Pub Date : 2026-02-01Epub Date: 2026-01-17DOI: 10.1016/j.apgeochem.2026.106705
Leire Coloma, Iratxe Población, Julene Aramendia, Fernando Alberquilla, Jennifer Huidobro, Gorka Arana, Juan Manuel Madariaga
The study of meteorites is important for planetary sciences because, among other things, it can provide information about the geochemical composition of their celestial body of origin. Often, subsample preparation is required to investigate the internal regions of these meteorites. However, during this process, the use of various tools and reagents can introduce contaminants, which are not always fully removable. As a result, exogenous substances may be detected during subsequent geochemical characterization analyses. To prevent the problems that may arise from this issue, this study analyzes multiple Martian meteorites with the aim of identifying contaminants introduced during sample preparation processes. Raman spectroscopy, one of the techniques used for extraterrestrial sample analysis, was employed to detect these residues. Establishing a robust subsample preparation protocol is essential not only for future sample return missions, where the ability to prepare uncontaminated subsamples upon arrival on Earth will be critical for accurate scientific investigations, but also for the handling of any type of meteorite.
{"title":"Analysing the sample preparation process in meteorites and its impact on the pretreatment of returned samples to Earth","authors":"Leire Coloma, Iratxe Población, Julene Aramendia, Fernando Alberquilla, Jennifer Huidobro, Gorka Arana, Juan Manuel Madariaga","doi":"10.1016/j.apgeochem.2026.106705","DOIUrl":"10.1016/j.apgeochem.2026.106705","url":null,"abstract":"<div><div>The study of meteorites is important for planetary sciences because, among other things, it can provide information about the geochemical composition of their celestial body of origin. Often, subsample preparation is required to investigate the internal regions of these meteorites. However, during this process, the use of various tools and reagents can introduce contaminants, which are not always fully removable. As a result, exogenous substances may be detected during subsequent geochemical characterization analyses. To prevent the problems that may arise from this issue, this study analyzes multiple Martian meteorites with the aim of identifying contaminants introduced during sample preparation processes. Raman spectroscopy, one of the techniques used for extraterrestrial sample analysis, was employed to detect these residues. Establishing a robust subsample preparation protocol is essential not only for future sample return missions, where the ability to prepare uncontaminated subsamples upon arrival on Earth will be critical for accurate scientific investigations, but also for the handling of any type of meteorite.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106705"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974369","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 : 2026-02-01Epub Date: 2026-01-05DOI: 10.1016/j.apgeochem.2026.106678
Fan Xia , Guanxia Cai , Min Zhao , Haibo He , Roohollah Noori , Qian Bao , Bo Chen , Yongqiang Zhou
Carbon sequestration and stabilization and their regulatory mechanisms are key issues in studies of inland water carbon cycles, especially in karst areas. Biological carbon pump transforms the timescales for carbon storage from short to long durations through photosynthesis. However, carbon sequestration is not equal to carbon storage. The research on refractory dissolved organic matter (RDOM) in inland water bodies has not been widely conducted. Here, the formation mechanism, environmental factors, temporal and spatial patterns and carbon sink effect of RDOM are discussed. Our review indicates that dissolved inorganic carbon (DIC) and calcium in the water are important factors affecting the composition of DOM, and they also have an indirect impact on the chemical and biological community structure, regulating the strength of the biological carbon pump (BCP) and microbial carbon pump (MCP). We also estimated the production rate of autochthonous RDOM in karst water bodies to be varied from 0.92 to 23.00 mg m−2∙d−1, which is greater than that in marine ecosystems (i.e., 1.55 mg m−2∙d−1 in the South China Sea). It indicates that karst surface water, which is rich in DIC, is conducive to the accumulation and preservation of DOM. The research provides a new perspective for understanding the role of karst water in the global carbon cycle and emphasizes the importance of microorganisms in carbon storage in inland water bodies.
{"title":"The mechanisms and advances in the significant carbon sequestration potential of karst water","authors":"Fan Xia , Guanxia Cai , Min Zhao , Haibo He , Roohollah Noori , Qian Bao , Bo Chen , Yongqiang Zhou","doi":"10.1016/j.apgeochem.2026.106678","DOIUrl":"10.1016/j.apgeochem.2026.106678","url":null,"abstract":"<div><div>Carbon sequestration and stabilization and their regulatory mechanisms are key issues in studies of inland water carbon cycles, especially in karst areas. Biological carbon pump transforms the timescales for carbon storage from short to long durations through photosynthesis. However, carbon sequestration is not equal to carbon storage. The research on refractory dissolved organic matter (RDOM) in inland water bodies has not been widely conducted. Here, the formation mechanism, environmental factors, temporal and spatial patterns and carbon sink effect of RDOM are discussed. Our review indicates that dissolved inorganic carbon (DIC) and calcium in the water are important factors affecting the composition of DOM, and they also have an indirect impact on the chemical and biological community structure, regulating the strength of the biological carbon pump (BCP) and microbial carbon pump (MCP). We also estimated the production rate of autochthonous RDOM in karst water bodies to be varied from 0.92 to 23.00 mg m<sup>−2</sup>∙d<sup>−1</sup>, which is greater than that in marine ecosystems (<em>i.e.</em>, 1.55 mg m<sup>−2</sup>∙d<sup>−1</sup> in the South China Sea). It indicates that karst surface water, which is rich in DIC, is conducive to the accumulation and preservation of DOM. The research provides a new perspective for understanding the role of karst water in the global carbon cycle and emphasizes the importance of microorganisms in carbon storage in inland water bodies.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106678"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974772","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 : 2026-01-01Epub Date: 2026-01-03DOI: 10.1016/j.apgeochem.2026.106677
Chris Ingles , John Mavrogenes , Yue Wang , Maria Cherdantseva , David Saxey , Denis Fougerouse
Biogenic ore formation has long required clarification of depositional mechanisms and textural characteristics such as carbonate dissolution and ‘snow on the roof’. This research explored evidence for microbial sulfate reduction and biogenic mineralisation associated with sulfide ore deposits, using sphalerite from eight locations. Sulfur isotopic and microtextural analyses were conducted on sphalerites from Navan (Ireland), Wiesloch (Germany), Broken Hill supergene, Century and Cadjebut (Australia), Pomorzany (Poland), Balmat (USA) and Geco (Canada), using Sensitive High-Resolution Ion Microprobe, X-ray Fluorescence Microscopy, fluorination, cathodoluminescence, and atom probe tomography. Results correlated microbial sulfate reduction to stromatolitic zonation accompanied by strongly negative δ34S (−10 to −40) and δ33S (−5 to −20). Mississippi Valley-type sphalerites were classified as either MVTa (abiotic) or MVTb (biotic). The colloform banding suggest cyclic ore deposition, which led to the construction of pH dependent precipitation pathways that begin with acidic fluids and evolve into alkaline conditions with ongoing microbial activity. While sulfate reducing bacteria are the most likely organisms associated with sulfide mineralisation, syntrophic microbial communities are also suggested as avenues to process organic compounds such as hydrocarbons and aid sulfate reduction. The distinct isotopic signatures indicate that sphalerite from Navan, Wiesloch and the supergene Broken Hill ores formed from biogenic sulfate reduction. Rayleigh-type closed system isotopic fractionation was identified in abiotic sphalerite from Pomorzany and mass-independent fractionation (resemblant of pre-Great Oxidation Event conditions) in sphalerite from Geco.
生物成因矿长期以来一直需要澄清沉积机制和结构特征，如碳酸盐溶解和“屋顶上的雪”。本研究利用八个地点的闪锌矿，探索了与硫化物矿床相关的微生物硫酸盐还原和生物矿化的证据。采用高分辨率离子探针、x射线荧光显微镜、氟化、阴极发光和原子探针层析技术，对来自爱尔兰Navan、德国Wiesloch、Broken Hill表基因、澳大利亚Century and Cadjebut、波兰Pomorzany、美国Balmat和加拿大Geco等地的闪锌矿进行了硫同位素和微结构分析。结果表明，微生物硫酸盐还原与叠层石带相关，δ34S（−10 ~−40）和δ33S（−5 ~−20）呈强烈负变化。密西西比河谷型闪锌矿分为MVTa（非生物）型和MVTb（生物）型。胶状带表明了循环的矿石沉积，这导致了pH依赖性降水路径的构建，从酸性流体开始，并在微生物活动持续的情况下演变成碱性条件。虽然硫酸盐还原细菌最有可能与硫化物矿化有关，但共生微生物群落也被认为是处理有机化合物（如碳氢化合物）和帮助硫酸盐还原的途径。不同的同位素特征表明，纳万、威斯洛克和表生破碎山的闪锌矿是由生物硫酸盐还原形成的。波莫札尼的非生物闪锌矿中发现了瑞利型封闭体系同位素分馏，Geco闪锌矿中发现了类似于大氧化事件前条件的非质量分馏。
{"title":"Biogenic sphalerite signatures and pH-dependent precipitation pathways","authors":"Chris Ingles , John Mavrogenes , Yue Wang , Maria Cherdantseva , David Saxey , Denis Fougerouse","doi":"10.1016/j.apgeochem.2026.106677","DOIUrl":"10.1016/j.apgeochem.2026.106677","url":null,"abstract":"<div><div>Biogenic ore formation has long required clarification of depositional mechanisms and textural characteristics such as carbonate dissolution and ‘snow on the roof’. This research explored evidence for microbial sulfate reduction and biogenic mineralisation associated with sulfide ore deposits, using sphalerite from eight locations. Sulfur isotopic and microtextural analyses were conducted on sphalerites from Navan (Ireland), Wiesloch (Germany), Broken Hill supergene, Century and Cadjebut (Australia), Pomorzany (Poland), Balmat (USA) and Geco (Canada), using Sensitive High-Resolution Ion Microprobe, X-ray Fluorescence Microscopy, fluorination, cathodoluminescence, and atom probe tomography. Results correlated microbial sulfate reduction to stromatolitic zonation accompanied by strongly negative δ<sup>34</sup>S (−10 to −40) and δ<sup>33</sup>S (−5 to −20). Mississippi Valley-type sphalerites were classified as either MVTa (abiotic) or MVTb (biotic). The colloform banding suggest cyclic ore deposition, which led to the construction of pH dependent precipitation pathways that begin with acidic fluids and evolve into alkaline conditions with ongoing microbial activity. While sulfate reducing bacteria are the most likely organisms associated with sulfide mineralisation, syntrophic microbial communities are also suggested as avenues to process organic compounds such as hydrocarbons and aid sulfate reduction. The distinct isotopic signatures indicate that sphalerite from Navan, Wiesloch and the supergene Broken Hill ores formed from biogenic sulfate reduction. Rayleigh-type closed system isotopic fractionation was identified in abiotic sphalerite from Pomorzany and mass-independent fractionation (resemblant of pre-Great Oxidation Event conditions) in sphalerite from Geco.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106677"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922382","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 : 2026-01-01Epub Date: 2025-12-31DOI: 10.1016/j.apgeochem.2025.106671
Debbrota Mallick , Xiangli Wang , Marzia Miletto , Jeffrey W. Krause , Daniel C. Ohnemus , Noah J. Planavsky , George W. Luther , Timothy W. Lyons , Bradley M. Tebo
The chromium (Cr) stable isotope compositions of sedimentary rocks have been used to track the evolution of oxygen levels in Earth's ocean-atmosphere system. However, the Cr isotope fractionation during transfer of dissolved Cr to sediments is still unclear. The Chesapeake Bay is a seasonally redox-stratified estuary (oxic surface water overlying euxinic, or sulfide-bearing, deep water) and thus provides a good opportunity to investigate Cr isotope fractionation in euxinic systems. Here we report total dissolved Cr concentrations and stable isotope compositions (δ53Cr) of a water column in this estuary. As salinity increases from 7.51 in the oxic surface water to 19.22 in the euxinic deep water, total dissolved Cr concentration decreases from 1.21 nmol kg−1 to 0.51 nmol kg−1, while δ53Cr decreases from 0.60 ‰ to −0.41 ‰. Explaining these data requires partial reduction of Cr(VI) to Cr(III) followed by incomplete scavenging of Cr(III) from solution, which leads to isotope fractionation during removal of Cr from seawater to anoxic sediments. An extensive compilation of redox-stratified systems suggests that Cr isotope fractionation during removal from anoxic water column is a common phenomenon. This has major implications for using the δ53Cr of anoxic sediments to reconstruct paleo-seawater δ53Cr values. Correcting for such fractionation will require better understanding of its governing factors, which would need more data for sediment trap, porewater, and redox-specific water column samples from anoxic settings.
沉积岩的铬（Cr）稳定同位素组成已被用于追踪地球海洋-大气系统中氧水平的演变。然而，溶解Cr向沉积物转移过程中的Cr同位素分馏仍不清楚。切萨皮克湾是一个季节性氧化还原层状河口（含氧地表水覆盖含氧水体或含硫化物的深水），因此为研究含氧水体中Cr同位素分异提供了良好的机会。本文报道了该河口水柱的总溶解Cr浓度和稳定同位素组成（δ53Cr）。随着盐度从含氧地表水的7.51上升到含氧深水的19.22，总溶解Cr浓度从1.21 nmol kg - 1下降到0.51 nmol kg - 1， δ53Cr从0.60‰下降到- 0.41‰。解释这些数据需要将Cr（VI）部分还原为Cr(III)，然后从溶液中不完全清除Cr(III)，这导致在将Cr从海水去除到缺氧沉积物过程中出现同位素分馏。对氧化还原分层系统的大量研究表明，在缺氧水柱去除过程中，Cr同位素分馏是一个普遍现象。这对利用缺氧沉积物δ53Cr重建古海水δ53Cr值具有重要意义。纠正这种分馏需要更好地了解其控制因素，这将需要更多关于沉积物陷阱、孔隙水和缺氧环境中氧化还原特异性水柱样本的数据。
{"title":"Chromium isotope fractionation in the redox-stratified Chesapeake Bay","authors":"Debbrota Mallick , Xiangli Wang , Marzia Miletto , Jeffrey W. Krause , Daniel C. Ohnemus , Noah J. Planavsky , George W. Luther , Timothy W. Lyons , Bradley M. Tebo","doi":"10.1016/j.apgeochem.2025.106671","DOIUrl":"10.1016/j.apgeochem.2025.106671","url":null,"abstract":"<div><div>The chromium (Cr) stable isotope compositions of sedimentary rocks have been used to track the evolution of oxygen levels in Earth's ocean-atmosphere system. However, the Cr isotope fractionation during transfer of dissolved Cr to sediments is still unclear. The Chesapeake Bay is a seasonally redox-stratified estuary (oxic surface water overlying euxinic, or sulfide-bearing, deep water) and thus provides a good opportunity to investigate Cr isotope fractionation in euxinic systems. Here we report total dissolved Cr concentrations and stable isotope compositions (δ<sup>53</sup>Cr) of a water column in this estuary. As salinity increases from 7.51 in the oxic surface water to 19.22 in the euxinic deep water, total dissolved Cr concentration decreases from 1.21 nmol kg<sup>−1</sup> to 0.51 nmol kg<sup>−1</sup>, while δ<sup>53</sup>Cr decreases from 0.60 ‰ to −0.41 ‰. Explaining these data requires partial reduction of Cr(VI) to Cr(III) followed by incomplete scavenging of Cr(III) from solution, which leads to isotope fractionation during removal of Cr from seawater to anoxic sediments. An extensive compilation of redox-stratified systems suggests that Cr isotope fractionation during removal from anoxic water column is a common phenomenon. This has major implications for using the δ<sup>53</sup>Cr of anoxic sediments to reconstruct paleo-seawater δ<sup>53</sup>Cr values. Correcting for such fractionation will require better understanding of its governing factors, which would need more data for sediment trap, porewater, and redox-specific water column samples from anoxic settings.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106671"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881535","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 : 2026-01-01Epub Date: 2025-11-03DOI: 10.1016/j.apgeochem.2025.106611
Fiona J. Weiss, Leon Keim, Kai Wendel, Holger Class
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 rather than the activity of , 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.
{"title":"Implementation Pitfalls for carbonate mineral dissolution — A technical note","authors":"Fiona J. Weiss, Leon Keim, Kai Wendel, 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":"2026-01-01","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}
Pub Date : 2026-01-01Epub 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":"2026-01-01","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 : 2026-01-01Epub 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":"2026-01-01","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 : 2026-01-01Epub 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":"2026-01-01","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 : 2026-01-01Epub Date: 2025-11-17DOI: 10.1016/j.apgeochem.2025.106609
Dahai Wang , Chuanshun Zhi , Xiaonong Hu , Zhen Wu , Wei Song , Jian Wang , Xianrui Huang , Fan Yang , Yufei Jiao , Yuxi Li
Coastal sediments, located at the terrestrial–marine interfaces and subject to strong salinity gradients, harbor distinct microbial communities that play indispensable roles in sustaining carbon, nitrogen, and sulfur cycling, yet the responses to salinization remain insufficiently understood. This study aims to characterize microbial community structures within coastal sediments by employing high-throughput sequencing of the 16S rRNA gene. Furthermore, we utilized the FAPROTAX and PICRUSt2 prediction tools to elucidate microbial functions and biogeochemical cycling processes in these sediment ecosystems. The results revealed that increasing salinity significantly increased microbial α-diversity and promoted the expansion of salt-tolerant microbial populations. The salinity-driven increase in microbial network complexity was accompanied by more pronounced competitive interactions. Salinity variations also significantly altered the microbial functions associated with carbon, nitrogen, and sulfur cycling in the sediments. In low-salinity environments, the ability to decompose complex carbon sources was higher, while in high-salinity environments, microbial communities relied more on chitin degradation, starch degradation, and reductive acetogenesis to cope with the high-salinity, low-oxygen conditions. In the nitrogen cycle, mild salinization promoted denitrification, but in the later stages of salinization, high salinity suppressed denitrification, while nitrogen fixation was enhanced in high-salinity environments. The sulfur cycle, both sulfur oxidation and reduction processes were active in medium-salinity sediments, whereas sulfur oxidation was more pronounced and sulfur reduction was diminished in high-salinity sediments, particularly sulfide oxidation and thiosulfate oxidation were enhanced, while dissimilatory sulfate reduction was weakened. This study reveals the effects of salinity gradients on sediment microbial communities and their functions, providing theoretical support for future ecological restoration and environmental management.
{"title":"Impact of salinity gradient on sediment microbial communities and the functions of carbon, nitrogen, and sulfur cycling in coastal zone","authors":"Dahai Wang , Chuanshun Zhi , Xiaonong Hu , Zhen Wu , Wei Song , Jian Wang , Xianrui Huang , Fan Yang , Yufei Jiao , Yuxi Li","doi":"10.1016/j.apgeochem.2025.106609","DOIUrl":"10.1016/j.apgeochem.2025.106609","url":null,"abstract":"<div><div>Coastal sediments, located at the terrestrial–marine interfaces and subject to strong salinity gradients, harbor distinct microbial communities that play indispensable roles in sustaining carbon, nitrogen, and sulfur cycling, yet the responses to salinization remain insufficiently understood. This study aims to characterize microbial community structures within coastal sediments by employing high-throughput sequencing of the 16S rRNA gene. Furthermore, we utilized the FAPROTAX and PICRUSt2 prediction tools to elucidate microbial functions and biogeochemical cycling processes in these sediment ecosystems. The results revealed that increasing salinity significantly increased microbial α-diversity and promoted the expansion of salt-tolerant microbial populations. The salinity-driven increase in microbial network complexity was accompanied by more pronounced competitive interactions. Salinity variations also significantly altered the microbial functions associated with carbon, nitrogen, and sulfur cycling in the sediments. In low-salinity environments, the ability to decompose complex carbon sources was higher, while in high-salinity environments, microbial communities relied more on chitin degradation, starch degradation, and reductive acetogenesis to cope with the high-salinity, low-oxygen conditions. In the nitrogen cycle, mild salinization promoted denitrification, but in the later stages of salinization, high salinity suppressed denitrification, while nitrogen fixation was enhanced in high-salinity environments. The sulfur cycle, both sulfur oxidation and reduction processes were active in medium-salinity sediments, whereas sulfur oxidation was more pronounced and sulfur reduction was diminished in high-salinity sediments, particularly sulfide oxidation and thiosulfate oxidation were enhanced, while dissimilatory sulfate reduction was weakened. This study reveals the effects of salinity gradients on sediment microbial communities and their functions, providing theoretical support for future ecological restoration and environmental management.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106609"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555195","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 : 2026-01-01Epub Date: 2025-12-24DOI: 10.1016/j.apgeochem.2025.106668
Yuyang He
Isotope geochemistry examines the geochemical properties of isotopes within the same element, which are influenced by subtle mass differences. A common assumption in traditional isotope theories is that variations in isotope ratio (R) are sufficiently small to be considered negligible, expressed as 1+RX ≈ 1+RY, named Negligible Isotope Ratio Variation Assumption. Here, X and Y represent sample and standard in the delta notations, distinct endmembers in mixing models, or residual components at progressive stages in Rayleigh distillation models. While this assumption simplifies theoretical models, it may fail when dealing with isotopically enriched or depleted samples, such as synthetic tracers (e.g., 18O-enriched water), or extraterrestrial samples (e.g., hydrogens in solar wind). Moreover, in Rayleigh distillation processes, the R value of residual phases can theoretically approach infinity, significantly deviating from the initial R0 value, rendering an important simplification in classical Rayleigh distillation model invalid. To quantify errors arising from this assumption, this study conducted rigorous mathematical analyses. The results demonstrate that the error in binary mixing models depends on the R value differences between endmembers, while Rayleigh distillation models exhibit a maximum error of ∼1‰ under isotope fractionation factors of 0.9 to 1.1, independent of isotope abundance. These findings highlight the robustness of certain approximations while emphasizing the need to consider model limitations in specific scenarios.
{"title":"Negligible isotope ratio variation assumption: Significant errors in mixing model but minimal impact on Rayleigh distillation model","authors":"Yuyang He","doi":"10.1016/j.apgeochem.2025.106668","DOIUrl":"10.1016/j.apgeochem.2025.106668","url":null,"abstract":"<div><div>Isotope geochemistry examines the geochemical properties of isotopes within the same element, which are influenced by subtle mass differences. A common assumption in traditional isotope theories is that variations in isotope ratio (<em>R</em>) are sufficiently small to be considered negligible, expressed as 1+<em>R</em><sub>X</sub> ≈ 1+<em>R</em><sub>Y</sub>, named Negligible Isotope Ratio Variation Assumption. Here, X and Y represent sample and standard in the <em>delta</em> notations, distinct endmembers in mixing models, or residual components at progressive stages in Rayleigh distillation models. While this assumption simplifies theoretical models, it may fail when dealing with isotopically enriched or depleted samples, such as synthetic tracers (e.g., <sup>18</sup>O-enriched water), or extraterrestrial samples (e.g., hydrogens in solar wind). Moreover, in Rayleigh distillation processes, the <em>R</em> value of residual phases can theoretically approach infinity, significantly deviating from the initial <em>R</em><sub>0</sub> value, rendering an important simplification in classical Rayleigh distillation model invalid. To quantify errors arising from this assumption, this study conducted rigorous mathematical analyses. The results demonstrate that the error in binary mixing models depends on the <em>R</em> value differences between endmembers, while Rayleigh distillation models exhibit a maximum error of ∼1‰ under isotope fractionation factors of 0.9 to 1.1, independent of isotope abundance. These findings highlight the robustness of certain approximations while emphasizing the need to consider model limitations in specific scenarios.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106668"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881089","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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