Chemical Geology最新文献

{"title":"Cu isotopes resolve acid mine drainage sources and treatment pathways at the argo tunnel water treatment plant","authors":"Molly C. Morgan ,&nbsp;Ryan Mathur ,&nbsp;Elizabeth A. Holley ,&nbsp;Cameron Lasinsky","doi":"10.1016/j.chemgeo.2026.123250","DOIUrl":"10.1016/j.chemgeo.2026.123250","url":null,"abstract":"<div><div>AMD poses severe environmental hazards, releasing toxic metals into ecosystems and adversely impacting water quality. This study leverages Cu isotopes as environmental tracers to identify AMD sources and decode treatment mechanisms at the Argo Tunnel Water Treatment Plant (ATWTP) in Idaho Springs, Colorado. The δ⁶⁵Cu isotopic signatures from distinct sources (Argo Tunnel, Virginia Canyon, and Big Five Tunnel) effectively differentiate the Cu contributions from each source. Mass balance modeling reveals that Mn-oxides accounted for 54% of Cu retention, and Mn-oxide adsorption is the dominant mechanism for Cu removal at the ATWTP, although Fe-oxides are more abundant. These findings suggest that adjusting Mn concentrations in influent waters could enhance Cu removal, forming the basis of the proposed CLEAR PATH strategy (Chemical Lime Enhancements for Advanced Remediation and Purification At Treatment Hubs) to optimize AMD treatment. This research also demonstrates the utility of Cu isotopes for tracing AMD sources and refining treatment processes, offering actionable insights for improving environmental remediation in mining- impacted regions. This work provides the first plant-wide copper-isotope mass balance ever reported for a full-scale AMD treatment plant and the first operational quantification of Cu partitioning between co-precipitating Fe- and Mn-oxides.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123250"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal and inter-estuarine Sr cycling controlled by water mixing and hydrogenous sediments: Low 87Sr/86Sr in groundwater loss via the Gulf of Cambay","authors":"Abul Qasim ,&nbsp;Satinder Pal Singh","doi":"10.1016/j.chemgeo.2025.123231","DOIUrl":"10.1016/j.chemgeo.2025.123231","url":null,"abstract":"<div><div>Radiogenic Sr isotopes are widely used to quantify the coastal water balance and to determine the terrestrial Sr contributions to the oceans. Here, we present the novel seasonal distributions of dissolved Sr concentration and ⁸⁷Sr/⁸⁶Sr in the Gulf of Cambay estuarine waters (surface and subsurface samples, <em>n</em> = 189) collected during 2016–2017. The primary objective is to elucidate the seasonal and anthropogenic forcings of dissolved Sr cycling in the modernized Narmada and Tapi estuaries, specifically to quantify the less radiogenic Sr contribution from terrestrial groundwater discharge (TGD), which leaches extensive continental flood basalt (Deccan Trap) and ancient limestone deposits in the hinterland. The seasonal scatter plots of salinity versus dissolved Sr exhibit significant and strong correlations (r² ≥ 0.99; <em>p</em>-value &lt;0.0001) in the estuarine surface waters. However, the seasonal mixing of modern seawater and river waters fails to explain the reproducible and systematic variations in dissolved Sr concentration and ⁸⁷Sr/⁸⁶Sr, particularly during non-monsoon seasons. The estuarine Sr isotope budget reveals the vital roles of TGD and hydrogenous sediments, along with a possibility of minor anthropogenic input. The internally recycled Sr, most likely from hydrogenous sediments, reflects the riverine isotopic signature in the Narmada estuary during the monsoon and post-monsoon seasons, while it reflects the seawater signature in the Tapi estuary, irrespective of the seasons. In the Narmada estuary, the TGD fluxes of ∼2.1–3.8 × 10⁷ m³/d, 2.7 × 10⁶ m³/d, and ∼ 5.8 × 10⁵ m³/d are calculated for the monsoon, post-monsoon, and pre-monsoon seasons, respectively. The TGD contribution is not essentially required in the water-stressed Tapi estuary. The collective riverine and TGD flux-weighted Sr supplies of ∼1.9–2.3 × 10⁸ mol/y (⁸⁷Sr/⁸⁶Sr ∼ 0.70959–0.70964) and ∼ 5.2–8.5 × 10⁷ mol/y (⁸⁷Sr/⁸⁶Sr ∼ 0.70878–0.70885) from the isotopically heterogeneous Narmada and Tapi estuaries, respectively, ultimately go to the Arabian Sea. Assuming an order of magnitude higher recycled seawater component as compared to TGD and the average Sr composition of vicinal groundwater, both estuaries together have the potential to contribute a massive supply of less radiogenic Sr ∼1.3–1.8 × 10⁹ mol/y (⁸⁷Sr/⁸⁶Sr ∼ 0.70891–0.70895), which is equivalent to ∼0.3–0.5 % of the global marine radiogenic Sr isotope budget.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123231"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145893635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biomineralization induced by Shigella dysenteriae JS3: The mechanism, and the differences between biotic and abiotic whewellite and struvite","authors":"Na Guo ,&nbsp;Jizheng Qiao ,&nbsp;Shuhua Zhang ,&nbsp;Shengzhe Gao ,&nbsp;Yanhong Zhao ,&nbsp;Chao Han ,&nbsp;Hui Zhao ,&nbsp;Yanyang Zhao ,&nbsp;Xiao Gao ,&nbsp;Ruirui Meng ,&nbsp;Bin Cao ,&nbsp;Yu Li ,&nbsp;Hao Dong ,&nbsp;Jie Li ,&nbsp;Maurice E. Tucker ,&nbsp;Huaxiao Yan ,&nbsp;Zuozhen Han","doi":"10.1016/j.chemgeo.2025.123221","DOIUrl":"10.1016/j.chemgeo.2025.123221","url":null,"abstract":"<div><div>Whewellite and struvite have been successfully biomineralized; however, the underlying mechanisms and the distinctions between the biotic and abiotic minerals remain scarcely documented. Here, <em>Shigella dysenteriae</em> was used to induce whewellite and struvite precipitation. Concurrently, the biomineralization mechanism and the distinguishing characteristics of the biominerals, which set them apart from abiotic minerals, were investigated. JS3 bacteria are capable of producing alkaline phosphatase and ammonia, thereby generating an alkaline environment (pH 8.7). Under the influence of calcium (Ca²⁺), magnesium (Mg²⁺), and oxalate (C₂O₄²⁻) ions, the contents of aromatic protein-like, tryptophan-like, fulvic acid-like, and humic acid-like substances within bacterial extracellular polymeric substances increased. Ca²⁺ facilitated the precipitation of Mg²⁺, whereas C₂O₄²⁻ exhibited an antagonistic effect. Whewellite and struvite exhibited preferentially oriented growth. The biotic forms of whewellite displayed significantly more negative δ¹³C values (−15.7 ‰ to −22.9 ‰) and δ¹⁸O values (−15.0 ‰ to −7.2 ‰) compared to their abiotic counterparts, which showed δ¹³C and δ¹⁸O values of −11.1 ‰ and − 4.8 ‰, respectively. Similarly, biotic struvite demonstrated more negative δ¹⁸O values (−7.3 ‰ to −8.5 ‰) than abiotic struvite (−4.4 ‰). Biominerals tend to display a high degree of habit diversity and contain more complex functional groups derived from organic components such as lipids, proteins, and hydrocarbons. C–N–C, C–NH₂, N–C=O, C–O–PO₃, P<img>O, C–PO₃, and S<img>S can serve as potential indicators for distinguishing biogenic minerals. This study helps to further understand the biomineralization mechanisms underlying the formation of human urinary tract stones and to distinguish between biotic and abiotic minerals in nature.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123221"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145823502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photochemistry of Fe (II) and carbonate-bearing waters and the influence on Greenhouse Gas production in Early Mars","authors":"V.B. Rivera Banuchi ,&nbsp;J. Gong ,&nbsp;E.N. Mansbach ,&nbsp;T. Bosak ,&nbsp;J.A. Hurowitz","doi":"10.1016/j.chemgeo.2025.123210","DOIUrl":"10.1016/j.chemgeo.2025.123210","url":null,"abstract":"<div><div>Aqueous iron UV photooxidation, a proposed pathway for early Martian iron deposits produced in surface environments, produces hydrogen gas, a potentially important greenhouse gas for early Mars. This experimental study focused on iron photooxidation in the presence of dissolved inorganic carbon (DIC) at a range of concentrations that represent partial pressures of CO₂ (0.1–1 bar), consistent with estimated atmospheric pressures and compositions on early Mars. We report in-situ sampling of gas headspace to understand the extent to which DIC impacts the production of hydrogen gas that may be produced from aqueous iron photooxidation. The experiments demonstrate that ferrous iron photooxidation does not occur at any of the tested DIC concentrations (3.4–35 mM). Ferrous iron carbonate minerals were precipitated at pH conditions above 6, while maintaining relatively high dissolved iron concentrations at siderite saturation. We observed hydrogen and methane gas production at varying initial conditions, but no clear relationships to either iron loss to oxidation and/or precipitation or DIC concentrations could be inferred. Instead, we suggest that hydrogen is a byproduct of methane photolysis. The methane itself was sourced from an unknown background organic carbon compound from residual organic impurities in the deionized water source utilized in the experiments and is unrelated to iron photochemistry. These observations indicate that iron photooxidation is an unlikely mechanism to have produced hydrogen and precipitated iron oxide minerals at near-neutral pH in the presence of 0.1–1 bar CO₂ on early Mars.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123210"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Confinement properties of zeolite-rich rocks with respect to water and various ionic tracers","authors":"Flora Parrotin ,&nbsp;Emmanuel Tertre ,&nbsp;Sophie Billon ,&nbsp;Dimitri Prêt ,&nbsp;Serge Lefevre ,&nbsp;Rémi Guichard ,&nbsp;Baptiste Dazas ,&nbsp;Michaël Descostes ,&nbsp;Sébastien Savoye","doi":"10.1016/j.chemgeo.2025.123203","DOIUrl":"10.1016/j.chemgeo.2025.123203","url":null,"abstract":"<div><div>The studied materials are zeolite-rich rocks (&gt;70 wt% analcime, named analcimolite) forming a laterally continuous aquitard within the southern of the Tim Mersoï Basin (Niger). This unit, commonly referred to as the Abinky Formation, occurs as three mineralogical facies: a reduced facies containing Fe-chlorite, an oxidized facies with hematite, and an intermediate ‘transition’ facies. This analcimolite unit acts as an aquitard, separating the overlying and underlying sandstone aquifers, the latter locally providing potable water. Due to the low permeability of these analcime-rich rocks, diffusion is expected to be the dominant transport mechanism. However, no data on transport properties in zeolite-rich formations have been reported, and the mobility of water and ionic solutes remains unknown. This study aims to characterize diffusion in the three facies of the Abinky formation, identifying key controls on water and ion transport prior to any anthropogenic perturbation.</div><div>Through-diffusion experiments using water tracers (HDO and HTO) showed that water diffusion (effective diffusion coefficient from 1.3 to 2 × 10⁻¹¹ m²/s) is primarily controlled by pore throat size rather than total porosity. A dual-porosity model was required, distinguishing a fast-transport network (open, low-tortuous zones) from a slow one (confined, tortuous zones). Despite variations in diffusion coefficients, all data are interpreted with capacity factors equal to total external porosity measured by water impregnation (excluding crystal water located in zeolite micropores). This confirms that water behaves as an inert tracer and that micropores contribute negligibly to water migration. For ionic tracers in reduced facies, ³⁶Cl⁻ is partially excluded from external pores (anionic exclusion) and slightly adsorbed, with an extent of about 0.1 meq/100 g, a very small value compared to the cation exchange capacities of such rocks (up to ∼40 meq/100 g for H⁺ and NH₄⁺). In contrast, ²²Na⁺ exhibits strong adsorption due to isotopic exchange with ²³Na⁺ in the analcime framework, leading to a diffusivity ∼4 times higher than that of water. This dataset is a first step in constraining reactive transport models of water and solutes in zeolite-rich porous media under environmental conditions and prior to anthropogenic disturbance.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123203"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calcite TLM as a new natural reference material for in situ U-Pb geochronology and its geological implications","authors":"Tianyi Li ,&nbsp;Ranran Chen ,&nbsp;Shitou Wu ,&nbsp;Rolf L. Romer ,&nbsp;Nick M.W. Roberts ,&nbsp;Kerstin Drost ,&nbsp;David Chew ,&nbsp;Marcel Guillong ,&nbsp;Qian Ma ,&nbsp;Yahui Yue ,&nbsp;Shuangjian Li ,&nbsp;Bohang Xie ,&nbsp;Ahmatjan Abdurahman ,&nbsp;Hao Wang ,&nbsp;Huixi Lin ,&nbsp;Yueheng Yang ,&nbsp;Xusheng Guo","doi":"10.1016/j.chemgeo.2025.123230","DOIUrl":"10.1016/j.chemgeo.2025.123230","url":null,"abstract":"<div><div>Calcite (CaCO₃) forms in a wide variety of geological environments as both a primary and secondary mineral phase and may contain sufficient U for U-Pb geochronology. The limited availability of well-characterized calcite reference materials, however, has impeded its broader application in microanalysis. In this study, a natural calcite sample (TLM) was characterized and assessed as a potential primary reference material for in situ U-Pb geochronology. U-Pb isotopic analyses were conducted across nine independent laboratories using laser ablation (Q, SF, MC)-ICP-MS and isotope dilution (ID)-TIMS, to examine the homogeneity and to determine the U-Pb age of TLM. Calcite TLM has an age homogeneity at the level of ∼ 1.0 %, as indicated by multiple analyses from different laboratories. ID-TIMS analysis of 14 aliquots yielded an intercept age of 222.5 ± 2.8 Ma (2 s) with an initial ²⁰⁷Pb/²⁰⁶Pb value of 0.8380 ± 0.0013. Calcite TLM has an age uncertainty of 1.28 %, which is considerably lower than that of WC-1 (∼2.5 %). Calcite TLM has U and Pb contents of ∼0.35 μg g⁻¹ and ∼ 0.02 μg g⁻¹. Additional C and O stable isotope, radiogenic Sr isotope and trace element compositional data indicate that calcite TLM is likely sourced from meteoric water and indicate that the recurrent karstification may have affected the studied area as late as the Triassic.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123230"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145895534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The intermediate solid solution (ISS) of the Cu-Fe-S system: Phase equilibria calculation at elevated temperatures based on Gibbs energy modeling","authors":"Peter Waldner","doi":"10.1016/j.chemgeo.2026.123245","DOIUrl":"10.1016/j.chemgeo.2026.123245","url":null,"abstract":"<div><div>The phase equilibria of the Cu-Fe-S system are calculated from liquidus to medium temperatures based on Gibbs energy modeling of the intermediate solid solution (ISS). The compound energy formalism is used for a suitable thermodynamic model to account for the pronounced solid solution character of ISS. The obtained Gibbs energy as a function of composition and temperature allows the computation of complex phase relations with high-temperature modifications of bornite and pyrrhotite, pyrite and chalcopyrite, of which a Gibbs energy expression as a function of temperature is also provided. For the first time, a direct comparison is made public between the well-known experimental isoplethal phase diagram along the CuFe–S join, which was provided more than fifty years ago by <span><span>Barton (1973)</span></span>, and a thermodynamically computed phase diagram section. A detailed comparison with experimental phase equilibria data on the homogeneity range of ISS at 800 °C, 760 °C, 700 °C and 600 °C with calculated results is carried out. In total three isoplethal and four isothermal sections of the Cu-Fe-S phase diagram are computed, and the agreement with experimental data available in the literature ranges from fair to very satisfactory.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123245"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145902349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical systematics of spreading ridge-arc collision – Philippine Sea CBF rift and the Izu-Bonin arc","authors":"Osamu Ishizuka ,&nbsp;Rex N. Taylor ,&nbsp;Taichi Sato ,&nbsp;Gen Shimoda ,&nbsp;Yumiko Harigane ,&nbsp;Susumu Umino ,&nbsp;Izumi Sakamoto ,&nbsp;Yuka Yokoyama ,&nbsp;Koki Mori ,&nbsp;Kenichiro Tani ,&nbsp;Yasuhiko Ohara ,&nbsp;Chris E. Conway","doi":"10.1016/j.chemgeo.2026.123232","DOIUrl":"10.1016/j.chemgeo.2026.123232","url":null,"abstract":"<div><div>Triple junctions between fundamental tectonic units are where different compositions and magmatic processes interact. We investigated the intersection of a spreading center with an island arc within the Philippine Sea Plate, i.e. an arc-ridge-arc triple junction, using a combination of submersible sampling and shipboard geophysics. We use Ar<img>Ar dating, elemental concentrations and Sr-Nd-Pb radiogenic isotope ratios to constrain the structure, age and origin of magmatism as spreading interacted with the arc.</div><div>Between 33 and 31 Ma the tip of the West Philippine Basin spreading center was in the back-arc west of the Kyushu-Palau arc. Spreading volcanism had mantle-like Ce/Pb and Th/Ce indicating a lack of slab flux. Radiogenic isotopes form a trajectory towards low ¹⁴³Nd/¹⁴⁴Nd and high ^20xPb/²⁰⁴Pb, but extend to Δ²⁰⁸Pb/²⁰⁴Pb &gt; 85 which corresponds to an EM-2-like mantle component rather than pelagic sediment input from the slab.</div><div>The final stage of spreading-related activity occurred between 31 and 28.5 Ma when the spreading axis rotated from NW-SE to <em>E</em>-W and propagated eastwards into the arc. It resulted in magmatism contemporaneous with the adjacent frontal arc. This final magmatism extended the radiogenic isotopic trajectories observed in the earlier spreading towards less radiogenic Pb and higher ¹⁴³Nd/¹⁴⁴Nd, i.e. towards MORB from the EM-2 component. However, during the final stage magmatism La/Sm, Nb/Zr increased while Pb and Sr isotopes became progressively more radiogenic, demonstrating a progressive decrease in the degree of partial melting and preferential tapping of the EM-2 component. This change in melt generation and composition appears a common process at the end of spreading.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123232"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145902350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A multi-isotope deconvolution approach to correct for hydride and xenon interferences during double spike barium isotope analyses with MC-ICP-MS","authors":"Qasid Ahmad ,&nbsp;Hongjie Zhang ,&nbsp;Sune G. Nielsen","doi":"10.1016/j.chemgeo.2025.123209","DOIUrl":"10.1016/j.chemgeo.2025.123209","url":null,"abstract":"<div><div>Precise and accurate stable barium isotope (δ^138/134Ba relative to the NIST3104a standard) measurements are crucial for geochemical studies, as natural variations can be small. Double spike Ba isotope analysis by MC-ICP-MS is typically the preferred method for generating reliable Ba isotope data as it effectively corrects for instrumental mass fractionation and isotope fractionation during chemical separation, while also providing precise concentrations via isotope dilution. However, measurement of 50 ng or less of Ba using high sensitivity interface cones can be challenging due to the effects of isobaric interferences from trace Xe in the Ar plasma. Here we demonstrate that interferences from Ba-hydrides (BaH⁺) also have significant effects on double spike corrected δ^138/134Ba-values and, therefore, must be assessed and corrected.</div><div>We present a multi-isotope deconvolution strategy utilizing a ¹³⁵Ba–¹³⁶Ba double spike and three independent inversions using different un-spiked isotope pairs (¹³⁴Ba–¹³⁷Ba, ¹³⁴Ba–¹³⁸Ba, and ¹³⁷Ba–¹³⁸Ba) to solve the double spike equation. Each inversion independently calculates δ^138/134Ba that is differently affected by both background Xe and hydride interferences during the measurement. We show that the Xe correction is smallest for the ¹³⁷Ba–¹³⁸Ba inversion, which allows accurate Ba isotope data to be obtained for this inversion even when &lt;5 ng of Ba is consumed during triplicate sample measurements. However, the ¹³⁷Ba–¹³⁸Ba inversion also carries the largest effect from hydride formation, which we correct for using a combined ¹³⁴Ba–¹³⁸Ba/¹³⁷Ba–¹³⁸Ba inversion method. This approach produces long-term external reproducibility for rock reference materials of ±0.025 ‰ (2SD) when consuming less than 50 ng of Ba, which represents an improvement over previously reported Ba double-spike MC-ICP-MS methods at similar Ba consumption. We conclude that the double spike multi-isotope deconvolution approach can accurately assess and correct for elemental and hydride interferences for isotope systems with 5 or more stable isotopes suggesting that isotope systems such as Zr, Mo, Cd, Sn and Te might benefit from this strategy.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123209"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145785270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A survey of methoxyl and methyl isotopic clumping in a variety of biologic and synthetic materials","authors":"Rebekah S. Sprengel ,&nbsp;Max K. Lloyd ,&nbsp;Daniel A. Stolper","doi":"10.1016/j.chemgeo.2026.123243","DOIUrl":"10.1016/j.chemgeo.2026.123243","url":null,"abstract":"<div><div>Stable isotope measurements are important tracers of sample origins and formational conditions, including distinguishing between samples formed via synthetic vs. biological pathways. Here we present results that establish the ability of multiply substituted isotopologues, colloquially termed clumped isotopes, of methoxyl and methyl groups (Δ¹³CH₂D and Δ¹²CHD₂) can be used to distinguish biologically- from synthetically- generated materials and related to these (bio)chemical formational pathways. Specifically, we demonstrate that there is a large distinction between Δ¹³CH₂D values of plant-derived methoxyl groups vs. synthetic groups, including in the same molecule (e.g., vanillin). These distinctions are independent of bulk methoxyl and methyl hydrogen and carbon isotopic compositions. We discuss the processes that can generate these differences as well as implications for the study of methane clumped isotopes in the environment.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123243"},"PeriodicalIF":3.6,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145897545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}