Applied Geochemistry最新文献

{"title":"Selective recovery of native copper from basalt tailings using alkaline glycinate solution","authors":"Wei Xiong ,&nbsp;Jonathan Yang ,&nbsp;Sophia Bauer","doi":"10.1016/j.apgeochem.2025.106416","DOIUrl":"10.1016/j.apgeochem.2025.106416","url":null,"abstract":"<div><div>Mafic and ultramafic rocks present an intriguing pathway for CO₂ capture through strategic enhancements to the natural silicate weathering cycle. Simultaneously, these rock types are often hosts to appreciable amounts of metals critical to U.S. energy independence, particularly in the context of alkaline mine tailings from historical metal mining. The research and scientific prerogative, then, is to identify promising mafic and ultramafic feedstocks and conduct exploratory studies to effectively recover these critical minerals while preserving the potential for mineral carbonation. The Keweenaw Peninsula of Michigan hosts the largest native Cu reservoir within basalt in the world and experienced a rich history of Cu production spanning from pre-historic times to the mid-1900s. Today, much of the Cu mining legacy remains as mine waste tailings. In this study, we examined the Cu extractability from Keweenaw Basalt tailings using a sodium glycinate solution, in comparison with acid and sodium hydroxide leaching. Experimental results showed an 85 % Cu extraction rate using sodium glycinate as the extraction solution with negligible release of other cations from the basalt. The kinetic and extraction mechanisms of Cu selective recovery using glycinate solution were discussed using time-resolved experimental data and kinetic geochemical modeling. Theoretical estimation of carbon mineralization potential of all the existing basalt waste tailings (∼500 million tons) can reach 85.5 MMT CO₂. A total of 0.786 MMT Cu can be recovered with sodium glycinate, with a value of 7.7 billion USD. This novel application of alkaline glycinate for selective Cu recovery from basalt mine tailings demonstrates the viability of selective metal recovery using a non-hazardous chemical while preserving CO₂ capture potential and presents a potential pathway toward reducing energy-related emissions and providing an unconventional domestic source of critical minerals.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"187 ","pages":"Article 106416"},"PeriodicalIF":3.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144072227","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":"Accurate prediction of carbon monoxide in aqueous solutions for geological sequestration applications","authors":"Li Sun ,&nbsp;Jierong Liang","doi":"10.1016/j.apgeochem.2025.106414","DOIUrl":"10.1016/j.apgeochem.2025.106414","url":null,"abstract":"<div><div>Accurate prediction of solubilities in aqueous solutions is crucial for the geological sequestration of carbon monoxide (CO). This study utilizes the electrolyte version of the Cubic-Plus-Association (CPA) Equation of State to calculate the saturated properties including saturated vapor pressure, saturated liquid-phase density, and saturated vapor-phase density of pure CO, its solubilities in pure water, and its solubilities in aqueous sodium chloride solutions. The model accuracy is validated against experimental data, showing relative average deviations within 3.0 % for saturated liquid-phase density, within 1.0 % for both saturated vapor pressure and saturated vapor-phase density, 4.7 % for CO solubilities in pure water, and 1.3 % for CO solubilities in aqueous sodium chloride solutions. This work not only analyzes the phase behavior of CO in aqueous solutions but also provides an in-depth discussion on the dissolution mechanisms of CO in these solutions. The results demonstrate that the electrolyte version of the CPA Equation of State is a robust model capable of accurately predicting CO solubilities and the complex phase behavior of CO in aqueous solutions across a wide range of temperatures, pressures, and salt concentrations.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"187 ","pages":"Article 106414"},"PeriodicalIF":3.1,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143937062","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":"Decadal transport of trace elements in a cave system based on 16 years monitoring data: Implications for paleoclimate reconstruction","authors":"Xin Fu ,&nbsp;Yan Yang ,&nbsp;Jingyao Zhao ,&nbsp;Yidong Li ,&nbsp;Xiaomin Chen ,&nbsp;Zhimao Ye ,&nbsp;Mingyang Li ,&nbsp;Jingfeng Lin ,&nbsp;Yanzhi Xu","doi":"10.1016/j.apgeochem.2025.106413","DOIUrl":"10.1016/j.apgeochem.2025.106413","url":null,"abstract":"<div><div>The trace element ratios (X/Ca, X = Mg, Sr, Ba) of stalagmites are closely correlated with local hydroclimatic changes and are becoming increasingly important proxies for paleoclimate reconstruction. However, it remains unclear whether the decadal variations in the X/Ca ratios can reflect the signals of the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Variability (AMV) in East Asia. Here, 16 years (2009–2024) of monitoring data on the trace element composition of cave water in Jiguan Cave, located in the middle and lower reaches of the Yellow River in China, were combined with an analysis of X/Ca ratios in stalagmite DSY1201 from the nearby Dongshiya Cave. The primary objective was to comprehensively explore the intricate relationship between the X/Ca ratios and the regional hydroclimatic variations. Our investigation revealed that the decadal changes in the X/Ca Principal Component 1 (PC1) exhibited a significant negative correlation with the PDO. This correlation was likely predominantly caused by the synergistic effects of prior calcite precipitation (PCP), water–rock interaction (WRI), and other factors. Notably, under drought conditions in Jiguan Cave, WRI dominates the hydro-chemical evolution of the cave water, while the reduction in the recharge flux and the prolongation of the water residence time jointly induce a marked enhancement in the X/Ca ratios. Correlation analysis further demonstrated that the PDO significantly modulates the amplitude of the X/Ca-PC1 variability by regulating the frequency of extreme precipitation or drought events during critical years. In addition, the multi-proxy records (X/Ca-PC1, δ¹³C, and δ¹⁸O) from stalagmite DSY1201 revealed similar relationships and patterns in the AMV and PDO phase transitions during the 1960s and late 1990s. Thus, we ultimately suggest that the AMV and PDO play important roles in the decadal variations in the intensity of the East Asian summer monsoon (EASM) and the spatial pattern of the EASM rainfall, in combination with the AMV-Northern Hemisphere (ANH) teleconnection and the Pacific-East Asia (PEA) teleconnection, respectively. This may be recorded by the X/Ca ratios in the karst cave systems in the EASM area.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"187 ","pages":"Article 106413"},"PeriodicalIF":3.1,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143943531","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":"Ligand exchange by As(V) enhanced desferrioxamine B-induced goethite dissolution: Insights into As mobilization in groundwater systems","authors":"Simeng Li ,&nbsp;Wei Xiu ,&nbsp;Xin Liu ,&nbsp;Zhixin Fang ,&nbsp;Jonathan R. Lloyd ,&nbsp;Huaming Guo","doi":"10.1016/j.apgeochem.2025.106412","DOIUrl":"10.1016/j.apgeochem.2025.106412","url":null,"abstract":"<div><div>The dissolution of As-bearing Fe(III) (oxyhydr)oxides is the key process leading to arsenic (As) enrichment in groundwater, which can be enhanced by organic ligands secreted by microorganisms, such as siderophores. However, the roles of organic ligand-induced dissolution of Fe(III) (oxyhydr)oxides in As mobilization are poorly understood. To address this issue, we examined the dissolution kinetics of pure goethite, As(V)-bearing goethite, and As(III)-bearing goethite induced by the trihydroxamate siderophore desferrioxamine B (DFOB) under anoxic conditions and the associated impact of As mobility. DFOB-induced goethite dissolution followed classic surface-controlled dissolution kinetics. As(V) promoted DFOB-induced goethite dissolution, which was attributed to the presence of Fe-As(V) complexes acting as ligand shuttles. However, As(III) slightly inhibited DFOB-induced goethite dissolution, due to the smaller surface area of narrow and rounded (021) crystal facets of As(III)-bearing goethite. Moreover, during DFOB-induced dissolution of As-bearing goethite, the percentages of released As to total As adsorption in DFOB-As(V)-Gt series (13.85 ± 1.52%) were significantly higher than those (9.82 ± 4.66%) in DFOB-As(III)-Gt series, which were linearly positively correlated with goethite dissolution. Therefore, the present findings emphasized the importance of organic ligand-induced dissolution of As-bearing Fe(III) (oxyhydr)oxides as a potential pathway for mobilizing As in groundwater systems.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"187 ","pages":"Article 106412"},"PeriodicalIF":3.1,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143937063","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":"Modelling cadmium binding to plant-based biochars using the three-site NICA-Donnan model","authors":"Yifan Huang ,&nbsp;Gerwin F. Koopmans ,&nbsp;Zhengguo Song ,&nbsp;Rob N.J. Comans ,&nbsp;Liping Weng","doi":"10.1016/j.apgeochem.2025.106404","DOIUrl":"10.1016/j.apgeochem.2025.106404","url":null,"abstract":"<div><div>In this study, generic three-site NICA model parameters for cadmium (Cd) binding to biochars were derived. For this purpose, five biochars prepared from two mixtures of pure cellulose and lignin and maize straw at different pyrolysis temperatures were selected from our previous work to measure Cd binding in batch experiments. This dataset was complemented with data on Cd binding from five other plant-based biochars taken from literature. The three-site NICA model in combination with an electrostatic Donnan model using a constant Donnan volume <span><math><mrow><msub><mi>V</mi><mi>D</mi></msub></mrow></math></span> of 0.1 L kg⁻¹ successfully described the data, covering a wide range in pH and free Cd²⁺ concentration in solution. The model provided quantitative insights into the surface speciation of Cd and the electrostatic interactions between Cd and biochar. Carboxylic- and phenolic-type reactive groups exhibited a lower Cd affinity compared to protons, leading to a strong pH dependency of Cd binding. Cadmium ions bind predominantly as a monodentate complex with carboxylic groups and as mono- and bidentate complexes with phenolic groups on biochar. Although phenolic groups have a higher affinity to bind Cd, carboxylic groups dominate Cd binding due to the smaller difference in the affinity of the latter groups to bind Cd and protons. In addition, the small ionic strength effect on Cd adsorption can be ascribed to the low charge density of biochar and the presence of basic groups (i.e., the third type of sites) on biochar. The basic groups generate positive charge, neutralizing to a certain extent the negative charge generated by the acidic groups, thus weakening the ionic strength effect. Due to this electrostatic effect, ignoring the presence of the basic groups will lead to an overestimation of Cd binding by biochar. In addition to these quantitative mechanistic insights, the derived generic model parameters for the three-site NICA-Donnan model can help to predict Cd binding to unknown biochars over a wide range in pH and ionic strength to support the design of <em>in-situ</em> soil remediation operations.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"186 ","pages":"Article 106404"},"PeriodicalIF":3.1,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143887097","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":"Bulk rock geochemical and mineralogical characterisation of clay-rich sediments from drill core analysis of the Staffelegg Formation","authors":"Marie Bonitz ,&nbsp;Theresa Hennig ,&nbsp;Anja M. Schleicher ,&nbsp;David Jaeggi ,&nbsp;Jessica A. Stammeier ,&nbsp;Christian Ostertag-Henning ,&nbsp;Michael Kühn","doi":"10.1016/j.apgeochem.2025.106389","DOIUrl":"10.1016/j.apgeochem.2025.106389","url":null,"abstract":"<div><div>The long-term integrity of argillaceous formations as host rocks for deep geological disposal of nuclear waste depends significantly on hydrogeological factors. A 58 m long borehole was drilled at the Mont Terri Rock Laboratory (Switzerland) from the Opalinus Clay through the entire underlying Staffelegg Formation, which includes two water-bearing sections. Groundwater was found locally in the Beggingen and Rietheim Members, otherwise known as Gryphaea Limestone and Posidonia Shale, respectively. We want to identify indicators to determine the impact of groundwater flow in clay- and carbonate-rich sediments by characterising mineralogical and geochemical alteration. The groundwater influence is restricted to the water-bearing zones and can be identified by fractures and calcite veins. Additional indicators like mineral assemblage, rock geochemistry and the combination of different redox proxies, show constrained groundwater influence in the clay-rich areas. To investigate in particular the water-bearing horizons on a smaller scale (mm-<span><math><mi>μ</mi></math></span>m) would help to detect further alteration and mobilisation features.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"186 ","pages":"Article 106389"},"PeriodicalIF":3.1,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877492","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":"Uranium(VI) retention by calcium (alumino)silicate hydrates – Impact of temperature and ionic strength","authors":"Katja Schmeide ,&nbsp;Nina M. Huittinen ,&nbsp;Salim Shams Aldin Azzam ,&nbsp;Frank Bok ,&nbsp;Erica Brendler ,&nbsp;Barbara Lothenbach ,&nbsp;Jerome Kretzschmar","doi":"10.1016/j.apgeochem.2025.106400","DOIUrl":"10.1016/j.apgeochem.2025.106400","url":null,"abstract":"<div><div>Calcium aluminosilicate hydrates (C-A-S-H) are the main hydration products of cement formulations with Al-rich additives such as blast furnace slags, fly ashes or calcined clays. We studied systematically the effect of Al substitution on both the structure of C-A-S-H phases and their U(VI) retention properties in comparison to C-S-H phases. To represent the different stages of cement degradation, three series of samples were synthesized, which included samples with Ca/Si molar ratios of 0.8, 1.2 and 1.6 and different Al/Si molar ratios of 0, 0.06 and 0.18 for each series. Furthermore, the impact of synthesis temperature (room temperature, 100 °C, 200 °C) on the C-(A-)S-H structure was studied. The U(VI) retention, studied either by sorption experiments or by direct synthesis of U(VI)-containing C-(A-)S-H phases, was found to be strong with log <em>R</em>_d between 4.9 and 5.6. Structural characteristics of the cementitious phases were obtained from powder X-ray diffraction (XRD) as well as ²⁹Si and ²⁷Al solid-state magic angle spinning nuclear magnetic resonance (SS MAS NMR) spectroscopy. AlO₄ tetrahedra were identified to occupy bridging positions of the silicate chains, thereby increasing the mean chain length and providing additional sorption sites for U(VI) at room temperature. Elevated temperatures during solid phase formation, however, lead to a stronger cross-linking of the silicate chains with the appearance of neoformed crystalline phases. Luminescence spectroscopy was applied to characterize the U(VI) binding. Various U(VI) species (interlayer or surface sorbed) are formed in different proportions, depending on the composition and structure of the C-(A-)S-H phases, which are partly affected by elevated temperatures. To simulate salinity changes of the pore water, the effect of enhanced ionic strengths and the presence of carbonate on the stability of the U(VI) retention by the C-(A-)S-H phases was studied by sorption and leaching experiments over extended timescales of up to 6 months. For C-(A-)S-H phases previously exposed to temperatures of up to 100 °C, the effect of medium ionic strengths (up to 2.6 M) on U(VI) retention was insignificant.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"186 ","pages":"Article 106400"},"PeriodicalIF":3.1,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143898554","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":"Variability of fracture surface roughness in crystalline host rocks: implications for transport model simplifications","authors":"Wenyu Zhou ,&nbsp;Johannes Kulenkampff ,&nbsp;Daniel Jara Heredia ,&nbsp;Thorsten Schäfer ,&nbsp;Cornelius Fischer","doi":"10.1016/j.apgeochem.2025.106401","DOIUrl":"10.1016/j.apgeochem.2025.106401","url":null,"abstract":"<div><div>Variability in fracture geometry and its complex surface characteristics are major contributors to solute transport and retention effects in rocks such as granite. Understanding the effects of cross-scale fracture geometry on solute transport modeling is critical for reliable quantitative predictions in applications such as geothermal energy use and nuclear repository safety. Here, we systematically investigated the sensitivity of fracture surface topography variability to the flow field and solute transport behavior. Specifically, we investigated the role of multiscale fracture surface roughness in solute transport modeling. As a starting point, our study utilized a 3D fracture geometry derived from CT scans and employed COMSOL Multiphysics software for solute transport modeling. By introducing increasingly lower spatially resolved geometries, while maintaining a constant high resolution mesh for simulation calculations, we investigated the consequences for transport on surfaces composed of superimposed building blocks of different sizes and shapes. The results indicate that fracture geometry simplifications with reduced spatial frequency information of well-defined, specific domains do not have a clear trend to alter the BTCs tailing. Instead, this type of model simplification can cause both increased and decreased tracer residence times, leading to misleading interpretations. We explain this by a complex superposition of surface building blocks of different sizes, such as single crystal surface pits, grain boundaries between crystals, and fracture curvature. For model sensitivity analyses, we suggest the use of concentration difference and acceleration maps to identify local transport heterogeneities introduced by geometric simplifications. In addition, we conclude that power spectral density (PSD) analysis provides a means of defining a range of surface spatial frequencies that helps to avoid oversimplification in geometric models of reactive transport.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"186 ","pages":"Article 106401"},"PeriodicalIF":3.1,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870648","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":"Specific responses of minerals during the dissolution of basalt for geological storage of CO2","authors":"Jun-Hwan Bang,&nbsp;Taehee Kim,&nbsp;Soo-Chun Chae,&nbsp;Kyungsun Song","doi":"10.1016/j.apgeochem.2025.106402","DOIUrl":"10.1016/j.apgeochem.2025.106402","url":null,"abstract":"<div><div>Dissolution experiments involving basalt grains (grain size: 0.841–1.190 mm) were conducted under CO₂-saturated conditions to investigate mineralogical changes and fluid chemistry dynamics relevant to geological CO₂ storage. The experiments were initially performed at 35 °C (up to 137 days) and subsequently at 50 °C (up to 210 days). Mineralogical analyses were conducted using scanning electron microscopy with backscattered electron imaging (SEM-BSE), electron probe microanalysis (EPMA), and X-ray diffraction (XRD). The initial dissolution stage was characterized by rapid olivine dissolution, causing substantial early release of magnesium (Mg) and iron (Fe). Labradorite dissolution became increasingly significant after the temperature increase to 50 °C, enhancing mobilization of calcium (Ca), magnesium (Mg), and aluminum (Al). SEM-BSE analyses revealed distinctive dissolution textures on olivine grains, characterized by pronounced Mg depletion and Fe enrichment. Fluid chemistry results reflected these mineralogical changes, indicating rapid initial Mg release, sustained mobilization of silicon (Si) and Fe from ongoing olivine dissolution, and elevated Ca and Al concentrations after temperature elevation due to increased dissolution of plagioclase (labradorite) and, to a lesser extent, augite. Secondary silica precipitation occurred during later reaction stages, inferred from decreasing dissolved Si concentrations. These findings emphasize temperature- and mineral-specific dissolution behaviors, providing critical insights for optimizing basalt-hosted CO₂ sequestration.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"186 ","pages":"Article 106402"},"PeriodicalIF":3.1,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853878","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":"Amendment effectiveness and seasonal variations in a lead contaminated acidic wetland","authors":"Matthew R. Noerpel ,&nbsp;Anna M. Wade ,&nbsp;Aaron R. Betts ,&nbsp;Jennifer Goetz ,&nbsp;Robert Ford ,&nbsp;Amy Krause ,&nbsp;Michael Zeolla ,&nbsp;Diana Cutt ,&nbsp;Stephanie M. Wilson ,&nbsp;Todd P. Luxton","doi":"10.1016/j.apgeochem.2025.106396","DOIUrl":"10.1016/j.apgeochem.2025.106396","url":null,"abstract":"<div><div>Three in-situ lead (Pb) soil amendment treatment methods were tested over 26 months in a naturally acidic contaminated wetland with the intent of sequestering high levels of Pb contamination as stable mineral forms. Two of the treatments used Apatite II, a phosphate-based amendment, to promote the formation of pyromorphite. The apatite amendment was surface applied one method and physically mixed to the surface soils in the other. A sulfate-rich compost-based mixture was used for the third treatment, with the goal to promote the formation of galena. Amendment effectiveness was evaluated by comparison of Pb porewater concentrations between treatments, and by changes in the speciation of sediment Pb as determined by X-ray absorption spectroscopy (XAS). Results show that in the two years following application, the three treatments did not make a significant impact on Pb mobility and speciation. Dissolved Pb concentrations did not decrease significantly in the treatment plots in comparison to the control plots. Furthermore, speciation analysis did not show evidence of pyromorphite formation in the phosphate-amended plots. Galena was found in the third treatment with sulfate-rich compost, however the significance of this was limited by sample size and the presence of galena in other areas of the wetland. There was a seasonal variation in the Pb speciation, with galena and Pb-cysteine being more prevalent at the end of the wet season and less prevalent at the end of the dry season, indicating that while the induced formation of reduced Pb-sulfur species is possible, there are challenges to maintaining those species without concurrent control of soil water saturation. This study shows that effective amendment treatments must account for site-specific characteristics such as pH and redox dynamics, and use appropriate preservation methods for accurate speciation results.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"185 ","pages":"Article 106396"},"PeriodicalIF":3.1,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143839031","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}