Water, Air, & Soil Pollution最新文献

A self-made equipment was used to study the electrokinetic remediation of copper-contaminated soil. The speciation transformation rules of copper (Cu) at different remediation times and voltages were explored. Experimental parameters such as electrolyte pH value, soil pH value, soil moisture content, and soil conductivity were measured and analyzed. The Community Bureau of Reference (BCR) sequential extraction procedure was applied to measure the speciation of Cu in soil. Results showed that after the electrokinetic remediation, the experimental parameters changed to varying degrees, which had a certain impact on the removal and transformation of Cu in the soil. The acidic region in the soil was more conducive to the speciation transformation of Cu than the alkaline region. Higher moisture content and larger electrical current accelerated the migration of ions in the soil. Results of the BCR sequential extraction method revealed that the ratio of EX-Cu content increased from 37.50% to 50.60%, the ratio of RED-Cu content decreased from 12.25% to 10.50%. The proportion of OXI-Cu content initially increased and then decreased, while the ratio of RES-Cu content decreased from the anode to the cathode. However, due to the stable properties of OXI-Cu and RES-Cu, the proportions of OXI-Cu and RES-Cu changed minimally during the process of remediation.

Air pollution is a life-threatening public health issue, with millions of premature deaths caused by air pollution every year. To reduce health hazards, environmental damage, and financial losses, effective monitoring and management are crucial. Though the air quality prediction and forecasting have been done since the 1980s, there are significant challenges involved due to their complexity and global impact. Apart from manual AQI measurements by government agencies, novel methods like deep learning techniques can be used to predict AQI in both scalable and cost-effective ways. Deep learning techniques can be accessed using large datasets and detection using nonlinear relationships. A hybrid CNN–LSTM model was developed and trained with AQI datasets (2015–2024) to address challenges in spatial and temporal pattern recognition. The model achieved remarkable accuracy, exceeding existing architectures such as LSTM, GRU, CNN, and WLSTM. The proposed hybrid CNN–LSTM model had outstanding predictive performance, shown by an accuracy of 96.8%, a high R² of 0.92, and low error rates (RMSE = 8.66–13.5, MAE = 0.0514) over datasets from 2015 to 2024. These results confirm the model's robustness and generalization ability for AQI prediction. The findings demonstrate the model's effectiveness in real-time air quality monitoring, assisting policymakers and environmental agencies in making educated decisions for sustainable pollution control.

Metal contamination from mining, heavy traffic, and illegal mining pose a serious environmental threat, especially in urban and peri-urban areas where soils near roadsides and mine-adjacent zones are exposed to pollutants. Unregulated mining worsens contamination, affecting ecosystems and agricultural lands. Although grasses are often considered ineffective in multi-metal contaminated soils, Eragrostis curvula shows promise as a hardy native species for phytoremediation in such environments. This study examined whether the E. curvula cultivars, Ermelo and Agpal, showed potential to reduce metal concentrations in contaminated soils. Metal concentrations in pre-planting soils, post-harvest soils, and plant tissues were determined, and bioconcentration factors were calculated for samples from all soil collection sites. Pre-planting soils collected from Jameson Park, Kaydale, and Rensburg had high concentrations of iron (36 000–50 000), manganese (800–900), nickel (48–75), strontium (10–20), zinc (71–79), chromium (117–224), and barium (114–117) mg/kg, with a pH of 4.6–5.0 and total cation concentration of 4.7–10.9 cmol/L. The Ermelo cultivar accumulated iron (3 289–6 149), manganese (185–522), nickel (13–26), strontium (9–10), zinc (46–64), chromium (55–85), and barium (36–71) mg/kg, while the Agpal cultivar accumulated corresponding concentrations of 3 092–5 216, 136–488, 4–32, 8–26, 48–57, 21–122, and 37–77 mg/kg. The iron (9 000–32 000), manganese (200–809), nickel (31–63), strontium (8–16), zinc (33–73), chromium (83–137), and barium (73–113) mg/kg of post-harvest soils decreased significantly, while the pH increased to 5.2–5.6 and the total cation concentration was 4.3–7.2 cmol/L. The cultivars had varied bioconcentration factors for iron (0.06–0.15), manganese (0.12–0.57), nickel (0.08–0.53), strontium (0.37–1.10), zinc (0.51–0.93), chromium (0.10–0.89), and barium (0.33–0.68) indicating more efficient accumulation of zinc and strontium, while iron and chromium were taken up to a lesser extent. The presence of E. curvula cultivars in the soils promoted the proliferation of plant growth-promoting bacterial genera, including Bacillus, Pedobacter, Pseudomonas, and Flavobacterium, in the post-harvest soils. The activity of these bacteria and their associated soil enzymes may have contributed to the ability of E. curvula to maintain growth and persist under metal-contaminated conditions. These results highlight E. curvula’s potential as a phytoremediation agent in multi-source metal-polluted soils.

Urban runoff containing high amounts of nutrients like phosphorus (P) is a well-established driver of surface water eutrophication. In residential areas, a primary source of nutrients is derived from leaf litter. P contained in leaves is leached and transported by stormwater from source to stream. The majority of P leached from leaf litter is in the dissolved phase, which can be difficult to remove using conventional treatment practices, leaving source control as the most viable option. Additional tools are needed to help forecast how different tree species may improve or hinder contributions of nutrients to runoff. For this reason, ten street tree species that are common throughout the contiguous U.S. were chosen to evaluate the effect of species on leachable P from tree leaves using laboratory experiments. After 48 h of exposure to water, the amount of P released ranged from 2.16 mg P g⁻¹ leaf for Silver Maple to 0.03 mg P g⁻¹ leaf for Hackberry. More than half of the P was lost in the first 12 h for eight of the ten tree species, making guided source control important to reduce inputs to surface water from key locations. Results were used to identify ‘hotspots’ of P leaching in Madison, WI and can be used to assess current street tree inventories that can then guide management to areas with the highest nutrient reduction potential and inform urban foresters who may wish to tailor future planting scenarios that minimize nutrients in runoff.

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The aim of this work was to investigate the remediation performance and mechanism of the composites based on alkaline minerals and agricultural wastes to acidified soil. The wollastonite-sodium silicate-biochar composite (Ca-C-Si) and hydroxyapatite-sodium silicate-biochar composite (P–C-Si) were prepared and applied to the remediation of acidified yellow soil with a pH of 4.70 through pot Chinese cabbage experiment. As the dosage of Ca-C-Si and P–C-Si increased from 0.5% to 2.0% of the acidic yellow soil, significant changes in soil characteristics were observed compared to the control. The pH value increased by a maximum of 0.98 and 2.09 units, respectively; the exchangeable acidity, exchangeable hydrogen, and exchangeable aluminum decreased by the maximum of 79.73% and 94.52%, 59.26% and 82.72%, 85.56% and 97.89%, respectively; and the cation exchange capacity and base saturation increased by the maximum of 66.07% and 133.93%, 57.2% and 63.7%, respectively. However, the fresh weight and dry weight of Chinese cabbage reached their maximum at a dosage of 1.5% for Ca-C-Si and 0.5% for P–C-Si, respectively. The dosage of materials needed to be optimal, achieving a balance between soil improvement and crop growth. Infrared spectrum, X-ray diffraction pattern, pH and chemical composition showed that the rape straw was converted to biochar under high temperature and anoxic conditions. The materials exhibited better alkalinity, contain essential nutrients for plant such as calcium, silicon, phosphorus and potassium. The functional groups like hydroxyl and carboxyl on biochar could dissociate to form negatively charged sites, which improved cation exchange capacity and neutralize hydrogen ions. This study demonstrates the improvement effect and mechanism of the two composites on acidic yellow soils, which provides practical guidance for the application of materials in soil remediation.

This research presents a pioneering approach that combines hydrocyclones with electrocoagulation (EC) to improve desalination pretreatment processes. The study integrates hydrocyclones' centrifugal force for particle separation with EC’s ability to destabilize and aggregate suspended solids, reducing fouling in RO systems without chemical additives. Seawater samples from the Al-Khobar coastline in the Eastern Region of Saudi Arabia were analyzed for particle size distribution, salinity, and viscosity, which guided the experimental design. Electrocoagulation experiments demonstrated that using aluminum/graphite electrodes effectively enlarged salt particle size from 0.81 nm to 2.96 µm, making them more suitable for hydrocyclone capture. Computational fluid dynamics (CFD) simulations were validated against published experimental data to optimize hydrocyclone design following EC experiments. Three industrial-scale hydrocyclones were analyzed using validated CFD simulation settings, with results showing removal efficiencies of 59%, 70%, and 41% for 3 µm particles in hydrocyclones H₁, H₂, and H₃, respectively. The integrated EC-hydrocyclone system effectively enhanced particle removal, which can reduce fouling potential and improve water quality for RO processes. The proposed approach can also reduce chemical usage in desalination processes, improving sustainability and environmental performance and significantly advancing the transition toward a circular economy and eco-friendly desalination practices.

Traditional aluminum and iron salt coagulants are widely used, but the residual metal ions affect the safety of water quality. In this study, a new starch-based composite coagulant, etherified starch composite titanium polysilicate (PSFZ), was prepared by etherification and thermal polymerization reaction using natural corn starch as raw material. In the optimization of the preparation process, four parameters, namely, the synthesis pH of polysilicic acid, the ratio of starch to titanium polysilicate, the reaction temperature and time, were focused on, and after determining the optimal ranges of the factors through one-way experiments, the process was optimized by using orthogonal tests, and the microplastic removal rate was taken as the core evaluation index. Characterization results showed that PSFZ is a polycrystalline phase/amorphous composite polymer, and its three-dimensional mesh structure has a large specific surface area, which endows it with excellent sweeping net trapping and adsorption bridging performance. The experiments showed that the removal rate of humic acid (NaHA) reached 84.57% when the dosage of PSFZ was 3.5 mg/L, and the microplastic removal efficiency peaked at 4 mg/L (95.51%). The mechanism study showed that the hydrolysis of titanium polysilicate generated polynuclear hydroxyl complexes, while the quaternary ammonium group (N⁺) in starch neutralized the negative charge on the surface of microplastics through electrostatic interaction; in addition, the three-dimensional network of polysilicate and the long-chain of starch synergistically interacted with each other, and efficiently removed the pollutants through the adsorption and bridging and the net-trapping and sweeping mechanisms.

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This paper focused on the resourceization of oil-containing waste white clay and fluid catalytic cracking (FCC) waste catalyst in the petrochemical industry. Through thermal desorption technology, the oil-containing waste white clay was pretreated to obtain purified waste white clay, and the FCC waste catalyst was pretreated by magnetic separation and recycling technology to get low magnetic agent. According to the composition of ceramic granules, the purified waste clay and low magnetic agent were mixed in a certain ratio to successfully prepare ceramic granules through the balling, preheating and calcination. The physical characteristics of ceramic granules were determined, and the results showed that when the ratio of purified waste clay to low magnetic agent was 9.5:0.5 and the sintering temperature was 1190 ℃, the bulk density, cylinder compression strength, water absorption rate, and loss on ignition of the ceramic granules were 649 kg/m³, 5.1 MPa, 14.6%, and 0.8%, respectively. The above performance was relatively excellent and the energy consumption during the preparation process was minimal, thus the obtained ceramic granules could be applied to the building materials industry. At a sintering temperature of 1140 ℃, ceramic granules exhibited high adsorption efficiency, with an adsorption rate of 34.4% after 24 h. Therefore, the as-prepared ceramic granules were expected to be used for the adsorption of pollutants in the water treatment industry.

The dilution technique and agricultural reuse of solar saltworks effluent represent a novel approach, capable of transforming an industrial byproduct into a source of nutrients, reducing dependence on synthetic fertilizers, lowering production costs, and mitigating the carbon footprint of agricultural cultivation. The objective of this study was to evaluate the sustainable use of solar salt pan effluent in forage sorghum cultivation, correlating soil attributes and plant physiological responses under different dilutions. The experiment was conducted in a randomized block design, in a 5 × 2 factorial arrangement. Factor 1 corresponded to dilutions of the effluent in rainwater (EC 1.5, 3.0, 4.5, and 6.0 dS m⁻¹), in addition to rainwater as a control. Factor 2 comprised two soil classes: Fluvisol and Ferrasol. Forage sorghum cv. Ponta Negra was grown in 20-L pots and irrigated twice weekly. Soil physical, water, and chemical properties were evaluated by multivariate analysis, while physiological parameters and shoot ionic composition were analyzed by univariate statistics. Effluent dilution promoted sustainable reuse, reducing Na input to the soil and providing K, Ca, and Mg. The soil classes exhibited antagonistic behavior: Fluvisol was associated with chemical fertility attributes, while Ferrasol was associated with physical, water, and degradation properties. Most physiological parameters remained unchanged, with modifications only in stomatal conductance and Mg (Ferrasol) and water use efficiency and K (Fluvisol). The results demonstrate that the dilution technique mitigates osmotic stress, constituting a sustainable strategy for sorghum cultivation in semiarid regions.

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Landfill leachate is a dark-colored, complex liquid formed by the percolation of water through municipal solid waste, containing diverse array of emerging contaminants. Reported concentrations include pharmaceuticals such as ibuprofen (2–1,500 µg/L) and carbamazepine (up to 800 µg/L), personal care products like triclosan (50–3,200 µg/L), pesticides (50–1,200 µg/L), phthalates such as Di(2-ethylhexyl) phthalate (up to 5.3 mg/L), polycyclic aromatic hydrocarbons (20–600 µg/L), polychlorinated biphenyls (0.1–50 µg/L), per- and polyfluoroalkyl substances (up to 6,200 ng/L), microplastics (10²–10⁴ particles/L), and endocrine disruptors such as bisphenol A (0.5–1,800 µg/L). These contaminants persist in the environment, resist natural degradation, and thereby posing significant ecological and health risks. The conventional biological treatments, including activated sludge and anaerobic digestion, achieve only partial removal (20–60% for pharmaceuticals; < 30% for per- and polyfluoroalkyl substances). Physico-chemical processes such as coagulation-flocculation, advanced oxidation, and membrane filtration provide higher removal rates (60–95%) but remain energy-intensive, costly, and prone to secondary pollution. There is no single treatment that ensures complete elimination, underscoring the inadequacy of traditional methods. Recent advances, including hybrid membrane bioreactors, advanced oxidation processes, and bioelectrochemical technologies, achieve more than 90% removal of selected contaminants. The study focuses on the occurrence and fate of emerging contaminants in landfill leachate, evaluates the performance of existing treatment technologies, and compares regulatory frameworks across different countries. The insights aim to guide the development of sustainable and integrated strategies for effective leachate management.

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