Search Results (132)

Conventional descriptive statistical approaches in per- and polyfluoroalkyl substance (PFAS) environmental forensics often fail under small-sample, ecosystem-level complexity, challenging the optimization of sampling, monitoring, and remediation strategies. This study presents an advance from passive description to adaptive decision-support for complex PFAS contamination. By integrating Bayesian optimization (BO) via Gaussian Processes (GP) with a Generalized Linear Mixed Model (GLMM), we developed a signal-extraction framework for both understanding and action from limited data (n = 18). The BO/GP model achieved strong predictive performance (GP leave-one-out R² = 0.807), while the GLMM confirmed significant overdispersion (1.62), indicating a patchy contamination distribution. The integrated analysis suggested a dominant spatiotemporal interaction: a transient, high-intensity perfluorooctane sulfonate (PFOS) plume that peaked at a precise location during early November (the autumn recharge period). Concurrently, the GLMM identified significant intra-sample variance (p = 0.0186), suggesting likely particulate-bound (colloid/sediment) transport, and detected n-ethyl perfluorooctane sulfonamidoacetic acid (NEtFOSAA) as a critical precursor (p < 0.0001), thus providing evidence consistent with the source as historic 3M aqueous film-forming foam. This coupled approach creates a dynamic, iterative decision-support system where signal-based diagnosis informs adaptive optimization, enabling mission-specific actions from targeted remediation to monitoring design. Full article

Cadmium (Cd) contamination in agricultural systems poses significant ecotoxicological risks through bioaccumulation in food chains. While lime-based amendments are widely applied for Cd immobilization, mechanistic understanding of bioavailability control pathways remains limited. This study employed a meta-analysis methodology based on 260 datasets from 55 publications to systematically investigate the mechanisms and differences in the effectiveness of calcium hydroxide, calcium carbonate, and calcium oxide in regulating Cd migration in acidic soil–plant systems. The study revealed that lime-based materials synergistically regulated Cd migration through two processes: chemical fixation and ionic competition. Results showed lime application reduced soil available Cd by 33.0%, decreased grain Cd by 44.8%, increased soil pH by 15.6%, and enhanced exchangeable Ca by 35.2%. Chemical fixation was evidenced by Cd transformation from labile to stable forms (residual Cd: +29.5%, acid-soluble Cd: −17.5%). Ionic competition was quantitatively confirmed through strong negative correlation between exchangeable Ca and grain Cd (R² = 0.704). Among the materials, Ca(OH)₂ exhibits the highest efficiency in rapid pedogenic passivation (58.7% reduction in available Cd), whereas CaCO₃ demonstrates superior long-term grain Cd attenuation (65.7% inhibition) via sustained Ca²⁺ release and rhizosphere-regulated dissolution. This study advances mechanistic understanding of Cd bioavailability control and establishes quantitative frameworks for predicting ecotoxicological outcomes, providing scientific basis for optimizing remediation strategies to minimize Cd transfer through agricultural food chains. Full article

Red mud is a highly alkaline solid waste with an annual emission of over 200 million tons, which requires large-scale utilization methods. Soil Cd remediation is a global concern, due to its high toxicity and strong mobility. Given red mud’s potential for soil Cd remediation, this study reviews its basic characteristics, the mechanisms of soil Cd immobilization by red mud, and the use of red mud-based passivators for agricultural soil Cd remediation. In general, red mud regulates soil pH, thus increasing the soil’s Cd adsorption capacity; provides abundant surface active sites for adsorption and complexation with soil Cd; introduces cations to immobilize Cd via ion exchange; and enriches Cd-resistant microbe species to reduce soil Cd toxicity. Furthermore, the potential environmental risks and suggestions on red mud application are discussed. Further research should focus on improving the remediation effectiveness of red mud on cadmium-contaminated agricultural soil, demonstrating its long-term efficacy and economic costs, and proposing practical technical models and standards for application. Full article

This study innovatively combines the cyclic catalytic pyrolysis system (CCPS) with a circular pipe device, using biochar from potato peels (PP) and pig manure (PM) to passivate Cd and Pb in the soil, and explores the influencing mechanisms via multiple methods. Results showed that in aqueous adsorption, biochar from the CCPS performed better, with the potato peel-based biochar produced via the cyclic catalytic pyrolysis system (PPB-2) achieving 100% removal of Cd²⁺ and Pb²⁺ within 100–270 min. In the soil remediation experiment using a ring pipe setup, pig manure-based biochar produced via the cyclic catalytic pyrolysis system (PMB-2) exhibited superior performance, reducing Cd concentration from 22.36 mg/kg to 11.21 mg/kg (49.87% removal) and Pb concentration from 718.28 mg/kg to 400.09 mg/kg (44.3% removal) after 40 days. This confirms that the PM-derived biochar prepared by CCPS is more suitable for the remediation of cadmium- and lead-contaminated soils, providing a reference for research on soil heavy metal passivation. Notably, the raw materials (PP and PM) are low-cost, locally abundant agricultural wastes, enabling resource recycling and lowering large-scale application costs. The ring pipe encapsulation further simplifies operational procedures for practical promotion while avoiding direct biochar–soil contact and mitigating secondary pollution risks. Full article

The research on cadmium (Cd) pollution remediation technologies in farmland is of great significance for ensuring food security. However, there is currently a lack of empirical research on the passivation effects of the related repair materials on alkaline farmland in arid regions. This study selected a typical experimental area in a dryland corn farmland in Ningxia, Northwest China. Field experiments were conducted on four typical remediation materials: mercapto clay minerals, sepiolite remediation materials, microbial inoculants, and bio-organic fertilizers. The effects of these four materials on the available cadmium in the soil, cadmium content in corn stems and leaves, and enrichment coefficients were analyzed. The results show that the four types of remediation fertilizers have significant differences in their effects on the available Cd content in the soil, with a reduction range of 3.33–60.94%. The order of the inhibitory effect from strong to weak is as follows: mercapto clay mineral passivation material, bio-organic fertilizer, sepiolite, and microbial inoculant. The cumulative distribution pattern of Cd in the organs of corn plants is leaf > stem > grain. It reduces the cadmium content in corn stems by 7.01–37.16% and reduces the cadmium content in corn leaves by 1.45–26.56%. Under the four types of remediation fertilizer treatments, the enrichment coefficients of corn stems and leaves all decreased. The enrichment coefficient of stems decreased by 3.78% to 29.42%, and the enrichment coefficient of leaves decreased by 3.41% to 31.92%. The mercapto clay minerals passivation material has the best effect on reducing the available cadmium in the soil of dryland corn in the arid areas of Northwest China and also has the best effect on inhibiting the absorption of cadmium by various organs of corn. It can be further verified in the field and promoted for application, providing support for the restoration of heavy metal pollution in farmland based on local conditions and differentiated measures. Full article

Air pollution, soil contamination, and rising illness demand integrated, nature-based solutions. Willow trees (Salix spp.) uniquely combine ecological resilience with therapeutic value, remediating polluted environments while supporting human well-being. This review synthesizes recent literature on the established role of Salix spp. in phytoremediation and growing contribution to forest therapy through emissions of biogenic volatile organic compounds (BVOCs). As urbanization accelerates and environmental pressures intensify globally, the surprising adaptability and multifunctionality of Salix justify the utilization of this genus in building resilient and health-promoting ecosystems. The major points discussed in this work include willow-based phytoremediation strategies, such as rhizodegradation, phytoextraction, and phytostabilization, contributing to restoring even heavily polluted soils, especially when combined with specific strategies of microbial augmentation and trait-based selection. Salix plantations and even individual willow trees may contribute to forest therapy (and ‘forest bathing’ approaches) through volatile compounds emitted by Salix spp. such as ocimene, β-caryophyllene, and others, which exhibit neuroprotective (against Parkinson’s disease), anti-inflammatory, and mood-enhancing properties. Willow’s significantly extended foliage season in temperate regions allows for prolonged ‘forest bathing’ opportunities, enhancing passive therapeutic engagement in urban green infrastructures. Remarkably, the pharmacological potential of willow extends beyond salicin, encompassing a diverse array of phytocompounds with applications in phytomedicine. Finally, willow’s ease of propagation and adaptability make this species a convenient solution for multifunctional landscape design, where ecological restoration and human well-being converge. Overall, this review demonstrates the integrative value of Salix spp. as a keystone genus in sustainable landscape planning, combining remarkable environmental resilience with therapeutic benefits. Future studies should explore standardized methods to evaluate the combined ecological and therapeutic performance of Salix spp., integrating long-term field monitoring with analyses of BVOC emissions under varying environmental stresses. Full article

Mineral resource exploitation poses substantial pressure on regional ecological environments. The Xiaoxing’anling mineral belt—a critical ecological functional area and a major mineral-rich zone in China—exemplifies such environmental vulnerability. Conducting a scientific assessment of ecological changes in mining-affected regions is essential for balancing resource development and environmental protection. Based on the DPSIR (Driver-Pressure-State-Impact-Response) model, this study developed a comprehensive indicator system tailored for evaluating ecological changes in mining areas. Using the Xiaoxing’anling mineral belt in Heilongjiang Province as a case study, we integrated remote sensing, geographic information, statistical yearbooks, and field survey data, and applied an objective weighting method to quantitatively assess ecological changes from 2010 to 2020. The results indicate the following: (1) Ecological evolution exhibits significant spatiotemporal heterogeneity, with persistently high ecological pressure in the eastern region leading to continued environmental degradation. (2) Socioeconomic transformation driven by new energy development has weakened the overall development driver, though Yichun City remains a core driver due to its super-large mineral deposits. (3) Ecological impacts demonstrate a spatial spillover effect, extending to urban residential areas, while ecological response measures lag severely and are misaligned with pressure distribution—nature reserves have become high-value response zones rather than the actual mining sites. (4) The comprehensive ecological restoration index is on a downward trend. The measures currently adopted by society to improve the ecology of mining areas, such as using greener mining methods and increasing vegetation coverage, are unable to counteract the adverse effects of previous mining activities. This study identifies passive and lagging responses as the key bottlenecks impeding ecological recovery. We emphasize that future management strategies must shift from passive remediation to proactive intervention, and propose clear spatial and institutional directions for sustainable governance in mining areas. Full article

Rice (Oryza sativa L.) exhibits a heightened ability to bioaccumulate arsenic (As) and cadmium (Cd), which directly affects the quality of agricultural products and poses serious risks to both the ecological environment and human health. Due to considerable differences in the occurrence states and chemical behaviors of As and Cd, simultaneous remediation efforts for water or soil contaminated by these elements often prove challenging. Our previous study indicated that the addition of both As and Cd markedly promoted the immobilization of each other by sulfidized nano-zero-valent iron (S-nZVI). To further explore the influence of S-nZVI on the passivation of As-Cd composite contamination, we examined its effect on the residual proportions of As and Cd in the soil by varying the dosage of S-nZVI, the soil moisture content and pH levels. At 2 g·kg⁻¹ S-nZVI over a 90-day period, residual fraction reached 83% for As and 39% for Cd. When the water content was 100%, residual fractions peaked at 83% for As and 29% for Cd. Additionally, variations in initial pH levels were found to have no significant impact on the remediation efficiency of As and Cd. This suggests that S-nZVI has the ability to sustain the stabilization of As and Cd in soil across diverse environmental conditions. The evident passivation effects on As-Cd composite contaminated soil can effectively reduce the potential ecological risk associated with these contaminants. Full article

Iron-based catalysts for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation represent a cornerstone of advanced oxidation processes (AOPs) in environmental remediation, prized for their cost-effectiveness, environmental compatibility, and high catalytic potential. These catalysts, including zero-valent iron, iron oxides, and iron-organic frameworks, activate PMS/PDS through heterogeneous and homogeneous pathways to generate reactive species such as sulfate radicals (SO₄•⁻) and hydroxyl radicals (•OH). However, their large-scale implementation is constrained by inefficient iron cycling, characterized by sluggish Fe³⁺/Fe²⁺ conversion and significant iron precipitation, leading to catalyst passivation and oxidant wastage. This comprehensive review systematically dissects innovative strategies to augment iron cycling efficiency, encompassing advanced material design through elemental doping, heterostructure construction, and defect engineering; system optimization via reductant incorporation, bimetallic synergy, and pH modulation; and external field assistance using light, electricity, or ultrasound. We present a mechanistic deep-dive into these approaches, emphasizing facilitated electron transfer, suppression of iron precipitation, and precise regulation of radical versus non-radical pathways. The performance in degrading persistent organic pollutants—including antibiotics, per- and polyfluoroalkyl substances (PFASs), and pesticides—in complex environmental matrices is critically evaluated. We further discuss practical challenges related to scalability, long-term stability, and secondary environmental risks. Finally, forward-looking directions are proposed, focusing on rational catalyst design, integration of sustainable processes, and scalable implementation, thereby providing a foundational framework for developing next-generation iron-persulfate catalytic systems. Full article

Solar photovoltaic systems now produce the lowest-cost electricity in history and coupling with agriculture in agrivoltaics increases crop yields. This indicates solar will continue to experience explosive growth. Concerns exist, however, about the long-term end-of-life decommissioning of solar farms. For example, due to fossil fuel decommissioning mismanagement, Alberta is inundated with orphaned oil and gas wells that have remediation cost estimates of CAD$100 billion. Such comparisons have prompted preemptive legislation targeting solar farms, but is the fear justified? This study addresses this question by (1) analyzing warranted and actual lifespans of key agrivoltaic system components, (2) experimentally measuring microclimate impacts of two agrivoltaic arrays (fully powered with electricity extraction and unpowered to simulate post-inverter-failure conditions) and (3) quantifying agrivoltaic yield gains based on crops previously shown to respond positively to such conditions. Experimental results indicate that unpowered photovoltaic shading not only moderates soil temperatures but also enhances soil moisture conservation relative to unshaded conditions. This study demonstrates that agrivoltaic systems, even after the cessation of power generation, can continue to deliver meaningful agronomic and economic value through passive shading and policy frameworks should adapt to this dual-use reality. Integrating agronomic co-benefits into decommissioning policy supports long-term farm productivity and climate resilience. Full article

Despite South Africa’s robust environmental legislation governing the mining industry, abandoned coal mines persist as a significant environmental concern, largely due to some companies evading accountability. This study assesses the level of contamination at an abandoned coal mine site in Mpumalanga, South Africa, and proposes preliminary remediation strategies and potential site repurposing options. The analysis included measuring parameters such as pH, electrical conductivity (EC), sulphates (SO₄), calcium (Ca), iron (Fe), manganese (Mn), magnesium (Mg), and lead (Pb) in both soil and water samples. Additionally, soil samples were analyzed for ammonia (NH₃), while water samples were analyzed to determine total suspended solids (TSSs) and total dissolved solids (TDSs). The results revealed that soil samples exceeded prescribed thresholds for SO₄ and Pb, according to Soil Screening Values 1 (SSV1) for protection of land and resources. Water samples also showed exceedances for several parameters, except for Mg and Pb, as per South African National Standards and guidelines. Water quality assessment using the Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI) yielded scores of 43.33 and 15.56, indicating poor quality for livestock watering and unsuitability for domestic use, respectively. These results suggest threatened water conditions, highlighting significant implications for human health and ecosystem. The study recommends a circular economy-driven approach to environmental remediation, where acid mine drainage is treated using passive systems like constructed wetlands, and phytomining is used to extract valuable metals or minerals. Invasive alien species are harvested and converted into compost, reducing waste and promoting sustainable land use. This approach not only restores the site but also generates economic opportunities through resource recovery, paving the way for sustainable post-mining land uses. Full article

This study presents a comprehensive bibliometric analysis of 217 publications on nanomaterials for soil and groundwater remediation, sourced from the Scopus database, covering the period from 2010 to 2024. The findings highlight significant contributions from various countries, with India identified as the leading contributor, followed by China and the United States. This reflects robust international collaboration in addressing environmental contamination. The analysis also identifies influential journals in this field, particularly “Science of the Total Environment” and “Environmental Science and Technology”, which are recognized for their high citation impact and play a crucial role in disseminating research findings and advancing knowledge in nanomaterials for environmental remediation. A keyword co-occurrence analysis reveals six distinct clusters that emphasize critical research themes. The first cluster focuses on environmental toxicity, underscoring the risks posed by contaminants, particularly heavy metals and emerging pollutants such as PFAS, highlighting the need for advanced monitoring strategies. The second cluster showcases innovative nanoremediation technologies, particularly zero-valent iron (nZVI) and carbon nanotubes (CNTs), which are noted for their effectiveness in pollutant removal despite challenges like surface passivation and high production costs. The third cluster addresses heavy metals and phytoremediation, advocating integrated strategies that enhance crop resilience while managing soil contamination. The fourth cluster explores photocatalysis and advanced oxidation processes, demonstrating how nanomaterials can enhance pollutant degradation through light-activated catalytic methods. The fifth cluster emphasizes adsorption mechanisms for specific contaminants, such as arsenic and pharmaceuticals, suggesting targeted remediation strategies. Finally, the sixth cluster highlights the potential of nanomaterials in agriculture, focusing on their role in improving soil fertility and supporting plant growth. Overall, while nanomaterials demonstrate significant potential for effective environmental remediation, they also pose risks that necessitate careful consideration and further research. Future studies should prioritize optimizing these materials for practical applications, addressing both environmental health and agricultural productivity. Full article

The enrichment of cadmium (Cd) in farmland soil poses serious risks to agricultural safety and remains challenging to remediate. This study evaluated CaAl-layered double hydroxide (CaAl-LDH) as a highly efficient and stable passivator for Cd-contaminated soil. Laboratory adsorption tests demonstrated that Cd²⁺ adsorption on CaAl-LDH followed pseudo-second-order kinetics and the Langmuir model, indicating monolayer chemisorption, with a maximum capacity of 469.48 mg·g⁻¹ at pH 6. The adsorption mechanisms include surface complexation, interlayer anion exchange, dissolution–precipitation, and isomorphic substitution. A three-year field trial in Yongkang City, China showed that CaAl-LDH promoted the transformation of Cd in rhizosphere soil from the ion exchange state (F2) to the residual state (F7) and Fe–Mn oxidized state (F5), reducing the exchangeable Cd content by 26.71%. Consequently, Cd content in rice grains decreased by 68.42% in the first year and remained over 37% lower in the second year, consistently below the national food safety limit. Future research should focus on the optimization of material’s stability and application protocol. The results demonstrate that CaAl-LDH provides a cost-effective and sustainable strategy for the in situ passivation remediation of Cd-contaminated farmland, contributing to food safety and sustainable agriculture. Full article

Functional hydrogels are a growing class of soft materials. Functional hydrogels are characterized by their three-dimensional (3D) polymeric network and high water-retention capacity. Functional hydrogels are deliberately engineered with specific chemical groups, stimuli-responsive motifs, or crosslinking strategies that impart targeted biomedical or environmental roles (e.g., drug delivery, pollutant removal). Their capacity to imitate the extracellular matrix, and their biocompatibility and customizable physicochemical properties make them highly suitable for biomedical and environmental applications. In contrast, non-functional hydrogels are defined as passive polymer networks that primarily serve as water-swollen matrices without such application-oriented modifications. Recent progress includes stimuli-responsive hydrogel designs. Stimuli such as pH, temperature, enzymes, light, etc., enable controlled drug delivery and targeted therapy. Moreover, hydrogels have shown great potential in tissue engineering and regenerative medicine. The flexibility and biofunctionality of hydrogels improve cell adhesion and tissue integration. Functional hydrogels are being explored for water purification by heavy metal ion removal and pollutant detection. The surface functionalities of hydrogels have shown selective binding and adsorption, along with porous structures that make them effective for environmental remediation. However, hydrogels have long been postulated as potential candidates to be used in clinical advancements. The first reported clinical trial was in the 1980s; however, their exploration in the last two decades has still struggled to achieve positive results. In this review, we discuss the rational hydrogel designs, synthesis techniques, application-specific performance, and the hydrogel-based materials being used in ongoing clinical trials (FDA–approved) and their mechanism of action. We also elaborate on the key challenges remaining, such as biocompatibility, mechanical stability, scalability, and future directions, to unlocking their multifunctionality and responsiveness. Full article

A permeable reactive barrier (PRB) containing zero-valent iron (ZVI) is an in situ groundwater remediation technology that passively intercepts and treats contaminated groundwater plumes. Over time, secondary mineral precipitation within the PRB diminishes porosity and hydraulic conductivity, altering flow paths, residence times, and sometimes causing bypass of the reactive zone. This study utilizes the THMC software to simulate porosity reduction in a PRB, capturing the coupled effects of fluid flow and geochemical interactions. The simulation results indicate that porosity loss is most significant at the PRB entrance and stabilizes beyond 0.2 m. Porosity reduction is primarily caused by aragonite, siderite, and ferrous hydroxide precipitating in pore spaces. The model further elucidates the influence of groundwater chemistry, demonstrating that variations in bicarbonate concentrations significantly impact mineral precipitation processes, thereby leading to porosity reduction. Furthermore, the study highlights reaction kinetics, with anaerobic iron corrosion rates being critical in controlling porosity reduction via mineral precipitation. THMC software effectively simulates porosity reduction in PRBs, identifies key factors driving clogging, and informs design optimization for long-term remediation. Full article