Applied Geochemistry最新文献

{"title":"Water-rock interaction processes in the Devonian aquifer system and Qusaiba Silurian shale of northwestern Saudi Arabia","authors":"Fahad A. Souid,&nbsp;Peter Birkle","doi":"10.1016/j.apgeochem.2025.106527","DOIUrl":"10.1016/j.apgeochem.2025.106527","url":null,"abstract":"<div><div>Water-rock interaction (WRI) processes in Devonian sandstones and underlying Qusaiba Silurian shales in northwestern Saudi Arabia were investigated using the elemental abundance in core samples, groundwater hydrochemistry, and strontium isotopic ratios (⁸⁷Sr/⁸⁶Sr) of rock and groundwater samples. The partitioning of Na, Ca, Mg, K and trace metals (Sr, Ba, Zn, Fe, Mn) from Devonian and Qusaiba rock samples was assessed along five fractions: exchangeable, bound to carbonates, Fe–Mn oxides, organic matter, and residual fraction. Ca comprised the main constituent of the Devonian aquifer host rock, while Na was revealed to be the dominant constituent of the Silurian shales, especially in the exchangeable and the bound-to-carbonate phase. By integrating host rock elemental abundances (n = 17) with groundwater chemistry (n = 74), it was identified that the replacement of inherited Ca by Na represents the dominating ion-exchange process between host rock and groundwater. ⁸⁷Sr/⁸⁶Sr ratios for Devonian groundwater (0.707673–0.711577) and rock cuttings (0.707930–0.712477) are within a similar range, indicating enhanced WRI processes in the Devonian aquifer. The increase in ⁸⁷Sr/⁸⁶Sr with depth is temperature-triggered and attributed to a change in facies from a marine dominated environment of calcareous Devonian sandstones to a terrestrial depositional environment with K-rich terrane. Considerable quantities of Ca, Mg, and K in the Fe–Mn oxide leachates alongside with the inheritance of groundwater to the oxide phase ⁸⁷Sr/⁸⁶Sr ratios suggest the presence of a reducing environment in the Devonian aquifer.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106527"},"PeriodicalIF":3.4,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841185","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":"Quantitative estimation models of relationship between aeolian sand and soil geochemical composition based on machine learning algorithm","authors":"Weiji Wen ,&nbsp;Fan Yang ,&nbsp;Shuyun Xie ,&nbsp;Chengwen Wang ,&nbsp;Yuntao Song ,&nbsp;Yuepeng Zhang ,&nbsp;Weihang Zhou","doi":"10.1016/j.apgeochem.2025.106528","DOIUrl":"10.1016/j.apgeochem.2025.106528","url":null,"abstract":"<div><div>Quantitative estimation models are key to studying the relationship between aeolian sand and soil geochemical composition, as well as for assessing the extent of their influence. However, few studies have developed quantitative models to evaluate how aeolian sand interferes with soil chemical element content, and current approaches primarily rely on provenance analysis through isotopes or major elements. This study combines machine learning regression models with curve regression models to explore the effectiveness of different approaches in constructing quantitative estimation model for aeolian sand interference on soil chemical composition. Our study demonstrated that, of the five different models applied in this study, the Support Vector Regression (SVR) and Random Forest Regression (RFR) models produced the most reliable results. The overall dataset of desert and soil samples conformed to a third-order polynomial fitting model in mathematical relationships, yielding a relatively stable explicit estimation model that quantitatively characterizes the extent of aeolian sand interference on soil chemical composition. This indicates that the Environmental Kuznets Curve (EKC) theory can be applied to geochemical data, offering significant scientific and practical value for exploring the driving mechanisms of surface elements in desert and surrounding areas.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106528"},"PeriodicalIF":3.4,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841186","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":"C-based gas (CH4 and CO2) fluxes from eutrophicated volcanic shallow lakes in Corvo Island (Azores, Portugal)","authors":"J. Virgílio Cruz ,&nbsp;César Andrade ,&nbsp;Duarte Toubarro ,&nbsp;Letícia Ferreira ,&nbsp;Adriano Pimentel ,&nbsp;Fátima Viveiros ,&nbsp;Franco Tassi ,&nbsp;António Cordeiro ,&nbsp;Diogo Braga ,&nbsp;Pedro Raposeiro","doi":"10.1016/j.apgeochem.2025.106529","DOIUrl":"10.1016/j.apgeochem.2025.106529","url":null,"abstract":"<div><div>A study to investigate spatial and temporal variations on the diffusive CO₂ and CH₄ fluxes in two volcanic shallow lakes on Corvo Island (Azores) was made, coupling geochemical and microbial tools. Water in both lakes is from the Na–Cl type, depicting alkaline pH values and low EC (63–90 μS cm⁻¹). The total CO₂ flux (calculated using sequential Gaussian simulation) range between 2.5 t km⁻² d⁻¹ and 6.5 t km⁻² d⁻¹, values closer to the mean value for lakes in the Azores with depth lower than 5 m. Values of total methane flux values are much lower, ranging from 31 to 38 kg km⁻² d⁻¹ falling in the lower range of worldwide datasets. Those emissions depict a seasonal effect, as total GHG emissions (CO₂ plus CH₄) range from 0.66 to 1.1 t CO_2-eq d⁻¹ in warmer conditions, about twice the values during colder periods.</div><div>The microbial characterization also depicts seasonal variations, showing a close relation with the diffusive CO₂ and CH₄ fluxes. During winter, anaerobic and sulfate-reducing bacteria are abundant, when microbial respiration intensifies, while in summer an enrichment in fermentative bacteria, including <em>Clostridiaceae</em> and <em>Enterobacteriaceae</em> is observed. High CH₄ production in summer results is expected from the presence of methanogenic archaea, instead methane oxidation is more relevant in winter, as shown by the higher abundance of methanotrophs, such as <em>Methylomonadaceae</em> and <em>Methylococcaceae</em>. Results show that small volcanic lakes are significative natural sources of C-based greenhouse gases, being CO₂ and CH₄ emissions enhanced by the trophic state of lake ecosystems.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106529"},"PeriodicalIF":3.4,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144858402","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":"Schwertmannite effectively reduced the mobility of arsenic in paddy soil and arsenic uptake by rice: a field experiment","authors":"Jingang Xu,&nbsp;Yangyi Mao,&nbsp;Cheng Yan,&nbsp;Xuan Liu,&nbsp;Baoting Ding,&nbsp;Yan Dong,&nbsp;Bo Zhou,&nbsp;Minjiang Zhang,&nbsp;Dejing Zhang,&nbsp;Murong Wang,&nbsp;Lixiang Zhou","doi":"10.1016/j.apgeochem.2025.106523","DOIUrl":"10.1016/j.apgeochem.2025.106523","url":null,"abstract":"<div><div>Rice (<em>Oryza sativa</em> L.) grain usually accumulated an elevated arsenic (As) in the As-contaminated paddy soil, posing a potential risk to food safety and human health. In this field experiment, three iron-based materials (zero-valent iron, schwertmannite, and ferrous sulfate) as As passivators were applied to investigate their roles in decreasing mobility of soil As and As uptake by rice. The results indicated that NaH₂PO₄-extractable available As and As in soil porewater were significantly decreased by the passivators especially schwertmannite throughout rice growth season. Meanwhile, the amount of iron plaque on rice root surface obviously increased due to application of schwertmannite. In addition, compared with the control without the addition of any passivator, applying zero-valent iron, schwertmannite, and ferrous sulfate decreased As in rice grain by 26.3 %, 46.6 %, and 31.8 %, respectively. Among these passivators, schwertmannite greatly reduced the content of total As and As (Ⅲ) in rice grain, as well as accumulation and translocation of As in rice tissues. In conclusion, schwertmannite was the promising environmental material for controlling As contamination in paddy soil.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106523"},"PeriodicalIF":3.4,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852708","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":"An improved sample preparation method for strontium isotope stratigraphy: case study of early Miocene oysters and foraminifera from the Gulf of Suez, Egypt","authors":"Ting Ruan ,&nbsp;Yue Cai ,&nbsp;Qimei Guo ,&nbsp;Nicholas Christie-Blick ,&nbsp;Ahmed N. El-Barkooky ,&nbsp;Abdel-Moneim El-Araby ,&nbsp;Ahmed Zakaria ,&nbsp;Zhengfan Lin ,&nbsp;Chengcheng Wang ,&nbsp;Raed Badr","doi":"10.1016/j.apgeochem.2025.106509","DOIUrl":"10.1016/j.apgeochem.2025.106509","url":null,"abstract":"<div><div>Strontium isotope stratigraphy (SIS) is a widely employed method for constructing age models in marine sedimentary sequences. This technique relies on the assumption that the strontium isotope (⁸⁷Sr/⁸⁶Sr) composition of seawater is globally homogeneous but evolves predictably over geologic time. A critical requirement for SIS is that the Sr isotope ratios measured in marine calcareous fossils reflect those of the original seawater at the time of biomineralization. However, post-depositional diagenesis can alter these ratios, rendering SIS-derived ages unreliable. To address this issue, careful sample selection and tailored pretreatment protocols are essential. Through parallel leaching experiments, we introduce an improved sample preparation method for SIS. Our approach enhances conventional protocols by using controlled acetic acid concentrations (0.01–0.5 M) for sequential leaching, monitoring Fe/Ca and Mn/Ca ratios of leachates to identify the leachate most likely to preserve the original seawater signatures, and incorporating an ammonium carbonate rinse between leaches to remove loosely bound cations and acid-mobilized contaminants. Contrary to traditional practices, optical observations and geochemical evidence suggest that the final third of unpowdered material dissolved by dilute acetic acid often retains the least-altered primary calcite. We validate our method using oysters and foraminifera from early Miocene deposits in the central Gulf of Suez, Egypt, where independent age constraints confirm the accuracy of our SIS ages. Our results underscore the importance of tailored leaching strategies to mitigate diagenetic biases, thereby enhancing the reliability of SIS in chronostratigraphic applications.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106509"},"PeriodicalIF":3.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771872","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":"Environmental sampling to capture bioavailable strontium isotope distributions on Corsica","authors":"Hannah F. James ,&nbsp;Malte Willmes ,&nbsp;Mélanie Fabre ,&nbsp;Patrice Courtaud ,&nbsp;Kévin Rey ,&nbsp;Marie Balasse ,&nbsp;Rainer Grün ,&nbsp;Christophe Snoeck","doi":"10.1016/j.apgeochem.2025.106511","DOIUrl":"10.1016/j.apgeochem.2025.106511","url":null,"abstract":"<div><div>Strontium isotopes (⁸⁷Sr/⁸⁶Sr) are a powerful geochemical tracer to reconstruct mobility and provenance of bioarcheological and palaeoecological materials. This study presents the first bioavailable Sr isoscape for Corsica based on environmental samples and compares these new results to a global predictive model. The environmental samples consist of plant (n = 245) and ammonium nitrate leached soil (n = 81) samples from 125 sampling sites across the island, creating a comprehensive bioavailable strontium baseline for Corsica. Observed spatial trends in ⁸⁷Sr/⁸⁶Sr are related to the geological age and lithology, with an overall range of 0.7075–0.7169. Soil leachate samples exhibit significantly lower ⁸⁷Sr/⁸⁶Sr values than their paired plant counterparts. The influence of sea spray on terrestrial samples is observed up to 700 m inland around the island. An isoscape was created using Ordinary Kriging within geological units to capture both the influence of geological and environmental conditions on the biologically available ⁸⁷Sr/⁸⁶Sr of Corsica. Compared to a global bioavailable strontium isoscape, the baseline created here shows large differences, especially for samples collected on older lithologies of Variscan Corsica (Carboniferous granite and monzogranite, and Permian rhyolitoid). While the global isoscape predicts the overall spatial patterning of ⁸⁷Sr/⁸⁶Sr values, there is a continued need for extensive environmental sampling to capture the finer scale ⁸⁷Sr/⁸⁶Sr values variability, especially in geologically complex areas. This bioavailable Sr isotope baseline for Corsica allows for the interpretation of mobility from archaeological and palaeoecological samples on the island.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106511"},"PeriodicalIF":3.4,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144756866","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":"ClaySor 2023: Implementation of the 2SPNE SC/CE sorption model and database for deep geological repository safety assessment","authors":"Olha Marinich ,&nbsp;G. Dan Miron ,&nbsp;Dmitrii A. Kulik ,&nbsp;Maria Marques Fernandes ,&nbsp;Bart Baeyens","doi":"10.1016/j.apgeochem.2025.106510","DOIUrl":"10.1016/j.apgeochem.2025.106510","url":null,"abstract":"<div><div>The ClaySor 2023 model package within the GEM-Selektor software includes an updated version of the two-site protolysis non-electrostatic surface complexation and cation exchange model for illite and montmorillonite, as well as the first implementation of the generalised caesium sorption model for illite. These models have been harmonised with the most recent PSI Chemical Thermodynamic Database 2020, resulting in the updated sorption thermodynamic database for illite and montmorillonite (STDB, 2023). STDB 2023 includes surface complexation constants and cation exchange selectivity coefficients for a wide range of radionuclides and transition metals, including Cs(I), Cd(II), Co(II), Fe(II), Mn(II), Ni(II), Pb(II), Ra(II), Zn(II), Am(III), Cm(III) (for illite only), Eu(III), Pu(III, IV), Np(IV, V), Sn(IV), Th(IV), Nb(V), Pa(V), and U(IV, VI). These parameters were derived from extensive experimental sorption data collected over decades at the Paul Scherrer Institute and supplemented with data from the open literature (160 datasets in total). Surface complexation constants and cation exchange selectivity coefficients are now provided with uncertainty estimates, determined using the 95 % confidence intervals obtained via the Monte Carlo sampling method implemented in the GEMSFITS parameter optimization tool. To address gaps caused by missing experimental data, the surface complexation constants for Cd(II) and Fe(II) on illite, as well as those for Pu(III, IV), Np(IV), and U(IV) on both illite and montmorillonite, were estimated based on linear correlations between the stability constants of aqueous and surface complexes. For geochemical calculations, STDB 2023 is supplemented with selectivity coefficients for naturally occurring major cations, sourced from recent literature. The applicability and performance of the model are discussed, and versions of the model and database adapted for the PHREEQC and the Geochemist's Workbench codes are also provided.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106510"},"PeriodicalIF":3.4,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771871","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 phase stability of multinary thiostannates","authors":"Giordano Montegrossi ,&nbsp;Federica Meloni ,&nbsp;Andrea Giaccherini ,&nbsp;Alessandro Veneri ,&nbsp;Matteo Ardit ,&nbsp;Matteo Mannini ,&nbsp;Francesco Di Benedetto","doi":"10.1016/j.apgeochem.2025.106513","DOIUrl":"10.1016/j.apgeochem.2025.106513","url":null,"abstract":"<div><div>This research proposes a comprehensive study of the thermodynamic stability of the structurally similar Cu–Fe–Zn–Sn–S multinary sulfides, critical materials that are pivotal in advancing semiconductor technologies. In light of the scarcity of thermodynamic data in the extant literature concerning a relevant number of mineral phases, the missing data were estimated using a method based on the sum of molecular fragments. Consequently, a novel numerical extrapolation method derived from experimental thermochemical stability constants is integrated with the simulation capabilities of the PHREEQC software. This integration facilitates the meticulous charting (using the formalism of Pourbaix diagrams) of the stability domains of Cu–Fe–Zn–Sn–S multinary sulfides in aqueous environments. The present analysis addresses a critical knowledge gap regarding the aqueous stability of multinary sulfides, while introducing a robust theoretical framework for predicting their environmental and technological viability. This objective is accomplished by delineating the relative stability and precipitation boundaries of the studied phases, thereby providing invaluable insights for the development of these sustainable semiconducting materials. Consequently, this research makes two significant contributions. Firstly, it contributes to the theoretical understanding of multinary sulfide systems. Secondly, it establishes the foundation for their practical application in green technologies.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106513"},"PeriodicalIF":3.4,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771913","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":"Selectivity of tris complexation for Ni(II), Co(II), and Fe(II) and its effect on carbonate precipitation under alkaline conditions","authors":"J.L. Houghton ,&nbsp;J.M. Haywood ,&nbsp;Y. Wang ,&nbsp;Y.S. Jun ,&nbsp;D.A. Fike","doi":"10.1016/j.apgeochem.2025.106512","DOIUrl":"10.1016/j.apgeochem.2025.106512","url":null,"abstract":"<div><div>Simultaneous critical element recovery and ex-situ carbon mineralization of low-grade ultramafic deposits have garnered increasing interest. Understanding the selectivity of metal complexing organic ligands for various divalent metals present in ultramafic rocks during carbonate mineralization is required to optimize this process. Here we evaluate 2-amino-2-(hydroxymethyl)-1,3-propanediol (i.e., Tris) as a model for bidentate ligands that bind divalent metals with both amine and alcohol groups in alkaline conditions (pH 8–10.5) at 25 °C and 80 °C in carbonate-buffered solutions. Protonated Tris forms a stronger complex with metal ions and is selective for trace metals with Ni(II) &gt; Co(II) &gt; Fe(II) during carbonate precipitation, with the rates decreasing but selectivity increasing at lower temperature and lower pH. At 25 °C, metastable amorphous hydrated carbonates form, regardless of the amount of Tris present or pH values. At 80 °C and pH 8, the Co and Fe carbonates that form are a mixture of rosasite-group minerals (Co₂CO₃(OH)₂(H₂O) and Fe₂CO₃(OH)₂) and pure carbonates (sphaerocobaltite: CoCO₃ and siderite: FeCO₃), with the latter more stabilized with increasing Tris concentration. In mixed metal solutions without Tris at 25 °C where Fe:Ni or Fe:Co is 2:1, Fe increases the rates of Ni or Co carbonate precipitation. However, with increasing Tris concentration the presence of Ni or Co inhibits Fe carbonate precipitation. At 80 °C without Tris, Ni or Co substitute into the iron chukanovite (Fe₂CO₃(OH)₂) lattice, increasing Ni or Co carbonate precipitation rates. Increasing Tris concentration only slightly inhibits Fe and Co precipitation, but slows Ni precipitation up to 10 times, with Fe progressively partitioning into more pure carbonate phases with distinct crystalline morphologies. These findings suggest bidentate amine-bearing ligands may be effective at Ni and Co recovery during carbon mineralization of Fe-bearing ultramafic deposits at relatively low temperatures and slightly alkaline pH.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106512"},"PeriodicalIF":3.4,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144779865","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":"Geochemical associations of metals in corrosion scales from lead and copper drinking water pipes: Assessing the dissolution and bioaccessibility potentials","authors":"Benjamin F. Swaringen ,&nbsp;Juliana Matiz ,&nbsp;Kelly Milbrandt ,&nbsp;David A. Cornwell ,&nbsp;George D. Kamenov ,&nbsp;Jean-Claude J. Bonzongo","doi":"10.1016/j.apgeochem.2025.106506","DOIUrl":"10.1016/j.apgeochem.2025.106506","url":null,"abstract":"<div><div>This study investigated the speciation of metals accumulated in corrosion scales within drinking water distribution pipes by comparing two methods: X-ray diffraction (XRD) and an operationally defined chemical sequential extraction technique. Additionally, two single-step chemical extraction methods were employed to target metal fractions that are considered potentially bio-accessible if scale particulates are ingested through tap water consumption. The first is a 1.0 M CH₃COONa solution adjusted to pH 5 with CH₃COOH to target metal fractions operationally defined as exchangeable and bound to carbonate minerals. The second is a solution mimicking gastric juice (USEPA Method 1340). The corrosion scales analyzed were obtained from lead (Pb) and copper (Cu) drinking water pipes excavated from U.S. municipalities, where the metal concentrations released into the water are expected to meet the thresholds established by the Lead and Copper Rule (LCR). Although the amorphous phases were not detectable by XRD, our findings highlighted their potential contribution to the measured concentrations of dissolved metals, as inferred from the high concentrations of chemically extracted metals that were not associated with the minerals identified in the diffractograms. Therefore, identifying crystalline minerals using XRD alone is insufficient for predicting the potential of corrosion scales to contaminate potable water flowing through municipal distribution pipes with metals that pose human health risks. The assessment of potentially bio-accessible metal fractions showed that for Pb, Cu, and to some extent zinc (Zn), extraction with CH₃COONa resulted in dissolved metal concentration trends similar to those obtained with the US-EPA Method 1340, although the correlations were not strong. Overall, the US-EPA Method 1340 dissolved significantly higher amounts of Pb, Cu, Mn, Fe, Cr, and Sn compared to the CH₃COONa method, suggesting that these methods, if assumed acceptable for predicting the pool of bio-accessible metals, cannot be used interchangeably for corrosion scales.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106506"},"PeriodicalIF":3.4,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830188","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}