Water, Air, & Soil Pollution最新文献

Microplastics (MPs) have grown to be a common environmental issue because they are frequently found in both aquatic and terrestrial ecosystems. Their resistance to degradation allows them to endure for decades or even centuries, posing a threat to aquatic life and human health. Therefore, designing effective strategies to remove them from the environment is one of the most urgent environmental concerns. We has focused on the current abundance of MPs in different water bodies in this review article, and investigated the developments of catalysts, including eletrocatalysts, photocatalysts, and biocatalysts, for removing MPs. Among them, photocatalysis and microbial degradation technologies are widely investigated, showing promise at laboratory scale for the transformation of MPs to water-soluble hydrocarbons and carbon dioxide, offering the potential for long-term water security and ecological stability, and deserving further attention. Additionally, the challenges involved in the MP treatment and future prospective have been emphasized.

Nitrate contamination in drinking water is now gaining global attention because of its potential effect on human health. In this study, nitrate concentrations and their potential sources in groundwater and surface water were investigated using hydrochemical and isotopic methods. The physical parameters were measured in-situ using multi parameter meters; major ions, stable isotopes (δ²H and δ¹⁸O of H₂O) and δ¹⁵N and δ¹⁸O of NO₃⁻ were measured using the Ion Chromatography, laser spectrometry and titanium (III) reduction method respectively. The results indicate that the dominant water type is Ca-Mg-HCO₃, followed by the Ca–Mg–Cl hydrogeochemical facies. The plot of NO₃⁻/Cl⁻ against Cl⁻ revealed that the dominant sources of NO₃⁻ in the groundwater are manure/sewage with few traces from soil inputs. Meanwhile the plot of δ²H-H₂O against δ¹⁸O-H₂O showed that rainfall is the main source of groundwater recharge with few groundwater samples showing evidence of recharge from an enriched source (Black Volta River). The plot of δ¹⁸O – NO₃⁻ against δ¹⁵N – NO₃⁻ suggests that a significant percentage of nitrate is from manure and sewage, followed by the soil zone, hence leading to nitrification and denitrification being important biological processes affecting NO₃⁻ concentrations in groundwater in the study area. The stable isotope mixing model suggests manure contributed a mean proportional contribution of about 74% of NO₃⁻ to groundwater in the study area, while soil nitrogen contributed 10%. The Nitrate Pollution Index (NPI) suggests that about 80.2% of water samples were pollution free, while anthropogenic activities resulted in about 8.3% of the pollution index. Since most samples with lower nitrate pollution indices were observed around recharged areas and increased toward the discharge points, our study suggests the possibility that recharge areas of the water was free or lowest in nitrate contamination.

This study investigates the photocatalytic degradation capabilities of Co₃O₄ synthesized via the sol–gel method for 1,2,4-trichlorobenzene under visible light. Characterization of the composites through scanning electron microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) confirmed the formation of a cubic-phase structure. The photocatalytic performance of the synthesized Co₃O₄ was rigorously evaluated using the Langmuir–Hinshelwood model across various operational parameters, including catalyst dosage, initial pollutant concentration, reaction temperature, pH, and the presence of impurities such as humic acid, hydrogen peroxide (H₂O₂), and surfactants. Optimal conditions for the degradation process were determined to be a catalyst dosage of 2.0 g/L, an initial 1,2,4-trichlorobenzene concentration of 7.5 mg/L, and a reaction temperature of 30 ℃. Degradation efficiency was found to decreasenear neutral pH levels. Notably, the presence of humic acid had a negative impact on the degradation rate, while cationic surfactants and H₂O₂ served to enhance the photocatalytic process. Additionally, the degradation pathway and mechanism of 1,2,4-trichlorobenzene were predicted and validated, providing essential insights into its photocatalytic conversion. These findings underscore the effectiveness of synthesized Co₃O₄ in the photocatalytic degradation of 1,2,4-trichlorobenzene and highlight the significant influence of environmental conditions on the degradation efficiency. This study offers valuable insights for developing efficient photocatalytic systems for treating chlorinated organic pollutants under visible light.

Hybrid composites based on ferrite nanoparticles have shown their effectiveness in the heterogeneous Fenton process due to the multiple properties such as ferromagnetism and biocompatibility. In this work, Magnetite (Fe₃O₄) nanoparticles are synthesized and dispersed thanks to the anchoring plasma-created sites onto water hyacinth fibers used as the catalytic support. The obtained composites were characterized by XRD, FTIR, SEM/EDX, and the magnetization properties were assessed at different temperatures (20 K, 150 K, and 300 K). The results reveal uniform dispersed nanorod-shaped particles covering the entire surface of the biomass with the saturation magnetization at 15 emu.g⁻¹. The Fenton degradation process was optimized in terms of pH, mass, contact time and pollutant concentration, thus the catalytic performance achieved on two organometallic model pollutants, namely merbromine (MB) and the green complex of naphthol B (NGB) give degradation efficiencies of 97.01 and 99.70% respectively. The Langmuir–Hinshelwood kinetic model better describes the phenomenon where adsorption is the rate-limiting step given the high reactivity of generated species. The trapping species experiments show that besides hydroxyl radicals that contribute mainly to the degradation, other species such as superoxide and hydroperoxyl radicals are involved in the overall degradation mechanism. The obtained material is effective in the plasma-Fenton coupling process and the leaching test confirms their stability after four reuse cycles with the degradation rate greater than 85.10%.

The rhizosphere is an important interface for soil–plant interaction and a significant zone for the uptake and removal of heavy metals from soils. This study assesses the level of heavy metals contamination in the rhizosphere of plants growing at a decommissioned tailings dam in Ghana. Concentrations of heavy metals [Arsenic, Cadmium, Copper, Iron, Manganese and Zinc] and physicochemical parameters [pH, conductivity, total dissolved solids, phosphate, nitrate, sulfate] of rhizospheric soils were determined. The assessment of the extent of rhizospheric contamination was conducted using the enrichment factor (EF), geo-accumulation index (I_geo), and pollution load index (PLI). Factor analysis unveiled the most relevant heavy metal contributors to rhizosphere contamination. Results indicate moderate to significant enrichment of Cd (1.72 – 8.28) and Mn (1.70 – 8.32) in the rhizosphere. The PLI showed that rhizospheres are heavily polluted (18.8 – 29.6) and thus require remediation. Principal component analysis revealed significant Cd, As, and Fe contamination in the rhizosphere accrues from anthropogenic or mining activities. The levels of heavy metal ions in the rhizosphere suggest that Mimosa pudica, Centrosema pubescens, Leucaena leucocephala, Pueraria phaseoloides, and Tridax procumbens could be investigated as candidates for phytostabilization of mine tailings. This study emphasizes the importance of effective remediation and continual tailing dam monitoring before and after decommissioning to avert the spread of heavy metal contaminants.

The distribution and composition of microplastics (MPs) in sediments provide a useful reflection of overall MP pollution for urban river systems. Sediment samples were collected from the Jinjiang River, the main tributary of the Minjiang River, to articulate the sources, distribution, and risk status of MPs. The results showed that the MPs in Jinjiang sediments were composed of polypropylene (PP), polyethylene (PE), polyethylene glycol terephthalate (PET), polystyrene (PS), and Rayon, with per kilogram of dry sediment (n/kg) ranged from 21 to 924 particles, and PP and PE were accounted for more than. MPs varied in colour, shape and size (100–5000 µm), although those observed were predominantly green, fragmented and about 1,000–5,000 µm. The dominant sources of MPs in sediments could be domestic waste and laundry effluents. The risk assessment for MPs showed that upstream and downstream were at moderate risk, while midstream was at low risk. This study can provide a reference for the management and control of MP pollution in urban rivers.

Algae have emerged as a promising approach for the removal of heavy metals from wastewater due to their low-cost, efficient, and eco-friendly characteristics. The unique structural and biochemical properties of algae enable them to remove heavy metals from wastewater using various mechanisms, including physical adsorption, ion exchange, complexation, precipitation, phycoremediation, and bioaccumulation. Algal modification techniques such as pre-treatment, immobilization, and genetic modification are also discussed as means of enhancing the efficiency and specificity of heavy metal removal. Additionally, the regeneration of algal biomass is presented as a sustainable solution to the issue of algal disposal.

The design and synthesis of semiconductor photocatalysts by morphology control is a key step to improve photocatalytic performance. Herein, a series of NiO/ZnO composites with core–shell nanostructures were synthesized by in-situ growth of 2D NiO nanosheets onto 1D ZnO nanorods. The chemical composition, morphology, and optical properties of the synthesized composites were characterized and discussed in detail. The obtained NiO/ZnO composite exhibited enhanced photocatalytic performance with 94.3% degradation efficiency for tetracycline (TC) within 20 min illumination, which was mainly attributed to the heterostructure formed by the excellent interface contact of the nanostructure, thereby inhibiting the recombination of photogenerated charges. Additionally, the as-synthesized photocatalyst shown satisfactory photocatalytic activity and TOC removal efficiency in cyclic experiments. The present work provides a novel insight for the design of heterojunction photocatalysts with multidimensional nanostructures and environmentally friendly applications.

Effective removal of ammonia, nitrate, and intermediate nitrite is a challenge faced by highly dissolved oxygen (DO) recirculating aquaculture systems (RAS). This study investigated the effect of DO concentrations (Group A, DO 3.15 ± 0.12 mg/L, Group B, DO 4.43 ± 0.15 mg/L, Group C, DO 6.52 ± 0.35 mg/L, Group D, and DO 7.86 ± 0.55 mg/L) on the simultaneous nitrification and denitrification (SND) of aquaculture seawater using poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as a biofilm carrier and solid-phase denitrification (SPD) carbon source. Ammonia and nitrate were simultaneously removed in all the PHBV-supported SPD systems. Ammonia in Group C had the highest removal rate (5.72 mg/(L·h)), whereas nitrate and nitrite in Group A were completely removed at 4 and 5 h, respectively. The continuous release of PHBV provided carbon sources for denitrification. High throughout sequencing showed that Proteobacteria, Bacteroidetes, Desulfobacterota, and Chloroflexi at the phylum level, and Marinobacter, Shewanella, and Pseudomonas at the genus level exhibited unique relative abundances under varying DO concentrations. The nitrification genes in Group C showed the highest expression. Denitrification genes in Group A were enriched. The relative expression of nitrogen-transforming genes further demonstrated the results for water quality and the microbial community. DO concentration affected the efficiency of the nitrogen transformation pathway in the PHBV-supported SPD system.

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Phosphorus and chlorophyll-a are considered the main responsible for the eutrophication of lakes and water reservoirs around the world. Monitoring of the physical, chemical, and biological variables of water provides the basis for environmental management and protection policies. The purpose of this study was to evaluate the level of eutrophication in waters of hydropower plant reservoirs, considering the Espora hydropower plant as model system, by applying the trophic state index. In this context, water samples were collected at 34 sampling points in four different periods of the year. It was possible to conclude that the study reservoir shows fluctuations in relation to the trophic state, influenced by the rains, which carry the phosphorus existing in the drainage basin into the reservoir. Statistical analysis showed the existence of a weak and negative correlation, dismantling the idea that the enrichment of the waters with phosphorus does not influence the increase in chlorophyll-a concentration to the point of causing eutrophication. It is expected that the results of this study can assist in the management and monitoring of lakes and reservoirs in different countries.

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