The efficient extraction and enrichment of uranium from wastewater using porous membrane is significant for pollution control and resource recovery. However, porous membrane prepared by conventional methods often suffer from poor environmental compatibility, structural instability, and declining separation efficiency and flux. This study proposes a green strategy for fabrication of high-performance porous uranium separation membranes via Pickering foam templating. 1.0 wt% nano-palygorskite (Pal) was optimized as the foam-stabilizing particle and 0.1 wt% Sapindus saponin (Sap) as the green foaming agent to formulate a Pickering foam film-forming solution within sodium alginate (SA) matrix. After casting and cross-linking yielded a membrane (Pal/Sap/SACa) featuring stable interconnected porous network, enabling precise anchoring of uranium-capturing functional groups on pore surfaces and within network. Under conditions of pH 4.7-5.7 and solid-liquid ratio 0.50 similar to 0.75 g/ L, the membrane achieved a uranium adsorption capacity of 216 mg/g and a removal rate of 95 %, leveraging synergistic coordination and ion exchange. Dynamic extraction experiments showed that using a double-layer membrane to treat a solution with uranium concentration of 8.0 x 10-4 mol/L (flow rate 0.5 mL/min) resulted in a cumulative uranium extraction rate (CR3) and enrichment rate of 91 % and 92 %, respectively. Furthermore, a functionally enhanced membrane obtained via nitric acid-catalyzed esterification exhibited a 50 % increase in initial extraction efficiency compared to Pal/Sap/SA-Ca membrane, and CR3 rising to 96 %. This enhanced membrane was reusable for at least 6 cycles, achieving 5-fold uranium enrichment. This study provides a feasible technical pathway for applying green-constructed porous membrane in uranium pollution control and resource recovery.

The safe disposal of high-level radioactive waste(HLW) is a critical challenge for the sustainable development of nuclear energy globally. Deep geological disposal, internationally recognized as a viable solution, aims to isolate HLW over long timescales(up to millions of years) through a multi-barrier system. This paper focuses on the long-term alteration of the host rock in the near-field of a deep geological repository and its prolonged impact on the geochemical environment and radionuclide migration behavior. After repository closure, the surrounding granite will undergo continuous alteration due to combined effects of decay heat, groundwater-rock interaction, ionizing radiation, and microbial activity. These alteration processes may modify the physical properties of the rock mass(e.g., pore structure, permeability, and fracture connectivity), potentially reshaping groundwater flow paths and radionuclide transport routes. Simultaneously, the dissolution of primary minerals and precipitation of secondary phases can alter the chemical conditions of the near-field groundwater. Furthermore, rock alteration may change mineral surface properties such as sorption sites, surface charge, and reactivity, and promote the generation and long-term evolution of colloids. These physicochemical changes complicate radionuclide migration, affecting diffusion and advection mechanisms within altered fracture networks and the rock matrix. From the perspective of long-term host rock alteration, this study investigates the migration, transformation, and fate of radionuclides following the closure of a deep geological repository.

Legacy heavy metal pollution from historical mining restructures sediment microbial composition and function directly impacting contaminant fate and ecosystem health. The Dongdagou stream (Baiyin, China) possesses a pronounced geochemical gradient caused by long-term discharge of potentially toxic metals including Cd, Cu, Pb, and Zn. We employed this natural gradient to characterize microbial taxonomic and functional responses to metal stress. Sediment samples from four zones along the contamination gradient were analyzed for geochemistry, metal concentrations, and microbial composition (bacteria, archaea, and fungi) via high-throughput amplicon sequencing, with functional potential inferred using PICRUSt2. We found that microbial community structure and function were primarily shaped by metal concentration, with db-RDA explaining 18.1%, 12.4%, and 12.9% of the variance for bacteria, archaea, and fungi, respectively. Cadmium was identified as the strongest individual predictor for both bacterial (r2 = 0.50, p = 0.001) and fungal (r2 = 0.38, p = 0.001) communities. Bacterial diversity increased significantly downstream as contamination declined, with Shannon diversity increasing from 5.17 in the Source Zone to 6.28 in the Distal Zone (Tukey’s multiple comparison test, p < 0.05). Upstream sediments were dominated by metal-tolerant taxa such as Sulfurifustis (17.4%) and Acidithiobacillus (5.0%), while downstream taxa shifted to heterotrophic genera like Gallionella (4.8%) with diverse metabolic capabilities. Despite cadmium being a key predictor, archaeal and fungal communities demonstrated greater compositional stability than bacteria, as shown by their lower beta-dispersion (ANOSIM R = 0.3152 and 0.5762, respectively, compared to 0.7222 for bacteria), indicating potential functional redundancy. Metagenomic predictions revealed a significant enrichment of genes for metal detoxification, anaerobic respiration, and oxidative stress response in polluted zones. These findings establish that microbial communities are both sensitive bioindicators and key mediators of contaminant dynamics, providing a framework for using microbial signatures to assess sediment health and monitor remediation efficacy.

Interactions between iron minerals and dissolved organic matter (DOM) are ubiquitous across environmental systems, but the global effects of photochemical synergies between DOM and iron minerals in surface environments remain to be comprehensively elucidated. Contrary to the assumption that minerals primarily stabilize organic matter, iron minerals also control the release, conversion and mineralization of associated organic carbon through dissolution, phase evolution and photo-oxidation. Concurrently, DOM modulates the photoreduction, transformation and reactivity of iron minerals via light-mediated electron transfer and photochemically generated reactive oxygen species. These mineral–organic interactions are shaped by environmental variables and molecular characteristics that exert a marked influence on the mobility, speciation and transformation of associated contaminants, particularly at dynamic environmental interfaces. This Review focuses on the reactivity, vulnerability and spatial heterogeneity of iron and carbon pools in response to solar radiation and provides an update on how light shapes the coupling of iron and carbon cycles in terrestrial and aquatic surface systems. Field observations integrated with laboratory experiments, and advanced analytical techniques could enable the photochemistry of iron minerals and DOM to provide a framework for improved understanding of the biogeochemical cycling of iron, carbon and contaminants, refining carbon budgets and informing sustainable remediation strategies. Iron minerals and dissolved organic matter contribute to elemental cycling, contaminant dynamics and biogeochemical processes. This Review provides an update on iron mineral–dissolved organic matter photochemistry and highlights research priorities that could improve climate model predictions, the accuracy of carbon budgets and understanding of contaminant behaviour under sunlight.

Iron (oxyhydr)oxides serve as critical substrates for uranium sequestration in environmental systems. However, the immobilization behavior of U(VI) by co-precipitates of Fe(II)/Fe(III) at moderate molar ratios remains unclear. This study investigates phase evolution during Fe(II)/Fe(III) co-precipitation and subsequent U(VI) immobilization mechanisms. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses revealed that co-precipitates with a low Fe(II)/Fe(III) molar ratio (1:50) retained as the phase of ferrihydrite for 48 h, whereas those with a high Fe(II)/Fe(III) molar ratio (1:10) transformed to goethite within 12 h. Acid dissolution experimental results are consistent with Fe(II) being incorporated throughout the bulk of the precipitate particles. The accelerated U(VI) immobilization kinetics in the Fe(II)/Fe(III) ratio of 1:10 system may be attributed to the enhanced surface reactivity of goethite as its dominant crystalline phase. Combined density functional theory (DFT) and spectroscopic analysis reveal a critical energy barrier that inhibits electron transfer from structurally incorporated Fe(II) to U(VI) at low Fe(II) density. Integrating these findings with literature evidence of U(VI) reduction in magnetite (Fe(II)/Fe(III) ≈ 1:2) supports the proposed concept of a reductive inert threshold for structural Fe(II), bracketed between ratios of 1:10 and 1:2. In contrast, supplementation with high concentrations of aqueous Fe(II) induced partial reduction, highlighting the critical role of Fe(II) speciation and availability. This finding reveals a non-reductive, adsorption-dominated immobilization pathway for uranium at the iron oxide interface, which improves the theoretical understanding and provides a new foundational basis for evaluating and predicting the environmental behavior of uranium.

Metallurgical technology has been a fundamental driver in the evolution of Chinese civilization. Established heavy metal records suggest its introduction into northwestern China occurred around 4000 years ago. However, this timeline is difficult to reconcile with evidence for earlier metallurgical developments documented in other regions of China. This study presents a 12-kyr record of heavy metal pollution and anthropogenic activities, reconstructed from geochemical element concentrations and Pb isotope ratios in the sediments of Hurleg Lake on the northeastern Tibetan Plateau (NE TP). The excess Pb and Cu records reveal the earliest anthropogenic heavy metal pollution occurred at approximately 6.3 cal kyr BP, as supported by a concomitant depletion in 206Pb/207Pb ratios. Furthermore, triple isotope plots identify that the Pb pollution sources in Hurleg Lake sediments were primarily derived from ore mining/metallurgy within the Tibetan Plateau and the Hexi Corridor. Two pronounced periods of heavy metal pollution were identified on the NE TP and Hexi Corridor during 6.3-5.1 cal kyr BP and 4.8-3.4 cal kyr BP, respectively. The first period of intensified pollution on the NE TP coincides with a local warm-wet climate phase. Conversely, the subsequent cold-dry interval (4.8-3.4 cal kyr BP) on the NE TP likely prompted a human migration to the lower-altitude Hexi Corridor, which offered more favorable living conditions. A broader analysis of heavy metal profiles across China identifies five distinct pollution peaks during the Holocene. These findings indicate that metallurgical development in the northwestern region not only predated that of other regions but also potentially predated the previously established timeline of 4000 years. A notable increase in heavy metal concentrations from 4.2 to 2.6 cal kyr BP observed across China was contemporaneous with the archaeologically defined Chinese Bronze Age. This study provides key evidence for the spatiotemporal diffusion of early metallurgical technology within China. It also establishes that sedimentary archives can reliably detect Holocene heavy metal emissions linked to prehistoric and Bronze Age metallurgy. (c) 2026 China University of Geosciences (Beijing) and Peking University. Published by Elsevier B.V. on behalf of China University of Geosciences (Beijing). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Photocatalytic separation of uranium presents a promising approach for resource recovery, yet its efficiency remains limited by severe charge-carrier recombination. Integrating piezocatalysis with photocatalysis offers an attractive pathway to overcome this barrier. Herein, a Type-II CdS@BaTiO3 heterojunction was fabricated by growing CdS nanoparticles onto a BaTiO3 matrix, which enables efficient piezo-photocatalytic uranium extraction. The built-in electric field of the heterojunction, reinforced by the stirring-induced piezoelectric polarization of CdS@BaTiO3, drives directional charge migration and greatly enhances carrier separation. As a result, CdS@BaTiO3 achieved 98% uranium removal within 10 min under stirring and light irradiation, which was 2.5 and 8.3 times higher than those achieved by photocatalysis and piezocatalysis alone, respectively. The composite also delivers a high uranium separation capacity of 1893.2 mg & centerdot;g-1, exceeding most previously reported piezo-photocatalytic uranium extraction systems. Mechanistic investigations identify superoxide radicals (& centerdot;O2-) as the dominant reactive species responsible for U(VI) reduction and immobilization. This work demonstrates a promising water-flow-driven energy-coupling strategy for uranium extraction.

Photocatalytic reduction of U(VI) is a promising approach for the treatment of uranium-containing solutions and resource recovery. However, due to the low charge transfer efficiency and the weak ability to activate dissolved oxygen, most photocatalysts are unable to reduce U(VI) under ambient air conditions, limiting the practical application of this approach. In this study, nano-hollow cubic NiCo-layered double oxide (NiCo-LDO) was prepared using Ni2+-etched ZIF-67 as a precursor and was employed for the photocatalytic reduction of U(VI). Within 180 min of illumination, the NiCo-LDO achieved a U(VI) removal efficiency of 98.0% under ambient air conditions, which is 2.5 and 4.2 times higher than those of NiO and Co3O4, respectively. The efficiency of U(VI) removal remained above 98% after five cycles of reuse. Benefiting from uniformly dispersed heterojunctions and the oxygen vacancies, NiCo-LDO exhibits efficient separation of photogenerated charge carriers. Furthermore, the increased d-band center and hollow cubic structure effectively enhance its adsorption for U(VI) as well as the activation of dissolved oxygen. Together, these features promote electron transfer and oxygen activation, enabling the efficient U(VI) reduction under ambient air conditions. These findings offer implications for designing catalysts applicable to the photocatalytic reduction of U(VI) in practical scenarios.

Iron (Fe)-manganese (Mn) co-precipitated (hydr)oxides (Fe-MnOx) are widespread in natural environments and play a crucial role in controlling uranium (U) migration and speciation. However, the formation of Fe-MnOx and their differences in U(VI) adsorption compared with single-phase ferrihydrite (Fhy) remain poorly understood. Here, the formation process of Fe-MnOx and its U(VI) immobilization were systematically investigated and compared with Fhy. Fe-MnOx exhibits a heterogeneous core-shell structure with a Mn-enriched surface and an Fe-rich core, with similar to 90% of Mn transferred to the solid phase and the Fe-2(+)/Fe3+ ratio in the core rising with acidity. The structure largely retains a Fhy-like framework while providing more complex surface chemistry and higher reactivity. Fe-MnOx exhibits a larger specific surface area and higher U(VI) adsorption capacity than Fhy, with adsorption approaching 100% across pH 5.6-8.6. Environmental factor analyses indicate that solution pH is the dominant factor controlling U(VI) adsorption, while humic acid, solid-to-liquid ratio, ionic strength, and coexisting ions play secondary roles. Spectroscopic evidence confirms that U(VI) is predominantly immobilized via inner-sphere complexation with surface Fe-O and hydroxyl groups, while Mn species on Fe-MnOx surface provide additional adsorption sites, enhancing U(VI) adsorption. Desorption experiments show higher U(VI) release for Fe-MnOx (similar to 15 -20%) than for Fhy (similar to 10%), indicating a dynamic retention behavior and potential risk of remobilization under changing environmental conditions. These findings demonstrate that Fe-MnOx are important for the natural attenuation of U, significantly influencing its environmental behavior and potential long-term stability.

Helium (He) is an indispensable strategic resource for global high-technology industries, and its migration and preservation during accumulation are strongly governed by synergistic interactions with fluid carrier gases such as methane (CH4), carbon dioxide (CO2), and nitrogen (N2). To elucidate the microscopic coupling mechanisms between He and carrier gas molecules, as well as their environmental dependence, this study employs quantum chemical calculations combined with molecular configuration screening to systematically evaluate coupling energies and the stability of He-carrier coupled structures under anhydrous and hydrous conditions. The results show that, under anhydrous environments, the coupling affinity between He and carrier molecules follows the order CO2>CH4>N2>He. In contrast, under hydrous conditions, the interactions of He with CO2 and CH4 are weakened, whereas the coupling stability with N2 is significantly enhanced, accompanied by a spatial reorganization of coupling sites. Solvation effects induced by water molecules strengthen He–N2 interactions, indicating that pore water within mineral matrices facilitates the co-existence of He and N2. In multi-molecular systems, He–H2O complexes exhibit the highest stability, followed by He–CO2, He–CH4, and He–N2. Moreover, owing to their relatively large molecular sizes and their propensity to form molecular clusters, carrier gas molecules can physically block caprock pore throats, thereby enhancing sealing efficiency and reducing He leakage. Based on these findings, three key microscopic contributions of carrier gases to He accumulation are identified, namely aggregation in water, cooperative transport through fractures, and effective retention by caprocks. From a molecular-scale perspective, this study reveals the cooperative role of the He-carrier system in helium accumulation and provides a theoretical basis for elucidating accumulation mechanisms and predicting He-rich sweet spots.

Graphene oxide (GO) exhibits highly tunable oxidative reactivity arising from the interplay between oxygen functionalities and vacancy defects. Here we demonstrate that thermal engineering of these active sites drives a fundamental transition between two intrinsic oxidation pathways on GO. Moderately oxidized sheets (C/O < similar to 7.2), dominated by -OH/-COOH groups, promote light-driven interfacial reactions, whereas strongly reduced, vacancy-rich GO (C/O similar to 21.3) enables efficient dark oxidation, as revealed using As(III) as a molecular reaction probe. The defect-enriched material achieves nearly complete conversion within 10 h without irradiation, indicating a vacancy-mediated chemocatalytic regime. Photoelectrochemical analyses associate the photocatalytic behavior of oxygenated GO with enhanced charge separation, while EPR and scavenger experiments identify center dot OH and H2O2 as the predominant reactive oxygen species across both regimes. Density functional theory calculations further show that vacancies markedly strengthen O-2 adsorption and lower the free-energy barriers for H2O2/center dot OH formation relative to pristine or merely oxygenated basal planes, establishing vacancies as highly competent centers for O-2 activation. The defect-mediated reactivity remains stable across a broad pH range and persists in natural water. By quantitatively correlating active-site distributions with distinct oxidative pathways, this work elucidates the structure reactivity relationships governing GO-based carbocatalysts and provides mechanistic insight into the oxidative behavior of graphene derivatives in aqueous environments.

Cytochrome c (Cyt c), a c-type heme protein commonly found in anaerobic microbial systems, plays a vital role in the extracellular electron transfer. This study systematically investigated the interactions among Cyt c, ferrihydrite, and U(VI) under anaerobic conditions, which is essential for understanding redox transformation mechanisms of elements and minerals in subsurface environments. The results demonstrate that Cyt c undergoes oxidation by directly transferring electrons to ferrihydrite, leading to the partial reduction of ferrihydrite and inducing the crystallization transformation into goethite. Meanwhile, the heme Fe2+ in Cyt c serves as a dominant electron donor for the reduction of U(VI) to insoluble U(IV) (UO2). In the presence of ferrihydrite and U(VI), the adsorption of Cyt c on ferrihydrite modulates electron transfer efficiency, whilst ferrihydrite exhibits dual functionality as an electron acceptor and adsorbent for U(VI). Further, the reduced ferrihydrite-Fe2+ participates in U(VI) reduction through the pathway of secondary electron transfer. Although U(VI) could reduce the adsorption of Cyt c on ferrihydrite to some extent, soluble Cyt c still enhances the generation of ferrihydrite-Fe2+ and accelerates the mineralization of U(VI). Extrapolating to microbial systems, these findings imply that intracellular cytochromes in anaerobic microorganisms may drive similar pathways, wherein biogenic electron transfer proteins and iron minerals cooperatively mediate U speciation, mobility, and mineral transformation. This work advances the understanding of microbially mediated redox processes governing the cycle of elements and mineral transformation in anoxic environments.

Laccase offers an efficient and environmentally friendly catalytic pathway for pollutant degradation, yet its practical application is constrained by its sensitivity to environmental conditions. In this study, Trametes versicolor laccase was immobilized and cross-linked onto biochar to construct a functional biocatalytic material for the degradation of high-molecular-weight polycyclic aromatic hydrocarbons (PAHs). The immobilized laccase, particularly wheat biochar-immobilized laccase (W700-ILC) and corn biochar-immobilized laccase (C700-ILC), exhibited significantly greater stability than the free enzyme across pH 5-8, salinity 0.1-0.3%, and 25-35 degrees C. Under optimal conditions (1 mM ABTS or HBT, pH 5.0, 30 degrees C), W700-ILC and C700-ILC achieved removal efficiencies of 75.42% and 84.35% for pyrene (PYR), and 78.17% and 93.82% for benzo[a]pyrene (BAP), respectively, while retaining similar to 80% activity after five reuse cycles. Molecular docking suggested that PAHs preferentially bind to surface crevices rather than directly entering the catalytic pocket, and indicated differences in interaction behavior between BAP and PYR. GC-MS (Gas Chromatography-Mass Spectrometry) analysis further suggested that PAH transformation in the biochar-immobilized laccase system may involve radical-mediated reactions, including ring opening, molecular rearrangement, and progressive breakdown, with the incorporation of exogenous nitrogen and oxygen species. Compared with previously reported biochar-immobilized laccase systems, this study features a composite immobilization design, improved stability under variable conditions, and preliminary evidence for the transformation behavior of high-molecular-weight PAHs. These results may provide a basis for further evaluation of biochar-immobilized laccase in more complex environmental matrices and under longer-term operating conditions.

Geological hydrogen plays a crucial role in Earth’s energy and material cycles, significantly influencing the evolution of the Earth’s spheres and the formation of key mineral resources. Abiotic hydrogen has become the focus of geological hydrogen research due to its broad sources and speculative abundance. However, there remains a lack of consensus on the sources, contributions, and dominant factors in abiotic geological hydrogen formation. A systematic review indicates that abiotic geological hydrogen is primarily generated through three pathways: hydrothermal reactions of Fe(II)-bearing minerals, water radiolysis, and radical reactions at the mineral-water interface. Their respective estimated generation rates of 0.2×1011–6.3×1012 mol/year, 1.6×1010–1.35×1013 mol/year, and 1.1×108–2.5×1010 mol/year. The core mechanism of Fe(II)-bearing mineral-water reactions involves electron transfer from Fe(II) and mineral phase transformation, a process strongly temperature-dependent. Water radiolysis generates hydrogen through free radical generation induced by radioactive irradiation, influenced by radiation type and dose. Additionally, freshly exposed mineral surfaces can generate hydrogen via free radicals formed from interfacial water molecules at unsaturated coordination sites—a process controlled by mineral type. These reactions are collectively regulated by geological environmental conditions, such as aqueous chemistry and atmospheric composition. This review provides an overview of the three primary formation mechanisms of abiotic geological hydrogen, and discusses the key geochemical factors that control these processes. Finally, it identifies current research gaps concerning the mechanisms, influencing factors, and resource assessment.

Uranium (U) contamination poses a significant environmental threat due to its mobility, radiotoxicity, and persistence in water bodies near mining and ore-processing sites. In sulfidic and anoxic conditions common to these settings, the sulfidation of iron (hydr)oxides may play a key role in the transformation and immobilization of U(VI) and iron (hydr)oxides, yet the mechanisms remain poorly understood. In this study, we systematically examined the reaction mechanisms between U(VI) and ferrihydrite in the presence of S2- under anaerobic conditions. The sulfidation can indeed induce pronounced structural and chemical alterations of ferrihydrite, including reductive dissolution and the release of Fe2+, leading to the formation of reactive mineral phases (goethite, hematite, and mackinawite) and surface sites. Notably, the mineral transformation pathways were pH-dependent, at pH 7, the system favored the formation of more crystalline and thermodynamically stable phases such as hematite and goethite, whereas poorly crystalline phases and higher concentrations of dissolved Fe2+ dominated the transformation products under pH 5 conditions. These formation processes of newly formed iron mineral phases promoted the reductive conversion of aqueous U(VI) to insoluble U(IV), with Fe2+ acting as an effective secondary reductant. The co-evolution of iron and U species highlights a tightly coupled redox and sorption process that governs U(VI) immobilization and ferrihydrite transformation. Furthermore, the dynamic transformation of ferrihydrite under S2- influence reveals key mineralogical pathways that contribute to U retention in reducing environments. It is noted that the oxidation of S2- was a stepwise process experiencing S0, SO32-, and finally SO42-. Our findings provide novel mechanistic insights into how sulfur-driven processes modulate U behavior through interlinked mineral and redox dynamics. This work offers a scientific basis for developing passive remediation strategies that leverage natural biogeochemical processes to stabilize U in contaminated waters.

Bacillus subtilis exhibits a great affinity to soluble U(VI) through non-reducing biomineralization. The pH value, temperature, initial uranium concentration, bacterial concentration, and adsorption time are recognized as the five environmental sensitive factors that can regulate the degree of non-reductive biomineralization. Most of the current studies have focused on the regulatory mechanisms of these factors on uranium non-reductive mineralization. However, there are still few reports on the importance of these factors in influencing non-reductive mineralization, as well as on how to regulate these factors to increase the efficiency of non-reductive mineralization and enhance the enrichment of Bacillus subtilis on uranium. In this work, a deep learning neural network model was constructed to effectively predict the effects of changes in these five environmental sensitivity factors on the non-reducing mineralization of Bacillus subtilis to uranium. Accuracy (99.6%) and R2 (up to 0.89) confirm a high degree of agreement between the predicted output and the observed values. Sensitivity analysis shows that in this model, pH value is the most important influencing factor. However, under different pH values, temperature, initial uranium concentration, adsorption time, and bacterial concentration have different effects. When the pH value is lower than 6, the most important factor is temperature, and once the pH value is greater than 6, the initial concentration is the most important factor. The results are expected to provide a theoretical basis for regulating the enrichment degree of U(VI) by Bacillus subtilis, achieving the maximum long-term stable fixation of U(VI), and understanding the environmental chemical behavior of uranium under different conditions.

Polymeric carbon nitride (CN) faces challenges in photocatalytic applications for uranium separation and enrichment from water due to its fast carrier recombination and insufficient light absorption. Herein, we simply introduced phosphorus (P) dopant into CN units (PCN), enabling efficient photocatalytic removal of hexavalent uranium (U(VI)) from aqueous solution. The doping of electron-rich P atom well-tuned the electronic structure and photochemical response of CN, delivering a narrower band gap for enhancing its carrier transfer. Density functional theory (DFT) calculations revealed the introduction of impurity levels after P doping, enabling easier band-gap transition of photogenerated electrons for hexavalent uranium (U(VI)) reduction. The optimized PCN achieved a high U(VI) removal efficiency close to 100 % within 20 min illumination when using methanol as a sacrificial agent, with corresponding removal rate (0.306 min- 1) being 10 times higher than that of pristine CN (0.031 min- 1). Moreover, the generated center dot O2- radicals played a pivotal role in photocatalytic reduction process. U (VI) was finally reduced as insoluble UO2+x deposited on PCN surface. These findings suggest a new direction for sustainable and efficient uranium resource recycling.

Photocatalysis offers a promising method for uranium extraction from seawater. However, the conventional photocatalytic reduction pathway faces challenges due to the adverse effects of oxygen and carbonate under ambient conditions. In this study, an S-scheme heterojunction is constructed by loading TiO2 onto tubular graphitic carbon nitride (PCN) for the photocatalytic U(VI) extraction. The photogenerated electrons from the conduction band of TiO2 transfer to the valence band of PCN, enhancing both the oxidation and reduction capabilities of the catalytic system. This process induces significant H2O2 generation via both reduction and oxidation reactions. The produced H2O2 further complexes with uranyl ions to form studtite precipitates, thereby achieving efficient uranium separation. The system achieves a U(VI) separation efficiency of 95.8% within 210 min of illumination. Unlike traditional photocatalytic reduction of U(VI), this reaction is unaffected by air atmosphere or carbonate, enabling 100% uranium extraction from 4 L of natural seawater under sunlight.

This review paper presents an in-depth synthesis of the environmental aspects associated with the mining of the Baiyinchang Cu–Zn–Pb deposit in China. The review covers contamination by atmospheric deposition and sewage irrigation, soil contamination, and ecosystem health to evaluate current environmental conditions, identify potential impacts, and suggest sustainable mitigation measures for the Baiyin district. With a focus on soil, river water, and crop pollution levels, our review indicates that several heavy metals (HMs), particularly Cd, have been gradually accumulated in soils and streams due to the natural occurrence of the deposits close to the surface and mining–smelting activities, and pose a serious environmental threat. Detailed studies on sulfide minerals have found that although Cd is mainly hosted in sphalerite, all common sulfide minerals (galena, chalcopyrite, pyrite) also contain Cd. There were significant spatial variations in HM speciation; upstream areas near ore deposits exhibited lower pH and higher Zn concentrations, due to acidic mine drainage and the presence of sphalerite. As the stream flows through the Baiyin district, the increasing influence from domestic wastewater led to a rise in pH, impacting HMs mobility. Mining–smelting activities were identified as the primary source of HM pollution. Crops grown near the ore district and irrigated with contaminated water were most susceptible to contamination due to combined soil and atmospheric HM uptake. Our review highlights the importance of stricter pollution control measures, cleaner irrigation sources, and careful crop selection to safeguard food safety and ecosystem health.

The differential uptake and metabolism pathways of polycyclic aromatic hydrocarbons (PAHs) in plants significantly affect their phytoremediation capabilities and environmental longevity. Here, we utilized confocal laser scanning microscopy combined with non-targeted metabolomics to clarify the specific absorption processes and physiological responses of Medicago sativa (alfalfa) to phenanthrene (PHE) and pyrene (PYR). Alfalfa roots demonstrated selective accumulation of both PAHs, exhibiting spatial heterogeneity: PHE was mostly concentrated in vascular cylinders, whilst PYR was found in epidermal and cortical tissues. This discrepancy indicates different transport mechanisms-PHE employs both symplastic and apoplastic pathways, while PYR depends only on apoplastic translocation. Metabolic profiling revealed PHE breakdown products that suggest a new phthalic acid route characterized by dehydrogenation and ring-opening events. Simultaneously, exposure to PAHs induced a 2-3 fold rise in ROS generation and caused significant photoinhibition of PSII, resulting in an 7.93 % reduction in Fv/Fm. Metabolomics disturbances indicated a systemic dysregulation of galactose metabolism (e.g., upregulated of raffinose) and flavonoid/isoflavonoid production (0.36 fold in 7, 4'-dihydroxyflavone), undermining antioxidant defenses. These findings demonstrate a mechanistic link between the compartmentalization of PAHs, their metabolism, and oxidative stress, providing critical insights for refining targeted phytoremediation strategies and improving ecological risk assessments for mixed PAHs contamination.