Isotope Content Research Articles

Stable Isotope Analysis Reveals Common Teal (Anas crecca) Molting Sites in Western Siberia: Implications for Avian Influenza Virus Spread.

The wetlands of southwestern Siberia (SWS) are a crossroads of bird migration routes, bringing avian influenza (AIV) strains that were previously isolated in different regions of the continent to Siberia. It is known that Anseriformes that breed in SWS migrate for the winter to central Hindustan or further west, while their migration routes to southeast Asia (SEA) remain unconfirmed. Here, we mapped the molting sites of the migrating Common Teals (Anas crecca) via analyzing stable hydrogen isotope content in feathers of hunters' prey and supplemented the analysis with the genetic structure of viruses isolated from teals in the same region. Post-breeding molt of autumn teals most likely occurred within the study region, whereas probable pre-breeding molting grounds of spring teals were in the south of Hindustan. This link was supported by viral phylogenetic analysis, which showed a close relationship between SWS isolates and viruses from south and southeast Asia. Most viral segments have the highest genetic similarity and the closest phylogenetic relationships with viruses from teal wintering areas in southeast Asian countries, including India and Korea. We assume that the winter molt of SWS breeding teals on the Hindustan coast suggests contacts with the local avifauna, including species migrating along the coast to SEA. Perhaps this is one of the vectors of AIV transmission within Eurasia.

Chronological Study of Coal‐seam Water and its Implication on Gas Production in the South Qinshui Basin

AbstractThe knowledge of the residence time of formation water is fundamental to understanding the subsurface flow and hydrological setting. To better identify the origin and evolution of coal seam water and its impact on gas storage and production, this study collected coalbed methane co‐produced water in the southeast Qinshui Basin and detected chemical and isotopic compositions, especially 36Cl and 129I concentrations. The calculated tracer ages of 129I (5.2–50.6 Ma) and 36Cl (0.13–0.76 Ma) are significantly younger than the age of coal‐bearing formation (Pennsylvanian ‐ Cisuralian), indicating freshwater recharge after coal deposition. The model that utilises 129I/I and 36Cl/Cl ratios to constrain the timing of recharge and the proportion of recharge water reveals that over 60% of pre‐anthropogenic meteoric water entered coal seams since 10 Ma and mixed with residue initial deposition water, corresponding to the basin inversion in Cenozoic. The spatial distribution of major ion concentrations reveals the primary recharge pathway for meteoric water from coal outcrops at the eastern margin to the basin center. This study demonstrates the occurrence of higher gas production rates from wells that accept water recharge in recent times and suggests the possible potential of the non‐stagnant zones for high gas production.

An Assessment of Six Years of Precipitation Stable Isotope and Tritium Activity Concentration Records at Station Sv. Urban, Eastern Slovenia

We present data from six years (January 2016–December 2021) of monitoring the isotope composition of precipitation at the Sv. Urban station in Eastern Slovenia. The 68 precipitation samples were collected as a monthly composite. The complete dataset (193 data pints) includes information on the stable isotope composition of hydrogen (δ2H) and oxygen (δ18O) and tritium activity concentration (A), obtained using isotope ratio mass spectrometry (IRMS) and liquid scintillation counting (LSC) following electrolytic enrichment (EE), respectively. The isotope data, together with meteorological data, are reported. Calculations of the deuterium excess (d-excess), monthly, seasonal, and annual unweighted and precipitation-weighted means and local meteoric water lines (LMWLs) were conducted. The mean values for δ2H, δ18O, d-excess, and A, weighted by precipitation, were −59.9‰, −8.81‰, 10.6‰, and 7.7 TU. The disparities between unweighted and precipitation-weighted δ2H, δ18O, d-excess, A, and LMWLs underscore the significance of non-uniformly distributed precipitation. Annual variations in slope and intercept of the LMWLs emphasize the importance of longer data records (48+ months) to capture consistent trends, while combining data over longer periods may distort accuracy due to distinct isotope differences between individual years related to the variability of climate conditions typical for Slovenia.

Geochemical and Isotopic Constraints on the Recharge and Salinization Origin of Groundwater Aquifers in El Rina–Nihayaat, South Sinai, Egypt

The Sinai Peninsula is located in the arid regions of Egypt where groundwater is the sole source for drinking and irrigation and future development. Regular assessment of the geochemical processes governing the groundwater quality is important in arid regions and paleo-aquifers. This research focuses on investigating the groundwater sustainability of the Upper Cretaceous Aquifer (UCA) located at El Rina–Nihayaat area, Southwestern Sinai Peninsula. The study aims to evaluate the main source of groundwater recharge and investigate factors deteriorating groundwater quality. The study is based on the geochemical and isotopic analyses of 31 groundwater samples tapping the UCA. The groundwater flows toward the Gulf of Suez. The groundwater salinity ranges from 1078 mg/L to 13090 mg/L indicating brackish to saline water. Two main water types have been delineated: Cl-Na and Cl-Ca indicating the final stage of groundwater evolution and leaching and dissolution of aquifer matrix of marine origin. The spatial distribution of the groundwater salinity and major ions (Na+, K+, Ca2+, Mg2+, SO42-, and Cl-) increase toward the Gulf which coincides with the direction of the groundwater flow, while bicarbonate increases toward the upstream watershed. Most of the groundwater samples tapping the UCA are depleted with the isotopic content of the stable isotopes where they range from -4.43 ‰ to -6.37 ‰ for δ18O and -28.3 ‰ to -40.2 ‰ for δ2H. The groundwater samples are depleted relative to the recent rainwater and enriched to the Nubian Sandstone located underneath the UCA indicating mixing from both source(s). The mixing estimated percentages from the recent rainwater using calibrated geochemical NETPATH model range between 48.6% to 88.5% while the upward Leakes from the Nubian water ranges between the recent rain and the paleo-Nubian water ranges between 48.6 % and 88.5 % from the meteoric rainwater, while the upwelling recharge from the paleo-Nubian groundwater ranges between 11.5 % to 51.4 %. The factorial analyses indicate three main factors governing the geochemistry of groundwater in the UCA: including water-rock interactions, meteoric recharge from annual precipitation, and upward leakages from the underneath paleowater. 
 Further exploration for the UCA is recommended to determine the promising zones receiving a considerable amount of the recent rainfall.

Boron-Containing MOF Nanoparticles with Stable Metabolism in U87-MG Cells Combining Microdosimetry To Evaluate Relative Biological Effectiveness of Boron Neutron Capture Therapy.

Accurate prediction of the relative biological effectiveness (RBE) of boron neutron capture therapy (BNCT) is challenging. The therapy is different from other radiotherapy; the dynamic distribution of boron-containing compounds in tumor cells affects the therapeutic outcome considerably and hampers accurate measurement of the neutron-absorbed dose. Herein, we used boron-containing metal-organic framework nanoparticles (BMOFs) with high boron content to target U87-MG cells and maintain the concentration of the 10B isotope in cells. The content of boron in the cells could maintain 90% (60 ppm) within 20 min compared with that at the beginning; therefore, the accurate RBE of BNCT can be acquired. The effects of BNCT upon cells after neutron irradiation were observed, and the neutron-absorbed dose was obtained by Monte Carlo simulations. The RBE of BMOFs was 6.78, which was 4.1-fold higher than that of a small-molecule boron-containing agent (boric acid). The energy spectrum of various particles was analyzed by Monte Carlo simulations, and the RBE was verified theoretically. Our results suggested that the use of nanoparticle-based boron carriers in BNCT may have many advantages and that maintaining a stable boron distribution within cells may significantly improve the efficiency of BNCT.

Intraspecific plasticity and co-variation of leaf traits facilitate Ficus tinctoria to acclimate hemiepiphytic and terrestrial habitats.

Despite intensive studies on plant functional traits, the intraspecific variation and their co-variation at the multi-scale remains poorly studied, which holds the potential to unveil plant responses to changing environmental conditions. In this study, intraspecific variations of 16 leaf functional traits of a common fig species, Ficus tinctoria G. Frost., were investigated in relation to different scales: habitat types (hemiepiphytic and terrestrial), growth stages (small, medium and large) and tree crown positions (upper, middle and lower) in Xishuangbanna, Southwest China. Remarkable intraspecific variation was observed in leaf functional traits, which was mainly influenced by tree crown position, growth stage and their interaction. Stable nitrogen isotope (δ15N) and leaf area (LA) showed large variations, while stable carbon isotope (δ13C), stomata width and leaf water content showed relatively small variations, suggesting that light- and nitrogen-use strategies of F. tinctoria were plastic, while the water-use strategies have relatively low plasticity. The crown layers are formed with the growth of figs, and leaves in the lower crown increase their chlorophyll concentration and LA to improve the light energy conversion efficiency and the ability to capture weak light. Meanwhile, leaves in the upper crown increase the water-use efficiency to maintain their carbon assimilation. Moreover, hemiepiphytic medium (transitional stage) and large (free-standing stage) figs exhibited more significant trait differentiation (chlorophyll concentration, δ13C, stomata density, etc.) within the crown positions, and stronger trait co-variation compared with their terrestrial counterparts. This pattern demonstrates their acclimation to the changing microhabitats formed by their hemiepiphytic life history. Our study emphasizes the importance of multi-scaled intraspecific variation and co-variation in trait-based strategies of hemiepiphyte and terrestrial F. tinctoria, which facilitate them to cope with different environmental conditions.

ВЗАЄМОДІЯ Н(D,Т)О З МІНЕРАЛЬНИМИ АДСОРБЕНТАМИ У СТАЦІОНАРНИХ СИСТЕМАХ

Background. The theoretical basis of the experiments is the idea that the significant adsorption properties of layered silicates of the montmorillonite and palygorskite groups and clinoptilolite with a developed specific surface due to the dynamic nature of adsorption-desorption processes due to kinetic isotope effects can ensure priority retention of mineral particles of more inert hydroxide groups ОТ– near the adsorption surfaces. Methods. Cherkasy bentonite with a montmorillonite content of 75 % (hereafter montmorillonite), Varvarivska saponite, and Sokyrnytsky clinoptilolite were used for the experiments. Experiments were performed in stationary mode in hermetically sealed containers (two-phase watermineral system). Results. During the first 7 days of interaction of the aqueous and mineral phases, the specific activity of tritium in the working solution decreased by 31.8–69.5 %. Subsequently, during the 92 days of interaction of the aqueous solution of H(D,T)O with mineral adsorbents, the change in the specific activity of tritium did not exceed 2–4 %. At the same time, the initial concentration of deuterium in the working solution of Н(D,Т)О of two-phase water-mineral systems decreased by only 0.8–14 %, ranging from 0.0066 % to 0.0408 %. During the experiment, in closed water-mineral systems, a partial interphase redistribution of the initial stock of hydrogen isotopes, which was accumulated in the initial working solution Н(D,Т)О, took place. In the process of adsorption of the solution by mineral adsorbents, the initial moisture in the mineral phase was replaced by Н(D,Т)О and the content of hydrogen isotopes increased in them. The content of tritium in the adsorbate, depending on the mineral type of the adsorbent, increased by 31.8 to 69.5 %. Concentration of deuterium increased by 10.1–48.6 %, which was due to the different adsorption capacity of mineral adsorbents. Adsorption of the H(D,T)O working solution by mineral adsorbents was accompanied by fractionation of heavy hydrogen isotopes. Сonclusions. Аs a result of the interaction of the Н(D,Т)О solution with mineral adsorbents, kinetic isotope effects determined the priority retention of more inert hydroxide ОТ-groups than OD- groups near the adsorption surface of mineral particles. Consequently, interphase fractionation of heavy hydrogen isotopes occurred in stationary water-mineral systems. The coefficients of tritium interphase fractionation range from α = 1.26 for palyhorskite to α = 2.96 for clinoptilolite. For deuterium, this indicator is equal to α = 0.89 for clinoptilolite and to α = 1.10 for saponite.

Kinetics of hydrogen absorption/desorption in the Zr-2.5Nb alloy.

The Zr-2.5Nb alloy is a typical pressure tube material in heavy water nuclear reactors, and an increase of hydrogen isotope content in the alloy during service can pose major safety risks; hot vacuum extraction-mass spectrometry is an efficient method for evaluating hydrogen isotope concentrations in the Zr-2.5Nb alloy. This work investigates the kinetics and thermodynamic properties of deuterium (D) absorption and desorption of the Zr-2.5Nb alloy using the constant volume adsorption method and the hot vacuum extraction method. In addition to the previously reported volume contraction model, it was observed that at 600 °C and above, the reaction between D2 and Zr-2.5Nb is dominated by diffusion, while the reaction is predominantly influenced by surface adsorption and dissociation below 600 °C. Phase transition sequence of Zr-2.5Nb deuterides during non-isothermal desorption was established using quantitatively calibrated thermal desorption spectra combined with the phase transition process of deuteride decomposition. These results can provide important references for optimizing the process parameters of the hot vacuum extraction-mass spectrometry method.

Studying the possibility of applying spectral methods for the analysis of chemical elements and radionuclides

This article presents the results of a study of the possibility of using spectral methods for analyzing chemical elements and radionuclides. As is known, in uranium production processes, chemical elements and radionuclides behave differently and they are distributed in different concentrations. Therefore, the main tasks of analytics are to determine the concentration and specific activity values of chemical elements and radionuclides in samples taken from various uranium products of uranium production. The magnitude of radiation factors at a local location of a uranium product is assessed by determining the values of these factors and the amount of various radionuclides contained in these samples. In laboratory conditions, the concentrations of U were determined by X-ray fluorescence analysis, the specific activity of 230Th, 226Ra, 40K and 137Cs was determined by gamma spectrometric analysis, and the isotope concentrations of 234U, 235U, 238U were determined by alpha spectrometric analysis. The results obtained were compared with the passport data of standard samples - SOUR, OSK-6, OSK-9, OSGI. Determining the concentration and specific activity values of various chemical elements and radionuclides in uranium products is of scientific and practical interest, and solving this issue is an urgent task of nuclear physics and analytics.

Isotopic study of rainfall and definition of local meteoric water lines: Case of the rainfall stations of the city of Bangui in Central African Republic

The study of the isotopic composition of rainwater discussed in this article allows isotopic characterization of rainfall recorded in the Bangui region over 11 years at two stations. It will highlight the relationships between isotopes, climatic parameters, and temporal variation before defining the local meteoric line, which constitutes the reference point for the region. The results obtained after a follow-up of eleven years without interruption showed two major physical effects, the effect of the rainfall influences more strongly the composition in isotopes, the contents in isotopes vary inversely with the precipitation. For example, heavy rainfall in August and September saw a strong depletion of δ¹⁸O and δ²H contents. These values reach up to -4.96‰ for δ¹⁸O and -28.3‰ for δ²H. Similar, although weaker, effects are observed for July and October precipitation. We also note that the isotope contents at the Bangui University station are lower than those measured at the Bangui Sodeca station located at 386 m altitude on the Lower Ubangi Hill, which is similar to a pseudo-altitude effect. The evolution of stable isotope content in water as a function of meteorological parameters (temperature, rainfall, altitude) has allowed us to determine a local meteorological line for the city of Bangui from two measuring stations defined as follows: δ2H = 7.6 × δ18O + 10.4 (R2 = 0.9909) Université de Bangui, δ2H = 8.4 × δ18O + 12.5 (R2 = 0.9909) Bangui-Sodeca and δ2H = 7.9 × δ18O + 11.3 (R2 = 0.9939) Bangui local meteoric water lines.

Trophic characteristics of pelagic and bottom nekton in certain water masses in the western Chukchi Sea, by δ15N and δ13C data

To compare the trophic characteristics of pelagic- and bottom-dwelling fish in the western Chukchi Sea, isotopic composition of carbon and nitrogen (δ13С and δ15N) is considered separately for the Subarctic water mass (invaded from the Bering Sea) and local Arctic water mass. In summer of 2018 and 2019, the proper water mass occupied mostly the area southward from 71оN and the latter one – northward from this latitude. The isotopic composition of both pelagic and bottom nekton in the southern area was characterized by higher values of δ13C (up to 2 % higher) and low values of δ15N (up to 1 % lower) in comparison with those in the northern area. That was interpreted that in the southern area, within the water from the Bering Sea, more than 90 % of the sampled bottom fish species were linked with prey from the bottom community. In the northern area, within the Arctic water, all samples of bottom fish were characterized by minimal content of heavy carbon δ13C isotope, comparable with the values in samples of pelagic fish that indicated a significant role of pelagic prey in nutrition of the bottom nekton.

A Monte Carlo Fuel Assembly Model Validation Adopting Post Irradiation Experiment Dataset

Abstract Within an energy system where nuclear reactors will likely play a critical role, it is fundamental to have access to accurate and reliable computational tools that can predict the plants' behavior under different operating conditions; compared to other energy sources, models and analysis methods for nuclear systems should be able to provide, among other things, detailed information on reactor criticality and fuel evolution. Thanks to the advancements in computational hardware, using three-dimensional codes to obtain a local description of the reactor core has now become feasible, not only for what concerns deterministic codes but also for Monte Carlo (MC) based codes. Those computational methods must be compared with experimental measurements to assess their reliability. For this reason, the 3D Monte Carlo code serpent is currently being validated for light water reactor fuel cycle simulations. This work will compare the isotopic concentrations measured in a Post-Irradiation Experiment (PIE) and the results of the Monte Carlo routine, examining the Takahama-3 fuel assembly test case. Since key information related to the history of the plant under consideration is available, it was possible to follow the depletion cycles of two fuel rods (SF95 and SF97) placed in two separate assemblies. From literature reports, more than 35 nuclide species have been measured at different axial locations by destructive analysis following several radiochemical techniques. A sensitivity analysis, aiming to evaluate the impact of design features on the results, was carried out investigat-ing the cross section libraries, the simulation time Discretization and the imposition of an axial time-varying temperature. During the process, systematic sources of geometry-related errors were analyzed as well. Over-all, the model showed good agreement with the experimental data under an acceptable error threshold. The sensitivity studies also showed how the prediction capability could be increased up to +6%, adopting a realistic temperature mesh for the fuel instead of a uniform temperature approach. Finally, this analysis will focus more deeply on the Antimony-125 evolution, whose concentration is the one with the worst agreement to the experimental dataset not only for this work but also for other benchmarks available in the literature: results will show how the prediction error for this nuclide is systematic for all considered codes, and look for possible causes.

Stable isotope composition and concentration systematics of Ca and trace elements (Zn, Sr) in single aliquots of fossil bone and enamel

Measurements of modern bone and tooth enamel show that calcium stable isotopes (δ44Ca), zinc (δ66Zn), and strontium (δ88Sr) have great potential as ecological and dietary tracers for studies on fossil material. Despite the fact that these three elements can be recovered using sequential chromatographic extraction from a single aliquot, a multi-proxy study has not been attempted yet, which would allow a less destructive analysis of precious fossil material. The present study consists of analyzing δ44Ca, δ66Zn, δ88Sr, and 87Sr/86Sr values in fossil bone and tooth enamel of carnivore and herbivore mammals from the Camiac cave (Upper Pleistocene, Gironde, France). Our study aims at (1) developing a protocol for Ca, Zn, and Sr stable isotope analyses from a single fossil bone or enamel aliquot; (2) testing the respective preservation of biological isotopic signatures in bone and tooth enamel; and (3) comparing the patterning of the different isotopic systems in a fossil mammal community. In the present study, fossil enamel samples have not been leached, as it has been done so far for Zn isotope analyses, but fossil bone samples have been leached using diluted acetic acid or were left unleached. Using inclusive statistical analyses, we identify the effect of leaching on bone chemical compositions, and the concentration and isotope composition of Ca, Zn, and Sr in leached bone and unleached enamel show no sizeable diagenetic overprint. We report for the first time δ66Zn values in fossil bone. The results show that bone δ66Zn values mirror the pattern already observed in enamel, e.g., a significant trophic 66Zn depletion between herbivores and carnivores. Bone δ44Ca and δ88Sr values also mirror those in enamel, and the results highlight a clear distinction between ruminants and non-ruminants, the latter being 44Ca-enriched. The present study focuses on the importance of analyzing several isotopic systems in a single fossil bone or enamel aliquot and shows encouraging results for the preservation of biological isotopic signatures in fossil bone, despite the longstanding dread of a so-called associated pervasive diagenesis. The present study will therefore be useful to consider any precious fossil material with limited destructive sampling possibilities.

Analytical Studies on the Radionuclide Levels of Sediment and Water in an Agricultural Environment in the Egyptian Delta

This paper is an environmental investigation of the concentration values of radioisotopes and hazardous elements, aimed to shed light on industrial pollution and the effect of using fertilizers in the period of irrigation water drainage from cultivated lands, especially in the River Nile, irrigated, and draining channels in the middle portion of the Egyptian river delta. Different samples were analyzed, both for water and sediment. Many physical and chemical characteristics of samples were investigated. Among them are the quantitative measure of the acidity or basicity of aqueous or other liquid solutions (pH), grain size, and the total organic matter content (TOM) have been determined for sediments. pH and TDS, beside other types of pollutants, were determined for water samples. The water and sediment samples pH are slightly alkaline. The mean value of TDS for water samples is 488 mg/l, while he usual TDS value in river is 500 mg/l. The TOM values show that the sediment samples are poor in organic matter content. The bicarbonate range in the water samples is smaller than the same range in river water. The levels of Ra-226, Th-232, and K-40 activity in sediments are highly correlated. Natural radionuclides seem to correlate with the artificial Cs-137 in sediment. For this peruse, a 240 cm3 high-purity germanium reagent Type-B was used to quantify the levels in each sample with a relative accuracy of 50 %. The radioactive element K-40 is having a typical value of 12.5 Bq/kg. The concentrations of both Cu beside Zn in water samples is smaller if compared with values that quoted by the WHO, the US-EPA, and the EC. It was also found that the average levels for both Cd and Mn are found to be close to the internationally recommended levels. The water and sediments in the southern part of the canal contain higher concentrations of heavy metals and radioactive isotopes than in the rest of the canal.

HR GRS-HPGe as NDT method for quantification of uranium and 235U content in process stream samples from UO2 fuel production facilities

Abstract Uranium concentration and uranium isotopic content are two important and critical parameters for any nuclear fuel fabrication facilities. In the present study emphasis has been given on the usage of high resolution gamma ray spectrometric (HR-GRS) technique with HPGe detector for the determination of uranium and 235U content in uranium process stream samples. The work has been carried out with an aim to give quick analytical feedback to production facility and also to minimize the generation of analytical waste. These are important requirements for any industrial lab with high analytical load attached to production facility. In this paper a simple and a non-destructive testing (NDT) method has been described for quantification of uranium and 235U content in samples received from UO2 fuel production facilities using HR-GRS technique with high purity germanium (HPGe) detector. A 185.7 keV line of 235U has been used for quantification of uranium in process solutions containing 1 g/L to 600 g/L of uranium covering both aqueous and organic process stream solutions. The results have been compared with that of Davies and Gray method. The limitations associated with gamma ray emitted from daughter products of 238U and self-induced or self-excited X-ray fluorescence lines of uranium have also been studied. Multi Group Analysis of Uranium (MGAU) software code has been used for measurement of 235U content in variety of samples. The results obtained are compared with that of results by thermal ionization mass spectrometer (TIMS).

Isotopic and Remote Sensing-Based Characterisation of a Rainfall Event over Western Sierra de Gádor (Spain): Implications for Carbonate Aquifer Recharge

Stable water isotopes are widely recognised as essential tools to trace processes within the hydrological cycle and to disentangle complex phenomena, such as regional–local atmospheric patterns, infer water balances or characterise the aquifer recharge. In this work, we characterised two post-summer precipitation events over the western sector of Sierra de Gádor through the analysis of the rainwater δ18O and δ2H ratios, ionic composition and, complementarily, remote sensing products to define the atmospheric circulation during the rainfall episodes. This information enabled us to discern the moisture source, formation conditions and orographic influence on the rain episodes, and to better define the origin of the groundwater recharge and its dynamics in the study area. Although the samples share a common moisture source (W Mediterranean), they display substantial differences in their isotopic compositions. Such differences are attributable to sub-cloud evaporation processes that mask their Mediterranean origin, and to the strong influence of the orography on the hydrochemical and isotopic characteristics of the rainfall at the local level. The groundwater presents a very stable isotopic content and is strongly depleted in heavy isotopes, evidencing that most of the aquifer recharge takes place at very high altitudes and primarily during winter, when the influence of evaporation is attenuated.

Changes in geochemical and isotopic contents in groundwater before seismic events in Ischia Island (Italy)

We analysed the hydrogeochemical and isotopic contents in groundwater for the period 2002–2020, in the Ischia Island, a volcanic island in Southern Italy, and compared them with seismic events that occurred in the same period. The study is based on a large hydrochemical database, which includes chemical (major and minor compounds, metals and trace elements) and isotopic analyses (δ18O and δ2H). For each of the 34 seismic events occurred in the studied period, we considered coordinates, date, time, depth and magnitude. To exclude the influence of meteorological variability on the hydrochemistry, we examined rainfall time series measured in four stations located in the island. Results show hydrogeochemical anomalies for some chemical elements observed months before the seismic events. Arsenic, electrical conductivity, chromium and vanadium have been identified as potentially affected by hydrogeochemical anomalies related to the earthquakes. The variations in stable isotopes (δ2H and δ18O) in groundwater also seem associated with the earthquakes.This study aims to contribute to the individuation of components in groundwater prone to register sudden changes related to seismic events and it highlights the need of a continuous and long-term hydrogeochemical monitoring in seismic areas. Indeed, the conclusions of this study must be further confirmed by a future continuous monitoring of major compounds, trace elements and isotopes in groundwater to evaluate the effective temporal coincidence/lag with the seismic events.

Nuclear Spin-Depleted, Isotopically Enriched 70 Ge/28 Si70 Ge Quantum Wells.

The p-symmetry of the hole wavefunction is associated with a weaker hyperfine interaction, which makes hole spin qubits attractive candidates to implement quantum processors. However, recent studies demonstrate that hole qubits are still very sensitive to nuclear spin bath, thus highlighting the need for nuclear spin-free germanium (Ge) qubits to suppress this decoherence channel. Herein, this work demonstrates the epitaxial growth of 73 Ge- and 29 Si-depleted, isotopically enriched 70 Ge/silicon-germanium (SiGe) quantum wells. The growth is achieved by reduced pressure chemical vapor deposition using isotopically purified monogermane 70 GeH4 and monosilane 28 SiH4 with an isotopic purity higher than 99.9% and 99.99%, respectively. The quantum wells consist of a series of 70 Ge/SiGe heterostructures grown on Si wafers. The isotopic purity is investigated using atom probe tomography (APT) following an analytical procedure addressing the discrepancies caused by the overlap of isotope peaks in mass spectra. The nuclear spin background is found to be sensitive to the growth conditions with the lowest concentration of 73 Ge and 29 Si is below 0.01% in the Ge well and SiGe barriers. The measured average distance between nuclear spins reaches 3-4 nm in 70 Ge/28 Si70 Ge, which is an order of magnitude larger than in natural Ge/SiGe heterostructures.The spread of the hole wavefunction and the residual nuclear spin background in APT voluminals comparable to the size of realistic quantum dots are also discussed.

Active feeding of downstream migrating juvenile pink salmon (Oncorhynchus gorbuscha) revealed in a large Barents Sea river using diet and stable isotope analysis.

The recent, rapid spreading of non-native pink salmon Oncorhynchus gorbuscha in the North Atlantic area has raised concerns about their possible negative impacts on native salmonid species. Potential interactions include competition for food resources during the short freshwater phase of juvenile O. gorbuscha, but little is known about their feeding behavior in the newly occupied North Atlantic rivers. Using stable isotope and stomach content analyses, patterns of freshwater feeding of non-native O. gorbuscha fry were studied in a large Fennoscandian river, the Teno, that discharges to the Barents Sea. Changes in stable isotope values (δ13 C, δ15 N, δ34 S) and stomach contents from the period of emergence (April to mid-May) to estuarine entry (late May/June) were examined and provided both temporally integrated and short-term indicators of freshwater feeding dependency. In addition, the occurrence of juvenile O. gorbuscha and changes in their length and weight during their emergence/migration period were investigated. Juvenile O. gorbuscha were at the spawning grounds from April through to mid-May with abundance peaking in mid-May. Fish moved to the estuary by late May and their abundance decreased toward June, and their body size increased concurrently. Stomach analyses indicated no feeding activity in April-early May in the spawning areas, but the stomach fullness indices increased markedly in fish sampled in the estuary in May and June. The most important prey items in stomachs were Chironomidae and Ephemeroptera larvae. Significant changes in all analysed stable isotopes were detected among sample periods, with a peak in mid-May and June showing significantly lower values than other sample periods. A change from the higher values reflective of parental marine feeding to the lower values reflective of freshwater feeding indicated active in-river feeding by juveniles during the study period. The documented active freshwater feeding of non-native juvenile O. gorbuscha suggests potential resource competition with native fluvial fishes, particularly salmonids.

Январская палеотемпература воздуха в период МИС-3-2 в северо-восточной Якутии, реконструированная по высокоразрешающей записи изотопного состава сингенетических повторно-жильных льдов Батагайской едомы

The work is aimed at determining the age of ice wedges, as well as at characterizing winter temperature fluctuations during the formation of the Yedoma based on the isotopic composition of ice wedges in the unique outcrop of the Batagay mega-slump. The researchers carried out a detailed sampling from the Upper Ice Wedge Complex of the Batagay Yedoma, determined the isotopic composition in three ice wedges at different altitudes. The results of radiocarbon dating of organic matter from ice wedge confirm the time of syngenetic formation of the upper-tier ice wedges in the range from 27.2 to 30.8 thousand cal. years. Ice wedges of the lower tier, according to the results of radiocarbon dating of ice accumulated 44.7—47.9 thousand years ago simultaneously at different levels: 274—268 m and 224—227 respectively. The study of yedoma deposits and ice-wedge ice made it possible to obtain data on climatic fluctuations in a region with the most severe continental climate. Direct radiocarbon dating of syngenetic ice wedges provided dating of ice growth in the Batagay yedoma, data on the content of stable isotopes in the ice demonstrated stable and very harsh conditions of the winter season. The air paleotemperature in Batagay in January 47—42 and 30—25 thousand cal. years ago was consistently low about –51°C.