Applied Geochemistry最新文献

{"title":"Mineralogical constraints on carbon deportment in phosphate ores: Implications for decarbonizing ore processing","authors":"Abdelaziz Zine ,&nbsp;Abdellatif Elghali ,&nbsp;Radouan El Bamiki ,&nbsp;Nouhaila Attalir ,&nbsp;Mustapha Mouflih ,&nbsp;Jérémie Aubineau ,&nbsp;Fleurice Parat ,&nbsp;Manuel Munoz ,&nbsp;Oussama Khadiri Yazami ,&nbsp;Jean-Louis Bodinier","doi":"10.1016/j.apgeochem.2025.106672","DOIUrl":"10.1016/j.apgeochem.2025.106672","url":null,"abstract":"<div><div>The release of CO₂ from carbon-bearing minerals during phosphate ore processing contributes to industrial emissions but remains poorly quantified. This study examines the Bouchane phosphate deposit, part of the Gantour Basin in Morocco, which consists of Upper Cretaceous–Paleogene sedimentary phosphates. The objective is to constrain the proportions and deportment of carbon within its mineral phases and assess their contribution to CO₂ release during beneficiation and acidulation. For this purpose, 20 representative samples from a stratigraphic section of the deposit were analyzed for petrographic composition, bulk mineralogy by X-ray diffraction, bulk geochemistry by inductively coupled plasma optical emission spectroscopy (ICP-OES), and total carbon by induction furnace, complemented by in-situ microanalyses using an electron probe micro-analyzer (EPMA) and quantitative automated mineralogy with a TESCAN Integrated Mineral Analyzer (TIMA). Moreover, the modal composition of the studied samples was determined using various approaches such as quantitative X-ray diffraction (QXRD), quantitative automated mineralogy (QAM), element-to-mineral conversion (EMC), and total inversion (TI). The studied samples were predominantly composed of phosphatic coated grains, peloids, coprolites, and skeletal particles. The chemistry of these sediments varied along the stratigraphic section, marked by a dominance of inorganic carbon compared to organic carbon, with a mean content of 11.38 ± 4.58 wt% and 0.68 ± 0.03 wt%, respectively. The developed calculated mineralogy techniques (EMC, TI) proved successful in accurate quantification of the modal composition of the phosphate sediments. Automated mineralogy by TIMA provided a quantification of the percentage of problematic locked carbonates within phosphatic grains, with values below 3 %. These grains were predicted to hold 11 % of the CO₂ in carbonate fluorapatite (CFA), and 0.3 % and 0.1 % in calcite and dolomite, respectively. The remaining carbonate phases are removed during washing and flotation. This study shows that adopting holistic approaches in phosphate mining is efficient for developing rapid, low-cost techniques for mineralogical characterization (EMC, TI) and indicates that phosphate rock processing results in limited in situ CO₂ release from carbonate minerals.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106672"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 review of Al substitution on the structures and properties of iron (oxyhydr)oxides and their environmental implications","authors":"Junkun Yan ,&nbsp;Jingjing Hu ,&nbsp;Lingyi Li ,&nbsp;Wei Cheng","doi":"10.1016/j.apgeochem.2025.106653","DOIUrl":"10.1016/j.apgeochem.2025.106653","url":null,"abstract":"<div><div>Aluminum (Al) substitution for Fe(III) in iron (oxyhydr)oxides is a widespread phenomenon that significantly modifies the minerals' physicochemical structural properties and reactivity, thereby influencing the environmental behavior of contaminants. Despite the importance of Al-substituted iron (oxyhydr)oxides in geochemical processes, a comprehensive analysis of their structural properties and reactivity has been lacking. This review critically examines the effects of Al substitution on iron (oxyhydr)oxide crystal structure, morphology, surface charge, hydroxyl group characteristics, and recrystallization dynamics. We then elucidate how these structural alterations modulate the adsorption capacity for key environmental contaminants (heavy metals, metalloids, organic compounds, inorganic anions) and influence redox and catalytic processes crucial for contaminant transformation. This work provides essential insights for predicting contaminant behavior in diverse geological settings and inform the design of tailored remediation technologies. Future research directions are proposed to advance understanding of Al-substituted iron (oxyhydr)oxides in critical environmental processes.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106653"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145789479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling transport of natural tracers through a Mesozoic aquitard sequence in northern Switzerland","authors":"Jin Ma ,&nbsp;Thomas Gimmi ,&nbsp;Paul Wersin ,&nbsp;Daniel Traber ,&nbsp;Michael Schnellmann","doi":"10.1016/j.apgeochem.2025.106654","DOIUrl":"10.1016/j.apgeochem.2025.106654","url":null,"abstract":"<div><div>Analysing and modelling profiles of natural tracers in rock porewater contribute substantially to the understanding of palaeo-transport processes in clay rocks. Following a recent deep-drilling campaign in northern Switzerland, a large dataset from eight boreholes has become available. It reveals detailed rock and porewater characterisation and provides insights into the investigated 600-700 m-thick Mesozoic succession, which includes a large central aquitard sequence with more than 100 m thick Opalinus Clay. The aquitard sequence is sandwiched between the Malm aquifer (towards the east) or the Hauptrogenstein aquifer (HRS, towards the west) at the top and the Keuper or Muschelkalk aquifers at the base. This study aimed to model and reproduce the high-resolution profiles of four different natural tracers (δ¹⁸O, δ²H, Cl⁻, and Br⁻) from these boreholes using a one-dimensional transport model. The model incorporated diffusion properties dependent on temperature, clay-mineral content, and formation-specific anion-accessible porosities. Good agreements were found between the modelled and measured profiles considering diffusive transport and consistent evolution times (i.e., times when groundwater composition changed) for all four tracers. These times were estimated individually for each borehole, suggesting values between 0.1 and 0.7 Ma for the Keuper aquifer, longer times (mostly several Ma, range of 0.6–3 Ma) for the Malm aquifer, and shortest times (mostly less than 150 ka, range of 0.02–0.3 Ma) for the Muschelkalk aquifer. These estimates are broadly consistent with the current knowledge on the palaeo-hydrogeology of the studied region. Extensive sensitivity analyses were performed to assess the impact of various modelling assumptions and simplifications on the fitting quality and estimated evolution times. Variations with regard to assumed initial conditions (within plausible ranges) and palaeo temperatures had only minor effects, while variations of diffusion coefficients or positions of conductive zones can affect local profile shapes and thus evolution times. Finally, no evidence of potential cross-formation flow between the overlying and underlying aquifers (Malm and Keuper) could be identified from simulations including advective transport.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106654"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145789482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stability of barite in thermochemical sulfate reduction: implications for primeval organic component preservation and metal sulfide mineralization","authors":"Yuan Wei ,&nbsp;Qian Wan ,&nbsp;Wenxuan Hu ,&nbsp;Xiaolin Wang","doi":"10.1016/j.apgeochem.2025.106666","DOIUrl":"10.1016/j.apgeochem.2025.106666","url":null,"abstract":"<div><div>Thermochemical sulfate reduction (TSR) is a common organic-inorganic interaction where sulfates react with hydrocarbons at elevated temperatures, producing reduced sulfur and oxidized carbon. The stability of barite in TSR is a critical scientific question because barite-hosted inclusions are reported to record primeval organic matters and barite can be involved in the formation of Sedimentary Exhalative and Mississippi-Valley type deposits. Here we performed systematic hydrothermal experiments and thermodynamic simulations to identify the key factors controlling TSR between barite and hydrocarbons. Results show that in anhydrous and neutral aqueous environments, barite and hydrocarbons can coexist stably at temperatures below 150 °C. Such condition is comparable with that reported for the formation of ∼3.5 Ga barite in Pilbara Craton, Western Australia, indicating that barite-hosted inclusions can record original information for Archean life evolution. At higher temperature and low pH conditions, barite can react with hydrocarbon to generate H₂S and CO₂. Fluid acidity (i.e., H⁺ concentration) and temperature are the most prominent factors controlling the involvement of barite in TSR. Therefore, consumption of preexisting H₂S (either TSR or other origin) by precipitation of metal sulfides (e.g., sphalerite and galena) can generate excess H⁺, which favors the involvement of barite in TSR. Obviously, barite can serve as a sulfur source for the formation of metal sulfide deposits. In conclusion, our findings offer new insights into researches of early Earth environments and the mineralization mechanisms of metal deposits.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106666"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resolving false positive Eu anomaly in seep carbonates with high Ba/Sm ratio using DGA resin separation","authors":"Xudong Wang ,&nbsp;Lanlan Zhang ,&nbsp;Tongtong Bai ,&nbsp;Jean-Alix Barrat ,&nbsp;Zhaoyang Wang ,&nbsp;Zice Jia ,&nbsp;Dong Feng","doi":"10.1016/j.apgeochem.2025.106670","DOIUrl":"10.1016/j.apgeochem.2025.106670","url":null,"abstract":"<div><div>The contents and distribution patterns of rare earth elements (REEs) are powerful tools for reconstructing fluid sources and redox conditions in marine sedimentary environments. However, their accurate determination in carbonate rocks is often complicated by low REE abundances and high barium (Ba) contents, which cause severe isobaric interference with europium (Eu) during conventional ICP-MS analysis due to the formation of BaO⁺ or BaOH⁺ polyatomic ions. In this study, we applied a validated DGA resin separation technique to analyze REEs from 30 Ba-rich authigenic carbonate samples from nine seep sites in the Gulf of Mexico. Before and after DGA separation, REE analyses were conducted on both bulk carbonate rock and carbonate fraction of carbonate rock (hereafter carbonate fraction). Ba contents ranged from 201 ppm to 91200 ppm in the bulk carbonate rock, and from 28 ppm to 1700 ppm in the carbonate fraction. Prior to separation, Eu/Eu∗ values ranged from 1.40 to 80.49 in bulk rock and from 1.44 to 17.65 in the carbonate fraction, with strong correlation to Ba/Sm ratios, indicating Ba-induced analytical artifacts. After DGA resin separation, Eu/Eu∗ values decreased to 1.10–1.16 in bulk rock and 1.11–1.22 in the carbonate fraction, confirming the elimination of false Eu anomaly. These results demonstrate that Ba-related interference can lead to substantial misinterpretation of REE data in Ba-rich samples. We advocate for routine chemical separation of REEs from matrix elements prior to ICP-MS analysis to ensure accurate paleoenvironmental reconstructions in seep and other Ba-enriched sedimentary settings.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106670"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of salinity on nitrogen cycling and microbial community functional potential in groundwater of the Yellow river delta","authors":"Huan Wang ,&nbsp;Chuanshun Zhi ,&nbsp;Yufei Jiao ,&nbsp;Dan Xu ,&nbsp;Wenfeng Gao ,&nbsp;Yawei Kou ,&nbsp;Xiancang Wu ,&nbsp;Jing Bai ,&nbsp;Hui Mu ,&nbsp;Houliang Lu ,&nbsp;Xiaonong Hu","doi":"10.1016/j.apgeochem.2025.106669","DOIUrl":"10.1016/j.apgeochem.2025.106669","url":null,"abstract":"<div><div>Microorganisms in shallow groundwater of river deltas play a key role in nitrogen cycling, yet little is known about this process in high-salinity regions. This study examines how salinity affects nitrogen cycling and microbial function in the Yellow River Delta's high-salinity groundwater. Through combined hydrochemical, microbial, and genetic analyses, the study reveals that groundwater is high saline, mainly of the Na–Cl type, with ammonium as the dominant nitrogen form under reducing conditions. Microbial communities vary with salinity and redox conditions, and nitrogen cycling is mainly driven by DNRA and denitrification. Functional genes related to nitrogen metabolism strongly correlate with ammonium levels, emphasizing ammonium's regulatory role. Different hydrochemical factors shape nitrogen cycling at varying salinities: pH, I⁻, and Mg²⁺ at low salinity; K⁺ and sulfide at medium salinity; and TDS, Cl⁻, SO₄²⁻, and Na⁺ at high salinity. Overall, reductive pathways dominate, with denitrification (35.88 %) and DNRA (31.03 %) as the main processes. Under varying salinity conditions, nitrogen cycling pathways shift significantly: low-salinity favors nitrogen fixation, nitrification and DNRA, promoting both nitrogen input and loss; medium-salinity supports active nitrogen turnover through enhanced nitrification, denitrification, and ANRA; while high salinity leads to DNRA dominance, ammonium accumulation, and reduced nitrogen removal due to suppressed nitrification and denitrification. High-salinity selects for DNRA-performing, salt-tolerant microbes, enriching DNRA genes (<em>narGHI, nirBD</em>), while denitrification genes (<em>nosZ, nirK</em>) are more abundant at lower salinities.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106669"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New insights on the Pb isotopic compositions of drinking water lead pipes in the United States","authors":"George D. Kamenov ,&nbsp;Sean Scott","doi":"10.1016/j.apgeochem.2025.106639","DOIUrl":"10.1016/j.apgeochem.2025.106639","url":null,"abstract":"<div><div>Compilation of high-precision Pb isotope data for Pb pipes can be used to identify human exposure to Pb from lead service lines (LSLs) in the USA. Furthermore, as the Pb used in LSLs was most likely obtained from the same ore deposits as lead used in other objects and materials, the Pb pipe data should provide information about the overall isotopic composition of the U.S. industrial Pb. This work presents new MC-ICP-MS Pb isotope data for 50 Pb pipes, all harvested from the state of Wisconsin. The new data show virtually identical isotopic compositions as the previously published MC-ICP-MS data for USA Pb pipes, indicating that most likely no specific geographical variations can be expected in LSLs Pb isotopes in the USA. Furthermore, the Pb pipe isotope data encompass almost the whole isotope range observed in major domestic and international Pb ore deposits. Therefore, the Pb pipe data should be representative of the Pb isotope range of industrial Pb in the USA. The compiled data reveal the existence of two major Pb isotope clusters. Cluster I is composed of lead obtained from various Pb deposits, including imported lead. Cluster II is composed exclusively of domestic lead obtained from the Mississippi Valley Type ore deposits, and potentially is unique to USA industrial Pb isotope signal. Comparison of the Pb pipe data to USA MC-ICP-MS human blood Pb reveals that most individuals, not exposed to Pb from LSLs, do not fall within the two isotope clusters. Therefore, the identified clusters, in addition to the overall Pb isotope linear trend, can potentially be used in large-scale epidemiological studies to decipher if human Pb exposure in a given region is from LSLs or other sources.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106639"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Provenance of oilfield brines and vertical connectivity of Middle to Upper Jurassic sequence in eastern Saudi Arabia","authors":"Peter Birkle ,&nbsp;Ahmed J. Zayer","doi":"10.1016/j.apgeochem.2025.106673","DOIUrl":"10.1016/j.apgeochem.2025.106673","url":null,"abstract":"<div><div>Knowledge of reservoir connectivity is crucial for optimizing oil recovery, accurately estimating reserves, planning well placement, and improving economics of an oil field. This study combines hydrochemical (major, minor, trace elements) and multi-isotopic techniques (δ²H, δ¹¹B, δ¹³C, ¹⁴C, δ¹⁸O_H2O, δ¹⁸O_SO4, δ³⁷Cl, δ⁸¹Br, δ³⁴S_SO4, ⁸⁷Sr/⁸⁶Sr) on oilfield brines to define reservoirs dynamics by tracing fluid provenance and migration. As case study, preserved bottom-hole water samples were recovered along a 1930’ vertical column of seven groundwater horizons from a Middle to Upper Jurassic carbonate-anhydrite sequence in an exploratory well in the eastern region of Saudi Arabia. Geochemical fluid homogeneities reveal hydraulic connectivity between the Lower Tithonian and Upper Kimmeridgian sequence, suggesting the presence of a single reservoir. Isotopic heterogeneities reveal sealing conditions between underlying Lower Kimmeridgian, Oxfordian (Hanifa), and Bathonian (Upper Dhruma) groundwater systems. Interlayered anhydrite strata resulted in possessing ambivalent hydrodynamic functionalities, either as conduits or seals. Studied formation waters are composed of Na–Cl to Na–Ca–Cl water type with a descending salinity from 210,500 mg/L (Tithonian) to 147,800 mg/L (Bathonian). Measured ¹⁴C concentrations from 2.01 pmC to 18.77 pmC point to recharge of the Jurassic sequence by infiltrating surface water during Late Pleistocene and Early Holocene, causing the mixing and partial replacement between 37 % and 55 % of fossil oilfield brine. A positive vertical trend of δ¹⁸O_SO4 - δ³⁴S_SO4 ratios, δ¹³C_PDB values between +8.4 ‰ and +16.2 ‰, and depleted δ¹¹B ratios reveal thermocatalytic sulfate reduction, methane production, and desorption of clay material, respectively, as major secondary water-rock interaction processes. As practical benefit, formation water analyses provide a low-cost and low-risk complementary tool to expensive and failure-prone production logging tools for evaluating reservoir conditions. The geochemical detection of hydraulic connectivity or compartmentalization between stratigraphic units represents a complimentary tool to trace the analogue migration of hydrocarbons within single or multiple pay zones.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106673"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinetic model reveals microbial-mediated hydrogen consumption and abiotic mineral reactions jointly control hydrogen depletion during geological storage","authors":"Dongfang Ke ,&nbsp;Weiqiang Feng ,&nbsp;Peng Liao ,&nbsp;Rong Li ,&nbsp;Ruina Xu ,&nbsp;Yu-Min Chou ,&nbsp;Peixue Jiang","doi":"10.1016/j.apgeochem.2025.106649","DOIUrl":"10.1016/j.apgeochem.2025.106649","url":null,"abstract":"<div><div>Underground hydrogen storage (UHS) in porous reservoirs faces biogeochemical challenges such as microbial hydrogen consumption and the generation of secondary gases, which can significantly compromise storage efficiency. To address critical knowledge gaps concerning the interactions between hydrogen, minerals, and microbes under kinetic parameter uncertainty, this study develops a novel co-simulation framework coupling MATLAB with Phreeqc. This integrated model combines kinetic formulations for mineral dissolution and precipitation (e.g., calcite and gypsum), microbial metabolism (e.g., sulfate reduction and methanogenesis), and thermodynamic gas-liquid equilibrium to simulate the complex gas-water-rock interactions during UHS. Simulation results reveal that hydrogen loss (&lt;0.22 %) and purity degradation (&lt;0.0002 %) are negligible under typical anaerobic reservoir conditions, constrained by an intrinsic microbial kinetic threshold. Substantial hydrogen consumption occurs only when the maximum specific reaction rate (<em>V</em>_max) exceeds 10^−4.5 s⁻¹; below this value, hydrogen depletion remains minimal irrespective of variations in mineral reactivity, mineral content, or initial biomass concentration. Abiotic mineral dissolution plays a pivotal role in sustaining microbial activity by supplying essential dissolved inorganic carbon (as a carbon source) and electron acceptors (e.g., SO₄²⁻, HCO₃⁻). Furthermore, biomass accumulation exhibits self-limiting behavior due to pore-space constraints, indicating limited effectiveness of post-cycle biomass removal strategies. However, under high-kinetic regimes, severe bioclogging and significant hydrogen loss can occur, highlighting the necessity of proactive microbial metabolic suppression to ensure the long-term viability of UHS operations.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106649"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling stress-mediated fluid-fault interactions in 2021–2022 seismic sequence: Insights from unsupervised machine learning and multiparametric hydrochemical anomalies in Xianshuihe fault zone","authors":"Yucong Yan ,&nbsp;Zheming Shi ,&nbsp;Xiaocheng Zhou ,&nbsp;Guangcai Wang ,&nbsp;Zuochen Zhang ,&nbsp;Yunfei Bai ,&nbsp;Zhaojun Zeng ,&nbsp;Bingyu Yao ,&nbsp;Yuwen Wang ,&nbsp;Miao He ,&nbsp;Jiao Tian ,&nbsp;Ruibin Li ,&nbsp;Han Yan","doi":"10.1016/j.apgeochem.2025.106635","DOIUrl":"10.1016/j.apgeochem.2025.106635","url":null,"abstract":"<div><div>Earthquake-related hydrochemical changes in thermal springs have been widely observed, yet the temporal dynamics and controlling mechanisms of pre- and post-seismic hydrochemical changes remains poorly constrained. By employing unsupervised machine learning (SOM-KM), this study investigates earthquake-induced changes of major elements, trace elements, and hydrogen-oxygen isotopes by high-frequency monitoring data in two thermal springs (XXX and LTG) along the Xianshuihe fault zone during the 2021–2022 Ms ≥ 6.0 earthquake sequence. The result shows that: the XXX spring (Moxi segment) exhibited consistent co-seismic dilution of major ions (Na⁺, K⁺, Cl⁻, HCO₃⁻) and trace elements, attributed to shallow fracture opening under low normal stress (200–400 MPa), thereby facilitating meteoric water recharge (81–89 % mixing ratio). Conversely, the LTG spring (Kangding segment) showed enrichment of deep-sourced constituents of pre-seismic major elements (Na⁺, K⁺, Cl⁻, HCO₃⁻) surges during the 2021 Luxian <em>M</em>s6.0 earthquake, and post-seismic trace element fluctuation in 2022 Ms ≥ 6.0 earthquake sequence, driven by high stress (400–600 MPa) enhancing deep fracture dilation, fluid ascent, and water-rock interaction (obvious δ¹⁸O drift). Cross-analysis of hydrogeochemical signatures with geological and geophysical evidence demonstrates that earthquake-induced hyrochemical anomalies are governed by (1) regional tectonics stress; (2) fault-segment heterogeneity; (3) fluid pathway reorganization and water-rock interaction dynamics. This work advances the understanding of fault-zone fluid response mechanisms to seismicity and offers novel insights into crustal fluid-tectonic interactions during earthquake cycles.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106635"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}