Search Results (1,503)

Over the past decade, microplastic pollution has emerged as a subject of considerable interest and extensive research, with implications for human health and ecosystems. This paper briefly summarized the sources of microplastics and their distribution in the soil. It comprehensively addressed the effects of microplastics on the soil–plant system, including the impacts on soil physicochemical properties and plant rhizosphere microbial communities. The effects of microplastics on plant growth, along with their transformation and accumulation within plants, were evaluated. Microplastics can adhere to soil particles and root surfaces and, under certain conditions, may associate with outer root tissues or enter plants through damaged or vulnerable sites. Their presence in the soil–plant system may interfere with water and nutrient uptake, affect photosynthesis, and induce cytotoxic or genotoxic responses. Furthermore, the co-occurrence of microplastics with toxic substances or soil remediation materials may exacerbate the adverse effects on plants and ecosystems. Future research should focus on the development of methods for detecting microplastics in soils and plants and investigate the interactions between microplastics and other environmental factors within the soil–plant system. Further investigation is required regarding the role of microplastics in hyperaccumulating plants, particularly concerning plant-based methods for removing heavy metal pollutants. This study establishes a scientific basis for understanding the effects of microplastics on soil–plant systems. Full article

River sediments act not only as important sinks for heavy metal pollution in watersheds, but also as potential secondary sources under changing environmental conditions. Heavy metals can enter river systems through industrial wastewater discharge, agricultural non-point runoff, urban stormwater and sewage inputs, mining and smelting activities, and atmospheric deposition. During adsorption onto suspended particles, sedimentation, and resuspension, metals such as Cd, Pb, Cr, Cu, Zn, Ni, As, and Hg progressively accumulate in sediments. Because heavy metals are persistent, non-degradable, and bioaccumulative, contaminated sediments can record historical watershed pollution while also releasing metals back into overlying water under hydrodynamic disturbance, pH and redox fluctuations, organic matter mineralization, benthic bioturbation, and dredging activities, thereby threatening aquatic ecosystem stability and human health. Using a global methodological framework with particular emphasis on Chinese river basins, this review systematically summarizes key issues in the study of heavy metal pollution in river sediments, including spatial–temporal distribution and operationally defined fractionation, pollution levels and ecological risk assessment, source apportionment, and remediation and management technologies. Current evidence indicates that heavy metal contamination in river sediments exhibits pronounced spatial heterogeneity and watershed-specific characteristics. Its distribution is jointly controlled by geological background, land use patterns, source input intensity, hydrodynamic conditions, sediment particle size composition, and organic matter content. Methodologically, the field has evolved from single total concentration monitoring and exceedance-based evaluation toward integrated assessment systems that combine total concentrations, operationally defined fractionation, bioavailability, ecological risk, health risk, and source contribution. The joint use of BCR sequential extraction, the geoaccumulation index (Igeo), the pollution load index (PLI), the potential ecological risk index (RI), the risk assessment code (RAC), sediment quality guidelines (SQGs), receptor models, isotope tracing, and machine learning has substantially improved pollution identification, risk zoning, and source apportionment. Overall, research on heavy metal pollution in river sediments has shifted from descriptive judgments of whether contamination exists toward mechanistic and management-oriented questions concerning pollution sources, risk evolution, and remediation strategies. However, important gaps remain in compound pollution transformation mechanisms, regional background values and evaluation benchmarks, uncertainty in model parameters, long-term dynamic monitoring, and engineering-scale verification of remediation technologies. Future studies should strengthen multi-media, multi-scale, and long-term monitoring and further integrate fractionation analysis, toxicological effects, source apportionment models, and remediation technologies to provide a scientific basis for watershed ecological security and precision management of contaminated sediments. 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

Ultraviolet (UV) radiation was selected in this study to evaluate its assistant remediation effects on Cr-contaminated soil. Various remediation materials, including corn stover (CS), corn stover biochar (CSB), polypyrrole-modified 44 corn stover (PPy-CS), and polypyrrole-modified corn stover biochar (PPy-CSB), were employed to evaluate their synergistic effects with UV radiation. The results showed that UV radiation increased the toxicity characteristic leaching procedure (TCLP) Cr(VI) when no other remediation was added to the contaminated soil. However, when the remediation materials were added, with UV radiation, the contents of TCLP-Cr(VI) decreased, while the contents of Cr(III) increased, and the removal rates of TCLP-Cr(VI) in contaminated soil treated by CSB, PPy-CSB, CS, and PPy-CS were 18.7%, 7.6%, 11.0%, and 8.2% higher than those of the non-irradiated groups, respectively. Notably, the CS group demonstrated superior efficacy in Cr(VI) removal compared with CSB under UV irradiation. Meanwhile, characteristic analysis including electron paramagnetic resonance (EPR), Fourier-transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS) assisted us in finding reaction mechanisms, which implied that UV irradiation could enhance the content of oxygen free radicals on the material surface and effectively activate the reactions between Cr(VI) and remediation materials. This study verified that UV irradiation could also be a promising tool in the remediation of heavy-metal-contaminated soil. Full article

Elevated atmospheric carbon dioxide (ECO₂) is a key climatic factor influencing the resilience of plant–microbial symbiotic systems against heavy metal contamination. Robinia pseudoacacia–rhizobia symbiosis shows great potential for cadmium (Cd) remediation. However, the mechanism by which ECO₂ regulates Cd phytostabilization in symbiosis remains unclear. This study conducted a 90-day experiment in growth chambers to investigate the effects of ECO₂ on the growth, Cd accumulation and chemical forms, as well as nutrient uptake and antioxidant system in Robinia pseudoacacia–rhizobia symbiosis. Results indicated that ECO₂ significantly increased plant biomass and photosynthetic efficiency while significantly raising Cd content in roots (34.5%, p < 0.001) and decreasing it in shoots (31.4%, p < 0.001). This resulted in a significant reduction in Cd translocation factor (TF). Meanwhile, ECO₂ markedly increased Cd accumulation in roots (81.2%, p < 0.001) and reduced the bioavailability of Cd in the symbiosis. Moreover, ECO₂ promoted the content of nutrients and stimulated the antioxidant system. The random forest model indicated that root weight, Cd and Mn contents are the core factors for ECO₂-driven Cd phytostabilization. This study demonstrates that ECO₂ enhanced Cd phytostabilization by optimizing the resistance of symbiosis to Cd, offering a novel perspective for predicting plant–microbe joint restoration of heavy metal pollution under global climate change scenarios. Full article

Sudden tailings dam breaches trigger large-scale heavy metal compound pollution in coupled surface water–groundwater systems, requiring systematic full-cycle ecological damage quantification tools applicable to diverse contamination types. This study constructs an integrated full-cycle ecological damage assessment framework for sudden water pollution accidents, integrating three core modules: multi-model pollutant migration prediction, multi-scale aquatic biological damage diagnosis, and three-dimensional ecological-economic loss accounting. The framework adopts a modular design that can potentially accommodate heavy metals (Cd, Cr, As, Pb) and organic pollutants such as polycyclic aromatic hydrocarbons (PAHs), with standardized molecular, individual, and population-level biological endpoints and corresponding pollutant dose–response templates reserved as reference calculation modules. However, applicability beyond this case has not been validated and requires case-specific calibration. To verify the operability and accuracy of the proposed integrated system, a typical tailings dam leakage incident dominated by hexavalent chromium (Cr(VI)) and arsenic (As) pollution was selected as the practical validation case; all field monitoring, pollutant simulation, and final economic loss quantification in this case exclusively rely on on-site measured Cr(VI) and As data, while Cd and PAH-related biological response curves and remediation cost formulas retained in the manuscript only serve as illustrative universal template components of the framework rather than case-measured results. For the Cr(VI)/As pollution case, the advection–diffusion model simulation revealed that the Cr(VI) contamination plume horizontally spread 250 m within 48 h and extended to 560 m after seven days, and anaerobic groundwater environments drove the transformation of toxic mobile trivalent arsenic (As(III)) from primary pentavalent arsenic. The calibrated SWAT model achieved Nash–Sutcliffe efficiency (NSE) coefficients of 0.75 for dissolved Cr(VI) and 0.68 for particulate As. The graph theory-based rapid prediction model cut computation duration down to minutes; when validated against independent field monitoring data, it yielded an average relative error of 14.2%, and its consistency with the SWAT model reached 10.5% relative deviation, satisfying the accuracy requirement for emergency early warning. Field biological monitoring demonstrated substantial ecological impairment: metallothionein (MT) expression in fish tissues was markedly elevated (the reported 6.2-fold induction value derives from standard Cd exposure template tests within the framework, with analogous MT upregulation also observed for field Cr(VI)/As co-stress), and benthic community Shannon diversity declined by over 50% in polluted river reaches. The standardized Ecological Damage Index (EDI) of the case was calculated as 480.2, indicating severe aquatic ecosystem damage, with total comprehensive ecological and economic losses reaching 17.25 million CNY. This study innovatively couples high-precision physical transport models with fast emergency prediction algorithms and establishes a complete multi-tier biological indicator chain linking molecular biomarkers to community integrity metrics; the three-dimensional loss accounting system integrating ecosystem service impairment, restoration expenditure, and post-pollution recovery loss realizes closed-loop full-cycle damage evaluation. The proposed framework, demonstrated for Cr(VI) and As pollution, has a modular design that may potentially be extended to other pollutants such as Cd and PAHs by adjusting model parameters, providing a quantitative reference for emergency disposal, pollution remediation, and ecological compensation of water contamination accidents, although further validation across different pollutants and hydrological settings is required. Full article

Anthropogenic pollution of aquatic ecosystems presents a significant global challenge, underscoring the urgent need for resilient, biologically mediated remediation strategies. In this context, microalgae have emerged as a compelling solution, owing to their inherent adaptability to diverse environments and their capacity for efficient contaminant mitigation through bioremediation. These organisms possess the potential to sequester and remove a broad spectrum of pollutants from wastewater streams, including excess nutrients, organic substrates, heavy metals, and various emerging contaminants. Specifically, their metabolic versatility allows these microorganisms to tolerate and degrade complex substances such as recalcitrant micropollutants and hydrocarbons even under fluctuating environmental conditions. This review evaluates extremophilic microalgae as specialized biological agents capable of functioning under harsh anthropogenic stressors that may constrain the performance of microalgal strains commonly investigated for wastewater treatment. Their distinctive stress tolerance may provide advantages for treating wastewater characterized by extreme physicochemical conditions. By examining the unique metabolic pathways of these extremophiles, this analysis addresses critical gaps in the current bioremediation literature regarding the practical scalability and economic viability of integrating such specialized biomass into large-scale treatment infrastructure. Full article

Conventional heavy metal remediation technologies are constrained by low efficiency, secondary pollution risks, and limited scalability. Dissolved organic matter (DOM), with its green, cost-effective complexation properties, has become a promising pathway for pollution control. Existing patent bibliometric studies in this field suffer from single-database bias, limited causal quantification of policy impacts, and incomplete depiction of global–local technological heterogeneity. To address these gaps, this study maps the technological innovation landscape of DOM interactions with four typical heavy metals (Cd, Pb, Cu, Zn) during 2004–2024, using a complementary dual-database framework combining Derwent and IncoPat. We integrate a three-dimensional “time–region–technology” analytical framework with interrupted time series analysis (ITSA), after standardized data processing including family deduplication and citation normalization. Cross-validation confirms that China contributes the largest share of global patent output (46.6% in Derwent, 55.0% in IncoPat). Three milestone environmental policies in China exert sequentially intensifying causal effects on patent growth (all p < 0.05), forming a closed-loop mechanism of policy orientation, funding support, technology transfer, and international diffusion. We identify a pronounced global–local technological divergence: global frontier innovation centers on digital basic research, whereas local innovation in China prioritizes engineering applications. Core patents advance the field through cross-domain technology adaptation, and the representative technical paradigm (exemplified by patent CN101168852A) has been industrially validated. These findings provide empirical support for engineering translation and policy optimization in DOM-based heavy metal remediation. Full article

The complex composition of landfill leachate, characterized by high concentrations of refractory organic matter, ammonium nitrogen, and heavy metals, requires efficient and sustainable treatment technologies. Recently, sludge-based adsorbents (SBAs) obtained from wastewater treatment plants (WWTPs) sludge have emerged as promising alternatives to the conventional activated carbon materials for landfill leachate. This review critically evaluates the recent literature related to the transformation of sludge waste and municipal solid waste-based adsorbents into high-efficiency SBAs as a circular economy strategy for leachate remediation. The correlation of the physicochemical characteristics of landfill leachate with the properties of SBAs to enhance the removal of specific contaminants is discussed. The treatment strategies for landfill leachate including physicochemical, biological, and integration of those are summarized. By correlating adsorption performance with SBAs’s properties and circular economy principles, this review identifies the key knowledge gaps and provides guidance for the development and large-scale implementation of sustainable leachate treatment technologies. Furthermore, the prospects for the application of SBAs in the closed-loop landfill leachate treatment system are addressed. Full article

Biochar is a porous carbonaceous material synthesized through the pyrolysis of diverse biomass resources, including agricultural and forestry residues as well as livestock manure. It possesses superior characteristics such as a large specific surface area, adjustable pore architecture, abundant surface functional groups, and favorable electrical conductivity. With the increasingly severe global energy shortage and environmental pollution problems in recent years, biochar has emerged as a green, low-cost functional material with distinct application superiority in multiple key research directions, including energy storage and conversion, chemical catalysis, environmental restoration, and signal sensing and detection. This study comprehensively summarizes the latest research advances of biochar in the aforementioned application fields, focusing on innovative achievements in photocatalytic and electrocatalytic hydrogen generation, supercapacitors and electrochemical energy storage systems, persulfate activation technology, carbon dioxide capture, remediation of heavy metal and organic contaminants, volatile organic compound (VOC) adsorption, as well as electrochemical sensing devices. Existing research results demonstrate that modification strategies including metal and non-metal doping, surface oxidation treatment, and compounding with semiconductors or metal oxide materials can effectively improve the catalytic activity and functional performance of biochar. Furthermore, this paper prospects the future interdisciplinary development trends of biochar, analyzes the existing research gaps in mechanism exploration, structural optimization design, and industrial large-scale preparation, and provides theoretical and practical references for the further popularization and application of biochar in sustainable energy development and environmental governance fields. Full article

Copper and lead contamination in loess areas poses a potential threat to soil environmental quality and sustainable land use, while the low permeability, high clay content, and strong buffering capacity of loess often limit the efficiency of conventional electrokinetic (EK) remediation. This study developed an enhanced EK system integrating novel hydrogel (NH) electrodes, a poly(diallyldimethylammonium chloride)-modified activated carbon/carbon fibre (MAC/CF) permeable reactive barrier (PRB), and a vertical voltage for the remediation of Cu- and Pb-contaminated loess. The effects of vertical voltage (0, 10, 20, 30, and 40 V) on EK behaviour, contaminant migration, and removal performance were investigated. The results showed that the MAC/CF PRB improved electrical stability, enhanced electroosmotic transport, and regulated pH evolution by providing conductive pathways and reactive sites for OH⁻ capture and metal adsorption. Compared with the system without a PRB, the accumulated electroosmotic flow (EOF) increased from approximately 680 to 980 mL. The vertical voltage further promoted Cu²⁺ and Pb²⁺ redistribution into the PRB and enhanced the migration–adsorption coupling process. The optimal voltage of 30 V achieved the best remediation performance, with Cu and Pb removal efficiencies of 69–80% and 32–36%, respectively, within 72 h at initial concentrations of 500 mg kg⁻¹. Mechanistic analysis revealed that the vertical voltage transformed the MAC/CF barrier from a passive adsorption layer into an electrically activated migration–capture interface. The synergistic effects of ion transport regulation, OH⁻ buffering, conductive network construction, and heavy metal adsorption effectively suppressed precipitation-induced focusing and improved remediation efficiency. This study provides a promising strategy for enhancing EK remediation of low-permeability and structurally sensitive soils. 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

Heavy metal contamination in agricultural soils threatens food security and ecosystem sustainability worldwide. Microbial inoculants have been widely used to alleviate heavy metal phytotoxicity, yet the factors determining their efficacy remain unclear. Here, we conducted a global meta-analysis of 774 paired observations from 70 studies to evaluate the effects of microbial inoculation on plant performance under heavy metal stress. Overall, microbial inoculation significantly increased plant biomass, with greater benefits under higher levels of metal stress. Combined bacterial and fungal inoculation consistently outperformed single inoculations, while non-mycorrhizal beneficial fungi produced the strongest positive effects among individual inoculants. Soil organic carbon and sand content were positively associated with inoculation efficacy, whereas mean annual temperature was negatively associated with inoculation efficacy. Our results demonstrate that microbial inoculation is an effective strategy for enhancing plant tolerance to heavy metal stress and that its efficacy is strongly influenced by inoculation strategy and soil properties. These findings provide a quantitative basis for optimizing microbial-assisted remediation and developing context-specific management strategies for contaminated agricultural soils. Full article

Modified biochar has become an efficient tool for modulating availability of heavy metals in soils. To identify a preferable material and explore the remediation mechanism of modified biochar for Pb-contaminated soil, H₂O₂-, HNO₃-, KMnO₄-, and CaCl₂-modified biochars were applied at three ratios (1%, 2% and 3% w/w) to immobilize Pb in alkaline soil from coal-based solid waste dumps. Results showed that HNO₃-BC exhibited abundant acidic functional groups, and KMnO₄-BC had increased pH and CEC content. The application of modified biochars significantly altered soil Pb fractions. Compared with biochar and the control, the application of HNO₃-BC and KMnO₄-BC decreased acid-extractable Pb and increased the residual Pb fraction in soil. HNO₃-BC was more effective than KMnO₄-BC in promoting Pb transformation from labile fraction into stable fraction. The content of soil available Pb significantly decreased with increasing application ratio of HNO₃-BC. The complexation between soil Pb and acidic functional groups on the biochar surface is considered the primary mechanism for reducing Pb mobility and availability in contaminated soils. This research demonstrated that HNO₃-BC can serve as a potentially effective amendment for the remediation of heavy metal-contaminated alkaline soils in northern China. Full article

Heavy metal pollution in water bodies is a serious environmental and public health concern, as these contaminants are toxic, persistent and bioaccumulative in ecosystems and human tissues. Conventional remediation technologies are expensive, require constant monitoring and do not fully remove them. Recent studies have shown the potential, sustainability and cost-effectiveness of biosorption using algal biomass. This review gives a detailed assessment of the potential of algae and cyanobacteria as cheap biosorbents for the removal of heavy metals from wastewater. The sorption efficiency of algae and cyanobacteria is critically evaluated in terms of important operating parameters such as pH, temperature, initial metal concentrations, biomass loading and contact time. The diversity of metal-binding functional groups such as carboxylate, amine, imidazole, phosphate, sulfhydryl, sulfate and hydroxyl groups present on the surface of algal cells is discussed in detail, highlighting the complex algal biochemistry. Recent developments in functionalized algal materials are also discussed, with emphasis on their potential to improve adsorption capacity, selectivity, regeneration, and practical applicability. However, this review also identifies some limitations such as energy requirements for the drying of biomass, limitations of batch systems for microalgae applications, and challenges for large-scale implementation. Future research directions are suggested to highlight the urgent need for functionalized algal materials, optimization of large-scale applications, and integration of biosorption with other treatment technologies in the framework of a circular economy. Full article