Applied Geochemistry最新文献

{"title":"Provenance and geogenic modes of high-fluoride groundwater occurred in various sedimentary environments: constraints of hydrogeology and hydrogeochemstry","authors":"Guojie Feng ,&nbsp;Zhiqin Li ,&nbsp;Chunli Su ,&nbsp;Xianjun Xie ,&nbsp;Weili Ge ,&nbsp;Yiqun Gan ,&nbsp;Zhaohui Luo ,&nbsp;Kunfu Pi ,&nbsp;Hongjie Pan ,&nbsp;Yanhui Gao ,&nbsp;Yanmei Yang","doi":"10.1016/j.apgeochem.2025.106624","DOIUrl":"10.1016/j.apgeochem.2025.106624","url":null,"abstract":"<div><div>Hetao Plain is one of three major agricultural irrigation areas in China, where groundwater salinization and associated high fluoride concentrations (F⁻ &gt;1.5 mg/L) pose serious threats to ecological sustainable development. A total of 487 groundwater samples were collected from the Hetao Plain to explore the spatial variability, sources, and dominant hydrogeochemical processes controlling groundwater F⁻ enrichment. Furthermore, the genetic modes of high F⁻ groundwater occurring in different hydrogeological units were clarified and compared using hydrochemical analysis and factor analysis. The results show groundwater F⁻ concentrations range from &lt;0.05 mg/L (detection limit) to 7.83 mg/L, with 46.6 % and 7.9 % of samples in the Qiantao Plain and Houtao Plain, respectively, having concentrations exceeding 1.5 mg/L. High F- groundwater exhibited high spatial variability and occurred in shallow aquifers with depth less than 60 m, which is mainly regulated by the fluoride sources and hydrogeological conditions. Sediments in the Houtao Plain mainly originate from alluvial deposits of the Yellow River, whereas in the Qiantao Plain originate from fluoride-rich bedrocks/minerals of the eastern Yin Mountains. Different material sources are the primary factor causing spatial variability of groundwater F⁻ concentrations in the two plains. High F⁻ groundwater in the Qiantao Plain is characterized by leaching-enrichment type, while in the Houtao Plain is dominated by leaching-enrichment type in the piedmont alluvial-pluvial fan (Zone C) and a combination of leaching-enrichment type and evaporation-concentration type in the riparian zone of the Yellow River and north margin of the Ordos Plateau (Zone E), respectively. The vital factors responsible for F⁻ enrichment are abundant sources, favorable hydrogeological conditions, alkaline soda water type, and strong evaporation. The study clearly distinguished the difference in sediment material sources between the two adjacent plains, achieving a deepening understanding of the genetic models from the basin to specific hydrogeological units. These findings can provide a theoretical basis for safe groundwater supply in arid regions.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106624"},"PeriodicalIF":3.4,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518707","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":"Paleoenvironment-driven organic matter differential accumulation: New data from the Paleogene lacustrine shale in Yitong basin, NE China","authors":"Weixin Zhang ,&nbsp;Sandong Zhou ,&nbsp;Qiaoyun Cheng ,&nbsp;Ruibin Chen ,&nbsp;Hang Liu ,&nbsp;Xinyu Liu ,&nbsp;Hongbo Miao ,&nbsp;Dameng Liu ,&nbsp;Detian Yan ,&nbsp;Hua Wang","doi":"10.1016/j.apgeochem.2025.106627","DOIUrl":"10.1016/j.apgeochem.2025.106627","url":null,"abstract":"<div><div>The Paleogene Hothouse climate significantly affects the paleoenvironment and regional climate of lake basins globally. A Hothouse climate is recorded in the Paleogene Shuangyang Formation within Yitong Basin. The first member of the Shuangyang Formation forms excellent hydrocarbon source rocks. Under the influence of a Hothouse climate state during the Paleogene, the paleoenvironmental controls on organic matter accumulation within the Shuangyang shale remain to be fully understood. This study employs an integrated analysis of mineralogy, lithology, and organic/inorganic geochemistry to divide the Shuangyang shale into three parts: lower, middle, and upper. Paleoenvironmental conditions for each part are reconstructed using diverse geochemical proxies, and the differential accumulation of organic matter is explored. The findings indicate that the Shuangyang shale is rich in quartz mineral (average = 49.35 %), with the proportion of organic-rich shale (total organic carbon, TOC ≥ 2 wt. %) accounting for 60 %. A reducing environment and suitable salinity are the basic conditions for the preservation and accumulation of organic matter. The development of organic-rich shale is driven by a humid paleoclimate, strong terrigenous detrital concentration, and high paleoproductivity. Organic matter accumulation in the lower and upper parts is driven by middle-high paleoproductivity and strong terrigenous detrital concentration, respectively. The stable development of organic-rich shale in the middle part is driven by a humid paleoclimate, moderate terrigenous detrital concentration, and medium paleoproductivity. This study reveals the driving mechanisms behind organic matter differential accumulation in various sedimentary paleoenvironments, providing valuable insights for lacustrine shale oil exploration.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106627"},"PeriodicalIF":3.4,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518709","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":"Varied terrestrial sources of branched tetraether lipids in sediments of the Lower Bengal Fan affect the temperature reconstruction proxy","authors":"Chengpeng Sun ,&nbsp;Gang Hu ,&nbsp;Huawei Wang ,&nbsp;Zhiyuan Zhou ,&nbsp;Xupeng Hu ,&nbsp;Xinxin Li","doi":"10.1016/j.apgeochem.2025.106623","DOIUrl":"10.1016/j.apgeochem.2025.106623","url":null,"abstract":"<div><div>Sedimentary branched glycerol dialkyl glycerol tetraether (brGDGT) lipids are commonly used to reconstruct continental paleotemperatures. However, the influence of varied terrestrial sources of brGDGTs, either from highland or floodplain, in a river basin on paleotemperature reconstruction has not been addressed. In this study, brGDGT lipids were analyzed in a gravity core taken from the active channel of the Lower Bengal Fan to evaluate the source effect on paleotemperature reconstruction during three distinct stages over the past 15 ka: stage I (15–10 ka), stage II (10–2 ka), and stage III (2–0 ka). The positive correlation between smectite/(illite + chlorite) and methylation index of 5-methyl branched tetraethers (MBT’_5ME) (stage I: R² = 0.64, <em>p</em> &lt; 0.01; stages II and III: R² = 0.69, <em>p</em> &lt; 0.01) indicated that the reconstructed paleotemperatures were intimately associated with shifts in sediment sources. At stage I, enriched highland sediment sources with low smectite/(illite + chlorite) ratios at the low sea level during the Bølling-Allerød event led to an underestimation of the paleotemperature (15 °C) compared to the Younger Dryas (17 °C) event. During late stage II (6–2 ka), gradually waning highland sediments indicated by the increasing smectite/(illite + chlorite) ratio, along with rising sea level and deltaic subsidence, resulted in a progressive overestimation of the reconstructed temperatures (19–20 °C) than the early stage II (18 °C at 10–6 ka). Stage III (2–0 ka) marked an incrementally increasing contribution from highland sediments due to progressive river relocation, resulting in a cooling paleotemperature reconstruction from 20 °C to 18 °C. All pointed to the importance of distinguishing varied terrestrial sources of branched tetraether lipids in large-elevation river basins to reconstruct paleotemperature by the MBT’_5ME proxy.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106623"},"PeriodicalIF":3.4,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518700","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":"Geochemical evaluation of fluid-rock interactions between high-pH hydraulic fracturing fluid and carbonate-rich reservoirs: A case study of the Niobrara Formation, Denver-Julesburg Basin, Colorado, USA","authors":"Olivia Terry ,&nbsp;Derek Caro ,&nbsp;Tianxiao Shen ,&nbsp;Shaina Kelly ,&nbsp;Janet Dewey ,&nbsp;John P. Kaszuba","doi":"10.1016/j.apgeochem.2025.106613","DOIUrl":"10.1016/j.apgeochem.2025.106613","url":null,"abstract":"<div><div>Unconventional hydrocarbon reservoirs are commonly hydraulically fractured with acidified fresh water. Most development of unconventional reservoirs occurs in rural environments with little surface water, meaning fresh water is transported from other regions or is extracted from local groundwater and aquifers. Use of formation fluid extracted from active or depleted reservoirs has been proposed, however formation fluid is notoriously high in total dissolved solids, which is thought to be unfavorable for subsurface geochemical reactions. Additionally, some fluid stabilizers, which alter fluid viscosity, are less effective in fluid with high total dissolved solids. Gel-based fluid stabilizers, such as crosslink, are effective in high ionic strength fluids, however viscosity is best maintained at high pH (&gt;8). High-pH fracturing fluid interactions with reservoir rock have not been well studied compared to acidic fluids. Field studies can provide long-term insight into efficiency of high-pH fracturing fluid in reservoir rock, however geochemical reactions between reservoir rock and injected fluid are known to occur on the order of a few days, during well shut-in (days to weeks). Two laboratory experiments were performed to analyze the potential for geochemical reactions between reservoir rock and high-pH fracturing fluid within the shut-in timescale. Core from the Niobrara Formation (marl and chalk), a productive unconventional reservoir in the Denver-Julesburg Basin, Colorado, USA, and high-pH hydraulic fracturing fluid (pH = 10.1) were reacted at reservoir conditions (113 °C, 27.5 MPa) for ∼35 days. Temporal evolution of aqueous geochemistry and thermodynamic analysis of both experiments indicates 1) fluid accesses nanopores; 2) pH decreases to circumneutral values as geochemical reactions shift from fluid-to rock-dominated; and 3) no significant secondary precipitation is observed. The absence of secondary mineralization indicates limited reaction between high-pH hydraulic fracturing fluid and Niobrara Formation marl and chalk and suggests that geochemical fluid-rock interactions will not impact matrix porosity and permeability during extraction of fluids from unconventional reservoirs under similar conditions. Additionally, results are compared to acidic fracturing fluid studies to assess the response of carbonate-bearing reservoir rock to pH and relative concentrations of calcium and magnesium.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106613"},"PeriodicalIF":3.4,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518708","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":"Long-term emission of methane and ethane to the atmosphere from hybrid natural seepage and well leakage in the Sărmăşel gas field (Romania)","authors":"Eduard Ghiorghiu ,&nbsp;Iulia Ajtai ,&nbsp;Ildiko M. Martonos ,&nbsp;Mustafa Hmoudah ,&nbsp;Alexandra Orban ,&nbsp;Alexandru Lupulescu ,&nbsp;Liana Spulber ,&nbsp;Alexandra I. Cozma ,&nbsp;Ștefan Șfabu ,&nbsp;Roxana Moga ,&nbsp;Călin Baciu ,&nbsp;Giuseppe Etiope","doi":"10.1016/j.apgeochem.2025.106614","DOIUrl":"10.1016/j.apgeochem.2025.106614","url":null,"abstract":"<div><div>Fossil methane and ethane, produced and accumulated in sedimentary basins, enter the atmosphere through both artificial leakage during gas-oil production activity (fugitive emissions) and natural seepage (gas naturally migrating to the surface). Well leaks, such as accidental blowouts during or after drilling, can be easily recognized by direct ground-based observations, and prompt remedial actions render them as short-term gas emission events, with no significant atmospheric impact. We report a complex case of long-term fugitive emission that developed away from the drilling site, with gas exhaling from the ground together with natural gas seepage. The site refers to the first producing gas well in Transylvania, drilled in 1909 in the Sărmăşel microbial gas field. We combined (a) a historical reconstruction of the events, based on early documents of that period, (b) geological setting analysis (stratigraphy and fault locations), and (c) present-day observation of the surface gas manifestations, through measurements of methane and ethane flux from the ground, and their concentration in the soil, shallow aquifer and surface waters. We deduce that after the closure of the well in 1911, due to gas pressure increase, the gas leaked from the well bottom, penetrated anticlinal strata and entered a natural seepage system along a fault. The leaked, stray gas mixed with the gas naturally migrating to the surface from the underlying reservoirs, producing surface craters with burning vents, still active today. It is likely that the natural seepage system amplified and is still sustaining the post-drilling leak. We estimated that, since 1911, the total amounts of methane and ethane injected from the ground to the atmosphere are at least in the order of 10⁴ t and one t, respectively. Sărmăşel gas manifestation, today leaking &gt;20 kg CH₄ h⁻¹, is a super-emitter according to the definition used for fugitive emissions in Romania. This study represents an example of the risk of uncontrolled, persistent and elusive fugitive emissions that may occur when drilling is executed within a natural seepage system. The presence of ethane in the aquifer and soil supports the hypothesis that the Transylvanian Basin may host a deep thermogenic system.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106614"},"PeriodicalIF":3.4,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145465127","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":"Radon levels in soil and in groundwater in the Alhama de Murcia fault area, Spain","authors":"Victòria Moreno ,&nbsp;Joan Bach ,&nbsp;Mario Zarroca ,&nbsp;Eulàlia Masana ,&nbsp;Lluís Font ,&nbsp;Rogelio Linares","doi":"10.1016/j.apgeochem.2025.106612","DOIUrl":"10.1016/j.apgeochem.2025.106612","url":null,"abstract":"<div><div>Radon and CO₂ in groundwater, radon and thoron in soil, soil radon exhalation rates, and electrical resistivity imaging were measured in the Alhama de Murcia Fault area. The study aims to (i) characterize radon levels in groundwater and soil and (ii) assess whether variations in gas emissions are related to the presence of an active fault. Forty water sampling points exhibited ²²²Rn concentrations ranging from 0.4 to 66.8 Bq/L, while 22 soil points along two profiles crossing the fault showed low annual mean values of (8 ± 1) kBq m⁻³ and (12 ± 2) kBq m⁻³. Soil radon exhalation rates at the two profiles, (36 ± 8) and (53 ± 12) Bq m⁻² h⁻¹, respectively, are consistent with these concentrations. Spatial variability of soil radon along both profiles, [1–22] kBq m⁻³, appears associated with the main fault location. Temporal variations of ²²²Rn recorded at a monitoring station from early 2013 to mid-2015 closely match punctual measurements. While fluctuations are largely controlled by barometric pressure and atmospheric temperature, detailed analyses combining multiple radon anomaly detection methods indicate a possible influence of nearby seismic events.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106612"},"PeriodicalIF":3.4,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145465125","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":"Implementation Pitfalls for carbonate mineral dissolution — A technical note","authors":"Fiona J. Weiss,&nbsp;Leon Keim,&nbsp;Kai Wendel,&nbsp;Holger Class","doi":"10.1016/j.apgeochem.2025.106611","DOIUrl":"10.1016/j.apgeochem.2025.106611","url":null,"abstract":"<div><div>In reactive transport modeling, an accurate understanding of reaction rates is essential; discrepancies in parameter reporting can greatly affect simulation results. This technical note identifies an issue with the reporting of rate parameters for carbonate mineral dissolution in a widely used database for reactive transport modeling based on Palandri and Kharaka (2004). Specifically, the reaction order was reported with respect to the partial pressure <span><math><mrow><mi>P</mi><mrow><mo>(</mo><msub><mrow><mi>CO</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></mrow></mrow></math></span> rather than the activity of <span><math><mrow><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msub><msubsup><mrow><mi>CO</mi></mrow><mrow><mn>3</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></mrow></math></span>, causing a considerable overestimation of reaction timescales. We demonstrate the implications of this error by simulating a calcite dissolution batch experiment using Reaktoro and DuMuX and comparing the results to experimental data. By adjusting the parameter to align with established literature, we demonstrate an improved fit between simulated and experimental data. Discrepancies in reaction timescales were reduced by an order of magnitude, emphasizing the importance of regular validation of simulations with experimental data.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106611"},"PeriodicalIF":3.4,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555196","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 sub-liter pretreatment method for Orbitrap–based freshwater phosphate oxygen isotope measurement","authors":"Zhao Wei ,&nbsp;Baoying Wang ,&nbsp;Longchen Zhu ,&nbsp;Yihang Hong ,&nbsp;Zhenfei Wang ,&nbsp;Hao Yan ,&nbsp;Yongbo Peng ,&nbsp;Shohei Hattori ,&nbsp;Huiming Bao","doi":"10.1016/j.apgeochem.2025.106610","DOIUrl":"10.1016/j.apgeochem.2025.106610","url":null,"abstract":"<div><div>Phosphate oxygen isotope composition (<em>δ</em>¹⁸O(PO₄³⁻)) provides critical insights into the sources and transformation processes of phosphorus in aquatic environments. However, the low PO₄³⁻ concentration (&lt;1 μM) in natural freshwater necessitates large sample volumes (25–100 L) and tedious procedures in the conventional <em>δ</em>¹⁸O(PO₄³⁻) analysis method that uses thermal conversion/elemental analysis linked to a gas–source isotope-ratio mass spectrometer (TC/EA–IRMS). Here, we report a method for analyzing <em>δ</em>¹⁸O(PO₄³⁻) using sub-liter volumes (∼1 L) of freshwater. The approach uses a well-established zirconium-oxide-gel method to adsorb dissolved PO₄³⁻, followed by purification of PO₄³⁻ via anion exchange resin and isotope measurement by Electrospray Ionization Orbitrap Mass Spectrometry (ESI–Orbitrap–MS). The whole pretreatment procedure results in a <em>δ</em>¹⁸O(PO₄³⁻) accuracy of ±0.8 ‰, within the analytical uncertainty of the ESI–Orbitrap–MS measurement. Calibration with TC/EA–IRMS produced nearly a 1:1 regression (slope 0.96, residual &lt;0.9 ‰). Tests on freshwater samples from a natural lake achieved an accuracy of ±0.3 ‰. The method reduces sample volume by three orders of magnitude compared to the TC/EA–IRMS method, opening up opportunities to trace PO₄³⁻ cycling and source apportionment in an unprecedented temporal and spatial resolution.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"194 ","pages":"Article 106610"},"PeriodicalIF":3.4,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463422","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":"Hydrogeochemical mechanisms of ore-bearing layer clogging during acid ISL of uranium","authors":"Xuefeng Liu ,&nbsp;Jinhui Liu ,&nbsp;Yongguo Xing ,&nbsp;Yihan Yang ,&nbsp;Ruyi Wang","doi":"10.1016/j.apgeochem.2025.106594","DOIUrl":"10.1016/j.apgeochem.2025.106594","url":null,"abstract":"<div><div>This study examined the hydrogeochemical mechanisms of permeability reduction during acid in situ leaching (ISL) in the C12 mining area of the Bayan Ula uranium deposit. It analyzed the spatiotemporal evolution of leaching solution chemistry and conducted hydrogeochemical modeling. The key processes influencing permeability were identified. SO₄²⁻ concentration decreased significantly over time. Ca²⁺ concentration initially increased and then declined. This change resulted from the enhanced dissolution of calcium-bearing minerals and subsequent gypsum precipitation. Spatially, Ca²⁺ showed an increasing and then decreasing trend along the flow path. This pattern corresponded to intensified mineral reactions. SO₄²⁻ progressively decreased along the pathway, with the main acid consumption zone located downstream. PHREEQC simulations indicated that Ca²⁺ mainly existed as free Ca²⁺ and CaSO₄ complexes. Gypsum formation occurred when Ca²⁺ exceeded the precipitation threshold (Ca²⁺_{b, CaSO4}). The saturation index (SI_CaSO4) and reaction condition index (RCI_Ca²⁺) showed that the tendency for gypsum precipitation weakened over time but increased downstream. This change was driven by pH-induced variations in SO₄²⁻ activity. These findings aligned with observed leaching solution chemistry. They confirmed that gypsum precipitation, especially in downstream regions, played a critical role in reducing ISL permeability.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106594"},"PeriodicalIF":3.4,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733230","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":"Foreword to the virtual special issue on the “18th International conference on the chemistry and migration behaviour of actinides and fission products in the geosphere, MIGRATION 2023”","authors":"Bernd Grambow ,&nbsp;Horst Geckeis ,&nbsp;Gilles Montavon ,&nbsp;Tomo Suzuki-Muresan ,&nbsp;Xavier Gaona","doi":"10.1016/j.apgeochem.2025.106608","DOIUrl":"10.1016/j.apgeochem.2025.106608","url":null,"abstract":"","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"194 ","pages":"Article 106608"},"PeriodicalIF":3.4,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517281","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}