U. Geymond , K. Loiseau , V. Roche , G. Pasquet , S. Revillon , M. Sougrati , I. Moretti
{"title":"Mössbauer光谱学:量化生成h2的岩石中铁的形态和分布的关键工具","authors":"U. Geymond , K. Loiseau , V. Roche , G. Pasquet , S. Revillon , M. Sougrati , I. Moretti","doi":"10.1016/j.apgeochem.2025.106399","DOIUrl":null,"url":null,"abstract":"<div><div>Oxidation of Fe<sup>2+</sup> by anoxic water in the subsurface is a key geochemical process, contributing to the formation of natural dihydrogen (H<sub>2</sub>). The development and application of effective tools to accurately characterize the content and speciation of iron in samples is thus a major concern for H<sub>2</sub> prospection. Traditionally, the study of iron has been conducted through either time-consuming analyses at the micrometer scale or faster analyses at the bulk rock scale, raising concerns about the accuracy and representativeness of the characterization depending on the chosen approach. Moreover, most techniques are typically limited to determining either Fe distribution or Fe speciation, thus necessitating a full series of analyses to reach a comprehensive understanding of the sample. This approach does not align with the need for rapid and numerous characterizations required in H<sub>2</sub> prospection programs. In this study, we investigated the relevance of using Mössbauer Spectroscopy (MS) on complex mineral assemblage, by characterizing five Fe-rich natural samples. Among others, we conclude, based on the quality of the resulting spectra fitting that room-temperature (295K) data collection is more effective than low-temperature (6K) data collection, due to the challenges in deconvoluting the complex spectra of mixed mineral assemblages at low temperature. Fe<sup>2+</sup>/ΣFe ratios obtained from MS are compared with those derived from conventional Fe<sup>2+</sup> titration on the same samples. The comparison shows a great correlation between MS and titration results with an average deviation of 0.04 on the Fe<sup>2+</sup>/ΣFe ratio. This confirms the reliability of MS, providing at the same time insights into both Fe distribution (i.e., Fe mineralogy) and Fe speciation, contrary to titration that only gives access to bulk Fe<sup>2+</sup>/ΣFe ratio. Finally, results show that the accuracy of MS spectra fitting is significantly influenced by prior knowledge of the sample mineralogy, which can be easily leveraged by rapid and routinely performed characterization techniques (e.g., multispectral mineral imaging).</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"187 ","pages":"Article 106399"},"PeriodicalIF":3.1000,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Mössbauer spectroscopy: a key tool to quantify Fe-speciation and distribution in H2-generating rocks\",\"authors\":\"U. Geymond , K. Loiseau , V. Roche , G. Pasquet , S. Revillon , M. Sougrati , I. Moretti\",\"doi\":\"10.1016/j.apgeochem.2025.106399\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Oxidation of Fe<sup>2+</sup> by anoxic water in the subsurface is a key geochemical process, contributing to the formation of natural dihydrogen (H<sub>2</sub>). The development and application of effective tools to accurately characterize the content and speciation of iron in samples is thus a major concern for H<sub>2</sub> prospection. Traditionally, the study of iron has been conducted through either time-consuming analyses at the micrometer scale or faster analyses at the bulk rock scale, raising concerns about the accuracy and representativeness of the characterization depending on the chosen approach. Moreover, most techniques are typically limited to determining either Fe distribution or Fe speciation, thus necessitating a full series of analyses to reach a comprehensive understanding of the sample. This approach does not align with the need for rapid and numerous characterizations required in H<sub>2</sub> prospection programs. In this study, we investigated the relevance of using Mössbauer Spectroscopy (MS) on complex mineral assemblage, by characterizing five Fe-rich natural samples. Among others, we conclude, based on the quality of the resulting spectra fitting that room-temperature (295K) data collection is more effective than low-temperature (6K) data collection, due to the challenges in deconvoluting the complex spectra of mixed mineral assemblages at low temperature. Fe<sup>2+</sup>/ΣFe ratios obtained from MS are compared with those derived from conventional Fe<sup>2+</sup> titration on the same samples. The comparison shows a great correlation between MS and titration results with an average deviation of 0.04 on the Fe<sup>2+</sup>/ΣFe ratio. This confirms the reliability of MS, providing at the same time insights into both Fe distribution (i.e., Fe mineralogy) and Fe speciation, contrary to titration that only gives access to bulk Fe<sup>2+</sup>/ΣFe ratio. Finally, results show that the accuracy of MS spectra fitting is significantly influenced by prior knowledge of the sample mineralogy, which can be easily leveraged by rapid and routinely performed characterization techniques (e.g., multispectral mineral imaging).</div></div>\",\"PeriodicalId\":8064,\"journal\":{\"name\":\"Applied Geochemistry\",\"volume\":\"187 \",\"pages\":\"Article 106399\"},\"PeriodicalIF\":3.1000,\"publicationDate\":\"2025-04-23\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Applied Geochemistry\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0883292725001222\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Applied Geochemistry","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0883292725001222","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Mössbauer spectroscopy: a key tool to quantify Fe-speciation and distribution in H2-generating rocks
Oxidation of Fe2+ by anoxic water in the subsurface is a key geochemical process, contributing to the formation of natural dihydrogen (H2). The development and application of effective tools to accurately characterize the content and speciation of iron in samples is thus a major concern for H2 prospection. Traditionally, the study of iron has been conducted through either time-consuming analyses at the micrometer scale or faster analyses at the bulk rock scale, raising concerns about the accuracy and representativeness of the characterization depending on the chosen approach. Moreover, most techniques are typically limited to determining either Fe distribution or Fe speciation, thus necessitating a full series of analyses to reach a comprehensive understanding of the sample. This approach does not align with the need for rapid and numerous characterizations required in H2 prospection programs. In this study, we investigated the relevance of using Mössbauer Spectroscopy (MS) on complex mineral assemblage, by characterizing five Fe-rich natural samples. Among others, we conclude, based on the quality of the resulting spectra fitting that room-temperature (295K) data collection is more effective than low-temperature (6K) data collection, due to the challenges in deconvoluting the complex spectra of mixed mineral assemblages at low temperature. Fe2+/ΣFe ratios obtained from MS are compared with those derived from conventional Fe2+ titration on the same samples. The comparison shows a great correlation between MS and titration results with an average deviation of 0.04 on the Fe2+/ΣFe ratio. This confirms the reliability of MS, providing at the same time insights into both Fe distribution (i.e., Fe mineralogy) and Fe speciation, contrary to titration that only gives access to bulk Fe2+/ΣFe ratio. Finally, results show that the accuracy of MS spectra fitting is significantly influenced by prior knowledge of the sample mineralogy, which can be easily leveraged by rapid and routinely performed characterization techniques (e.g., multispectral mineral imaging).
期刊介绍:
Applied Geochemistry is an international journal devoted to publication of original research papers, rapid research communications and selected review papers in geochemistry and urban geochemistry which have some practical application to an aspect of human endeavour, such as the preservation of the environment, health, waste disposal and the search for resources. Papers on applications of inorganic, organic and isotope geochemistry and geochemical processes are therefore welcome provided they meet the main criterion. Spatial and temporal monitoring case studies are only of interest to our international readership if they present new ideas of broad application.
Topics covered include: (1) Environmental geochemistry (including natural and anthropogenic aspects, and protection and remediation strategies); (2) Hydrogeochemistry (surface and groundwater); (3) Medical (urban) geochemistry; (4) The search for energy resources (in particular unconventional oil and gas or emerging metal resources); (5) Energy exploitation (in particular geothermal energy and CCS); (6) Upgrading of energy and mineral resources where there is a direct geochemical application; and (7) Waste disposal, including nuclear waste disposal.