Applied Geochemistry最新文献

{"title":"Determination of CO2 and DIC in high-CO2 waters: An application for the analysis of coal mine waters","authors":"Dorothy J. Vesper ,&nbsp;Charles A. Cravotta III ,&nbsp;Lili Lei ,&nbsp;Morgan Wallace ,&nbsp;Camille R. Schaffer","doi":"10.1016/j.apgeochem.2025.106336","DOIUrl":"10.1016/j.apgeochem.2025.106336","url":null,"abstract":"<div><div>The impact of sulfuric-acid weathering on the global carbon cycle is increasingly being recognized as important in both recent and deep time estimates yet remains poorly constrained. Global-scale estimates of CO₂ fluxes are hampered by the lack of data, especially for acidic waters. Mining-impacted groundwaters and associated discharges, which can be acidic and contain CO₂ orders of magnitude greater than atmospheric equilibrium, are chemically unstable at the Earth surface and are often difficult to sample and accurately analyze. The direct CO₂ method used herein is accurate and precise with holding times up to 25 days. This modified method allows for the determination of CO₂ and DIC in samples lacking measurable alkalinity or having high CO₂ pressures; these samples may otherwise be excluded from estimates of regional carbon fluxes. To demonstrate the method, natural and CO₂-treated mine waters with pHs ranging from 3.1 to 7.1 were sampled and found to contain between 2 and 13 mM CO₂ (88–572 mg CO₂/L, 24–154 mg C/L) and 2–21 mM dissolved inorganic carbon, DIC (24–252 mg C/L). In comparison to standard DIC estimation methods, the direct method for analyzing CO₂ and determining corresponding concentrations of DIC is more accurate and reproducible over holding times of several weeks for water samples containing low-to-high CO₂ and with acidic-to-circumneutral pH.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106336"},"PeriodicalIF":3.1,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A 3.5-year rainfall isotope records from northwestern Madagascar featuring 17Oexcess and implication for paleoclimate research","authors":"Ny Riavo G. Voarintsoa","doi":"10.1016/j.apgeochem.2025.106335","DOIUrl":"10.1016/j.apgeochem.2025.106335","url":null,"abstract":"<div><div>The lack of modern rainfall stable isotope datasets can leave a knowledge gap in paleoclimate reconstructions using climate sensitive archivers like stalagmites. This is the case of the growing number of paleoclimate records from Anjohibe Cave, where no local rainfall data has been available. This paper reports the first modern rainfall stable isotopes of hydrogen (δ²H and <em>d-</em>excess) and oxygen (δ¹⁷O and δ¹⁸O), highlighting a novel ¹⁷O_excess proxy, spanning 3.5 years of collection from Mahajanga, the closest city of Anjohibe. These data are compared to the only prior existing rainfall isotope data from Madagascar, which was collected from the capital, Antananarivo. Interpretation of the results was helped with model simulations using ERA5T reanalysis and HYSPLIT back trajectory models. Overall, the rainfall data provide better insights on hydrological processes in Mahajanga, including a better constrain on the latitudinal migration of the Inter-Tropical Convergence Zone (ITCZ) and its impact on the kinetic and equilibrium isotopic effect that is best observed in both <em>d</em>-excess and ¹⁷O_excess.</div><div>Results show that rainfall δ¹⁸O (ranging between −7.9 and + 3.9‰, vs. VSMOW) and δ²H (ranging between −49.8 and + 19.7 ‰, vs. VSMOW) from Mahajanga fit within the Global Meteoric Water Line, and they are best explained by the amount effect. However, both <em>d</em>-excess and ¹⁷O_excess are kinetically affected by evaporation for months receiving &lt;1000 mm of rainfall. These months represents the onset and termination of a rainy summer season, when the ITCZ is positioned further north. Above 1000 mm, both values plateaued at ∼15 ‰ and at ∼20 per meg, respectively, regardless of the amount. These values seem to represent the regional equilibrium value for <em>d</em>-excess and ¹⁷O_excess in Mahajanga, when the air is moist during the southward visit of the ITCZ. It is also noted that Mahajanga ¹⁷O_excess values are at the lower spectrum relative to the global ¹⁷O_excess values (20–30 per meg), which are currently biased toward more northern hemisphere datasets. Anjohibe Cave drip waters (varying between −5.6 and −2.1‰ vs. VSMOW for δ¹⁸O and between −33.9 and −8.3 ‰ vs. VSMOW for δ²H), on the other hand, reflect more mixing of the rainfall values due to epikarst storage effects. Calculation of the isotopic fractionation factor between stalagmite and the drip waters in Anjohibe Cave also suggests a good fit with the global fractionation value, 1000ln¹⁸α = 16.89 ± 0.62 × 10³/T(K) – 27.41 ± 2.14, and serves as an excellent motivation to develop future ¹⁷O_excess records from stalagmites in the region.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106335"},"PeriodicalIF":3.1,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aqueous solubilities in the apatite solid-solution system with double co-substitution on both Ca–Sr cation and OH–F anion sublattice positions","authors":"Michael Kersten","doi":"10.1016/j.apgeochem.2025.106323","DOIUrl":"10.1016/j.apgeochem.2025.106323","url":null,"abstract":"<div><div>To investigate the potential for Sr-90 radionuclide sequestration by apatite phases in contaminated soils and aquifers, the solubility product constants of solid solutions in the apatite supergroup system (Ca,Sr)₅(PO₄)₃(OH,F) were studied. Binary hydroxyl- and fluorapatite solid solutions of varying compositions were synthesized hydrothermally at 200 °C and characterized by using Rietveld and chemical analysis. The lattice axis lengths and cell volumes exhibited a linear increase with increasing Sr content, adhering to Vegard's law and indicating mixing without mixing gaps in the solid-solution system. Dissolution studies were conducted at 25 °C through aqueous batch equilibrium experiments. Aqueous solubility increased with the mole fraction of Sr. However, batch equilibration over weeks led to a stoichiometric rather than a true equilibrium state. Such stoichiometric dissolution of a solid solution is commonly observed in low-solubility phases such as apatite minerals. Stoichiometric saturation for solid solutions corresponds to equal molar Gibbs energy functions of the solid and aqueous phases, which can be represented by an “equal-G curve” (EGC) in Lippmann diagrams. Stoichiometric solubility product constants <em>K</em>_st were calculated from the solute activities in the dissolution experiments. These constants align along the straight EGC line connecting the endmember solubility product constants. The excess Gibbs energy of mixing in the solid phase is therefore zero indicating formation of an ideal solid solution system. Correct binary Lippmann phase diagrams were successfully plotted for the first time for substituting cations with stoichiometric factors greater than unity. These diagrams allow for the prediction of solubilities across any solid solution composition, including co-substitutions in both the cation and anion sublattices as represented for the first time by a quaternary Lippmann diagram. The results illustrate that substitution of Ca by Sr increases the solubility of the resulting solid solutions under short-term metastable (stoichiometric) solubility conditions and may lead to preferential Sr release under long-term thermodynamic equilibrium conditions. These findings provide significant environmental implications for Sr-90 radionuclide immobilization using apatite-type minerals.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106323"},"PeriodicalIF":3.1,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mixed nitrogen inputs affected nitrate distribution and biogeochemical processes during ice-covered and ice-free periods in a boreal eutrophic steppe lake basin","authors":"Wenlin Wang ,&nbsp;Jiasen Yang ,&nbsp;Fang Yang ,&nbsp;Liu Yang ,&nbsp;Xiaoguang Xu ,&nbsp;Yulong Tao ,&nbsp;Wen Ao ,&nbsp;Bo Liu ,&nbsp;Qiu Jin ,&nbsp;Guoxiang Wang","doi":"10.1016/j.apgeochem.2025.106333","DOIUrl":"10.1016/j.apgeochem.2025.106333","url":null,"abstract":"<div><div>Nitrogen enrichment from nitrate is a significant contributor to water quality eutrophication in various freshwater basins. However, the input pathways and transformation processes of nitrate remain unclear, particularly during different hydrological processes in boreal eutrophic steppe lake basins that are susceptible to human activity and climate change stressors. In this study, we experimentally investigate the nitrogen sources, transport and transformation in the high-latitude Hulun Lake basin during both ice-covered and ice-free periods using the dual stable isotopes of nitrate (δ¹⁵N–NO₃^- and δ¹⁸O–NO₃^-) with the Stable Isotope Analysis in R (SIAR) model. Our results indicate that nitrate input contributed to water body eutrophication in the Hulun Lake basin, with varying inputs during different hydrological processes. Our quantitative analysis reveals that during the ice-covered period, manure/sewage water (MS) was the dominant nitrate input pathway, accounting for 55.3%, while atmospheric precipitation (AP) contributed the most at 49.8% during the ice-free period. The primary transport and transformation process of nitrate was further identified as nitrification instead of denitrification, as evidenced by the Cl⁻ and NO₃⁻/Cl⁻ levels and redundancy analysis. This study highlights the complexity of nitrate input pathways and transformation processes under different hydrological conditions and emphasizes their significant impact on the nitrogen cycle and ecology of water environments in boreal steppe lake basins.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"182 ","pages":"Article 106333"},"PeriodicalIF":3.1,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143479571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Increasing anthropogenic contributions on hydrochemical evolution of groundwater in the Yellow River basin over the past decade","authors":"Feisheng Feng ,&nbsp;Guangyong Chen ,&nbsp;Tingting Yao ,&nbsp;Yu Wei ,&nbsp;Yongping Shan ,&nbsp;Wanli Su","doi":"10.1016/j.apgeochem.2025.106331","DOIUrl":"10.1016/j.apgeochem.2025.106331","url":null,"abstract":"<div><div>The temporal evolution of groundwater chemistry is crucial for guiding sustainable water resource management. In China, the Yellow River Basin features active geological structures, diverse lithology, and significant human impacts, leading to unclear patterns and factors governing groundwater chemistry evolution. In this study, we investigated the characteristics, sources, and controlling factors of groundwater chemistry in the Yellow River Basin during the period of 2011–2022, with a view to providing guidance for water chemistry management in the region. The results indicate that over time, major ions (Na⁺, Mg²⁺, Cl⁻, SO₄²⁻, NO₃⁻, and F⁻) in the Yellow River Basin's groundwater rise then fall, with pH initially increasing before stabilizing at a mild alkaline level. The anions in groundwater chemistry are dominated by HCO₃⁻, which accounts for 38.89–60.78% of the anion concentration equivalent, and cations are dominated by Na⁺, which accounts for 31.43–72.22%. Hydrochemical types shift among HCO₃–Ca, Cl–SO₄–Na, and mixed HCO₃–Ca–Mg, with Cl–SO₄–Na type correlating positively with human activity level. Dissolution of minerals are the primary sources of groundwater chemistry. Hydrochemical evolution is driven by rock weathering alongside human activities such as sewage discharge and fertilizer application. Initially, mineral weathering was the key factor, with the chemical composition becoming dynamically altered as human activity increased. In summary, the groundwater chemistry in the Yellow River Basin mainly stems from mineral reactions, initially by rock weathering and later affected by rising human activities. This study advances knowledge of groundwater geochemical dynamics in the Yellow River Basin, supporting improved management and sustainable water resource use.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106331"},"PeriodicalIF":3.1,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143520057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling hydrogen induced geochemical reaction mechanisms through coupled geochemical modeling and machine learning","authors":"D.L. Driba,&nbsp;Lauren E. Beckingham","doi":"10.1016/j.apgeochem.2025.106330","DOIUrl":"10.1016/j.apgeochem.2025.106330","url":null,"abstract":"<div><div>Underground hydrogen storage (UHS) provides a promising large-scale, long-term energy storage solution. A reasonable recovery of stored hydrogen is critical for a successful storage scheme. However, in subsurface reservoirs hydrogen is subject to active geochemical reactions that might result in hydrogen loss. In this study, we implemented a geochemical modeling approach coupled with an unsupervised machine learning technique called non-negative matrix factorization (NMF) to unravel the complex brine-rock-H₂ geochemical processes responsible for hydrogen losses, with particular focus on sulfate reduction reactions. NMF is applied to modeled mineral evolution and fluid component profiles to retrieve profiles that can be interpreted to more easily assess competing processes. NMF decouples simulated competing equilibrium reactions. This facilitates separation of overlapping reaction profiles from redox processes, dissolution fronts, and secondary precipitation while considering the effects of simulation parameters such as salinity, temperature, and total H₂ pressure. NMF successfully discriminates these competing effects in nonlinear ways, allowing robust interpretation. In addition, NMF reveals subtle coupled mineral associations and reaction fronts that are invisible to conventional model analysis. This integrated approach strengthens the conceptual understanding of complex nonlinear hydrogen-brine-rock interactions and advances geochemical research on UHS systems to resolve complexities in modeled geochemical systems without the need for direct experiments or prior knowledge. This study highlights the efficacy of combining geochemical modeling with machine learning techniques to enhance the interpretability of the intricate geochemical simulation output through deciphering the overlapping reaction path that cannot be achieved only using conventional analysis of geochemical models alone.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106330"},"PeriodicalIF":3.1,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Country-scale lithogeochemical interpretation of stream sediment dataset in central Cameroon: Toward an integrated tool to support national geophysics surveys and geological mapping programs","authors":"G. Vic ,&nbsp;J. Bernard ,&nbsp;M. Chevillard ,&nbsp;L. Bailly ,&nbsp;C. Ndongue ,&nbsp;Y. Itard ,&nbsp;J. Melleton ,&nbsp;G. Martelet ,&nbsp;E. Kouokam ,&nbsp;E. Fournier ,&nbsp;R. Couëffé ,&nbsp;D. Keutia","doi":"10.1016/j.apgeochem.2025.106321","DOIUrl":"10.1016/j.apgeochem.2025.106321","url":null,"abstract":"<div><div>In the frame of a 1:200,000 mapping project of Cameroon coordinated by PRECASEM for the Ministry of Mine, Industry and Technological Development (MINMITD), between 2016 and 2021, and carried out by BRGM-GTK-BEIG3 Consortium, a dataset of nearly 15,500 stream sediment samples were collected, at an average sampling density of 1 sample per 10 km², over an area of some 157,000 km², and analysed for 49 major and traces elements plus gold. The first aim of the geochemical survey was to identify, at the country scale, metallic anomalies and districts to promote the mining potential of Cameroon to mining investors.</div><div>In order to expand the use of this unique geochemical dataset, multivariate geostatistical processing by Principal Component Analysis (PCA) and Agglomerative Hierarchical Clustering (AHC) was performed for lithogeochemical purpose. This processing enabled the identification of several lithogeochemical signatures which match very well with the main geological domains and formations obtained by conventional geological field survey. Moreover, in areas covered by thick lateritic profile like in the Adamawa-Yadé subdomain, the geostatistical processing was able to identify the granitic nature of the bedrock.</div><div>Secondly, the geochemical results obtained for U, K and Th on stream sediments were handled by inverse distance interpolation (IDW), and represented in a ternary combination in the RGB colour space to generate a pseudo-radiometric map to be compared with the high-resolution regional-scale airborne geophysical survey (magnetic and radiometric data) undertaken prior to the beginning of the mapping project. Similarities between both maps are remarkable. Moreover, the pseudo-radiometric map appears also more discriminant in areas covered by thick forest and thick lateritic profile, in humid and swampy environments allowing the identification of structural features and geochemical contrasts unrevealed by the airborne survey.</div><div>This contribution shows that stream sediment regional-to country-scale dataset should not only be used to highlight the mining potential of the studied area, but also represent a powerful tool, once derived in lithogeochemical and pseudo-radiometric interpretative maps, which can be efficiently used to decipher the major geological contrasts and structural feature of the country rocks. This information is of primary importance to define and calibrate the targets, logistics and costs of the geological field survey classically associated with these national programs, especially in areas with poor outcrops and/or not covered by airborne geophysical surveys.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106321"},"PeriodicalIF":3.1,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143520056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in Mg-Cu-Zn isotopic features in a system red cracking bolete – soil over an extended period","authors":"Alexandre V. Andronikov,&nbsp;Irina E. Andronikova,&nbsp;Ondrej Sebek,&nbsp;Eva Martinkova,&nbsp;Marketa Stepanova","doi":"10.1016/j.apgeochem.2025.106315","DOIUrl":"10.1016/j.apgeochem.2025.106315","url":null,"abstract":"<div><div>We studied Mg–Cu–Zn isotope systematics of the <em>Xerocomellus chrysenteron</em> mushroom samples collected during two consecutive growing seasons from three sites underlain by granite, amphibolite, and serpentinite bedrock. None of the elements analyzed in mushrooms (Mg, Cu, Zn) displayed site-dependency in concentrations. The studied soils were depleted in ²⁶Mg isotope (δ²⁶Mg = −0.78 to −0.30‰) and displayed a very wide range of δ⁶⁵Cu values (−0.85 to +0.67‰). Values of δ⁶⁶Zn were mostly negative for soils from the granite-based site (−0.33 to +0.07‰), positive for soils from the amphibolite-based site (+0.03 to +0.12‰), and only slightly deviated from zero for soils from the serpentinite-based site (−0.09 to +0.09‰). Observed difference in isotope compositions between the mushroom-bearing and mushroom-free soils was most likely due to the presence of mushroom's mycelium in the mushroom-bearing soils. Isotopes of Mg, Cu, and Zn fractionated to different extent during both uptake and within-mushroom translocation. Mushrooms displayed higher uptake of isotopically light Mg (Δ²⁶Mg_FB-soil = −0.71 to −0.12‰), isotopically heavy Zn (Δ⁶⁶Zn_FB-soil = 0.61–0.91‰), and isotopically variable Cu (Δ⁶⁵Cu_FB-soil = −1.22 to +1.03‰). The ranges of the within-mushroom isotope fractionation were significant: Δ²⁶Mg displayed a total range of values of 1.09‰; Δ⁶⁵Cu, of 0.65‰; and Δ⁶⁶Zn, of 0.38‰. No uniform scheme of the within-mushroom isotope fractionation was observed for any studied element.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"182 ","pages":"Article 106315"},"PeriodicalIF":3.1,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of Mn oxides precipitated by passive treatment of Appalachian coal mine wastes","authors":"Florence T. Ling ,&nbsp;Margaret A.G. Hinkle ,&nbsp;Jeffrey E. Post ,&nbsp;Eugene S. Ilton ,&nbsp;Peter J. Heaney","doi":"10.1016/j.apgeochem.2025.106317","DOIUrl":"10.1016/j.apgeochem.2025.106317","url":null,"abstract":"<div><div>Coal mine drainage sites across Pennsylvania often contain high concentrations of Mn, along with contaminants such as Zn, Ni, Al, Co, and Fe. Passive treatment systems consisting of cobbled limestone/dolostone beds have been used to promote Mn oxidative precipitation, which can also remove other metals via incorporation into or adsorption onto the resulting Mn oxide minerals. Here, we examine Mn oxide precipitates and aqueous geochemistry of a dolostone-lined passive coal mine drainage treatment system in Glasgow near Bellwood, PA. We focus on characterizing the precipitated Mn oxide phases with exceptional detail to bridge our understanding of synthetic Mn oxides from the laboratory into the field. Mn oxides were collected and analyzed using X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscopy, X-ray absorption fine structure analysis, and Raman spectroscopy. Water samples were also collected and analyzed for pH and for metal concentrations using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Analyses of the coatings on the cobbles revealed mixtures of tectomanganates and phyllomanganates, including todorokite and both triclinic and hexagonal birnessite/buserite-like structures. Raman mapping showed that Mn oxide phases are intermixed at the micron-scale. Differences in the compositions of triclinic and hexagonal birnessite-like phases were observed in the samples, with triclinic birnessites containing higher Ca, Mg, Al, Co, and Ni concentrations than hexagonal birnessites. Water analyses indicated that the treatment system was effective at removing Mn, Zn, Ni, and Fe as water infiltrated the beds of cobbled dolostone.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106317"},"PeriodicalIF":3.1,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143528759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enrichment mechanisms of natural hydrogen and predictions for favorable exploration areas in China","authors":"Shuai Wang ,&nbsp;Shu Jiang ,&nbsp;Xuelian Huang ,&nbsp;Shihua Qi ,&nbsp;Jingyu Lin ,&nbsp;Yongjie Han ,&nbsp;Yang Wang ,&nbsp;Xueqing Wu ,&nbsp;Guodong Zheng","doi":"10.1016/j.apgeochem.2025.106316","DOIUrl":"10.1016/j.apgeochem.2025.106316","url":null,"abstract":"<div><div>Natural hydrogen (H₂) is widely distributed and holds significant potential as future energy source. Global exploration and development efforts have identified many promising regions for natural H₂ reservoirs. This review examines the origins, migration, and enrichment mechanisms of natural H₂, focusing on the primary geological environments and genetic types of known high-concentration H₂ reservoirs worldwide. We conclude that H₂-rich natural gas tends to accumulate in specific geological settings, including tectonically active zones such as ophiolite belts at convergent plate margins and rift zones, as well as tectonically stable regions like the Precambrian continental basement. The exploration and development of natural H₂ in China are at an early stage, but the Chinese continental geology shows promising conditions for high-concentration H₂ resources. Based on the identified natural H₂ occurrence patterns, we predict favorable exploration directions for natural H₂ in China, particularly in the subduction zones of the Pacific Plate and the North China Plate-South China Plate, the collision zone between the Siberian Plate and the Tarim Plate, and the basins surrounding the Qiangtang-South China Plate and Gondwana Plate collision zone.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"182 ","pages":"Article 106316"},"PeriodicalIF":3.1,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471454","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}