Search Results (429)

Thiol-modified attapulgite (TM) combined with manganese sulfate (MnSO₄) can reduce cadmium (Cd) availability in alkaline soils, but the influence of MnSO₄ application timing on Cd transfer to wheat grain remains unclear. In this study, a soil incubation experiment and two wheat pot experiments were conducted to evaluate soil Cd immobilization, organ-specific Cd distribution, and the effects of applying MnSO₄ before sowing, at the jointing stage, or at the grain-filling stage. Low- and high-dose MnSO₄ treatments were applied alone or with TM, and the combined treatments were defined as TM+LS and TM+HS. Compared with the untreated control, TM+LS and TM+HS decreased dissolved Cd from 1.80 μg L⁻¹ to 0.35 and 0.20 μg L⁻¹, respectively, and reduced grain Cd from 0.19 mg kg⁻¹ to 0.08 and 0.06 mg kg⁻¹. These reductions were associated with decreased DTPA-extractable Cd, enhanced Cd adsorption, lower Cd desorption, and restricted Cd transfer from roots to shoots and from glumes to grains. Jointing-stage MnSO₄ application produced the lowest grain Cd concentration and glume-to-grain transport coefficient. These findings indicate that optimizing MnSO₄ application timing can improve TM-assisted Cd immobilization and wheat grain safety in alkaline Cd-contaminated soil. Full article

Fibrillated egg white protein (FEWP) has promising emulsifying functionality, whereas excessive association may restrict the organization of freshly prepared emulsions. This study examined the concentration-dependent effects of γ-cyclodextrin (γ-CD; 0.5%, 1%, and 2%, w/v) on 3% (w/v) FEWP dispersions and the resulting oil-in-water emulsions. Relative to native egg white protein (NEWP), redispersed FEWP showed a smaller apparent hydrodynamic diameter (36.56 vs. 371.97 nm). γ-CD caused only minor changes in particle size and a non-monotonic intrinsic-fluorescence response. Among the γ-CD levels tested, 1% produced the highest intrinsic fluorescence intensity, emulsifying activity index (2.56 m²/g), and emulsion stability index (207.87 min). In the observed microscopic fields, this formulation contained fewer conspicuous large droplets and a visually more uniform spatial distribution than the other FEWP-γ-CD formulations. It also moderated progressive microscopic immobilization and maintained elastic-dominated, shear-thinning, and partially recoverable behavior. Increasing γ-CD to 2% reduced emulsifying performance and bulk structural connectivity. Thus, 1% γ-CD provided the most favorable combination of short-term emulsifying and rheological properties among the concentrations examined. Full article

Biochar has been widely applied for immobilization of potentially toxic elements (PTEs) in contaminated soils; however, its effects on metal transport under transient unsaturated conditions remain insufficiently understood. This study investigated the adsorption, desorption, and transport behavior of Pb²⁺ and Cd²⁺ in biochar-amended soils by combining batch experiments, unsaturated conditions column experiments, and transport modeling. The adsorption kinetics, isotherms, and desorption characteristics of Pb²⁺ and Cd²⁺ were evaluated under different biochar levels, and their redistribution during unsaturated infiltration was further analyzed using soil–water-dependent models. Biochar increased the apparent adsorption capacity of both metals, with a stronger response observed for Pb²⁺ than Cd²⁺. The Elovich and two-constant models provided better statistical descriptions of adsorption kinetics than the pseudo-second-order model, indicating that adsorption rate behavior involved heterogeneous and multi-rate processes. Freundlich fitting showed that Pb²⁺ and Cd²⁺ exhibited non-ideal adsorption behavior, while desorption experiments demonstrated a stronger reduction in apparent Pb²⁺ release compared with Cd²⁺ under biochar. Under transient unsaturated infiltration, Pb²⁺ and Cd²⁺ exhibited distinct transport patterns. Pb²⁺ redistribution was adequately described by a linear partitioning relationship, with R² values ranging from 0.988 to 0.990, indicating relatively stable solid–liquid partitioning within the tested conditions. In contrast, Cd²⁺ showed stronger dependence on soil–water conditions, and an empirical nonlinear water-dependent model improved model performance, increasing R² values from 0.533–0.652 for the linear model to 0.903–0.973. The results suggest that biochar effects on potentially toxic element migration under unsaturated conditions are element-specific, involving both apparent sorption enhancement and water-dependent redistribution processes. This study highlights that biochar performance in potentially toxic elements remediation should not be evaluated solely based on equilibrium adsorption capacity. Under field-relevant unsaturated conditions, amendment effectiveness may also depend on interactions between metal-specific retention behavior and soil hydraulic variability. Further studies integrating structural characterization, long-term aging, and reactive transport modeling are required to validate these processes under heterogeneous field conditions. Full article

Bacterial contamination remains a critical safety concern in platelet transfusion, and there is an urgent demand for decontamination technologies that eliminate contaminating bacteria without damaging platelet viability and physiological function. Herein, Fe₃O₄-QCS-PEI-Cu-apt microparticles with enlarged magnetic cores were rationally fabricated to improve aptamer immobilization, aiming at targeted bacterial elimination via near-infrared (NIR) irradiation while maintaining platelet function. Fluorescence assays confirmed their specific targeting capability toward Staphylococcus aureus (S. aureus) without binding to platelets. Magnetic separation experiments demonstrated that the aptamer-functionalized microparticles could efficiently capture and remove 91.35% of S. aureus from platelets. NIR irradiation of the Fe₃O₄-QCS-PEI-Cu core induced marked bactericidal activity against S. aureus in suspension, as determined by plate counting and LIVE/DEAD staining. This antibacterial ability originated from the intrinsic photo-responsive property of the composite rather than from aptamer-mediated recognition, and could be easily extended to bacteria captured by aptamer-functionalized particles. Comprehensive biocompatibility evaluations, including morphological observation, hematological parameter analysis, CD62P expression detection, and thromboelastography (TEG) were performed. And the results demonstrated that there were no significant changes in platelet morphology, count, activation state, or overall hemostatic function, apart from an increase in the α angle. This platform achieves efficient targeted NIR-triggered antibacterial efficacy while maintaining excellent platelet compatibility, offering a promising strategy to enhance the safety of platelet transfusion. Full article

Iron (Fe) deficiency and cadmium (Cd) contamination often co-occur in agricultural systems, yet the way in which Fe deficiency modulates Cd translocation remains unclear. Here, we investigated root cell wall modifications mediating Cd accumulation in two peanut cultivars with contrasting Fe deficiency tolerance. Fe deficiency significantly increased root Cd concentrations in both cultivars but reduced Cd translocation to shoots, an effect more pronounced in the tolerant cultivar Silihong. Cell wall analysis revealed cultivar-specific compositional changes: pectin and cellulose increased under combined Cd exposure and Fe deficiency, while hemicellulose (HC1) decreased. Negative correlations between Fe and Cd accumulation in roots, cell walls, and their components indicate competition between these two metal ions for binding sites in root cell walls. Increased pectin content under combined stress enhances Cd sequestration, while reduced HC1 content facilitates Fe mobilization to shoots. Transcriptomic analysis identified hub genes associated with cell wall modification, including pectinesterases (PME2/4/29/63), beta-galactosidases (BGAL3/5/8), polygalacturonases (PGs), pectin acetylesterases (PAE8), xyloglucan endotransglucosylase/hydrolases (XTH8/31) and laccases (LAC7/11/15). Under combined stress, Silihong exhibited superior Cd immobilization, characterized by higher Cd accumulation in HC1 and cellulose fractions, stronger induction of PME, PAE8 and LAC genes, and greater suppression of XTHs, PGs, and BGALs. Our findings demonstrate that Fe deficiency restricts Cd translocation by remodeling root cell walls, increasing pectin and cellulose while modulating hemicellulose integrity, thereby creating an expanded apoplastic reservoir that traps Cd. This structural detoxification mechanism, operating downstream of uptake transporters, identifies key cell wall components and regulatory genes as potential targets for breeding peanut cultivars with improved food safety. Full article

Microbiologically induced calcium carbonate precipitation (MICP) links microbial metabolism with carbonate biomineralization and offers a platform for environmental protection and a circular bioeconomy. This critical review synthesizes ureolytic and non-ureolytic pathways, including denitrification, sulfate reduction, photosynthesis, ammonification and carbonic-anhydrase-mediated routes, and evaluates their efficiency, scalability, environmental impacts and field applicability. MICP can immobilize heavy metals and metalloids, stabilize soils and mine wastes, reduce permeability, control erosion and dust, seal cracks in cementitious materials, and support brine or wastewater treatment. Representative studies report >90% Cd²⁺ removal in selected wastewater systems, 50–90% hydraulic-conductivity reduction at about 10–15% CaCO₃, 2.7 MPa compressive strength in urine-based bio-bricks, 31.87% calcium-source cost reduction using waste-limestone-derived calcium acetate, and geothermal-brine treatment removing 96% Ca, 88% Mn, and 91% Sr while retaining >96% Li. The review emphasizes that circular MICP requires more than waste input substitution; it must include nitrogen management, feedstock quality control, long-term contaminant stability, LCA/TEA, regulatory readiness, biosafety, field monitoring, and technology-readiness assessment. Future research should develop low-ammonia, waste-fed and data-guided MICP systems with standardized quantitative performance metrics. Full article

The fate of heavy metals in agricultural soils is governed by organo-mineral–microbial interactions, which predictive models often fail to capture. The competitive sorption mechanisms of Cd(II) and Cu(II) on montmorillonite/kaolinite composites (Mont/Kao) functionalized with humic acid (HA) and Pseudomonas putida (P. p), a model system representative of contaminated agricultural soils, were investigated. Batch experiments, XRD, FTIR, and thermodynamic analysis reveal that metal retention is a non-additive function of competing interfacial processes. Bacterial biomass dominated sorption, accounting for >50% of total metal uptake, with capacity ranked as: P. p > Mont/Kao-P. p > Mont/Kao-HA-P. p > Mont/Kao-HA > Mont/Kao. Humic acid exerts a dual, concentration-dependent role: Low levels enhanced adsorption via mineral dispersion, while high levels induced surface masking, suppressing bacterial binding sites. Competition was highly asymmetric: Cd(II) reduced Cu(II) maximum adsorption capacity by 75.5% in the Mont/Kao-HA system by preferentially occupying montmorillonite interlayer sites, whereas Cu(II) inhibited Cd(II) below pH 6. Single-metal sorption was characterized by positive ΔS° (32.96–58.89 J·mol⁻¹·K⁻¹), indicative of inner-sphere complexation, while negative ΔS° under competitive conditions signals a transition to outer-sphere complexation. This work provides mechanistic insights into site masking, competitive displacement, and ternary cation bridging controlling metal immobilization in organo-mineral assemblages. Full article

Lyophilized pectinase from Aspergillus niger (PeL) was immobilized onto polyamide 6 (PA6) microparticles (MPs) through an adsorption-based procedure within the pH range of 5–8, yielding four PeL@PA6 complexes. In contrast to commercial enological preparations that are complex enzymatic cocktails with unspecified exact compositions, the use of PeL with known specific activity enabled a more reliable evaluation and improvement of the immobilization process and of the structure–activity relationships of the resulting biocatalysts. Thermogravimetric analysis demonstrated better thermal stability of the PeL@PA6 complexes compared to neat PA6 MPs. UV-CD studies revealed that the secondary structure and conformational stability of PeL before and after immobilization were strongly pH-dependent, with maximum stability observed at pH 6–7. All four PeL@PA6 complexes retained significant catalytic activity and showed good tolerance to ethanol-rich media relevant to enological applications. Kinetic analysis indicated increased apparent K_m values after immobilization, suggesting diffusional limitations associated with the porous PA6 support. Clarification experiments of industrial white and rosé wine musts confirmed the practical applicability of the immobilized system. All PeL@PA6 complexes preserved the color and phenolic integrity of the musts, displayed good operational stability during reuse, and exhibited higher long-term storage stability than the free enzyme. These results demonstrate that PA6 MPs are promising supports for pectinase immobilization in wine clarification and related biotechnological applications. Full article

Heavy metal deposition along high-traffic roadsides poses a persistent threat to agricultural safety, yet the partition barrier efficiency across rhizosphere–root–shoot interfaces in perennial nut crops remains poorly understood, representing a significant research gap. This study determined the concentrations of potentially toxic elements in the rhizosphere soils and distinct organs (leaves, pericarp, and edible seeds) of Siirt pistachio trees along a distance gradient (0, 50, and 100 m, plus a control site) in the Siirt and Tillo districts. To filter analytical baseline noise, all raw datasets were subjected to strict solid-matrix limit of detection (LOD) screening using a standardized dilution factor of 30 mL/g (DF = 15 mL final volume/0.5 g sample mass). Soil analysis revealed that the alkaline pH (6.90–7.27) and highly calcareous nature (21.97–65.75%) of the rhizosphere acted as a powerful edaphic barrier, immobilizing metals in the soil and limiting their translocation to aboveground tissues. Plant accumulation followed a leaf > pericarp > seed hierarchy, proving the canopy’s role as an effective vegetative filter. Crucially for food safety, highly toxic Cd (<1.74 µg/kg) and Bi remained entirely below detection limits in edible seeds. Cr peaked in leaves (730.42–795.00 µg/kg) but was highly restricted in seeds. Detected kernel concentrations of As, Co, Ni, Pb, and Sb were strictly below international toxic thresholds, while essential Cu physiologically concentrated in seeds and leaves. Consequently, the cumulative Hazard Index (HI) remained exceptionally below the 1.0 critical safety limit for both adults (<0.18) and children (<0.32). This confirms that roadside pistachios pose zero non-carcinogenic health hazards and are completely safe for human consumption. Full article

This study investigates the spatiotemporal distribution of heavy metals in urban soils of Thessaloniki, Greece, over a four-year monitoring period (2021–2024). A total of 664 soil samples were collected across diverse land-use types during both wet (winter) and dry (summer) seasons. Soil physicochemical properties were analyzed alongside cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) concentrations. The results reveal distinct, element-specific accumulation dynamics driven by continuous anthropogenic inputs. Statistical and geospatial analyses confirm that Cd exhibits a highly significant, progressive accumulation and spatial expansion toward residential areas. In contrast, Cu and Pb demonstrate a gradual, chronic enrichment, eventually reaching a saturation point where winter precipitation is insufficient to offset summer deposition. Zn presents as a severe but temporally stable contamination burden, anchored to the northwestern industrial–port sector. Furthermore, the alkaline properties of the local urban soils were found to act as an effective sink, immobilizing contaminants and preventing downward leaching. The Geo-accumulation Index (I_geo) confirms a progressive decline in soil quality driven primarily by cadmium, while the other trace elements exhibit persistent, stable profiles. Overall, this study establishes a vital geochemical baseline of total heavy metal loading in Mediterranean urban soils, emphasizing the need for targeted emission controls and future mobile-fraction assessments to guide sustainable urban management. Full article

Heavy metal pollution has become a global environmental problem. Achieving efficient, stable, and sustainable immobilization of heavy metals by phosphorus (P)-modified biochar remains challenging because of the potential risk of P release. In this study, chitosan-embedded P-modified biochar (CPBC) was produced for the remediation of Pb(II), Cd(II), and Cr(VI). The specific surface area of CPBC was 5.5 times higher than that of the pristine biochar (BC), and the surface was enriched with functional groups such as -OH and -NH₃. P-modification facilitated the precipitation of the heavy metals, and chitosan blocked the precipitates inside the biochar. The nature of BC safeguarded the ability to transfer electrons and reduce Cr(VI) to Cr(III), which was further enhanced by the chitosan. Hence, the maximum sorption capacities of CPBC for Pb(II), Cd(II), and Cr(VI) were 29.23%, 129.13%, and 122.12% greater than those of BC. The sequential extraction confirmed that the immobilized Pb(II), Cd(II), and Cr(VI) on CPBC were highly stable, with the sum of acid-soluble and nonbioavailable fractions accounting for 89.14%, 83.73%, and 93.53%, respectively. In addition, chitosan effectively suppressed P release from the P-modified biochar, thereby improving its environmental safety while maintaining excellent heavy metal immobilization performance. The present study demonstrates that CPBC is an effective, environmentally friendly, and universal sorbent to remediate heavy metal pollution in water. Full article

Biogas slurry can enhance soil fertility, but the heavy metals it contains may pose potential ecological risks to soil-crop systems. To mitigate heavy metal pollution resulting from the application of biogas slurry to soil, this study investigated potential remediation strategies through the use of blended biochar application. In this study, soil incubation experiments were conducted to evaluate the immobilization performance of cow dung biochar (CB), corn straw biochar (SB), and blended biochar (cow dung + corn straw) (C3S7, C5S5, and C7S3) toward Pb, Zn, Ni, Cr, Cu, As, and Cd under different biogas slurry ratios (Z0, Z1:8, and Z1:4). The results concluded that immobilization efficiency consistently followed the order C7S3 ≥ C5S5 > C3S7 > CB ≈ SB, indicating that the blended biochar generally outperformed the two single biochar in the biogas slurry-irrigated soil system. Batch adsorption experiments showed that adsorption of all metals was better described by the pseudo-second-order model (R² > 0.94). Isotherm fitting further indicated that Zn, Ni, Cr, Cu, and Cd were better fitted by the Langmuir model, whereas Pb and As were better fitted by the Freundlich model. Physicochemical characterization, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS), and Fourier transform infrared spectroscopy (FTIR) analyses collectively suggested that the superior performance of blended biochar was associated with the integration of mineral-related characteristics from CB and surface chemical properties from SB, which together enhanced the synergistic fixation of coexisting metals. Consistently, biochar application reduced the potential ecological risk index (RI) of bioavailable heavy metals in soil, with blended biochar showing lower RI values than CB and SB. C7S3 exhibited the best performance in all treatments, highlighting the potential of blended biochar as an effective amendment for mitigating multi-metal pollution risks with biogas slurry utilization. Full article

Shanxi Province in China is one of the world’s major bauxite producers. The co-existence of coal and bauxite mining makes this province particularly prone to acid mine drainage (AMD) and, thus, a significant area for investigating heavy metal mobility in an aluminum-rich geological environment. In this study, heavy metal leaching from bauxite under simulated AMD conditions and the geochemical mechanisms controlling their mobility were examined in this study. XRF analysis demonstrated that the bauxite is predominantly composed of Al₂O₃, Fe₂O₃ and SiO₂, while XRD, FTIR, and SEM-EDS revealed that diaspore and kaolinite dominate bauxite, together with accessory Fe- and Ti-bearing phases, providing reactive surfaces for adsorption and precipitation. After batch leaching with synthetic acidic sulphate solutions (pH = 3), Ca(OH)₂ neutralization was regulated. The data reveal that pH is the key factor controlling heavy metal mobility. Acidic conditions enhanced metal release while alkaline conditions favored hydroxide precipitation, surface complexation and co-precipitation. The removal efficiency was 91%–99% for Cd and Zn, 100% for Cd and Zn, 69%–90% for Cr, 35%–100% for Cu, 92%–100% for Ni and up to 100% for Pb. The chemical and mineralogical composition played an indirect role by providing adsorption sites but did not prevent the release of metals under acidic conditions. These results reveal that pH adjustment is the major mechanism controlling heavy metal immobilization in AMD-impacted bauxite systems and contributes to the knowledge of geochemical processes controlling metal mobility in acidic mine drainage. Full article

This study investigated the efficacy and mechanisms of foliar-applied selenium nanoparticles (SeNPs) in reducing cadmium (Cd) concentrations and alleviating Cd toxicity in winter wheat grown in Cd-contaminated soil. Pot experiments were conducted to evaluate SeNPs of different particle sizes (50, 100, 200 nm) and concentrations (0.125, 0.25 mmol/L). Foliar SeNPs application achieved the dual objectives of significantly decreasing Cd while increasing selenium (Se) concentrations in wheat grain. High-concentration (0.25 mmol/L) SeNPs treatments were most effective, particularly with a particle size of 100 nm size. Compared with the control, SeNPs significantly reduced grain Cd concentrations by 18.9–70.5% and increased grain Se concentrations by 1.2–27.2 times. Durum wheat exhibited a stronger response than soft wheat. The primary mechanisms included: (1) enhancing antioxidant defense: SeNPs significantly boosted superoxide dismutase (55.2–165.2%) and peroxidase (36.5–182.6%) activities, effectively scavenging reactive oxygen species, reducing oxidative stress markers malondialdehyde (12.0–35.1%) and regulating hydrogen peroxide (7.9–64.1%), which mitigated membrane lipid peroxidation. (2) Regulating subcellular Cd distribution: SeNPs increased the proportion of Cd immobilized in the cell wall by 2.9–39.6% and decreased Cd in organelles by 9.1–38.4%, thereby reducing its bioavailability and toxicity. This study provides a theoretical basis for using foliar SeNPs to remediate Cd pollution and simultaneously produce Se-enriched functional wheat. Full article

Cyclodextrins (CDs) offer a promising solution for enhancing the aqueous solubility of various hydrophobic molecules and facilitate their transport and delivery. Although CDs possess inherent molecular recognition capabilities, their derivatization is often essential to augment solubility and functional performance. A promising strategy involves the grafting of cyclodextrins onto polysaccharides. These hybrid systems combine the molecular recognition of CDs with the structural stability and versatility of biopolymers, yielding advanced materials suitable for biomedical and environmental applications. This review provides a comprehensive overview of CDs, focusing on their unique structural characteristics and their ability to form host-guest inclusion complexes with various hydrophobic molecules. The diverse methodologies used for CD modification and their immobilization onto polysaccharide backbones are described. Furthermore, the multifaceted applications of these grafted materials are explored. While in the pharmaceutical field these systems serve as advanced drug delivery platforms to improve the bioavailability and stability of hydrophobic therapeutic agents, in the environmental sector they demonstrate exceptional efficiency in wastewater treatment, acting as potent sorbents for the removal of organic pollutants and heavy metals. By bridging fundamental chemistry with practical applications, this review highlights the potential of CD-polysaccharide hybrids as sustainable solutions to pressing clinical and ecological challenges. Full article