorter-chained hydrocarbons (i.e., methane) migrated from deeper, more mature areas proximal to the deformation front, along structural elements like the Fort St. John Graben, as well as through areas of lithology with higher permeability. The BC Montney play appears to have hydrocarbon composition that reflects a larger contribution from in-situ generation, while the Montney play in Alberta has a higher proportion of its hydrocarbon volumes from migrated hydrocarbons. Hydrogen sulphide is observed to be laterally discontinuous and found in discrete zones or pockets. The locations of higher concentrations of hydrogen sulphide do not align with the sulphate-rich facies of the Charlie Lake Formation but can be seen to underlie areas of higher sulphate ion concentrations in the formation water. There is some alignment between CO2 and H2S, particularly south of Dawson Creek; however, the cross-plot of CO2 and H2S illustrates some deviation away from any correlation and there must be other processes at play (i.e., decomposition of kerogen or carbonate dissolution). The sources of sulphur in the produced H2S were investigated through isotopic analyses coupled with scanning electron microscopy, energy dispersive spectroscopy, and mineralogy by X-ray diffraction. The Montney Formation in BC can contain small discrete amounts of sulphur in the form of anhydrite as shown by XRD and SEM-EDX results. Sulphur isotopic analyses indicate that the most likely source of sulphur is from Triassic rocks, in particular, the Charlie Lake Formation, due to its close proximity, its high concentration of anhydrite (18-42%), and the evidence that dissolved sulphate ions migrated within the groundwater in fractures and transported anhydrite into the Halfway Formation and into the Montney Formation. The isotopic signature shows the sulphur isotopic ratio of the anhydrite in the Montney Formation is in the same range as the sulphur within the H2S gas and is a lighter ratio than what is found in Devonian anhydrite and H2S gas. This integrated study contributes to a better understanding of the hydrocarbon system for enhancing the efficiency of and optimizing the planning of drilling and production operations. Operators in BC should include mapping of the Charlie Lake evaporites and structural elements, three-dimensional seismic and sulphate ion concentrations in the connate water, when planning wells, in order to reduce the risk of encountering unexpected souring.
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Kingston, A. W., O. H. Ardakani, G. Scheffer, M. Nightingale, C. Hubert i B. Meyer. The subsurface sulfur system following hydraulic stimulation of unconventional hydrocarbon reservoirs: assessing anthropogenic influences on microbial sulfate reduction in the deep subsurface, Alberta. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330712.
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Hydraulic fracturing is a reservoir stimulation technique that involves the injection of high-pressure fluids to enhance recovery from unconventional hydrocarbon reservoirs. Often this involves the injection of surface waters (along with additives such as biocides) into formational fluids significantly different isotopic and geochemical compositions facilitating geochemical fingerprinting of these fluid sources. In some instances, the produced fluids experience an increase in hydrogen sulfide (H2S) concentration over the course of production resulting in an increased risk to health and safety, the environment, and infrastructure due to the toxic and corrosive nature of H2S. However, questions remain as to the origin and processes leading to H2S formation following hydraulic fracturing. In this study, we analyzed a series of produced waters following hydraulic fracturing of a horizontal well completed in the Montney Formation, Western Canada to evaluate variations in geochemical and microbiological composition over time and characterize potential sulfur species involved in the production of H2S. Initially, sulfur isotope ratios (d34S, VCDT) of dissolved sulfate in produced water had a baseline value of 27per mil similar to the d34S value of 25per mil for solid anhydrite derived from core material. Subsequently, d34S values of sulfate in produced fluids sequentially increased to 35per mil coincident with the appearance of sulfides in produced waters with a d34SH2S value of 18per mil. Oxygen isotope values of dissolved sulfate exhibited a synchronous increase from 13.2per mil to 15.8per mil VSMOW suggesting sulfate reduction commenced in the subsurface following hydraulic fracturing. Formation temperatures are &lt;100°C precluding thermochemical sulfate reduction as a potential mechanism for H2S production. We suggest that microbial reduction of anhydrite-derived sulfate within the formation is likely responsible for the increase in H2S within produced waters despite the use of biocides within the hydraulic fracturing fluids. Initial assessments of microbial communities indicate a shift in community diversity over time and interactions between in situ communities and those introduced during the hydraulic fracturing process. This study indicates that biocides may not be fully effective in inhibiting microbial sulfate reduction and highlights the role anthropogenic influences such as hydraulic fracturing can have on the generation of H2S in the subsurface.
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Boreham, C. J., L. Wang, J. Sohn, N. Jinadasa, Z. Hong, J. Chen, E. Grosjean i A. Jarrett. Exploring for the Future - NDI Carrara 1 gas geochemistry: molecular composition, carbon and hydrogen isotopes of hydrocarbon gases, and the sources of molecular hydrogen and helium. Geoscience Australia, 2022. http://dx.doi.org/10.11636/record.2022.014.
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Liseroudi, M. H., O. H. Ardakani, P. K. Pedersen, R. A. Stern, J M Wood i H. Sanei. Diagenetic and geochemical controls on H2S distribution in the Montney Formation, Peace River region, western Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329785.
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The Lower Triassic Montney Formation is a major siltstone dominated unconventional tight gas play in the Western Canadian Sedimentary Basin (WCSB). In the Peace River region, the Montney Formation contains a regionally variable amount of hydrogen sulfide (H2S) in gas-producing wells with western Alberta's wells having the highest concentrations. Previous studies on the source and distribution of H2S in the Montney Formation mainly focused on variations of H2S concentration and its relationship with other hydrocarbon and non-hydrocarbon gases, sulfur isotope composition of H2S, as well as organo-sulfur compounds in the Montney Formation natural gas. None of those studies, however, focused on the role of diagenetic and geochemical processes in the formation of dissolved sulfate, one of the two major ingredients of H2S formation mechanisms, and pyrite within the Montney Formation. According to the results of this study, the Montney Formation consists of two different early and late generations of sulfate minerals (anhydrite and barite), mainly formed by the Montney Formation pore water and incursion of structurally-controlled Devonian-sourced hydrothermal sulfate-rich fluids. In addition, pyrite the dominate sulfide mineral, occurred in two distinct forms as framboidal and crystalline that formed during early to late stages of diagenesis in western Alberta (WAB) and northeast British Columbia (NEBC). The concurrence of the late-stage anhydrite and barite and various types of diagenetic pyrite with high H2S concentrations, particularly in WAB, their abundance, and spatial distribution, imply a correlation between the presence of these sulfate and sulfide species and the diagenetic evolution of sulfur in the Montney Formation. The sulfur isotope composition of anhydrite/barite, H2S, and pyrite demonstrates both microbial and thermochemical sulfate reduction (MSR and TSR) controlled the diagenetic sulfur cycle of the Montney Formation. The relationship between the delta-34S values of the present-day produced gas H2S and other sulfur-bearing species from the Montney and other neighboring formations verifies a dual native and migrated TSR-derived origin for the H2S gas with substantial contributions of in situ H2S in the Montney reservoir.