Search Results (569)

Astrobiological observations usually return atmospheric, mineralogical, molecular, isotopic, or textural states rather than organisms. The interval between environmental habitability and confirmed life detection is therefore an evidential problem. This article develops planetary geochemical metabolism (PGM) as a scale-explicit description of abiotic water–rock–fluid reactions, including atmospheric or ice-shell boundary conditions where relevant, that sustain redox disequilibria, catalytic mineral interfaces, prebiotic molecular fluxes, and preservable mineral products. Proto-biosignatures are defined as contextual, non-diagnostic signatures of this interval: signals that do not demonstrate life, but increase the plausibility of prebiotic network organization relative to low-organization abiotic chemistry. A nondimensional Geochemical Metabolic Potential, ${\Phi }_{\mathrm{PGM}}$, is formalized as a target-specific screening index describing redox exergy, catalytic-interface density, reaction-network closure, environmental cycling efficacy, and preservation potential. The index is not calibrated as a probability of life. A reproducible Latin-hypercube experiment across $M_{\mathrm{sim}}=5000$ synthetic environments examines internal model behavior rather than ranking planets. Higher ${\Phi }_{\mathrm{PGM}}$ values mark hypotheses to be tested under declared scale, uncertainty, and observability constraints. Applications to early Earth, Noachian Mars, ocean worlds, and terrestrial exoplanets illustrate that habitability, prebiotic organization, biological inference, and preservation are distinct quantities. Full article

This study elucidated the spatial distribution characteristics of surface snow chemistry and stable isotope composition and their influencing factors in Antarctica’s coastal region. We analyzed data from eight surface snow chemical ion transects and five surface snow stable isotope transects to examine the distributions of sea-salt ions (Na⁺, Cl⁻, Mg²⁺, K⁺), non-sea-salt ions (NO₃⁻, methanesulfonic acid (MSA), non-sea-salt sulfate (nssSO₄²⁻), non-sea-salt Ca²⁺ (nssCa²⁺)), and the stable isotope δ¹⁸O. Concentrations of chemical ions were found to exhibit distinct source signatures. Principal component analysis indicated that the ranking of ion sources in Antarctica’s coastal areas is as follows: sea-salt aerosol transport, followed by marine biological activities and crustal dust and then atmospheric chemical reactions. Data from all transects exhibited a general pattern of diminishing δ¹⁸O with increasing distance from the coast but with marked regional differences in the δ¹⁸O–distance slope (−6.84 to −1.98‰/100 km), δ¹⁸O–altitude slope (−0.97 to −0.20‰/100 m), and δ¹⁸O–temperature slope (0.61 to 1.14‰/°C). The moisture source regions and transport pathways, local orographic uplift, and local temperature field jointly affect the differentiation of δ¹⁸O in coastal areas. The findings suggest that snow chemistry and isotopic composition in Antarctica’s coastal zones are controlled by marine source transport, biogeochemical cycling, and polar topographic and climatic processes. Full article

The southern Zhuguangshan complex is one of the most important sources of granite-hosted uranium deposits in the Nanling region and consists predominantly of Caledonian (Cambrian–Silurian), Indosinian (Late Permian–Triassic), and Yanshanian (Jurassic–Cretaceous) granitoids. However, the Caledonian plutonic rocks have not yet been systematically investigated. In this study, we present new LA-ICP-MS zircon U–Pb ages and Hf isotopes, together with whole-rock elemental and Sr–Nd isotope data, for the Guantian and Shangbao granodiorites from the southern Zhuguangshan complex, in order to constrain their petrogenesis and tectonic setting. Zircon U–Pb dating yields emplacement ages of ca. 431.5 and 442.3 Ma for the Guantian and Shangbao plutons, respectively. Both plutons are characterized by high Al₂O₃ (14.35–14.77 wt.% and 13.55–14.38 wt.%) and total alkali (Na₂O + K₂O = 6.22–6.82 wt.% and 6.46–6.85 wt.%) contents, with A/CNK ratios <1.0, and are classified as metaluminous I-type granites. They show enrichment in light rare earth elements (LREE), K, Th, and U, coupled with marked depletion in Ba, Sr, Nb, Ta, P, and Ti, and exhibit pronounced negative Eu anomalies. These geochemical signatures indicate fractional crystallization of Ti-bearing minerals (e.g., rutile and ilmenite) and plagioclase. The granodiorites have initial ⁸⁷Sr/⁸⁶Sr ratios of 0.70595–0.71227, negative εNd(t) values (−7.8 to −4.1), and negative εHf(t) values (−8.7 to −0.4), pointing to a dominantly continental crustal source. Their average Nb/Ta (11.42) and Th/U (5.07) ratios are also consistent with typical continental crust. Based on the lithological assemblage and geochemical characteristics, we propose that the Guantian and Shangbao granodiorites were formed in a post-collisional extensional setting. Full article

Groundwater is a critical resource for domestic, agricultural, and industrial use in the Gilgel Gibe and Dhidhessa catchments of southwestern Ethiopia, where volcanic aquifer systems are the main sources. However, groundwater quality in these catchments has been under pressure from anthropogenic activities such as population growth, land-use changes, and pollution driven by rapid development and poor resource management. This study investigates hydrogeochemical processes and evaluates groundwater quality in volcanic aquifers using hydrochemical analyses and a stable isotope approach applied to 115 water samples. The spatial distribution of various physicochemical and hydrogeochemical parameters shows a distinct contrast between the highland and lowland regions, indicating topography-driven variations in water quality and geochemical processes. In hand-dug wells, springs, and surface waters, the ionic order is Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ and HCO₃⁻ > NO₃⁻ > Cl⁻ > SO₄²⁻, whereas deep wells show Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and HCO₃⁻ > Cl⁻ > SO₄²⁻ > NO₃⁻. The predominant groundwater type is Ca-HCO₃, followed by Na-HCO₃ and Ca-NO₃, with other types including Ca-Mg-HCO₃, Ca-Na-HCO₃, and Na-Ca-HCO₃. Water types of Ca-HCO₃ and Ca-Mg-HCO₃ dominate the upland areas, indicating relatively young groundwater with moderate total dissolved solids (TDSs) and enrichment in δ¹⁸O and δ²H, where highly mineralized Na-HCO₃ water types prevail in the deep aquifers of the lowland regions, where δ¹⁸O and δ²H are relatively depleted. Principal component analysis, cross-plots of major cations versus HCO₃⁻, and mineral stability diagrams indicate that aluminosilicate weathering and dissolution are the dominant processes controlling groundwater chemistry in the study area. The higher saturation index values observed in the deep wells indicate water closer to mineral equilibrium, suggesting more extended water–rock interaction relative to the shallow wells. The CO₂ partial pressures calculated using PHREEQC exceed atmospheric levels (~10^−3.5 atm), indicating sources from atmospheric influx, soil, or biogenic activity for most samples, and deeper sources such as mantle degassing may be found in a few deep wells. Scatter plots of Cl⁻ vs. SO₄²⁻ and Cl⁻ vs. NO₃⁻, associated with Ca(NO3)₂, NaNO₃, and CaCl₂ water types, suggest that anthropogenic inputs are the second major factor influencing the area’s water chemistry. Stable isotope analyses and hydrochemical data indicate that groundwater in the area primarily originates from local precipitation, with isotopic signatures reflecting strong groundwater–surface water interaction. These findings improve understanding of regional hydrogeochemistry and groundwater quality and help identify promising zones for sustainable groundwater development. This study provides valuable insights into groundwater resource management both in the study area and in regions sharing comparable geological contexts. Full article

Modern scientific research approaches to studying the hydrological cycle of water in nature, in addition to the mathematical modeling of hydrological–hydraulic processes that have expanded in recent years, increasingly include isotope hydrology on a global scale. This paper presents the preliminary results of research in the Vardar River Basin. The research is in the field of isotope hydrology with the analysis of stable isotopes of hydrogen (δ²H) and oxygen (δ¹⁸O) in precipitation (P), surface water (SW) and groundwater (GW). For this purpose, a network for taking water samples in the Vardar River Basin has been established. The isotopic composition of precipitation shows a relatively wide variability, with δ²H values ranging from −83.7‰ to −12.4‰ and δ¹⁸O values from −11.65‰ to −2.99‰. In contrast, groundwater samples exhibit a considerably narrower isotopic range, with δ¹⁸O values between −10.98‰ and −10.1‰ and δ²H values between −73.3‰ and −68.1‰. Surface water samples show δ¹⁸O values ranging from −10.7‰ to −9.11‰ and δ²H values from −70.6‰ to −61.6‰. The results of the study show that the waters in the Vardar River Basin are predominantly of meteoric origin, with their isotopic composition being strongly influenced by climatic factors and altitude, varying from approximately 1400 m and 2000 m a.s.l. The study confirms that precipitation is the primary source of both surface and groundwater. Evaporation is the dominant process that modifies isotopic signatures during rainfall, surface runoff and groundwater recharge. Due to good fit and nearly parallel meteoric lines observed in the three different locations, preliminary LMWLs and RMWL were estimated. A similar isotopic composition of surface water (SW) and groundwater (GW) in some locations indicates the presence of a direct and active hydrological connection between these water bodies, which need to be investigated in more detail in future research. However, one of the groundwater sampling locations suggest more depleted isotopic composition, which is probably related to different recharge altitudes, but also possibly very interesting relationship between Vardar River, alluvial aquifers and karst aquifer in the Žeden massif. Full article

The newly discovered Caijiagou gold deposit is hosted in metasedimentary rocks of the Silurian Taiyangsi Formation in the West Qinling Orogen (WQO), central China. Three mineralization stages are recognized: (1) the quartz–sericite–pyrite stage (Stage I), characterized by fine-grained, disseminated pyrite (Py1) and arsenopyrite (Apy1) with trace amounts of native gold; (2) the main ore-stage, the quartz–polymetallic sulfide–ankerite stage (Stage II), which contains coarse-grained euhedral pyrite (Py2) and arsenopyrite (Apy2) intergrown with ankerite and native gold; and (3) the post-ore calcite stage (Stage III), which is barren. Hydrothermal alteration assemblages include silicification, sericitization, pyritization, and carbonatization. In situ trace element analyses show that gold is mainly hosted in Py2 (avg. 2.86 ppm Au) and Apy2 (avg. 1.95 ppm Au), with consistently low Co/Ni ratios (<0.6) in ore-stage sulfides, supporting a metamorphic fluid origin. Sulfur isotope values (δ³⁴S = +6.47‰ to +11.96‰) point to sulfur derived from thermochemical reduction of marine sulfate. Apatite from the main ore stage (Stage II) yields a U–Pb lower intercept age of 237 ± 4.3 Ma (MSWD = 0.89), placing the mineralization in the Middle Triassic (Indosinian orogeny). These results are consistent with a sediment-hosted orogenic gold model, and the geochemical and geochronological signatures provide insights into the ore-forming process and regional metallogeny of the WQO. Full article

Regional multi-isotope mapping provides an effective means of investigating deep crustal composition and crustal reworking processes. The western margin of the Yangtze Craton has experienced multiple episodes of magmatism, crustal reworking, and mineralization since its formation, making it an ideal region for exploring the relationship between deep crustal evolution and metallogenic systems. In this study, Sr-Nd-Hf isotopic and whole-rock geochemical mapping was conducted based on compiled geochronological, geochemical, and isotopic datasets, integrated with deep geophysical data, to reconstruct the Precambrian crustal composition and reworking processes of the region. The results reveal significant crustal heterogeneity in the western margin of the Yangtze Craton. West of the Anninghe Fault Zone, rocks exhibit depleted Nd-Hf isotopic signatures (ε_Hf(t) = 0 to +17; ε_Nd(t) = 0 to +6), low I_Sr values (0.702–0.710), and high Nb/Ta (14–26) and Zr/Hf (36–46) ratios, indicating derivation from the remelting of juvenile mafic lower crust and providing direct evidence for Proterozoic underplating of mantle-derived magmas. In contrast, rocks east of the Anninghe Fault Zone show enriched Nd-Hf isotopic signatures (ε_Nd(t) = −9 to 0; ε_Hf(t) = −7.5 to 0), higher I_Sr values (0.711–0.726), and lower Nb/Ta and Zr/Hf ratios (8–13 and 21–35), suggesting remelting of ancient continental crust. Mineralization is closely associated with crustal architecture. IOCG deposits mainly occur in juvenile crustal domains, whereas Sn polymetallic and phosphate deposits are associated with ancient reworked crust. Under the Precambrian subduction setting, continuous arc magmatism promoted juvenile crust growth, whereas asthenospheric upwelling facilitated ancient crustal reworking, jointly controlling the spatiotemporal distribution of metallogenic systems along the western margin of the Yangtze Craton. Full article

The present work focuses on investigating U–Pb and Lu–Hf ages of zircon grains obtained from Au mineralized granitic rocks from Alta Floresta Gold Province (AFGP), in the Amazonia craton, Brazil. Also, detrital zircon grains from recent Au-rich sediments were analyzed for U–Pb ages and Lu–Hf isotopic signatures to apply to regional gold exploration in the AFGP to define targets consisting of deep-seated mineralized bodies using isotopic tracers. U–Pb ages of magmatic rocks, obtained from zircon grains, indicate crystallization ages ranging from 1896 Ma to 1825 Ma for rocks associated with gold deposits, and TDM model ages between 2.65 and 1.96 Ga and εHf values between +8.0 and −4.6. U–Pb ages obtained from 89 detrital zircon grains indicate peaks at 2055–1980 Ma, 1889–1985 Ma, 1790–1700 Ma, and 1600–1550 Ma. The first group is related to the basement, represented by the rocks of the Cuiu-Cuiu Complex (TDM 2.0–1.9 Ga and εHf from +8.7 to −1.32). The second group concerns the mineralized magmatic rocks in the AFPG, and the ages range from 18,896 to 1825 Ma, TDM ages ranging from 2.90 to 2.75 Ga, and the εHf values from +15 to −8. The age ranging from 1790 to 1700 is associated with anorogenic magmatism (TDM 2.0–1.9 Ga and εHf from +5.36 to −8.46). The youngest group comprises ages from 1600 to 1550 Ma, probably correlated to the Serra da Providencia suite with TDM of 1,6 to 1,50 Ga and εHf from +5,0 to −10. In this way, it was possible to identify the age range of detrital zircon grains concerning the ages of mineralized granites and characterize the Hf signatures associated with the mineralization processes. In this sense, the zircon grains associated with the magmatic processes responsible for the concentration of noble metals exhibited U–Pb ages and ε_Hf values interpreted as having been generated in magmas originating from a depleted mantle. As suggested in the literature, the magma characteristics reported here are coherent with a hot, hydrous, Fe-rich, high-K calc-alkaline, and subvolcanic emplacement. Based on the model that correlates gold deposits with porphyritic magmatic processes, significant discoveries with world-class volumes may result from better characterization of the deposit types found in the province. Full article

Stepwise functionalization of graphene oxide (GO) into polymerizable derivatives requires analytical evidence able to distinguish chemical modification from the spectral overlap typical of oxidized carbon frameworks. Here, pristine GO, amine-functionalized GO (GO–ED), and the methacrylamide-modified derivative GRAPHYMERE^® were compared by elemental analysis and stable isotope ratio mass spectrometry. Carbon content increased progressively from GO to GRAPHYMERE^®, while nitrogen was reproducibly incorporated after amination and retained after methacrylamide modification. The materials also showed a monotonic δ¹³C shift and distinct δ¹⁵N signatures for the nitrogen-containing derivatives, consistent with progressive bulk chemical modification. These elemental–isotopic trends provide complementary support for the proposed functionalization pathway and for the analytical distinction among the starting material, intermediate, and final derivative. EA–IRMS is therefore proposed as an additional batch-screening tool for chemically complex GO-based precursors intended for future polymeric and dental-material applications, without replacing bond-specific structural techniques. Full article

The Yishu Fault Zone (YSFZ) is located in a key tectonic transition zone shaped by the interaction between the Pacific and Tethyan tectonic domains in eastern China. Despite sparse geothermal borehole coverage across this region, the deeply incised fault structures create favorable hydrogeological prerequisites for fault-mediated subsurface heat migration and hydrothermal fluid circulation. This study integrates hydrochemistry, multi-isotope tracing (δD, δ¹⁸O, ⁸⁷Sr/⁸⁶Sr, and δ³⁴S), multi-mineral equilibrium modeling, and silica–enthalpy mixing analysis to constrain the evolution process and genetic mechanism of geothermal groundwater in the middle segment of the YSFZ. The geothermal groundwater displays weakly alkaline to alkaline properties and in situ temperatures of 35.2~75.0 °C, which is characterized by the HCO₃–Na, SO₄–Na, and Cl·SO₄–Na type. Stable isotope signatures demonstrate that the geothermal groundwater is recharged by the atmospheric precipitation with elevations of 822~1274 m. The hydrochemical evolution of the geothermal waters is governed by silicate weathering, evaporite dissolution, and cation exchange. The ⁸⁷Sr/⁸⁶Sr ratios indicate mixed solute contributions from silicate and evaporite lithologies, whereas the δ³⁴S signatures suggest that SO₄²⁻ is predominantly derived from gypsum dissolution. Two distinct hydrochemical evolution patterns can be identified in the study area. Samples GG1 and GG5 are characterized by HCO₃⁻ enrichment, whereas GG2, GG3, and GG4 exhibit enrichment in Na⁺ and SO₄²⁻. Reservoir temperatures estimated using multi-mineral equilibrium geothermometry range from 56.7 °C to 92.1 °C, with circulation depths of 1648~2304 m and cold-water mixing ratios of 48%~69%. The results of this study provide geochemical evidence for hidden geothermal resource exploration in deep fault zones. Full article

The common products of acidogenesis, the key stage in the process of anaerobic digestion, are lactate, butyrate, propionate, and acetate. They were decomposed in the Up-flow Anaerobic Sludge Blanket bioreactors working in continuous-flow open systems. A comprehensive analysis of variations in both isotopic ratios and concentrations of organic acids in the effluents was conducted to enhance comprehension of methanogenic processes. The analysis of carbon isotope fractionation in the CO₂-CH₄ system, as evidenced by the α¹³C_CO2-CH4 factor, has indicated that acetate decarboxylation has occurred. Furthermore, a decline in CO₂ levels was observed, accompanied by the predominance of butyrate and propionate, despite the presence of acetic acid in the effluents from all the bioreactors. Butyric acid demonstrated the greatest resistance to decomposition, resulting in ¹³C-enrichment of DIC. Lactic acid was utilised almost entirely. The observations presented above were subsequently validated through statistical analysis. A comparative analysis of the δ¹³C(CH₄) and δ¹³C(CO₂) values of our study with those of other natural substrates (detritic lignite, xylite, maize silage, and cattle manure) was undertaken, and it was found that isotope fractionation differs significantly in closed (potential thermodynamic processes) and open systems (expected Rayleigh processes). In the context of open systems, the isotope fractionation factor α¹³C_CO2-CH4 during methaneogenesis has been observed to attain values that are consistent with those observed in CH₄ oxidation. The study revealed that the presence of acetate in the substrate (i.e., the M4 bioreactor) led to the generation of CO₂ with a higher proportion of light carbon isotopes. This, in turn, resulted in a shift in the isotope fractionation factor (i.e., α¹³C_CO2-CH4) to values below 1.03. Our results suggest that methanogenic pathway signatures in open, continuous-flow systems may only be partially apparent. This is because substrate depletion drives Rayleigh-type isotope enrichment, while the dominance of a single substrate and its constant inflow stabilise pathway expression and shift control towards substrate dynamics rather than intrinsic microbial changes. Our finding suggests that isotope-based diagnostics could enhance process control in biogas plants by identifying substrate-driven limitations and facilitating more efficient and stable CH₄ production. Full article

Background/Objectives: Oral squamous cell carcinoma (OSCC) remains clinically heterogeneous, and prognosis is not always fully explained by conventional clinicopathological parameters. Systemic inflammation and tumor metabolic alterations may provide complementary information on tumor biology. This study aimed to assess associations between preoperative inflammatory markers, isotope ratio mass spectrometry (IRMS)-derived tumor signatures, clinicopathological features, and survival outcomes in OSCC. Methods: This exploratory retrospective secondary analysis included 50 consecutive patients with surgically treated, histologically confirmed OSCC. Preoperative blood-based markers, including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), white blood cell count, lymphocyte count, and C-reactive protein, were retrieved from routine laboratory tests. Matched tumor, surgical margin, and healthy oral mucosa samples were analyzed by IRMS for δ¹³C, δ¹⁵N, carbon and nitrogen content, and [N]/[C] ratio. Associations with clinicopathological variables, nodal status, overall survival (OS), and disease-free survival (DFS) were evaluated using non-parametric tests, Spearman correlations, and Cox regression models. Results: Tumor tissue showed a consistent isotope and elemental phenotype compared with healthy mucosa, including higher nitrogen content, lower carbon content, increased [N]/[C] ratio, lower δ¹⁵N, and less negative δ¹³C values. NLR, PLR, SII, and CRP were not robustly associated with standard clinicopathological features after correction for multiple testing. Correlations between inflammatory and isotope-derived parameters were modest. Higher NLR was associated with worse OS and DFS and remained significant after adjustment for pathologic nodal status. Less negative tumor δ¹³C showed a potential adverse prognostic signal. Conclusions: Systemic inflammatory markers and IRMS-derived tumor signatures appear to reflect partly distinct biological domains in OSCC. NLR may provide accessible prognostic information, while tumor δ¹³C warrants further validation as a metabolic biomarker. Full article

Biogenic or microbial methane (CH₄) emissions, believed to be the main driver of the recent surge in global atmospheric CH₄ emissions, have altered monitoring, measurement, and mitigation of fossil-fuel emissions. As of 1981, over 20% of the world’s natural gas reserves were biogenic in origin. Additional biogenic CH₄ reserves from coal have been discovered since 1981 mixed (40–80%) with thermogenic CH₄. Biogenic CH₄ accumulates up to 100% in coal reservoirs in the Powder River Basin (PRB), USA. Biogenic CH₄ is generated by microbial breakdown of fossil organic matter as an early-stage (primary) type during burial over geologic time and is rarely preserved. Also, biogenic CH₄ is generated as a late-stage (secondary) type from recent geologic to present times and is commonly preserved. Late-stage biogenic CH₄ is sustained by nutrients and microbes in meteoric/surface waters discharged into coal aquifers. Groundwater is pumped from wells in coal aquifers to desorb and produce CH₄ and dewater coal mines. The co-produced water with dissolved CH₄ is discharged into diverse surface aquatic systems. The emission factors (EFs) of co-produced water are 2.0522 × 10⁻⁹ Gg CH₄/gal of water in the PRB and 2.0694 × 10⁻³ Gg CH₄/well in the Black Warrior Basin, U.S. Accurate data on biogenic CH₄ emissions from coal sources is a major gap in the accounting of current global groundwater-driven CH₄ whose average flux is estimated to be 3.9 ± 6.2 mmol/m²/day or accounting for up to 70% of CH₄ emissions from surface aquatic systems. Biogenic CH₄ emissions from coal mining and coalbed gas extractions and related infrastructures are overlooked because the focus has been on coalmine methane (CMM) emissions. CMM data from ground-based measurements is highly variable and used by the Intergovernmental Panel on Climate Change three-tier system to estimate EFs for national inventories. However, 90% of CMM emissions are attributable to a small group of the most coal-consuming-and-producing countries but fails to capture other coal sources worldwide. This created gaps and “blind spots” in “unstructured” low-concentration, diffused biogenic CH₄ emission data. These key “blind spots” include sources from flooded, abandoned coal mines; coalbed methane (CBM) co-produced water with dissolved CH₄ and infrastructures/facilities; and groundwater drawdown from water withdrawals during coal mining and CBM extraction. Also, a critical “blind spot” is the mixing of biogenic CH₄ emissions from subsurface coals with biogenic CH₄ generated at the surface from wetlands, agriculture, and landfills/wastes, which grew 85% from 2008 to 2020. Limited understanding of the mixing of biogenic CH₄ from diverse sources and their contributions to global methane requires accurate attribution of overlapping isotopic signatures (δ¹³C_CH4 and δD). This paper addresses knowledge gaps in coalbed biogenic CH₄ emissions by a systematic review of the literature and specific study cases, which provided insights on key “blind spots” in their mitigation. Full article

Informal electronic-waste (e-waste) dismantling can mobilize mercury (Hg) from Hg-containing components and contaminated dust, while local diet can contribute methylmercury (MeHg), creating a mixed environmental exposure setting for human biomonitoring. This pilot study integrated paired biomarkers, local foods, work and indoor dust, Hg speciation and hair Hg isotope signatures among 18 e-waste dismantling workers in Qingyuan, South China. Total Hg (THg), MeHg and inorganic Hg (IHg) were measured in hair, blood and foods; urine and dust were analyzed for THg; and hair δ²⁰²Hg, Δ¹⁹⁹Hg and Δ²⁰¹Hg were determined. Median THg was 403 μg/kg in hair, 1.60 μg/L in blood and 0.438 μg/L in urine. Fish showed the highest food THg, whereas work and indoor dust had the highest matrix concentrations. Hair was MeHg-dominant but contained substantial IHg, and Δ¹⁹⁹Hg values were positive but modest. The integrated patterns support mixed dietary MeHg and non-dietary IHg contributions and identify exposure-pathway priorities for future biomonitoring and source-focused studies. Full article

Lead isotope ratios are frequently used in archaeometric provenance analysis; however, the overlap of isotopic fields within the Andean metallogenic belt complicates reliable provenance determination. This study presents a reproducible fidelity-based kernel method for the unsupervised clustering of Andean lead-isotope data and investigates whether a quantum-mechanical similarity space can reveal geologically significant structures beyond the classical Euclidean partition. A dataset of 1522 measurements of ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb was analyzed using a fidelity-based quantum kernel based on a three-qubit Pauli feature map and compared with classical K-means clustering, Gaussian mixture models, and Ward’s agglomerative clustering under various preprocessing strategies and cluster counts. The optimal quantum kernel setup achieved the highest silhouette score at k = 2. However, because analytical uncertainties were not consistently reported across all the compiled sources, an uncertainty-weighted similarity could not be applied. Geological insights indicate that this binary division separates less radiogenic, arc-related compositions from more radiogenic and thorogenic crustal signatures, a contrast that broadly follows the west-to-east crustal-contamination gradient across the Andes. Conversely, the traditional four-cluster approach provides more detailed subdivisions that align with the previously identified isotopic provinces. The reported separation reflects the geometry of the quantum feature space rather than any hardware-level speed-up, as this work represents only a simulation approach. Overall, these findings support a hierarchical and complementary approach to analyzing Pb isotope origins, in which quantum kernel clustering provides robust large-scale separation and classical clustering enhances regional understanding. Full article