This study deals with the isotopic composition of monsoon precipitation in Southern Oman, specifically in the Salalah coastal plain and the adjacent Dhofar Mountains. Monsoon variability on the southern Arabian Peninsula has been described based on the oxygen isotope composition of various terrestrial archives, often on the millennial scale. However, the factors influencing the spatio-temporal variability of the oxygen isotope composition of today's monsoon precipitation have not yet been described for this region. Here, we present stable isotope ratios of oxygen and hydrogen for the Indian Summer Monsoon in the greater Salalah area. The precipitation amount-weighted mean isotope values along an elevation transect show lighter signatures at higher elevation, but generally low deuterium excess values ( d <10 ‰). To trace the origin and (short-term) history of the precipitation system, we applied a 3-step model incorporating evaporation of seawater, condensation, and sub-cloud evaporation. Our modelling exercise indicates that the classic elevation effect is quasi-negligible, and that sub-cloud evaporation is likely to be the main driver behind the encountered isotope pattern. This pseudo-elevation effect implies that the precipitation is not depleted in heavy isotopes with increasing elevation, but rather enriched with decreasing elevation. This effect may prevail in other (semi-arid) areas as well. • Monsoon precipitation was sampled at six sites along an elevation gradient in S-Oman. • Precipitation is isotopically lighter at higher elevations. • A 3-step model shows that the pattern is not caused by the classic elevation effect. • The system is governed by sub-cloud evaporation, causing a pseudo-elevation effect. • This effect may occur in other (semi-arid) areas too.

Study of isotopic effects of high-temperature corrosion of titanium beryllide Be12Ti in water vapor with different isotopic composition

Activation calculations were completed on the production of emerging beta-emitting radionuclides in the Budapest Research Reactor (BRR) for medical applications. MCNP6 was utilized to characterize the neutron field at the irradiation positions, while FISPACT-II software was used to predict the activities of the produced radionuclides. Target materials with natural isotopic compositions were irradiated in three different vertical channels of the BRR, and the specific activities of the radionuclides 161Tb, 111Ag, 199Au and 177Lu were determined using gamma-ray spectrometry. The validation has been successfully completed using ENDF/B-VIII.0 and TENDL-2017 nuclear data libraries. A few discrepant cases were identified which require further investigation.

Molecular hydrogen isotopic compositions of petroleum n-alkanes and its geological significance in the Mahu Sag, Junggar Basin, NW China

Temporal changes in carbon and oxygen isotopic composition of peatland Sphagnum mosses and implications for paleoenvironmental reconstructions

Despite its ubiquity in nature, some details of the animal olfactory system remain unclear. One such mystery is the mechanism by which olfactory receptors (ORs) recognize the olfactant molecules they bind to. Some evidence indicates that ORs can distinguish between molecules that differ only in isotopic composition, suggesting that olfactants' vibrational modes may play a role in their recognition. In 2023, the first experimental structure of a human olfactory receptor-OR51E2-was produced, providing opportunity to shed additional light on this problem computationally. We simulate the infrared spectrum of the olfactant propionate ([Formula: see text]), as well as all its possible deuterations, in the OR51E2 binding site by quantum mechanics/molecular mechanics, with atomic positions taken at 25 time points over a 500ns molecular dynamics simulation. The protein environment does not change the vibrational spectrum qualitatively, even at physiological temperature. The high-frequency C-H modes are about [Formula: see text] higher in energy than their deuterated counterparts, while the modes associated with the carboxyl group are almost unaffected by the C/H isotopic substitution. Because [Formula: see text] binds to OR51E2 primarily via the carboxyl end, this result means that a vibrational component to propionate detection is unlikely.

ABSTRACT Intense rainfall events play a critical role in groundwater recharge across tropical regions, including Indonesia. In this study, we employ stable isotope data (δ18O, δ2H) from precipitation and groundwater, along with the chloride mass balance (CMB) method, to investigate recharge dynamics. The results indicate a clear bias in groundwater recharge toward heavy rainfall. At 20 of the 27 sites across Indonesia, heavier rainfall events are consistently associated with more isotopically depleted signatures compared to less intense rainfall, reflecting the amount effect. Groundwater isotope data from 16 sites further support this pattern, consistently indicating recharge predominantly occurs during high-intensity precipitation. In East Kalimantan, groundwater isotopic compositions align more closely with daily intense rainfall events than with monthly averages, suggesting that recharge is primarily event-driven. We estimate that 12-28% (as an upper bound) of recharge in East Kalimantan originates from precipitation, with intense rainfall events (>75th percentile) contributing up to 57% of total recharge.

Abstract. Accurate determination of the methane isotopic composition (δ13CH4) is essential for attributing emission sources of methane (CH4). However, for measurements with optical instruments, spectral interference from water vapor and instrumental drift often introduce substantial biases in δ13CH4 measurements, particularly for humid air measurements. Although multiple calibration strategies exist, a systematic evaluation of their performance under diverse field conditions remains lacking. Here, we evaluate two calibration strategies for a cavity ring-down spectrometer: a delta-based calibration for δ13CH4 and an isotopologue-specific calibration for 12CH4 and 13CH4. We performed laboratory experiments over a water vapor range of 0.15 %–4.0 % to establish empirical correction functions, quadratic for 12CH4 and 13CH4, and linear for δ13CH4, to remove humidity-induced biases. These correction functions were then applied to field measurements in both dried air at the SORPES stie and humid air at the Jurong site. At the SORPES site where air samples were dried using a Nafion™ dryer, the mean difference in δ13CH4 between the two strategies was ∼0.29 ‰. In contrast, for humid air at the Jurong site, significant inter-method difference (Δδ13CH4) was observed, with which exhibiting a strong correlation with 1/CH4, indicating non-linear spectral effects are most pronounced at lower CH4 concentrations and compromise the performance of delta-based calibration. Notably, only the isotopologue-specific calibration, coupled with an explicit water vapor correction, delivered stable and accurate δ13CH4 measurements across all conditions. This work underscores the need for robust calibration strategies to minimize bias in CH4 isotopic composition measurements.

Abstract Symbiotic relationships of microorganisms including eukaryotic algae and prokaryotes affect holobiont nitrogen metabolism and provide survival advantages in extreme environments; however, the influences of different symbionts on nitrogen metabolism in host organisms remain unclear. By tracing the nitrogen isotopic composition (δ 15 N) of amino acids (AAs), it is possible to constrain the biosynthetic sources and trophic interactions. We targeted reef-dwelling large benthic foraminifers hosting species-specific symbiotic algae to identify the trophic positions of multiple species with distinct feeding strategies. We measured δ 15 N in AAs of bulk organic matter and of foraminiferal shells and compared the feeding strategy of each species with its estimated trophic position (TP). Estimated TPs based on δ 15 N in AAs were inconsistent with respect to species-specific feeding strategies. In particular, Amphisorus kudakajimensis , which depends on heterotrophic feeding, showed light δ 15 N Glu and δ 15 N Phe and TP of ~ 1. A shared nutrient source for both host and symbionts and an interactive supply of trophic compounds may explain the low trophic position. The mixotrophic or heterotrophic TPs of Calcarinidae hosting endosymbiotic diatom with limited feeding (TP = 1.5–2.3) may be affected by bacterial heterotrophic processes. Differences in symbiotic algae (zooxanthellae and diatoms) may have influenced host’s nutritional strategies through functional variations in nitrogen metabolism. Large variations in δ 15 N Glu and δ 15 N Phe within single species suggested that large benthic foraminifers exploit multiple sources of nitrogen. Additional culture studies using different nitrogen sources could provide insights into detailed nitrogen metabolism of organisms with endosymbionts and role of associated organisms.

Anthropogenic lead (Pb) is pervasive in alpine environments of the Tibetan Plateau (TP). Nevertheless, the source apportionment of deposited Pb within glacierized regions of the Southeastern Tibetan Plateau (SETP)─where glacier shrinkage is most severe across the entire TP─remain poorly quantified. To address this gap, this study integrates newly obtained Pb isotopic data from cryoconite samples with published data sets to elucidate the spatial distribution of Pb isotopic compositions and quantitatively reveal the origins of anthropogenic Pb deposited in the extensively SETP glaciers. The results show that Pb isotopic ratios range from 1.166 to 1.204 for 206Pb/207Pb and from 2.446 to 2.525 for 208Pb/207Pb, with large variability. Moreover, distinct spatial heterogeneity in the isotopic compositions is observed, with a decreasing trend along the longitudinal gradient. Source apportionment demonstrate that Indian coal combustion represents the primary source of Pb in SETP glaciers, accounting for 75.5%, with the strongest influence occurring at glaciers situated at valleys. At the plateau scale, Pb derived from Indian coal combustion exerts the greatest impact on this region, with its contribution decreasing from 75.5% to 21.3% along the south-north transect.

The Kocayayla Pb–Zn ± Cu vein-type mineralization is located in the Biga Peninsula, northwestern Türkiye. This study aims to constrain the geological, geochemical, and isotopic characteristics of the mineralization and to clarify its genetic classification. The deposit is hosted mainly by andesitic and basaltic andesitic rocks as well as schists and is structurally controlled by E–W-trending strike-slip faults. Mineralogical and petrographic identifications, XRD analyses, whole-rock geochemistry, and sulfur isotope data were integrated to evaluate ore-forming processes. Mineralization is temporally and spatially associated with propylitic and phyllic to argillic alteration and is concentrated within zones of intense silicification and chloritization, accompanied by quartz, sericite, kaolinite/nacrite, chlorite, and carbonate assemblages. The ore assemblage is dominated by galena, sphalerite, and subordinate chalcopyrite, with minor fahlore-group minerals. Rare earth element patterns of ore samples (whole rock) overlap with those of the wall rocks, whereas Pb–Zn enrichment reflects selective hydrothermal metal transport. Sulfur isotope compositions show limited internal variation and indicate sulfur derived predominantly from H2S-dominated magmatic–hydrothermal fluids. Regional comparison of δ34S datasets and reported Au contents across the Biga Peninsula indicates that Au-rich intermediate-sulfidation epithermal systems exhibit broader and more variable sulfur isotope ranges, whereas Au-poor intermediate-sulfidation epithermal systems show relatively restricted and near-zero δ34S values. These features collectively support the classification of the Kocayayla mineralization as an Au-poor intermediate-sulfidation epithermal Pb–Zn system.

The Nanping pegmatite-type Nb-Ta deposit is one of the large-scale Li-Cs-Ta (LCT)-type pegmatite deposits in Southeast China. Nevertheless, the mineralization mechanism of this ore deposit remains unclear, primarily due to the lack of systematic research on the characteristics of ore-forming fluids and mineralization processes. To address this issue, analyses of the fluid inclusion characteristics, hydrogen–oxygen isotope compositions and in situ U-Pb geochronology of Nb-Ta minerals were performed on the No. 31 vein of the Nanping pegmatite deposit. In situ U-Pb dating of the Nb-Ta minerals with varying textures from different zones yields main mineralization ages clustered between 390 and 370 Ma, along with isolated younger ages around 270 Ma in specific mineral zones, indicating multiple mineralization episodes. The fluid inclusion homogenization temperatures of different zones range from 130 to 382 °C, and salinities between 2 and 16 wt% NaCl eqv, consistent with a medium-to-low temperature and salinity fluid system. Hydrogen and oxygen isotope data show that the ore-forming fluids were predominantly derived from magmatic fluids, mixed with later meteoric waters. This study clarifies the multistage mineralization history and fluid evolution of the Nanping pegmatite-type Nb-Ta deposit, providing key constraints for metallogenic models of pegmatite-hosted rare-metal deposits.

The results of simulating the fluxes of deuterium (D)/tritium (T) fuel particles in plasma and the fuel cycle of the FNS-ST fusion neutron source based on a spherical tokamak are presented for the 10 -W-power neutral beam injection (NBI) heating scenario. Previously, scenarios for 6-MW-power NBI heating with the injection of D beams, T beams, and D + T beams have been studied. In contrast to the simulations performed previously, in this study, ions were used instead of electrons in the transport equations when performing consistent simulations of the particle and heat fluxes using the SOLPS and ASTRA codes. This allowed for performing better estimates of the fluxes of the D/T fuel components that should be provided with the systems for gas puffing and processing. The confinement times obtained (including global ones) are comparable with those obtained when simulating the 6 -MW-power scenario. The D and T fluxes in the core and divertor plasmas of a tokamak obtained during the simulations were used to estimate the fluxes and to calculate the content of the fusion fuel components in the tokamak fuel cycle systems using the FC-FNS code. Feedback was implemented between the pumping and injection systems in the form of changes in the density and isotopic composition of the core and divertor plasmas. Simulations of the NBI heating scenarios with the injection of D and T beams with powers of up to 10 MW, performed for a fusion neutron source with a fusion power of up to 3 MW, showed that the neutron yield can be increased to 0.1 × 1019 s−1. When increasing the additional NBI heating power from 6 to 10 MW, the additional injector is involved, which will require processing a larger amount of gas from the NBI system. At the same time, an increase in the particle flux due to the beam injection will result in a decrease in the flux associated with the pellet injection. For the scenario with the T beam injection, the amount of tritium contained in the facility was less. It can be up to 110 g, while in the scenario with the D beam injection, the amount of tritium increased to 330 g.

Abstract The Taupo Volcanic Zone (TVZ) is a young volcanic arc producing large volumes of silicic magmas with crustal signatures that are traditionally attributed to crustal contamination and fractionation of mafic melt. Only the crustal signature in volumetrically minor mafic TVZ magmas has been linked to the trench sediment recycling. Here, we use combined Sr-Pb-Nd-Hf isotope and trace element systematics of mafic to felsic TVZ rocks and trench sediments recently recovered by the International Ocean Discovery Program to argue for a strong impact of recycled sediments on TVZ magmas. Mafic to felsic volcanic series form single binary isotopic mixing trends between a mantle and a homogeneous crustal component. We show that the composition of mafic and intermediate volcanic rocks with high Mg# (&amp;gt;50) and Eu/Eu* &amp;gt; 0.9 cannot be controlled by crustal contamination and fractionation. Instead, the data point to source contamination through terrigenous trench sediments above the décollement, which may be recycled via subduction and tectonic forearc erosion by the Hikurangi plateau and seamount collision. We propose that the mantle and the above-décollement sediments control the Sr-Pb-Nd-Hf isotopic compositions of mafic to intermediate TVZ volcanic rocks and also influence the felsic TVZ series next to transcrustal assimilation. Our results imply a lesser extent of crustal assimilation and fractionation in the genesis of felsic TVZ magmas than previously thought. Overall, we argue that subcrustal recycling is a viable alternative for creating crustal signatures in the TVZ volcanic rocks and that magma ascent through the thin crust may be fast and shallow magma storage short lived.

The cumulative effect of hydrologic processes in cascade reservoirs controls sulfur transport: Base on stable sulfur and oxygen isotope compositions

Diversity, abundance and stable isotope composition of winged Diptera (Insecta) emerging from temperate forest soil

Fluid evolution in the Naxi Fe polymetallic deposit, Eastern Kunlun, China: Insights from in-situ trace element and sulfur isotope compositions of pyrite and pyrrhotite

ABSTRACT In Mediterranean vineyards, soils are often managed with tillage or herbicides to limit weed growth and competition for resources. However, with rising concerns about water scarcity and climate change, cover crops are being reconsidered as sustainable alternatives to conserve soil moisture and support adaptation through better soil structure and biodiversity. Although they are often reported to decrease yields, this is not always the case, and the magnitude and timing of their competition for resources with vines are still not well understood. To address this gap, we examined vine and cover crop water uptake depth during veraison in August in a vineyard from Rioja Alavesa, Spain. We compared tillage (control treatment) with spontaneous cover crop. Using the isotopic composition of plant and soil water (δ 18 O and δ 2 H) and Bayesian mixing models, we found that the cover crop relied on water from the upper soil (100% from 0 to 30 cm), while vines under cover crop accessed water from shallow (~48% from 0 to 30 cm) and deeper soil layers (~52% from 30 to 100 cm). Despite cover crops and vines competing for water in the upper soil, the vine's ability to access water from both shallow and deeper soil horizons helped maintain its water status during veraison. Vines under tillage relied predominantly on water in the deeper soil (~73% from 30 to 100 cm). These results indicate that soil management strongly influences vine water uptake patterns. In our vineyard, the spontaneous summer cover crop did not compromise vine water availability during veraison.

Genetic study of the Shuangwang gold deposit in the Western Qinling, China: Constraints from monazite dating, S isotope, and Ca isotope compositions

Zooplankton trophic dynamics in response to upwelling phases in the eastern arabian sea: Insights from stable isotopes.