Key uncertainties remain in predicting carbon sequestration through enhanced weathering (EW), particularly regarding secondary mineral formation and interactions with the organic matter. We compared a coupled inorganic-organic geochemical model (PHREEQCENTURY) with soil measurements and CO2 efflux from a 389-day mesocosm experiment using soils amended with varying alkaline manure, basalt, and dunite inputs. Silicate amendments did not enhance dissolved inorganic C leaching or significantly increase pedogenic carbonate accumulation. PHREEQC simulations indicated that base cations preferentially precipitated as secondary clays rather than carbonates, inhibiting CO2 removal. Sequential extractions suggested that Al, Fe and base cations were mainly retained via adsorption to (hydr)oxides and organic matter, with additional retention in secondary clays indicated by models. Higher organic matter addition did not increase element release from basalt─and reduced leached K and Fe─while decreasing the reactive surface area of basalt, indicating a counteractive effect of manure on rock weathering. Alkaline manure addition also likely decreased weathering of pyroxene and olivine minerals. Cumulative soil CO2 efflux did not differ significantly among treatments, consistent with PHREEQCENTURY simulations, predicting limited treatment effects due to minor changes in soil pH, moisture and organic C stabilization as mineral-associated organic matter in this soil.

ABSTRACT Elucidating crust–mantle interaction processes during the southward subduction of the Bangong–Nujiang Tethyan Ocean (BNTO) is crucial for reconstructing the tectonic evolution of the Meso-Tethys Ocean. This study focuses on gabbroic dikes exposed in the Yanhu area of Geji County. Zircon U–Pb dating yields crystallization ages of 105.0 ± 2.8 Ma and 109.9 ± 3.1 Ma for the Yanhu gabbros. Geochemically, these mafic intrusions are enriched in large-ion lithophile elements and depleted in high-field-strength elements. They show low 87Sr/86Sr ratios (87Sr/86Sr(i) = 0.704158-0.705377), positive εNd(t) values (+1.29 to +5.89) and zircon εHf(t) values (+3.3 to +9.0), exhibiting the geochemical affinities of arc gabbros with continental sediment contamination. Geochemical modelling indicates that the mantle source of the Yanhu gabbros was derived from depleted mantle mixed with minor upper crustal and ocean island basalt (OIB) components, which subsequently experienced ~22% partial melting. We propose that the Yanhu gabbros formed in response to slab breakoff during the final stage of the southward subduction of the Bangong–Nujiang Ocean. Subduction processes account for the arc geochemical characteristics associated with the incorporation of upper-crustal material. OIB-type mantle materials originated from passive upwelling induced by slab breakoff. Mantle plume activity exerted lingering influences on the mantle beneath the Cretaceous Bangong–Nujiang oceanic basin.

Climate-induced permafrost thaw unlocks large stores of organic carbon that are mineralized and emitted as carbon dioxide (CO2) from rivers to the atmosphere1. Concurrently, warming and permafrost thaw can increase mineral weathering rates, thus affecting the release and sequestration of inorganic carbon2-4. Yet how these biological and geological carbon cycles interact and jointly affect CO2 dynamics (emission compared with drawdown) in permafrost rivers remains unknown5. Here we combine CO2 emissions, organic and inorganic solute concentrations, dual carbon isotopes (δ13C-Δ14C) and geochemical modelling to infer how permafrost thaw may affect river biogeochemistry over decades to centuries across the Qinghai-Tibet Plateau. Leveraging a gradient of thermal permafrost degradation, we find that river CO2 emissions decline, whereas solute fluxes from rock weathering increase with decreasing permafrost cover. Across this region, net CO2 drawdown fluxes from rock weathering are about 35% of river CO2 emissions, varying from around 15% in catchments with continuous permafrost to more than 100% in catchments with discontinuous or isolated permafrost. Thus, carbon fluxes from chemical weathering may become increasingly important with ongoing permafrost thaw, potentially even outpacing river CO2 emissions. Our findings disentangle the interplay between biological and geological carbon fluxes that are important for the cryosphere and the global carbon cycle.

Source characterization of trace elements and impacts of salinization using geochemical modelling with machine learning approach and Monte-Carlo based health risk assessment in coastal aquifer zones.

Fractionation and speciation of rare earth elements in legacy mining lakes using diffusive gradients in thin films (DGT) and single-particle ICP-MS (spICP-MS): From seasonal baselines to extreme atmospheric deposition events.

Habitability of rocky planets relies on the budgets of life-essential elements (LEEs) in their building blocks. The provenance and geochemistry of the planetesimals that supplied the LEEs to Earth remain debated. Traditional models argue LEE delivery via outer Solar System chondrites, but their 2 to 4 million-year (Myr) accretion ages preclude them as the first feedstock. To investigate the initial LEE distribution, we reconstructed the phosphorus-nitrogen (P-N) budget of the iron meteorite parent bodies (IMPBs), which accreted <1 Myr of Solar System formation. High-pressure-temperature experiments of P-N partitioning between solid and liquid alloys combined with geochemical models reveal higher P/N ratios in outer Solar System IMPBs than in inner ones—a trend reversed in chondrites. This evolution reflects early refractory schreibersite delivery to the outer disk, later curtailed by Jupiter’s growth. Further modeling in combination with previous elemental and isotopic data on volatile LEEs suggests that both early and later inner Solar System planetesimals are chief contributors to Earth’s LEE inventory.

Understanding the mechanisms governing radionuclide retention by clay minerals is essential for the long-term safety of geological repositories. This study proposes an operational, multi-criteria assessment framework to interpret the relative contributions of surface adsorption, hydration-state–mediated interlayer uptake (1W→2W transitions), and ion exchange during cesium retention in Wyoming montmorillonite (SWy-2). Rather than relying on any single technique, the framework integrates complementary signatures from batch experiments, X-ray diffraction (used strictly as hydration-state indicators), PHREEQC geochemical modeling, and multilayer statistical-physics fitting. Batch experiments were conducted using both non-radioactive CsCl and 137 Cs across concentrations from 10 -6 to 10 -2 M, pH 4–9, and temperatures of 278–338 K. At trace concentrations (<10 -6 M), cesium retention is consistent with rapid surface adsorption, characterized by short half-lives and strong pH sensitivity. At intermediate concentration (≈10 -4 M), a basal-spacing evolution from 12.5 to 15.2 Å reflects hydration-state transitions accompanying partial Na + /Cs + exchange, supported by slower uptake kinetics and thermodynamic trends. At high concentration (>10 -2 M), ion-exchange signatures predominate, as evidenced by Cs + /Na + selectivity (Kex = 2.8 ± 0.3), Na + release stoichiometry, and persistent 2W domains. Dry-state XRD patterns are interpreted exclusively as hydration-state constraints rather than mechanistic proof, and mechanistic assignments arise only from convergence among kinetic, thermodynamic, structural, and exchange-based evidence. PHREEQC simulations confirm that Cs remains >99.8% as hydrated Cs + across all pH values and that precipitation is thermodynamically unfavorable (SI = –6.22 to –10.21). Statistical-physics modeling reproduces the equilibrium isotherm with R 2 > 0.95 and yields physically consistent layer-site distributions after unit correction. Overall, this integrated approach provides a structured framework for synthesizing multi-signature datasets to interpret cesium retention mechanisms on montmorillonite, while explicitly recognizing the limitations of individual techniques (particularly dry-state XRD) and avoiding over-interpretation of single experimental indicators. • Integrated experimental, XRD, geochemical, and statistical physics approaches to discriminate radionuclide retention mechanisms in montmorillonite • Clear concentration-dependent transition from surface adsorption to intercalation and ion exchange • Quantitative d 001 basal spacing evolution used as a structural fingerprint of intercalation • Kinetic and thermodynamic signatures establish definitive mechanistic criteria • Implications for predictive modeling of radionuclide behavior in geological disposal systems

Water source and quality is the most important factor for region sustainable development, especially in the water-scarce arid agricultural regions. In the agricultural area of arid Qaidam Basin, water quality remains inadequately studied. Focusing on the Xiangride River Watershed in the southeastern Qaidam Basin, this research explores the recharge sources, hydrogeochemical evolution, and quality of river water and groundwater integrating correlation analysis, principal component analysis (PCA), and inverse geochemical modeling. Stable isotopic analysis indicates that river water and groundwater are derived from mountainous precipitation, and groundwater is recharged by lateral runoff and river seepage in the plain area. Most river water and groundwater samples exhibit relatively low TDS values of < 1000 mg/L, and groundwater exhibits more complex hydrochemistry compared with river water. Along the flow path, the hydrochemical types are marked by the HCO3·Cl·SO4-Na·Mg type for river water, which groundwater shows an evolution from Cl·HCO3-Na·Mg to Cl·HCO3·SO4-Na·Ca·Mg and ultimately to HCO3·Cl·SO4-Na·Ca·Mg. The comprehensive analysis by PCA, major ions relationships and inverse geochemical modeling identifies that water-rock interactions including dissolution and precipitation of evaporites, carbonates, and silicates, together with cation exchange and mixing control the hydrochemical compositions. Water quality assessment based on EQWI, SAR, and Na% values classifies most river water and groundwater as "good" without obvious spatial variation, indicating that the overall water quality is adequate for domestic and agricultural uses. The attention needs to be made in certain area with relatively elevated groundwater NO3 -. These findings provide a basis for the sustainable management of water resource in arid agricultural zones.

Spatio-temporal variation in hydrogeochemical characteristics and trace elements occurrence in groundwater in parts of Lakhimpur district, Uttar Pradesh

Abstract Enhancing the durability of cement paste through the incorporation of appropriate additives represents a promising approach to improving the sustainability of cement production. In particular, the inclusion of layered double hydroxides (LDHs) in cementitious systems has been shown to enhance their corrosion resistance to Cl − and SO 4 2− anions. However, LDHs, due to their anionic exchange capability, significantly affect the initial kinetics. In this work, two types of nanometric LDHs, MgAl-NO 3 and MgAl-HCOO, were added to cement paste in different proportions (1, 3, and 5 wt% of the binder) to investigate early hydration kinetics and to quantitatively evaluate the effect of anion exchange on cement hydration products and clinker phase consumption by in situ X-Ray diffraction (XRD). In addition, the chloride binding capacity of selected LDHs was tested by means of XRD and thermogravimetric analyses. The results show that, in the early hydration stage, LDHs can capture SO 4 2 ⁻ ions, thereby inhibiting early ettringite precipitation and enhancing the production of hydration products (portlandite) after the first 24 h. LDHs containing formate decrease the availability of Ca 2 ⁺ in solution, thereby limiting the precipitation of calcium-rich phases, slowing down the dissolution of alite (C 3 S). Geochemical modelling supports these findings. Finally, both MgAl-NO 3 and MgAl-HCOO improved the chloride binding capacity of the cement paste due to their excellent anion exchangeability.

Traditional cementitious materials, primarily based on Portland cement, destabilize in hot, corrosive geo-fluids, impeding the advancement of geothermal systems as a scalable energy solution. Yet, identifying geo-stable alternatives that meet multifaceted performance demands throughout the inherently non-equilibrium structural evolution over geothermal well lifetimes remains a fundamental challenge. Here, we present a cure-to-service cement design principle that orchestrates the co-evolution of mechanical properties, phase development and permeability from initial cure through prolonged service, confining metastability by decoupling early-stage Al/Si release to enforce a controlled reaction toward stable aluminosilicate forms. In this design, coarse-grained silica embeds within the nascent boehmite matrix to mitigate permeability, wherein the alkali activator acts as a kinetic lever steering phase selection along the non-equilibrium crystallization pathway. In-situ synchrotron XRD and geochemical modeling show preferential Al dissolution and rapid boehmite formation, while delayed Si availability suppresses premature intermediate formation. Under exposure to supercritical H2O, analcime serves as a Na+ reservoir whose gradual dissolution feeds Na-rich phyllosilicates (e.g., paragonite). The nascent composite gains strength and toughness while maintaining low permeability as metastable species convert to stable phases through staged crystallization. This work defines a design principle of aluminosilicate-based cementitious systems for extreme subsurface applications.

Arsenic (As) adsorption onto ferrihydrite (Fh) is an effective method for reducing As concentrations and is commonly used in passive mine drainage treatment. A model that predicts the removal of As(III) and As(V) is essential for designing treatment conditions. In this study, the mechanism of As removal in an As(III)-As(V) coexisting system by Fh at pH 7 was clarified. The presence of As(V) inhibited the surface complexation of As(III) on Fh. X-ray absorption fine structure (XAFS) analysis showed that surface precipitation of FeAsO4 was suppressed at a low As/Fe ratio, while the proportion of surface-complexed As(III) increased. A geochemical model incorporating surface complexation and precipitation of As to Fh was developed using PHREEQC and reproduced experimental results by adjusting the solubility product (Ksp) of FeAsO4 according to the As/Fe ratio. This model also reproduces the arsenic removal behavior observed at sites where As removal by Fh generation is being attempted. Because this model is based on equilibrium reactions, to manage field treatment using model predictions, it is desirable to avoid conditions where Fh redissolution and reprecipitation occur, and to design a hydraulic residence time (HRT) of 10h or more.

Manganese (Mn) plays an important role in marine biogeochemical cycling; however, the mechanisms of microbial Mn oxidation in deep-sea environments remain poorly understood. This study investigated the Mn tolerance and precipitation capabilities of a novel bacterial isolate, Staphylococcus ureilyticus GOM10, isolated from deep-sea water in the Gulf of Mexico. Using a multidisciplinary approach combining microbiological, microscopic, spectroscopic, genomic, and geochemical modeling techniques, we elucidated the genetic pathways underlying Mn oxidation in GOM10. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed the presence of Mn-bearing precipitates associated with the bacterial cells. The strain demonstrated tolerance to Mn(II) concentrations up to 150 mM and could oxidize Mn(II) at a rate of 5.2–29.2 nM h−1. Genomic analysis revealed genes related to Mn transport and oxidation, including superoxide dismutase (SOD), peroxidases, and Mn-dependent regulators, suggesting that the Mn oxidation mechanism involves the generation of reactive oxygen species (ROS). The proposed oxidation pathway couples Mn(II) oxidation with cellular protection against oxidative stress. Our findings highlight the importance of investigating alternative pathways, such as ROS-mediated oxidation, for a more comprehensive understanding of Mn biomineralization in deep-sea environments. This study provides insights into microbial adaptations in deep-sea environments and the potential role of heterotrophic bacteria in Mn cycling.

Groundwater quality in arid and semi-arid regions is under increasing pressure from both natural and anthropogenic sources. This study presents a comprehensive assessment of groundwater quality in the Gonbad Plain, Iran, to determine its suitability for drinking and to identify the controlling hydrogeochemical processes. A total of 45 groundwater samples were analyzed for their physicochemical parameters, and the data were evaluated using an integrated approach combining hydrochemical facies analysis, geochemical modeling (PHREEQC), multivariate statistical techniques (Principal component analysis (PCA) and hierarchal cluster analysis (HCA)), and human health risk assessment (Heavy metal pollution index (HPI), Hazard quotient (HQ), Hazard index (HI)). The results reveal a hydrochemical evolution from fresh Ca-HCO₃ type water to saline Na-Cl type water, primarily controlled by three key mechanisms: (1) dissolution of evaporite minerals (halite and gypsum), (2) cation exchange, and (3) evaporation. The Gibbs diagrams confirmed that rock-water interaction and evaporation are the dominant processes governing water chemistry. Iron concentrations varied from 0.01mg/L to 4.12mg/L, with a mean of 0.46mg/L and a standard deviation of 0.66mg/L. The median iron concentration was 0.27mg/L. Manganese concentrations ranged from 0.015mg/L to 0.47mg/L, with a mean of 0.09mg/L and a standard deviation of 0.07mg/L. The median manganese concentration was 0.08mg/L. The HPI indicated a critical water quality crisis, with 77.8% of the samples being unsuitable for drinking (HPI > 100), primarily due to elevated concentrations of manganese. The non-carcinogenic health risk assessment revealed that while the dermal exposure pathway poses no significant risk, oral ingestion of groundwater presents a potential health hazard, particularly for children. The HI exceeded the safe limit of 1.0 in 11.1% of the samples for children, with manganese being the primary contributor to the risk. This is the first study apply integrated framework that combines multivariate statistics, geochemical modeling, and health risk indices to evaluate groundwater vulnerability in Gonbad-e Kavus. The study's alignment with UN Sustainable Development Goal 6 (Clean Water and Sanitation).

From TTG-migmatized to crustally-derived granites: Evidence of partial melting and reworking during the Mesoarchean crustal evolution in the southeastern Carajás Province (Amazonian Craton, Brazil)

Integrated hydrochemical and geochemical modeling of cadmium migration and source apportionment in shallow groundwater

Geochemical modeling of rare earth element adsorption onto aluminum hydroxide and hydroxysulfate under variable sulfate conditions.

Natural and anthropogenic controls on rare earth elements in groundwater: Indicative significance for distinguishing agricultural and urban-industrial impacts.

Carbon mineralization in basaltic rocks offers a promising pathway for rapid, permanent CO2 storage, yet fundamental controls on reactive transport, precipitation patterns, and permeability evolution under seawater conditions remain poorly constrained. This study integrates flow-through column experiments at 80 °C with CO2-acidified seawater, geochemical modeling, and multiscale pore imaging (SEM-EDS and micro-CT) to elucidate mineralization dynamics in basaltic glass. Results demonstrate that carbonate precipitation is nucleation-limited and kinetically controlled rather than thermodynamically driven or growth-dominated, forming discrete patchy accumulations despite sustained supersaturation. An order-of-magnitude reduction in flow rate (0.05 to 0.005 mL/min) was required to achieve visible precipitation, highlighting residence time as the primary control. Postexperiment characterization identified calcium carbonate and inferred smectite-like clays, with dissolution-induced surface roughening and localized precipitation evident across the column. Seawater chemistry further complicates mineralization kinetics and efficiency relative to freshwater systems. Micro-CT analysis of three vesicular basalt facies revealed low coordination numbers (modal = 2) and serial connectivity, contrasting sharply with higher-coordination sandstone networks. The connected porosity (1.3-32%) differs significantly from the total segmented porosity (18-42%), demonstrating that network topology, rather than total porosity, controls permeability. Pore-scale observations thus indicate that precipitation may render basalts inherently more vulnerable to permeability impairment from modest, distributed precipitation. We explore end-member precipitation-induced clogging scenarios in which small, distributed precipitates cause disproportionately severe permeability loss compared to large, isolated masses. These findings underscore the need for probabilistic reactive transport frameworks that incorporate realistic pore topologies and nucleation barriers, which are fundamentally different from conventional CCS in sedimentary reservoirs, to improve predictions of injectivity and long-term carbon mineralization performance in mafic formations.

The arid alpine landscape on the northern margin of the Qaidam Basin, northern Tibetan Plateau, presents a challenge for conventional geochemical background modeling. Leveraging a unique multi-scale geochemical dataset (1:200 000, 1195 samples; 1:50 000, 18 855 samples; 1:25 000, 35 675 samples) from the Qinghai Geological Exploration Fund, this study systematically evaluates scale effects on background estimation. We compared the performance of four prevalent methods – iterative exclusion, median absolute deviation, exploratory data analysis, and the concentration–area fractal method – and found that a multi-method approach effectively balances the comprehensiveness and precision of the background modeling framework. To address the spatial heterogeneity of backgrounds caused by complex geology, we propose a novel subzone robust background method (SRBM). This method calculates robust median background values within distinct geological units and generates an adaptive background field through area-weighted fusion. In the Banhongshan area, application of the SRBM precisely calibrated the gold background to 0.47 ng g −1 , successfully identifying two concealed gold anomalies obscured by traditional methods; one anomaly coincides perfectly with known industrial orebodies. This research demonstrates that high-density sampling (1:25 000) significantly enhances the signal-to-noise ratio for chalcophile elements in arid alpine terrains. The SRBM, by integrating geological knowledge with robust statistics, provides a powerful and reliable tool for weak geochemical signal extraction in both mineral exploration and environmental assessment.