Pub Date : 2025-02-01DOI: 10.1016/j.apgeochem.2024.106271
Tullia Calogiuri , Iris Janssens , Alix Vidal , Jan Willem Van Groenigen , Tim Verdonck , Thomas Corbett , Jens Hartmann , Anna Neubeck , Harun Niron , Reinaldy P. Poetra , Lukas Rieder , Thomas Servotte , Abhijeet Singh , Michiel Van Tendeloo , Siegfried E. Vlaeminck , Sara Vicca , Mathilde Hagens
<div><div>To slow the rise in atmospheric carbon dioxide concentrations, Enhanced Silicate Weathering is emerging as a potentially significant Carbon Dioxide Removal technology. However, the biotic controls on rock weathering are not well understood, particularly for key soil faunal groups such as earthworms. Earthworms have shown to possibly enhance weathering, highlighting their potential to be introduced in controlled or engineered settings, such as reactors, to increase carbon sequestration. Here, we determined the potential for earthworms to thrive and to increase weathering rates in an artificial organo-mineral system simulating a bioreactor. We used two earthworm species (<em>Aporrectodea caliginosa</em> [Savigny] and <em>Allolobophora chlorotica</em> [Savigny]) at four densities (10, 20, 25 and 30 earthworms kg<sup>−1</sup> organo-mineral mixture), four silicate rock types (two basanites, dunite and diabase) of two to three grain sizes (d50 between 0.026 and 1.536 mm), two sources of organic materials (straw and co-digestate), two amounts of biochar (0 and 100 g kg<sup>−1</sup> organo-mineral mixture) and/or enzyme additions (laccase, urease and carbonic anhydrase at 20, 177 and 1955 units kg<sup>−1</sup> organo-mineral mixture, respectively), three water irrigation rates (125, 250 and 375 mL day<sup>−1</sup> kg<sup>−1</sup> organo-mineral mixture) and three watering frequencies (one, two and five times day<sup>−1</sup>). The experiment was conducted in eight rounds, each one lasting eight weeks, yielding data for a total of 323 experimental units. We measured earthworm survival and activity, as well as several commonly used weathering indicators in the organo-mineral mixture and in the leachate, as total alkalinity, inorganic carbon, pH, electrical conductivity and major cations. Using random forest regression, we found that earthworm survival and activity mainly depended on variables influencing the structure and drainage potential of the organo-mineral mixture, such as the presence of straw and increasing percentages of coarse grain sizes. Furthermore, we concluded that the effect of earthworms on weathering indicators depended on whether they survived or died by the end of the experimental period. Surviving earthworms had a neutral or negative effect on weathering indicators, likely because the experimental duration was too short to detect an increase in inorganic carbon, or because there was an increase in organic rather than inorganic carbon in the organo-mineral mixture. In contrast, dead earthworms enhanced almost all weathering indicators considered, suggesting that microbial processes associated with decomposing earthworm bodies may play a role in enhancing weathering. Our results also emphasize that the role of earthworms in Enhanced Silicate Weathering within bioreactors might be overestimated if weathering indicators exclusively rely on changes in mineralogy and ions release to quantify earthworm effects on carbon sequestrati
{"title":"How earthworms thrive and drive silicate rock weathering in an artificial organo-mineral system","authors":"Tullia Calogiuri , Iris Janssens , Alix Vidal , Jan Willem Van Groenigen , Tim Verdonck , Thomas Corbett , Jens Hartmann , Anna Neubeck , Harun Niron , Reinaldy P. Poetra , Lukas Rieder , Thomas Servotte , Abhijeet Singh , Michiel Van Tendeloo , Siegfried E. Vlaeminck , Sara Vicca , Mathilde Hagens","doi":"10.1016/j.apgeochem.2024.106271","DOIUrl":"10.1016/j.apgeochem.2024.106271","url":null,"abstract":"<div><div>To slow the rise in atmospheric carbon dioxide concentrations, Enhanced Silicate Weathering is emerging as a potentially significant Carbon Dioxide Removal technology. However, the biotic controls on rock weathering are not well understood, particularly for key soil faunal groups such as earthworms. Earthworms have shown to possibly enhance weathering, highlighting their potential to be introduced in controlled or engineered settings, such as reactors, to increase carbon sequestration. Here, we determined the potential for earthworms to thrive and to increase weathering rates in an artificial organo-mineral system simulating a bioreactor. We used two earthworm species (<em>Aporrectodea caliginosa</em> [Savigny] and <em>Allolobophora chlorotica</em> [Savigny]) at four densities (10, 20, 25 and 30 earthworms kg<sup>−1</sup> organo-mineral mixture), four silicate rock types (two basanites, dunite and diabase) of two to three grain sizes (d50 between 0.026 and 1.536 mm), two sources of organic materials (straw and co-digestate), two amounts of biochar (0 and 100 g kg<sup>−1</sup> organo-mineral mixture) and/or enzyme additions (laccase, urease and carbonic anhydrase at 20, 177 and 1955 units kg<sup>−1</sup> organo-mineral mixture, respectively), three water irrigation rates (125, 250 and 375 mL day<sup>−1</sup> kg<sup>−1</sup> organo-mineral mixture) and three watering frequencies (one, two and five times day<sup>−1</sup>). The experiment was conducted in eight rounds, each one lasting eight weeks, yielding data for a total of 323 experimental units. We measured earthworm survival and activity, as well as several commonly used weathering indicators in the organo-mineral mixture and in the leachate, as total alkalinity, inorganic carbon, pH, electrical conductivity and major cations. Using random forest regression, we found that earthworm survival and activity mainly depended on variables influencing the structure and drainage potential of the organo-mineral mixture, such as the presence of straw and increasing percentages of coarse grain sizes. Furthermore, we concluded that the effect of earthworms on weathering indicators depended on whether they survived or died by the end of the experimental period. Surviving earthworms had a neutral or negative effect on weathering indicators, likely because the experimental duration was too short to detect an increase in inorganic carbon, or because there was an increase in organic rather than inorganic carbon in the organo-mineral mixture. In contrast, dead earthworms enhanced almost all weathering indicators considered, suggesting that microbial processes associated with decomposing earthworm bodies may play a role in enhancing weathering. Our results also emphasize that the role of earthworms in Enhanced Silicate Weathering within bioreactors might be overestimated if weathering indicators exclusively rely on changes in mineralogy and ions release to quantify earthworm effects on carbon sequestrati","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106271"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177914","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}
Pub Date : 2025-02-01DOI: 10.1016/j.apgeochem.2025.106312
Dimitra Zerva , Martin A. Glaus , John L. Provis , Sergey V. Churakov
Surface diffusion of cationic species has frequently been postulated to explain the results of diffusion studies in compacted clay minerals and clay rocks. However, the underlying mechanism of this process is not well understood, and the factors controlling the diffusive flux are not yet satisfactorily quantified. In this study, the role of ion-specific molecular interactions in the electric double layer formed at the clay mineral-fluid interface is investigated, particularly their effect on the diffusive transport of 57Co2+ and 65Zn2+ tracers. To this end, in-diffusion experiments were conducted at different background electrolyte concentrations in compacted illite with Li+, Na+, K+ and Cs+ forms. The alkali cations in this series have decreasing hydration enthalpy () and an increasing effective hydrated ion radius. The diffusion data were interpreted using the “two site protolysis non electrostatic surface complexation/electrical double layer” (2SPNE SC/EDL) model. The diffusion and sorption behaviour of 57Co2+ and 65Zn2+ in various background electrolyte concentrations and homoionic forms of illite was compared in terms of the effective diffusion coefficient De and the sorption distribution coefficient Rd. The extent of surface diffusion was assessed via surface diffusion ratio (φ). The results suggest that of ions is a critical factor controlling surface charge neutralisation, and consequently the distribution of the mobile species between the diffuse layer near the mineral surface and the bulk-like water in macroscopic pores. Although 65Zn2+ has higher Rd values compared to 57Co2+, the surface diffusion phenomenon is equally relevant for both tracers studied in this work. For the 0.03 M and 0.1 M background electrolytes, φ follows the order , while in 0.5 M electrolyte solution the contribution of surface diffusion is negligible in most of the homocationic forms.
{"title":"Diffusion and retention of Co2+ and Zn2+ in compacted homocationic forms of illite: Role of the electrical double layer","authors":"Dimitra Zerva , Martin A. Glaus , John L. Provis , Sergey V. Churakov","doi":"10.1016/j.apgeochem.2025.106312","DOIUrl":"10.1016/j.apgeochem.2025.106312","url":null,"abstract":"<div><div>Surface diffusion of cationic species has frequently been postulated to explain the results of diffusion studies in compacted clay minerals and clay rocks. However, the underlying mechanism of this process is not well understood, and the factors controlling the diffusive flux are not yet satisfactorily quantified. In this study, the role of ion-specific molecular interactions in the electric double layer formed at the clay mineral-fluid interface is investigated, particularly their effect on the diffusive transport of <sup>57</sup>Co<sup>2+</sup> and <sup>65</sup>Zn<sup>2+</sup> tracers. To this end, in-diffusion experiments were conducted at different background electrolyte concentrations in compacted illite with Li<sup>+</sup>, Na<sup>+</sup>, K<sup>+</sup> and Cs<sup>+</sup> forms. The alkali cations in this series have decreasing hydration enthalpy (<span><math><mrow><msub><mrow><mo>Δ</mo><mi>H</mi></mrow><mrow><mi>h</mi><mi>y</mi><mi>d</mi></mrow></msub></mrow></math></span>) and an increasing effective hydrated ion radius. The diffusion data were interpreted using the “two site protolysis non electrostatic surface complexation/electrical double layer” (2SPNE SC/EDL) model. The diffusion and sorption behaviour of <sup>57</sup>Co<sup>2+</sup> and <sup>65</sup>Zn<sup>2+</sup> in various background electrolyte concentrations and homoionic forms of illite was compared in terms of the effective diffusion coefficient <em>D</em><sub><em>e</em></sub> and the sorption distribution coefficient <em>R</em><sub><em>d</em></sub>. The extent of surface diffusion was assessed via surface diffusion ratio (<em>φ</em>). The results suggest that <span><math><mrow><msub><mrow><mo>Δ</mo><mi>H</mi></mrow><mrow><mi>h</mi><mi>y</mi><mi>d</mi></mrow></msub></mrow></math></span> of ions is a critical factor controlling surface charge neutralisation, and consequently the distribution of the mobile species between the diffuse layer near the mineral surface and the bulk-like water in macroscopic pores. Although <sup>65</sup>Zn<sup>2+</sup> has higher <em>R</em><sub><em>d</em></sub> values compared to <sup>57</sup>Co<sup>2+</sup>, the surface diffusion phenomenon is equally relevant for both tracers studied in this work. For the 0.03 M and 0.1 M background electrolytes, <em>φ</em> follows the order <span><math><mrow><mi>L</mi><mi>i</mi><mo>≈</mo><mi>N</mi><mi>a</mi><mo>></mo><mi>K</mi><mo>></mo><mi>C</mi><mi>s</mi></mrow></math></span>, while in 0.5 M electrolyte solution the contribution of surface diffusion is negligible in most of the homocationic forms.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"181 ","pages":"Article 106312"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428959","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}
Pub Date : 2025-02-01DOI: 10.1016/j.apgeochem.2025.106297
Qinghua Li , Yaojin Xiong , Yamin Deng , Yiqun Gan , Yao Du
Groundwater ammonium (NH4+) contamination can threaten human health and disrupt surface ecological balance. Although the sources and fate of NH4+-N in groundwater have been widely studied, comparative research on this issue between different large basins under contrasting sediment sources and hydrogeological structures is weak. In this study, we used a combination of water chemistry, stable isotopes (H/O/C/N), excitation-emission-matrix spectra and 16 S rRNA gene sequencing to reveal the differences in the sources and fate of NH4+-N in groundwater between Poyang Lake Plain (PYP) and Dongting Lake Plain (DTP), two large alluvial-lacustrine plains in central Yangtze River. The results showed that NH4+-N in DTP groundwater occurred in a more closed and reduced environment, with stronger water-rock interaction and richer organic matter compared to that in PYP groundwater. NH4+-N in DTP groundwater mainly originates from the intensive degradation of organic matter up to methanogenic stage, while NH4+-N in PYP groundwater is affected by the coupled influence of organic matter fermentation before the methanogenic stage and anthropogenic activities. In addition, the specific hydrogeochemical environment in PYP groundwater is favorable to the natural removal of NH4+-N caused by processes such as anammox and Feammox. The sediment provenance and hydrogeological structure of the two large plains are the key factors determing the contrasting sources and fate of NH4+-N in groundwater.
{"title":"Contrasting sources and fate of ammonium in groundwater systems of two large alluvial-lacustrine basins","authors":"Qinghua Li , Yaojin Xiong , Yamin Deng , Yiqun Gan , Yao Du","doi":"10.1016/j.apgeochem.2025.106297","DOIUrl":"10.1016/j.apgeochem.2025.106297","url":null,"abstract":"<div><div>Groundwater ammonium (NH<sub>4</sub><sup>+</sup>) contamination can threaten human health and disrupt surface ecological balance. Although the sources and fate of NH<sub>4</sub><sup>+</sup>-N in groundwater have been widely studied, comparative research on this issue between different large basins under contrasting sediment sources and hydrogeological structures is weak. In this study, we used a combination of water chemistry, stable isotopes (H/O/C/N), excitation-emission-matrix spectra and 16 S rRNA gene sequencing to reveal the differences in the sources and fate of NH<sub>4</sub><sup>+</sup>-N in groundwater between Poyang Lake Plain (PYP) and Dongting Lake Plain (DTP), two large alluvial-lacustrine plains in central Yangtze River. The results showed that NH<sub>4</sub><sup>+</sup>-N in DTP groundwater occurred in a more closed and reduced environment, with stronger water-rock interaction and richer organic matter compared to that in PYP groundwater. NH<sub>4</sub><sup>+</sup>-N in DTP groundwater mainly originates from the intensive degradation of organic matter up to methanogenic stage, while NH<sub>4</sub><sup>+</sup>-N in PYP groundwater is affected by the coupled influence of organic matter fermentation before the methanogenic stage and anthropogenic activities. In addition, the specific hydrogeochemical environment in PYP groundwater is favorable to the natural removal of NH<sub>4</sub><sup>+</sup>-N caused by processes such as anammox and Feammox. The sediment provenance and hydrogeological structure of the two large plains are the key factors determing the contrasting sources and fate of NH<sub>4</sub><sup>+</sup>-N in groundwater.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106297"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.apgeochem.2025.106295
Milad Ezzati , Yves Gélinas
Coastal shelves significantly contribute to the burial of natural organic matter (NOM) in marine sediments, with about 21.5 ± 8.6% of NOM associated with reactive iron oxides, which preserve NOM from biodegradation. Quantifying this preserved NOM requires a method to release bound carbonaceous molecules from iron minerals. The citrate-bicarbonate-dithionate (CBD) method is commonly used to liberate NOM from iron oxides through reductive dissolution. This method includes a control experiment using an NaCl solution to distinguish NOM associated with iron oxides from that leaching out from other minerals. This study aims to determine if desorbed NOM during the control experiment comes from other minerals or is loosely bound to iron oxides. We synthesized lepidocrocite (γ-FeOOH) in the presence and absence of plankton-extracted NOM to mimic sorption and conducted similar experiments on kaolinite, montmorillonite, and their mixture, representing common clay minerals in sediments. Quantifying the carbon content revealed that NOM associated with γ-FeOOH is 1.5–9.0 times greater than with other minerals. Post-treatment results indicate a 22.2%–42.7% loss of NOM associated with iron oxides, suggesting that deducting NOM lost during the control step underestimates the amount of carbon preserved by iron minerals in marine sediments.
沿海陆架对海洋沉积物中天然有机物（NOM）的埋藏起了重要作用，约 21.5 ± 8.6% 的天然有机物与活性氧化铁有关，活性氧化铁可使天然有机物免于生物降解。要量化这些保存下来的 NOM，需要一种从铁矿物中释放出结合碳质分子的方法。柠檬酸盐-碳酸氢盐-二硫酸盐（CBD）法通常用于通过还原溶解从氧化铁中释放 NOM。该方法包括一个使用氯化钠溶液的对照实验，以区分与铁氧化物相关的 NOM 和从其他矿物中沥滤出的 NOM。本研究旨在确定对照实验中脱附的 NOM 是来自其他矿物还是与铁氧化物松散结合。我们在浮游生物提取的 NOM 存在和不存在的情况下合成了鳞片铁氧体（γ-FeOOH）来模拟吸附，并对高岭石、蒙脱石及其混合物（代表沉积物中常见的粘土矿物）进行了类似的实验。对碳含量进行量化后发现，与 γ-FeOOH 相关的 NOM 是其他矿物的 1.5-9.0 倍。后处理结果表明，与铁氧化物相关的 NOM 损失了 22.2%-42.7%，这表明扣除控制步骤中损失的 NOM 会低估海洋沉积物中铁矿物保存的碳量。
{"title":"A methodological study on the analysis of organic matter associated with iron oxides in marine sediments","authors":"Milad Ezzati , Yves Gélinas","doi":"10.1016/j.apgeochem.2025.106295","DOIUrl":"10.1016/j.apgeochem.2025.106295","url":null,"abstract":"<div><div>Coastal shelves significantly contribute to the burial of natural organic matter (NOM) in marine sediments, with about 21.5 ± 8.6% of NOM associated with reactive iron oxides, which preserve NOM from biodegradation. Quantifying this preserved NOM requires a method to release bound carbonaceous molecules from iron minerals. The citrate-bicarbonate-dithionate (CBD) method is commonly used to liberate NOM from iron oxides through reductive dissolution. This method includes a control experiment using an NaCl solution to distinguish NOM associated with iron oxides from that leaching out from other minerals. This study aims to determine if desorbed NOM during the control experiment comes from other minerals or is loosely bound to iron oxides. We synthesized lepidocrocite (γ-FeOOH) in the presence and absence of plankton-extracted NOM to mimic sorption and conducted similar experiments on kaolinite, montmorillonite, and their mixture, representing common clay minerals in sediments. Quantifying the carbon content revealed that NOM associated with γ-FeOOH is 1.5–9.0 times greater than with other minerals. Post-treatment results indicate a 22.2%–42.7% loss of NOM associated with iron oxides, suggesting that deducting NOM lost during the control step underestimates the amount of carbon preserved by iron minerals in marine sediments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106295"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178831","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}
Pub Date : 2025-02-01DOI: 10.1016/j.apgeochem.2024.106257
Qian Zhang , Zhijun Jin , Ende Deng , Zaigang Xu , Rukai Zhu , Quanyou Liu , Zhihua Yan , Ke Hu , Tianyu Zheng , Zhazha Hu
Compared with fully marine and lacustrine shales, coal-bearing analogues have been rarely investigated. This study attempts to deepen our insights into the provenance, deposition, maturity and organic matter pores (OMPs) of coal-bearing shales based on detailed organic geochemical and petrographic analysis of a profile of the Longtan Formation (LTF) at Tucheng Syncline, Southwestern Guizhou, China.
Our results showed that the overall total organic carbon (TOC) contents are high (15.51 wt% on average), generally larger than 2 wt% with some coal samples reaching up to 69.5 wt%. Macro- and microscopic observations suggested that terrestrial higher plant-derived macerals make up a predominant proportion to total organic matter, while quantitative analysis based on maceral counting and organic geochemistry revealed a large percentage of aquatic-derived organic matter in the LTF. The aquatic-derived organic matter is expected to affect the empirical relation between vitrinite reflectance (VRr) and Rock-Eval Tmax by showing a divergent regression line compared to that of the type III kerogen. Based on the pore morphology and the outline of dispersed organic matter, OMPs either show sharp edges in discernible terrestrial organic matter or bubble shapes in indistinct aquatic-derived organic matter. VRr and Tmax values range from 1.19 to 1.84 %VRr (the mean value is 1.48%VRr) and from 455 to 497 °C (469 °C on average precluding one anomalously high value of 555 °C), respectively. At this level of maturity, hydrocarbons have been generated in large quantities given the high organic matter content of the studied samples. Compared to the successful shale gas plays, e.g., the Barnett Shale and the Longmaxi Shale, the Longtan Shale (LTS) also shows good potential given its much larger thickness and TOC, appropriate thermal maturity. Nevertheless, cautious should be taken considering its smaller porosity and quartz content, which affect the storage capacity and the fracability of the LTS. This study contributes to a better understanding of the accumulation and maturation conditions of organic matter in coal-bearing shales.
{"title":"Accumulation and maturation of organic matter in shales: The coal-bearing Permian Longtan Formation at Tucheng Syncline, Southwestern Guizhou, China","authors":"Qian Zhang , Zhijun Jin , Ende Deng , Zaigang Xu , Rukai Zhu , Quanyou Liu , Zhihua Yan , Ke Hu , Tianyu Zheng , Zhazha Hu","doi":"10.1016/j.apgeochem.2024.106257","DOIUrl":"10.1016/j.apgeochem.2024.106257","url":null,"abstract":"<div><div>Compared with fully marine and lacustrine shales, coal-bearing analogues have been rarely investigated. This study attempts to deepen our insights into the provenance, deposition, maturity and organic matter pores (OMPs) of coal-bearing shales based on detailed organic geochemical and petrographic analysis of a profile of the Longtan Formation (LTF) at Tucheng Syncline, Southwestern Guizhou, China.</div><div>Our results showed that the overall total organic carbon (TOC) contents are high (15.51 wt% on average), generally larger than 2 wt% with some coal samples reaching up to 69.5 wt%. Macro- and microscopic observations suggested that terrestrial higher plant-derived macerals make up a predominant proportion to total organic matter, while quantitative analysis based on maceral counting and organic geochemistry revealed a large percentage of aquatic-derived organic matter in the LTF. The aquatic-derived organic matter is expected to affect the empirical relation between vitrinite reflectance (VR<sub>r</sub>) and Rock-Eval T<sub>max</sub> by showing a divergent regression line compared to that of the type III kerogen. Based on the pore morphology and the outline of dispersed organic matter, OMPs either show sharp edges in discernible terrestrial organic matter or bubble shapes in indistinct aquatic-derived organic matter. VR<sub>r</sub> and T<sub>max</sub> values range from 1.19 to 1.84 %VR<sub>r</sub> (the mean value is 1.48%VR<sub>r</sub>) and from 455 to 497 °C (469 °C on average precluding one anomalously high value of 555 °C), respectively. At this level of maturity, hydrocarbons have been generated in large quantities given the high organic matter content of the studied samples. Compared to the successful shale gas plays, e.g., the Barnett Shale and the Longmaxi Shale, the Longtan Shale (LTS) also shows good potential given its much larger thickness and TOC, appropriate thermal maturity. Nevertheless, cautious should be taken considering its smaller porosity and quartz content, which affect the storage capacity and the fracability of the LTS. This study contributes to a better understanding of the accumulation and maturation conditions of organic matter in coal-bearing shales.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106257"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.apgeochem.2025.106293
Colleen Atherton , David Wilson , Steven P. Holland , Katherine E. Raymond , David R. Barsi , Jordan Zak , Leslie Smith , David C. Sego , Richard T. Amos , Dogan Paktunc , Carol J. Ptacek , David W. Blowes
Deconstruction of a 15 m high low-sulfide (0.035 wt% S) experimental waste-rock pile was conducted to obtain a dense, spatially located sample set for characterization of the solid-phase mineralogy, microbiological community composition, and pore-water geochemistry. The experimental test pile, located in northern Canada, was deconstructed 8 years after construction. Pore-water with low pH was generally associated with elevated concentrations of SO4 and dissolved metals. Regions of differing pH were present within the test pile, indicating heterogeneous distribution of sulfide and carbonate minerals. Most probable number analysis showed that neutrophilic sulfur oxidizing bacteria were the most consistently prolific of populations associated with acid mine drainage at the time of deconstruction. The mineralogical evolution was examined through comparison of unweathered samples collected at the time of pile construction to weathered samples collected during the deconstruction phase. This analysis indicated that the C content of the waste rock was depleted, but the total S content of the waste rock remained relatively unchanged. Neutralization potential ratios calculated using C and total S indicate that regions of low paste pH (as low as 4.0) were generally consistent with the presence of material classified as potentially acid generating or of uncertain acid generating potential. The deconstruction study shows that variable conditions exist within the test pile (e.g., sharp changes in pH over a few meters) suggesting that waste-rock heterogeneity has influenced the geochemical evolution of the pore water within the test pile.
{"title":"Diavik Waste Rock Project: Post-emplacement investigation of sulfide weathering from a deconstructed experimental waste-rock pile","authors":"Colleen Atherton , David Wilson , Steven P. Holland , Katherine E. Raymond , David R. Barsi , Jordan Zak , Leslie Smith , David C. Sego , Richard T. Amos , Dogan Paktunc , Carol J. Ptacek , David W. Blowes","doi":"10.1016/j.apgeochem.2025.106293","DOIUrl":"10.1016/j.apgeochem.2025.106293","url":null,"abstract":"<div><div>Deconstruction of a 15 m high low-sulfide (0.035 wt% S) experimental waste-rock pile was conducted to obtain a dense, spatially located sample set for characterization of the solid-phase mineralogy, microbiological community composition, and pore-water geochemistry. The experimental test pile, located in northern Canada, was deconstructed 8 years after construction. Pore-water with low pH was generally associated with elevated concentrations of SO<sub>4</sub> and dissolved metals. Regions of differing pH were present within the test pile, indicating heterogeneous distribution of sulfide and carbonate minerals. Most probable number analysis showed that neutrophilic sulfur oxidizing bacteria were the most consistently prolific of populations associated with acid mine drainage at the time of deconstruction. The mineralogical evolution was examined through comparison of unweathered samples collected at the time of pile construction to weathered samples collected during the deconstruction phase. This analysis indicated that the C content of the waste rock was depleted, but the total S content of the waste rock remained relatively unchanged. Neutralization potential ratios calculated using C and total S indicate that regions of low paste pH (as low as 4.0) were generally consistent with the presence of material classified as potentially acid generating or of uncertain acid generating potential. The deconstruction study shows that variable conditions exist within the test pile (e.g., sharp changes in pH over a few meters) suggesting that waste-rock heterogeneity has influenced the geochemical evolution of the pore water within the test pile.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"181 ","pages":"Article 106293"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419164","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}
The formation of gas hydrates in the permafrost zone of the Tibetan Plateau is complicated, so it is difficult to achieve significant breakthrough in gas hydrate exploration. In this paper, we compare the geochemical anomalies in different drill holes, with a view to elucidating their indicative roles in migration and accumulation of gas hydrate and hydrocarbon. The results demonstrate that the acidysis hydrocarbon and fluorescence spectra of the borehole in the discovered hydrate area show obvious enrichment characteristics, with significantly higher anomaly intensity than that in the borehole where no hydrate samples are found. The geochemical anomalies have obvious response characteristics with the cracks or fracture zones. The hydrocarbon genesis analysis indicates that the dominant cause is pyrolysis. The anomalies of acid hydrocarbon methane, methane carbon isotopes and fluorescence spectra can be used as indicators of natural gas hydrate and its transport and aggregation. The effective time and space configuration of the reservoir elements including gas source, migration and concentration, and permafrost conditions is crucial to the eventual formation of natural gas hydrate in the study region. The research can lay a foundation for future gas hydrate exploration in the Tibetan Plateau permafrost region.
{"title":"Geochemical characteristics of borehole cores and their indicative significance for gas hydrates in the permafrost area, Qinghai-Tibet Plateau","authors":"Yalong Zhou , Shunyao Zhang , Zhibin Yang , Fugui Zhang","doi":"10.1016/j.apgeochem.2024.106223","DOIUrl":"10.1016/j.apgeochem.2024.106223","url":null,"abstract":"<div><div>The formation of gas hydrates in the permafrost zone of the Tibetan Plateau is complicated, so it is difficult to achieve significant breakthrough in gas hydrate exploration. In this paper, we compare the geochemical anomalies in different drill holes, with a view to elucidating their indicative roles in migration and accumulation of gas hydrate and hydrocarbon. The results demonstrate that the acidysis hydrocarbon and fluorescence spectra of the borehole in the discovered hydrate area show obvious enrichment characteristics, with significantly higher anomaly intensity than that in the borehole where no hydrate samples are found. The geochemical anomalies have obvious response characteristics with the cracks or fracture zones. The hydrocarbon genesis analysis indicates that the dominant cause is pyrolysis. The anomalies of acid hydrocarbon methane, methane carbon isotopes and fluorescence spectra can be used as indicators of natural gas hydrate and its transport and aggregation. The effective time and space configuration of the reservoir elements including gas source, migration and concentration, and permafrost conditions is crucial to the eventual formation of natural gas hydrate in the study region. The research can lay a foundation for future gas hydrate exploration in the Tibetan Plateau permafrost region.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"178 ","pages":"Article 106223"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106253
Hudson Moraes Rocha , João Batista Pereira Cabral , Fernanda Luisa Ramalho , Assunção Andrade de Barcelos , Patrícia da Silva Gomes , Valter Antonio Becegato , Alexandre Tadeu Paulino
It is essential to know the level of radiation in the environment to develop and implement control programs to protect humans from exposure to high levels of contamination. As cerrado soils contain heavy metals and radionuclides in their composition due to agricultural activities, the objective of this study was to evaluate the concentrations and distributions of radionuclides such as potassium (40K), uranium (238U), and thorium (232Th) in the soils of the cerrado biome of the Bonito River drainage basin, and their relationship with the land occupation and use model. Gamma-ray spectrometric measurements were performed at 38 sampling points in this study. The highest three concentrations of radionuclides were detected at points 14, 16 and 32 for 238U (209.03, 221.35 and 224.28 Bq kg−1), at points 21, 20 and 32 for 232Th (133.53, 148.08 and 154.30 Bq kg−1), and at points 8, 32 and 13 for 40K (381.23, 470.75 and 698.93 Bq kg−1). In the analysis of variance at 5% probability level for the factors of rock lithology and particle size of the soils, the concentrations and distributions of the radionuclides were significant. The first component of the principal component analysis (PCA), and the basic cations calcium (Ca2+), magnesium (Mg2+) and potassium (K+) showed high correlation. It indicates the importance of cationic macronutrients in plant nutrition. The results of this study proved to be valuable for explaining and understanding the presence and distribution of 40K, 238U and 232Th in drainage basins on cerrado biomes in relation to the different natural and anthropogenic aspects of the landscape. In this sense, it was considered that clay-textured soils have higher chemical retention capacities of radioactive species. This could be useful for evaluating the radionuclide pollution in drainage basins of different regions around the world.
{"title":"Distribution of radionuclides in soils of drainage basin/cerrado biome and their relationship with the land occupation and use model","authors":"Hudson Moraes Rocha , João Batista Pereira Cabral , Fernanda Luisa Ramalho , Assunção Andrade de Barcelos , Patrícia da Silva Gomes , Valter Antonio Becegato , Alexandre Tadeu Paulino","doi":"10.1016/j.apgeochem.2024.106253","DOIUrl":"10.1016/j.apgeochem.2024.106253","url":null,"abstract":"<div><div>It is essential to know the level of radiation in the environment to develop and implement control programs to protect humans from exposure to high levels of contamination. As cerrado soils contain heavy metals and radionuclides in their composition due to agricultural activities, the objective of this study was to evaluate the concentrations and distributions of radionuclides such as potassium (<sup>40</sup>K), uranium (<sup>238</sup>U), and thorium (<sup>232</sup>Th) in the soils of the cerrado biome of the Bonito River drainage basin, and their relationship with the land occupation and use model. Gamma-ray spectrometric measurements were performed at 38 sampling points in this study. The highest three concentrations of radionuclides were detected at points 14, 16 and 32 for <sup>238</sup>U (209.03, 221.35 and 224.28 Bq kg<sup>−1</sup>), at points 21, 20 and 32 for <sup>232</sup>Th (133.53, 148.08 and 154.30 Bq kg<sup>−1</sup>), and at points 8, 32 and 13 for <sup>40</sup>K (381.23, 470.75 and 698.93 Bq kg<sup>−1</sup>). In the analysis of variance at 5% probability level for the factors of rock lithology and particle size of the soils, the concentrations and distributions of the radionuclides were significant. The first component of the principal component analysis (PCA), and the basic cations calcium (Ca<sup>2+</sup>), magnesium (Mg<sup>2+</sup>) and potassium (K<sup>+</sup>) showed high correlation. It indicates the importance of cationic macronutrients in plant nutrition. The results of this study proved to be valuable for explaining and understanding the presence and distribution of <sup>40</sup>K, <sup>238</sup>U and <sup>232</sup>Th in drainage basins on cerrado biomes in relation to the different natural and anthropogenic aspects of the landscape. In this sense, it was considered that clay-textured soils have higher chemical retention capacities of radioactive species. This could be useful for evaluating the radionuclide pollution in drainage basins of different regions around the world.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"179 ","pages":"Article 106253"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106256
E. Colàs , J. Rodríguez-Mestres , D. Pérez , R. Mas , P.F. dos Santos , D. García , L. Duro , W. Bower , S. Brassinnes , B. Madé
Results of a recent benchmarking exercise for the thermodynamic database ThermoChimie (www.thermochimie-tdb.com), focused on radionuclides and chemo-toxic elements, are described. This benchmarking is largely based on the comparison of calculated solubility and associated aqueous speciation in solutions representative of clay or cement porewaters. Those exercises help to check if the selected thermodynamic data are accurate and consistent and contribute to identify if all relevant aqueous species and solid phases are included in the database. The comparison has shown some specific cases for which estimations provide a useful tool to cover data gaps, especially those related to temperature effects. Also, it has highlighted that the possibility of improvement of some data sets is dependent on the availability of reliable and accurate experimental information.
{"title":"The ThermoChimie database: Comparison with other databases and example calculations for radionuclides and chemo-toxic elements","authors":"E. Colàs , J. Rodríguez-Mestres , D. Pérez , R. Mas , P.F. dos Santos , D. García , L. Duro , W. Bower , S. Brassinnes , B. Madé","doi":"10.1016/j.apgeochem.2024.106256","DOIUrl":"10.1016/j.apgeochem.2024.106256","url":null,"abstract":"<div><div>Results of a recent benchmarking exercise for the thermodynamic database ThermoChimie (<span><span>www.thermochimie-tdb.com</span><svg><path></path></svg></span>), focused on radionuclides and chemo-toxic elements, are described. This benchmarking is largely based on the comparison of calculated solubility and associated aqueous speciation in solutions representative of clay or cement porewaters. Those exercises help to check if the selected thermodynamic data are accurate and consistent and contribute to identify if all relevant aqueous species and solid phases are included in the database. The comparison has shown some specific cases for which estimations provide a useful tool to cover data gaps, especially those related to temperature effects. Also, it has highlighted that the possibility of improvement of some data sets is dependent on the availability of reliable and accurate experimental information.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"179 ","pages":"Article 106256"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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