Water, Air, & Soil Pollution最新文献

Bulk titanium dioxide (TiO₂) has been actively used in wastewater treatment to remove organic compounds. However, it suffers from low utilization of the light spectrum and rapid charge recombination. In this work, a binary oxide nanocomposite (CdO/TiO₂), also denoted as CT was employed to overcome the limitations of bulk TiO₂ in reactive black 5 (RB-5) degradation. The CdO/TiO₂ nanocomposite was prepared through a facile sol–gel method. The intact adhering of CdO on the TiO₂ surface has substantially enhanced the CT’s bandgap alignment, consequently enhancing the light absorption ability of CT up to the visible region. The doping of CdO onto the TiO₂ induces smooth transportation of photogenerated charge carriers, thus suppressing undesirable charge recombination. Consequently, a 3.3-fold increment (94.49%) of RB-5 degradation performance was observed compared to the pristine TiO₂. CdO/TiO₂ could be used as a catalyst for at least four cycles without significant change to the crystallinity and catalytic activity.

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The introduction of microbial inoculant has potential to enhance the vermicomposting process of organic wastes, yet the synergistic mechanism between microbial inoculant and earthworms in sewage sludge vermicomposting remains unclear. Herein, a native Bacillus cereus (B. cereus) strain C3 was isolated from naturally stacked sewage sludge. Four treatments were established: sludge without any addition (CK), sludge supplemented with the B. cereus C3 (SB), sludge supplemented with the earthworm Eisenia fetida (SE), and sludge supplemented with both the earthworms and B. cereus C3 (SEB). Inoculation with B. cereus C3 significantly reduced pH, electrical conductivity, organic matter and urease activity in the resulting vermicompost, while increasing total nitrogen, total phosphorus, and total potassium levels and boosting earthworm weight by 13.20%. The addition of B. cereus C3 lead to marked increase in the relative abundance of the phylum Firmicutes in the compost and vermicompost of SB (23% increase) and SEB (24% increase) groups, which was primarily attributed to the increased relative abundance of the genera unclassified Lachnospiraceae and Lactobacillus. Bacterial taxa involved in carbohydrate degradation (Lactobacillus, Bacteroides, unclassified Lachnospiraceae, norank Muribaculaceae, Flavobacterium, Bifidobacterium, and Brevundimonas) were enriched in the vermicompost of SEB group, exhibiting a 5.97% higher abundance than the SE group. Notably, Lactobacillus, norank Muribaculaceae, and Bifidobacterium appeared beneficial to earthworms. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the carbohydrate metabolism in the SEB group was enhanced by 20.50% compared to the SE group. Canonical correspondence analysis identified pH as the key factor influencing earthworm growth and bacterial community composition. This study highlights B. cereus C3 as a promising microbial inoculant in sludge vermicomposting and provided a deeper understanding on the synergistic mechanism between microbial inoculant and earthworms.

Groundwater contamination by uranium, largely controlled by lithological and geogenic factors, has emerged as a significant public health concern due to its dual radiological and chemical toxicities. This study quantifies uranium concentrations in groundwater across the geologically diverse Ladakh region of the northwestern Himalayas, India, employing an LED fluorimeter (LF-2a). The predominant role of groundwater in meeting drinking, household, and agricultural water demands highlights the importance of evaluating uranium contamination and its potential implications for human health and food security. A total of 73 groundwater samples were analyzed, yielding an average uranium concentration of 2.6 µg/L. Only one sample exceeded the United States Environmental Protection Agency permissible limit of 30 µg/L, while all measured concentrations remained below the Atomic Energy Regulatory Board (India) guideline value of 60 µg/L. Radiological dose estimation revealed that males exhibited higher exposure levels (15.71%) than females, particularly among older age groups, followed by children and infants. Among all tissues, the Lung and Stomach exhibit the highest dose across every age-group. Chemical risk assessments showed no non-carcinogenic concerns, with all exposure levels of in lifetime average daily dose remaining far below the reference limit of 4.4 µg/kg/day suggested by Atomic Energy Regulatory Board. The physicochemical results also suggest that spring water‒naturally low in dissolved salts and largely sourced from snow melt, is the safest option for drinking, while well and hand-pump water carries higher ionic content and possible contamination. Overall, the findings underline the importance of ongoing groundwater monitoring and holistic risk assessments to protect safe drinking water and public health across the Himalayan region.

Detecting pathogenic viruses in seawater presents significant challenges due to their typically low concentrations and the transient nature of contamination events. To address these challenges, this study evaluates passive sampling (PS) as a semiquantitative methodology for viral surveillance in seawater, focusing on human adenovirus (HAdV), norovirus GI (NoVGI) and GII (NoVGII). To optimize the approach, nylon and nitrocellulose membranes were compared, with nylon demonstrating greater consistency and reliability. In Barcelona, across 14 sampling events, 6 of them during combined sewer overflow (CSO) events, PS (n = 51) was assessed against grab sampling (n = 21) coupled with ultrafiltration (UF). Using PS, HAdV, NoVGI, and NoVGII were detected in 100%, 62.5%, and 75% of non-CSO events, respectively, outperforming UF, which detected these viruses in only 37.5%, 25%, and 37.5% of the same events. PS was applied during CSO events at both the CSO discharge point and at a nearby bathing site. As expected, the sampler deployed at the discharge point detected higher viral loads of HAdV, NoVGI, and NoVGII. However, viral genomes were also detected at the bathing site. Target enrichment sequencing of seawater vertebrate-infecting viruses conducted on PS samples, identified vertebrate viral pathogens, including members of the Circoviridae, Parvoviridae and Picornaviridae families, showcasing the extensive viral diversity in seawater due to fecal contamination. This study emphasizes the risk of viral exposure when seawater is impacted by CSO and the potential of PS as a robust tool for seawater viral surveillance, offering enhanced sensitivity and utility for quality management and public health risk assessment.

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Anthropogenic contamination of Cd(II) and phosphate becomes a crucial environmental issue on a global scale. In the current study, a promising Ca/pyro-hydrochar (Ca/Py-HyC) was fabricated based on invasive species biomass of Amaranthus retroflexus and Pomacea canaliculata shell to remove Cd and phosphate. According to the non-linear fitting results of Langmuir isotherm model, the adsorption capacity of Cd(II) and phosphate achieved 717.77 mg/g and 623.37 mg/g, respectively, which greatly exceeded the documented biochar/hydrochar based materials. Ca/Py-HyC showed an excellent adsorption performance in a wide range of pH (4.0 – 8.0) and ionic strength (0 – 0.5). Precipitation was the primary adsorption mechanism, which may further reduce the bioavailability of the contaminants and facilitate their recyclability and regeneration of the metal and nutrient resources. According to life cycle assessment, in comparison with Ca/PyC, and Ca/HyC, Ca/Py-HyC exhibited the lowest overall environmental impacts in term of per kg adsorbent, particularly in the categories related to ecosystems. Economic analysis suggested that the removal costs were 0.02 $/Cd kg and 0.05 $/P kg. Thereby, as a sustainable and eco-friendly functional material, Ca/Py-HyC may provide a strategy which can not only create net revenue, but also achieve optimization benefits in both eco-environmental and economic aspects.

This study synthesized hydroxyapatite (HAP) from oyster shells using hydrothermal and mechanochemical methods for the efficient adsorption and removal of cadmium from water. Batch adsorption experiments and characterization techniques were employed to comparatively analyze the differences in cadmium adsorption performance and mechanisms between the HAP synthesized for 6 and 12 h using the hydrothermal method (H6 and H12) and mechanochemical method (M6 and M12), respectively. The results showed that H6 had a smooth surface and higher crystallinity, while M6 had smaller crystallite sizes, a more developed mesoporous structure, and a significantly higher specific surface area than H6. The pseudo-second-order kinetic model and Freundlich adsorption isotherm model best fitted the cadmium adsorption curves for both types of HAP, indicating that the adsorption process is dominated by chemical and multilayer adsorption. The theoretical maximum adsorption capacities of H6 and M6 were 302.38 mg·g^-1 and 429.63 mg·g^-1, respectively. M6 exhibited stronger pH adaptability and greater resistance to cationic interference. Adsorption thermodynamics studies revealed that cadmium adsorption by HAP is a spontaneous endothermic process, and the surface disorder degree of H6 was higher than that of M6. Based on semi-quantitative analysis of mechanism contribution, precipitation, ion exchange, and complexation were the main adsorption mechanisms for both H6 and M6, accounting for 94.46% and 93.34%, 5.41% and 6.60%, and 0.13% and 0.06% of the total adsorption capacities, respectively. In summary, the HAP synthesized by mechanochemical methods demonstrated better environmental adaptability and adsorption performance; its rich mesoporous structure and large specific surface area endowed it with significant potential.

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This study systematically investigated the influence of the placement position of lanthanum-modified bentonite (LMB) on its efficacy in controlling sediment phosphorus release and elucidated the underlying mechanisms. Our results demonstrated that surface capping of LMB at the sediment-overlying water interface (SWI) effectively controlled sediment phosphorus release to the overlying water (OW), primarily through the passivation of diffusive gradients in thin films (DGT)-labile phosphorus in the upper sediment layer. Notably, the effectiveness of LMB showed a strong dependence on sediment burial depth. The efficiency of LMB in controlling the release of sedimentary phosphorus to OW diminished as the capping layer became buried by accumulating sediments, with this inhibitory effect progressively intensifying as sediment burial depth increased until complete functional loss occurred. However, stratified LMB application effectively mitigated the adverse effects of sediment burial on its controlling efficiency for phosphorus release from sediment to OW, with enhanced performance observed when a portion of the LMB layer was maintained above the SWI. Additionally, incorporating LMB into sediment through mixing effectively controlled sedimentary phosphorus release into OW. Mechanistic studies revealed that both LMB stratified capping and amendment approaches shared a common working principle: the passivation of DGT-labile phosphorus in the upper sediment layer. Collectively, these findings demonstrate that both stratified LMB application and LMB-sediment mixing effectively mitigate the negative impact of sediment burial on the control of phosphorus release from sediment into OW.

Bio-inspired synthesis of semiconducting nanoparticles has drawn extensive attention due to its eco-friendliness and suitable perspective. The current study is aimed at the synthesis of visible light-active ZnO nanoparticles using an aqueous extract of bio-waste of mango seeds to unveil their photocatalytic and antimicrobial potentials. The as-prepared ZnO nanoparticles showed a high degree of purity and crystallinity with 45.90 nm of average size as confirmed by XRD results and demonstrated excellent optical absorbance in the visible range. Furthermore, the FESEM and TEM investigations revealed the spherical to polygonal morphology of ZnO nanostructures. The BET analysis revealed a specific surface area of 10.44 m²g^-1, with a pore volume of 0.0042 cm³ g⁻¹ and an average pore size of 7.34 nm for ZnO NPs. The photocatalytic capacity of the green synthesized ZnO nanoparticles was investigated against the photodegradation of Brilliant Cresyl Blue (BCB) dye while antimicrobial potential against Escherichia coli (E. coli), a gram-negative bacterium and Bacillus subtilis (B. subtilis), a gram-positive bacterium, and demonstrated good antimicrobial activity against both bacterial strains with a clear zone of microbial inhibition. 88.25% of BCB dye degradation at the optimized experimental conditions of dye concentration, photocatalyst dose, and pH(7.00) within 120 min of visible light illumination was observed with a degradation rate of 0.0159 min⁻¹, and the ZnO nanoparticles retained ~ 80% photodegradation efficiency after the fourth cycle of reuse. Moreover, the scavenger study results confirmed that the hydroxyl radicals were the key active species participated in the degradation of BCB dye. Therefore, the reported ZnO nanoparticles are potentially excellent photocatalysts as well as antimicrobial agents which can be effectively utilized for the environmental remediation purposes.

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Water-soluble fertilizers, although widely used to enhance crop productivity, often lead to environmental pollution due to their rapid nutrient loss. To address this issue, coated biochar-based fertilizers have gained attention for improving nutrient use efficiency and reducing environmental impacts, with their performance greatly depends on the formulation of the encapsulating materials. Biopolymers such as starch offer a biodegradable alternative to synthetic polymers, while soybean wax provides an environmentally-friendly and highly hydrophobic coating capable of enhancing the controlled-release behaviour. Together, these materials present a promising strategy for developing more sustainable controlled-release fertilizer formulations. In this study, a double-layered coated biochar-based fertilizer was synthesized using corn starch as the inner coating and soybean wax as the outer layer to enhance the nutrient release performance and support sustainable agriculture. The double-coated formulation improved the water retention and slowed the nitrogen release as compared with the uncoated fertilizer, following a zero-order kinetic mechanism. These controlled-release characteristics enhanced the plant performance as evidenced by the increased okra height. Overall, the corn starch/soybean wax coating demonstrated a strong potential for reducing the nutrient loss while promoting crop growth.

This study provides a thorough assessment of zeolite nanoparticles as efficient adsorbents for the desalination of field-treated generated water from hydrocarbon reservoirs. Based on SEM-EDS and FTIR tests, the nanomaterials had a mostly spherical shape (50 - 90 nm), an Al/Si ratio of about 1:3, and framework vibrations that showed an active aluminosilicate lattice. The FTIR spectra showed that the Si–O–T (T = Si or Al) and O–H vibrations changed after ions were adsorbed. This was direct spectroscopic proof of chemisorptive cation exchange. Batch adsorption tests with doses of 2 - 8 g/L and contact periods of up to 120 minutes showed that the best salt removal was 90–95% at 6 g/L and 2 hours, with a maximum adsorption capacity of 100 - 120 mg/g. The kinetic analysis showed that adsorption followed the pseudo-second-order model (R² > 0.99), which meant that chemisorption was the slowest step. The equilibrium data fit the Sips isotherm, which meant that there were different surface sites with high binding affinity. The nano-zeolite adsorbents showed great cyclic stability, keeping their removal efficiency at over 88% after five adsorption-desorption cycles and 78.5% after ten cycles when regenerated with a simple 10% (w/v) NaCl brine wash. The regeneration process works at 80°C and normal pressure, which uses a lot less energy than thermal or membrane desalination methods like MED or RO. The results show that nano-zeolite adsorption is a technically possible, energy-efficient, and environmentally friendly way to lower the salinity of generated water. The findings enhance the existing knowledge of nanostructured aluminosilicates in resource-water management and establish a basis for pilot-scale field application and lifecycle optimization in oil and gas operations.