Applied Geochemistry最新文献

{"title":"Iodine incorporation into calcium phosphate minerals at hydrothermal conditions","authors":"Ángel Jiménez-Arroyo ,&nbsp;Rinat I. Gabitov ,&nbsp;Artas Migdisov ,&nbsp;Alberto Pérez-Huerta ,&nbsp;Juejing Liu ,&nbsp;Xiaofeng Guo ,&nbsp;Hongwu Xu ,&nbsp;Padmanava Dash ,&nbsp;Hakim Boukhalfa","doi":"10.1016/j.apgeochem.2025.106486","DOIUrl":"10.1016/j.apgeochem.2025.106486","url":null,"abstract":"<div><div>Among the numerous radionuclides generated by nuclear fission, radioiodine (¹²⁹I) poses a long-term environmental and health threat due to its high mobility, solubility, radiotoxicity, and 15.7 Ma half-life. Even though relatively small amounts of radioiodine are generated per ton of spent fuel, its accumulation has exponentially increased since the inception of the nuclear age. Many approaches for the immobilization of radioiodine have been extensively investigated. These methods, however, are still limited by thermodynamic instability, high costs, slow kinetics, and volatile loss during vitrification. Given the relationship and similarities of iodine species with other anions present in apatite, such a mineral still represents a promising host for the safe disposal of radioiodine. However, the interaction between aqueous iodine species and the mineral apatite at hydrothermal conditions remains a knowledge gap. This work evaluated the immobilization of iodate (IO₃⁻) and iodide (I⁻) from solutions by calcium phosphate minerals (apatite and monetite) at 39 and 200 °C. The performed analysis of our experimental solids encompassed electron microprobe analysis (EMPA), scanning electron microscopy coupled with energy dispersion spectroscopy (SEM-EDS), X-ray diffraction (XRD), and synchrotron X-ray absorption spectroscopy (XAS). In addition, the experimental solutions were analyzed using UV–visible spectrophotometry (UV–Vis) before and after the experiments to track redox changes if any, of the iodine species initially used and to derive iodine concentrations. Iodine concentrations acquired from EMPA (for solids) and UV–Vis (for solutions) were used to calculate the apparent Nernst partition coefficient of iodine as <span><math><mrow><msup><mi>D</mi><mi>I</mi></msup><mo>=</mo><mfrac><msub><mi>I</mi><mrow><mspace></mspace><mrow><mo>(</mo><mrow><mi>a</mi><mi>p</mi><mi>a</mi><mi>t</mi><mi>i</mi><mi>t</mi><mi>e</mi></mrow><mo>)</mo></mrow></mrow></msub><msub><mi>I</mi><mrow><mo>(</mo><mrow><mi>f</mi><mi>l</mi><mi>u</mi><mi>i</mi><mi>d</mi></mrow><mo>)</mo></mrow></msub></mfrac></mrow></math></span>. The highest iodine concentration found in apatite was 6.0 wt% when an iodate-bearing NaCl solution was used as the crystal growth medium. In experiments where iodide-bearing solutions were used, iodine concentrations in apatite ranged from 0.04 to 0.45 wt%. Partitioning data show that IO₃⁻ is more compatible with apatite (D &gt; 1) while I⁻ is less compatible (D &lt; 1). The results indicate that iodine incorporation into apatite is favorable at oxidizing conditions.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106486"},"PeriodicalIF":3.1,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144502781","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":"Molecular markers of carbazole compounds in crude oils from NW China: Implications for organic facies and depositional paleoenvironment","authors":"Chuanyuan Wang ,&nbsp;Wentong Wang ,&nbsp;Zhaoquan Bao ,&nbsp;Zhongping Li ,&nbsp;Panjun Han","doi":"10.1016/j.apgeochem.2025.106484","DOIUrl":"10.1016/j.apgeochem.2025.106484","url":null,"abstract":"<div><div>The Tarim, Qaidam, and Ordos basins, located in Northwest China, are recognized as three significant oil and gas reservoirs, and a comprehensive geochemical analysis of the crude oils sourced from these basins has been conducted to elucidate the various factors, that influence the concentrations and distribution patterns of carbazole compounds. The average concentration of carbazole compounds in fresh lacustrine facies crude oil is significantly higher compared to those from salt lake facies and marine facies. Furthermore, salinity exerts a significant influence on the alkylation of methylcarbazole, whereas its effect on dimethylcarbazole alkylation is comparatively less pronounced. Under the premise of fully correcting the migration distance, the sedimentary environment (salinity, redox conditions) plays a dominant role in the distribution of carbazole compounds. Sedimentary facies and depositional environments also affect the total nitrogen concentrations and maturity-related parameters, such as the 1-MC/4-MC ratio. However, these factors minimal influence on migration indicators, such as the ratios of 3-MC/4-MC, 1,8-DMC/2,7-DMC, 1,3-DMC/2,7-DMC, and [a]/([a] + [c])-BC, which serve as reliable diagnostic tools for inferring the sedimentary environment. These findings indicate that carbazole compounds can serve as valuable tools for oil-source correlation studies.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106484"},"PeriodicalIF":3.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144511112","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":"Comparing greenhouse gas stable isotopes from different sampling methods: Aquifer groundwater and coal seam gas production waters","authors":"Julie K. Pearce ,&nbsp;Kim Baublys ,&nbsp;Harald Hofmann","doi":"10.1016/j.apgeochem.2025.106482","DOIUrl":"10.1016/j.apgeochem.2025.106482","url":null,"abstract":"<div><div>Methane and carbon dioxide are ubiquitous in aquifers and are gaining increased attention through their role in global warming. The stable carbon and hydrogen isotopes of methane and carbon dioxide, δ¹³C–CH₄, δ¹³C–CO₂ and δ²H–CH₄, can inform on the sources of gas in groundwater and determine if the origin is via thermogenic or different biogenic (microbial) processes. This can, for example, inform if there is connectivity between gas reservoirs and overlying aquifers. These stable isotopes are also used in monitoring in a range of settings, for example, during CO₂ geological storage. The pumping of groundwater to the surface results in depressurisation and gas effervescence, therefore the sampling method (i.e. if the sample contacts atmosphere) is known to affect measured dissolved gas concentrations; however, the effect of sample collection on the stable isotopes remains unresolved. Gas stable isotopes can be collected in the field in a range of sample containers, including dissolved gases in exetainer vials or Isoflasks; or free gases in gas bags or cylinders. Aquifer groundwaters, coal seam gas (CSG) production waters, and CSG free gases were collected from a range of bores for δ¹³C–CH₄, δ¹³C–CO_2, and δ²H–CH₄ analysis. Sample pairs of dissolved gases from exetainer vials and Isoflasks were mainly compared and generally had excellent low directional percentage variabilities. A subset of sample pairs from other containers (including free gas in gas cylinders or gas bags) were also compared with consistent stable isotope signatures generally measured. This brings confidence for using different sample containers if needed for different field conditions and situations.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106482"},"PeriodicalIF":3.1,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144502780","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":"The geochemical composition of Wellington soils and other New Zealand urban soils under different land-use","authors":"K.M. Rogers ,&nbsp;R. Morgenstern ,&nbsp;M.S. Rattenbury ,&nbsp;K.P. Norton ,&nbsp;C. Doogue ,&nbsp;M. Kah ,&nbsp;S.A. Sari ,&nbsp;R.E. Turnbull ,&nbsp;A.P. Martin","doi":"10.1016/j.apgeochem.2025.106485","DOIUrl":"10.1016/j.apgeochem.2025.106485","url":null,"abstract":"<div><div>A recent soil geochemical baseline survey of the Wellington urban area analysed samples collected at multiple depths across 151 sites from a mixture of residential, commercial, industrial, pasture, native forest and exotic forest land. The parent material of Wellington soils is mostly chemically invariant, requiring data outliers to be explained by environmental or anthropogenic factors. Notable concentrations above guidance level environmental standards were found in surface (0–2 cm) and shallow (2–20 cm) soils for As, Cd and Pb. The concentration of these heavy metal contaminants in Wellington soils are likely associated with human activities, as the highest concentrations correlate to more densely populated urban areas, particularly where older pre-1960s housing stock exists. This pattern of heavy metal enrichment in New Zealand urban soils relative to regional soils is also observed in comparative urban studies in Auckland and Dunedin cities. Wellington urban soils overall have lower concentrations of Cd and higher concentrations of As, Pb, and Zn compared to Auckland and/or Dunedin. In contrast, Auckland and Dunedin urban soils have a broader enrichment in some heavy metals (including Cr, Cu, and Ni) directly associated with a strong geogenic influence from underlying volcanic geological sources, while Wellington urban soils are influenced by monolithic greywacke. This study also showed that the carbon content of soils in these three centres increases by up to 66 % with increasing latitude due to better C preservation in cooler southern climates. Moreover, urban soils are found to have lower C contents than native, pasture and exotic soils due to more rapid soil turnover rates which leads to increased microbial activity, although this is also dependant on plant type, with C4 grasses commonly found in the warmer and drier climates of Auckland being more recalcitrant in soil than C3 plants. Geochemical studies from across New Zealand show that both urbanisation and underlying geology exert a strong influence on elemental soil concentrations, with the highest heavy metal values commonly associated with cities with the longest history of European settlement. Climate and land use type are also key drivers for elemental retention in shallow soils.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106485"},"PeriodicalIF":3.1,"publicationDate":"2025-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144470563","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":"Spatial distribution, potential sources and geochemical baseline of Fe and potentially toxic elements in stream sediments in Quadrilátero Ferrífero, Brazil","authors":"Lucio Cardoso de Medeiros Filho ,&nbsp;Gabriel Negreiros Salomão ,&nbsp;Roberto Dall’Agnol ,&nbsp;Gabriel Soares de Almeida ,&nbsp;Rafael Tarantino Amarante ,&nbsp;Prafulla Kumar Sahoo ,&nbsp;José Tasso Felix Guimarães ,&nbsp;Emmanoel Vieira da Silva Filho ,&nbsp;Eduardo Duarte Marques ,&nbsp;Lucas Pereira Leão ,&nbsp;Raquel Fernandes Mendonça ,&nbsp;Abraão Gomes Soares Junior","doi":"10.1016/j.apgeochem.2025.106483","DOIUrl":"10.1016/j.apgeochem.2025.106483","url":null,"abstract":"<div><div>This study investigates geochemical baselines and the spatial distribution of potentially toxic elements (PTE) in stream sediments of the Quadrilátero Ferrífero (QF), Brazil—an iron-rich province with complex geology and extensive mining activity. A total of 804 microcatchments were sampled and analyzed for 15 environmentally relevant elements (including Fe, As, Cd, Hg, Ni, and Zn), selected based on their ecological significance, toxicity, and geogenic occurrence in mineralized terrains. Geochemical baselines were calculated using median ±2 × median absolute deviation (mMAD) and Tukey's Inner Fence (TIF), with mMAD providing more conservative and robust thresholds. A compositional data analysis (CoDA) framework was applied using isometric log-ratio (ilr) transformation and robust principal component analysis (RPCA) to explore geochemical-lithological affinities. Results showed that metavolcano-sedimentary sequences, especially from the Rio das Velhas and Minas Supergroups, exhibit elevated concentrations of multiple PTEs, while metabasic and ultrabasic units are enriched in Cr, Ni, and Co. The TTGM unit also showed distinctive enrichment in Ba and Pb. Spatial patterns suggest that lithology is one of the main controls on PTE distribution and represents a valuable tool for interpreting geochemical variation in mineralized regions. These findings offer a solid basis for environmental monitoring and future integration with land use data to support contamination risk assessments and sustainable watershed management in areas such as the QF.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106483"},"PeriodicalIF":3.4,"publicationDate":"2025-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144756867","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":"Characterization of fractured serpentinite at Shulaps, Coquihalla, and Tulameen sites in British Columbia: Implications for carbon storage","authors":"Katrin Steinthorsdottir ,&nbsp;Gregory M. Dipple ,&nbsp;Xueya Lu ,&nbsp;Sandra Ósk Snæbjörnsdóttir ,&nbsp;Randolph J. Enkin","doi":"10.1016/j.apgeochem.2025.106481","DOIUrl":"10.1016/j.apgeochem.2025.106481","url":null,"abstract":"<div><div>This study presents a geological characterization of variably serpentinized harzburgite and dunite of the Shulaps, Coquihalla, and Tulameen sites in southwestern British Columbia. Surface geological data are used to determine the injectivity and reactivity for carbon storage via shallow CO₂ injection and mineralization. Injectivity into a fracture-hosted reservoir was assessed by measuring fracture intensity and connectivity, which were quantified on an outcrop scale and considered together with the physical properties of rock samples collected from the field sites. Pervasively serpentinized harzburgite from Shulaps and Coquihalla are more fractured than partially serpentinized harzburgite and dunite. Additionally, rock mineral content, bulk rock chemical composition and dissolution rates of selected samples were used to assess reactivity. Serpentinized dunite from Tulameen is more reactive than serpentinized harzburgite. The data collected can help assess baseline data, modeling inputs, and well-targeting.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106481"},"PeriodicalIF":3.1,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144480103","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":"The mobility of U(VI) associated with Fe(II)-induced transformation of schwertmannite and its reductive dissolution and re-precipitation in AMD environment","authors":"Chang He ,&nbsp;Yu Ning ,&nbsp;Yilian Li ,&nbsp;Hongyan Guo ,&nbsp;Zhe Yang ,&nbsp;Sen Yang ,&nbsp;Fengcheng Jiang","doi":"10.1016/j.apgeochem.2025.106467","DOIUrl":"10.1016/j.apgeochem.2025.106467","url":null,"abstract":"<div><div>The formation and phase transformation of schwertmannite (Sch) in sulfate-rich AMD systems could significantly affect the migration and transformation of U(VI) via adsorption or co-precipitation. To explore this geochemical process, this study investigated the phase transformation of Sch and re-distribution behavior of U(VI) in simulated anaerobic AMD systems. The results demonstrated that Fe²⁺ had activated the adsorbed U(VI) through facilitating phase transformation. However, following activation by Fe²⁺, the residual U(VI) became more firmly bound to Sch than when extracted by hydrochloric acid, which could be attributed to a variety of mechanisms induced by Fe²⁺, including competitive adsorption on Sch and its reduction, dissolution and re-precipitation. Compared with Fe²⁺, pH plays a more auxiliary and enhanced role in the reduction and phase transformation of Sch. The X-ray photoelectron spectroscopy and XRD results revealed an increase in the pH-enhanced reduction of adsorbed U(VI) and structural Fe(III) by enhancing the adsorption capacity of Fe²⁺, bolstering solid–liquid electron transfer and promoting the reductive activity of the Fe²⁺ complexes formed on the Sch surface, thereby enhancing the reductive dissolution and re-precipitation of Sch coupled with competitive substitution of surface SO₄²⁻ by enriched OH⁻.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106467"},"PeriodicalIF":3.1,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298022","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":"The SIT model parameters for interactions of phosphate ions with Na+ and K+ ions accounting for dimerization of the H2PO4‐ anion","authors":"Andrey V. Plyasunov,&nbsp;Elena V. Cherkasova","doi":"10.1016/j.apgeochem.2025.106477","DOIUrl":"10.1016/j.apgeochem.2025.106477","url":null,"abstract":"<div><div>The SIT model is a simple yet physically sound model for activity coefficients in aqueous solutions, which has only one binary interaction parameter for each pair of cations and anions. It has long been known that the SIT model performs poorly for the thermodynamic activity data for aqueous solutions of <span><math><mrow><mi>N</mi><msub><mtext>aH</mtext><mn>2</mn></msub><mi>P</mi><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span> and <span><math><mrow><mi>K</mi><msub><mi>H</mi><mn>2</mn></msub><mi>P</mi><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span>. However, the previous treatment ignored the dimerization of the <span><math><mrow><msub><mi>H</mi><mn>2</mn></msub><mi>P</mi><msubsup><mi>O</mi><mn>4</mn><mo>‐</mo></msubsup></mrow></math></span> anion with the formation of <span><math><mrow><msub><mi>H</mi><mn>4</mn></msub><msub><mi>P</mi><mn>2</mn></msub><msubsup><mi>O</mi><mn>8</mn><mrow><mn>2</mn><mo>‐</mo></mrow></msubsup></mrow></math></span>, which has been convincingly demonstrated, mainly in Raman experiments. Here we show that explicitly taking into account the dimerization of the <span><math><mrow><msub><mi>H</mi><mn>2</mn></msub><mi>P</mi><msubsup><mi>O</mi><mn>4</mn><mo>‐</mo></msubsup></mrow></math></span> anion allows to reproduce accurately the experimental data on the stoichiometric mean ionic activity coefficients for aqueous <span><math><mrow><mi>N</mi><msub><mtext>aH</mtext><mn>2</mn></msub><mi>P</mi><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span> and <span><math><mrow><mi>K</mi><msub><mi>H</mi><mn>2</mn></msub><mi>P</mi><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span>. The data were processed using relations from the thermodynamics of partially associated electrolytes. An additional source of information were the values of the dissociation constants of phosphoric acid in <span><math><mrow><mtext>NaCl</mtext></mrow></math></span> and <span><math><mrow><mtext>KCl</mtext></mrow></math></span> solutions. In total, we determined 8 SIT parameters for the interactions of <span><math><mrow><msup><mtext>Na</mtext><mo>+</mo></msup></mrow></math></span> and <span><math><mrow><msup><mi>K</mi><mo>+</mo></msup></mrow></math></span> with different phosphate ions at 298.15 K and 0.1 MPa.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106477"},"PeriodicalIF":3.1,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144322515","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":"Examination of Np(V) sorption to montmorillonite as a function of temperature (25–55 °C) and ionic strength","authors":"Fanny Coutelot ,&nbsp;Matthew Riss ,&nbsp;Deborah L. Wang ,&nbsp;Daniel T. Olive ,&nbsp;Andreas Schnurr ,&nbsp;Brian A. Powell","doi":"10.1016/j.apgeochem.2025.106466","DOIUrl":"10.1016/j.apgeochem.2025.106466","url":null,"abstract":"<div><div>Because of the prevalence of clays in rocks, soils, and sediments, and their proposed use in nuclear waste storage sites, clay materials are an important consideration in radionuclide interactions in the environment. This study examined Np(V) sorption to Na-montmorillonite as a function of temperature and ionic strength. Batch sorption experiments were conducted at 25 °C, 35 °C, 45 °C, 55 °C for 0.01, 0.1, and 1.0 M NaCl ionic strengths. The data indicate that Np(V) sorption to montmorillonite at pH values above 6 increases slightly with increasing temperature. The displacement of hydrating waters from the neptunium cation and clay surface may be the driving force behind the increased sorption, which is postulated based on the entropically driven removal of water molecules from the primary hydration sphere to bulk water. A double-layer (DLM) surface complexation model was applied to describe the Np(V) sorption data with activities of the dissolved aqueous species and estimate their associated log K values, allowing for an estimation of the adsorption enthalpy. X-ray absorption spectroscopy (XAS) measurements confirmed one of the essential assumptions for modeling at high ionic strengths: no variation in surface speciation appears between low and high ionic strength samples. XAS analysis confirmed Np(V) remained in the pentavalent oxidation state and indicated similar surface speciation for both low and high ionic strength conditions, with no evidence of Np precipitation. These results provide insights into Np(V) sorption behavior under conditions relevant to nuclear waste repositories, including elevated temperatures and high ionic strengths. The slight increase in sorption with temperature suggests Np(V) mobility may be somewhat reduced in heated repository environments. However, the overall weak sorption indicates Np(V) remains relatively mobile under most conditions studied.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106466"},"PeriodicalIF":3.1,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696609","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":"Lithium resource mapping in Afghanistan's Helmand Basin: A multi-criteria approach of zonation using the Analytic Hierarchy Process","authors":"Antarip Hazarika,&nbsp;Biswajit Thander,&nbsp;Siddhartha Kumar Lahiri","doi":"10.1016/j.apgeochem.2025.106460","DOIUrl":"10.1016/j.apgeochem.2025.106460","url":null,"abstract":"<div><div>The Helmand Basin, which spans southern Afghanistan and parts of Iran and Pakistan, is a hyperarid, endorheic region with a high potential for lithium-brine (Li-brine) deposits. Although lithium is available in nature as a primary source (for instance, granite pegmatite type) and as a secondary source of deposition in salt lakes or palaeo-salars in the subsurface, a generalised methodology for adopting a priority-based lithium exploration policy is still absent. This study, driven by a heuristic approach, specifically explores the Helmand basin's tectonic complexity, as well as its climatic and geological conditions, which make it a promising target for Li-brine exploration. By utilising the Analytic Hierarchy Process (AHP), we systematically identified potential Li-source and accumulation zones by parameterising key factors such as hydrothermal activity, Li-rich lithology, crustal thickness, arid climate, and tectonic subsidence. The spatial zonation model developed in this study predicts areas with varying probabilities for Li-brine systems, highlighting the northeastern basin as the most promising for Li sources. Specific recharge and transport pathways were identified, mapping Li migration from source zones to high-elevation lakes, including Ab-e Istada and Dasht-e Nawar. Additionally, the Godzareh Depression emerged as a significant Li-brine accumulation site, benefiting from regional recharge throughout the entire basin. This study demonstrates the utility of AHP in integrating complex geospatial data for precise Li-brine exploration. The results provide a strategic framework for guiding economically viable lithium resource development, positioning the Helmand Basin as a key contributor to the global Li-brine supply.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106460"},"PeriodicalIF":3.1,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298020","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}