Geochemical Transactions最新文献

{"title":"Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings","authors":"Philip A. Adene,&nbsp;Mojtaba Abdolahnezhad,&nbsp;Mian N. Anwar,&nbsp;Ania C. Ulrich,&nbsp;Matthew B. J. Lindsay","doi":"10.1186/s12932-025-00104-3","DOIUrl":"10.1186/s12932-025-00104-3","url":null,"abstract":"<div><p>Bitumen extraction from mined oil sands ore generates a large volume of fluid fines tailings (FFT) that must be incorporated into either aquatic or terrestrial reclamation landforms. Mine operators are developing various tailings technologies to accelerate FFT dewatering, including the addition of chemical coagulants and flocculants. However, the impacts of these coagulants and flocculants on biogeochemical processes in treated FFT are not fully understood. We conducted anaerobic batch experiments to examine the influence of different doses (i.e., 0, 500, 1000, and 1500 ppm) of sulfate-based coagulants, including aluminum sulfate (alum) [Al₂(SO₄)₃∙<i>n</i>H₂O], ferric sulfate (ferric) [Fe₂(SO₄)₃∙<i>n</i>H₂O], and calcium sulfate (gypsum) [CaSO₄∙2H₂O], on biogenic gas production and microbial communities in treated FFT. Our results show that sulfate addition stimulated microbial sulfate reduction, which inhibited methanogenesis in coagulated FFT relative to experimental controls. Sulfate depletion preceded increased methane production in the 500 ppm gypsum experiment, while larger ferric and alum doses produced higher sulfate concentrations and larger pH decreases. 16 S rRNA sequencing revealed that <i>Comamonadaceae</i>,<i> Anaerolineaceae</i>, and <i>Desulfocapsaceae</i> were the major bacterial families, while <i>Methanoregulaceae</i> and <i>Methanosaetaceae</i> dominated the archaeal families in all treatments. Precipitation of iron(II) sulfides limited dissolved hydrogen sulfide concentrations in experiments where Fe availability was not limited. Our results indicate that addition of sulfate-based coagulants can stimulate microbial sulfate reduction and suppress methanogenesis. However, resumption of methane production following sulfate depletion reveals complex interactions among biogeochemical reaction pathways. Overall, this study demonstrates that biogeochemical cycling of carbon, sulfur, and iron are important considerations for the development and implementation of tailings treatment technologies.</p></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"26 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-025-00104-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144868879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Geochemical processes and groundwater quality assessment in the Yamuna-Hindon interfluve region of Bagpat district, Western Uttar Pradesh, India","authors":"Gautam Chandra Mondal,&nbsp;Abhishek Pandey Bharat,&nbsp;Abhay Kumar Singh","doi":"10.1186/s12932-025-00102-5","DOIUrl":"10.1186/s12932-025-00102-5","url":null,"abstract":"<div><p>The present research work aims to understand the geochemistry of groundwater resources of the Yamuna—Hindon interfluve region of Bagpat district, Western Uttar Pradesh, India. The region is a part of Indo-Gangetic belt, one of the world's most fertile and intensely farmed areas. To investigate the geochemical processes governing groundwater quality, a total of 105 groundwater samples were collected during pre-monsoon season and analyzed for various physico-chemical parameters, namely, pH, electrical conductivity (EC), total dissolved solid (TDS), total hardness (TH), turbidity, major anions (HCO₃⁻, SO₄²⁻, F⁻, Cl⁻, NO₃⁻)_, cations (Ca²⁺, Mg²⁺, Na⁺, K⁺) following the methods outlined in the American Public Health Association (APHA). The dissolved heavy metals (Fe, Mn, Zn, Pb, Cu, Cr, Ni, As, Se, Co, Cd and Al) in groundwater were analyzed by ICP-MS following the instrument manual. The analysis results revealed that the groundwater is pre-dominantly neutral to mildly alkaline in nature. The major cation chemistry majorly followed the occurrence pattern of Na⁺ &gt; Mg²⁺ &gt; Ca²⁺ &gt; K⁺, while for anions it was HCO₃⁻ &gt; Cl⁻ &gt; SO₄²⁻ &gt; NO₃⁻ &gt; F⁻. The data plotted on Piper triangular diagram indicated that Ca²⁺-Mg²⁺-HCO₃⁻ and Na⁺-K⁺-HCO₃⁻-Cl⁻ were major hydrogeochemical facies. Weathering of rock-forming minerals mainly governed the groundwater geochemistry in this region, although part of the cations associated with Cl⁻, F⁻ and NO₃⁻ may originate from anthropogenic sources. TDS, TH, turbidity and F⁻ were identified as the major parameters that violated the prescribed limits for drinking water. Most of the heavy metals were found within the drinking water prescribed limits except for Fe, Mn, Al and Se. Elevated salinity, %Na, and magnesium hazard (MH) at certain sites limit its suitability for agricultural use. The assessment of selected organochlorine and organophosphorus pesticides in five samples indicated presence of lindane, β-endosulfan and DDT isomers in few samples. However, a detailed investigation of possible pesticide contamination in this intensive agriculture area is required before drawing any final conclusions.</p></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"26 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-025-00102-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144756012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Development of a kinetic-thermodynamic model for lime-stabilization of Na-bentonite","authors":"Tasneem Ahmadullah,&nbsp;Maria Chrysochoou","doi":"10.1186/s12932-025-00103-4","DOIUrl":"10.1186/s12932-025-00103-4","url":null,"abstract":"<div><p>This study presents the first kinetic model to predict the solid and pore solution composition of Na-bentonite clay reacting with slaked lime over a period of 720 days. The model successfully accounts for most experimental data using a single kinetic rate constant. The following sequence of reactions was predicted by the model: initial rapid dissolution of portlandite within the first 7 days, leading to a decrease in pH and dissolved calcium, and concurrent formation of calcium silicate hydrates (C-S-H: jennite), calcium aluminate hydrate (C-A-H: C₄AH₁₃), calcium aluminosilicate hydrates (stratlingite) and hydrotalcite. After 7 days, jennite and stratlingite are predicted to transform into tobermorite-II, contributing to strength development up to 28 days. From 28 to 90 days, continued montmorillonite dissolution is predicted, along with minor formation of ettringite, partial tobermorite-II dissolution, and precipitation of secondary phases such as albite and talc. Experimentally, portlandite dissolution was confirmed by TGA and XRD and found to be complete within 7 days, in agreement with model predictions. However, other predicted solid-phase transformations (e.g., tobermorite-II formation and dissolution, ettringite, albite, and talc formation) could not be conclusively verified through experimental techniques. Aqueous phase measurements confirmed that the pH and Ca trends in solution, and that equilibrium was reached by 90 days.</p></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"26 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-025-00103-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144747398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Major ion chemistry and suitability of groundwater resources for different utilizations in mica mining areas, Jharkhand, India","authors":"Soma Giri,&nbsp;Ashwani Kumar Tiwari,&nbsp;Mukesh Kumar Mahato,&nbsp;Abhay Kumar Singh","doi":"10.1186/s12932-025-00099-x","DOIUrl":"10.1186/s12932-025-00099-x","url":null,"abstract":"<div><p>Groundwater resources in mica mining areas of Jharkhand are vital for local communities, agriculture, and domestic utilization. The study investigates the major ion chemistry of groundwater in the mica mining regions, focusing on key physicochemical parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS), and concentrations of major cations (Ca²⁺, Mg²⁺, Na⁺, K⁺) and anions (HCO₃⁻, Cl⁻, SO₄²⁻, NO₃⁻, F⁻). Groundwater samples from the study area were collected before the monsoon season, during the monsoon season, and after the monsoon season. The hydro-chemical analysis reveals that groundwater in the mica mining zones exhibits elevated levels of dissolved ions, with NO₃⁻, F⁻, Ca²⁺, Mg²⁺ and total hardness exceeding permissible limits set by Bureau of Indian Standards (BIS) for drinking purposes at some locations. Water Quality Index (WQI) assessments suggest that a significant proportion of groundwater samples fall into the “good” to “very good” category for drinking and about 29% of the samples fall under the “poor” category. The groundwater was generally suitable for irrigational use with exception of a few due to high salinity. The principal component analysis revealed rock weathering as a dominant source of ions along with anthropogenic sources like mining and agriculture contributing minorly to the ionic load. The predominant hydro-chemical facies identified were Ca-Mg-HCO₃ and Ca-Mg-Cl-SO₄ types. Both carbonate and silicate weathering play an important role in the geochemical signature of the groundwater in the area. The study implicates the potential health impacts of using the groundwater as drinking water without treatment at a few locations owing to high fluoride, nitrate and dissolved solids. The study also highlights the need for sustainable water management practices and regular monitoring of groundwater quality to mitigate the anthropogenic impacts on groundwater resources.</p></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"26 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-025-00099-x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144090994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Correction: Probing atomic‑scale processes at the ferrihydrite‑water interface with reactive molecular dynamics","authors":"Ardalan Hayatifar,&nbsp;Simon Gravelle,&nbsp;Beatriz D. Moreno,&nbsp;Valerie A. Schoepfer,&nbsp;Matthew B. J. Lindsay","doi":"10.1186/s12932-025-00101-6","DOIUrl":"10.1186/s12932-025-00101-6","url":null,"abstract":"","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"26 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-025-00101-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143939911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Health and ecological risk assessment of metals in surface water from the Himalayan tributaries of the Ganga river, India","authors":"Md Maroof Azam,&nbsp;Jayant K. Tripathi","doi":"10.1186/s12932-025-00100-7","DOIUrl":"10.1186/s12932-025-00100-7","url":null,"abstract":"<div><p>This study investigates the trace element concentrations in the surface waters of four north-joining Himalayan tributaries of the Ganga river (Ramganga, Ghaghara, Gandak, and Kosi), highlighting the combined effects of geogenic processes and anthropogenic activities on trace element chemistry and water quality. A knowledge gap exists in understanding the sources of trace elements in these tributaries and the contribution of trace elements from these tributaries to the Gangariver. The novelty of the study lies in its assessment of sources, human health risks, and ecological impacts. The investigation was conducted by assessing trace element concentrations and comparing them with national and international standards. Various human health and ecological risk indicators, including the Heavy Metal Pollution Index (HPI), Hazard Quotient (HQ), Health Index (HI), Chronic Daily Intake (CDI), and the Potential Ecological Risk Index (PERI), were applied. The results reveal high concentrations of copper (Cu), zinc (Zn) and lead (Pb) in the Ramganga, indicating contamination from industrial activities in the catchment. Although most trace element concentrations are within safe limits, Pb concentration in the Ramganga exceeds the limit prescribed by WHO. The Ramganga shows the highest health risks, with a HI_total of 1.876 for adults and 1.616 for children. In contrast, the Ghaghara, Gandak, and Kosi exhibit lower but moderate contamination levels. HPI values for these rivers- 93.74 for the Ghaghara, 83.95 for the Kosi, 83.13 for the Gandak, and 80.43 for the Ramganga—indicate that although contamination is below critical thresholds, targeted mitigation strategies are needed. The findings provide valuable insights into trace metal sources and their implications for human health and ecological risks, and emphasize the need for frequent monitoring and pollution control measures for maintaining sustainable water quality in these tributaries.</p></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"26 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-025-00100-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Indexical methods assessing PTEs distribution in Mahan river command area, central India’s coal mining zone","authors":"Nirmal Kumar,&nbsp;Mahendra Kumar Tiwari,&nbsp;Rambabu Singh,&nbsp;Sudhakar Singha,&nbsp;Soumya S. Singha,&nbsp;Prasad Babu.K","doi":"10.1186/s12932-025-00098-y","DOIUrl":"10.1186/s12932-025-00098-y","url":null,"abstract":"<div><p>The quality of water can significantly affect the regional water resources due to scarcity of potable water in industrial area. The purpose of this study was to explore potentially toxic trace elements (PTEs) contamination and their seasonal variations in different water sources within the coal mining area of the Mahan River command area, Central India. To achieve this, 96 water samples were collected across two distinct seasons and analysed for PTEs. The results indicate that during the pre-monsoon season, the concentrations of Mn (18%), Cu (4%), Pb (8%), Ni (18%), Cd (2%), Al (4%), Cr (2%), and Fe (30%) exceeded permissible limits. In the post-monsoon season, Mn (15%), Pb (6%), Ni (15%), Cd (2%), Al (15%), Fe (46%) and Ba (4%) surpassed the standards. The multiple groundwater pollution indexical methods further revealed that 14% [Heavy metal pollution index (HPI)], 14% [Heavy metal evaluation index (HEI)], 18% [Contamination index (CI)], 14% [the entropy-weight based HM contamination index (EHCI)] and 20% [Heavy metal index (HMI)] of the samples exceeded permissible thresholds during the pre-monsoon season. Similarly, during the post-monsoon period, 10% (HPI), 10% (HEI), 15% (CI), 15% (EHCI) and 17% (HMI) of the samples were above acceptable limits. The relationship between the pH of water and the total load of dissolved metals is established using Caboi plot, confirming that mine water from mine water from Bhatgaon Underground (UG), Mahamaya UG, and Mahan Opencast (OC) [PR40, PR41, PR42, PR43, PR47, and PR48], surrounding rivers, and groundwater sources, exhibited an “Acid-High Metal” characteristic. This suggests significant contamination from acid mine drainage and mineral dissolution. Apart from the anthropogenic inputs, geogenic and environmental processes are responsible for the current distribution of PTEs and their seasonal variations.</p></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"26 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-025-00098-y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Transformation and fate of Fe(III) in petroleum-hydrocarbon-contaminated soil and groundwater","authors":"Essouassi Elikem,&nbsp;David Bulmer,&nbsp;Kris Bradshaw,&nbsp;Ardalan Hayatifar,&nbsp;Matthew B. J. Lindsay,&nbsp;Steven D. Siciliano,&nbsp;Derek Peak","doi":"10.1186/s12932-025-00097-z","DOIUrl":"10.1186/s12932-025-00097-z","url":null,"abstract":"<div><p>In anoxic subsurface environments, low Fe(III) bioaccessibility greatly limits <i>in situ</i> biodegradation of petroleum hydrocarbons (PHCs). Ferric ammonium citrate is a soluble compound that has the potential to increase the bioaccessibility of Fe(III). However, in neutral to alkaline environments, Fe(III) hydrolysis can produce Fe(III) (oxyhydr)oxides that may subsequently transform or recrystallize to relatively stable and less bioaccessible phases. Accordingly, the objective of this study was to elucidate the transformation and fate of Fe(III) contributed by ferric ammonium citrate in a gasoline-contaminated subsurface environment that was undergoing <i>in situ</i> bioremediation. Ferric ammonium citrate, together with sodium tripolyphosphate, magnesium sulphate, and nitric acid, was continuously injected into the contaminated groundwater for about 22 weeks. Colloids in the groundwater (solid particles retained on a 0.45 <span>(upmu)</span>m filter) and soil cores were collected from the site. Fe speciation in these samples was characterized using X-ray absorption near edge structure (XANES) and Fourier transform infrared (FTIR) spectroscopy. The groundwater colloids (GWCs) contained mostly octahedrally coordinated Fe(III), but the subsoils contained both octahedrally coordinated Fe(III) and Fe(II). The fraction of Fe(II) in the subsoils generally increased after about 22 weeks of continuous amendment injection. Ferric ammonium citrate did not persist in the PHC-contaminated subsurface: the Fe(III) it contained was transformed to solid phases. Fe(III)-organic-matter (Fe(III)-OM) complex/coprecipitate and sulfate green rust were the major phases present in the GWCs; akaganeite, chloride green rust, vivianite, ferrihydrite, Fe(III)-silicate, and magnetite were present as minor phases. The subsoils contained three major phases: Fe(III)-OM complex/coprecipitate, magnetite, and calcium ferric silicate. The presence of major Fe(II) phases in the subsoils strongly indicate that secondary Fe(III) phases (especially Fe(III)-OM complex/coprecipitate) served as terminal electron acceptors during the microbial degradation of PHCs in the contaminated subsurface.</p></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"26 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-025-00097-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Dissolution and solubility of the calcium-nickel carbonate solid solutions [(Ca1−xNix)CO3] at 25 °C","authors":"Chengyou Ma,&nbsp;Xiaoke Nong,&nbsp;Fan Xu,&nbsp;Zongqiang Zhu,&nbsp;Peijie Nong,&nbsp;Fei Luo,&nbsp;Shen Tang,&nbsp;Lihao Zhang,&nbsp;Zhiqiang Kang,&nbsp;Yinian Zhu","doi":"10.1186/s12932-024-00096-6","DOIUrl":"10.1186/s12932-024-00096-6","url":null,"abstract":"<div><p>A series of the calcium-nickel carbonate solid solutions [(Ca_1−xNi_x)CO₃] were synthesized and their dissolution in N₂-degassed water (NDW) and CO₂-saturated water (CSW) at 25 °C was experimentally investigated. During dissolution of the synthetic solids (Ni-bearing calcite, amorphous Ca-bearing NiCO₃ and their mixtures), the Ni-calcite and the Ca-NiCO₃ dissolved first followed by the formation of the Ni-bearing aragonite-structure phases. After 240–300 days of dissolution in NDW, the water solutions achieved the stable Ca and Ni concentrations of 0.592–0.665 and 0.073–0.290 mmol/L for the solids with lower Ni/(Ca + Ni) mol ratios (X_Ni), or 0.608–0.721 and 0.273–0.430 mmol/L for the solids with higher X_Ni, respectively. After 240–300 days of dissolution in CSW, the water solutions achieved the stable Ca and Ni concentrations of 1.094–3.738 and 0.831–4.300 mmol/L, respectively. For dissolution in NDW and CSW, the mean values of log IAP (Ion activity products) in the final stable state (≈ log <i>K</i>_sp, Solubility product constants) were determined to be − 8.65 ± 0.04 and − 8.16 ± 0.11 for calcite [CaCO₃], respectively; − 8.50 ± 0.02 and − 7.69 ± 0.03 for the synthetical nickel carbonates [NiCO₃], respectively. In respect to the bulk composition of the (Ca_1−xNi_x)CO₃ solid solutions, the final log IAP showed the highest value when X_Ni = 0.10–0.30. Mostly, the mean values of log IAP increased with the increasing X_Ni in respect to the Ni-calcite, the Ni-aragonite and the amorphous Ca-Ni carbonate. The plotting of the experimental data on the Lippmann diagram for the (Ca_1−xNi_x)CO₃ solid solution using the predicted Guggenheim parameters of <i>a</i>₀ = 2.14 and <i>a</i>₁ = − 0.128 from a miscibility gap of X_Ni = 0.238 to 0.690 indicated that the solids dissolved incongruently and the final Ca and Ni concentrations in the water solutions were simultaneously limited by the minimum stoichiometric saturation curves for the Ni-calcite, Ni-aragonite and the amorphous Ca-Ni carbonate. During dissolution in NDW, the Ni²⁺ preferred to dissolve into the water solution and Ca²⁺ preferred to remain in the solid, while during dissolution in CSW for the solids with higher X_Ni, the Ca²⁺ preferred to dissolve into the water solution and Ni²⁺ preferred to remain in the solid. These findings provide valuable insights into understanding the mechanisms governing Ni geochemical cycle in natural environments.</p></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"25 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-024-00096-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Silicate coprecipitation reduces green rust crystal size and limits dissolution-precipitation during air oxidation","authors":"Aaron R. Betts,&nbsp;Matthew H. H. Fischel,&nbsp;Anna Evers,&nbsp;Ryan Tappero,&nbsp;Donald L. Sparks","doi":"10.1186/s12932-024-00093-9","DOIUrl":"10.1186/s12932-024-00093-9","url":null,"abstract":"<div><p>Green rusts (GR) are mixed-valence iron (Fe) hydroxides which form in reducing redox environments like riparian and wetland soils and shallow groundwater. In these environments, silicon (Si) can influence Fe oxides’ chemical and physical properties but its role in GR formation and subsequent oxidative transformation have not been studied starting at initial nucleation. Green rust sulfate [GR(SO₄)] and green rust carbonate [GR(CO₃)] were both coprecipitated from salts by base titration in increasing % mol Si (0, 1, 10, and 50). The minerals were characterized before and after rapid (24 h) aqueous air-oxidation by x-ray diffraction (XRD), scanning electron microscopy (SEM), Fe extended x-ray absorption fine structure spectroscopy (EXAFS), and N₂-BET surface area. Results showed that only GR(SO4) or GR(CO3) was formed at every tested Si concentration. Increasing % mol Si caused decreased plate size and increased surface area in GR(CO3) but not GR(SO4). GR plate basal thickness was not changed at any condition indicating a lack of Si interlayering. Air oxidation of GR(SO4) at all % mol Si contents transformed by dissolution and reprecipitation into lepidocrocite and goethite, favoring ferrihydrite with higher % Si content. Air oxidation of GR(CO3) transformed into magnetite and goethite but increasing Si caused GR to oxidize while retaining its hexagonal plate structure via solid-state oxidation. Our results indicate that Si has the potential to cause GR to form in smaller particles and upon air oxidation, Si can either stabilize the plate structure or alter transformation to ferrihydrite.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"25 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geochemicaltransactions.biomedcentral.com/counter/pdf/10.1186/s12932-024-00093-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142521726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}