Applied Geochemistry最新文献

{"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 ,&nbsp;Manini Aruche ,&nbsp;Dilip K. Pal ,&nbsp;Rohit Kumar ,&nbsp;Abdul Hameed ,&nbsp;A. Arya ,&nbsp;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 (&lt;50 cm to &gt;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 &gt; Mg &gt; Mn &gt; Fe &gt; Na &gt; Al &gt; K &gt; 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}

{"title":"Using Reaktoro for mineral and gas solubility calculations with the Extended UNIQUAC model","authors":"Allan M. M. Leal ,&nbsp;Tim Tambach ,&nbsp;Diego Volpatto ,&nbsp;Xiaodong Liang ,&nbsp;Philip Loldrup Fosbøl ,&nbsp;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}

{"title":"Mobility of cobalt in mine waste: Evidence from a historic silver mining district in Canada","authors":"Melissa A.H. Turcotte ,&nbsp;Heather E. Jamieson ,&nbsp;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⁻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.</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⁻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.</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}

{"title":"Monsoonal rainfall initiates autochthonous alteration of dissolved organic matter composition in Indian groundwaters","authors":"George J.L. Wilson ,&nbsp;David A. Aind ,&nbsp;Abhijit Mukherjee ,&nbsp;David A. Polya ,&nbsp;Daren C. Gooddy ,&nbsp;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 (SUVA₂₅₄) 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}

{"title":"Recent developments in ThermoChimie – A thermodynamic database used in radioactive waste management","authors":"B. Madé ,&nbsp;W. Bower ,&nbsp;S. Brassinnes ,&nbsp;E. Colàs ,&nbsp;L. Duro ,&nbsp;P. Blanc ,&nbsp;A. Lassin ,&nbsp;L. Harvey ,&nbsp;J.D. Begg","doi":"10.1016/j.apgeochem.2024.106273","DOIUrl":"10.1016/j.apgeochem.2024.106273","url":null,"abstract":"<div><div>ThermoChimie is a thermodynamic database project intended for use across the radioactive waste management community to support repository performance assessment, research and development activities, and potentially inform decisions about waste conditioning, reprocessing, and disposability. Established in 1995 by Andra (France), and now managed by a consortium that also includes NWS (UK) and ONDRAF/NIRAS (Belgium), it is currently moving towards the end of Phase 3 (December 2025) of the project with the recent release of ThermoChimie version 12a and a further version update anticipated in the next 18 months. This paper provides an overview of the ThermoChimie database with emphasis on the activities undertaken during Phase 3, including major updates of the Pd, Fe, Se, Ni, U, Np, Pu, Am, Cm, and Tc systems, inclusion of data for Cu, Be, and Hg, the further development of the XCheck© tool that facilitates database management, increased database compatibility with a range of geochemical codes (PHREEQC, TOUGHREACT, CrunchFlow, CHESS, GWB, Spana, PFLOTRAN), and expert consultation on the subjects of cement and zeolite phases and redox reactions to inform future development of the database. This considerable body of work ensures that the ThermoChimie database continues to provide accurate, consistent and complete (as far as practicable) thermodynamic data to the radioactive waste community and beyond.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"180 ","pages":"Article 106273"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How earthworms thrive and drive silicate rock weathering in an artificial organo-mineral system","authors":"Tullia Calogiuri ,&nbsp;Iris Janssens ,&nbsp;Alix Vidal ,&nbsp;Jan Willem Van Groenigen ,&nbsp;Tim Verdonck ,&nbsp;Thomas Corbett ,&nbsp;Jens Hartmann ,&nbsp;Anna Neubeck ,&nbsp;Harun Niron ,&nbsp;Reinaldy P. Poetra ,&nbsp;Lukas Rieder ,&nbsp;Thomas Servotte ,&nbsp;Abhijeet Singh ,&nbsp;Michiel Van Tendeloo ,&nbsp;Siegfried E. Vlaeminck ,&nbsp;Sara Vicca ,&nbsp;Mathilde Hagens","doi":"10.1016/j.apgeochem.2024.106271","DOIUrl":"10.1016/j.apgeochem.2024.106271","url":null,"abstract":"&lt;div&gt;&lt;div&gt;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 (&lt;em&gt;Aporrectodea caliginosa&lt;/em&gt; [Savigny] and &lt;em&gt;Allolobophora chlorotica&lt;/em&gt; [Savigny]) at four densities (10, 20, 25 and 30 earthworms kg&lt;sup&gt;−1&lt;/sup&gt; 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&lt;sup&gt;−1&lt;/sup&gt; organo-mineral mixture) and/or enzyme additions (laccase, urease and carbonic anhydrase at 20, 177 and 1955 units kg&lt;sup&gt;−1&lt;/sup&gt; organo-mineral mixture, respectively), three water irrigation rates (125, 250 and 375 mL day&lt;sup&gt;−1&lt;/sup&gt; kg&lt;sup&gt;−1&lt;/sup&gt; organo-mineral mixture) and three watering frequencies (one, two and five times day&lt;sup&gt;−1&lt;/sup&gt;). 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}

{"title":"Diffusion and retention of Co2+ and Zn2+ in compacted homocationic forms of illite: Role of the electrical double layer","authors":"Dimitra Zerva ,&nbsp;Martin A. Glaus ,&nbsp;John L. Provis ,&nbsp;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 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 (<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 ⁵⁷Co²⁺ and ⁶⁵Zn²⁺ in various background electrolyte concentrations and homoionic forms of illite was compared in terms of the effective diffusion coefficient <em>D</em>_<em>e</em> and the sorption distribution coefficient <em>R</em>_<em>d</em>. 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 ⁶⁵Zn²⁺ has higher <em>R</em>_<em>d</em> 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, <em>φ</em> follows the order <span><math><mrow><mi>L</mi><mi>i</mi><mo>≈</mo><mi>N</mi><mi>a</mi><mo>&gt;</mo><mi>K</mi><mo>&gt;</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}

{"title":"Contrasting sources and fate of ammonium in groundwater systems of two large alluvial-lacustrine basins","authors":"Qinghua Li ,&nbsp;Yaojin Xiong ,&nbsp;Yamin Deng ,&nbsp;Yiqun Gan ,&nbsp;Yao Du","doi":"10.1016/j.apgeochem.2025.106297","DOIUrl":"10.1016/j.apgeochem.2025.106297","url":null,"abstract":"<div><div>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.</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}

{"title":"A methodological study on the analysis of organic matter associated with iron oxides in marine sediments","authors":"Milad Ezzati ,&nbsp;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}

{"title":"Accumulation and maturation of organic matter in shales: The coal-bearing Permian Longtan Formation at Tucheng Syncline, Southwestern Guizhou, China","authors":"Qian Zhang ,&nbsp;Zhijun Jin ,&nbsp;Ende Deng ,&nbsp;Zaigang Xu ,&nbsp;Rukai Zhu ,&nbsp;Quanyou Liu ,&nbsp;Zhihua Yan ,&nbsp;Ke Hu ,&nbsp;Tianyu Zheng ,&nbsp;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_r) and Rock-Eval T_max 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_r and T_max values range from 1.19 to 1.84 %VR_r (the mean value is 1.48%VR_r) 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}