Pub Date : 2025-02-01DOI: 10.1016/j.apgeochem.2025.106300
Qianting Ye , Pei Wang , Yuzhen Liang , Rong Li , Zhenqing Shi
Dissolved organic matter (DOM) is one of the most important ligands regulating the speciation and distribution of heavy metals (HMs) in natural environments. It is well accepted that individual DOM functional groups and binding sites play a pivotal role in controlling HM reactions with DOM in both equilibrium and kinetic aspects. Therefore, despite of the complexity of interactions between DOM and HMs, mechanistic models have been developed to quantify the reactions between HMs and DOM binding sites. This paper reviews the current status of modeling equilibrium and kinetics of HMs reactions with DOM, including (i) modeling the equilibrium binding of HMs to DOM, (ii) quantifying the influence of interactions between DOM and minerals on HM-DOM reactions, and (iii) modeling kinetics of HM complexation with and dissociation from DOM. Finally, we point out the limitations of current models and outline the future prospects for developing predictive models of HM-DOM reactions. We hope this review will provide helpful guidance for better understanding of the development and application of quantitative models for HM-DOM reactions in the environment.
{"title":"Modeling the equilibrium and kinetics of heavy metals reactions with dissolved organic matter","authors":"Qianting Ye , Pei Wang , Yuzhen Liang , Rong Li , Zhenqing Shi","doi":"10.1016/j.apgeochem.2025.106300","DOIUrl":"10.1016/j.apgeochem.2025.106300","url":null,"abstract":"<div><div>Dissolved organic matter (DOM) is one of the most important ligands regulating the speciation and distribution of heavy metals (HMs) in natural environments. It is well accepted that individual DOM functional groups and binding sites play a pivotal role in controlling HM reactions with DOM in both equilibrium and kinetic aspects. Therefore, despite of the complexity of interactions between DOM and HMs, mechanistic models have been developed to quantify the reactions between HMs and DOM binding sites. This paper reviews the current status of modeling equilibrium and kinetics of HMs reactions with DOM, including (i) modeling the equilibrium binding of HMs to DOM, (ii) quantifying the influence of interactions between DOM and minerals on HM-DOM reactions, and (iii) modeling kinetics of HM complexation with and dissociation from DOM. Finally, we point out the limitations of current models and outline the future prospects for developing predictive models of HM-DOM reactions. We hope this review will provide helpful guidance for better understanding of the development and application of quantitative models for HM-DOM reactions in the environment.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"181 ","pages":"Article 106300"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387222","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.2025.106301
Steve Lange , Matthew Isaacs , Martina Klinkenberg , David Read , Dirk Bosbach , Guido Deissmann
Iodine-129 (129I) is an important radionuclide in the context of nuclear waste disposal owing to its long half-life and potentially high mobility in the environment. The uptake of iodide and iodate by cement hydration phases, including calcium silicate hydrates (CSH), AFm and ettringite, as well as hardened cement paste made from Ordinary Portland cement, has been studied in batch-type sorption experiments to enhance understanding of iodine retention mechanisms in engineered repositories. Uptake kinetics were generally fast, leading to steady state within 30 days. Strong uptake of iodine by AFm and ettringite was observed, the mechanism dependent on the iodine speciation. Iodide is retained in both AFm and ettringite by exchange for sulphate, whereas with iodate, iodate-substituted ettringite is formed by phase transformation or ion exchange in the case of AFm and ettringite, respectively. The contribution of CSH phases to iodine retention in cementitious systems depends on the Ca/Si-ratio of the CSH and the alkalinity of the solution, with stronger retention in young hyperalkaline cementitious materials. These findings have implications when selecting grouts for the immobilisation of radioactive waste streams containing 129I or for choosing cementitious grouts and/or backfill materials in nuclear waste repositories.
{"title":"Uptake of iodine by cement hydration phases: Implications for radioactive waste disposal","authors":"Steve Lange , Matthew Isaacs , Martina Klinkenberg , David Read , Dirk Bosbach , Guido Deissmann","doi":"10.1016/j.apgeochem.2025.106301","DOIUrl":"10.1016/j.apgeochem.2025.106301","url":null,"abstract":"<div><div>Iodine-129 (<sup>129</sup>I) is an important radionuclide in the context of nuclear waste disposal owing to its long half-life and potentially high mobility in the environment. The uptake of iodide and iodate by cement hydration phases, including calcium silicate hydrates (CSH), AFm and ettringite, as well as hardened cement paste made from Ordinary Portland cement, has been studied in batch-type sorption experiments to enhance understanding of iodine retention mechanisms in engineered repositories. Uptake kinetics were generally fast, leading to steady state within 30 days. Strong uptake of iodine by AFm and ettringite was observed, the mechanism dependent on the iodine speciation. Iodide is retained in both AFm and ettringite by exchange for sulphate, whereas with iodate, iodate-substituted ettringite is formed by phase transformation or ion exchange in the case of AFm and ettringite, respectively. The contribution of CSH phases to iodine retention in cementitious systems depends on the Ca/Si-ratio of the CSH and the alkalinity of the solution, with stronger retention in young hyperalkaline cementitious materials. These findings have implications when selecting grouts for the immobilisation of radioactive waste streams containing <sup>129</sup>I or for choosing cementitious grouts and/or backfill materials in nuclear waste repositories.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"181 ","pages":"Article 106301"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419163","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.2024.106276
Fuyang Huang , Zikuang Xu , Fei Liu
Volatile organic compounds (VOCs) are widespread contaminants in groundwater and their concentrations have been extensively investigated. However, the variability of VOCs' concentrations in groundwater from scattered industry and drainage river is unclear. The occurrence and profiles of 55 VOCs in groundwater were evaluated using 148 field samples tested with purge-and-trap gas chromatography and linked mass spectrometry. The study showed that the overall detection frequencies and concentrations of VOCs in groundwater samples from scattered industry were higher than those observed in drainage river. Tetrachlorethylene and its dechlorination products, methyl chloride, and gasoline compounds and additives were the chemicals detected at high concentrations and high detection frequencies. Methyl tert-butyl ether and naphthalene were the most frequently detected (in 62.16% and 50.68% of the samples, respectively). The groundwater concentrations of 6 VOCs only found in scattered industry exceeded China's Class III limits (GB 14848-2017) in between 2.5% and 19% of the samples. Statistical analysis revealed a significant correlation between the cumulative concentration of VOCs and the total number of detections or detection frequency (p < 0.05). Due to the migration and transformation of VOCs in groundwater, the positive correlation pairs between individual VOCs show a significant decreasing trend between scattered industry and drainage river. Furthermore, a significant negative relationship was established between the adsorption affinity of VOCs and the ratio of standard deviation for drainage river and scattered industry (p < 0.05). Field proof and numerical simulation results simultaneously demonstrated that standard deviation reduction of concentration decreases significantly between scattered industry and drainage river under adsorption effects. Notably, the magnitude of the reduction in concentration variability was found to be positively correlated with the adsorption performance of the substances studied. These findings provide valuable insight into the distribution, migration and transformation of a wide range of VOCs in groundwater.
{"title":"Adsorption decreases the variability of volatile organic compounds’ concentrations in groundwater","authors":"Fuyang Huang , Zikuang Xu , Fei Liu","doi":"10.1016/j.apgeochem.2024.106276","DOIUrl":"10.1016/j.apgeochem.2024.106276","url":null,"abstract":"<div><div>Volatile organic compounds (VOCs) are widespread contaminants in groundwater and their concentrations have been extensively investigated. However, the variability of VOCs' concentrations in groundwater from scattered industry and drainage river is unclear. The occurrence and profiles of 55 VOCs in groundwater were evaluated using 148 field samples tested with purge-and-trap gas chromatography and linked mass spectrometry. The study showed that the overall detection frequencies and concentrations of VOCs in groundwater samples from scattered industry were higher than those observed in drainage river. Tetrachlorethylene and its dechlorination products, methyl chloride, and gasoline compounds and additives were the chemicals detected at high concentrations and high detection frequencies. Methyl <em>tert</em>-butyl ether and naphthalene were the most frequently detected (in 62.16% and 50.68% of the samples, respectively). The groundwater concentrations of 6 VOCs only found in scattered industry exceeded China's Class III limits (GB 14848-2017) in between 2.5% and 19% of the samples. Statistical analysis revealed a significant correlation between the cumulative concentration of VOCs and the total number of detections or detection frequency (<em>p</em> < 0.05). Due to the migration and transformation of VOCs in groundwater, the positive correlation pairs between individual VOCs show a significant decreasing trend between scattered industry and drainage river. Furthermore, a significant negative relationship was established between the adsorption affinity of VOCs and the ratio of standard deviation for drainage river and scattered industry (<em>p</em> < 0.05). Field proof and numerical simulation results simultaneously demonstrated that standard deviation reduction of concentration decreases significantly between scattered industry and drainage river under adsorption effects. Notably, the magnitude of the reduction in concentration variability was found to be positively correlated with the adsorption performance of the substances studied. These findings provide valuable insight into the distribution, migration and transformation of a wide range of VOCs in groundwater.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106276"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177912","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}
The hydrogeological system in the upper basin of Oum-Er-Rabiaa, characterized by a semi-arid climate, is facing ongoing water quality degradation primarily due to rising salinity. This study applies geochemical and stable isotope tracers to investigate the impact of geogenic features and processes on the origin and geochemical characteristics of water bodies. Hydrochemical analysis reveals significant spatial variation in mineralization, with two distinct groups of springs: (i) freshwater springs with high flow rates (≈12–14 m³/s) and low salinity (≈0.7 g/L) and (ii) saline springs with lower flow rates (≈0.8–0.9 m³/s) and high salinity (≈19 g/L). This variation reflects a transition in water chemistry from Calcium–Magnesium-Bicarbonate type in less saline waters to Chloride-Sodium–Potassium type in more mineralized waters. The main geochemical processes contributing to salinity include water-rock interaction, ion exchange, and residence time. Isotopic tracing identifies potential recharge areas originating from the high elevations of the Middle Atlas Mountains, through outcrops of Liassic limestones and Triassic sedimentary formations. It also highlights an evaporation process occurring within the system, which increases salinity in many locations.
{"title":"Geochemical, isotopic and geogenic tracing of a mountainous hydrogeological system: Case of the springs area in the upper basin of Oum-Er-Rabiaa River (Middle Atlas, Morocco)","authors":"Amine Tahiri , Fouad Amraoui , Lhoussaine Bouchaou , Mohamed Sinan","doi":"10.1016/j.apgeochem.2025.106288","DOIUrl":"10.1016/j.apgeochem.2025.106288","url":null,"abstract":"<div><div>The hydrogeological system in the upper basin of Oum-Er-Rabiaa, characterized by a semi-arid climate, is facing ongoing water quality degradation primarily due to rising salinity. This study applies geochemical and stable isotope tracers to investigate the impact of geogenic features and processes on the origin and geochemical characteristics of water bodies. Hydrochemical analysis reveals significant spatial variation in mineralization, with two distinct groups of springs: (i) freshwater springs with high flow rates (≈12–14 m³/s) and low salinity (≈0.7 g/L) and (ii) saline springs with lower flow rates (≈0.8–0.9 m³/s) and high salinity (≈19 g/L). This variation reflects a transition in water chemistry from Calcium–Magnesium-Bicarbonate type in less saline waters to Chloride-Sodium–Potassium type in more mineralized waters. The main geochemical processes contributing to salinity include water-rock interaction, ion exchange, and residence time. Isotopic tracing identifies potential recharge areas originating from the high elevations of the Middle Atlas Mountains, through outcrops of Liassic limestones and Triassic sedimentary formations. It also highlights an evaporation process occurring within the system, which increases salinity in many locations.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106288"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177911","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.2025.106290
O. Almendros-Ginestà , S. Duckworth , P.Q. Fürst , T. Missana , M. Altmaier , X. Gaona
The impact of citrate (cit) on the solubility of Ni(II) was comprehensively investigated in alkaline 0.1–3.0 M NaCl–NaOH–Na3cit solutions in the absence and presence of 0.02 mol dm−3 CaCl2. Experiments were conducted at a temperature of (22 ± 2)°C under inert gas (Ar) atmosphere. Thermodynamic equilibrium was approached from undersaturation conditions using β-Ni(OH)2(cr).
The characterization by X-ray diffraction of selected solid phases after completing the solubility experiments (∼360 days, depending upon experimental series) confirmed that β–Ni(OH)2(cr) controls the solubility of Ni(II) in all investigated systems, both in the absence and presence of Ca. In Ca-free systems, the observed increase in the solubility of Ni(II) is attributed to the formation of binary and ternary Ni(II)–OH–cit aqueous complexes. The use of thermodynamic data currently selected within the Thermochemical Database project of the Nuclear Energy Agency (NEA-TDB) clearly underestimates the solubility of Ni(II) in the hyperalkaline pHm regime of relevance in cementitious systems. Taking as anchoring point the species currently selected in the NEA-TDB (Ni(cit)– and Ni(cit)24−) and based on slope analysis of solubility data (log10 [Ni] vs. pHm and log10 [Ni] vs. log10 [cit]), the predominance of the complexes Ni(H–1cit)2–, Ni(OH)(H–1cit)3–, Ni(cit)(H–1cit)5– and Ni(H–1cit)26− at pHm ≥ 10 is proposed, with H–1cit corresponding to a citrate ligand with deprotonated alcohol group. The increase in solubility observed in the presence of Ca can only be explained claiming the formation of a quaternary complex, i.e., Ca[Ni(OH)(H–1cit)]–. Based on this chemical model and the fit of solubility data, thermodynamic and SIT activity models were derived for the system Na+–Ca2+–Ni2+–Cl––OH––cit3––H2O(l). These models can be implemented in thermodynamic databases and geochemical calculations, allowing for the first time an accurate description of Ni(II) solubility and aqueous speciation in citrate-containing cementitious systems.
在无 0.02 mol dm-3 CaCl2 和有 0.02 mol dm-3 CaCl2 的情况下，全面研究了柠檬酸盐（cit）在 0.1-3.0 M NaCl-NaOH-Na3cit 碱性溶液中对 Ni(II) 溶解度的影响。实验在温度为 (22 ± 2)°C 的惰性气体（Ar）环境下进行。在完成溶解度实验（视实验系列而定，需 ∼ 360 天）后，通过 X 射线衍射对所选固相的表征证实，β-Ni(OH)2(cr) 控制了所有研究体系中 Ni(II)的溶解度，无论是在无 Ca 还是有 Ca 的情况下。在不含 Ca 的体系中，观察到 Ni(II) 溶解度的增加是由于形成了二元和三元 Ni(II)-OH-cit 水络合物。使用核能机构热化学数据库项目（NEA-TDB）中目前选定的热力学数据，显然低估了 Ni（II）在水泥基体系中相关的超碱性 pHm 体系中的溶解度。以 NEA-TDB 目前选定的物种（Ni(cit)- 和 Ni(cit)24-）为锚点，基于溶解度数据的斜率分析（log10 [Ni] vs. pHm 和 log10 [Ni] vs. log10 [cit]），可以得出以下结论log10[Ni]与 log10 [cit]的关系），认为在 pHm ≥ 10 时主要是 Ni(H-1cit)2-、Ni(OH)(H-1cit)3-、Ni(cit)(H-1cit)5- 和 Ni(H-1cit)26- 复合物，其中 H-1cit 与带有去质子化醇基的柠檬酸配体相对应。在 Ca 存在下观察到的溶解度增加只能解释为形成了四元复合物，即 Ca[Ni(OH)(H-1cit)]- 。根据这一化学模型和溶解度数据的拟合，得出了 Na+-Ca2+-Ni2+-Cl--OH--cit3--H2O(l)体系的热力学模型和 SIT 活性模型。这些模型可用于热力学数据库和地球化学计算，从而首次准确地描述了含柠檬酸盐的胶凝体系中 Ni(II) 的溶解度和水相标示。
{"title":"Thermodynamic description of the Ni(II)-citrate system in alkaline, dilute to concentrated NaCl solutions. Formation of quaternary complexes with ca","authors":"O. Almendros-Ginestà , S. Duckworth , P.Q. Fürst , T. Missana , M. Altmaier , X. Gaona","doi":"10.1016/j.apgeochem.2025.106290","DOIUrl":"10.1016/j.apgeochem.2025.106290","url":null,"abstract":"<div><div>The impact of citrate (cit) on the solubility of Ni(II) was comprehensively investigated in alkaline 0.1–3.0 M NaCl–NaOH–Na<sub>3</sub>cit solutions in the absence and presence of 0.02 mol dm<sup>−3</sup> CaCl<sub>2</sub>. Experiments were conducted at a temperature of (22 ± 2)°C under inert gas (Ar) atmosphere. Thermodynamic equilibrium was approached from undersaturation conditions using β-Ni(OH)<sub>2</sub>(cr).</div><div>The characterization by X-ray diffraction of selected solid phases after completing the solubility experiments (∼360 days, depending upon experimental series) confirmed that β–Ni(OH)<sub>2</sub>(cr) controls the solubility of Ni(II) in all investigated systems, both in the absence and presence of Ca. In Ca-free systems, the observed increase in the solubility of Ni(II) is attributed to the formation of binary and ternary Ni(II)–OH–cit aqueous complexes. The use of thermodynamic data currently selected within the Thermochemical Database project of the Nuclear Energy Agency (NEA-TDB) clearly underestimates the solubility of Ni(II) in the hyperalkaline pH<sub>m</sub> regime of relevance in cementitious systems. Taking as anchoring point the species currently selected in the NEA-TDB (Ni(cit)<sup>–</sup> and Ni(cit)<sub>2</sub><sup>4−</sup>) and based on slope analysis of solubility data (log<sub>10</sub> [Ni] <em>vs.</em> pH<sub>m</sub> and log<sub>10</sub> [Ni] <em>vs.</em> log<sub>10</sub> [cit]), the predominance of the complexes Ni(H<sub>–1</sub>cit)<sup>2–</sup>, Ni(OH)(H<sub>–1</sub>cit)<sup>3–</sup>, Ni(cit)(H<sub>–1</sub>cit)<sup>5–</sup> and Ni(H<sub>–1</sub>cit)<sub>2</sub><sup>6−</sup> at pH<sub>m</sub> ≥ 10 is proposed, with H<sub>–1</sub>cit corresponding to a citrate ligand with deprotonated alcohol group. The increase in solubility observed in the presence of Ca can only be explained claiming the formation of a quaternary complex, <em>i.e.</em>, Ca[Ni(OH)(H<sub>–1</sub>cit)]<sup>–</sup>. Based on this chemical model and the fit of solubility data, thermodynamic and SIT activity models were derived for the system Na<sup>+</sup>–Ca<sup>2+</sup>–Ni<sup>2+</sup>–Cl<sup>–</sup>–OH<sup>–</sup>–cit<sup>3–</sup>–H<sub>2</sub>O(l). These models can be implemented in thermodynamic databases and geochemical calculations, allowing for the first time an accurate description of Ni(II) solubility and aqueous speciation in citrate-containing cementitious systems.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106290"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178804","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.2025.106294
Huiting Liu , Tong Li , Jiaying Zhang , Pu Xu , Xiujian Xia , Yongjin Yu , Lin Liu , Huisu Chen
Experiments and field observations have shown that adding silica can to some extent mitigate strength retrogression of well cement exposed to high temperatures by generating tobermorite and xonotlite and inhibiting the formation of α-C2SH. However, the critical temperatures and silica dosage for formations of α-C2SH, tobermorite, and xonotlite in well cement are unknown due to the lack of appropriate thermodynamic database information. Therefore, an extended and internally consistent thermodynamic database is constructed for the CaO–SiO2–H2O system at high temperatures, and the critical temperature and silica dosage are investigated using a thermodynamic modeling technique based on the established database. The predicted phase assemblage of well cement at various temperatures and silica dosages is verified by XRD data from the literature and our experiments. The gel-space ratio, which is defined by Pichler as the ratio of the total volume of all hydration products over the volume of both all hydration products and capillary pores, is used to establish the relationship between phase composition and compressive strength. If combined with a well-built composition-structure-performance micromechanic model, the thermodynamic modeling technique can be used to guide the mix proportion design of well cement.
{"title":"Thermodynamic mechanism of silica dosage and temperature on phase composition of well cement at high temperature and its impact on macro-properties","authors":"Huiting Liu , Tong Li , Jiaying Zhang , Pu Xu , Xiujian Xia , Yongjin Yu , Lin Liu , Huisu Chen","doi":"10.1016/j.apgeochem.2025.106294","DOIUrl":"10.1016/j.apgeochem.2025.106294","url":null,"abstract":"<div><div>Experiments and field observations have shown that adding silica can to some extent mitigate strength retrogression of well cement exposed to high temperatures by generating tobermorite and xonotlite and inhibiting the formation of α-C<sub>2</sub>SH. However, the critical temperatures and silica dosage for formations of α-C<sub>2</sub>SH, tobermorite, and xonotlite in well cement are unknown due to the lack of appropriate thermodynamic database information. Therefore, an extended and internally consistent thermodynamic database is constructed for the CaO–SiO<sub>2</sub>–H<sub>2</sub>O system at high temperatures, and the critical temperature and silica dosage are investigated using a thermodynamic modeling technique based on the established database. The predicted phase assemblage of well cement at various temperatures and silica dosages is verified by XRD data from the literature and our experiments. The gel-space ratio, which is defined by Pichler as the ratio of the total volume of all hydration products over the volume of both all hydration products and capillary pores, is used to establish the relationship between phase composition and compressive strength. If combined with a well-built composition-structure-performance micromechanic model, the thermodynamic modeling technique can be used to guide the mix proportion design of well cement.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106294"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178828","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.2024.106275
Pankaj Srivastava , Manini Aruche , Dilip K. Pal , Rohit Kumar , Abdul Hameed , A. Arya , L.P. Singh
The Ganga Basin (GB), occupying a unique position in front of the rising Himalayas, is one of the largest fluvial sedimentary basins in the world. Over the last 13.5 ka, the overbank sediments of this basin were modified by pedogenesis. Previous studies of GB soils have established soil geomorphology, micromorphology, and clay mineralogy. However, the information on geochemical evolution and chemical weathering during the pedogenesis of these sediments is unknown. This study provides the geochemical characteristics of 31 pedons representing the entire GB along a 2000 km west-east transect to understand silicate weathering during pedogenesis. The absence of lithological discontinuity and the Ti/Al ratio values confirmed that chemical weathering in these pedons is due to pedogenesis. The depth functions (<50 cm to >50 cm) of the major oxides, weathering indices, and age relationship of the soils show that the Western Yamuna Plains (WYP: Pedons 1–10), Yamuna-Ganga Interfluve (YGI: Pedons 11–15), and Ganga–Ghaghara Interfluve (GGI: Pedons 16–25) are characterised by weak, intermediate, and strong chemical weathering during the pedogenesis of the alluvium derived from the Himalayas. In contrast, the deltaic plains (DP: Pedons 26–31) show weak to intermediate chemical weathering during the pedogenesis, with a major input of the cratonic flux. The major cations show enrichment as Ca > Mg > Mn > Fe > Na > Al > K > P, with a minor depletion of silica and no change in Ti during pedogenesis in GB soils. The rate of chemical weathering shows an increase of the weathering indices (CIA, CIA-K, CALMAG) by 1.5%–1.7% in the Bw, Bt, and Bss horizons over 1000 years of pedogenesis in the Ganga Basin.
{"title":"Soil-geochemistry of the Ganga basin along a 2000 km transect: Implications for chemical weathering during pedogenesis influenced by source, climate, and neotectonics","authors":"Pankaj Srivastava , Manini Aruche , Dilip K. Pal , Rohit Kumar , Abdul Hameed , A. Arya , L.P. Singh","doi":"10.1016/j.apgeochem.2024.106275","DOIUrl":"10.1016/j.apgeochem.2024.106275","url":null,"abstract":"<div><div>The Ganga Basin (GB), occupying a unique position in front of the rising Himalayas, is one of the largest fluvial sedimentary basins in the world. Over the last 13.5 ka, the overbank sediments of this basin were modified by pedogenesis. Previous studies of GB soils have established soil geomorphology, micromorphology, and clay mineralogy. However, the information on geochemical evolution and chemical weathering during the pedogenesis of these sediments is unknown. This study provides the geochemical characteristics of 31 pedons representing the entire GB along a 2000 km west-east transect to understand silicate weathering during pedogenesis. The absence of lithological discontinuity and the Ti/Al ratio values confirmed that chemical weathering in these pedons is due to pedogenesis. The depth functions (<50 cm to >50 cm) of the major oxides, weathering indices, and age relationship of the soils show that the Western Yamuna Plains (WYP: Pedons 1–10), Yamuna-Ganga Interfluve (YGI: Pedons 11–15), and Ganga–Ghaghara Interfluve (GGI: Pedons 16–25) are characterised by weak, intermediate, and strong chemical weathering during the pedogenesis of the alluvium derived from the Himalayas. In contrast, the deltaic plains (DP: Pedons 26–31) show weak to intermediate chemical weathering during the pedogenesis, with a major input of the cratonic flux. The major cations show enrichment as Ca > Mg > Mn > Fe > Na > Al > K > P, with a minor depletion of silica and no change in Ti during pedogenesis in GB soils. The rate of chemical weathering shows an increase of the weathering indices (CIA, CIA-K, CALMAG) by 1.5%–1.7% in the Bw, Bt, and Bss horizons over 1000 years of pedogenesis in the Ganga Basin.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106275"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177913","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.2024.106274
Allan M. M. Leal , Tim Tambach , Diego Volpatto , Xiaodong Liang , Philip Loldrup Fosbøl , Kaj Thomsen
The extended UNIQUAC model is a thermodynamic model able to estimate thermodynamic properties of aqueous electrolyte solutions under a wide range of temperature, pressure, and composition conditions. Thermodynamic properties include species activity coefficients, excess molar Gibbs energy, excess molar enthalpy, excess molar heat capacity. These properties are important for aqueous speciation calculations, mineral and gas solubility computations, chemical kinetic modeling of mineral dissolution and precipitation, and in reactive transport simulations considering chemically complex aqueous electrolyte solutions. In this paper we present a brief literature review on the extended UNIQUAC model, we report on its implementation in C++ in the Reaktoro framework for modeling chemically reactive systems, and we show its use from Python for computing mineral and gas solubilities in aqueous solutions at a wide range of temperature, pressure, and salinity conditions. We validated the calculations against experimental data and results obtained through the software ScaleCERE implementing the extended UNIQUAC model. Our conclusion is that the extended UNIQUAC model has been successfully implemented into the Reaktoro framework, thereby providing a suitable activity model for geochemical and reactive transport modeling.
{"title":"Using Reaktoro for mineral and gas solubility calculations with the Extended UNIQUAC model","authors":"Allan M. M. Leal , Tim Tambach , Diego Volpatto , Xiaodong Liang , Philip Loldrup Fosbøl , Kaj Thomsen","doi":"10.1016/j.apgeochem.2024.106274","DOIUrl":"10.1016/j.apgeochem.2024.106274","url":null,"abstract":"<div><div>The extended UNIQUAC model is a thermodynamic model able to estimate thermodynamic properties of aqueous electrolyte solutions under a wide range of temperature, pressure, and composition conditions. Thermodynamic properties include species activity coefficients, excess molar Gibbs energy, excess molar enthalpy, excess molar heat capacity. These properties are important for aqueous speciation calculations, mineral and gas solubility computations, chemical kinetic modeling of mineral dissolution and precipitation, and in reactive transport simulations considering chemically complex aqueous electrolyte solutions. In this paper we present a brief literature review on the extended UNIQUAC model, we report on its implementation in C++ in the Reaktoro framework for modeling chemically reactive systems, and we show its use from Python for computing mineral and gas solubilities in aqueous solutions at a wide range of temperature, pressure, and salinity conditions. We validated the calculations against experimental data and results obtained through the software ScaleCERE implementing the extended UNIQUAC model. Our conclusion is that the extended UNIQUAC model has been successfully implemented into the Reaktoro framework, thereby providing a suitable activity model for geochemical and reactive transport modeling.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106274"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178830","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.2025.106296
Melissa A.H. Turcotte , Heather E. Jamieson , Michael B. Parsons
Historical mine tailings in the Cobalt Mining Camp in northern Ontario are both a source of environmental contamination and a potential resource of critical metals. Widespread mining in the Cobalt area during the 20th century resulted in dozens of unremediated mine sites and at least 18 unconfined tailings deposits, which contain potentially hazardous metals and metalloids, including arsenic (As). Economic metals, including cobalt (Co), also occur in the waste and could be recovered. Geochemical and mineralogical analyses of tailings and pond sediments were performed to assess the mobility of Co and other metal(loid)s in different depositional environments and implications for reprocessing of the mine wastes.
Tailings from four sites and benthic sediments from a pond impacted by tailings were characterized using ICP-ES/MS, various mineralogical techniques, and shake flask experiments. Cobalt concentrations in the tailings and sediments (96.8–8900 mg kg−1 Co; median = 470 mg kg−1) exceed Canadian environmental quality guidelines for residential soils (50 mg kg−1 Co) at all sample sites. Mineralogical investigations reveal that Co is hosted in oxidized alteration phases in near-surface tailings along with primary sulfide and arsenide minerals, which persist in this environment. In submerged tailings, Co is contained mainly within primary sulfide and arsenide minerals and reduced secondary phases. Cobalt-bearing chlorite is a major host of Co in half of the tailings samples, containing up to 50 wt% of the total Co content; the presence of Co-bearing chlorite may impact potential recovery of Co from the tailings in the future. The mineralogy of the benthic pond sediments is heterogeneous; however, Co is sequestered in both primary sulfide and arsenide minerals and authigenic reduced phases such as Co-bearing sulfide.
The results of shake flask experiments reveal that Co in the tailings and sediments dissolves in deionized water under oxidizing conditions. The concentration of Co in the leachate (30–126,000 μg L−1 Co) consistently exceeds Canadian water quality guidelines for Co (1 μg L−1). The results of this study provide new insight about the controls on metal(loid) mobility, including the processes which impact metal(loid) cycling in reduced pond sediments and the occurrence of Co-bearing chlorite in the tailings. In addition to characterizing the risks associated with mine waste contamination and informing long-term waste management decisions, the results of this study may be applied to understand the potential for future Co recovery from mine waste and sediments in the Cobalt area.
{"title":"Mobility of cobalt in mine waste: Evidence from a historic silver mining district in Canada","authors":"Melissa A.H. Turcotte , Heather E. Jamieson , Michael B. Parsons","doi":"10.1016/j.apgeochem.2025.106296","DOIUrl":"10.1016/j.apgeochem.2025.106296","url":null,"abstract":"<div><div>Historical mine tailings in the Cobalt Mining Camp in northern Ontario are both a source of environmental contamination and a potential resource of critical metals. Widespread mining in the Cobalt area during the 20th century resulted in dozens of unremediated mine sites and at least 18 unconfined tailings deposits, which contain potentially hazardous metals and metalloids, including arsenic (As). Economic metals, including cobalt (Co), also occur in the waste and could be recovered. Geochemical and mineralogical analyses of tailings and pond sediments were performed to assess the mobility of Co and other metal(loid)s in different depositional environments and implications for reprocessing of the mine wastes.</div><div>Tailings from four sites and benthic sediments from a pond impacted by tailings were characterized using ICP-ES/MS, various mineralogical techniques, and shake flask experiments. Cobalt concentrations in the tailings and sediments (96.8–8900 mg kg<sup>−1</sup> Co; median = 470 mg kg<sup>−1</sup>) exceed Canadian environmental quality guidelines for residential soils (50 mg kg<sup>−1</sup> Co) at all sample sites. Mineralogical investigations reveal that Co is hosted in oxidized alteration phases in near-surface tailings along with primary sulfide and arsenide minerals, which persist in this environment. In submerged tailings, Co is contained mainly within primary sulfide and arsenide minerals and reduced secondary phases. Cobalt-bearing chlorite is a major host of Co in half of the tailings samples, containing up to 50 wt% of the total Co content; the presence of Co-bearing chlorite may impact potential recovery of Co from the tailings in the future. The mineralogy of the benthic pond sediments is heterogeneous; however, Co is sequestered in both primary sulfide and arsenide minerals and authigenic reduced phases such as Co-bearing sulfide.</div><div>The results of shake flask experiments reveal that Co in the tailings and sediments dissolves in deionized water under oxidizing conditions. The concentration of Co in the leachate (30–126,000 μg L<sup>−1</sup> Co) consistently exceeds Canadian water quality guidelines for Co (1 μg L<sup>−1</sup>). The results of this study provide new insight about the controls on metal(loid) mobility, including the processes which impact metal(loid) cycling in reduced pond sediments and the occurrence of Co-bearing chlorite in the tailings. In addition to characterizing the risks associated with mine waste contamination and informing long-term waste management decisions, the results of this study may be applied to understand the potential for future Co recovery from mine waste and sediments in the Cobalt area.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"181 ","pages":"Article 106296"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387223","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.2025.106298
George J.L. Wilson , David A. Aind , Abhijit Mukherjee , David A. Polya , Daren C. Gooddy , Laura A. Richards
Groundwater contamination is a considerable threat to public health in many regions of the world. Strong seasonal variation in monsoon-affected regions can have significant effects on groundwater quality, yet these variations are not fully understood. Using excitation-emission matrix (EEM) fluorescent spectroscopy, we explore the seasonal dynamics of dissolved organic matter (DOM) composition along a transect in West Bengal, India. Groundwater, river water and ponds were sampled (n = 59) on a weekly/fortnightly basis, from the onset of monsoon to late-July, to gain an understanding of DOM temporal dynamics in aquifers at a critical point in seasonal hydrological conditions. Several fluorescent DOM (fDOM) components and indices were used to infer the source and nature of DOM. Although dissolved organic carbon (DOC) remained consistent throughout the sample timeframe, precipitation-associated spikes in fluorescence index (FI), specific ultraviolet absorbance (SUVA254) and redox potential (Eh) likely point towards rainfall-induced increase of autochthonous DOM and the increase of microbial metabolic activity in response to oxygenated recharge. We suggest that observed fluctuations in organics were associated with concomitant changes in redox- and solubility-controlled elements (e.g. Fe and Mg), thus having wider implications on groundwater geochemistry and particularly the mobility of redox- and organic-sensitive solutes.
{"title":"Monsoonal rainfall initiates autochthonous alteration of dissolved organic matter composition in Indian groundwaters","authors":"George J.L. Wilson , David A. Aind , Abhijit Mukherjee , David A. Polya , Daren C. Gooddy , Laura A. Richards","doi":"10.1016/j.apgeochem.2025.106298","DOIUrl":"10.1016/j.apgeochem.2025.106298","url":null,"abstract":"<div><div>Groundwater contamination is a considerable threat to public health in many regions of the world. Strong seasonal variation in monsoon-affected regions can have significant effects on groundwater quality, yet these variations are not fully understood. Using excitation-emission matrix (EEM) fluorescent spectroscopy, we explore the seasonal dynamics of dissolved organic matter (DOM) composition along a transect in West Bengal, India. Groundwater, river water and ponds were sampled (<em>n</em> = 59) on a weekly/fortnightly basis, from the onset of monsoon to late-July, to gain an understanding of DOM temporal dynamics in aquifers at a critical point in seasonal hydrological conditions. Several fluorescent DOM (fDOM) components and indices were used to infer the source and nature of DOM. Although dissolved organic carbon (DOC) remained consistent throughout the sample timeframe, precipitation-associated spikes in fluorescence index (FI), specific ultraviolet absorbance (SUVA<sub>254</sub>) and redox potential (<em>Eh</em>) likely point towards rainfall-induced increase of autochthonous DOM and the increase of microbial metabolic activity in response to oxygenated recharge. We suggest that observed fluctuations in organics were associated with concomitant changes in redox- and solubility-controlled elements (<em>e.g.</em> Fe and Mg), thus having wider implications on groundwater geochemistry and particularly the mobility of redox- and organic-sensitive solutes.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"181 ","pages":"Article 106298"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143167091","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}
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