Search Results (6,204)

Background: Creatine deficiency syndromes (CDS) are rare neurometabolic disorders caused by defects in creatine biosynthesis (AGAT and GAMT deficiencies) or creatine transport (SLC6A8 deficiency). Early biochemical recognition is crucial for timely treatment of AGAT and GAMT deficiencies and for improving neurodevelopmental outcomes. In Morocco, expanding the liquid chromatography-tandem mass spectrometry (LC-MS/MS) biomarker panel for inherited metabolic disorders is a priority to strengthen diagnostic capacity and reduce diagnostic delay. Methods: We developed and validated a rapid LC-MS/MS method for the simultaneous quantification of creatine (Cr), guanidinoacetate (GAA), and creatinine (Crn) in plasma and urine using isotopically labelled internal standards and a standardized sample preparation procedure. Analytical performance, including linearity, precision, accuracy, sensitivity, matrix effects, carryover, inter-sample contamination, stability, and measurement uncertainty, was assessed in accordance with ISO 15189:2022 requirements. Results: The assay showed excellent linearity across the analytical range (r² > 0.99), with robust intra- and inter-day precision (CV < 10%). Limits of detection (LOD) were 0.05 µmol/L for Cr and 0.03 µmol/L for GAA in urine, and 0.05 µmol/L for Cr and GAA in plasma. The total run time was 1.1 min per sample, supporting high-throughput implementation. Method performance was further supported by satisfactory results in ERNDIM external quality assessment schemes. Preliminary internal reference ranges and expanded measurement uncertainty were calculated from the available anonymized dataset. Conclusions: This rapid LC-MS/MS method enables the measurement of key CDS biomarkers and contributes to expanding the LC-MS/MS biomarker panel for inherited metabolic disorders in Morocco. Full article

The Nam Xan gold deposit is located in the central Truong Son Fold Belt of Laos. It is a newly identified distal intrusion-related gold system (IRGS) in a continental arc setting. This study uses whole-rock geochemistry, Pb and S isotope systematics, and mineral-scale analyses to trace magmatic evolution and ore-forming processes. Whole-rock data indicate that the associated intrusive suite is a calc-alkaline volcanic-arc granite (VAG) series, derived from a subduction-modified mantle source with notable crustal contributions. Pb isotopes reveal mixing arrays rather than true isochrons. Monte Carlo modeling shows binary mantle–crust mixing for igneous rocks and ternary mixing with an additional radiogenic component in ore samples, indicating enhanced fluid–rock interaction during mineralization. Sulfur isotope data show a shift from magmatic sulfur (δ³⁴S ≈ −5‰) in early skarn-stage pyrite to heavier values (δ³⁴S ≈ +6‰) in gold-bearing stages, reflecting fluid evolution driven by cooling and redox changes. Mineral chemistry data demonstrate that gold is present both as invisible gold within arsenian pyrite and as free gold in late-stage fractures. Strong correlations between Au and As, along with elevated Co/Ni ratios and enrichments in Bi, W, and F, collectively support a magmatic-hydrothermal origin. These findings define a three-stage mineralization process: an initial phase involving high-temperature magmatic fluids, a main stage characterized by sulfidation and gold deposition, and a final stage marked by polymetallic overprinting. The Nam Xan deposit is therefore interpreted as the distal manifestation of a Permian arc-related magmatic system in which magmatic fluids migrated along structural conduits and precipitated gold through interaction with carbonate host rocks. The identification of these intrusions in the distal IRGS at Nam Xan informs regional exploration models in the Truong Son Fold Belt, demonstrating the potential of carbonate platforms near Permian intrusions for future mineral exploration. Full article

Radon (²²²Rn) is a noble, radioactive gas and tends to be accumulated in poorly ventilated enclosed spaces. Mainly due to its radioactive daughters and the α-particles emitted, ²²²Rn poses a risk of cancer and therefore its concentration in air and water should be kept under certain reference levels. Several methods have been developed to accurately measure ²²²Rn concentration in water, using α, β or γ counting. A well-established, but not the only, method involves γ-spectroscopy using a High-Purity Germanium (HPGe) detector to identify the ²²²Rn decay isotopes ²¹⁴Pb and ²¹⁴Bi, assuming they are in secular equilibrium with ²²²Rn. This technique requires costly, bulky equipment due to the HPGe’s operation at −196 °C and the need for substantial shielding. The present study introduces a more affordable and compact device, utilizing CdZnTe (CZT) crystals, which provide exceptional energy resolution in the 300 to 600 keV range, with nearly eight times the Full Width at Half Maximum (FWHM) of HPGe. Four stacked CZT detectors, each containing a 0.5 cm³ crystal, were compared with measurements from an HPGe detector. Water samples were collected from boreholes and taps in a region where radon concentration in water ranged from 10 to 900 Bq/L. The results are promising for samples around 100 Bq/L, considering the potential advancements of the device with larger CZT detectors. Additionally, the method has the potential for in situ use due to its handheld capability. Full article

As a result of long-term groundwater overexploitation, the thickness of the vadose zone in the NCP has significantly increased, leading to changes in moisture transport patterns and groundwater recharge processes. This research gathers data on soil water potential and moisture content by conducting in situ profile monitoring of a 30.4 m thick vadose zone. A 44.5 m geological borehole was drilled for the purpose of measuring the hydraulic parameters of undisturbed soil samples, collecting ³⁶Cl isotope tracer samples, and constructing a coupling model of the unsaturated–saturated zone with a depth of 47 m. The research objectives were to examine the moisture transport law and infiltration recharge mechanisms in deep vadose zones. Comprehensive analysis shows that the average infiltration velocity is 0.661–0.743 m/a and the average recharge intensity is 103.1–115.9 mm/a. The depth and silty clay play an important role in affecting the infiltration process. The characteristics of infiltration can be divided into three segments: rapid, slow, and stagnant. The residual pore gases in the clay strata have a certain inhibitory effect on moisture transport. The time required for precipitation infiltration is 75.14 years for a 44.5 m thick vadose zone; thereafter, new water replaces old water to continue recharging the aquifer. In recent years, the government has taken multiple actions to alleviate this continuous downward trend in groundwater levels, including river ecological flow replenishment and groundwater extraction reduction. Additionally, increased precipitation since 2021 has objectively halted the previous thickening trend of the vadose zone. It is recommended to further strengthen groundwater resource management and enhance groundwater-level monitoring and warning to prevent further declines. This research holds significant implications for the evaluation and sustainable management of groundwater resources in large-scale plains in semi-humid areas. Full article

This paper presents systematic petrological, whole-rock geochemical, and Sr-Nd-Pb isotopic studies on the mafic–ultramafic rocks of the Daaobaogou Ni-Cu sulfide deposit in the Dunhuang Block, Gansu Province. This study aims to reveal the nature of its source region, parent magma composition, and magma evolution processes. The results indicate that the parent magma of the ore-bearing intrusion in Daaobaogou originated from an enriched lithospheric mantle metasomatized by Paleozoic subduction processes. It exhibits high-magnesium characteristics and represents the product of a certain degree of evolution from a primitive magma. The magma evolution underwent significant fractional crystallization, with olivine beginning to crystallize at 1328 °C, following the crystallization sequence: olivine, clinopyroxene, plagioclase, and orthopyroxene. Sr-Nd-Pb isotopes and trace elements indicate that the magma experienced intense crustal contamination (approximately 10–20% upper crust) during its ascent. Full article

The Dajing giant Cu–Sn polymetallic deposit is located in the Cu–Sn–Ag–Pb–Zn polymetallic belt of the southern Great Xing’an Range, NE China. Research on its ore genesis is of great significance for understanding Sn polymetallic mineralization in this region. In this study, pyrite, arsenopyrite, and sphalerite were analyzed by electron-microprobe analysis (EMPA) and in situ S–Pb isotope analysis. Previously published fluid-inclusion microthermometric and H–O isotope data were also incorporated to constrain fluid evolution and ore genesis. Both in situ S and Pb isotopic compositions fall within short ranges. The δ³⁴S values suggest a sulfur reservoir with possible magmatic contribution, whereas Pb isotopes indicate a mainly crustal Pb signature in an orogenic setting. Arsenopyrite records variations in As, S, Fe, and Co contents from core to rim. The Co-rich core shows Co enrichment accompanied by Fe depletion, consistent with Co-for-Fe isomorphous substitution. These features indicate changes in local fluid chemistry during arsenopyrite growth. Sulfur isotope geothermometry based on coexisting late-stage pyrite–sphalerite pairs yields 118–233 °C, with an average of 159 ± 49 °C, indicating medium- to low-temperature hydrothermal activity during the late sulfide stage. The Dajing deposit is interpreted as a fault-controlled hydrothermal vein-type Cu–Sn polymetallic deposit formed in a Late Jurassic extensional setting. Ore precipitation was likely promoted by cooling during upward fluid migration away from the magmatic heat source, pressure release, meteoric-water mixing, and fluid–rock interaction with granitic rocks and Linxi Formation wall rocks. This study provides mineral-scale constraints on fluid evolution and ore genesis in the Great Xing’an metallogenic belt. Full article

Nitrogen oxides (NO_x), comprising nitric oxide (NO) and nitrogen dioxide (NO₂), are key precursors of atmospheric nitrate, a major component of fine particulate matter (PM_2.5) that critically affects air quality, human health, and ecosystems. Emission inventories provide detailed spatial and temporal information on NO_x sources, while stable isotope techniques offer an additional constraint for source apportionment. Here, we incorporated stable nitrogen isotopes (¹⁴N, ¹⁵N) into the widely used Multi-resolution Emission Inventory for China (MEIC) over South China, with a focus on the Pearl River Delta (PRD) region, one of the most highly urbanized and industrialized regions in China, using an isotopic mass–balance model. The 2008 MEIC inventory indicated that NO_x emissions across South China were spatially heterogeneous, dominated by transportation sources, and concentrated mainly in the PRD and other urban clusters. We then compared the simulated isotopic composition of emitted NO_x with atmospheric measurements to assess the role of emission sources in controlling atmospheric nitrate (NO₃⁻). The simulated δ¹⁵N(NO_x) values were found to generally underestimate the observed δ¹⁵N(NO₃⁻) values. This discrepancy highlights the need for future ¹⁵N-enabled air quality modeling to better represent both source contributions and atmospheric processing, thereby improving source apportionment, emission inventory evaluation, and our understanding of reactive nitrogen cycling. Full article

The Arkansas Alkaline Province (AAP) is made up of intrusive bodies throughout central Arkansas, one of which is a nepheline syenite body called Granite Mountain. The crystallization age and origin of nepheline syenites from Granite Mountain are still uncertain, in part due to the rarity of zircon grains in silica-undersaturated rocks, such as nepheline syenite. This study reports new zircon U-Pb ages and trace element contents from three nepheline syenite samples from Granite Mountain. The zircon U-Pb ages of these samples are 90.4 ± 0.6 Ma, reflecting the crystallization age for nepheline syenite from Granite Mountain. Zircon rare-earth element patterns display remarkable positive Eu anomalies, indicative of their mantle affinity. Whole-rock geochemical characteristics include depleted Nd–Hf isotopic compositions, high ²⁰⁶Pb/²⁰⁴Pb ratios (19.5), and positive Nb-Ta anomalies. Their Sr-Nd-Pb-Hf isotopic compositions and trace element ratios display characteristics of ocean island basalts (OIBs). The probable magmatic source of these samples is a mixture of enriched mantle 2 (EM2) and high ²³⁸U/²⁰⁴Pb (HIMU). Taken together, the geochemical data, in particular, the HIMU signature, suggest that the Granite Mountain nepheline syenites formed within a mantle plume (likely Bermuda) tectonic setting at 90.4 Ma, although a rifting origin cannot be ruled out. Full article

Tobacco cultivation leads to nicotine accumulation in soil, but how nicotine affects soil nitrification and ammonia-oxidizing microorganisms remains poorly understood. This study conducted a microcosm incubation using soil collected from a 10-year tobacco monoculture field. The soil was spiked with nicotine at 0, 10, or 100 mg kg⁻¹ (the two concentrations representing realistic root-zone levels and a worst-case residue hotspot, respectively) and incubated for 42 days under controlled conditions. Gross nitrification rates were measured by ¹⁵N isotope dilution, and the abundance (qPCR) and community composition (amplicon sequencing) of ammonia-oxidizing bacteria (AOB) and archaea (AOA) were determined at multiple time points. Results showed nicotine at 10 mg kg⁻¹ slightly stimulated nitrification, whereas 100 mg kg⁻¹ caused a transient inhibition (day 1) followed by a sustained stimulation, with gross nitrification rates increased by up to 2-fold compared to the control. Nicotine explained 22% of the variation in bacterial community composition and significantly enriched Intrasporangiaceae and Bryobacter while suppressing Bradyrhizobium. AOB-amoA copy numbers increased within 3 days of nicotine addition and correlated strongly with nitrification rates, whereas AOA-amoA responded only after 6 weeks. Phylogenetic analysis showed that Nitrosospira (cluster Np 39-19) dominated the AOB community. We conclude that nicotine exerts concentration-dependent, biphasic effects on soil nitrification and that AOB, not AOA, drive the nitrification response to nicotine in this agricultural soil. Our findings highlight the potential of nicotine to shape nitrogen cycling in tobacco-cultivated ecosystems and call for field validation under long-term residue conditions. Full article

The Mesozoic dykes in the Xingcheng area of western Liaoning Province in China were investigated through an integrated study involving zircon U–Pb geochronology, whole-rock geochemistry, and zircon Hf isotopic compositions to elucidate their emplacement phases, petrogenesis, and tectonic setting. The dykes are classified into two groups: felsic (granite porphyry, granite aplite) and mafic (diabase, lamprophyre). Emplacement occurred in four discrete phases: Late Triassic (229–212 Ma), Early Jurassic (ca. 179 Ma), Late Jurassic (162–152 Ma), and Early Cretaceous (133–102 Ma). The felsic dykes are characterized by high SiO₂ and alkali contents, low TFeO and MgO abundances, and belong to the high-K calc-alkaline I-type granite series. The mafic dykes exhibit low SiO₂, elevated MgO, and high Na₂O contents, displaying both alkaline and calc-alkaline affinities. Both dyke suites are consistently enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs), and depleted in heavy rare earth elements (HREEs) and high field-strength elements (HFSEs). Zircon ε_Hf(t) values for the felsic dykes range from −22.3 to −7.4, corresponding to two-stage model ages (T_DM2) of 2613–1729 Ma, indicating derivation from partial melting of Neoarchean to Paleoproterozoic crustal material. Late Jurassic mafic dykes yield ε_Hf(t) values between −27.8 and −20.2, consistent with an origin from partial melting of enriched lithospheric mantle. In contrast, Early Cretaceous mafic dykes display a bimodal ε_Hf(t) distribution (−12.9 to −9.5 and +4.3 to +8.4), suggesting a predominant enriched mantle source with variable inputs from depleted mantle components. Integrated with regional tectonic reconstructions, the data indicate that the Xingcheng area evolved within a post-collisional extensional regime following the amalgamation of the North China Craton and the Central Asian Orogenic Belt during the Late Triassic. The Jurassic magmatic pulses are attributed to an active continental margin setting associated with subduction of the Paleo-Pacific Plate, whereas the Early Cretaceous phase reflects regional extension triggered by rollback of the subducting Paleo-Pacific slab. Full article

The geographical origin fraud of tea is a serious challenge faced by the global tea market. This review systematically sorts out the full chain technical system from analysis and detection to data analysis in the field of tea origin traceability, reviews the traceability mechanism and application boundaries of four core technologies including stable isotopes, mineral element fingerprints, spectroscopy and mass spectrometry metabolomics, and emerging sensors, reveals the differential masking effect of the processing techniques of the six major tea types on chemical fingerprints, and systematically analyzes the methodological evolution of chemometrics and machine learning in origin discrimination. This article provides a systematic reference for understanding the overall pattern of the tea origin traceability technology system and the selection of differentiated traceability strategies for different tea types. Full article

The increasing frequency and intensity of hotter droughts are driving widespread forest dieback, yet the role of tree nutritional status in drought-induced growth dieback remains poorly understood. We investigated how nutrient composition across tissues (leaves, wood) relates to water use patterns and growth resilience in rear-edge populations of Scots pine (Pinus sylvestris L.) in Northeastern Spain. Using a multi-proxy approach, we combined analyses of foliar and sapwood nutrient concentrations, stable isotopes (δ¹³C, δ¹⁸O), and dendrochronological indicators across contrasting tree vigor classes. Defoliated trees exhibited pronounced shifts in elemental composition, including depletion of foliar K and increased concentrations of Ca, S, and Fe, alongside higher intrinsic water use efficiency and reduced growth resistance to drought. In contrast, the sapwood elemental composition was less responsive to defoliation but showed stronger associations with isotopic signals and drought resilience, suggesting its integrative role in tree functioning. Coordination of nutrient concentrations between tissues was limited, suggesting organ-specific regulation of nutrient allocation under drought stress. Our results reveal that nutrient imbalances are linked to water–carbon dynamics and drought responses and emphasize the importance of considering multi-organ nutrient dynamics to improve our understanding of long-term nutritional imbalances during drought-induced forest dieback. Full article

Integrated crop–livestock systems (ICLS) that couple crop production, cover crops, and grazing present a promising strategy for soil organic carbon (SOC) sequestration. Long-term assessments of SOC change under ICLS management are limited. This study quantified SOC stocks from management systems typical of the warm, humid southern Midwest, USA, including conventional continuous cereal crop production, permanent pasture, hardwood forest, and decadal-scale ICLS management. The ICLS consisted of no-till production of corn silage with a winter ryegrass cover crop grazed by cattle. We hypothesized greater SOC stocks in the ICLS relative to conventional management, with the greatest increase in surface horizons. Soil cores were collected to a depth of 120 cm, subset into 0–30 cm, 30–60 cm, and 60–120 cm sections, and analyzed for SOC, particulate, and mineral-associated organic matter. Results demonstrated that after 15 years, ICLS SOC stocks were significantly greater than conventionally managed fields and comparable to those of permanent pasture and hardwood forest. The SOC differences were predominantly in the upper 30 cm. Using a space-for-time approach, we calculated an average annual SOC accrual rate of 1.3 Mg C ha⁻¹ yr⁻¹, similar to estimated sequestration rates from biogeochemical model simulations. The majority of additional SOC was allocated to particulate organic matter. Significantly greater mineral-associated organic carbon was also observed. Stable carbon isotope data indicated the ryegrass cover crop was likely the primary source of additional SOC in the ICLS. These findings demonstrate the potential of ICLS to increase SOC and enhance soil health over decadal timescales. Full article

Marginal lacustrine systems are highly sensitive archives of hydrological fluctuations, climatic variability, and changes in sediment supply in continental basins. The Alagöz Formation (Late Miocene–Pliocene) exposed in the Haymana–Polatlı Basin, Central Anatolia, was investigated through integrated sedimentological, mineralogical, geochemical, and stable isotope analyses to constrain provenance, weathering history, and lacustrine hydrological variability. Facies analysis reveals a transition from alluvial–fluvial systems to a shallow marginal lacustrine environment subjected to short-term hydrological fluctuations. Mineralogical and geochemical data indicate that sedimentation occurred within a mixed carbonate–siliciclastic lacustrine system controlled by variable lake-water chemistry. Detrital mineral assemblages indicate contributions from metamorphic source rocks. Trace-element and REE signatures suggest derivation mainly from felsic-to-intermediate continental sources. Reworked carbonate fragments and fossil debris indicate recycling of older carbonate units. The occurrence of calcite, dolomite, and protodolomite reflects variable Mg/Ca ratios, whereas clay mineral assemblages record shifts between detrital input during relatively humid phases and chemically concentrated conditions. Palygorskite occurrence indicates localized and episodic alkaline conditions associated with short-lived evaporative concentration. Weathering indices (CIA, CIW, PIA, and ICV) suggest low-to-moderate chemical weathering and compositionally immature sediments, consistent with transitional humid to semi-arid climatic conditions. Trace-element systematics also indicate a minor mafic contribution to the detrital source. Stable isotope values (δ¹³C: −7.05‰ to +2.82‰; δ¹⁸O: −8.60‰ to −2.94‰ VPDB) and their weak correlation (r = 0.34) support a shallow, hydrologically dynamic lacustrine system dominated by freshwater input but episodically influenced by evaporative concentration. Taken together, the Alagöz Formation records a sensitive marginal lacustrine system shaped by short-term hydrological fluctuations. These findings provide a useful analog for understanding hydrologically sensitive marginal lacustrine systems developed in post-collisional continental basins under fluctuating semi-arid climatic conditions. Full article

The Shizui Cu–Pb–Zn deposit is located in central Jilin Province. It sits at the tectonic junction between the eastern Xing’an–Mongolia Orogenic Belt (XMOB) and the northeastern North China Craton (NCC). This is the first discovered Paleozoic Cu-polymetallic deposit in the region. Our study combines detailed geological investigation with systematic fluid inclusion analysis. We analyzed samples from four distinct paragenetic stages. Analytical methods include microthermometry, laser Raman spectroscopy, and hydrogen-oxygen isotope analysis. These data constrain the source, evolution, and precipitation mechanisms of the ore-forming fluids. The results delineate a clear evolutionary path: the ore-forming fluid originated as a high-temperature (346–437 °C), high-salinity (up to 51.68 wt.% NaCl equiv.) NaCl–H₂O–CO₂ system during the early quartz-sulfide stage (Stage I, Quartz ± Arsenopyrite ± Pyrite Stage), as evidenced by the coeval presence of high-salinity S-type and CO₂-rich C-type inclusions, indicating fluid immiscibility. The fluid then evolved into a boiling, medium temperature to high temperature (262–355 °C), high-salinity NaCl–H₂O system during the later part of early quartz-sulfide stage (Stage II, Quartz-Cu Polymetallic Sulfide Stage), a transition marked by the common coexistence of liquid-rich (L-type) and vapor-rich (V-type) inclusions with similar homogenization temperatures. This phase separation (boiling) served as the primary trigger for the massive deposition of chalcopyrite, arsenopyrite, and pyrite. Subsequently, the system cooled and diluted, transforming into a medium- to low-temperature (182–275 °C), low-salinity, partially homogeneous NaCl–H₂O system in the late quartz-sulfide stage (Stage III, Quartz-Pb-Zn Polymetallic Sulfide Stage). Finally, in the quartz-carbonate stage (Stage IV, Quartz-Carbonate Stage), the fluid temperature further decreased, resulting in a low-temperature (128–211 °C), low-salinity, homogeneous NaCl–H₂O system. Hydrogen-oxygen isotope data show that the calculated δ¹⁸O_H2O values decreased from +6.6‰ to +6.7‰ in Stage I to +3.4‰ to +3.9‰ in Stage II, and further to −0.4‰ in Stage III, while the δD values shifted from −91.6‰ to −90.6‰, to −94.4‰ to −94.2‰, and finally to −95.7‰. This trend indicates that the initial magmatic fluid progressively mixed with meteoric water. The geological characteristics, spatial association with Hercynian biotite monzogranite, developed skarn alteration, and the documented fluid evolution trajectory collectively affirm that the Shizui deposit is a typical skarn-type system. The deposit shares significant similarities in mineralization conditions, age, and tectonic setting with the skarn-type Tianbaoshan Pb–Zn–Cu–Mo deposits in the western segment of the XarMoron–Changchun Metallogenic Belt (XCMB). This correlation strongly suggests that the Paleozoic XCMB extends eastward and holds considerable potential for the discovery of late Paleozoic skarn-type Cu-polymetallic deposits in its eastern part. Full article