Search Results (201)

Dissolved organic matter (DOM) in the water column and sediments in coal mining subsidence areas considerably affects the carbon cycle and ecological environment. This study analyzed the spectral characteristics, material composition, and molecular transformation of DOM in the water column and sediments of a coal mining subsidence area in Huaibei, China, using ultraviolet–visible absorption spectroscopy, three-dimensional fluorescence spectroscopy combined with the parallel factor analysis (PARAFAC) model, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The DOM concentration (11.99 ± 4.73 mg/L) and the degree of DOM humification in the sediment were higher than those (9.54 ± 0.68 mg/L) in the water column. The PARAFAC model revealed three chemical components: fulvic acid–like, protein-like, and humus-like substances. DOM in the water column is primarily derived from endogenous inputs, characterized by low humification and high biological activity. In contrast, DOM in the sediments primarily originates from external inputs. FT-ICR MS analysis revealed that lignin-like (50.80–67.02%), protein-like (13.18–18.38%), and lipid-like (5.74–10.39%) components are the main DOM constituents in the water column and sediments, with lignin content in the water column (66.16%) being higher than that in the sediments (55.09%). Paired mass difference network analysis identified redox reactions as the predominant reactions in the water column and sediments, converting aldehydes or carbonyl compounds into acids or alcohols. This study elucidates the composition and transformation characteristics of DOM in the water column and sediments in coal mining subsidence areas, providing a scientific foundation for the protection and management of aquatic ecosystems. Full article

Pharmaceutical compounds, emerging medicinal residues, and personal care products (PPCPs) are ubiquitous in aquatic environments and are causing a serious global environmental problem because of their persistence, bioaccumulation, and harmful effects on the environment and human health. Conventional wastewater treatment technologies are sometimes not capable of removing them completely, causing persistent releases of biologically active micropollutants to surface water, groundwater, and drinking water systems. In this context, biomass-derived catalysts are a promising class of advanced materials for environmental remediation because of their sustainable and cost-efficient nature. The catalysts are composed of bio-residues, such as agricultural residues, forestry wastes, and other bioresources, that have tunable surface chemistry, high porosity, and can be activated and functionalized to increase their catalytic activity. This review summarizes recent advances in biomass-derived catalysts for the removal of pharmaceuticals and PPCPs from water. Special attention is given to synthesis methods, such as pyrolysis, hydrothermal carbonization, chemical activation, heteroatom doping, and metal or metal-oxide hybridization. The catalytic mechanisms of pollutant degradation, including adsorption, radical-based advanced oxidation processes, and non-radical electron-transfer mechanisms, are critically discussed. Moreover, the effect of key operating parameters, catalyst stability, and real wastewater test performance are studied. Sustainability aspects such as green synthesis routes, integration of circular bioeconomy, and life-cycle aspects are also emphasized. Finally, current issues like catalyst deactivation, scaling-up, and the lack of a full mechanistic understanding are identified, and future research avenues are suggested to enable the implementation of efficient, durable, and environmentally friendly catalytic systems for large-scale wastewater treatment applications. Full article

Confronted with severe global challenges, including water scarcity, excessive use of chemical fertilizers and pesticides, and heavy metal contamination in soils, conventional agricultural technologies exhibit marked limitations in integrated water–fertilizer management and non-point source pollution control. Leveraging their excellent water retention capacity, intelligent sustained-release properties, and environmental responsiveness, hydrogels offer innovative solutions to advance sustainable agricultural development. This review comprehensively outlines the fundamental types, crosslinking mechanisms, and key functional properties of hydrogels, with a focused discussion on their agricultural deployment as high-efficiency soil conditioners, fertilizer vectors, and pesticide carriers; it deciphers the microscopic water-holding mechanisms under the tristate water model, delineates the divergent water-uptake and retention behaviors between ionic and non-ionic hydrogels, and clarifies the cyclic water-holding and release mechanisms of hydrogels during soil amelioration. Thise paper further synthesizes hydrogel-enabled environmental remediation applications, in which heavy metals and pesticide residues in soils and aquatic systems are removed via functional-group coordination adsorption or photocatalytic degradation; concurrently, hydrogels have been shown to activate plant systemic immunity through calcium-signaling pathways, thereby inducing broad-spectrum antiviral defense responses. Moreover, hydrogels can be integrated into precision agriculture frameworks to enable real-time monitoring of crop physiological status and to support targeted irrigation and fertilization management. This work also evaluates the role of hydrogels in promoting seed germination, root system development, crop metabolic regulation, and stress resilience, while introducing tailored application strategies across distinct plant growth stages. Their documented economic advantages include water conservation, enhanced crop yields, reduced dependence on synthetic fertilizers, and lower labor costs. Nevertheless, the large-scale implementation of hydrogels continues to face multifaceted challenges—particularly poor degradability and latent ecological risks, as conventional polyacrylamide (PAM)-based gels resist soil mineralization and retain potentially neurotoxic monomers, leaving a critical gap in multi-annual field data concerning their non-target interference with native soil aggregate evolution, pore distribution, and rhizospheric carbon–nitrogen footprints. Mechanistically, many hydrogels with tensile strengths below 1 MPa are highly susceptible to three-dimensional network collapse under high-salinity osmotic shock and tillage mechanical stress, exhibiting a precipitous drop in water retention after more than three wet–dry cycles due to deficient long-term structural stability. Compounding these technical gaps are elevated production costs and low farmer adoption, driven by the absence of texture-specific performance thresholds—such as an available water increment ≥ 40% for sandy soils—and the lack of established life-cycle cost models and farmer incentive mechanisms for bio-based hydrogels. Moving forward, hydrogel technology should pivot toward materials innovation and cost-reduction engineering to broaden its applicability, employ ≥3-year, multi-habitat regional trials to delineate ecological benefit–risk boundaries, and ultimately position hydrogels as pivotal enablers of sustainable, green agricultural paradigms. Full article

Per- and polyfluoroalkyl substances (PFASs) are persistent synthetic chemicals of global concern. While most research has focused on their occurrence and toxicity, far less attention has been paid to their impacts on the global carbon cycle. This review synthesizes current evidence on how PFASs influence carbon cycling across soils, aquatic systems, and the atmosphere. In soils, PFASs alter organic carbon inputs by affecting plant biomass and root exudates and shift microbial community composition and enzyme activities, thereby modulating organic matter decomposition. In aquatic ecosystems, PFASs biologically impair carbon sequestration by inhibiting plankton, and abiotically interact with extracellular polymeric substances to prolong the cycling of dissolved organic carbon. The atmosphere acts as a key mediator as follows: thermal treatment of PFASs generates perfluorocarbons, potent greenhouse gases that exacerbate global warming and further disturb carbon cycling. Despite clear disruptive effects, major knowledge gaps remain. Future research should use quantitative structure–property relationship modeling to assess PFAS alternatives (e.g., PFHxS), and employ advanced molecular tracking (e.g., isotopic labeling, NanoSIMS) and machine learning to unravel nonlinear PFAS–carbon dynamics. Improved detection technologies are needed to identify greenhouse gas byproducts from PFAS thermal treatment. Ultimately, deploying high-resolution flux observation networks and integrating PFAS dynamics into Earth system models and carbon-accounting frameworks are critical for predicting carbon–climate feedback and supporting global carbon neutrality goals. Full article

Municipal wastewater is a major pathway for the continuous release of microplastics into aquatic environments, making the development of efficient and reusable capture materials essential for advanced water treatment. In this study, a multifunctional ZIF-67/g-C₃N₄/CS nanocomposite was designed by integrating cobalt-based zeolitic imidazolate framework ZIF-67 with graphitic carbon nitride (g-C₃N₄) and a chitosan (CS) biopolymer matrix. The novelty of this material lies in combining the high porosity and tunable surface chemistry of ZIF-67, the π-rich layered structure of g-C₃N₄, and the hydrophilic, amino-rich chitosan framework into a single adsorptive platform for simultaneous removal of chemically different microplastics. The nanocomposite achieved high removal efficiencies for polystyrene (PS), polypropylene (PP), and polyethylene (PE) microplastics with particle sizes of 20–25 μm, reaching 97.4%, 92.1%, and 90.3%, respectively, at pH 7.6 within 25 min. The higher affinity toward PS is attributed to additional π–π interactions between the aromatic PS chains and the conjugated domains of g-C₃N₄/ZIF-67, whereas PP and PE removal is mainly governed by hydrophobic adhesion, surface trapping, and interfacial interactions with the chitosan-supported porous framework. The equilibrium data were well described by both Langmuir and Freundlich models, with maximum adsorption capacities of 97.69, 94.86, and 93.67 mg g⁻¹ for PS, PP, and PE, respectively. The nanocomposite retained high recyclability, maintaining 95–97 ± 3.1% removal after five adsorption–desorption cycles. These findings demonstrate that ZIF-67/g-C₃N₄/CS is a durable and high-performance adsorbent for microplastic remediation, with strong potential for application in municipal wastewater treatment, constructed wetlands, and advanced water-polishing systems. Full article

Coastal riparian zones are important transitional areas for carbon cycling between terrestrial and aquatic ecosystems. However, the associations among litter-derived dissolved organic matter (DOM), soil DOM composition, and soil organic carbon (SOC) fractions across habitats remain insufficiently understood. This study aimed to clarify SOC fraction distribution in woody and herbaceous habitats and evaluate its associations with litter-derived DOM, soil DOM composition, and soil environmental factors in different seasons from a coastal riparian zone. In this study, woody habitats had higher SOC content in March, whereas herbaceous habitats showed greater SOC content in November. Particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) were generally higher in different habitats. MAOC accounted for a large proportion of the measured SOC-related pools and showed a consistent positive association with SOC content. Soil DOM consisted of protein-like and humic-like components, with herbaceous habitats showing a stronger protein-like component and woody habitats showing a stronger humic-like component in March. Woody litter showed greater DOC and DON release potential than herbaceous litter leachates, while litter-derived humic-like DOM was closely associated with a soil humic-like component. The labile SOC pool was mainly associated with vegetation type and electrical conductivity, whereas MAOC was positively associated with soil moisture content and total phosphorus. Overall, the distribution of SOC fractions in coastal riparian habitats is shaped by habitat-specific environmental factors, including vegetative carbon inputs, litter leaching and soil physicochemical properties. This finding is critical for developing targeted management strategies to facilitate SOC accumulation in coastal zones. Full article

Mineralization of soil organic carbon (SOC) is an important component of the soil carbon cycle. Studies have shown that rice–fish cocultures increased SOC; however, the question of whether raising aquatic animals with rice affects SOC mineralization remains unresolved. In this study, we conducted a field experiment to test SOC mineralization under three types of rice–aquatic animal cocultures (i.e., rice–fish coculture, RF; rice–crayfish coculture, RC; and rice–turtle coculture, RT) and rice monoculture (RM). SOC fractions, soil aggregate structure and SOC mineralization were determined in the experiment. Total SOC and microbial biomass carbon (MBC) under RT were significantly higher than under other treatments, and no significant differences in other SOC fractions were found among the treatments. For soil aggregates, there were significant differences in the proportions of large macroaggregates (LMA), microaggregates (MiA), and mean weight diameter (MWD) among the treatments. The LMA proportion significantly reduced while the MiA increased under the RT treatment compared to other treatments. SOC mineralization rates significantly differed among the treatments, where the RT and RC treatments had significantly higher mineralization ratios and daily average mineralization rates than the RF and RM treatments. RDA indicated that SOC fractions and soil aggregate structure influenced SOC mineralization. Our results demonstrate that aquatic animals exert differential effects on SOC mineralization, primarily through altering soil aggregate structure and SOC fractions. These findings highlight that the effects of aquatic animals on SOC dynamics should be considered in the assessment of coculture outcomes. Full article

As the primary component of harmful algal blooms, cyanobacteria exhibit unique adaptation strategies under environmental stress. The impact of erythromycin (ETM), a common macrolide antibiotic in aquatic environments, on colonial cyanobacteria remains unclear. This study examined the chronic toxic effects of different ETM concentrations (0.01, 0.1, 1, 10, 20 and 100 μg/L) on colonial Microcystis aeruginosa (M. aeruginosa) under varying nutrient conditions. Results showed that at 0.01–1 μg/L, ETM could promote the growth of M. aeruginosa, while high concentrations of ETM (≥10 μg/L) significantly inhibited growth (p < 0.05). Low-level ETM exposure accelerates M. aeruginosa growth by boosting PSII efficiency, extracellular polymeric substance (EPS) production, and the activities of superoxide dismutase (SOD) and catalase (CAT). Metatranscriptomic and metabolomic analyses further reveal that this stimulation is underpinned by enhanced trace-element uptake, reinforced carbon cycling, and increased biosynthesis of proteins, polysaccharides, and chlorophyll precursors. High-level ETM exposure inhibited the growth of M. aeruginosa, as evidenced by decreased photosynthesis, damaged membranes and suppressed metabolic activity. Metatranscriptomic and metabolomic analyses showed the upregulation of photosynthesis andpathways, metabolic pathways, and the accumulation of potent allelochemicals in P-limited cells exposed to 10 µg/L ETM relative to 10 µg/L ETM in nutrient-replete BG11 medium. Furthermore, phosphorus deficiency may enhance the potential of net methane formation. These findings underscore the complex interactions between antibiotic exposure and nutrient stress in cyanobacteria, with significant implications for environmental management of antibiotic contamination. Full article

Per- and polyfluoroalkyl substances (PFAS) such as perfluorooctanoic acid (PFOA) persist in aquatic environments due to their extremely strong C–F bonds and high environmental stability/poor biodegradability, creating an urgent demand for high-performance and scalable adsorption treatment technologies. This study reports the synthesis, characterization, and fixed-bed column adsorption performance of a dual-polymer-modified activated carbon adsorbent engineered for enhanced PFAS capture. Activated carbon (AC) was sequentially functionalized with polyethyleneimine (PEI) and poly(chlorotrifluoroethylene–co-vinylidene fluoride) (Kel–F) to form the fluorine-rich, amine-grafted composites AC–PEI–KelF and AC–PEI–KelF–PEI. Surface-area studies of the modified AC adsorbents showed a reduction in surface area of about a factor of two, possibly due to pore blockage by the polymers. Continuous-flow column breakthrough studies demonstrated dramatic improvements in perfluorooctanoic acid (PFOA) removal efficiency, with 50% maximum breakthrough time increasing from 80 min for AC to 540 min for AC–PEI–KelF and 1500 min for the AC–PEI–KelF–PEI formulation. Thomas model adsorption capacities for AC, AC–PEI–KelF and AC–PEI–KelF–PEI were, respectively, 65, 490, and 1130 mg/g. The adsorption mechanism, using selective mobile phases, was shown to be due to a combination of electrostatic and hydrophobic/fluorophilic interactions. Kinetic analysis showed that adsorption exhibited pseudo-second-order behavior, with multi-stage intraparticle diffusion. The optimized composite also exhibited strong regeneration stability, retaining 79% performance after six adsorption–desorption cycles, and displayed high selectivity for PFOA, even in the presence of structurally related competitors such as octanoic acid. The adsorption of perfluoropentanoic acid and undecafluoro-2-methyl-3-oxahexanoic acid (GenX) was also significant, and some interaction with trifluoroacetic acid was noted. Full article

Global wastewater generated in unprecedented volumes places a significant strain on aquatic environments, challenging the municipal sector to transition from energy-heavy pollutant removal technologies towards alternative resource recovery strategies with a low carbon footprint. The aim of this work is to review microalgae-based phycoremediation as a sustainable, cost-effective alternative that extracts nutrients from municipal, agricultural, and industrial streams without generating secondary chemical pollution. By utilizing these nutrient-rich effluents, microalgal cultivation generates valuable biomass for downstream valorization into biofuels, biofertilizers, biostimulants, and high-value biopolymers, while eliminating or reducing the costs of synthetic cultivation mediums. However, integrated techno-economic analyses (TEA) and life cycle assessments (LCA) reveal critical socio-technical bottlenecks. Full article

The contamination of aquatic ecosystems by synthetic dyes such as Safranin O poses significant environmental and health risks. This study reports the synthesis of TiO₂-ZnO heterostructures via a Ruta graveolens-mediated sol–gel method, where the plant extract acts as a structure-directing agent and precursor for residual carbon species. The resulting bio-hybrid catalyst achieved a degradation efficiency of 94% ± 2% under simulated solar irradiation, outperforming UV light (78% ± 3%) and visible light alone (81.18%). The optimal catalyst loading was determined to be 1.0 g L⁻¹, with maximum performance observed at near-neutral pH (6–7). Optical characterization revealed a direct bandgap of 2.69 eV, representing a significant red-shift from pristine TiO₂ and ZnO. The catalyst maintained 90% of its initial degradation efficiency after five consecutive regeneration cycles, demonstrating excellent reusability. Kinetic analysis confirmed pseudo-first-order behavior, while radical scavenging experiments identified superoxide radicals (•O₂⁻) as the dominant reactive species. This work establishes that plant-derived carbon precursors can effectively modify the electronic properties of TiO₂-ZnO heterojunctions, offering a sustainable approach for photocatalytic water remediation. Full article

Lead (Pb²⁺) and cadmium (Cd²⁺) are among the most hazardous heavy metal pollutants in wastewater owing to their high toxicity, environmental persistence, and detrimental impacts on human health and aquatic ecosystems. In this study, a novel ternary magnetic composite, SnFe₂O₄/activated carbon/polypyrrole (SnFe₂O₄/AC/PPy), was effectively synthesized and tested as an effective adsorbent in the removal of Pb²⁺ and Cd²⁺ from aqueous water. The composite was prepared by depositing spinel SnFe₂O₄ nanoparticles on activated carbon, followed by in situ polymerization of polypyrrole to enhance surface functionality and adsorption affinity. The successful fabrication of the porous SnFe₂O₄/AC/PPy hybrid composite was confirmed through FTIR, XRD, SEM–EDS, BET, XPS, and VSM characterization. The composite demonstrated a relatively high surface area (352.3 m²/g) and adequate magnetic responsiveness (12.33 emu/g), ensuring facile magnetic separation following wastewater treatment. Batch adsorption experiments showed great removal efficiency of 95.02 and 92.48% for Pb²⁺ and Cd²⁺ ions, respectively, at optimum conditions. The adsorption equilibrium data followed the Langmuir isotherm model with maximum adsorption capacities of 187.07 mg/g for Pb²⁺ and 96.45 mg/g for Cd²⁺ ions, which were attributed to monolayer adsorption on homogenous active sites. The kinetic and isothermal model indicated that the adsorption process was controlled by the combination of physical and chemical interactions. Thermodynamic parameters showed negative Gibbs free energy and enthalpy changes (ΔH° = −49.74 kJ/mol for Pb²⁺ and −38.82 kJ/mol for Cd²⁺ ions), confirming the spontaneous and exothermic nature of adsorption. Furthermore, the increasingly negative ΔG° values at lower temperatures indicated that the adsorption was thermodynamically more favorable under cooler conditions. According to the regeneration studies, the composite maintained a high removal efficiency after five consecutive cycles. In general, SnFe₂O₄/AC/PPy composite has good potential as a stable, reusable, and high-performance adsorbent to treat heavy metal wastewater. Full article

An emerging environmental pollutant, microplastics have garnered global attention due to their widespread presence in soil and aquatic ecosystems. Early research primarily treated microplastics as single pollutants, focusing on their individual toxic effects. However, microplastics in the environment exist as a complex mixture, comprising various polymer types, sizes, shapes, and aging states. This diversity influences how microplastics regulate ecosystem carbon and nitrogen cycles and intervene through pathways such as direct carbon input, physical disturbance, microbial community restructuring, and coupled effects. This paper systematically reviews the characteristics of microplastic diversity and its mechanisms influencing carbon and nitrogen cycles: the chemical structure of polymers determines bioavailability and degradation rate, with biodegradable plastics altering carbon and nitrogen transformations more significantly than conventional plastics; microplastics of different sizes affect nitrogen transformation dynamics by modulating specific surface area and microbial colonization, with small-sized biodegradable microplastics particularly inhibiting plant nitrogen uptake; aging modifies surface properties and dissolved organic carbon release, thereby enhancing their role in promoting greenhouse gas emissions. Existing studies are largely confined to short-term laboratory simulations, leaving a gap in understanding the comprehensive effects of microplastic diversity under long-term, field conditions. Future research should focus on standardized methods and long-term experiments with multi-factor coupling to provide a scientific basis for ecological risk assessment of microplastic pollution. Full article

Engineered nanomaterials are widely used in environmental remediation, agriculture, and industrial applications owing to their large specific surface area, high reactivity, and tunable physicochemical properties. However, their release into aquatic environments has raised increasing concerns regarding potential risks to primary producers. Microalgae are highly sensitive to environmental stressors and play essential roles in photosynthesis, nutrient cycling, carbon fixation, and aquatic food-web stability, making them important model organisms for assessing the toxicity of engineered nanomaterials. This review summarizes the toxic effects and mechanisms of representative engineered nanomaterials, including metal and metal oxide nanoparticles, nanoplastics, and carbon-based nanomaterials, on microalgae. Major toxic pathways include nanoparticle attachment and aggregation on algal surfaces, shading effects, membrane damage, altered permeability, cellular internalization, toxic ion release, reactive oxygen species overproduction, photosynthetic inhibition, and metabolic disturbance. The review further discusses how particle size, morphology, surface coating, dissolution, aging, light, pH, and natural organic matter regulate nanomaterial bioavailability and toxicity. Combined toxicity caused by coexisting nanoparticles or emerging pollutants is also considered, with emphasis on synergistic, antagonistic, and concentration-dependent effects. Finally, recent methodological advances, such as near-native imaging, Raman-based spectroscopy, particle-specific elemental analysis, and multi-omics approaches, are highlighted. This review provides an integrated perspective for understanding nanomaterial toxicity to microalgae and supports future ecological risk assessment in aquatic environments. Full article