Species-specific isotopic analysis of mercury in marine biota: Systematic evaluation of extraction and oxidation methods for a straightforward analytical approach.

Follow the lead ! Tracing the lead sources of Notre-Dame de Paris over the centuries using chemical and isotopic analyses

Application of double spike multi-collector mass spectrometry to determination of iron isotopic composition in different iron phases in sea ice.

Analysis of barium isotopes, Ba/Ca, and Sr/Ca in extrapallial fluid elucidates factors controlling biomineralization of freshwater mussel shells

Density-dependent regulation of water use strategies in a desert plantation: stable isotope evidence from the Kubuqi Desert during the growing season.

Dredging alters sediment composition and hydrodynamics, disrupting organic matter distribution and deposit-feeder communities, yet its long-term effects on benthic food webs remain underexplored. We examined how dredging-induced sediment changes influence trophic niches of deposit feeders by analyzing abundance, resource use, and trophic structure of three deposit-feeding species and one predator in Gwangyang Bay, Korea, using stable isotope analysis. Sediment characteristics differed markedly between regions: the northern inner bay was dominated by fine, organic-rich sediments, whereas the dredged main channel contained coarser, organic-poor sediments associated with short water residence times. Despite these contrasts, sediment conditions alone did not explain deposit-feeder distributions; instead, recolonization capacity following disturbance appeared more important. Isotopic niche metrics (δ13C range, δ15N range, and corrected standard ellipse area) revealed substantial trophic niche overlap among deposit feeders (Capitella capitata, Magelona japonica, and Theora fragilis), with primary reliance on phytoplankton and microphytobenthos and minor contributions from riverine and marsh-derived organic matter. Although species-specific traits influenced feeding strategies, high phytoplankton availability likely promoted trophic convergence rather than niche partitioning. Pronounced niche overlap occurred in both dredged and non-dredged areas, indicating that resource availability, rather than sediment conditions, primarily structures benthic trophic interactions. Predatory polychaete, Scoletoma longifolia, occupied a higher trophic position but exhibited similar isotopic overlap across dredged and non-dredged areas, supporting trophic homogenization mediated by shared prey resources. Overall, our results demonstrate that in low-turbidity estuaries such as Gwangyang Bay, autochthonous microalgal availability-rather than dredging status-primarily governs benthic trophic dynamics, underscoring resource-driven controls on trophic structure following dredging.

Many species of aquatic organisms are currently overexploited and listed as vulnerable groups by the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Some of these aquatic species can now be produced by means of aquaculture methods and are traded as farmed products. Such products are not subject to fishing bans and under these scenarios, a delicate balance exists between the conservation of natural resources and the trade of farmed, albeit protected species. Traceability methods are becoming intrinsic components of protocols aimed to improve seafood supply chains. In addition to their role in natural resource management, traceability methods represent important tools in food innocuity issues given that they assist in guaranteeing food provenance and product inclusion into food safety processes. The implementation of effective traceability protocols reduces malpractices such as product mislabeling and illegal fishing. The latter encompasses social connotations for the legally established fishermen and farmers, who are better protected against the unfair competition exerted by illegally caught seafood. The dietary history of organisms affects the chemical characteristics of their tissues. These chemical characteristics can be measured by means of several analytical methods and used as reliable biomarkers to determine production method and geographical origin. The present review explores traditional, emerging, and combined analytical techniques that support the traceability processes of fish, mollusks, echinoderms, crustaceans and other groups of edible and ornamental aquatic organisms. An emphasis is placed on the application of stable isotopes analysis as a useful tool to distinguish farmed from wild aquatic organisms and to determine the provenance of seafood products.

Calibration of HD sensitivity factor for accurate trace hydrogen isotope analysis in Zr-2.5Nb alloy via spot heater-based thermal desorption mass spectrometry

The cat (Felis catus) is one of the worst invasive species, with well-documented impacts on biodiversity, especially on islands. Despite this, local administrations commonly implement trap-neuter-return (TNR) programmes to manage free-roaming cat populations. Here, we assess the effects of cat colonies on the endemic Tenerife lizard (Gallotia galloti). We used fruit-baited pitfall traps placed near and away from cat colonies to estimate lizard abundance and collect biometric data. Lizard abundance was lower near cat colonies compared with nearby control areas. Moreover, the individuals captured close to the colonies were smaller. Measurements of lizard carcasses found near colonies indicate that cats preferentially prey on larger individuals, explaining both their reduced abundance and their smaller body size. Interestingly, despite their smaller size, lizards near cat colonies presented higher scaled mass index values. Stable isotope analyses (δ13C and δ15N) of faecal samples suggest that these lizards partially rely on dried cat food available within colonies. Overall, cat colonies significantly altered lizard abundance, size structure and body condition. Given the ecological importance of G. galloti as both a seed disperser and prey, our findings highlight the need to limit the spread of free-roaming cat colonies, particularly in protected areas, to mitigate the effects on native biodiversity.

Compound-specific hydrogen isotope analysis of lignin methoxy groups for tea provenance discrimination: Comparison with dual-water equilibration.

• Enamel(oid) δ 66 Zn values are well preserved in Late Cretaceous marine vertebrates. • Zinc isotopes reveal significant resource partitioning among Cretaceous marine taxa. • Late Cretaceous sharks occupied top trophic positions comparable to today. Food web structures and trophic interactions among Late Cretaceous marine taxa remain largely ambiguous due to the challenges in reconstructing ecological interactions in the deep-time fossil record. Here we analyse enamel(oid) δ 66 Zn values, a trophic-level proxy, across 16 marine vertebrate taxa from two Turonian–Coniacian boundary localities in New Mexico and Kansas, USA, deposited in what was then the Western Interior Seaway (WIS). Our results demonstrate well-preserved enamel(oid) δ 66 Zn values in both localities, but locality-specific differences in the diagenetic modification of dentine δ 66 Zn values. We highlight significant resource partitioning among the analysed taxa within the WIS, including sharks. For example, Archaeolamna , Cretodus and Cretoxyrhina occupied very high trophic positions, whereas Cretalamna was likely foraging opportunistically across several trophic levels. Our study expands the use of enamel(oid) δ 66 Zn analysis to Mesozoic fossils for the first time and demonstrates that robust reconstructions of food web dynamics and trophic interactions are possible in deep time as far back as 90 million years ago, providing new avenues for palaeobiological and evolutionary research.

This study provides an integrated isotopic characterization and interpretation of carbonate phases in the Barra Velha Formation (BVF) of the Santos Basin, a key interval within the Brazilian pre-salt reservoirs. By combining petrography, stable and radiogenic isotope analyses (δ 13 C, δ 18 O, 87 Sr/ 86 Sr), we investigated carbonates from seven wells across three oil fields. The data reveal that various calcite and dolomite phases in the BVF exhibit carbon isotopic compositions (δ 13 C V-PDB) between -1.15‰ and +4.65‰, supporting an abiotic origin for carbonate precipitation, likely driven by CO 2 degassing in a hyper-alkaline lacustrine environment, intrinsically associated to rift-related processes associated with the opening of the South Atlantic. Strontium isotope ratios ( 87 Sr/ 86 Sr) ranging from 0.711 to 0.714 suggest significant crustal input, without marine contribution. The isotopic compositions are consistent across carbonate phases and oilfields, indicating stable geochemical conditions in the South Atlantic pre-salt lacustrine system. These findings reinforce the interpretation of predominantly abiotic carbonate precipitation, ruling out a dominant microbial control, and support deposition within a large, hydrologically interconnected lacustrine system, providing critical constraints for reservoir characterization and exploration models in the Brazilian offshore pre-salt province. • Isotopic data reveal homogeneous δ 13 C–δ 18 O– 87 Sr/ 86 Sr across Santos Basin wells. • Radiogenic 87 Sr/ 86 Sr (∼0.713) denotes crustal–hydrothermal sourcing, no marine input. • Calcite and dolomite precipitated under stable alkaline lacustrine–rift settings. • Isotopic uniformity indicates a hydrologically connected pre-salt lake system. • Evidence supports abiotic carbonate formation in Aptian pre-salt lacustrine systems.

Despite the advantages of laser absorption spectroscopy for high-sensitivity and continuous isotope measurements, isotope analyzers often suffer from concentration dependence and nonlinear errors, particularly over wide concentration ranges and at low signal-to-noise ratios, which severely limit measurement accuracy. Here, we developed a dual-gas carbon isotope analyzer for methane (CH4) and carbon dioxide (CO2) based on off-axis integrated cavity output spectroscopy (OA-ICOS) and proposed a feature-enhanced weighted feedforward neural network (FNN) for correcting concentration-dependent effects. By constructing a 9-dimensional feature space containing high-order interaction terms and combining boundary-constrained data augmentation with a region-of-interest weighting strategy, nonlinear instrument responses were effectively decoupled from true isotope values. After correction, concentration dependence was eliminated across the measurement range, with residual errors within ±0.4‰. Excellent agreement with reference values was achieved across different isotopic compositions (R2 > 0.999). Long-term stability tests indicated that at 2 ppm of CH4 and 500 ppm of CO2, the δ13C measurement precision (1σ) reached 0.19‰ and 0.075‰, respectively, with a 5 min integration time. Furthermore, a continuous field comparison with a commercial analyzer showed high consistency in capturing dynamic atmospheric isotope variations. These results demonstrate that neural network-based correction provides an effective solution for mitigating concentration dependence in high-precision laser isotope spectroscopy.

Iron (Fe) isotopes act as a powerful tracer in geological processes for analyzing terrestrial and extraterrestrial materials. Laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) is widely used for in situ Fe isotope analysis. However, its application is limited by argon (Ar)-based polyatomic isobaric interference and reduced sensitivity under high mass resolution, restricting investigations of intragrain variability and fine-grained extraterrestrial samples. Herein, the first femtosecond LA collision/reaction cell (CRC) MC-ICP-MS analysis for high spatial resolution of Fe isotope is reported. A hydrogen (H2)-helium (He) gas mixture in the CRC effectively suppressed Ar-based interferences, enabling accurate analysis of Fe isotopes in a low-resolution mode. Substitution of the conventional ultraviolet laser with a 1028 nm infrared laser significantly enhanced ablation rates, without compromising the stability of Fe isotope ratios. Optimization of the analytical conditions increased Fe isotope sensitivity by >50-fold than conventional LA-MC-ICP-MS, providing a strong foundation for high spatial resolution analysis. Replicated analyses were performed on six Fe-bearing materials (magnetite, ilmenite, pyrite, chalcopyrite, olivine and basalt glass) using the as-developed method with small beam spots of 8-15 μm in a single-spot mode. The measured δ56FeIRMM-014 values are consistent with reference values, with an external reproducibility of 0.09‰-0.15‰ (2SD). Compared with traditional Fe isotope microanalysis techniques, the proposed method improves spatial resolution of the analytical area by 1-2 orders of magnitude. The method was further applied to impact glass, ilmenite, and olivine samples collected by China's Chang'e-6 lunar missions, revealing significant intraparticle Fe isotope variability at micrometer scales, indicating the capability of LA-CRC-MC-ICP-MS to resolve Fe isotope heterogeneity in fine-grained samples with complex compositions. Thus, our method highlights its potential for high spatial resolution of isotopes in planetary samples.

The standard addition method (SAM) determines sample isotope compositions from mixtures of samples and standards with known isotope ratios, which has been widely applicated for low-mass or low-concentration samples. However, conventional off-line SAM is labor-intensive and can suffer from substantial uncertainty (≥2.5%) in the sample proportion (f value) within the mixture, which compromises isotopic accuracy. Here we present a novel online SAM specifically designed to address these challenges. The reference gas routinely used in conventional analyses is innovatively repurposed as a standard and introduced online directly into the sample stream via the ConFlo IV interface. The isotope ratios of samples are subsequently calculated using an isotope mass balance model. The method is evaluated and validated by measuring the sulfur (S) isotope compositions of standard materials and natural samples using elemental analyzer isotope ratio mass spectrometry (EA-IRMS). The uncertainty in the f value is less than 0.148%, ensuring the accuracy of calculated results. The approach eliminates the need for manual standard addition, significantly enhancing measurement efficiency. The method achieves accuracy and reproducibility comparable to conventional techniques while reducing the sample mass by 75%. Based on the developed approach, coarse to ultrafine atmospheric particulate matter was successfully measured in a haze event, revealing size-dependent S isotope variations. Importantly, this methodology is highly practical and easy to be widely adopted for current standard equipped EA-IRMS laboratories, as it requires no additional labor and financial investments for hardware upgrading proposed in previous publications.

Abstract Determining long‐term soil erosion and deposition rates and understanding landform evolution are important for managing both natural and human‐modified landscapes, including postmining rehabilitation sites. Although various landform evolution models (LEMs) have been developed to simulate erosion processes and landscape change, relatively few studies have directly compared modelled outputs with field‐based erosion estimates. This study evaluates and compares two LEMs, (i) SIBERIA, which is widely used in the Australian mining sector, and (ii) SSSPAM, a newer coupled soilscape–LEM, together with the well‐established soil erosion model (the revised universal soil loss equation). A formerly grazed hillslope in the Upper Hunter region of New South Wales was used as the case study, and a high‐resolution light detection and ranging (LiDAR)‐derived digital elevation model was used as the landscape input. Field‐based erosion rates were quantified using sediment yield data from a catchment dam and 137 Cs isotopic analysis. Sediment trap measurements indicated erosion rates ranging from 0.43 to 0.61 t/ha/year, while 137 Cs results showed erosion and deposition rates of up to 1.5 and 1.1 t/ha/year, respectively. SIBERIA predicted erosion rates of 1.07 t/ha/year under dense vegetation cover and 3.74 t/ha/year under moderate cover, while SSSPAM estimated 0.35 and 2.43 t/ha/year for the same conditions. The RUSLE model predicted an average erosion rate of 2.23 t/ha/year, with values ranging from 0.58 to 4.65 t/ha/year. Overall, the modelled erosion estimates were broadly consistent with the field observations, demonstrating the ability of both SIBERIA and SSSPAM to reproduce realistic hillslope erosion rates. These findings support the use of LEMs as valuable tools for guiding sustainable land management and rehabilitation practices in both natural and constructed landscapes.

Due to its neurotoxicity and tendency to bioaccumulate, mercury (Hg) is a risk to both human and environmental health. Most Hg studies focus on aquatic systems due to their longer food chains and predatory fish. Yet opportunistic terrestrial predators such as wolves (Canis lupus) are less studied despite the potential for high-Hg prey in their diets that could lead to high concentrations and subsequent health effects. Here, we studied the movement of Hg to wolves from their prey across two regions of the Northwest Territories (NWT), Canada between 2006 and 2024 by combining stomach content data with stable isotope analysis of over 350 individuals. While terrestrial prey such as caribou dominated the diet of wolves in both regions (>55% of stomachs), a small number of wolves in both regions recently consumed aquatic prey (5%) and these aquatic prey had significantly higher Hg concentrations than terrestrial prey (P < 0.001). This led to higher Hg concentrations in wolves that had eaten aquatic prey relative to those eating semi-aquatic and terrestrial prey, and is likely responsible for Hg trophic magnification factors (TMFs) that matched or exceeded those typically observed in aquatic systems. These findings highlight the transfer of Hg from aquatic to terrestrial food webs and the potential for health risks to terrestrial predators. Mercury concentrations in wolves remained well below expected animal health effect thresholds and there was no evidence for an increase in concentrations in either region over the last decade, but the high concentrations in some prey species and trophic magnification in wolves illustrate the vulnerability of terrestrial predators to Hg exposure when their diets contain aquatic prey.

Isotope ratio (IR) determinations on individual particles can provide valuable information relative to the sample, including processing and dating, which could be valuable to geological and nuclear material analysis communities. In comparison to "bulk" measurements, in which all particle information is lost and homogenized within a sample, "particle" measurements allow for fingerprinting and can provide unique insights related to the sample's nano- and micro- compositions. Furthermore, the complex nature of particles, with potential isobaric interferences from either the matrix or other elements within the same particle, poses a significant analytical challenge for conventional mass spectrometry platforms employed for elemental analysis due to their limited mass resolution. Presented here is the first demonstration of an ultrahigh resolution method for single particle (SP) isotopic analysis using the liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma ionization source coupled to an Orbitrap mass spectrometer and FTMS Booster X2T acquisition/processing system. For proof of concept, well-characterized CeO2 microparticles with a nominal diameter of 1.0 μm were analyzed at a mass resolution of ∼330,000. Important instrumental parameters were optimized to enable the detection of single particles. The 142Ce/140Ce ratio of individual particles and the population average were determined and compared to an SP inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS) analysis. The isotopic accuracy and precision were determined by two methods and found to be in good agreement with the SP-ICP-TOF-MS method, with the linear regression slope method providing a more accurate ratio, showing a ∼1.4% relative difference from the ratio determined from a particle digest. The encouraging performance of the method was further supported by a determined detection limit of 2.9 fg (142Ce). The developed method is anticipated to overcome many of the challenges posed by isobaric interferences encountered in conventional mass spectrometry techniques when analyzing real-world samples for particle isotopic composition.

Presuming pathways of sea turtles using stable isotopes from shells of epibiont barnacles.

The stable carbon isotope (δ13CDOC) of dissolved organic carbon (DOC) is one of the most informative tracers for marine carbon cycling studies. Yet its determination is critically constrained by reliance on isotope ratio mass spectrometry (IRMS). Conventional IRMS-based methods require large sample volumes and labor-intensive pretreatment but offer low measurement throughput, significantly limiting their application in field research and high spatiotemporal resolution studies. To resolve these issues, we developed a field-deployable δ13CDOC analysis method and established an IRMS-independent device by coupling a self-developed ultrahigh-sensitivity mid-infrared tunable diode laser absorption spectroscopy (MIR-TDLAS) isotope spectrometer with a high-temperature catalytic oxidation (HTC) module, enabling a continuous "injection-oxidation-analysis" workflow on a single platform. Integrated with hardware enhancements and a physical-model-based spectral processing algorithm, the device achieved an approximately 100-fold improvement in sensitivity for both 12CO2 and 13CO2, yielding detection limits of 3.98 ppbv and 70 pptv, respectively. This performance enabled quantification of isotope signals from ppmv-level CO2 without any CO2 trapping or enrichment. Only 300 μL of seawater was required to determine δ13CDOC within approximately 6 min, providing a δ13C precision of ∼1.0‰. A measurement deviation of less than 0.336‰ was achieved using an empirical correction model developed to correct concentration-dependent isotopic bias. By demonstrating its rapidness, precision, and portability, this laser absorption spectroscopy-based method establishes a novel approach for high-throughput and field-deployable DOC carbon isotope analysis.