Determination Of Isotopes Research Articles

Status report on AMS measurements of plutonium isotopes using the 1MV Tandetron Accelerator at IFIN-HH

Accelerator Mass Spectrometry is the most sensitive measurement method that allows us to determine 239, 240, and 244Pu radioisotopes in environmental samples with extremely low isotopic concentrations. By measuring plutonium isotopes, we focus our research activity on two main directions, monitoring of environmental nuclear pollution and nuclear astrophysics.This report gives an overview of the progress that was made in the determination of plutonium isotopes at IFIN-HH, and it starts with the studies performed for the transport and measurement of actinides using the 1MV Tandetron Accelerator. The 238U and 232Th isotopes were used as pilot beams for the determination of ion transport parameters, after which the isotopic ratios 239Pu/242Pu, 240Pu/242Pu, and 244Pu/242Pu were measured using the new Plutonium Standard ColPuS. The results obtained for the isotopic ratios agree with the consensus values of the standard. In addition, we developed radiochemical procedures for thorium, plutonium, and uranium separation, the chemical recoveries of uranium and thorium using UTEVA and TEVA resins are presented, where we used an Agilent ICP-MS system (Inductively Coupled Plasma Mass Spectrometry). The radiochemical separation is important mainly for obtaining target materials that can provide microscopic pilot beams as U and/or Th. Finally, a short overview is provided of the molecular interference challenges that are encountered when measuring plutonium isotopes.

New Potential Sphalerite, Chalcopyrite, Galena and Pyrite Reference Materials for Sulfur Isotope Determination by Laser Ablation‐MC‐ICP‐MS

The sulfur isotope system is important in tracing a variety of geochemical processes. However, the availability of matrix‐matched reference materials for in situ sulfur isotope ratio measurement is limited. This study analysed four sulfide specimens to investigate their potential as reference materials for in situ sulfur isotope determination, including three natural sulfide minerals (sphalerite SPH‐1, chalcopyrite GC‐1 and galena NWU‐GN), and one resin preserved pyrite powder (RPPY). These four sulfides were analysed independently in four laboratories using both bulk and microbeam analysis techniques, all of which gave equivalent results within uncertainty with comparable accuracy and precision. The sulfur isotopes of these four sulfides are homogeneous based on a large number of isotope determinations by solution nebulisation multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS) and laser ablation (LA) MC‐ICP‐MS. The mean δ34S values for SPH‐1, RPPY, GC‐1 and NWU‐GN determined by gas source isotope ratio mass spectrometry (GS‐IRMS) and solution nebulisation MC‐ICP‐MS are −7.13 ± 0.41‰ (2s), 3.66 ± 0.24‰ (2s), −0.65 ± 0.28‰ (2s), 28.21 ± 0.17‰ (2s) relative to the Vienna‐Canyon Diablo troilite (V‐CDT) reference value, respectively, and which are proposed as potential preferred values. Over 400 spot analyses performed on randomly selected fragments of each sulfide by LA‐MC‐ICP‐MS yielded highly consistent δ34S values with the preferred values. Thus, SPH‐1, GC‐1, NWU‐GN and RPPY are considered a set of candidate matrix‐matched sulfide reference materials for in situ sulfur isotope determination.

A rapid method of simultaneous chromatographic purification of Li and Mg for isotopic analyses using MC-ICP-MS

Lithium (Li) and Magnesium (Mg) isotopes have been widely used as valuable tracers to study geological processes. In general, several column separation procedures have been used to separate Li and Mg. In this study, we present an optimized protocol for the rapid and simultaneous purification of Li and Mg, which significantly reduces the separation time, required reagent volume, and procedural blanks compared to previous methods. Samples with small amounts of Li (generally 5 ng Li yielding Mg masses of 1–1200 μg) were separated, with the corresponding yields of Li and Mg being nearly 100%. Lithium and Mg isotope analyses were performed using an MC-ICP-MS (Thermo Scientific NEPTUNE Plus) and only <0.2 ng Li and <150 ng Mg were consumed for each analysis. Matrix-doping experiments reveal that the matrix effect is negligible for the determination of Li and Mg isotopes from a wide array of geological samples using our protocol. The robustness of the protocol has been validated by replicated analyses of standard solutions and geological standards, which yield long-term external 2σ precision better than ±0.6‰ for δ7Li and ±0.08‰ for δ26Mg. Lithium and Mg isotopic ratios of all reference materials measured in this study agreed well with previous data within uncertainties. The method developed in this study allows for the rapid and high-purity separation of Li and Mg and subsequent high-precision isotopic analyses of these elements.

An improved rapid method for the determination of actinides in water

A new rapid method has been developed for the determination of Th, Pu, Np, U, Am and Cm isotopes in water samples of about 1 L. Actinides are pre-concentrated by co-precipitation with Ca phosphate, sequentially separated on stacked TEVA and TK221 cartridges and measured by alpha spectrometry. The TK221 extraction chromatographic resin contains i.e. CMPO and DGA extractants. It has been characterized by measuring the weight distribution ratios (Dw) of actinides which are higher than 1000 for all actinides in 3 M HNO3. The method has been optimized, applied for the analysis of tap and seawater samples and validated by participating in an IAEA proficiency test. Chemical recoveries for all actinides are better than 50%. The method can be performed within one day.

Simultaneous analysis of stable and radiogenic strontium isotopes in reference materials, plants and modern tooth enamel

Radiogenic strontium isotopes (87Sr/86Sr) are a useful tool in forensics, ecology, bioarcheology and paleoanthropology allowing investigation of present and past migration and landscape use. The measurement of the 87Sr/86Sr ratio traditionally assumes a constant stable (88Sr/86Sr) isotope ratio. However, some studies indicate that these stable Sr isotopes may display mass-dependent fractionation, suggesting that the 88Sr/86Sr ratio may fingerprint previously unknown dietary and physiological information. Here we present a survey of the variability of δ88Sr values, along with the 87Sr/86Sr ratios, in fourteen reference materials of geological and biological origin using MC-ICPMS. The measurements employ a simple sample-standard bracketing method and zirconium external correction. Comparisons with double-spiked δ88Sr TIMS analyses show a very good agreement (0.014 ‰; n = 10). We then applied this method to explore the fractionation of the 88Sr/86Sr ratio in tooth enamel of mammals from two modern food-chains (Kruger National Park and Western Cape, South Africa), and from modern South African chacma baboon populations. Clear differences in the δ88Sr values are observed between plants and teeth of herbivores (~ −0.26 ‰; n = 5), but the distinction between herbivores and carnivores requires further investigation. Variations between tooth enamel of young and adult baboons suggests that the δ88Sr is a promising indicator of weaning behaviors. Our method implementation and preliminary results highlight the importance of coupled radiogenic and stable Sr isotope determination in extant and extinct vertebrates.

Petrographic and geochemical characteristics of selected coal seams from the Late Cretaceous-Paleocene Guaduas Formation, Eastern Cordillera Basin, Colombia

Petrographic, geochemical and carbon isotopic determinations were conducted on five samples from four seams within the Late Cretaceous-Paleocene of the Guaduas Formation in Colombia. The individual coal seams are thin, ranging from 0.59 to 1.2 m, and occur over a 157 m interval. The average weighted ash yield is 13.7% (dry basis), although one sample presented values >35%. Vitrinite reflectance increases from 1.33% in the stratigraphically uppermost seam (La Cuarta) to 1.44% in the lower most coal seam (Cisquera), indicating their rank to be medium volatile bituminous.The studied sequence of the Guaduas Formation represents a peat environment influenced by shifting depositional settings, particularly in relation to the proximity of marine/brackish water environments as indicated by Sr/Ba values, sulfur, pyrite, δ13C and the proportion of telinite. A decrease in inertinite indicates that the peat mires were becoming relatively ‘wetter’ stratigraphically upwards. This trend, unlike that of Sr/Ba and telinite, may be driven by climatic shifts rather than only changes in depositional environment.Both trace and rare earth elements, plus yttrium (REY) are related to the inorganic fraction of the coal. All rare earth elements are depleted relative to average worldwide hard coals (for trace elements) and average upper continental crust (for REY) with the notable exception of Li and Sb for the high ash yield sample (the La Cuarta lower coal seam). The abundance of some REY elements (i.e. Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb and Lu) may be more influenced by the presence of illite rather than just the quantity of total ash yield. Based on the relationship between SiO2 and Nb/Y, the provenance of the inorganics changed from a rhyolitic source at the lowest seam (Cisquera) to a dacite source in the middle layer (El Tesoro) to an andesite source in the stratigraphically uppermost seams (La Gemela and La Cuarta).

Quantitative analysis of hydrogen isotopes in hydrogen storage material using laser-induced breakdown spectroscopy

• The scanning-coaxial LIBS system is set up for in-situ measurements in fusion reactors. • Titanium foil with different hydrogen and deuterium contents is prepared and determined. • Hydrogen isotopes are analyzed quantitatively using the internal standard method (ISM) and the calibration free method (CF-LIBS). • The single sample correction calibration free method (SSCCF) is applied to improve the accuracy. The accurate determination of hydrogen isotopes in materials is always a challenge for laser-induced breakdown spectroscopy (LIBS). In this study, the content of hydrogen isotopes in hydrogen storage materials is quantitatively analyzed by LIBS using the internal standard method (ISM) and the calibration-free method (CF-LIBS), respectively. Based on the self-built LIBS system, the concentrations of hydrogen and deuterium in titanium hydride with various stoichiometric ratios are quantitatively analyzed. The local thermodynamic equilibrium (LTE) conditions of the plasma are evaluated by the calculation results of the plasma temperature and density: the plasma temperatures are 16000 ± 1000 K calculated by Boltzmann diagram of titanium, and the plasma electron densities are about 10 22 m −3 calculated by the H α line of spectra. Through integral intensity correction, the correlation coefficient of the calibration curves of hydrogen and deuterium is successfully increased by 3% in the internal standard method; The single sample correction is used in CF-LIBS to improve the accuracy of the measurement of hydrogen isotopes in titanium hydride, and the calibration results demonstrate that the average absolute errors are 8.3% and 3.2% for hydrogen and deuterium. We also compare the calculated contents of hydrogen isotopes in titanium hydride by integral intensity correction internal standard method (IICIS) and single sample correction calibration-free method (SSCCF). The SSCCF increases the accuracy of the hydrogen isotope contents compared with CF-LIBS in the range of 20 to 55 at.%. The results are not as precise as the IICIS but meet the ITER requirements in a way. The results provide a valuable reference for the precise measurement of hydrogen isotope content in materials for applications in hydrogen energy, nuclear energy, and nuclear technology.

Multi-proxy evidence for subduction of the Neoproterozoic Adamastor Ocean and Wilson cycle tectonics in the South Atlantic Brasiliano Orogenic System of Western Gondwana

Field, petrographic, geophysical, geochronological, elemental and isotopic data support the identification of distinct components of a Wilson cycle (rift-drift-subduction-collision-collapse) in the South Atlantic Brasiliano Orogenic System (Mantiqueira Province). The main lines of evidence are: 1) Tonian-Cryogenian ophiolite complexes; 2) Hundreds of Hf-Nd-Sr isotope determinations indicating a temporal trend of juvenile to mixed Tonian-Cryogenian-Ediacaran igneous rocks comprising expanded calc-alkaline, magnesian, metaluminous gabbro-tonalite-granodiorite-granite/basalt-dacite-andesite-rhyolite series, developed in island arcs and in continental-margin (Andean-type) arcs; 3) Cratonic-sourced conglomerate-diamictite-sandstone-pelite-carbonate successions deposited in Tonian-Cryogenian rift-passive margins fringing the paleocontinental borders, covered by orogenic basins with contrasting provenance from the arc systems; 4) Paired negative-positive Bouguer anomalies typical of suture zones with ophiolite-bearing accretionary prisms in the lower plate and arc systems in the upper plate; 5) Paired HP/HTmetamorphic belts associated with Ediacaran suture zones and retro-eclogites associated with Tonian subduction. Proposed intracontinental models for this region, both original and revisited, are based on the visual interpretation of restricted space for an oceanic realm and rely on calculations using presumed spreading and subduction rates. However, those do not account for a number of pre-, syn- and post-collisional modifications of the original paleogeography and for plate configurations over a curved planetary surface, with asynchroneity of extensional, accretionary and collisional events over thousands-of-km long orogenic fronts. Scissor-shaped oceanic basins are the rule rather than the exception, with connection of (i) an aulacogen to (ii) a partially enclosed gulf that is, in turn, connected to (iii) an open ocean with complex subduction systems. This configuration leads, after closure of the oceanic realm, to the gradation found in the South Atlantic Brasiliano Orogenic System, with (i) an inverted rift (Paramirim) connected to (ii) a confined orogen with a pre-collisional continental-margin Andean-type arc (Araçuaí), connected, in turn, to (iii) complex accretionary-collisional orogens (Ribeira and Dom Feliciano) with accreted juvenile pre-collisional island arc terranes. This arrangement characterizes, thus, a prime example of a typical subduction-collision orogenic system. The various lines of evidence from distinct fields coherently indicate a full Wilson Cycle with generation and consumption of the Adamastor oceanic lithosphere, followed by continental collisions, ultimately giving birth to the Gondwana paleocontinent.

Direct isotopic analysis of solid uranium particulates on cotton swipes by microextraction-ICP-MS

Direct isotope ratio analysis of solid uranium particulates on cotton swipes was achieved using a solution-based microextraction technique, coupled to a quadrupole inductively coupled plasma - mass spectrometer (ICP-MS). This microextraction-ICP-MS methodology provides rapid isotopic analysis which could be applicable to nuclear safeguards measurements. Particulates of uranyl nitrate hexahydrate (UO2(NO3)2·6H2O) and uranyl fluoride (UO2F2) ranging from 6 μm to 40 μm in length were transferred to cotton swipes with a particle manipulator. The microextraction probe then delivers a 5% nitric acid (HNO3) solvent onto the swipe surface to extract the uranium species. The extracted sample is then delivered to the ICP-MS for isotopic determination. The majority of uranium signal (∼99% and ∼94% for UO2(NO3)2·6H2O and UO2F2, respectively) was detected in the first 15 s extraction, while subsequent extractions on the same location had low or no U signal, suggesting near complete removal of the solid uranium compounds from the swipe surface. Ten samples (for each of the uranium compounds), were analyzed for their isotopic composition. For UO2(NO3)2·6H2O, the determined isotope ratios resulted in a % relative difference (% RD) from the referenced isotope ratios of 0.97, 1.0, and 7.3% for 234U/238U, 235U/238U, and 236U/238U, respectively. The % RD of the UO2F2 isotope ratios were 1.9 and 0.60% for 234U/238U and 235U/238U, respectively. The preliminary limits of detection were determined to be 0.002, 0.4, and 60 pg for 234U, 235U and 238U, respectively This work demonstrates that microextraction ICP-MS is a rapid and sensitive method that could directly determine uranium isotope ratios of UO2(NO3)2·6H2O and UO2F2 particulates on cotton swipes.

Carbon and oxygen isotope analysis of CO2 trapped in silicate minerals

Knowledge of the carbon and oxygen isotope composition of CO2-rich inclusions in crust- or mantle-derived minerals is crucial for a more quantitative understanding of cycling of volatiles between Earth's deep and surficial reservoirs. In this study, we present a crushing method for analysis of combined carbon and oxygen stable isotope compositions of small (≤ nmole) amounts of CO2 in fluid and melt inclusions. During crushing, the released CO2 was cryo-trapped, and subsequently introduced into a Gas Bench II coupled to a Deltaplus Isotope Ratio Mass Spectrometry (IRMS). Reference standard CO2 introduced in the crusher chamber was analysed to a precision better than ~0.3 and ~ 0.4‰ (1σ) for carbon and oxygen, respectively. Analysis of previously analysed samples validates that the crushing technique can be applied to CO2-rich fluid inclusions in quartz samples as small as 0.2 to 5 mg. CO2 –rich quartz samples were analysed from the UHT-Bakhuis Granulite Belt (Suriname) and Val Nalps (Switzerland) as well as forsterite-rich olivine-hosted melt inclusions from Vulsini volcanic district (Italy). The carbon isotope compositions obtained from the quartz samples allow discrimination between different sources within the crust and mantle. In contrast, the oxygen isotopic signatures of the fluid inclusions containing water appear affected by isotopic exchange between CO2 and H2O in the inclusions, where for the free-water fluid inclusions can reflect the pristine δ18O value. Crushing of olivine grains with CO2 melt-inclusions displayed instantaneous adsorption of the released CO2, which leads to low CO2 yields, and considerable oxygen and carbon isotope fractionation, hampering reliable isotopic determinations. We conclude that the δ13C and δ18O values from CO2-rich inclusions can be used as an indicator of the CO2 source and to evaluate mantle CO2 outgassing and release from storages within Earth's crust. The method presented can be readily applied to determine carbon and oxygen isotopic compositions of CO2 (4.5−10 mol) in small amounts of fluid-inclusion bearing quartz.

Subnanomolar Sensitive Stable Isotopic Determination in CO2 by Tunable Infrared Laser Absorption Spectroscopy.

Oxygen and carbon stable isotope ratios (18O/16O, 13C/12C, and 17O/16O) of CO2 have been crucial in helping us understand Earth and planetary systems. These ratios have also been used in medicine for the noninvasive diagnosis of diseases from exhaled breath and for quantifying biochemical or metabolic reactions and in determining the production area of agricultural products. The current method for measuring the stable isotope ratios of CO2 is primarily gas-source isotope ratio mass spectroscopy (IRMS). Due to the recent demand for isotopic microanalysis of carbonates and organic compounds, the sample size required for isotopic measurements has been reduced to approximately 2 nmol CO2 (equivalent to 0.2 μg CaCO3 and 24 ng carbon) by using high-precision IRMS. We report a novel method using tunable mid-infrared laser direct absorption spectroscopy (TILDAS) for sensitive measurements of 18O/16O and 13C/12C in subnanomolar CO2. This method can accurately measure 18O/16O and 13C/12C in CO2 with a repeatability of less than 0.03‰ (n = 28) in a range of 0.3 nmol (equivalent to 0.03 μg CaCO3 and 3.8 ng carbon) to 30 nmol. This is a sample size 1 order of magnitude smaller than currently available sensitive analytical techniques. In addition, the TILDAS system measures 17O/16O simultaneously with a repeatability of less than 0.06‰ (n = 28). Our method is a major advance in supersensitive CO2 stable isotopic analyses for various fields.

An Improved Cr-EA-IRMS Method for the Effective Determination of the Hydrogen Isotopes in Coal Samples.

Hydrogen isotope analysis of coal is an important tool in the geochemical analysis of coal. The traditional method of hydrogen isotope analysis of coal requires the oxidation of organic matter bound hydrogen in coal to water by an oxidizing agent and then its reduction to hydrogen by a reducing agent. This method is time-consuming and laborious, and makes it difficult to cope with the rapid detection of large numbers of samples. The recent development of continuous flow IRMS systems (CF-IRMS) has solved the problem of inefficient analysis, but does not guarantee the quantitative conversion of organic bound H to H2, resulting in inaccurate measured hydrogen isotope values. In this study, for the hydrogen isotope analysis of coal, an alternative continuous flow system (Cr-EA-IRMS) was used to achieve high precision hydrogen isotope measurements of coal samples by filling a quartz reaction tube with Cr. The results obtained by this method (−121.3 ± 1.1‰) for the reference material (GBW11104) are consistent with those obtained by the conventional method (−121.4 ± 0.6‰). Using this method, hydrogen isotope measurements for a variety of imported coals revealed significant differences in the hydrogen isotopes of coals from different coal producing regions including Russia, South East Asia, and Australia. Therefore, the use of hydrogen isotope testing analysis of coal could be a potential means of tracing the origin of coal.

Determination of Stable Chlorine Isotopes by Isotopic Preparative Chromatography (IPC) with Positive–Thermal Ionization Mass Spectrometry (P-TIMS)

A novel approach to chlorine isotope analysis is presented to overcome many drawbacks of existing methods. Contemporary methods often require several laborious off-line procedures prior to instrumental determination; interfering ions (SO4 2- and NO3 -) in real samples are difficult to completely remove, especially when the concentrations of those ions are equal to that of the Cl- ion. This study was aimed to develop an automatic sample preparation method with chromatographic purity for determination of chlorine isotopes using isotopic preparative chromatography (IPC), which was a modified ion chromatograph and a fraction collector. An AS19 chromatographic column was employed to separate chlorine from interference ions using an eluent, flow rate, and suppressor current of 30 mM NaOH, 1 mL/min, and 70 mA, respectively. After the original solutions introduced into the IPC, eluted pure chlorine in the form of HCl was collected in an automated procedure from the outlet of the detector for 6 to 10 mins. The recoveries of chlorine were more than 95% with the relative standard deviation (RSD) of the separation less than 1.8%. After transforming the HCl into CsCl with a resin and concentration in a super-clean laboratory, the samples were sent to the thermal ionization mass spectrometer. The present method was validated by certified reference materials and real samples. The precision of 37Cl/35Cl ratio value was generally below 0.20 ‰. This method provides a potential approach for the analysis of samples with low chlorine concentrations.

Rapid determination of plutonium isotopes in small samples using single anion exchange separation and ICP-MS/MS measurement in NH3-He mode for sediment dating.

To accurately determine ultra-trace Pu isotopes in small environmental samples, we explored ICP-MS/MS in NH3-He mode, and investigated mechanism of 238U interference removal and measurement sensitivity improvement for plutonium isotopes. The interference of uranium and uranium hydrides was effectively eliminated using 0.4mL/min NH3 as reaction gas by shifting them to U(NHm)n+ and UH(NHm)n+. The overall interference of uranium was reduced to <2.4×10-7, while remaining excellent 239Pu sensitivity (13,900 Mcps/(mg/L)) mainly due to ion focusing effect of Pu by helium gas. On this basis, the purification of plutonium using a single AG1-×4 column was proved to be sufficient for accurate determination of plutonium isotopes by the developed detection method, and the detection limits for the method were estimated to be 0.16fg (0.4 μBq) for 239Pu, 0.046fg (0.4 μBq) for 240Pu and 0.039fg (0.15mBq) for 241Pu. The method was validated by analyzing plutonium isotopes in certificated reference materials and reported environmental samples of only 1-2g. The analytical results of ultra-trace Pu isotopes in small amounts (∼1g) of lake sediments obtained by the developed method were successfully applied to sediment dating.

Influence of life history variation and habitat on mercury bioaccumulation in a high-order predatory fish in tropical Australia

Mercury distribution and bioaccumulation in aquatic ecosystems of tropical Australia is poorly characterised. Barramundi (Lates calcarifer), a widespread high-order predator in both fresh and coastal marine waters of the region, fulfils requirements for a bio-indicator of mercury contamination. In a study of the Mary River system of the Northern Territory, total mercury in the muscle tissue of 300 specimens gathered over four years (2013–2017, across both wet and dry seasons) was determined by direct combustion–atomic absorption spectrometry. Source of nutrition and trophic position of barramundi in the food web was also estimated via carbon and nitrogen isotopes (δ13C and δ15N), respectively, in tissue by stable isotope mass spectrometry, and determination of strontium isotopes (87Sr/86Sr) in otoliths by laser ablation–ICPMS differentiated between freshwater and saltwater residence. Results showed that fish moving into freshwater floodplain wetlands concentrated mercury in muscle tissue at approximately twice the level of those that remained in saline habitats. Resolving life histories through otolith analyses demonstrated diversity in mercury bioaccumulation for individual fish of the same migratory contingent on the floodplains. Although trophic level (δ15N), capture location, source of nutrition (δ13C), and age or size partly predicted mercury concentrations in barramundi, our results suggest that individual variability in diets, migration patterns and potentially metabolism are also influential. Using a migratory fish as a bio-indicator, and tracking its life history and use of resources, proved valuable as a tool to discern hot spots in a coastal waterway for a contaminant, such as mercury.

Olive Oil Traceability Studies Using Inorganic and Isotopic Signatures: A Review.

The olive oil industry is subject to significant fraudulent practices that can lead to serious economic implications and even affect consumer health. Therefore, many analytical strategies have been developed for olive oil’s geographic authentication, including multi-elemental and isotopic analyses. In the first part of this review, the range of multi-elemental concentrations recorded in olive oil from the main olive oil-producing countries is discussed. The compiled data from the literature indicates that the concentrations of elements are in comparable ranges overall. They can be classified into three categories, with (1) Rb and Pb well below 1 µg kg−1; (2) elements such as As, B, Mn, Ni, and Sr ranging on average between 10 and 100 µg kg−1; and (3) elements including Cr, Fe, and Ca ranging between 100 to 10,000 µg kg−1. Various sample preparations, detection techniques, and statistical data treatments were reviewed and discussed. Results obtained through the selected analytical approaches have demonstrated a strong correlation between the multi-elemental composition of the oil and that of the soil in which the plant grew. The review next focused on the limits of olive oil authentication using the multi-elemental composition method. Finally, different methods based on isotopic signatures were compiled and critically assessed. Stable isotopes of light elements have provided acceptable segregation of oils from different origins for years already. More recently, the determination of stable isotopes of strontium has proven to be a reliable tool in determining the geographical origin of food products. The ratio 87Sr/86Sr is stable over time and directly related to soil geology; it merits further study and is likely to become part of the standard tool kit for olive oil origin determination, along with a combination of different isotopic approaches and multi-elemental composition.

Estimation of radionuclides global fallout levels in the soils of CIS and eastern Europe territory

This study is devoted to the estimation of radionuclides global fallout levels in the soils of Commonwealth of Independent States (CIS) and Eastern Europe territory as a result of nuclear explosions. 58 standard soil samples were used, which were selected in different soil and climatic areas of the territory of CIS and Eastern Europe in 1978–2018. All samples were measured by gamma spectrometry. Determination of plutonium isotopes and strontium was performed according to the method of the joint determination of these radionuclides from one sample. IN the samples considered in this work, the content of 60Co, 154Eu, 155Eu was below the detection limits, which were 0.4; 1.0 and 1.0, respectively. Natural radionuclides analysis results indicated that the obtained samples are typical soil samples without its abnormal contents. The content of 137Cs, 90Sr, 239+240Pu in a 20 cm soil layer due to global fallout is (3.9 ± 1.7), (2.2 ± 0.8), (0.18 ± 0.08) Bq/kg respectively, which considering the distribution of these radionuclides by depth and average soil density is (1.2 ± 0.5) kBq/m2 for 137Cs, (0.42 ± 0.15) kBq/m2– 90Sr and (55.0 ± 24.0) Bq/m2– 239+240Pu. The isotopic ratios137Cs/90Sr and 137Cs/239+240Pu for the territory of CIS and Eastern Europe are at the level (2.0 ± 0.71) and (25 ± 15), respectively.

New method for simultaneous determination of dissolved organic carbon and its stable carbon isotope ratio in liquid samples: environmental applications

ABSTRACT This study reports the development of an all-in-one elemental analyser isotope ratio mass spectrometry (EA-IRMS) system modified for simultaneous analysis of dissolved organic carbon (DOC) concentration and its stable carbon isotope footprint (δ 13CDOC) in aqueous samples. The method involves a quantitative oxidation of DOC in a 200 µL liquid sample to CO2, after sample acidification and stripping by nitrogen. The detection limit of the method for DOC quantification was 0.2 mg C/L with an analytical precision of 12 %. Uncertainty of stable isotope determinations was 2 % at 0.2 mg DOC/L, while decreasing to 0.3 % at 20 mg DOC/L. Quantitative oxidation of DOC in aqueous samples was validated by using ring test water samples and Deep Sea reference seawater. The method performances of isotope analysis were evaluated by analysing different isotopic standard solutions. The applicability of the method was tested through the analysis of different environmental types of water, showing that δ 13CDOC ranged from – 23.30 to –31.85 ‰, allowing to characterize samples of different environmental origin. The developed method offers several advantages including rapidity, use of small sample volumes and minimal sample pre-treatment, making it a valuable tool for routine DOC concentration measurements paired with isotopic characterization.

The Main Elements of the Field Ice-wedge Sampling Strategies for Isotope and Radiocarbon Analysis

The main purpose of the paper is to create an optimal strategy for field testing of wedge ice for isotope and radiocarbon analyses. The scientific significance of this task is the need for a detailed isotopic characterization of well-dated sections with ice wedges. The solution of this problem will allow us to obtain a complete isotopic and paleotemperature scenario for the Holocene and the late Pleistocene in the north of Western Siberia, northern and central Yakutia, Chukotka, and the Arctic islands. Reliable ranges of isotopic composition values will be obtained as a result of the application of an improved method of wedge ice sampling. It will give a complete picture of isotopic variations in ice wedges during a certain period of its formation in combination with the age setting of the obtained isotope data. The main provisions of the optimal strategy for field testing of wedge ice for isotope and radiocarbon analyses are formulated. The innovativeness of the proposed technique consists in comparing of oxygen isotope and deuterium curves obtained from two parallel and quasi-synchronous ice wedges exposed by a single outcrop in the yedoma and Holocene deposits. Previously, it was believed that the sampling from different ice wedges in the single outcrop would give the same results. The preliminary studies carried out by the author show that this is not always the case. At the same depths, both identical and noticeably different isotopic determinations were obtained from samples from neighboring ice wedges. Predominantly horizontal sampling from ice wedges in yedoma deposits should still be referred to as an insufficiently developed procedure, it should be supplemented by vertical sampling from ice wedges. It is possible to develop criteria for excluding older 14С dates due to admixture of allochthonous organic material as inversions with vertical sampling only. This is impossible using horizontal sampling.

Role of rock glaciers and other high-altitude depositional units in the hydrology of the mountain watersheds of the Northern Patagonian Andes

Mountain depositional landforms are important units for freshwater supply in regions with water deficits and significant droughts during the summer season. In the Northern Patagonian Andes, the cold climatic events during the Pleistocene period left a large number of glacial and periglacial depositional landforms, among which a glacial cirque called La Hoya stands out. An analysis of geomorphological landforms, climatic data, soil temperature, flows in springs and streams, electrical conductivity measurements, and stable isotope determination of water, were made to study the hydrological role of these depositional mountain landforms. In this region, precipitations are concentrate during the winter season when an important snow cover accumulates and persists until spring. During winter and spring seasons, part of the snowmelt infiltrates, being kept in solid states inside the depositional landforms, and part of it contributes to the runoff between winter and summer. At the ends of spring and early summer, the snowmelt is the main water contribution to the La Hoya watershed. During late summer and autumn, the most important water contribution is from groundwater discharge. Where glacial ice is absent and the presence of permafrost is limited or non-existent, morphosedimentary units are important landforms for water storage and streams sustenance. This is the case of the city of Esquel, which depends exclusively on the “Los Bandidos” stream for water supply, which is sustained throughout the year by these landforms. The increase in temperature and the decrease in precipitation in this region highlights the importance of the high-altitude depositional landforms for the capture, storage, and distribution of water resources in the Northern Patagonian Andes.