Search Results (5,252)

Heavy metal(loid) pollution in watersheds surrounding mining areas originates from multiple and complex sources, posing persistent threats to terrestrial–aquatic ecosystems and human dietary safety. This study systematically investigated the pollution characteristics, spatial distribution, ecological risks and human health hazards of seven typical heavy metal(loid)s (As, Pb, Cr, Cd, Cu, Zn, and Ni) in the integrated water–soil–vegetable continuum of a mining-affected watershed in Southwest China. Field sampling was carried out in three functional zones with different mining disturbance intensities, and inductively coupled plasma mass spectrometry (ICP-MS) was used to detect heavy metal(loid) concentrations in all samples. Multiple pollution evaluation indices and the USEPA human health risk assessment model were adopted for comprehensive quantitative analysis. The results showed that 44.0% of surface water samples exceeded national permissible limits, with high-pollution areas concentrated in intensive mining zones, presenting moderate overall aquatic heavy metal(loid) pollution. Although the average concentrations of seven heavy metal(loid)s in riparian soils complied with Chinese agricultural soil screening standards, localized significant enrichment was observed for As (1.98 times), Cd (4.62 times), Cu (1.81 times), and Zn (2.72 times) compared with regional background values, causing mild comprehensive soil pollution. Farmland soils exhibited prominent Cu and Zn accumulation, and leafy vegetables in the study area suffered severe Pb and Cd pollution, with potential dietary exposure risks. Health risk assessment indicated that children face higher non-carcinogenic and carcinogenic risks than adults via soil hand-to-mouth exposure; dietary intake of vegetables leads to moderate carcinogenic risks for children caused by As and Ni exposure. Overall, this study clarifies the migration and enrichment rules of heavy metal(loid)s in the water–soil–vegetable system of mining watersheds, confirms the prominent ecological and human health risks of Cd, As and Pb in the study area, and provides targeted basic data for regional heavy metal(loid) pollution prevention and food safety management. Full article

African soils face increasing levels of metal pollution due to industrialization, artisanal mining activities, improper waste management, and enhanced agricultural productivity. However, unlike many organic pollutants, heavy metals do not degrade naturally and therefore persist in environmental systems for prolonged periods. Heavy metals accumulate over many decades in the soil and bioaccumulate through the food chain causing severe health complications such as cancer, kidney problems, and neurological impairment. This paper reviews the current literature on the origin, prevalence, and behavior of the main pollutants Pb, Cd, Cr, As, Hg, and Cu. The major phytoremediation methods including phytoextraction, rhizofiltration, phytostabilization, and phytovolatilization are highlighted alongside in planta screening methods for hyperaccumulating plants including Berkheya coddii (Ni) and Haumaniastrum robertii (Co). The paper evaluates various enhancement techniques such as the use of chelators, Rhizobium inoculations, and genetic modifications. The significance of these approaches in tropical and subtropical climates is discussed. The paper suggests a holistic framework involving empirical kinetic modeling, geospatial machine learning (random forest, kriging), and molecular omics in prediction modeling. Major hurdles in such predictions include lack of field-based verification of the models, biotechnology safety of genetically modified (GM) organisms, and inadequate regulations. Future perspectives emphasize community-driven phytomining, biomass recycling, and resilient phytoremediation solutions. Full article

Introduction: Establishing baseline descriptions of inorganic elements in the early life stages of sharks and in their respective nursery areas is essential for assessing anthropogenic impacts and supporting conservation strategies. Objectives: This study presents the first baseline of plasma trace element concentrations (Al, Zn, As, Cu, Cr, Cd, Co, Mn, Ti, Ni, Hg, Pb) for four juvenile shark species (Carcharhinus limbatus, Paragaleus pectoralis, Rhizoprionodon acutus, and Sphyrna lewini) from Sal Rei Bay, Boa Vista Island, Cabo Verde—the first multi-species shark nursery area described in Atlantic Africa. Methodology: Seawater and sediment samples were collected from eight sites and analyzed along with plasma samples using total reflection X-ray fluorescence spectroscopy (TXRF). Sediment granulometry and pollution indices, including the enrichment factor (EF), ecological risk index (RI), and metal pollution index (MPI), were used to characterize habitat contamination. Data were analyzed using statistical models to explore spatial and element-specific patterns. Results: Overall, environmental contamination was low, with slight increases in Cd, Co, and Hg at sites 1 and 2, near the fishing port, and at site 5, likely reflecting natural transport, sediment redistribution, and enhanced nearshore deposition. Juvenile sharks exhibited generally low plasma trace element concentrations, although species-specific elemental signatures were evident: elevated levels of Al and Cu in C. limbatus, Zn in S. lewini, and As in R. acutus and P. pectoralis. Conclusions: These findings establish critical baseline reference values for trace elements in juvenile sharks from a key Atlantic nursery area. The results provide an essential framework for future biomonitoring efforts and contribute to the management and conservation of Cabo Verdean shark nursery habitats. Full article

High-entropy alloy (HEA) coatings exhibit enhanced chemical stability when doped with carbon, primarily due to the strong bonding between carbon and transition metals. Typical transition metals used in these coatings include Cr, Fe, Co, Ni, Cu, Ti, V, W, Nb, Ta, and Zr. Owing to their excellent chemical stability, HEA coatings are widely employed to protect component surfaces operating in highly corrosive environments. Against this backdrop, the present study investigates the effect of carbon doping introduced via methane gas flow during the physical vapor deposition of TiAlTaZrNb HEA coatings on corrosion resistance. The morphology and structure of the coatings were analyzed by field emission scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Corrosion protection and coating resistance were assessed through potentiodynamic polarization and electrochemical impedance spectroscopy. While increasing the methane flow resulted in an approximately 34% reduction in coating thickness, the overall coating resistance increased by one order of magnitude, reaching a maximum at a methane flow rate of 9 sccm, corresponding to the carbon solubility limit. This improvement was evidenced by a decrease in the corrosion rate from 8.02 × 10⁻² mm y⁻¹ for the uncoated H13 steel to 8.00 × 10⁻⁴ mm y⁻¹ for the HEA-coated samples. However, at higher methane flow rates, carbon precipitation and the formation of parallel microcracks contributed to an increase in corrosion rate. Full article

Background/Objectives: Red beetroot (Beta vulgaris L.) is recognized for its antioxidant, anti-inflammatory, and metabolic properties. This study evaluated the effects of two beetroot cultivars (Boldor and Wodan) on blood serum parameters, body composition, and organ weights in male WKY rats fed a low-protein diet (LPD, 8.8% protein). Methods: Five-week-old male rats were maintained on an LPD for 8 weeks and subsequently continued on the LPD diet supplemented with 4% dried beetroot for 45 days. The experimental diets included beetroot from the Boldor and Wodan cultivars, either treated or untreated with a plant growth stimulator during cultivation. Results: Foliar application of the selenium-based plant growth stimulator did not significantly increase selenium or other element concentrations in beet roots. Elemental analysis showed higher levels of Fe, Zn, Cu, Cr, Pb, As, Cd, and Sb in the Wodan group, while Boldor increased Cr, Pb, and As; Ni and Se remained unchanged. Beetroot supplementation significantly affected 14 of the 30 measured biochemical parameters, including biomarkers of liver function (ALT, ALP, total bilirubin, albumin, and total protein), renal function (uric acid), pancreatic activity (amylase and lipase), electrolyte balance (sodium, potassium, and chloride), mineral metabolism (calcium), inflammatory status (CRP), and nutritional metabolism (iron). Conversely, no significant effects were observed on lipid profile parameters or biomarkers of cardiac and skeletal muscle injury. Among the beetroot cultivars evaluated, Wodan exerted distinct effects relative to Boldor, resulting in higher circulating total bilirubin and potassium concentrations, alongside reduced uric acid and lipase levels in treated rats. Boldor supplementation significantly increased body weight gain and fat mass, with a trend toward higher lean mass, and increased kidney weight. Wodan did not significantly affect body weight but increased kidney and spleen mass. Feed intake was similar across groups. No changes in cardiovascular function were observed ex vivo. Conclusions: Beetroot supplementation modulated multiple metabolic and physiological biomarkers in rats fed a low-protein diet, with distinct cultivar-specific effects, underscoring the importance of cultivar selection for optimizing functional dietary interventions. Full article

The Chishui River Basin, a core production area for Chinese sauce-aroma Baijiu (exemplified by Moutai), supports sorghum cultivation critical to the liquor’s distinctive quality. The soil environment quality within this region, therefore, directly impacts the safety and quality of both raw material and the final distilled spirit. To underpin the safe production and sustainable development of this iconic beverage, it is essential to assess soil heavy metal contamination in the soils and quantify the contributions from various sources. In this study, 172 surface soil samples were collected from typical sorghum planting bases in the Renhuai area. Concentrations of eight heavy metals (loids) (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) were determined. The contamination status was evaluated using the geostatistical inverse distance weighting interpolation, the Nemerow pollution index (P_N), and the potential ecological risk index (RI). Source identification and quantification were performed using the positive matrix factorization receptor model (PMF). Results revealed significant enrichment of Cd and Hg in the soil, with mean concentrations 2.07 times and 2.54 times the soil background values for Guizhou Province, respectively. Pollution index results (P_i, P_N) indicated that soil Cd contamination is relatively severe, whereas contamination from other elements is minimal. Overall, approximately 86.5% of the study area was classified as clean or only slightly polluted. Cd poses a moderate ecological risk and was the primary contributor to the total ecological hazard. Other elements exhibited lower risk, resulting in a slight overall potential ecological risk. The soil environmental quality in certified organic sorghum bases was generally favorable. PMF analysis identified three principal sources: historic industrial emissions and traffic-related sources (contributing 46%), weathering of carbonate rocks combined with agricultural activities (37%), and natural background coupled with organic fertilizer application (17%). In conclusion, while the overall soil heavy metal pollution level in the sorghum planting areas is low, the notable enrichment and higher ecological risk of Cd necessitate enhanced dynamic monitoring and targeted risk control measures to ensure long-term soil health and product safety. Full article

Sandstone-type uranium deposits are the main source of uranium in China. The Ordos Basin, one of the most typical Mesozoic intracontinental sedimentary basins in northern China, is a major uranium-bearing basin in China. The Hangjinqi area is a significant uranium-bearing region in the northern Ordos Basin, with favorable geological conditions and promising exploration prospects for mineralization, and the Lower Cretaceous Huanhe Formation is one of the uranium-bearing strata in this area. This study focuses on the Huanhe Formation in the Hangjinqi area to investigate the governing factors of uranium enrichment and mineralization in this stratum. U-Pb dating of detrital zircons from sandstones of the Huanhe Formation reveals dominant peak ages of 2370–2585 Ma, 214–320 Ma, and 1805–2325 Ma, and secondary peak ages of 340–506 Ma, 1598–1797 Ma, and 110–150 Ma. The age results of the selected detrital zircons indicate that the provenance of the Huanhe Formation is mainly derived from three sources: (1) the 2.6–2.5 Ga TTG gneisses and granulites in the Yinshan Block; (2) the Paleoproterozoic (2500–1800 Ma) khondalites and granitic gneisses in the Daqingshan–Wulashan–Jining area, as well as granites in the Yinshan area; and (3) large-scale intermediate–acidic intrusive rocks and volcanic rocks of the Yinshan orogenic belt, whose ages range from 110.9 to 505.9 Ma (predominantly Paleozoic). These source rocks may have provided a potential uranium source. The paleoclimate proxies, including Sr/Cu, Sr/Ba, V/Cr, Ni/Co, and Fe²⁺/Fe³⁺ ratios, combined with the Chemical Index of Alteration (CIA) and the Index of Compositional Variability (ICV), suggest that the Huanhe Formation was formed in a relatively arid and oxidized environment with a low degree of chemical weathering, which facilitated the migration of uranium-bearing ore-forming fluids. The sedimentary environment, provenance, and paleoclimate created favorable geological conditions for uranium enrichment in the Huanhe Formation of the northern Ordos Basin. Full article

The sluggish kinetics of alkaline hydrogen oxidation reaction (HOR) and high cost of Pt–based catalysts have long hindered large–scale deployment of alkaline membrane fuel cells. Via first–principles calculations, we designed a series of 3d transition metal single atoms anchored on PdN₂ monolayer (TM–PdN₂, TM = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) and evaluated their alkaline HOR performance. Ti-, Cr-, Fe-, Co-, Ni-modified systems exhibit excellent thermodynamic and electrochemical stability under operating conditions. Single-atom doping tunes the p-band center of N and d-band center of metal sites, enabling precise modulation of H and OH adsorption strengths. Mechanistic analysis reveals HOR follows H₂ + 2OH* → H* + OH* + H₂O → 2H₂O, with the final step as rate-determining step. H adsorption contributes 3.45 times more to HOR activity than OH adsorption. Fe–PdN₂ delivers the best performance, with an ultra–low barrier of 0.11 eV and a rate constant of 2.82 × 10¹⁰ s^–1·site⁻¹, values that significantly outperform those of Pt(111) (0.22 eV, 4.5 × 10⁹ s⁻¹·site⁻¹). This work provides theoretical guidance for rational design of high–performance alkaline HOR electrocatalysts. Full article

Source apportionment and the elucidation of driving mechanisms are essential for targeted soil pollution management. This study investigated surface soils across six towns in southern Shimen County, northwestern Hunan Province, where 662 samples were collected to determine the concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn. Multivariate statistics and the APCS-MLR receptor model were integrated to quantify pollution sources, while three machine learning models (RF, XGBoost, and LightGBM) were applied to identify key drivers of the spatial enrichment of Cd. Results showed that Cd was significantly enriched, with a mean concentration of 0.43 mg/kg (3.41 times the provincial background value). The mean concentrations of As, Cr, Cu, Ni, Pb and Zn were 11.97 mg/kg, 81.01 mg/kg, 24.15 mg/kg, 49.25 mg/kg, 29.56 mg/kg and 76.77 mg/kg, respectively, and these PTEs remained at normal background levels. Significant inter-element correlations indicated common sources. Three primary sources were quantified—natural parent material (43.83%), mining activities (30.99%), and mixed sources of coal mining and agricultural inputs (7.84%), with 17.34% attributed to unidentified mixed sources. Natural sources dominated the geogenic enrichment of Cd, Cu, Ni, Pb, and Zn; mining activities governed the accumulation of As, Cr, Cu, and Pb; a mixed source of coal mining and agricultural practices contributed substantially to Cd enrichment. Machine learning identified PM10, topography, strata, and soil type as dominant drivers, with their total feature importance reaching 70.05%. Among these factors, natural factors and anthropogenic factors accounted for 44.23% and 55.77% of the total feature importance, in turn revealing coupled natural–anthropogenic controls. This study establishes an integrated framework linking source apportionment and driver identification, providing scientific insights for potentially toxic elements (PTEs) control in analogous mining–agricultural regions. Full article

Copper (Cu) thin films and meshes on polyethylene terephthalate (PET) substrates are promising flexible transparent conductive electrodes (TCEs), yet their practical use is limited by insufficient interfacial adhesion and poor oxidative stability on inert polymer substrates. This work addresses these issues via a synergistic strategy of interfacial layer engineering and maskless laser lithography-based aperiodic mesh patterning, systematically comparing ceramic (Al₂O₃) and metallic (NiCr) interfacial layers for PET-supported Cu films and fabricating Linear/Sinusoidal aperiodic Cu meshes with tailored performance. Magnetron sputtering shows that Ar plasma-activated NiCr interfacial layers form a gradient-alloyed interface with Cu via interdiffusion, achieving 5B-level adhesion, mitigating bending-induced stress concentration, and enhancing damp-heat resistance (85 °C/85% RH) by suppressing oxidation—outperforming brittle Al₂O₃ layers. Patterning the optimized Cu/NiCr/PET structure into micrometer-scale meshes yields a Linear design with superior optoelectronic performance (~10.8 Ω/sq sheet resistance, >87% transmittance at 550 nm) and a Sinusoidal design with enhanced bending robustness via stress delocalization. Microstructural and elemental analyses clarify the NiCr layer’s interfacial toughening and anti-oxidation mechanisms. Practical validation in flexible transparent heaters demonstrates rapid thermal response and >20 h continuous operational stability. This study provides a scalable design strategy for high-performance PET-supported Cu meshes, offering insights for interface and structural optimization of flexible metallic TCEs for next-generation optoelectronics. Full article

Plant growth-promoting rhizobacteria (PGPR) foster sustainable and environmentally friendly agriculture by promoting plant growth and development. PGPR colonize the root rhizosphere, rhizoplane and root tissues, where they drive organic matter turnover and nutrient cycling, thereby increasing the (phyto)availability of essential macro- (P, N, K, S, Ca, Mg) and micronutrients (Fe, Zn, Mn, Mo, Co, Ni, Cu, B). This process relies on various mechanisms, including acid secretion (rhizospheric acidification and metal chelation), siderophore production (binding Fe, Zn, and other metals) and hydrolytic enzyme-mediated catalysis (phosphatases, phytases). Some of these microorganisms can also modulate the phytohormonal balance, reshaping root architecture and enhancing nutrient uptake, and even can alleviate abiotic stress or serve as biocontrol agents, contributing to pathogen resistance. Even though plant cultivation practices relying solely on synthetic fertilizers rapidly increase crop yield and productivity, they eventually result in crops poor in essential micronutrients and trace elements. This may contribute to micronutrient malnutrition in the human population. On the contrary, PGPR enhance both crop yield and nutritional quality. Therefore, in utilization with other nutrient sources, PGPR provide a promising and scalable approach towards advancing environmentally sustainable agriculture systems. Full article

The efficient conversion of methane into hydrogen-rich syngas is essential for sustainable energy; however, integrating methane partial oxidation (POM) with the water–gas shift (WGS) reaction remains a significant challenge due to thermal and kinetic mismatches. This research presents a spatially decoupled dual-bed reactor configuration, utilizing Ni/GDC and Cu/GDC catalysts, to achieve synergistic hydrogen production. Unlike conventional physically mixed systems, which suffer from thermal hotspots and the unintended promotion of the endothermic Reverse Water–Gas Shift (RWGS) reaction, the dual-bed architecture effectively segregates the reaction zones. Advanced characterization, including O₂-TPO and Raman spectroscopy, reveals that the GDC support acts as a critical oxygen buffer via the Mars-van Krevelen mechanism, modulating the dynamic redox state of the active metal sites to prevent deep oxidation and carbonaceous deactivation. Furthermore, macroscopic performance and carbon–oxygen mass balance analyses confirm that this rational architectural design facilitates a seamless integration of POM and WGS pathways, resulting in significantly maximized H₂ yield. From a broader engineering perspective, this dual-bed strategy offers a practical, low-complexity alternative to intensive integrated technologies such as sorption-enhanced reforming (SER) or chemical looping, providing a robust and scalable framework for durable, high-efficiency hydrogen production. Full article

Soil contamination by heavy metals (HMs) [or potential toxic elements (PTEs)] poses serious risks to ecosystems and human health. Metals persist in the environment and can reach groundwater and freshwater as part of the food-chain. In soils, anthropogenic inputs dominate over geogenic sources. Metal mobility is strongly controlled by factors such as pH, mineralogy, and erosion processes that transport metal-bearing clay fractions. Wind and water can transport soil, mainly clay particles that can usually bind contaminants such as HMs. Using waste material is a tool suggested from the circular economy, so waste becomes a valuable resource. This study evaluates the immobilization efficiency of several heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) using phosphate amendments—synthetic hydroxyapatite, phosphatic rock from Florida and Morocco—applied to a brownfield site. Heavy metal immobilization followed a two-step mechanism: first rapid surface complexation and secondly partial dissolution of hydroxyapatite and ion exchange with Ca, leading to the precipitation of metal-substituted hydroxyapatite phases. Synthetic hydroxyapatite generally shows the best efficiency, whereas phosphatic rocks were less effective but still provided a measurable immobilization. From a circular economy perspective, however, phosphatic rocks remain attractive due to their lower cost, availability, and waste-valorization potential. Full article

Geochemical data provide direct constraints on mineralization, and the extraction of mineralization-related geochemical anomalies is essential for mineral resource prediction and assessment. The regional geochemical field reflects the spatial expression of ore-forming environments resulting from the superposition of multiple geological processes, with distinct elemental assemblages corresponding to different processes. The Ailaoshan metallogenic belt, located in the southeastern segment of the India–Eurasia collisional orogen, experienced multiple episodes of opening and closure, extension, amalgamation, and compression, leading to intense deformation. Its complex structural framework, multistage magmatism, and metamorphism have generated abundant mineral resources, particularly Au, Sn, Cu, Pb-Zn, and Ni deposits. Using the 1:200,000–scale national stream sediment geochemical dataset, principal component analysis (PCA) was applied to identify major ore-forming elemental assemblages. Singular value decomposition (SVD) was then used to extract regional and local anomalies for PC2 (Ag-As-Bi-Cu-Mn-Pb-Sn), PC3 (B-Be-Bi-Cu-F-W), PC4 (La-Nb-Th-U-Y-Zr), and PC10 (Au-Hg). Ultimately, six metallogenic prospective areas were consequently delineated. Full article

Next-generation wastewater treatment and recycling rely on membrane-based processes, but they face a trade-off among permeability, selectivity, and fouling resistance. In the present study, thin-film nanocomposite (TFN) membranes were fabricated by incorporating a ternary TiO₂-SiO₂-biochar nanofiller into a polysulfone (PSf) support using nonsolvent-induced phase separation, after which m-phenylenediamine and trimesoyl chloride were used via interfacial polymerization to produce a selective polyamide layer. The membrane compositions were M1 (22 wt.% PSf), M2 (22 wt.% PSf/0.5 wt.% TiO₂/0.5 wt.% SiO₂/0.5 wt.% biochar), and M3 (polyamide-coated M2). FTIR, XRD, SEM, contact-angle, porosity, and mechanical analyses supported successful membrane formation and changes in morphology, wettability, and structural strength after nanofiller incorporation and TFC coating. The addition of a nanofiller increased the hydrophilicity of the membranes by decreasing the water contact angle from 98.6 ± 0.8° for pristine PSf to 35.6 ± 1.5° for the nanocomposite membrane. Consequently, the pure-water permeability increased from 21 to 37 L m⁻² h⁻¹ bar⁻¹. After polyamide layer formation, the optimized TFN membrane maintained a contact angle of 55.4 ± 3.8° and achieved a high Congo red rejection of 98% with permeate flux of 7–9 L m⁻² h⁻¹ bar⁻¹. The membrane also showed good antifouling performance, with flux recovery ratios exceeding 90%. For heavy-metal-containing solutions, the optimized membrane showed apparent removal efficiencies of 78–98% for multivalent heavy metals (Pb²⁺, Hg²⁺, Cd²⁺, Mn²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Fe³⁺, As³⁺, and Cr⁶⁺). Static adsorption tests showed the order M2 > M3 > M1, confirming that exposed TiO₂-SiO₂-biochar sites contribute to pollutant uptake, while the superior filtration performance of M3 is attributed to the combined effect of the polyamide selective layer and adsorption-assisted interactions. Overall, the TiO₂-SiO₂-biochar-based TFN membrane provides a promising platform for dye removal and preliminary heavy-metal attenuation from contaminated water. Full article