Distribution Of Hydrogen Isotopes Research Articles

Theoretical and experimental constraints on hydrogen isotope equilibrium in C1-C5 alkanes

Stable isotope ratios of C1–C5 alkanes, the major constituents of subsurface gaseous hydrocarbons, can provide valuable insights on their origins, transport, and fates. Equilibrium isotope effects are fundamental to interpreting stable isotope signatures, as recognition of them in natural materials indicates reversible processes and constrains the temperatures of equilibrated systems. Hydrogen isotope equilibrium of C1–C5 alkanes is of particular interest because evidence shows that alkyl H can undergo isotopic exchange with coexisting compounds under subsurface conditions. We present the results of a combined experimental and theoretical effort to determine equilibrium hydrogen isotope distributions in mixtures of these hydrocarbon compounds. We created two mixtures: one with C1, C2 and C3 (where C1 indicates methane, C2 ethane, etc., hereinafter called ‘C1–C3 mixture’) and another one with C2, C3, iC4, nC4, iC5 and nC5 (hereinafter called ‘C2–C5 mixture’); in both cases, the mixtures were created to start out of hydrogen isotope equilibrium. We tested the performance of several metal catalysts as aids to H isotopic exchange by exposing these mixtures to different metal catalysts at 100 or 200 °C and analyzing the compound-specific hydrogen isotope ratios of the product gases. The C1–C3 mixture exchanged hydrogen isotopes among the starting gas components rapidly in the presence of Ru/Al2O3 at 200 °C. The isotope ratios reach a steady-state (presumably equilibrium) after 72 h of heating (up to 120 h). The hydrogen isotopic ratios of alkanes in the C2–C5 mixture shifted significantly in the presence of Rh/Al2O3 at 100 °C and C3-C5 compounds approached steady state after 70 h, whereas C2 had not yet reached a steady state D/H ratio after 216 h of heating. We evaluated the reaction progress of isotope exchange for each compound as a function of time with a reaction-network model informed by constraints on chemical kinetics. The model indicates that C3, iC4, nC4, iC5 and nC5 in the C2-C5 mixture reached internal isotope equilibrium after 70 h, hence we used their values to calculate experimental equilibrium results. We also calculated equilibrium isotope fractionations with the Bigeleisen-Mayer theorem using vibrational frequencies computed from the density functional theory (B3LYP/aug-cc-pVTZ). We included torsional conformers and explicit H positions in the calculations. We found that the experimental results from both the 200 ˚C C1–C3 experiment and 100 ˚C C2–C5 experiment are consistent with theoretical equilibrium results within experimental uncertainty. Additionally, our reaction-network model for catalyzed hydrogen isotope exchange between alkanes succeeded in fitting our experimental results. This modeling framework can be adjusted to simulate exchange in natural settings for constraining temperature histories and sources of natural gases.

A rapid method for the determination of stable hydrogen isotope ratios of acetic acid in vinegar.

Vinegar is an everyday condiment made from fermented grains or fruits. It contains acetic acid which is the main organic material produced by fermentation. Vinegar suffers from the authenticity problem of exogenous adulteration due to the indistinguishability of low-cost chemical sources of synthetic acetic acid from acetic acid produced by fermentation. It is necessary to establish a simple and rapid measurement technique. Determination was according to the total acid content of vinegar diluted with acetone to a certain concentration. Online separation and determination of acetic acid δD in vinegar were carried out using gas chromatography-pyrolysis-isotope ratio mass spectrometry. An HP-Plot/U column was selected for online separation of acetic acid and water with molecular sieve characteristics. At the same time, combined with the instrument blowback function to remove water. Dilute solvent acetone was treated with a molecular sieve to remove trace water. The reproducibility of this method is less than 3‰. The long-term stability is within a reasonable error range. The accuracy correlation coefficient is greater than 0.99. The δD values of acetic acid in vinegar (-264.5 ± 20.3‰) and from chemical sources (-30.5 ± 90.8‰) were obtained. A rapid method was developed for identification of different sources of acetic acid. These different sources of acetic acid exhibited significant hydrogen isotope distribution characteristics. Additionally, it was observed that the carboxyl hydrogen of acetic acid exhibited facile exchange with water. In future investigations, we aim to mitigate this interference.

Genetic identification of light oils and condensates using δD indices of C7 hydrocarbons: A case study in the Tarim Basin, NW China

Generally, the low concentration and homogenisation of traditional biomarkers in light oil and condensate (LOC) lead to uncertainties in their indicative significance of the parental origin of crude oils. Here, we focus on the component and stable hydrogen isotope (δD) distribution of C7 light hydrocarbons, including n-heptane (nC7), methylcyclohexane (MCH) and toluene (Tol), to identify the source rocks of LOC. In total, 114 LOCs whose source rocks are believed to be marine, lacustrine or coal facies in the Tarim Basin, NW China, are selected for the case study. The results demonstrate that the δDMCH, δDTol and δDnC7 values in the LOCs from marine, lacustrine and coal facies exhibited strong, slight and inverse ‘V' distributions, respectively, on their Line Charts. By analysing the differences among these values, we found that the ΔδDnC7–Tol and ΔδDTol–MCH values in the LOCs show good linear correlation (R2 = 0.8) and have the potential to distinguish the sedimentary facies of the source rocks of these oils. The ΔδDnC7–Tol values for marine, lacustrine and coal-formed LOCs were ˃6‰, from −20‰ to 20‰, and < −20‰, respectively. Further, the ΔδDTol–MCH values in the marine, lacustrine and coal-formed LOCs are ˂ − 5‰, from −30‰ to ‰, and > 0‰, respectively. Thus, the plot of ΔδDnC7–Tol–ΔδDTol–MCH can effectively distinguish among marine, lacustrine and coal-formed LOCs.

A method for predicting hydrogen and oxygen isotope distributions across a region's river network using reach-scale environmental attributes

Abstract. Stable isotope ratios (isotope values) of surface water reflect hydrological pathways, mixing processes, and atmospheric exchange within catchments. Development of maps of surface water isotope values (isoscapes) is limited by methods to interpolate point measures across river networks. Catchment attributes that alter surface water isotope values affect downstream river reaches via flow, but some attributes such as artificial dams are no more likely to affect nearby unconnected catchments than distant ones. Hence, simple distance-based geospatial and statistical interpolation methods used to develop isoscapes for precipitation and terrestrial systems are less appropriate for river networks. We used a water-balance-based method to map long-term average δ2H and δ18O for New Zealand rivers, incorporating corrections using catchment environmental predictors. Inputs to the model are national rainfall precipitation isoscapes, a digital elevation layer, a national river water isotope monitoring dataset (3 years of monthly sampling at 58 sites), and river environmental databases covering around 600 000 reaches and over 400 000 km of rivers. Much of the spatial variability in δ2H and δ18O of New Zealand river water was explained using the initial combination of precipitation isoscapes and a simple water balance model. δ2H and δ18O isoscapes produced by subsequently applying residuals from the water balance model as a correction factor across the river network using regression kriging showed improved fits to the validation data compared to the correction using ordinary kriging. Predictors of high importance in the regression included upstream lake and wetland area, which was not strongly spatially autocorrelated nationally. Hence, additional hydrological process information such as evaporation effects can be incorporated into river isoscapes using regression kriging of residuals. The resulting isoscapes have potential applications in ecological, hydrological, and provenance studies that consider differences between surface water isotope values and those of other components of the hydrological cycle (e.g. subsurface runoff or local precipitation).

Produced Gas and Condensate Geochemistry of the Marcellus Formation in the Appalachian Basin: Insights into Petroleum Maturity, Migration, and Alteration in an Unconventional Shale Reservoir

The Middle Devonian Marcellus Formation of North America is the most prolific hydrocarbon play in the Appalachian basin, the second largest producer of natural gas in the United States, and one of the most productive gas fields in the world. Regional differences in Marcellus fluid chemistry reflect variations in thermal maturity, migration, and hydrocarbon alteration. These differences define specific wet gas/condensate and dry gas production in the basin. Marcellus gases co-produced with condensate in southwest Pennsylvania and northwest West Virginia are mixtures of residual primary-associated gases generated in the late oil window and postmature secondary hydrocarbons generated from oil cracking in the wet gas window. Correlation of API gravity and C7 expulsion temperatures, high heptane and isoheptane ratios, and the gas geochemical data confirm that the Marcellus condensates formed through oil cracking. Respective low toluene/nC7 and high nC7/methylcyclohexane ratios indicate selective depletion of low-boiling point aromatics and cyclic light saturates in all samples, suggesting that water washing and gas stripping altered the fluids. These alterations may be related to deep migration of hot basinal brines. Dry Marcellus gases produced in northeast Pennsylvania and northcentral West Virginia are mixtures of overmature methane largely cracked from refractory kerogen and ethane and propane cracked from light oil and wet gas. Carbon and hydrogen isotope distributions are interpreted to indicate (1) mixing of hydrocarbons of different thermal maturities, (2) high temperature Rayleigh fractionation of wet gas during redox reactions with transition metals and formation water, (3) isotope exchange between methane and water, and, possibly, (4) thermodynamic equilibrium conditions within the reservoirs. Evidence for thermodynamic equilibrium in the dry gases includes measured molecular proportions (C1/(C1 − C5) = 0.96 to 0.985) and δ13C1 values significantly greater than δ13CKEROGEN. Noble gas systematics support the interpretation of hydrocarbon–formation water interactions, constrain the high thermal maturity of the hydrocarbon fluids, and provide a method of quantifying gas retention versus expulsion in the reservoirs.

Intramolecular hydrogen isotope exchange inside silicate melts – The effect of deuterium concentration

Tracing the deep geological water cycle requires knowledge of the hydrogen isotope systematics between and within hydrous materials. For quenched hydrous alkali-silicate melts, hydrogen NMR reveals a distinct heterogeneity in the distribution of stable hydrogen isotopes (D, H) within the silicate tetrahedral network, where deuterons concentrate strongly in network regions that are associated with alkali cations. Previous hydrogen NMR studies performed in the sodium tetrasilicate system (Na2O x 4SiO2, NS4) with a 1:1 D2O/H2O ratio showed on average 1300 ‰ deuterium enrichment in the alkali-associated network, but the effect on varying bulk D2O/H2O ratios on this intramolecular isotope effect remained unconstrained. Experiments in the hydrous sodium tetrasilicate system with 8 wt% bulk water and varying bulk D2O/H2O ratios were performed at 1400 °C and 1.5 GPa. It is found that both hydrogen isotopes preferably partition into the silicate network that is associated with alkali ions. The partitioning is always stronger for the deuterated than for the protonated hydrous species. The relative enrichment of deuterium over protium in the alkali-associated network, i.e., the intramolecular isotope effect, correlates positively with the D2O/H2O bulk ratio of the hydrous NS4 system. Modeled for natural deuterium abundance (D/H near 1.56 × 10−4), a 1.4-fold (c. 340 ‰) deuterium enrichment in the alkali-associated silicate network is predicted. The partitioning model further predicts a positive correlation between the bulk water content of the silicate melt and the intramolecular deuterium partitioning into the alkali-associated silicate network. Such heterogeneities may explain the magnitude and direction of hydrogen isotope fractionation in hydrous silicate melts coexisting with silicate-saturated fluids. As such, this intramolecular isotope effect appears to be an effective mechanism for deuterium separation, particularly in hydrous magmatic settings, such as subduction zones.

Hydrogen isotope inventory evaluation of hydrogen isotopes separation system of CFETR using Aspen Plus simulator

The tritium plant needs to recover unburned deuterium and tritium for recycling to achieve tritium self-sufficiency. The tritium recovered by the water detritiation system (WDS) contains a large amount of protium. High purity deuterium (D) and tritium (T) are required as fuel for fusion reactor while hydrogen (H) always exists as an impurity of the fuel. Therefore, a hydrogen isotope separation system (ISS) is essential for fuel cycle in fusion reactor. ISS separates the recovered H, D, T, and removes the impurity protium (H) to obtain high-purity fuel deuterium and tritium. In this paper, two hydrogen isotope separation systems for the inner fuel cycle system and the outer fuel cycle system of CFETR (China Fusion Engineering Test Reactor) are respectively established according to the disparity in tritium concentration of hydrogen isotopes gas. The tritium inventory in the ISS is expected to be very large, evaluating the tritium inventory of ISS facilitates the evaluation of the minimum initial startup tritium inventory for the operation of the fusion reactor. The chemical simulation software Aspen Plus is used to simulate the separation process of ISS. The purity of products and the distribution of hydrogen isotopes in each distillation column are obtained. Based on the simulated data, the tritium inventory in each distillation column is calculated.

FORMATION CONDITIONS OF GROUNDWATER OF THE UPPER JURASSIC OF THE CENTRAL REGIONS OF THE ZAURAL MEGAMONOCLYSIS

The article presents the first results of complex isotope-hydrogeochemical studies of reservoir waters of the Upper Jurassic deposits of the central regions of the Zaural megamonoclysis. It was shown that most waters have a narrow distribution of oxygen and hydrogen isotopes (δD from -103.2 to -85.6 ‰ and δO from -15.4 to -12.9 ‰). Some of them have pronounced excursions on the isotopic composition, which indicates a difference in their genesis: from condensate to mixed with ancient infiltrogenic. The isotopic composition of carbon of water-dissolved carbon dioxide (δС from -41.6 to -16.3 ‰) indicates its biogenic origin and the possibility of interstratal flows from overlying horizons.

Distribution of hydrogen and oxygen stable isotopes and pollution indicators in water during a monsoon transitional period in Min River Basin

Based on 197 monthly river water and groundwater samples and 30 event-scale precipitation samples, our study reports the distribution of hydrogen and oxygen isotopes and pollution indicators in Min River Basin. The variation of δ18O and d-excess indicate that the water source in the upper main course water is more variable and that in the middle-lower part is relatively stable. Comparison between plots of δ2H versus δ18O in the river water and precipitation reflect the dominant water source is different between river water in the upper and middle-lower parts. The electrical conductivity (EC) shows a similar spatial variation trend for main course water collected in four campaigns. The pollutant concentration change at the confluences of main tributaries shows that the inflow of Heishui River and Dadu River leads to decreased NO3− and Cl−, while that of Xi River, Pu River and Fuhe River leads to a leap in NO3− and Cl−. A significant positive correlation is observed between EC and δ18O, indicating the consistent control of water sources on isotope distribution and water quality. The relationship between elevation and δ18O in the main course river water suggests that the factors affecting isotope distribution vary spatially. “Altitude effect” can only be observed in October and November for the upper steepest plateau zone due to the spatial variation in the precipitation stored during the wet season. The “inverse altitude effect” is observed for the upper part during the wet season and for the middle-lower part during the whole study period, which can be explained by the contribution of tributaries with different discharge regimes. Our findings show that water source with different discharge regimes can serve as the leading factor controlling the stream component in multi-tributary river basins with large spatial span and may mask the influence of spatial distribution of precipitation.

Revealing the impact of water conservancy projects and urbanization on hydrological cycle based on the distribution of hydrogen and oxygen isotopes in water.

In recent years, the development and utilization of water resources have imposed great impacts on hydrological characteristics and ecological environment. In this paper, methods based on stable isotopes were used to analyze the cumulative effect of water projects and urbanization on the hydrological cycle in Qingbaijiang River Basin. Isotope evidence shows that the hydrological processes affected by water regulation and urbanized runoff generation differentiate greatly from the natural state. The annual mean isotopic values follow an order of groundwater > rainwater > river water. Consistent isotopic composition and variation trend between the near-bank groundwater and river water were only observed from May to late June 2018 and from February to April 2019 in the upper zone, indicating the dominant recharge of river to the groundwater. However, the isotopic variations between the two waters in the middle and lower zones suggested that the hydraulic exchange was limited, demonstrating the significant changes in river water level caused by the reservoir impoundment. The isotopic enrichment rate along the flow path is highest in January (0.0265‰/km), followed by October (0.0160‰/km), indicating the significant evaporation, while slight spatial changes in July (0.0027‰/km) reflected masked evaporation effect. This variability can be mainly attributed to the flow rate change and increase of water salinity in anthropic zones. Periodic regression analysis was employed to evaluate the difference in rainfall-runoff responses between hydrographic zones and estimate the mean residence time (MRT). Periodicity of isotopes in river water increased from upper to lower reaches with increasing R2 values from 0.04 in SW1 to 0.46 in SW8. The MRT grew shorter along the flow path from 870days in SW1 to 293days in SW8, reflecting accelerated rainfall-runoff process due to the increasing impervious surface area and drainage system. These results identify the sensitivity of stable isotopes to the land use changes, runoff generation, and topography, and have implication for the potential water and environmental risks. Based on these understandings, suggestions for sustainable water-environment management in urban and rural areas were proposed.

Position-specific distribution of hydrogen isotopes in natural propane: Effects of thermal cracking, equilibration and biodegradation

Intramolecular isotope distributions, including isotope clumping and position specific fractionation, can provide proxies for the formation temperature and formation and destruction pathways of molecules. In this study, we explore the position-specific hydrogen isotope distribution in propane. We analyzed propane samples from 10 different petroleum systems with high-resolution molecular mass spectrometry. Our results show that the hydrogen isotope fractionation between central and terminal positions of natural propanes ranges from −102‰ to +205‰, a much larger range than that expected for thermodynamic equilibrium at their source and reservoir temperatures (36–63‰). Based on these findings, we propose that the hydrogen isotope structure of catagenic propane is largely controlled by irreversible processes, expressing kinetic isotope effects (KIEs). Kinetic control on hydrogen isotope composition of the products of thermal cracking is supported by a hydrous pyrolysis experiment using the Woodford Shale as substrate, in which we observed isotopic disequilibrium in the early stage of pyrolysis. We make a more general prediction of KIE signatures associated with kerogen cracking by simulating this chemistry in a kinetic Monte Carlo model for different types of kerogens. In contrast, unconventional shale fluids or hot conventional reservoirs contain propane with an isotopic structure close to equilibrium, presumably reflecting internal and/or heterogeneous exchange during high temperature storage (ca. 100–150 °C). In relatively cold (<100 °C) conventional gas accumulations, propane can discharge from its source to a colder reservoir, rapidly enough to preserve disequilibrium signatures even if the source rock thermal maturity is high. These findings imply that long times at elevated temperatures are required to equilibrate the hydrogen isotopic structure of propane in natural gas host rocks and reservoirs. We further defined the kinetics of propane equilibration through hydrogen isotope exchange experiments under hydrous conditions; these experiments show that hydrogen in propane is exchangeable over laboratory timescales when exposed to clay minerals such as kaolinite. This implies rather rapid transfer of propane from sources to cold reservoirs in some of the conventional petroleum systems. Propane is also susceptible to microbial degradation in both oxic and anoxic environments. Biodegradation of propane in the Hadrian and Diana Hoover oil fields (Gulf of Mexico) results in strong increases in central-terminal hydrogen isotope fractionation. This reflects preferential attack on the central position, consistent with previous studies.

Time-of-flight secondary ion mass spectrometry study of zinc carbonation in the presence of stable oxygen-18 and deuterium isotopes

Zinc foil was carbonated in supercritical CO2 in the presence of water containing stable 18O or deuterium isotopes. The carbonation resulted in precipitation of zinc carbonate crystals with hexagonal and cubic morphologies until the source of hydroxyl groups was depleted. Time-of-flight secondary ion mass spectrometry was utilized to map the isotopes in the precipitates. The isotopes were detected in the precipitated structures, which confirms the formation of carbonic acid as the initial corrosion procedure step, followed by zinc dissolution. This finally leads to the arrangement of zinc ions with carbonate ions, and storage of OH-groups between ZnCO3 layers as Zn(OH)2 or molecular water. The results completed chemical composition data obtained with molecular spectroscopy. Mapping of the distribution of hydrogen and oxygen isotopes by ToF-SIMS provided essential information on the reaction routes of carbonation in a humid scCO2 environment.

Visualization of hydrogen isotope distribution in yttrium and cobalt doped barium zirconates

Tritium (T) distributions in yttrium (Y) and cobalt (Co) doped barium-zirconates (BaZrO3) were visualized by imaging plate (IP) technique using HT gas (T/H = 10−4, ∼1.3 kPa) under various exposure temperatures (623 to 1273 K) and exposure times (5 min to 16 h). Two types of specimens, BaZr0.9Y0.1O3-α (BZY) and BaZr0.955Y0.03Co0.015O3-α (BZYC), were prepared with conventional powder metallurgy: disk-shaped specimens were obtained with more than 97% of the theoretical densities. With IP method, uniform tritium distribution was found on the surface of both T-exposed specimens. The T distributions of the cross sections of the cut-in-half specimens were also examined with IP, which showed that more T was diffused into BZYC compared to BZY. The diffusivities of T and hydrogen solubility were determined by the T concentration profiles for the BZY and BZYC samples at different exposure conditions. Almost one order higher solubility and diffusivity for BZYC than BZY was found. It suggests that only a small amount sintering-aid cobalt doping along with yttrium may play a vital role of enhancement of electrochemical activity of the proton conducting BaZrO3 under HT exposure condition.

Analysis of the Spatial Distribution of Stable Oxygen and Hydrogen Isotopes in Precipitation across the Iberian Peninsula

The isotopic composition of precipitation provides insight into the origin of water vapor, and the conditions attained during condensation and precipitation. Thus, the spatial variation of oxygen and hydrogen stable isotope composition (δp) and d-excess of precipitation was explored across the Iberian Peninsula for October 2002–September 2003 with 24 monitoring stations of the Global Network of Isotopes in Precipitation (GNIP), and for October 2004–June 2006, in which 13 GNIP stations were merged with 21 monitoring stations from a regional network in NW Iberia. Spatial autocorrelation structure of monthly and amount weighted seasonal/annual mean δp values was modelled, and two isoscapes were derived for stable oxygen and hydrogen isotopes in precipitation with regression kriging. Only using the GNIP sampling network, no spatial autocorrelation structure of δp could have been determined due to the scarcity of the network. However, in the case of the merged GNIP and NW dataset, for δp a spatial sampling range of ~450 km in planar distance (corresponding to ~340 km in geodetic distance) was determined. The range of δp, which also broadly corresponds to the range of the d-excess, probably refers to the spatially variable moisture contribution of the western, Atlantic-dominated, and eastern, Mediterranean-dominated domain of the Iberian Peninsula. The estimation error of the presented Iberian precipitation isoscapes, both for oxygen and hydrogen, is smaller than the ones that were reported for the regional subset of one of the most widely used global model, suggesting that the current regional model provides a higher predictive power.

Distribution of Hydrogen Isotopes between Phases at Vapor–Liquid Equilibrium in Aqueous Salt Solutions

A single separation effect between deuterium and protium was studied experimentally under phase equilibrium conditions in a water vapor–water salt solution system at temperatures from 59 to 94°C. The vapor–liquid equilibrium was investigated by the dynamic method in a Bushmakin device. The presence of urea in water significantly increased the separation coefficient αL–V in the given temperature range. The characteristic increase in the relative volatility coefficient of the hydrogen isotopes of water remained unchanged at lower temperatures in the presence of salts. The isotope salt effects, both negative and positive, increased with the salt concentration.

Molecular and isotopic behavior of insoluble organic matter of the Orgueil meteorite upon heating

Organic matter contained in carbonaceous chondrites may have evolved due to aqueous and/or thermal evolution on the parent body. The thermal behavior of the insoluble organic matter (IOM) of the Orgueil meteorite was investigated. The evolutions of structural and molecular properties were assessed by Raman, infrared and XANES spectroscopies, the H- and N-isotopic compositions by NanoSIMS. The starting IOM is a disordered organic macromolecule presenting a high degree of cross-linking. Hydrogen and Nitrogen isotope distributions are heterogeneous with the occurrence of numerous micron-sized hot spots enriched in heavy isotopes of H or N. After 1 hour at 300°C, there is subtle modification of the structural ordering and the isotopic compositions. After 1 hour at 500°C, the structure evolves toward condensation. Indeed, FTIR and XANES data are consistent with a continuous evolution of the molecular structure toward an increase of aromatization, starting at 300°C and becoming more intense at 500°C. The bulk D-enrichment is significantly reduced and D-rich hot spots are lost at 500°C. The experimental evolution of the δD is consistent with observations of IOM isolated from lightly altered carbonaceous chondrites. In contrast, the 15N-rich hot spots seem insensitive to high temperature up to 500°C and bulk δ15N remains constant. The thermal evolution of H- and N- isotopes is decoupled, indicating that the D-rich and 15N-rich moieties exhibit different thermal recalcitrance.

New isotope-hydrogeochemical data on the Bang spring (Kuang Binh province, central Vietnam)

New isotope hydrogeochemical data on two types of thermal water from the Bang spring (Kuang Binh province, central Vietnam) are reported in the work. The first type includes HCO3–Cl–Na–Mg water with extremely low mineralization (44–87 mg/dm3) and pH variations from weakly acidic to weakly alkaline values (5.71–7.84). The second type includes HCO3–Na water with mineralization up to 256–659 mg/dm3 and pH 8.03 to 8.51. The studied types differ significantly in temperature: 24.3–34.5°C in the first type and 62.1–97.1°C in the second type. The analysis of the distribution of oxygen (δ18O) and hydrogen (δD) isotopes carried out for the first time confirms different genetic nature of these hydrogeochemical water types. The first type has an atmospheric genesis (δ18O = –7.3…–6.2‰ and δD = –51.4…–39.3‰), while the second type restricted to the Kien Giang–Bang intersection zone has a deeper source (δ18O = –1.6…–1.3‰ and δD = –22.2…–21.4‰). The tritium (3H) data also point to different circulation times of these waters. The formation time of the HCO3–Cl–Na–Mg waters does not exceed 50 years (3H = 4.3–11.1 ТЕ), while that of HCO3–Na water may reach more than 1000 years (3H = 0.5 ТЕ).

Influence of hydrous pyrolysis on distribution of carbon and hydrogen isotopes by organic matter fractions. The nature of oil generation in the calder of Uzone Volcano in Kamchatka

The process of oil seeps transformation from the Uzon volcano caldera under the influence of hydrous pyrolysis at a temperature of 350 °C in argon and oxygen was investigated. It is shown that carbon and hydrogen isotope type curves (ITC) reflect the processes occurring in organic matter during hydrous pyrolysis in oxidizing and neutral media. The similarity in forms between carbon ITC of the Uzon oil seeps, the Bogachevka oil and biota of hydrothermal sources is revealed. Hydrogen ITCs have a more complex form, apparently associated with exchange processes occurring in hydrothermal water. Based on the conducted studies, it was assumed that on the one hand oil seeps in the Uzon caldera can serve as a source for the formation of Bogachevka oil, and on the other hand, it is possible that the circulating hydrothermal water in the caldera of the Uzon volcano brings to the surface the organic matter of the Bogachevka oil formation.

Effect of Hydrous Pyrolysis on the Distribution of Carbon and Hydrogen Isotopes between Fractions of Organic Matter. The Nature of Oil Seeps in the Uzon Caldera, Kamchatka, Russia

The paper presents data on the transformations of oil from seeps in the caldera of Uzon volcano under the effect of hydrous pyrolysis at a temperature of 350°C in an argon and oxygen atmosphere. The carbon and hydrogen isotopic-fractionation characteristics (IFC) are proved to reflect processes occurring in the organic matter at its hydrous pyrolysis in oxidizing and neutral environments. Similarities in configuration are detected between the carbon IFC of Uzon oil seeps, Bogachevskoe field, and the biota of hydrothermal springs. The hydrogen IFC are of more complicated form, perhaps, because of exchange processes in the hydrothermal water. It is hypothesized that oil seeps in the interiors of the Uzon caldera can provide material for the origin of oil at the Bogachevskoe field. At the same time, it cannot be ruled out that hydrothermal water circulating in the caldera of Uzon volcano brings the material of the Bogachevskoe oil to the surface.

Distribution of Heavy Hydrogen and Oxygen Isotopes in Water Distillation

The possibility of high-precision determination of mass transfer characteristics of stainless steel packings in the separation of hydrogen and oxygen isotopes by vacuum distillation of water in columns with a diameter of 60–250 mm was shown. An algorithm for calculating the parameters of separation and the concentration profile of deuterium and oxygen-18 during their simultaneous separation in a closed type unit with product selection by vacuum distillation of water was presented.