Search Results (1,684)

This study employs machine learning methods to estimate possible source regions from Andean lead isotopes, a novel approach for tracing the provenance of metal artifacts in this region. Two Random Forest coordinate models were trained to approximate geographic provenance. The latitude model uses ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb isotope predictors, plus three derived ratios. The longitude model uses the same predictors together with the latitude predicted by the first model, allowing the regression to incorporate broad spatial coherence in the Andean ore-lead system. The Random Forest models reached, on validation, 3.50° and 1.94° MAE for latitude and longitude, respectively. These moderate values support the use of the framework as a screening tool that generates a ranked shortlist of nearest isotopic matches, rather than as a source of single definitive coordinates. Additionally, K-means clustering and Euclidean distance analysis were used to link artifact isotope compositions to known sources. The models’ limitations and scope were documented to ensure appropriate use and interpretation. Full article

To clarify the pollution characteristics and source composition of heavy metals in the paddy soils of the Yellow River irrigation district of Ningxia, a total of 515 surface soil samples were collected, and the concentrations of As, Hg, Pb, Cd, and Cr were measured. Regional-scale pollution assessment and source apportionment were conducted using the geo-accumulation index, spatial interpolation analysis, and the Positive matrix factorization (PMF) model. Based on the regional pollution assessment and spatial distribution patterns, a representative area with relatively elevated Cd accumulation and more pronounced anthropogenic influence was selected for local-scale isotope investigation. Eight paddy soil samples and potential end-member samples were collected, and, combined with literature-based end-member data, Pb and Cd isotopes were analyzed using the MixSIAR Bayesian (version 3.1.12) mixing model to further constrain the sources of Pb and Cd in village soils. The results showed that some sampling points in the study area exceeded the soil background values, but none of the points surpassed the screening values for agricultural soil pollution risk, indicating that the overall risk of paddy soils in the study area remained low. Geo-accumulation index results indicated that As, Pb, and Cr were predominantly classified as unpolluted, whereas Hg and Cd showed more pronounced accumulation, with most sampling points reaching unpolluted to moderately polluted or higher. PMF results revealed that heavy metals in the study area primarily originated from natural sources, agricultural activities, coal combustion-related sources, and industrial–traffic mixed sources. Cd was mainly influenced by agricultural sources, Hg was primarily affected by coal combustion and related industrial activities, and Pb exhibited a mixture of multiple sources. Local isotope analysis in the representative area further indicated that industrial and agricultural sources were the main contributors to soil Cd, accounting for 34.3% and 33.1%, respectively. Pb was primarily derived from agricultural activities (38.1%), while coal emissions, industrial sources, natural sources, and traffic contributed 19.2%, 18.3%, 16.9%, and 7.5%, respectively, indicating a complex mixture of agricultural, industrial, coal-combustion, natural, and traffic-related inputs. The combined application of PMF and Pb/Cd isotopes allowed for constraints on heavy metal sources at both regional and local scales, providing a scientific basis for pollution control and agricultural safety management in paddy soils of the Yellow River irrigation district. Full article

Located in the northeastern Tibetan Plateau, the Qaidam Basin hosts abundant strategic lithium (Li) and boron (B) salt lake resources crucial for national resource security. Existing studies focus on individual lakes, lacking systematic Li-B geochemical and source–transport–sink research across the geothermal–river–lake system. Based on 40 water samples from 16 lakes and multi-isotope and hydrochemical data, this study explores Li-B spatial distribution, isotopic evolution and enrichment rules. The results reveal prominent spatial heterogeneity of Li and B distributions. The contents of riverine Li and B are higher than the global average level, and terminal salt lakes show the highest enrichment degree. Specifically, southern lakes are Li-dominant, while northern lakes are B-dominant, with both reaching industrial exploitation grades. Significant Li and B isotopic fractionation occurs throughout the hydrological system, with geothermal fluids presenting depleted isotopic compositions and lake waters showing enriched features. H-O isotopic evidence and Gibbs diagram analysis indicate that surface waters in the basin are primarily recharged by atmospheric precipitation, and their hydrochemical compositions are jointly controlled by rock weathering and strong evaporative concentration, accompanied by distinct north–south hydrogeological zonation differences. Source analysis demonstrates that Li is mainly derived from high-temperature water–rock interactions of Li-rich volcanic and granitic rocks in the southern East Kunlun Mountains, whereas B originates from ultrahigh-pressure B-rich metamorphic rocks along the northern North Qaidam margin. The migration and accumulation sequence of Li and B follows the pathway: geothermal fluid emission → fluvial transportation → terminal lake enrichment. Evaporation and mineral precipitation are the dominant factors controlling elemental enrichment and isotopic fractionation. This basin-wide study supplements salt lake critical mineral metallogenic theories and guides efficient Li-B exploration and sustainable development. Full article

Geochemical and isotopic analysis of bitumen-lined transport container vessels, so called ‘torpedo jars’, from the Sasanian to Early Islamic period fort of Fulayj in Oman confirms the presence of two distinct compositional categories that can be matched to contemporary sources in different areas of southwest Iran. It appears that the bitumen used to line jars was extracted from different geographic areas, hinting at the existence of multiple production locations for this vessel class. In terms of the function of the jars, organic residue analysis provides a positive identification of biomarkers associated with the storage and transportation of red wine. These results provide the first published confirmation of the long-suspected association between torpedo jars and wine transportation from the core urbanised zone of the Sasanian and Early Islamic imperial heartlands towards the Persian Gulf and Indian Ocean maritime sphere. The results have added significance as the samples are derived from relatively accurately dated archaeological contexts spanning the period before and after the Islamic conquest. Full article

This article describes the mineralogical and geochemical features of the Marsyaty Mn–Fe sedimentary deposit in the Northern Urals (Russia). Oolitic ironstones of the deposit are localized in the Cenomanian coastal sandstones. Manganese ores (carbonate and carbonate–oxide types) lies within the Lower Paleocene siliciclastic sediments and are separated from the oolitic ironstone (iron oxide and iron carbonate types) by a polymictic gravelite bed. Authigenic Fe³⁺ oxyhydroxides (goethite and ferrihydrite), chamosite/berthierine and late siderite predominate in the ironstones; kaolinite, apatite, perhamite, calcite and dolomite are minor constituents. Rhodochrosite and rancieite are the major minerals of the manganese ore; Mn-dominated phyllosilicates (parsettensite? and caryopilite?) are rare. Both ore types contain authigenic glauconite, montmorillonite, sulfides (sphalerite/wurtzite, galena, and pyrite), gibbsite/boehmite and REE phosphates. Both ore types contain detrital quartz, ilmenite, zircon, monazite, epidote, titanite, muscovite and feldspars. The δ¹³C_carb value (VPDB) varies from −18.5 to −23.3 in both ironstone types and from −10.0 to −41.0 ‰ in the manganese ore. The negative C isotopic composition and numerous organic remains indicate the involvement of microbial processes in the formation of both types of carbonate ores. The Fe and Mn ores belong to one transgression–regression sedimentation cycle and formed consecutively during the evolution of the West Siberian basin. A unique feature of the Marsyaty deposit includes two ore formation stages within a limited area and over a relatively short geological period: the accumulation of (i) oolitic ironstones enriched in Mn first and then (ii) manganese ores only. Full article

Records of recent past climate provide an essential window into understanding how changing climate influences environments and ecosystems such as lakes, which provide essential resources and services. Sediment carbon and nitrogen chemistry can offer insight into productivity and biochemistry, and anoxic sediments in particular can often preserve short-term changes in these signals. We used a decade-long compilation of sediment and environmental data from Middle Island Sinkhole, an anoxic sinkhole in Lake Huron, to investigate their interannual variability. We found that seasonal and annual changes in local ice season, chlorophyll, and precipitation influenced the amount and isotopic composition of carbon reaching and being recycled within the sediments. Carbon and nitrogen signals reflected the year or season of sample collection in sediments as deep as 12 cm, while the shallowest sediments were dominated by the influence of microbial mats. Our findings demonstrate that seasonal dynamics in surface water in this part of the Great Lakes are leading to increased export of organic carbon and nitrogen into sediments, but that in situ sediment processes may make teasing out short-term changes from sediment cores difficult even in an anoxic setting. These results emphasize the importance of winter conditions as a driver of short-term lacustrine carbon and nitrogen cycling in sediments and the water column. Full article

Geothermal energy is a low-carbon baseload renewable energy that plays a key role in global energy transition. Jinlun of Taitung is a region with high potential for geothermal energy. However, sustainable resource utilization requires a comprehensive understanding of fluid sources, recharge mechanisms, and circulation systems. This study integrated δ¹⁸O, δD, ⁸⁷Sr/⁸⁶Sr and elemental geochemistry to clarify the underlying hydrogeochemical mechanism and develop an underground fluid circulation model for Jinlun. The water compositions indicate that water–rock interactions are the dominant control on fluid chemistry. Hydrogen and oxygen isotope analysis revealed a geothermal water recharge elevation of 1321–1478 m, slightly higher than that of hot spring water (951–1459 m). The natural recharge amount of a corresponding area was approximately 13.57 × 10⁶ t/yr. A strontium isotope mixing model indicated that the fluids were affected by three end members of deep geothermal water, shallow groundwater, and seawater. Shallow groundwater had a contribution rate of 92–98% to noncoastal hot spring water and up to 81% to geothermal water. The coastal hot spring was most affected by seawater at 48%. Rainwater infiltrated into E2 to form shallow groundwater. Some of the infiltrated water reached a deep circulation into the M3 layer and formed deep-source thermal water. Overall, this study establishes a hydrogeochemical model for Jinlun and provides scientific foundation for geothermal well design and sustainable resource management. Full article

The development of sustainable and climate-resilient food systems increasingly relies on robust analytical methodologies capable of integrating environmental, biochemical, and management-related signals. In this study, a multi-isotope framework based on δ²H, δ¹⁸O, δ¹³C, and δ¹⁵N was applied to assess its capacity to discriminate between contrasting raspberry production systems and to provide chemically grounded indicators of agroecosystem functioning. Raspberry fruits (Rubus idaeus L.; cultivars Opal and Delniwa) were collected during the 2024–2025 growing seasons from two distinct systems in Romania: an organic open-field system and a rainfed agroforestry system. Stable isotope ratio analysis revealed system-dependent isotopic patterns, with the strongest differentiation observed for δ¹⁵N. Nitrogen isotope composition (δ¹⁵N) provided the strongest discrimination, with enriched values in organic fruits (2.73–9.77‰) and depleted values in agroforestry fruits (−3.01 to 0.62‰), reflecting differences in nitrogen sources and cycling pathways. Hydrogen and oxygen isotopes (δ²H: −60.46 to −4.62‰; δ¹⁸O: −6.19 to 10.41‰) were consistent with hydroclimatic variability and evaporative fractionation processes associated with soil–plant–atmosphere interactions. Carbon isotopes (δ¹³C: −28.14 to −22.62‰) provided complementary insights into plant water-use conditions. Multivariate statistical analysis supported the separation between production systems, while short-term fertilisation effects were secondary to system-level controls. The results suggest that raspberry fruits preserve an integrated isotopic fingerprint of production environment and management practices. From an analytical chemistry perspective, this work highlights the relevance of multi-isotope approaches as transferable tools for food authentication, traceability, and sustainability assessment, contributing to the broader application of stable isotope techniques across complex biological systems. Full article

To investigate the long-term water use efficiency (WUE) and ecological adaptation strategies of seven endangered Ormosia plant species, and to identify superior tree species with strong drought resistance, thereby providing a scientific basis for ecological restoration, represented the objectives of this research. This study focused on Ormosia semicastrata, Ormosia pinnata, Ormosia fordiana, Ormosia xylocarpa, Ormosia glaberrima, Ormosia emarginata and Ormosia henryi. Using these seven Ormosia species as subjects of study, and the commonly planted afforestation species Michelia macclurei and Castanopsis hystrix as controls, we determined long-term water-use efficiency by measuring stable carbon isotope (δ¹³$C$) values of the leaves. This was combined with growth indices and chlorophyll content; a systematic analysis was conducted of interspecific differences and similarities with the afforestation species, to reveal the ecological adaptability and survival potential of Ormosia plants in arid environments. Methodologically, leaf carbon isotope (δ¹³$C$) values were measured for each tree species to estimate long-term water use efficiency, whilst growth indices and chlorophyll content were also determined to compare differences between Ormosia plants and the control species. The results indicate that the leaf carbon isotope (δ¹³$C$) values of the seven Ormosia species ranged from −31.88‰ to −29.03‰. Among these, O. xylocarpa, O. pinnata and O. emarginata exhibited higher leaf carbon isotope (δ¹³$C$) values and water use efficiency, suggesting greater water utilisation capacity and drought tolerance; whereas O. fordiana and O. glaberrima exhibited lower values for both parameters. Chlorophyll analysis revealed that the total chlorophyll content of O. pinnata and O. fordiana was significantly higher than that of Michelia macclurei and Castanopsis hystrix, and the chlorophyll a to chlorophyll b ratio of all Ormosia species was higher than that of the afforestation tree species, suggesting greater photosynthetic capacity and adaptability to high-light environments. Furthermore, leaf carbon isotope (δ¹³$C$) values showed a highly significant positive correlation with water use efficiency, validating the reliability of carbon isotopes in assessing long-term water use efficiency in plants. Taking all indicators into account, O. xylocarpa and O. pinnata demonstrated good root development and efficient allocation of photosynthetic pigments whilst maintaining high water use efficiency; they are therefore considered excellent tree species that combine drought resistance with growth potential. By integrating growth, photosynthetic and water-use characteristics, this study has clarified the water-adaptation strategies of different Ormosia species, providing a scientific basis for selecting drought-tolerant Ormosia species and for ecological restoration. Full article

This study presents an assessment of the hydrodynamic connectivity and compartmentalization of petroleum reservoirs in the Caspian Basin using integrated oil fingerprinting and biomarker geochemistry approaches. The aim of the study was to identify inter-reservoir fluid communication, reconstruct hydrocarbon migration pathways, and determine the factors controlling the geochemical heterogeneity of reservoir systems. The investigation was based on the analysis of 43 oil samples collected from 15 fields within the Caspian Basin using gas chromatography, gas chromatography–mass spectrometry, carbon isotope analysis, and multivariate statistical methods, including principal component analysis (PCA) and hierarchical cluster analysis. The results revealed the presence of both hydrodynamically connected reservoirs characterized by similar molecular and biomarker compositions and compartmentalized reservoir blocks showing significant geochemical differences and variations in thermal maturity. It was established that the internal heterogeneity of the reservoirs is controlled by tectonic segmentation, multi-stage hydrocarbon migration, and differences in source rock characteristics. The obtained results confirm the effectiveness of oil fingerprinting methods for diagnosing hydrodynamic connectivity and reservoir compartmentalization in complex petroleum systems. Full article

Honey is a high-value food product that is vulnerable to adulteration with exogenous sugars, posing challenges for food authenticity and consumer protection. This study applied Stable Isotope Ratio Analysis (SIRA) to assess the authenticity of honey collected from three major honey-producing regions of Ghana (Volta, Bono and Bono East). A total of 28 honey samples were analysed by elemental analysis–isotope ratio mass spectrometry (EA-IRMS) to obtain carbon (δ¹³C), nitrogen (δ¹⁵N) and sulphur (δ³⁴S) isotope composition. Honey authenticity was evaluated according to AOAC Official Method 998.12 by comparing δ¹³C values of bulk honey and the corresponding protein fraction. The δ¹⁵N and δ³⁴S values in honey protein were used to investigate environmental and regional variability. Samples without detectable C4 adulteration exhibited δ¹³C_protein values consistent with C3 floral sources, whereas several samples showed Δδ¹³C values more negative than −1.0‰, indicating the presence of C4-derived sugars above the AOAC adulteration threshold. Calculated C4 sugar contents ranged from 8 to 12% in moderately adulterated samples to as high as 78–79% in severely adulterated samples, confirming substantial dilution with C4 sugars. Nitrogen and sulphur isotope ratios provide additional information on environmental and regional variability among the sampled regions. Principal Component Analysis revealed that the first two principal components (PC1 and PC2) accounted for 83.8% of the total variance 83.8% of the total variance and showed separation between samples with detectable C4 adulteration and those without, while highlighting regional isotopic differences. These results demonstrate that stable isotope analysis is an effective tool for detecting C4 sugar adulteration in honey and that the combined use of carbon, nitrogen and sulphur isotopes can provide additional information on environmental and regional variability. These findings provide preliminary isotopic data on honey collected from three major honey-producing regions of Ghana and support the application of the stable isotope approach for honey authenticity assessment and quality control. Full article

Peak annotation in Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a persistent bottleneck that typically requires the manual assignment of chemical formulas to hundreds of fragment ion peaks per spectrum. This work describes a physics-informed probabilistic framework that automates this task by combining five chemically motivated constraints—Gaussian mass accuracy, element composition priors, isotope pattern matching, nitrogen rule parity, and graded valence bounds—into a multiplicative belief score. We evaluate the framework on 643 ground-truth peaks from 151 compounds spanning both positive and negative ion modes, and we explicitly distinguish two regimes. As a scoring task—when the correct formula is present in the candidate list—the framework attains 52.3% Top-1 and 76.4% Top-3 accuracy, a 4.9-fold improvement over mass-only scoring. In fully automated end-to-end deployment, where candidates are generated de novo, Top-1 accuracy is 26.3%; the limiting factor is candidate generation rather than scoring, as only 46.5% of ground-truth formulas are currently produced by the database and combinatorial generator. Leave-One-Compound-Out Cross-Validation (59 compounds, 525 peaks) yields 51.8% Top-1 accuracy with fixed domain-knowledge weights, confirming generalization stability. Ablation analysis identifies element composition priors as the dominant non-mass constraint (−27.7 percentage points when removed), followed by isotope matching (−10.3 pp) and the nitrogen rule (−5.3 pp). The framework requires no labeled training spectra—relying instead on physically motivated priors and curated fragment databases—provides interpretable per-constraint scores (which represent relative rankings rather than calibrated probabilities), and supports polarity-specific configurations, offering a practical computational foundation for automated ToF-SIMS spectrum interpretation. Full article

Yttrium-90 (⁹⁰Y) is a pivotal pure beta-emitting radionuclide extensively employed in the targeted therapy of malignant tumors, such as hepatocellular carcinoma and lymphoma. The ⁹⁰Sr-⁹⁰Y generator system represents the most effective method for producing no-carrier-added (NCA) ⁹⁰Y to meet escalating clinical demands. However, safe clinical application necessitates the stringent separation of its parent isotope, ⁹⁰Sr, which poses significant radiotoxicological risks due to its long half-life and bone-seeking behavior. This review comprehensively summarizes recent advances in solid-phase adsorbent materials developed for the high-efficiency separation of Y³⁺ and Sr²⁺. We systematically analyze the design strategies, molecular recognition mechanisms, and performance evaluation metrics of various functional systems. Key materials discussed include extraction chromatography (EXC) resins based on organophosphorus extractants, diglycolamide (DGA) derivatives, and crown ethers, as well as inorganic ion exchangers such as antimony-based materials, manganese oxides, and zeolite-like molecular sieves. Special attention is given to composite modification strategies, including silica-based and polymer-matrix composites, and metal doping techniques aimed at enhancing radiation resistance, acid stability, and Sr-Y separation factors (SF). Finally, we provide an outlook on the future development of next-generation ⁹⁰Sr-⁹⁰Y generator materials, highlighting the imperative of transitioning from idealized simulated environments to robust, field-ready applications. Full article

Understanding evapotranspiration (ET) partitioning into soil evaporation (E) and plant transpiration (T) is crucial for improving agricultural water use efficiency in water-scarce regions. The isotope mass balance (IMB) method and AquaCrop model are two widely used approaches for ET partitioning, yet their comparative performance across different crop growth stages remains poorly characterized. This study systematically compared these two methods using two consecutive years (2012–2013) of field isotopic observations in a summer maize field on the North China Plain, a core maize production area facing severe agricultural water scarcity. Stable isotope analysis showed that the local meteoric water line (LMWL) had a slope lower than the global meteoric water line. The 0–5 cm surface soil water evaporation lines had slopes of 5.84 (2012) and 8.06 (2013), confirming significant evaporative enrichment in the topsoil. Plant water isotopic composition closely resembled that of 40–100 cm deep soil water, indicating limited root uptake from the surface layer. IMB-estimated transpiration ratio (T/ET) exhibited distinct phenological patterns, increasing from 37 to 44% at jointing to a peak of 94–96% at filling, then declining to 84–85% at maturity. The two methods agreed well during filling to maturity (differences of 2–10%), but compared with the IMB method, AquaCrop substantially underestimated T/ET at jointing (0.9% vs. 43.8% in 2013) due to its canopy-cover-based transpiration algorithm. These findings identify the filling stage as the critical water demand period, providing a quantitative reference for precision irrigation management under similar climate and soil conditions. Full article

The Shiganghe tungsten–tin deposit and the Tiechang tin deposit are located in the northern part of the Baoshan Block, approximately 25 km apart. They were formed in the Late Cretaceous and Early Oligocene, respectively, and exhibit distinct deposit characteristics. This study presents a comparative analysis of in situ trace elements and S-Pb isotopes of pyrite from the two deposits to trace the sources of ore-forming fluids and materials and to further constrain the evolution of the metallogenic setting in the Baoshan Block. The trace element compositions of pyrite from the Shiganghe tungsten–tin deposit differ significantly from those of the Tiechang tin deposit. The former is relatively enriched in Se, Al, and W, while the latter contains relatively high concentrations of Cu, As, Sb, Pb, Bi, and Ag. The sulfur isotopic compositions of pyrite from the Shiganghe deposit are lower than those from the Tiechang deposit, with δ³⁴S_CDT values ranging from 2.11‰ to 6.86‰ and 6.74‰ to 8.72‰, respectively. The two deposits share consistent lead isotopic ratios, characterized by a mixture of upper crustal and orogenic belt sources. Therefore, the mineralization of the Shiganghe tungsten–tin deposit may be related to deep seated, concealed Late Cretaceous magmatism. Relatively oxidized and W-rich magmatic fluids contributed to tungsten–tin mineralization that characterized by a zoning pattern of “tungsten above and tin below”. In contrast, the Tiechang tin deposit is likely associated with coeval leucogranites present in the shear tectonic zone near Caojian. The ore-forming fluids underwent long distant migration with extensive crustal contamination, resulting in a relatively reduced hydrothermal system. Combined with the regional geological setting, the mineralization of the Shiganghe tungsten–tin deposit and the Tiechang tin deposit records the geological event from Neo-Tethys Ocean subduction to the collisional orogeny between the Indian and Eurasian blocks. The ore-forming materials originated from a mixture of upper crustal materials and orogenic belt materials. Full article