Pub Date : 2025-12-06DOI: 10.1016/j.apgeochem.2025.106649
Dongfang Ke , Weiqiang Feng , Peng Liao , Rong Li , Ruina Xu , Yu-Min Chou , Peixue Jiang
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 (<0.22 %) and purity degradation (<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 (Vmax) 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.
{"title":"Kinetic model reveals microbial-mediated hydrogen consumption and abiotic mineral reactions jointly control hydrogen depletion during geological storage","authors":"Dongfang Ke , Weiqiang Feng , Peng Liao , Rong Li , Ruina Xu , Yu-Min Chou , 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 (<0.22 %) and purity degradation (<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><sub>max</sub>) exceeds 10<sup>−4.5</sup> s<sup>−1</sup>; 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., SO<sub>4</sub><sup>2−</sup>, HCO<sub>3</sub><sup>−</sup>). 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":"2025-12-06","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}
Pub Date : 2025-12-03DOI: 10.1016/j.apgeochem.2025.106648
Erik J.H. Oerter , Miguel Cisneros , Eric Pili , Michael Singleton , Pierre Agrinier , Travis Tenner , Ruth Kips
Determining the origin and history of interdicted nuclear materials is a central challenge in nuclear forensics. The oxygen stable isotope composition of uranium oxide compounds has emerged as a promising forensic signature, attracting increasing attention since the early 2000s. This review examines analytical techniques for measuring oxygen isotope compositions in uranium oxides and evaluates how the nuclear fuel production cycle introduces or modifies these isotopic signatures. The potential for forensic geolocation is explored through workflows that calibrate the relationship between environmental water oxygen isotopes and those found in uranium oxides. Key strengths and limitations of this approach are assessed, including gaps in knowledge related to isotope fractionation during specific stages of the fuel cycle, and processing facility water inputs. The importance of proper sample handling and storage under inert atmospheres, as well as a deeper understanding of both intra-sample oxygen isotope heterogeneity, and hydrous uranium oxide phase formation, is highlighted for improving the reliability of forensic interpretations. The development of uranium oxide standards with well-characterized δ18O values and international collaboration toward consensus on their use are identified as essential steps for advancing the field.
{"title":"Oxygen stable isotopes in the nuclear fuel cycle: Assessment of the potential for determining the fabrication and provenance history of anhydrous and hydrous uranium oxides","authors":"Erik J.H. Oerter , Miguel Cisneros , Eric Pili , Michael Singleton , Pierre Agrinier , Travis Tenner , Ruth Kips","doi":"10.1016/j.apgeochem.2025.106648","DOIUrl":"10.1016/j.apgeochem.2025.106648","url":null,"abstract":"<div><div>Determining the origin and history of interdicted nuclear materials is a central challenge in nuclear forensics. The oxygen stable isotope composition of uranium oxide compounds has emerged as a promising forensic signature, attracting increasing attention since the early 2000s. This review examines analytical techniques for measuring oxygen isotope compositions in uranium oxides and evaluates how the nuclear fuel production cycle introduces or modifies these isotopic signatures. The potential for forensic geolocation is explored through workflows that calibrate the relationship between environmental water oxygen isotopes and those found in uranium oxides. Key strengths and limitations of this approach are assessed, including gaps in knowledge related to isotope fractionation during specific stages of the fuel cycle, and processing facility water inputs. The importance of proper sample handling and storage under inert atmospheres, as well as a deeper understanding of both intra-sample oxygen isotope heterogeneity, and hydrous uranium oxide phase formation, is highlighted for improving the reliability of forensic interpretations. The development of uranium oxide standards with well-characterized δ<sup>18</sup>O values and international collaboration toward consensus on their use are identified as essential steps for advancing the field.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106648"},"PeriodicalIF":3.4,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733228","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}
Pub Date : 2025-12-03DOI: 10.1016/j.apgeochem.2025.106647
Zhenchen Wan , Yuxuan Tan , Yunsong Zheng , Xiuli Li , Songhu Yuan
Dissolved O2 (DO) levels in the shallow subsurface, controlled by both chemical and biological processes, play an important role in contaminant transformation and attenuation. However, methods for tracing chemical and biological DO consumption are not available. Here we show that oxygen isotope enrichment factors (ε) can be used to trace the mechanisms of chemical and biological O2 consumption in the shallow subsurface. In batch solution experiments, the ε values for O2 consumption by dissolved Fe(II), dissolved organic carbon (DOC), and their mixtures at different C/Fe ratios (0.5∼20) were measured to range from -1.74 ‰ to -3.32 ‰. In the oxygenation of reduced clayed sediment suspension, the ε values were relatively small (-6.46 ‰) in the initial 15 h and increased to a large level (-18.14 ‰) afterward; while for the sand sediment suspension, the ε values were always small (ranging from -4.56 ‰ to -4.65 ‰) throughout the duration time of 24 h. Chemical probe and sterilized control experiments proved that the initial stage characterized with small ε values (<-10 ‰) was dominated by chemical O2 consumption and the subsequent stage with large ε values (>-10 ‰) was dominated by biological O2 consumption. As an effective indicator for distinguishing subsurface chemical and biological oxygen consumption pathways, ε will provide a new parameter for exploring carbon and nitrogen cycling and pollution transformation.
{"title":"Tracing chemical and biological O2 consumption in the subsurface by 18O isotope enrichment factors","authors":"Zhenchen Wan , Yuxuan Tan , Yunsong Zheng , Xiuli Li , Songhu Yuan","doi":"10.1016/j.apgeochem.2025.106647","DOIUrl":"10.1016/j.apgeochem.2025.106647","url":null,"abstract":"<div><div>Dissolved O<sub>2</sub> (DO) levels in the shallow subsurface, controlled by both chemical and biological processes, play an important role in contaminant transformation and attenuation. However, methods for tracing chemical and biological DO consumption are not available. Here we show that oxygen isotope enrichment factors (<em>ε</em>) can be used to trace the mechanisms of chemical and biological O<sub>2</sub> consumption in the shallow subsurface. In batch solution experiments, the <em>ε</em> values for O<sub>2</sub> consumption by dissolved Fe(II), dissolved organic carbon (DOC), and their mixtures at different C/Fe ratios (0.5∼20) were measured to range from -1.74 ‰ to -3.32 ‰. In the oxygenation of reduced clayed sediment suspension, the <em>ε</em> values were relatively small (-6.46 ‰) in the initial 15 h and increased to a large level (-18.14 ‰) afterward; while for the sand sediment suspension, the <em>ε</em> values were always small (ranging from -4.56 ‰ to -4.65 ‰) throughout the duration time of 24 h. Chemical probe and sterilized control experiments proved that the initial stage characterized with small <em>ε</em> values (<-10 ‰) was dominated by chemical O<sub>2</sub> consumption and the subsequent stage with large <em>ε</em> values (>-10 ‰) was dominated by biological O<sub>2</sub> consumption. As an effective indicator for distinguishing subsurface chemical and biological oxygen consumption pathways, <em>ε</em> will provide a new parameter for exploring carbon and nitrogen cycling and pollution transformation.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106647"},"PeriodicalIF":3.4,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681777","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}
Pub Date : 2025-11-29DOI: 10.1016/j.apgeochem.2025.106646
Helge C. Moog , Marcus Altmaier , Frank Bok , Vinzenz Brendler , Daniela Freyer , Xavier Gaona , Sven Hagemann , Claudia Joseph , George-Dan Miron , Melanie Pannach , Julia Sohr , Wolfgang Voigt , Marie Voss , Laurin Wissmeier
The Thermodynamic Reference Database (THEREDA) is designed for geochemical calculations in the context of repositories for radioactive waste under high-saline conditions. For this purpose, it adopts the Pitzer ion-interaction approach. THEREDA is currently the only database worldwide that allows comprehensive polythermal calculations (up to at least 100 °C) of the hexary system of the oceanic salts Na-K-Mg-Ca-Cl-SO4-H2O, including acids, bases, and CO2/carbonates. Its validity is documented primarily, yet not exclusively, by application to solubility data. THEREDA's potential to predict the development of the geochemical environment, e.g. in the event of an intrusion of solution, constitutes a prerequisite for the engineering design of a nuclear waste repository with regard to the selection and placement of plug and sealing system components.
The focus of THEREDA lies on the calculation of solubilities of radionuclides (actinides, fission and activation products), chemotoxic and matrix elements e.g., canister materials, and compounds having an impact on the overall geochemical milieu in the near field of a repository under high-saline conditions.
Special features of THEREDA besides its focus on high-saline solutions are procedures for testing prior to any release combined with intercode-comparison, extensive and publicly available validation against published experimental data, and systematic application of a scheme to mark data with regard to quality, reliability, and origin. Traceability of data and validated experimental results to published sources is also emphasised. This documentation is in part realised in ready-to-use parameter files for users, and in part on the website (www.thereda.de). Another feature is the possibility for operation of THEREDA by several institutions in a net-worked manner.
To highlight THEREDA's potential, examples for applications of the database are given. Additionally, ongoing efforts for the further development of THEREDA are described in the outlook at the end of this article.
{"title":"THEREDA: Thermodynamic reference database for geochemical modelling of nuclear waste disposal under saline conditions – Application, overview, and new developments","authors":"Helge C. Moog , Marcus Altmaier , Frank Bok , Vinzenz Brendler , Daniela Freyer , Xavier Gaona , Sven Hagemann , Claudia Joseph , George-Dan Miron , Melanie Pannach , Julia Sohr , Wolfgang Voigt , Marie Voss , Laurin Wissmeier","doi":"10.1016/j.apgeochem.2025.106646","DOIUrl":"10.1016/j.apgeochem.2025.106646","url":null,"abstract":"<div><div>The Thermodynamic Reference Database (THEREDA) is designed for geochemical calculations in the context of repositories for radioactive waste under high-saline conditions. For this purpose, it adopts the Pitzer ion-interaction approach. THEREDA is currently the only database worldwide that allows comprehensive polythermal calculations (up to at least 100 °C) of the hexary system of the oceanic salts Na-K-Mg-Ca-Cl-SO<sub>4</sub>-H<sub>2</sub>O, including acids, bases, and CO<sub>2</sub>/carbonates. Its validity is documented primarily, yet not exclusively, by application to solubility data. THEREDA's potential to predict the development of the geochemical environment, e.g. in the event of an intrusion of solution, constitutes a prerequisite for the engineering design of a nuclear waste repository with regard to the selection and placement of plug and sealing system components.</div><div>The focus of THEREDA lies on the calculation of solubilities of radionuclides (actinides, fission and activation products), chemotoxic and matrix elements e.g., canister materials, and compounds having an impact on the overall geochemical milieu in the near field of a repository under high-saline conditions.</div><div>Special features of THEREDA besides its focus on high-saline solutions are procedures for testing prior to any release combined with intercode-comparison, extensive and publicly available validation against published experimental data, and systematic application of a scheme to mark data with regard to quality, reliability, and origin. Traceability of data and validated experimental results to published sources is also emphasised. This documentation is in part realised in ready-to-use parameter files for users, and in part on the website (<span><span>www.thereda.de</span><svg><path></path></svg></span>). Another feature is the possibility for operation of THEREDA by several institutions in a net-worked manner.</div><div>To highlight THEREDA's potential, examples for applications of the database are given. Additionally, ongoing efforts for the further development of THEREDA are described in the outlook at the end of this article.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106646"},"PeriodicalIF":3.4,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733114","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}
Pub Date : 2025-11-26DOI: 10.1016/j.apgeochem.2025.106637
José Ignacio Barquero , Jesús Peco , Jaime Villena , Juan A. Campos , José A. Amorós , José María Esbrí , Francisco J. García-Navarro , Marta María Moreno , Pablo Higueras
Background and aims
Abandoned mining areas represent critical environmental pollution hotspots due to the persistence of waste materials enriched in potentially toxic elements (PTEs). This study evaluates the transfer of PTEs from contaminated soils to six plant species in the vicinity of the San Quintín Pb–Zn mine (Ciudad Real, Spain), a site impacted by over a century of mining activity.
Methods
The studied species include the tree Quercus ilex, the shrubs Retama sphaerocarpa and Scrophularia canina, and the annual herbaceous species Spergularia rubra, Rumex bucephalophorus, and Hirschfeldia incana. Soil and plant tissue samples were analysed using X-ray fluorescence and atomic absorption spectrometry to determine concentrations of Zn, Pb, Hg, Cu, and other PTEs.
Results
Results revealed a high heterogeneity in the bioaccumulation of elements such as Zn, Pb, Hg, and Cu among the studied species, with Spergularia rubra and Rumex bucephalophorus emerging as effective bioindicators of soil contamination. The presence of acid mine drainage (AMD) significantly reduced soil pH (average ≈ 5.7), enhancing PTE solubility (e.g., Zn2+ release) and facilitating their uptake by plants (Bravo et al., 2017). Specific correlations between soil and plant concentrations were identified, and atmospheric uptake was found to significantly influence Hg accumulation in plant tissues.
Conclusions
This study revealed high PTE contamination and spatial heterogeneity in the San Quintín mining area, with concentration ranges (mg kg−1) of 13–806 for Sb, 70–57,270 for Pb, 68–48,460 for Zn, 18–1680 for Cu, and 3–1920 for Hg, as the most significant elements. Species such as Spergularia rubra and Rumex bucephalophorus exhibited strong metal accumulation, with average concentrations (mg kg−1) of 1460 and 552 for Pb, 1232 and 927 for Zn, 36 and 22 for Cu, and 28 and 9 for Hg, respectively, and the average Pb BAC for S. rubra of 0.15, significantly higher than that of other species. These results indicate the potential of these two species for bioindication and phytoremediation. Furthermore, Hg accumulation in S. rubra follows a logarithmic trend (R2 = 0.98), confirming that atmospheric uptake by leaves supposes an important contribution to bioaccumulation of the element in plants. These results indicate the potential of both species for bioindication and phytoremediation. Mercury uptake was influenced not only by the edaphic compartment but also by atmospheric deposition and plant foliar traits. Overall, these findings provide a better understanding of PTE dynamics within the soil–plant system and support phytoremediation strategies in degraded mining environments.
{"title":"Transference of potentially toxic elements from soils to plants in a derelict Pb–Zn mining area (San Quintín mine, South-Central Spain)","authors":"José Ignacio Barquero , Jesús Peco , Jaime Villena , Juan A. Campos , José A. Amorós , José María Esbrí , Francisco J. García-Navarro , Marta María Moreno , Pablo Higueras","doi":"10.1016/j.apgeochem.2025.106637","DOIUrl":"10.1016/j.apgeochem.2025.106637","url":null,"abstract":"<div><h3>Background and aims</h3><div>Abandoned mining areas represent critical environmental pollution hotspots due to the persistence of waste materials enriched in potentially toxic elements (PTEs). This study evaluates the transfer of PTEs from contaminated soils to six plant species in the vicinity of the San Quintín Pb–Zn mine (Ciudad Real, Spain), a site impacted by over a century of mining activity.</div></div><div><h3>Methods</h3><div>The studied species include the tree <em>Quercus ilex</em>, the shrubs <em>Retama sphaerocarpa</em> and <em>Scrophularia canina</em>, and the annual herbaceous species <em>Spergularia rubra</em>, <em>Rumex bucephalophorus</em>, and <em>Hirschfeldia incana</em>. Soil and plant tissue samples were analysed using X-ray fluorescence and atomic absorption spectrometry to determine concentrations of Zn, Pb, Hg, Cu, and other PTEs.</div></div><div><h3>Results</h3><div>Results revealed a high heterogeneity in the bioaccumulation of elements such as Zn, Pb, Hg, and Cu among the studied species, with <em>Spergularia rubra</em> and <em>Rumex bucephalophorus</em> emerging as effective bioindicators of soil contamination. The presence of acid mine drainage (AMD) significantly reduced soil pH (average ≈ 5.7), enhancing PTE solubility (e.g., Zn<sup>2+</sup> release) and facilitating their uptake by plants (Bravo et al., 2017). Specific correlations between soil and plant concentrations were identified, and atmospheric uptake was found to significantly influence Hg accumulation in plant tissues.</div></div><div><h3>Conclusions</h3><div>This study revealed high PTE contamination and spatial heterogeneity in the San Quintín mining area, with concentration ranges (mg kg<sup>−1</sup>) of 13–806 for Sb, 70–57,270 for Pb, 68–48,460 for Zn, 18–1680 for Cu, and 3–1920 for Hg, as the most significant elements. Species such as <em>Spergularia rubra</em> and <em>Rumex bucephalophorus</em> exhibited strong metal accumulation, with average concentrations (mg kg<sup>−1</sup>) of 1460 and 552 for Pb, 1232 and 927 for Zn, 36 and 22 for Cu, and 28 and 9 for Hg, respectively, and the average Pb BAC for <em>S. rubra</em> of 0.15, significantly higher than that of other species. These results indicate the potential of these two species for bioindication and phytoremediation. Furthermore, Hg accumulation in <em>S. rubra</em> follows a logarithmic trend (R<sup>2</sup> = 0.98), confirming that atmospheric uptake by leaves supposes an important contribution to bioaccumulation of the element in plants. These results indicate the potential of both species for bioindication and phytoremediation. Mercury uptake was influenced not only by the edaphic compartment but also by atmospheric deposition and plant foliar traits. Overall, these findings provide a better understanding of PTE dynamics within the soil–plant system and support phytoremediation strategies in degraded mining environments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106637"},"PeriodicalIF":3.4,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681776","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}
Pub Date : 2025-11-26DOI: 10.1016/j.apgeochem.2025.106639
George D. Kamenov , Sean Scott
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.
{"title":"New insights on the Pb isotopic compositions of drinking water lead pipes in the United States","authors":"George D. Kamenov , 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":"2025-11-26","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}
Pub Date : 2025-11-24DOI: 10.1016/j.apgeochem.2025.106638
Wei Zhu , Wei Liu , Na Xu , Robert B. Finkelman
Critical metals such as rare earth elements and yttrium (REY), lithium, gallium, and germanium are essential to modern technologies, but face increasing supply uncertainties. Numerous studies have shown that coal is a promising alternative source for these critical metals. Understanding modes of occurrence of these elements is critical for efficient recovery from coal and its by-products. Traditional statistical analyses, performed on bulk mine datasets, overlook stratigraphic variability, limiting insight into elemental associations. To address this limitation, a sliding-window correlation analysis combined with stratigraphically-constrained Synthetic Minority Over-Sampling Technique was applied to investigate the modes of occurrence of critical elements in coal from the Guanbanwusu mine, Inner Mongolia, China, with specific consideration of vertical stratigraphy. The results reveal significant vertical heterogeneity in modes of occurrence of elements. Lithium exhibits strong correlations with kaolinite and chlorite across most coal benches but shows localized associations with inertinite in the lower part (benches G18-G12 and G8-G1). Gallium and germanium are primarily hosted in goyazite, with variable associations with boehmite, chlorite, and kaolinite. Rare earth elements and yttrium predominantly occur in goyazite, with affinity varying vertically: in upper benches, goyazite shows a stronger affinity for light REY, whereas in lower benches, it is enriched in both light REY and middle REY. In contrast, inertinite exhibits an opposite REY affinity compared to goyazite and chlorite. These trends demonstrate that the modes of occurrence of critical elements are not uniform throughout coal benches but are influenced by localized geochemical conditions and mineralogical variations.
{"title":"Modes of occurrence of critical elements in coals from the Guanbanwusu mine, Inner Mongolia, China: A novel stratigraphy-constrained sliding-window correlation approach","authors":"Wei Zhu , Wei Liu , Na Xu , Robert B. Finkelman","doi":"10.1016/j.apgeochem.2025.106638","DOIUrl":"10.1016/j.apgeochem.2025.106638","url":null,"abstract":"<div><div>Critical metals such as rare earth elements and yttrium (REY), lithium, gallium, and germanium are essential to modern technologies, but face increasing supply uncertainties. Numerous studies have shown that coal is a promising alternative source for these critical metals. Understanding modes of occurrence of these elements is critical for efficient recovery from coal and its by-products. Traditional statistical analyses, performed on bulk mine datasets, overlook stratigraphic variability, limiting insight into elemental associations. To address this limitation, a sliding-window correlation analysis combined with stratigraphically-constrained Synthetic Minority Over-Sampling Technique was applied to investigate the modes of occurrence of critical elements in coal from the Guanbanwusu mine, Inner Mongolia, China, with specific consideration of vertical stratigraphy. The results reveal significant vertical heterogeneity in modes of occurrence of elements. Lithium exhibits strong correlations with kaolinite and chlorite across most coal benches but shows localized associations with inertinite in the lower part (benches G18-G12 and G8-G1). Gallium and germanium are primarily hosted in goyazite, with variable associations with boehmite, chlorite, and kaolinite. Rare earth elements and yttrium predominantly occur in goyazite, with affinity varying vertically: in upper benches, goyazite shows a stronger affinity for light REY, whereas in lower benches, it is enriched in both light REY and middle REY. In contrast, inertinite exhibits an opposite REY affinity compared to goyazite and chlorite. These trends demonstrate that the modes of occurrence of critical elements are not uniform throughout coal benches but are influenced by localized geochemical conditions and mineralogical variations.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106638"},"PeriodicalIF":3.4,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616824","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}
Pub Date : 2025-11-20DOI: 10.1016/j.apgeochem.2025.106633
Christiane Nagel, Harald Neidhardt, Yvonne Oelmann
Hydrological dynamics in drainage ditch sediments may impact phosphorus (P) retention and its potential (re-)release to connected waters. We aimed at understanding the fate of P in drainage ditch sediments under dynamic environmental conditions (i.e., drying-rewetting cycles) by examining P pool transformations through an isotopic labelling and incubation experiment. Fresh sediment samples were labeled with 18O-enriched inorganic P (Pi), followed by a 24-week incubation under different environmental conditions. The sediment material was incubated at three different hydrological regimes, short-pulsed logged (weekly cycles drying-rewetting), long-pulsed logged (biweekly cycles drying-rewetting), and permanently water-logged (consistently water saturated), and two different temperatures (20 °C and 5 °C). Samples were taken at specific times (24 h after labelling, early phase, intermediate phase, late phase). A five-step sequential extraction scheme was combined with δ18O analysis of Pi (δ18OPi) to follow changes in the operationally defined P pools. First, few P pools showed significant changes, but time-resolved results revealed a dynamic interplay between redox conditions, microbial activity and P dynamics. A subsequent decline in microbial P concentrations along with decreasing alkalinity suggested cell death and reduced microbial activity, likely caused by hydrological stress. However, extracellular acid phosphatase activity remained stable. This suggests that while microbial populations were affected, their enzymatic functions persisted, revealing microbial dynamics and stress responses under drying-rewetting conditions. The δ18OPi values in surface-adsorbed pools retained traces of the original Pi label after 24 weeks, allowing tracking of long-term P transformations and distinguishing biological and geochemical reactions. Our results further reflected dynamic transformations of Pi into organic P and vice-versa, which was largely influenced by the hydrological regime and raised the re-mobilization potential of Pi in the long term. This relationship should be integrated into management strategies aimed at mitigating P losses from agricultural catchments, particularly under changing climatic conditions. Future studies should consider pronounced dynamics within P pools that can only be observed through close temporal monitoring, which may not be evident in simple before-and-after comparisons.
{"title":"Dynamics of phosphorus pools in drainage ditch sediments within an agricultural catchment","authors":"Christiane Nagel, Harald Neidhardt, Yvonne Oelmann","doi":"10.1016/j.apgeochem.2025.106633","DOIUrl":"10.1016/j.apgeochem.2025.106633","url":null,"abstract":"<div><div>Hydrological dynamics in drainage ditch sediments may impact phosphorus (P) retention and its potential (re-)release to connected waters. We aimed at understanding the fate of P in drainage ditch sediments under dynamic environmental conditions (i.e., drying-rewetting cycles) by examining P pool transformations through an isotopic labelling and incubation experiment. Fresh sediment samples were labeled with <sup>18</sup>O-enriched inorganic P (P<sub>i</sub>), followed by a 24-week incubation under different environmental conditions. The sediment material was incubated at three different hydrological regimes, short-pulsed logged (weekly cycles drying-rewetting), long-pulsed logged (biweekly cycles drying-rewetting), and permanently water-logged (consistently water saturated), and two different temperatures (20 °C and 5 °C). Samples were taken at specific times (24 h after labelling, early phase, intermediate phase, late phase). A five-step sequential extraction scheme was combined with δ<sup>18</sup>O analysis of P<sub>i</sub> (δ<sup>18</sup>OP<sub>i</sub>) to follow changes in the operationally defined P pools. First, few P pools showed significant changes, but time-resolved results revealed a dynamic interplay between redox conditions, microbial activity and P dynamics. A subsequent decline in microbial P concentrations along with decreasing alkalinity suggested cell death and reduced microbial activity, likely caused by hydrological stress. However, extracellular acid phosphatase activity remained stable. This suggests that while microbial populations were affected, their enzymatic functions persisted, revealing microbial dynamics and stress responses under drying-rewetting conditions. The δ<sup>18</sup>O<sub>Pi</sub> values in surface-adsorbed pools retained traces of the original P<sub>i</sub> label after 24 weeks, allowing tracking of long-term P transformations and distinguishing biological and geochemical reactions. Our results further reflected dynamic transformations of P<sub>i</sub> into organic P and vice-versa, which was largely influenced by the hydrological regime and raised the re-mobilization potential of P<sub>i</sub> in the long term. This relationship should be integrated into management strategies aimed at mitigating P losses from agricultural catchments, particularly under changing climatic conditions. Future studies should consider pronounced dynamics within P pools that can only be observed through close temporal monitoring, which may not be evident in simple before-and-after comparisons.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106633"},"PeriodicalIF":3.4,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570968","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}
Pub Date : 2025-11-20DOI: 10.1016/j.apgeochem.2025.106636
Amidu A. Makwinja , Frances Chikanda , George J. Maneya , Ryosuke Kikuchi , Walubita Mufalo , Akizumi Ishida , Tsubasa Otake
Coal mining can have significant environmental impacts caused by acid mine drainage (AMD). To further our understanding of the environmental impacts of coal mining, a study was conducted in the Livingstonia Coalfield at the Kaziwiziwi and Mchenga coal mines in Malawi. Mine drainage, river water, and rock samples were analyzed to determine their geochemical characteristics and assess potential environmental impacts. Results of onsite measurements and chemical analyses showed that mine drainage at both sites is moderately acidic to neutral (pH = 4.46–7.02) with Fe2+ and SO42− concentrations of 0.30–3.75 and 92.7–593 ppm, respectively. The presence of Fe and SO4 ions is indicative of FeS2 oxidation, which is responsible for AMD. At Kaziwiziwi, AMD was identified at the tailings pond, whereas at Mchenga it occurs in an abandoned underground mine. The underground drainage from the Kaziwiziwi active mine has high concentrations of Ca2+, Mg2+, and HCO3−, indicating the natural neutralization of AMD by mixing with alkaline groundwater. River water has a circumneutral pH and low trace element concentrations (<1 ppm), suggesting minimal AMD. However, the rock samples, particularly mudstone, have acid-generating potential and are a long-term AMD risk. Stable S isotopic analysis indicates that sulfate ions in the AMD are derived from the mudstone, suggesting this rock type is a major source of AMD. Geochemical mixing modeling predicts that fluctuations in river water pH and increased concentrations of dissolved metals (e.g., Mn) will occur when mixed with AMD, thereby highlighting the need for monitoring and mitigation strategies.
{"title":"Geochemical characterization and potential impact of coal mine drainage on river water quality at selected coal mines in the Livingstonia Coalfield, Malawi","authors":"Amidu A. Makwinja , Frances Chikanda , George J. Maneya , Ryosuke Kikuchi , Walubita Mufalo , Akizumi Ishida , Tsubasa Otake","doi":"10.1016/j.apgeochem.2025.106636","DOIUrl":"10.1016/j.apgeochem.2025.106636","url":null,"abstract":"<div><div>Coal mining can have significant environmental impacts caused by acid mine drainage (AMD). To further our understanding of the environmental impacts of coal mining, a study was conducted in the Livingstonia Coalfield at the Kaziwiziwi and Mchenga coal mines in Malawi. Mine drainage, river water, and rock samples were analyzed to determine their geochemical characteristics and assess potential environmental impacts. Results of onsite measurements and chemical analyses showed that mine drainage at both sites is moderately acidic to neutral (pH = 4.46–7.02) with Fe<sup>2+</sup> and SO<sub>4</sub><sup>2−</sup> concentrations of 0.30–3.75 and 92.7–593 ppm, respectively. The presence of Fe and SO<sub>4</sub> ions is indicative of FeS<sub>2</sub> oxidation, which is responsible for AMD. At Kaziwiziwi, AMD was identified at the tailings pond, whereas at Mchenga it occurs in an abandoned underground mine. The underground drainage from the Kaziwiziwi active mine has high concentrations of Ca<sup>2+</sup>, Mg<sup>2+</sup>, and HCO<sub>3</sub><sup>−</sup>, indicating the natural neutralization of AMD by mixing with alkaline groundwater. River water has a circumneutral pH and low trace element concentrations (<1 ppm), suggesting minimal AMD. However, the rock samples, particularly mudstone, have acid-generating potential and are a long-term AMD risk. Stable S isotopic analysis indicates that sulfate ions in the AMD are derived from the mudstone, suggesting this rock type is a major source of AMD. Geochemical mixing modeling predicts that fluctuations in river water pH and increased concentrations of dissolved metals (e.g., Mn) will occur when mixed with AMD, thereby highlighting the need for monitoring and mitigation strategies.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106636"},"PeriodicalIF":3.4,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616755","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}
Pub Date : 2025-11-19DOI: 10.1016/j.apgeochem.2025.106634
Jiaxin Huang , Shengchao Xu , Ningqiang Liu , Taotao Yan , Qingjie Gong
Traditional assessments of heavy metal pollution in soils are often carried out on pollution indices and national standards. However, these methods focus on only elemental concentrations, without considering the relative relationship among elements. Here, we propose a geochemical gene of pollution risk (PRG01) and its risk similarity (RRisk), which are based on the relative relationship between concentrations of heavy metals (Hg, Pb, Cd, Cr, and As) and their contrast elements (Ti, La, Zr, Th, U, and Nb). Through risk similarity, the pollution risk of heavy metals of samples can be classified into six levels, including the safety level (RRisk<20 %) and the risk level 1 to 5 (corresponding RRisk values range from 20 % to 100 %). The geochemical gene of PRG01 and its risk similarity were applied in the Dashanbao area of Yunnan province of China and compared with the national standard GB15618-2018 on the pollution risk assessment of heavy metals in agricultural soils. The results indicate that samples with RRisk<20 % (or in safety level) belong to the non-intervention level (background or screening levels), while samples with RRisk≥40 % are at the non-background level (screening or intervention levels). Therefore, the PRG01 technique can be used as a novel approach and its risk similarity can be viewed as an integrated index for assessing the pollution risk of heavy metals (i.e., Hg, Pb, Cd, Cr, and As) in agricultural soils. The assessment index of risk similarity of PRG01 can not only circumvent the limitation of a one-size-fits-all approach but also compensate for the limitation of GB15618-2018 in assessing soil samples when agricultural land use type and pH data are missing.
{"title":"A geochemical gene of pollution risk (PRG01) for assessing heavy metal pollution based on the relative relationship between elements","authors":"Jiaxin Huang , Shengchao Xu , Ningqiang Liu , Taotao Yan , Qingjie Gong","doi":"10.1016/j.apgeochem.2025.106634","DOIUrl":"10.1016/j.apgeochem.2025.106634","url":null,"abstract":"<div><div>Traditional assessments of heavy metal pollution in soils are often carried out on pollution indices and national standards. However, these methods focus on only elemental concentrations, without considering the relative relationship among elements. Here, we propose a geochemical gene of pollution risk (PRG01) and its risk similarity (<em>R</em><sub>Risk</sub>), which are based on the relative relationship between concentrations of heavy metals (Hg, Pb, Cd, Cr, and As) and their contrast elements (Ti, La, Zr, Th, U, and Nb). Through risk similarity, the pollution risk of heavy metals of samples can be classified into six levels, including the safety level (<em>R</em><sub>Risk</sub><20 %) and the risk level 1 to 5 (corresponding <em>R</em><sub>Risk</sub> values range from 20 % to 100 %). The geochemical gene of PRG01 and its risk similarity were applied in the Dashanbao area of Yunnan province of China and compared with the national standard GB15618-2018 on the pollution risk assessment of heavy metals in agricultural soils. The results indicate that samples with <em>R</em><sub>Risk</sub><20 % (or in safety level) belong to the non-intervention level (background or screening levels), while samples with <em>R</em><sub>Risk</sub>≥40 % are at the non-background level (screening or intervention levels). Therefore, the PRG01 technique can be used as a novel approach and its risk similarity can be viewed as an integrated index for assessing the pollution risk of heavy metals (i.e., Hg, Pb, Cd, Cr, and As) in agricultural soils. The assessment index of risk similarity of PRG01 can not only circumvent the limitation of a one-size-fits-all approach but also compensate for the limitation of GB15618-2018 in assessing soil samples when agricultural land use type and pH data are missing.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106634"},"PeriodicalIF":3.4,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577394","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}
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