Aquatic Geochemistry最新文献

{"title":"Unraveling the Role of Capillarity in Arsenic Mobility: Insights from a Sedimentary–Karstic Aquifer in Semiarid Soil","authors":"Andrea Gómez-Hernández, Nadia Martínez-Villegas, Jejanny Lucero Hernández-Martínez, Javier Aguilar Carrillo de Albornoz, Diana Meza-Figueroa","doi":"10.1007/s10498-024-09422-x","DOIUrl":"10.1007/s10498-024-09422-x","url":null,"abstract":"<div><p>Arsenic (As) contamination in soil and groundwater poses significant environmental and human health concerns. While chemical mechanisms like solubility equilibria, oxidation–reduction, and ionic exchange reactions have been studied to understand As retention in soil, the influence of capillarity on As transport remains poorly understood, particularly in semiarid soils with broader capillary fringes. This research aims to shed light on the capillary contribution to As attenuation and mobilization in the groundwater, focusing on degraded soil in the northeast of San Luis Potosí, Mexico. Groundwater surveys revealed a remarkable depletion of As concentrations from 91.50 to 11.27 mg L<sup>−1</sup>, indicating potential As sorption by the underlying shallow aquifer. We examined soil samples collected from the topsoil to the saturated zone using advanced analytical techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and wet chemical analyses. Our findings unveiled the presence of three distinct zones in the soil column: (1) the A horizon with heavy metals, (2) dispersed calcium sulfate dihydrate crystals and stratified gypsum, and (3) a higher concentration of arsenic in the capillary fringe. Notably, the capillary fringe exhibited a significant accumulation of As, constituting 40% (169.22 mg kg<sup>−1</sup>) of the total arsenic proportion accumulated (359.27 mg kg<sup>−1</sup>). The arsenic behavior in the capillary fringe solid phase correlated with total iron behavior, but they were distributed among different mineral fractions. The labile fraction, rich in arsenic, contrasted with the more recalcitrant fractions, which exhibited higher iron content. Further, thermodynamic stability assessments using the geochemical code PHREEQC revealed the critical role of Ca<sub>5</sub>H<sub>2</sub>(AsO<sub>4</sub>)<sub>4</sub>:9H<sub>2</sub>O in controlling HAsO<sub>4</sub><sup>2−</sup> and the formation of HAsO<sub>4</sub>:2H<sub>2</sub>O and CaHAsO<sub>4</sub>:H<sub>2</sub>O. During experimentation, we observed arsenate dissolution, indicating the potential mobilization of As in aqueous species. This mobilization was found to vary depending on redox conditions and may become labile during flooding events or water table variations, especially when As concentrations are low compared to metal cations, as demonstrated in our experiments. Our research underscores the significance of developing accurate geochemical conceptual models that incorporate capillarity to predict As leaching and remobilization accurately. This study presents novel insights into the understanding of As transport mechanisms and suggests the necessity of considering capillarity in geochemical models. By comprehending the capillary contribution to As attenuation, we can develop effective strategies to mitigate As contamination in semiarid soils and safeguard groundwater quality, thereby addressing crucial environmental and public he","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"30 2","pages":"49 - 71"},"PeriodicalIF":1.7,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140565023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Source and Formation of Boron Deposits in Mahai Basin on the Northern Qinghai-Tibet Plateau: Clues from Hydrochemistry and Boron Isotopes","authors":"Honglu Xiang,&nbsp;Qishun Fan,&nbsp;Qingkuan Li,&nbsp;Yongsheng Du,&nbsp;Guang Han,&nbsp;Jiubo Liu,&nbsp;Hongkui Bai","doi":"10.1007/s10498-024-09425-8","DOIUrl":"10.1007/s10498-024-09425-8","url":null,"abstract":"<div><p>There are typical salt lake-type borate deposits in the northern Qaidam Basin, which are mainly distributed in Da Qaidam Lake (DQL), Xiao Qaidam Lake, and Mahai Basin (MHB). DQL has deposited famous solid borates and enriched a large number of brine boron deposits. It is the earliest industrial production base in China. Nanbaxian (NBX) to the west of DQL is a unique area where solid borates are deposited in MHB. Although there are three salt lakes in the MHB, borate deposits were only deposited in the salt pits of NBX, and the formation process of these borate deposits remains to be clarified. In this study, the major elements, boron contents, and d¹¹B values in the water and sediments of NBX were investigated in conjunction with the B-Na-Mg equivalence diagrams and relevant data from other salt lakes to elucidate the source of boron in MHB and the depositional conditions of borate minerals in NBX. The results are as follows: (1) The source of boron in NBX differs from that in three salt lakes in MHB. The source in NBX is mainly constrained by the weathering and fluid-rock (Boron-bearing ultra-high pressure metamorphic belt) interaction, while that in Dezongmahai and Niulangzhinv–Balunmahai lakes are primarily controlled by river water and anticlinal brine, respectively. (2) The high boron content (0.28 to 41.38 mg/L) and low d¹¹B values (- 34.71‰ to - 6.14‰) of the water-soluble phase of sediments in NBX are consistent with geochemical characteristics (d¹¹B: - 23.67‰ to - 3.0‰) of borates in DQL, demonstrating that the re-dissolution of borate deposits in NBX. (3) Deposition of borate minerals in the MHB requires ionic equivalents of Mg, Na, and B to 0.02 to 0.4, 0.25 to 0.75, and 0.2 to 0.7, respectively. Additionally, the brine hydrochemistry in which the borate are deposited must be of the carbonate or sulfate type, and the brine water should be greater than 8 in pH and 400 mg/L in boron content. This study provides a theoretical basis for exploring and exploiting salt lake-type borate deposits.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"30 3","pages":"143 - 161"},"PeriodicalIF":1.7,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140565019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct Salinity Effect on Absorbance and Fluorescence of Chernozem Water-Extractable Organic Matter","authors":"Vladimir A. Kholodov,&nbsp;Natalia N. Danchenko,&nbsp;Aliya R. Ziganshina,&nbsp;Nadezhda V. Yaroslavtseva,&nbsp;Igor P. Semiletov","doi":"10.1007/s10498-024-09423-w","DOIUrl":"10.1007/s10498-024-09423-w","url":null,"abstract":"<div><p>Soil-derived dissolved organic matter (DOM) has a significant impact on aquatic ecosystems. Identifying the fluorescence signatures of DOM from different soils in river and sea waters can provide valuable insights into its migration patterns. This makes crucial assessing the contributions of pH, salinity, and other milieu parameters to the variability of DOM optical properties. Present study investigates the changes in DOM of Chernozems under varying salinity using UV–visible absorbance spectroscopy and 3D-fluorescence spectroscopy coupled with parallel factor analysis (EEMs-PARAFAC). Water-extractable organic matter (WEOM) extracted from soils of two field experiments of contrasting land use: long-term bare fallow (LTBF) and annually mown steppe (Steppe), was used as a proxy for DOM. Diluted extracts were incubated with varying NaCl concentrations in the dark and then examined. Steppe WEOM exhibited fair constancy of optical parameters under increasing salinity, while significant changes of the optical indices and of PARAFAC components’s loadings were observed for LTBF WEOM. The remarkable stability of the Steppe WEOM can be attributed to its chemical diversity. Two distinct and sufficiently stable humic-like PARAFAC components have the potential to serve as markers of Chernozem DOM. The findings clearly demonstrate that salinity itself slightly reduces absorption and fluorescence and changes some optical indices of WEOM of Chernozems.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"30 1","pages":"31 - 48"},"PeriodicalIF":1.7,"publicationDate":"2024-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139946288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solid-liquid Equilibria (SLE) of the System Containing the Sulfates of Lithium and Potassium at 303.2 and 318.2 K","authors":"Zhihao Yao,&nbsp;Xudong Yu,&nbsp;Zhixing Zhao,&nbsp;Xia Feng,&nbsp;Yousheng Yang,&nbsp;Qi Li,&nbsp;Ying Zeng,&nbsp;Hao Jiang,&nbsp;Yiran Li","doi":"10.1007/s10498-023-09420-5","DOIUrl":"10.1007/s10498-023-09420-5","url":null,"abstract":"<div><p>The solid-liquid phase equilibria of aqueous system containing the sulfates of lithium and potassium (Li₂SO₄ + K₂SO₄ + H₂O) at <i>T</i> = 303.2 and 318.2 K were done by isothermal dissolution method. The phase equilibria data (solubility, density, and refractive index) of the system were determined experimentally. The corresponding solid-liquid phase diagram, density/refractive index versus composition diagrams, were plotted. There are two ternary invariant points and three crystallization regions corresponding to Li₂SO₄·H₂O, LiKSO₄, and K₂SO₄ in the phase diagram of system Li₂SO₄ + K₂SO₄ + H₂O at 303.2 and 318.2 K. A comparision of system Li₂SO₄ + K₂SO₄ + H₂O at different temperature (<i>T</i> = 288.2, 303.2, 318.2 and 348.2 K) shown that the double salt LiKSO₄ was formed in the above mentioned temperatures, and the crystallization region of the LiKSO₄ increases gradually with the increase of temperature.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"30 3","pages":"273 - 286"},"PeriodicalIF":1.7,"publicationDate":"2024-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Short-Term Spatiotemporal Variability in Seawater Carbonate Chemistry at Two Contrasting Reef Locations in Bocas del Toro, Panama","authors":"Katelin Pedersen,&nbsp;Tyler Cyronak,&nbsp;Morgan Goodrich,&nbsp;David I. Kline,&nbsp;Lauren B. Linsmayer,&nbsp;Ralph Torres,&nbsp;Martin Tresguerres,&nbsp;Andreas J. Andersson","doi":"10.1007/s10498-024-09421-y","DOIUrl":"10.1007/s10498-024-09421-y","url":null,"abstract":"<div><p>There is growing concern about the effects of ocean acidification (OA) on coral reefs, with many studies indicating decreasing calcium carbonate production and reef growth. However, to accurately predict how coral reefs will respond to OA, it is necessary to characterize natural carbonate chemistry conditions, including the spatiotemporal mean and variability and the physical and biogeochemical drivers across different environments. In this study, spatial and temporal physiochemical variability was characterized at two contrasting reef locations in Bocas del Toro, Panama, that differed in their benthic community composition, reef morphology, and exposure to open ocean conditions, using a combination of approaches including autonomous sensors and spatial surveys during November 2015. Mean and diurnal temporal variability in both physical and chemical seawater parameters were similar between sites and sampling depths, but with occasional differences in extreme values. The magnitude of spatial variability was different between the two sites, which reflected the cumulative effect from terrestrial runoff and benthic metabolism. Based on graphical vector analysis of TA–DIC data, reef metabolism was dominated by organic over inorganic carbon cycling at both sites, with net heterotrophy and net calcium carbonate dissolution dominating the majority of observations. The results also highlight the potentially strong influence of terrestrial freshwater runoff on surface seawater conditions, and the challenges associated with evaluating and characterizing this influence on benthic habitats. The Bocas del Toro reef is a unique system that deserves attention to better understand the mechanisms that allow corals and coral reefs to persist under increasingly challenging environmental conditions.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"30 1","pages":"1 - 29"},"PeriodicalIF":1.7,"publicationDate":"2024-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10498-024-09421-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139661375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Elemental Variations and Mechanisms of Brines in the Context of Large-Scale Exploitation: A Case Study of Xitaijnar Salt Lake, Qaidam Basin","authors":"Zhanjie Qin,&nbsp;Qingkuan Li,&nbsp;Wenxia Li,&nbsp;Qishun Fan,&nbsp;Tianyuan Chen,&nbsp;Chan Wu,&nbsp;Jianping Wang,&nbsp;Fashou Shan","doi":"10.1007/s10498-023-09419-y","DOIUrl":"10.1007/s10498-023-09419-y","url":null,"abstract":"<div><p>There is limited research on the variations in brine element changes and the factors that influence them during large-scale exploitation. The Xitaijnar Salt Lake in the Qaidam Basin is a large brine lithium deposit. In this study, we investigated the variations in chemical composition and the factors that influence intercrystalline brine at different time periods. Hydrochemistry, mineralogy, and hydrogeochemical simulation methods were employed to understand the brine evolution. Our results indicate that after nearly 20 years of exploitation, the intercrystalline brine still belongs to the magnesium sulfate subtype, with only slight variations in salinity. The concentrations of Na, K, and SO₄ showed a slight increase, while the content of Mg and Cl decreased slightly. The concentrations of B and Li exhibited minor fluctuations. The provenance, water level, and hydraulic connection had minimal influence on the chemical composition of the intercrystalline brine. By contrast, the dynamic dissolution and precipitation of sulfate minerals and halite, as well as drastic changes in hydrological conditions (such as floods), were identified as the main factors affecting the chemical composition of brine. With the large-scale extraction of intercrystalline brine, the content of elements in the salt lake showed a decreasing trend. This can be attributed to the fact that intercrystalline brine is formed through long-term evaporation and concentration. Therefore, during the exploitation process, it is crucial to monitor the hydrochemical variations of intercrystalline brine and understand the controlling factors. The results of this study may prove useful for the sustainable development and utilization of salt lake resources worldwide.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"30 3","pages":"121 - 141"},"PeriodicalIF":1.7,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10498-023-09419-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138958763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"A Study on Ikaite Growth in the Presence of Phosphate","authors":"Samuel B. Strohm,&nbsp;Giuseppe D. Saldi,&nbsp;Vasileios Mavromatis,&nbsp;Wolfgang W. Schmahl,&nbsp;Guntram Jordan","doi":"10.1007/s10498-023-09418-z","DOIUrl":"10.1007/s10498-023-09418-z","url":null,"abstract":"<div><p>Phosphate is a common component in natural growth solutions of ikaite. Although phosphate often occurs as a minor constituent, its presence may promote the formation of ikaite as it significantly inhibits the precipitation of calcite. The interactions of phosphate with ikaite and the role of a potential uptake of phosphate by ikaite, however, are poorly understood. In this study, the influence of phosphate on ikaite growth at 1 °C was investigated. Ikaite- and calcite-seeded growth experiments were conducted in cryo-mixed-flow reactors at saturation ratios 1.5 ≤ <i>Ω</i>_ikaite ≤ 2.9 (<i>Ω</i> = ionic activity product/solubility product). From these growth experiments, the rate constant <i>k</i> = 0.10 ± 0.03 µmol/m²/s and the reaction order <i>n</i> = 0.8 ± 0.3 were derived for ikaite. The reaction order implies a transport- or adsorption-controlled growth mechanism which supports a low energy pathway of ikaite growth via an attachment of hydrous CaCO₃⁰ complexes without any extensive dehydration of aqueous species as, for instance, required for calcite growth. A potential depletion of aqueous phosphate due to an uptake by ikaite growth was not detectable. Furthermore, growth retardation by phosphate, as known for calcite growth, was not evident. Thus, a significant incorporation of phosphate into growing ikaite could be precluded for the conditions applied in this study. The observed lack of incorporation of phosphate agrees with the previously suggested growth mechanism via the attachment of hydrous CaCO₃⁰ complexes which likely does not facilitate substantial substitution of carbonate by phosphate ions.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"29 4","pages":"219 - 233"},"PeriodicalIF":1.6,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10498-023-09418-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138473233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Effect of Ionic Strength on H2O and Si-Species Stability Field Geometry in pH-Eh Space","authors":"Samuel Bowman,&nbsp;Arkajyoti Pathak,&nbsp;Vikas Agrawal,&nbsp;Shikha Sharma","doi":"10.1007/s10498-023-09417-0","DOIUrl":"10.1007/s10498-023-09417-0","url":null,"abstract":"<div><p>Speciation diagrams in pH-Eh space at some pressure, temperature, and composition are highly useful in indicating the thermodynamic behavior expected in a system. While these diagrams are found frequently throughout geochemical literature, they often overlook the geometric behavior of stability fields and fail to address the specific impacts of ionic strength and fluid composition. Modeling results from the Salton Sea and Krafla geothermal sites suggest a positive correlation between ionic strength and the H₂O_(l) stability field area or reactivity domain. In addition, the Si-bearing species (selected due to the propensity of adverse scale occurrence) within the Salton Sea brine are shifted farther apart than the centroids of the same Si species in the comparatively dilute Krafla. These modeling observations imply that geothermal brines at equilibrium accommodate a larger H₂O reactive field in pH-Eh space, allowing for the possibility that water–rock interactions could occur at pH-Eh conditions that would conventionally be unexpected if ionic strength is not considered.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"29 4","pages":"207 - 218"},"PeriodicalIF":1.6,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial Variation and Influencing Factors of Optical Characteristic of Water Extractable Organic Matter in Soils of Urban Grassland Across Climatic Zones in China","authors":"Baozhu Pan,&nbsp;Siwan Liu,&nbsp;Yitong Ding,&nbsp;Ming Li","doi":"10.1007/s10498-023-09416-1","DOIUrl":"10.1007/s10498-023-09416-1","url":null,"abstract":"<div><p>Dissolved organic matter (DOM) is the most active organic component in terrestrial ecosystems. In this study, 165 soil samples which were dominated by moss were collected from grasslands with similar vegetation in urban residential areas from 55 cities across different climatic zones of China. The water extractable organic matter (WEOM) of samples was analyzed. The results showed that WEOM content ranged from 23.5 to 517.6 mg kg⁻¹ in the soil samples. Four fluorescent components including two tryptophan-like components (C1 and C4) and two humic-like components (C2 and C3) were identified by excitation–emission matrices combined with parallel factor analysis (EEM-PARAFAC). Proportions of humic-like components (C2 + C3) were 54–66%, which is 1.2–2.0 times of the tryptophan-like component proportion (C1 + C4) for all samples. The proportions of C2 and C3 were highest in the tropical monsoon climate (TroM) zone compared to that in the other climatic zones. Structural equation model and decomposition of variation showed that soil nutrient content was the main contributing factor of soil WEOM. Content Total nitrogen content and mean annual temperature (MAT) were the main factors influencing soil HIX but they had the opposite effects. Our results suggested that increasing soil nutrient content contributed the increase in soil WEOM content, but increasing MAT reduced the humification degree of WEOM.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"29 4","pages":"189 - 205"},"PeriodicalIF":1.6,"publicationDate":"2023-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136192531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Occurrence, Chemical, and Pb-isotopic Composition of Uraninite: A Verification of the Effective Source of Uranium in a Granite Aquifer of the Daejeon Area, South Korea","authors":"Jeong Hwang,&nbsp;Keewook Yi","doi":"10.1007/s10498-023-09415-2","DOIUrl":"10.1007/s10498-023-09415-2","url":null,"abstract":"<div><p>Daejeon is well-known in South Korea for having the highest concentrations of uranium in the Jurassic granite aquifer. This study reports the texture and chemistry of uraninite and discusses the potential of uraninite as an effective source mineral of U in granite aquifers based on uraninite dissolution and U-migration. Its texture and mineral chemistry were examined using FE-SEM and EPMA, respectively, to investigate the occurrence of uraninite. The Pb isotope ratios of the minerals in granite were tested to verify their potential as geochemical tracers for elemental migration. The Pb isotope ratios were obtained using a SHRIMP IIe/MC ion microprobe. Uraninite occurred with muscovite and pyrite as large grains of up to 500 μm in length in the altered granite. Coffinite, a secondary U-mineral, occurs in the cracks within uraninite. The uraninite U content ranged from 79.12 to 89.05 wt. % and uraninites have major impurities of Th, and Pb ranged from 1.82 to 3.49 and 2.13 to 2.42 wt. %, respectively. The breakdown of uraninite may result in the redistribution of U and Pb and facilitate U-migration during surface weathering. The Eh–pH conditions of groundwater are suitable for the dissolution of uraninite, and the uranyl carbonate complex ion (UO₂(CO₃)₂²⁻) is the dominant U-species in the study area. The Pb isotope ratios indicated that uraninite contained radiogenic Pb, feldspar contained common Pb, and pyrite contained a mixture of both components. These Pb isotopic signatures indicate that the radiogenic Pb in uraninite has migrated from uraninite to pyrite. Considering the relatively high mobility of U compared to Pb, the migration of radiogenic Pb from uraninite to pyrite suggests that U can also migrate from uraninite to its surroundings when a reaction with groundwater occurs. Based on hydrological conditions and the Pb isotope signature, uraninite is considered a substantial and compelling host mineral for interpreting a source of uranium in the granite aquifer of the study area.</p></div>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"29 3","pages":"173 - 187"},"PeriodicalIF":1.6,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4799048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}