Content and Isotope Ratios of Noble Gases in Congelation Ice of Lake Vostok

Isotope ratios of noble gases (He, Ne, Ar) were studied in samples collected by degassing of cores of water frozen over a glacier of Lake Vostok. The gases were collected into glass retorts during three days of degassing of cores, which have just been extracted from the borehole. Within the error, the isotope ³He/⁴He ratios of 0.28 ± 0.08 R_A (R_A = 1.38 × 10^–6 is the ratio for air) correspond to those from [1]. The ⁴He/²⁰Ne and ⁴⁰Ar/³⁶Ar ratios (12.4 ± 4.6 R_A and 1.0074 ± 0.0023 R_A, respectively) exceed their contents in air (⁴He/²⁰Ne_A = 0.29; ⁴⁰Ar/³⁶Ar_A = 298.6) and may indicate some contribution of terrigenous gas to the gaseous balance of the lake, as well as the high content of ancient ground waters in the lake. The ³He/⁴He ratio of 0.28 R_A means low mantle ³He flux typical of continental platforms far from active rift zones.     

Sulfur and Oxygen Isotope Geochemistry of Acid Mine Drainage—The Polymetallic Sulfide Deposit “Himmelfahrt Fundgrube” in Freiberg (Germany)

Abstract

We investigated physical, chemical and isotope (S, O) parameters of sulfate from acid mine drainage from the polymetallic sulfide ore deposit Freiberg (Germany), which was mined for more than eight hundred years. Two main groups of water were distinguished:

1. Flowing mine water with sulfate concentrations of less than 9000 mg/1 and pH values higher than 3.2

2. Pore water in weathered low grade ores and pools with sulfate concentrations higher than 9000 mg/1 and pH values below 3.2.

The sulfur and oxygen isotope composition of sulfate from flowing mine waters reflects mixing of sulfate from two sulfur sources: a) atmospheric sulfur from precipitation and b) sulfate formed as a result of sulfide oxidation processes. Sulfur isotope values of mine water sulfate were used to estimate the contribution of sulfate derived through oxidation of sulfides. The sulfur isotope composition of pore water sulfate and precipitated sulfate (jarosite) from weathered low grade ore samples is identical to the sulfur isotope composition of primary sulfides. The oxygen isotope composition of pore water sulfate from low grade ore samples indicates that the oxidation process proceeds relatively slowly in O₂-depleted waters, probably without significant microbial catalysis.     

Sulfur Isotopic Composition of H2S and SO4 2− from Mineral Springs in the Polish Carpathians

Abstract

A number of springs in Carpathian Mts. contain dissolved H₂S and SO₄ ^2- in concentrations above 10 mg/dm³. In this study we have investigated the sulfur isotope composition (δ³⁴S) of the dissolved sulfur species in the springs from the flysch area in the Carpathian Mts. along the tectonic dislocation. It is believed that some of these springs may carry a major fraction of dissolved sulfur species of extremely deep sulfur (of mantle origin), which is subjected to SO₄ ^2-—H₂S isotope exchange at high temperatures. The original isotopic compositions may be modified by reduction/oxidation at low temperatures and by admixture of sulfur from other sources.

In order to distinguish the sulfur of mantle origin we investigated δ³⁴S of dissolved sulfide and sulfate and on the basis of known concentrations we calculated δ³⁴S of total dissolved sulfur. The isotope fractionation between sulfate and sulfide helped to distinguish the sulfur origin. Evaluating the sulfur isotope exchange, we selected 4 springs which likely have only weakly disturbed sulfur of mantle origin.     

35MeV/u40Ar+197Au中的熵产生

根据量子统计模型(QSM)的计算分析,找到了一个提取核反应过程中熵产生的新的可观测量.核反应过程中约化d的产额d/(d+t+³He+⁴He)和熵有单调的函数关系,并且和体系的碎裂密度(ρ/ρ₀)及体系的N/Z都无关,可以作为提取核反应过程中熵产生的一个观测量.和目前已经有的其他方法相比,约化d产额这一提取熵方法可以用于较低能量的重离子核反应中,并且数据处理分析简单.对于35MeV/u⁴⁰Ar+¹⁹⁷Au的核反应过程所提取的熵和利用约化带电粒子多重性提取的熵结果一致.结合后角类靶热核发射体系实验提取的同位素核温度为4.7±1.2MeV及S/A=2.5±0.5,根据熵和核温度的关联关系,可以确定其Break up密度接近但小于0.1(ρ/ρ₀) 关键词： 熵 约化d产额 核温度 统计发射     

PreCon: A Fully Automated Interface for the Pre-Gc Concentration of Trace Gases on Air for Isotopic Analysis

Abstract

For the high precision isotope analysis of atmospheric trace gases a computer controlled concentration interface has been developed. From small air samples it collects either N₂O or CO₂ derived from CH₄ at their respective concentrations (0.3 ppm for N₂O, 1.7 ppm for CH₄) into a small diameter cold trap (?196°C) and interfaces via GC and open split to an isotope ratio mass spectrometer (Finnigan MAT 252) for on-line isotope evaluation. External reproducibilities for repeated measurements of 100 ml air samples from the same source of < 0.2° (δ-notation) have been achieved for ¹³C/¹²C from CH₄ and for ¹⁵N/¹⁴N and ¹⁸O/¹⁶O from N₂O. The precision is adequate to monitor the isotopic changes in these gases during a day's course.     

Sulphur and Oxygen Isotopes in Sulphates in Natural Waters: (2) Deep-Waters from Horizons Below Baltic Sea Floor

Abstract

In this paper we consider deep waters from horizons located under the Baltic-Sea bottom. The samples were taken twice from wells bored in Hel peninsula. The δ¹⁸O and δD values of these waters show their glacial origin since they have significantly low values (δ¹⁸O from ?14 to ?11 whereas the modern groundwaters in Gdańsk area have ?10%₀). In contrast to surface waters the sulphates dissolved in these deep waters have rather high and uniform δ¹⁸O values which are correlated with δ¹⁸O of H₂O but not correlated with δ³⁴S. The isotope patterns may be explained assuming that the waters are very old, in which the slow process of oxygen isotope exchange at low temperatures, but extended in time, could enrich the sulphate in heavier oxygen isotopes.     

The Inverse Problem of Argon Diffusion from Minerals: Determination of Kinetic Parameters from Stepwise-Heating Experiments

Abstract

Results of two routine ⁴⁰Ar/³⁹Ar stepwise heating experiments on a biotite and a basanite are interpreted in terms of Fick's and Arrhenius' laws. Both patterns represent a saddle-shaped ³⁹Ar release. Argon isotope spectra are suggested to be controlled by the activation energy of diffusion E and the frequency factor D_o . The activation energy of ³⁹Ar is lower than the one of ⁴⁰Ar. This results in a preferable release of ⁴⁰Ar relatively to ³⁹Ar at high-temperature steps and an increasing high-temperature wing in the saddle-shaped age spectrum. At low temperatures, considerable losses and irregularities in release of mainly ³⁹Ar are observed, which cause the decreasing low-temperature wing in the “saddle”. The suggestion of argon losses (mainly of ³⁹Ar) from a loose, “unstable” zone of the mineral structures becomes justified. The n-irradiation of the samples and the shift of E of ³⁹Ar towards lower values seems to explain the saddle-shaped age-spectra often encountered in ⁴⁰Ar/³⁹Ar-geochronometry.     

Evaluation of the Sulfate Dynamics in Groundwater by Means of Environmental Isotopes

Abstract

Elevated sulfate concentrations and their heterogeneous distribution in the drinking water catchment area Torgau-Mockritz (Germany) were investigated by means of multiple isotope signatures such as δ³⁴S, δ¹⁸O-H₂O, δD, tritium, and ⁸⁵Kr. δ³⁴S values of the groundwater sulfate vary between -19…+ 37‰ CDT. No simple correlation exists between sulfate concentrations and δ³⁴S. Superimposition of different sulfur sources and mobilization processes combined with a complicated groundwater movement create a complex distribution pattern. The oxidation of reduced sedimentary sulfur has to be regarded as a main source of dissolved sulfate at least regionally. Tritium and ¹⁴C data revealed that old groundwater can be excluded as source for high sulfate contents. Correlated temporal variations in the concentrations of tritium and sulfate are observed in deeper sampling positions. Highly variable δ¹⁸O and δD, as detected in parts of the catchment area, indicate local influences of surface water infiltration into the aquifer. The spatial distribution of isotope signatures enables the identification of zones with descending younger water or hindered groundwater movement and hence provides useful hints for flow modeling.     

A gas flow proportional counter for the Mössbauer study of surfaces between 100 K and 400 K

A gas flow proportional counter has been constructed for operation between 100K and 400K without the need for an evacuated cryostat. The detector is temperature controlled and may be used for detecting conversion electrons or X-rays. Six different gases, pure He, He/1%CH₄, He/5%CH₄, He/10%CH₄, He/5%Co, and Ar/5%CH₄ have been investigated in order to obtain maximum efficiency and reliability of operation. At room temperature and above, all gases are suitable. At low temperatures, He/5%Co is the most suitable for electron detection, For X-ray detection, Ar/5%CH₄ is suitable over the entire temperature range.     

Fractionation of Carbon Isotopes During Carbohydrate Fermentation in Ruminants

Abstract

In the forestomaches of ruminants the carbohydrates of the diet are transformed by microbiotic fermentation via pyruvate into short chain-fatty acids (acetate, propionate, and with less quantity butyrate). Since carbohydrates, i.e. glucose, cannot penetrate the rumen epithelium, metabolically needed glucose must be resynthesized intermediary mainly from propionate by gluconeogenesis.

Lactose in milk of lactating cows is formed up to 98% from glucose of that origin [1]. Glucose absorption is possible in the small intestine, but contrary to monogastric animals, this is without quantitative relevance.

Therefore, an experimentally found higher abundance of ¹³C in lactose of about 3‰, compared with milk-fat [2], is not explainable only by passing on the well known isotopic differences between carbohydrates and fat in the diet. According to the conclusion of De NIRO and EPSTEIN [3], who identified the decarboxylation of pyruvate to be the relevant step of ¹³C depletion in fat in cultures of Escheria coli, we assume an isotopic shift between propionate and acetate produced by the ruminal microorganisms using pyruvate as the last common precursor of both fatty acids.

In vitro-investigation of ¹³C/¹²C - ratios in CO₂ produced during the decarboxylation of pyruvate in fresh rumen-fluid, confirmed the responsibility of that enzyme-reaction for isotope fractionation also in the multiple-step-system of ruminal carbohydrate conversion.     

Effects of laser pulsewidth on higher-order harmonic generation in the barrier-suppression-ionization intensity regime

We studied the highest harmonic photon energies of high-order harmonic generation (HHG) for He, Ne, Ar, Kr, Xe, and N₂. This research employed 65-fs and 150-fs Ti:sapphire laser pulses, of which the peak intensities in a vacuum are higher than the barrier-suppression-ionization (BSI) intensities. We fitted two analytical formulae to the experimental results of HHG. One formula, which was obtained by fitting an analytical formula to the results by a quantum mechanical simulation of HHG, expresses the highest interaction intensity by a function of the BSI intensity and the Keldysh γ-parameter. The other formula is derived by introducing the saturation intensity of HHG, which was proposed by Chang et al. [Phys. Rev. Lett. 79, 2967 (1997)]. We discuss the highest interaction intensity for the condition when the peak laser intensities are higher than the BSI intensities. Received: 19 March 1999 / Revised version: 13 August 1999 / Published online: 27 October 1999     

New Information About Natural Gases of Alkaline Massifs

Abstract

The use of gas-geochemical study results for decisions of various problems of mining and geological character was shown by example of the alkaline nepheline syenite massifs in the eastern part of Baltic Shield. Two principal morphologic types of gases (freely evolved and occiuded or microincluded) are known in the considered rocks. The gas composition is: hydrogen-hydrocarbons, mixed with He, N₂, sometimes CO, and CO₂. Discovering gas zoning, relative time of generation and space distribution regularities of gases concerning ore deposits assume the participation of reduced fluids and postmagmatic processes in the formation of certain ores, the origin of which was considered magmatic. In some cases gas-geochemical peculiarities of rock and minerals can be employed in the capacity of indicators of ore mineralization in search works. However studies of gases (compositions, distribution, release conditions and intensity) have most practical significance for guarantee of ore deposits gas-safe exploitation. It is suggested to use the detected relationships of gas-geochemical, gas-dynamic and tectonophysic parameters for the evaluation of rock stress level and forecasting of mining shocks.     

Variations of Lead Isotopes and Airborne Particulate Concentrations From the Kozani Basin,West Macedonia,Greece

Abstract

The spread and variation in ²⁰⁶Pb/²⁰⁷Pb ratios make Pb isotopes a powerful tool when it comes to detecting trends in airborne particulates originating mainly from power plants. This study was conducted to determine the source of pollution in Kozani area, an affected industrial area. Lead isotopic ratios of air filters under certain meteorological conditions were compared to Pb isotope analyses sampled from lignite mines, but also to Pb isotope analyses of cultivations in soil originating from the reclamation of old abandoned lignite-mines. The particles taken into consideration have an aerodynamic diameter less than 10 μm (PM10). The measurements were carried out in a central part of the town of Kozani, West Macedonia, for one year observation period. The lead isotope values of air filters and of wheat in the Kozani area are between the values of lignite Pb and of Greek gasoline.     

Oxygen and Carbon Isotope Variations of Carbonates and Silicates from the Carbonatite Massif Tiksheozero (Northern Karelia)

Abstract

Carbon and oxygen isotope compositions have been determined for carbonate minerals from different types of carbonatites (large carbonatite bodies, veins, eruptive breccia), as well as from different temperature classes of carbonatites (according to Samoilov [1]). It could be shown, that only high temperature carbonatites exhibit small variations of δ¹⁸O and δ¹³C falling in the range of “high temperature mantle carbonates”, whereas low temperature calcites and dolomites show wide variations in δ¹⁸O. These changes in both isotope and mineral compositions of low temperature carbonatites are interpreted as a result of repeated interaction with fluids. The oxygen isotope ratios in most of the eruptive breccia have been changed by secondary processes. The primary deep-seated isotope record has been preserved only in samples, in which carbonate occurs as fine-grained calcite groundmass.

Preliminary results on oxygen isotope composition of different silicate minerals (amphibole, magnetite, biotite, albite, apatite) indicate isotope equilibrium for the mineral pair calcite-amphibole with isotope temperatures representing superimposed processes.     

Lead and strontium isotopes as indicators for mixing processes of waters in the former mine ‘Himmelfahrt Fundgrube’, Freiberg (Germany)†

To pinpoint the origin and mixing processes of mine waters, different mine water types from the polymetallic sulphide ore deposit ‘Himmelfahrt Fundgrube’ (Freiberg, Germany) were analysed by thermal ionisation mass spectrometry using lead and strontium isotope ratios.

Results show that the lead isotope composition of different mine waters results from a mixture of at least two sources: released lead from oxidised sulphide ores (mainly galena) and anthropogenic lead from groundwater. Furthermore, there are indications for an additional lead source. Strontium isotopes in mine waters identify at least three different sources: released strontium from weathered host rock (Grey Gneisses), released strontium from weathered gangue carbonates, and probably strontium from anthropogenic inputs. Contrary to former oxygen and sulphur isotope studies, strontium isotope compositions as well as hydrochemical parameters show the important role of gangue carbonates as an element source in mine waters.     

Informationsmöglichkeiten Des Radons in Unterirdischen Wässern

Abstract

The paper deals with the correlation between the Rn-concentration in underground waters and the Ra-concentration in these waters, but also the correlation between Rn-concentration in these waters and Rn-concentrations of gases in rocks around these waters. Essential for the Rn-concentration is the Ra-concentration only in such water which has an extraordinarily high Ra-concentration.

It is mentioned that ²¹⁰Pb-activity is not in balance with the Rn-activity. Solid surfaces absorb this isotope. This absorption was proved by experiments: A sample was kept in a closed bottle for eleven years, and then the concentration of ²¹⁰Pb in this water-sample was measured. Also ²¹⁰Pb and its “daughter-atoms” were searched for on the inside of the bottle. Also measurements of the Rn-concentration and other parameters were carried out in mineral springs near the river Tschicherte. The results will influence the decision, whether a health-resort will be built in this region or not.     

Isotope-Ratio-Monitoring Liquid Chromatography Mass Spectrometry (IRM-LCMS): First Results from a Moving Wire Interface System

Abstract

A Liquid Chromatography-Combustion (LC-C) Interface, based on a moving wire technique, has been built and tested. The LC effluent is deposited onto a transport wire, which carries the sample through solvent evaporation and combustion ovens. CO₂ from the combustion step is analysed in an isotope ratio mass spectrometer. Performance of the interface was tested by loop injections of sucrose and glucose into a liquid flow of methanol/water (80/20). Accuracy and precision of δ¹³C_PDB < 1‰ was achieved for sample concentrations > 500 ng/ul (5μl loop), sufficient for studies at natural isotope ratios. In case of ¹³C tracer applications the detection limit was determined to be about 20 pg carbon tracer (on wire).     

Distribution of the isotopes produced in the YBa2Cu3O7−x superconductor and PbZr0.54Ti0.46O3 ferroelectric by energetic charged particles

A study has been made of the concentration profiles of radioactive isotopes produced by transmutation in the YBa₂Cu₃O_7−x superconductor and PbZr_0.54Ti_0.46O₃ ferroelectric by energetic protons (10 and 15 MeV), deuterons (4 MeV), and ³He and ⁴He nuclei (20 MeV). Profiles of two types have been observed: monotonic and with a maximum. It is shown that the type of isotope concentration profile is determined by the nature of the cross-section energy dependence of the nuclear reaction producing a given isotope. Fiz. Tverd. Tela (St. Petersburg) 40, 2189–2191 (December 1998)     

PB- Und Sr-Isotopensignaturen AlS Herkunftsindikatoren Für Anthropogene Und Geogene Kontaminationen

Abstract

In isotope geochemistry, natural differences in isotope abundance ratios of heavy elements (e.g. Sr, Nd, Pb) allow the use of specific isotopic signatures as tracers for these and genetically related elements. Examples of such applications in the field of anthropogeochemistry will be presented for lead and strontium.     

Isotope Ratios of Light Charged Particles and Temperature in the Reactions 30MeV/u40Ar+112,124Sn

Coincidence measurements between residues and light charged particles (LCPs) have been made for the reactions 30MeV/u 40Ar+^112,124Sn. The LCPs were measured by 11 semi-conduct telescopes from very forward angle to backward angle. The times of flight of the residues were measured by PPACs installed concentrically around the beam at forward angle. The excitation energy of the primary hot nuclei was obtained from the velocity of residues in the frame of incomplete fusion model. The single isotope ratios, as function of observing angle and excitation energy have been studied. The ratio of ³He/⁴He and ⁶Li/⁷Li increases with angle while that of ⁶He/⁴He and ⁸Li/⁷Li decreases. The calculation of statistical theory can not reproduce the curve quantitatively, implying the existence of dynamic effect. Isospin effect of the primary hot nuclei on the single isotopic ratios is demonstrated. However, the temperature extracted from double isotope ratios is target independent.