Search Results (79)

Acid mine drainage (AMD) remains a critical environmental challenge in South Africa due to its severe impact on water quality, ecosystems and public health. Numerous studies on AMD management, treatment and resource recovery have been conducted over the past 20 years. This study presents a comprehensive review of research activities on AMD in South Africa from 1998 to 2025, highlighting key trends, emerging challenges and future directions. The study reveals a significant focus on passive and active treatment methods, environmental remediation and the recovery of valuable resources, such as iron, rare earth elements (REEs) and gypsum. A bibliometric analysis was conducted to identify the most influential studies and thematic research areas over the years. Bibliometric tools (Biblioshiny and VOSviewer) were used to analyse the data that was extracted from the PubMed database. The findings indicate that research production has increased significantly over time, with substantial contributions from top academics and institutions. Advanced treatment technologies, the use of artificial intelligence and circular economy strategies for resource recovery are among the new research prospects identified in this study. Despite substantial progress, persistent challenges, such as scalability, economic viability and policy implementation, remain. Furthermore, few technologies have moved beyond pilot-scale implementation, underscoring the need for greater investment in field-scale research and technology transfer. This study recommends stronger industry–academic collaboration, the development of standardised treatment protocols and enhanced government policy support to facilitate sustainable AMD management. The study emphasises the necessity of data-driven approaches, sustainable technology and interdisciplinary cooperation to address AMD’s socioeconomic and environmental effects in the ensuing decades. Full article

To investigate the remediation efficiency of different plant species on cadmium (Cd)-contaminated soil, this study conducted a pot experiment with two woody species (Populu adenopoda and Salix babylonica) and two herbaceous species (Artemisia argyi and Amaranthus hypochondriacus). Soils were collected from an abandoned coal mine and adjacent pristine natural areas within the dam-adjacent section of the Three Gorges Reservoir Area to establish three soil treatment groups: unpolluted soil (T1, 0.18 mg·kg⁻¹ Cd), a 1:1 mixture of contaminated and unpolluted soil (T2, 0.35 mg·kg⁻¹ Cd), and contaminated coal mine soil (T3, 0.54 mg·kg⁻¹ Cd). This study aimed to investigate the growth status of plants, Cd accumulation and translocation characteristics, and the relationship between them and soil environmental factors. Woody plants exhibited significant advantages in aboveground biomass accumulation. Under T3 treatment, the Cd extraction amount of S. babylonica (224.93 mg) increased by about 36 times compared to T1, and the extraction efficiency (6.42%) was significantly higher than other species. Among the herbaceous species, A. argyi showed the maximum Cd extraction amount (66.26 mg) and extraction efficiency (3.11%) during T2 treatment. While A. hypochondriacus exhibited a trend of increasing extraction amount but decreasing extraction efficiency with increasing concentration. With the exception of S. babylonica under T1 treatment (BCF = 0.78), the bioconcentration factor was greater than 1 in both woody (BCF = 1.39–6.42) and herbaceous species (BCF = 1.39–3.11). However, herbaceous plants demonstrated significantly higher translocation factors (TF = 1.58–3.43) compared to woody species (TF = 0.31–0.87). There was a significant negative correlation between aboveground phosphorus (P) content and root Cd (p < 0.05), while underground nitrogen (N) content was positively correlated to aboveground Cd content (p < 0.05). Soil total N and available P were significantly positively correlated with plant Cd absorption, whereas total potassium (K) showed a negative correlation. This study demonstrated that woody plants can achieve long-term remediation through biomass advantages, while herbaceous plants, with their high transfer efficiency, are suitable for short-term rotation. In the future, it is suggested to conduct a mixed planting model of woody and herbaceous plants to remediate Cd-contaminated soils in the tailing areas of reservoir areas. This would synergistically leverage the dual advantages of root retention and aboveground removal, enhancing remediation efficiency. Concurrent optimization of soil nutrient management would further improve the Cd remediation efficiency of plants. Full article

Organohalide-respiring bacteria (OHRB) facilitate the reductive dehalogenation of toxic halogenated compounds in the environment, which supports their growth and proliferation. Research conducted on OHRB has achieved notable advancements. However, given the intricacy of the ecosystem and the methodologies employed for microbial isolation, numerous constraints persist. Further exploration is imperative to elucidate the physiological characteristics, ecological functions, and technological applications of OHRB. This study aimed to evaluate the outcomes and insights of prior research via a bibliometric analysis of three obligate OHRB genera—Dehalococcoides, Dehalobacter, and Dehalogenimonas—over a three-decade period from 1994 to 2024, based on the Web of Science (WOS) database. The results show that research on these three bacterial genera has advanced in sequence since the initiation of studies in this field. The research area encompasses the identification and isolation of novel OHRB species, the gene sequencing of related enzymes, and the role of microorganisms in the remediation of environmental pollutants, reflecting a gradual transition from individual investigations of OHRB to the applications of microorganisms in remediating complex environmental pollution. This study systematically reviewed the past research history of this field and conducted an in-depth analysis of research hotspots. The integration of this analysis with technological development trends and practical application requirements provides a theoretical basis and innovative concepts for future research directions in the field of ecological environment restoration. Full article

Plastic waste pollution has been widely recognized as one of the most severe and pressing environmental challenges of our time, posing significant threats to ecosystem stability and human health. The transformation of plastic waste into high-value chemicals and clean energy via photocatalytic reforming technology is increasingly regarded as a promising and sustainable alternative pathway, offering dual benefits of resource recovery and environmental remediation. This review first provides an overview of the current state of research on plastic waste management. It then systematically summarizes recent representative advances in the coupling of plastic upcycling with photocatalytic technologies, with a particular focus on the potential of plastics as carbon sources in both photodegradation and photosynthetic transformation pathways, highlighting their value and future prospects. Finally, this review outlines the key scientific challenges that urgently need to be addressed in the field of photocatalytic conversion of plastic waste, and, in light of emerging research trends, proposes several promising directions for future investigation along with the authors’ perspectives. It is hoped that these insights will provide useful guidance and inspiration for the continued advancement of this field. Full article

Since water contamination has become a serious concern, more effective environmental remediation methods are required. Chitosan (CHT)-based adsorbents have demonstrated high efficacy in removing pollutants due to their unique chemical and structural properties. However, their utilization remains limited by low environmental stability and the absence of effective adsorption sites. The functional moieties of CHT can be altered to improve its performance via graft modification and crosslinking. Compared to conventional hydrogel synthesis techniques, ionizing radiation-induced fabrication, using gamma or electron-beam irradiation, offers a promising platform for innovation across diverse fields. The prime focus of this review is on ionizing radiation developed CHT-based hydrogels to remove toxic heavy metals, dyes, organic contaminants, radionuclides, and humic substances. The fabrication strategy, adsorption mechanism, and factors affecting the adsorption capacity of CHT-based hydrogels are presented. This review aims to underscore the transformative potential of ionizing radiation-induced CHT hydrogels in environmental remediation by examining current research trends and identifying future prospects. Full article

This article provides a systematic review of the current research status and latest progress in the field of mine ecological restoration. Using the SCI literature indexed by the Web of Science database as the data source, the research status and hotspots in the field of mine ecological restoration are displayed through the visual analysis of CiteSpace and the progress of mine ecological restoration technology this year is systematically summarized. Through a comprehensive review of existing technological methods, it is found that whether it is physical, chemical, biological restoration, or combined restoration technology, there are respective advantages, disadvantages, and application limitations. Physical remediation is a pretreatment, chemical remediation is prone to secondary pollution, while the sustainability shown by bioremediation makes it dominant in the of mine ecological remediation, but it has a long cycle and there is a risk of heavy metals that are accumulated by plants re-entering the biosphere through the food chain. Combined remediation can integrate the advantages of different restoration technologies and is the trend for the future development of mine ecological restoration. In the future, we should further promote technological innovation, perfect monitoring and evaluation technology, and promote informatization, scientization, and the effective implementation of mine ecological restoration, to achieve the ecological restoration and sustainable development of the mine area. Full article

Arsenic (As) and cadmium (Cd) contamination in groundwater poses significant risks to human health and environmental sustainability. Iron–manganese minerals and associated microorganisms in subsurface environments exhibit remarkable potential for immobilizing and transforming toxic metal(loid)s through adsorption, redox reactions, and co-precipitation. This study integrates bibliometric analysis with mechanistic review strategies to systematically evaluate the roles of iron–manganese biomineralization in As/Cd stabilization. Bibliometric insights identify emerging research trends, including the application of biogenic oxides and microbial redox cycles in groundwater remediation. Mechanistic analysis reveals how microbial–mineral interactions regulate As/Cd sequestration, emphasizing the influence of environmental factors such as pH, redox conditions, and microbial metabolic pathways. Case studies demonstrate the viability of in situ remediation technologies leveraging these biogeochemical processes, though challenges persist in achieving consistent field-scale performance and long-term stability. Future efforts should prioritize optimizing microbial consortia, advancing real-time monitoring systems, and integrating biogeochemical strategies with engineered barriers. By synthesizing quantitative trends and mechanistic principles, this work provides actionable frameworks for enhancing natural attenuation and designing sustainable remediation systems for metal-contaminated groundwater. Full article

The growing diversity and prevalence of contaminants of emerging concern (CECs) in aquatic environments present significant risks to human health and ecosystems, necessitating the development of effective remediation strategies. Advanced oxidation processes (AOPs) have emerged as a promising solution due to their ability to produce highly reactive species that efficiently degrade persistent contaminants. Among the various oxidizing agents, peracetic acid (PAA) has attracted significant attention in the field of water treatment for its powerful oxidative properties, environmentally safe decomposition, and ease of use. This article is designed to offer a comprehensive overview of the latest trends in PAA-based AOPs. The discussion begins with an overview of the intrinsic performance of PAA, emphasizing its oxidation potential and degradation mechanisms. Subsequently, the effectiveness of PAA-based AOPs in remediating CECs is explored, focusing on transition metal-mediated activation (Fe, Co, Mn), UV irradiation, and carbon-based catalysts, all of which enhance the generation of reactive species (RS). Next, the determination of RS in PAA-based AOPs is examined, distinguishing between free radical (organic and inorganic) and non-radical (singlet oxygen and high-valent metal) mechanisms that govern pollutant degradation. Then, key factors affecting the removal of CECs in PAA-based AOPs, including initial PAA concentration, catalyst dosage, and pH, are also addressed. Following that, the potential by-products and hazard assessments associated with PAA oxidation are discussed. Finally, current challenges and future research directions are proposed to facilitate the large-scale application of PAA-based AOPs in water remediation. Full article

Glomalin-related soil protein (GRSP), a glycoprotein primarily exuded by arbuscular mycorrhizal fungi (AMF), exerts key roles in ecological processes in terrestrial ecosystems. Nevertheless, the intricate nature of GRSP, coupled with constraints in its extraction and analytical methodologies, impedes a comprehensive understanding of its compositional attributes and ecological functions. Moreover, the scope of current GRSP research has undergone significant expansion, necessitating a comprehensive synthesis in this field. Here, we employed bibliometric analysis to systematically assess research trends and hotspots in the research field of GRSP based on 840 relevant articles indexed in the Web of Science Core Collection database. Among them, key parameters evaluated encompass publications’ quantity, highly cited articles, high-frequency keywords, and historical direct citations. These analyses illuminated the state-of-the-art of GRSP research, delineated emergent trends, and provided future perspectives. Current investigations into GRSP predominantly focus on three major topics: (i) GRSP’s nature, origin, and quantification methodologies; (ii) GRSP’s key influencing factors including agricultural management practices, climate and land use change; and (iii) GRSP’s ecological functions enhancing soil aggregate stability, C sequestration, and contamination remediation. Our findings can serve as a scholarly resource for advancing inquiries into the ecological functionalities of GRSP and its prospective applications in sustainable soil management and ecological restoration. Full article

Groundwater is an important part of maintaining the balance of the ecosystem and one of the main freshwater resources of human society. It has therefore attracted much attention in the field of the environment, in order to gain an in-depth understanding of the research hotspots, cooperation networks and development processes in the field of groundwater heavy metal pollution remediation, and objectively reflect the scientific contributions and influences of relevant countries (regions), institutions and individuals in this field. To provide researchers with a comprehensive understanding of research trends in the field of heavy metal contamination in groundwater, this study analyzes 8147 publications from 1998 to 2024 using the Web of Science Core Collection database from the ISI Web of Knowledge. Bibliometric analysis was conducted with the data visualization tools CiteSpace and HistCite Pro. The study examines key aspects such as major research institutions, and research directions, offering insights into the application and development of groundwater heavy metal pollution remediation since 1998. The bibliometric visualization analysis of the literature in this field provides valuable insights into research directions, development trends, and emerging hotspots, offering guidance for future studies on groundwater heavy metal contamination. The analysis indicates that China and India have made significant contributions to groundwater heavy metal research. Zinc, copper, lead, and cadmium are the primary water pollutants and key research targets. However, many challenges remain in heavy metal detection, including the migration and transformation pathways of heavy metals in water bodies, interference from different matrices, and the complex chemical forms in which heavy metals exist. Future research on groundwater heavy metals will continue to focus on pollution mechanisms, source identification, risk assessment and management, bioremediation, and treatment technologies. Efforts will be made to develop technologies that enable rapid, high-precision detection and efficient heavy metal recovery. Full article

Cellulose nanofibers (CNFs), cellulose nanomaterials (CNMs), and cellulose-based composites represent a convergence of material science, sustainability, and advanced engineering, paving the way for innovative and eco-friendly materials. This paper presents a comprehensive review of these materials, encompassing their extraction, preparation methods, properties, applications, and future directions. The manufacturing of CNFs and CNMs leverages diverse techniques—chemical, mechanical, and enzymatic—with each offering distinct advantages in tailoring material characteristics to meet specific needs. Strategies for functionalization and surface modification are detailed, highlighting their role in enhancing the properties of CNFs and composites while addressing challenges in scaling production to industrial levels. The structural, mechanical, thermal, optical, electrical, and biocompatibility properties of CNFs, CNMs, and their composites are explored, underscoring their versatility for applications across various industries. Cellulose-based composites, in particular, demonstrate exceptional tunable properties for specific uses, although achieving uniform dispersion remains a key technical hurdle. These materials have applications in packaging, automotive, aerospace, biomedical devices, energy storage, and environmental remediation. Emerging research trends emphasize the integration of CNFs and CNMs with advanced manufacturing technologies, promoting sustainable practices and life cycle considerations while advancing their commercialization potential. This rapidly evolving field holds immense promise for addressing global challenges by creating high-performance, and sustainable materials. This review is crucial in advancing the understanding of cellulose nanofibers, nanomaterials, and cellulose-based composites, providing valuable insights that will drive the development of sustainable, high-performance materials for a wide range of applications, ultimately addressing key global challenges. Full article

This opinion piece postulates that quantitative environmental research and public health spatial analysts unknowingly tolerate certain spatial statistical model specification errors, whose remedies constitute some of the urgent emerging trends and issues in this subfield (e.g., forecasting disease spreading). Within this context, this paper addresses misspecifications affiliated with omitted variable bias complications arising from ignoring, and hence abandoning, negative spatial autocorrelation latent in georeferenced disease data, and/or being ill-informed about reigning teledependencies (i.e., long-distance spatial correlations). As imperative academic challenges, it advances elegant and convincing arguments to do otherwise. Its two particular themes are positive–negative spatial autocorrelation mixtures, and hierarchical autocorrelation generated by hegemonic urban systems. Comprehensive interpretations and implementations of these two conjectures constitute future research directions. Important conceptualizations for treatments reported in this paper include confounding variables and Moran eigenvector spatial filtering. This paper’s fundamental implication is an advocacy for a prodigious paradigm shift, a marked change in the collective mindsets and applications of spatial epidemiologists when specifying spatial regression equations to describe either environmental health data, or a publicly transparent geographic diffusion of diseases. Full article

The electrocatalytic oxidation of urea has gained significant attention as a promising pathway for sustainable energy conversion and wastewater treatment that could address the dual goals of waste remediation and renewable energy generation. Phosphorous function groups-based catalysts have been introduced as potential electrode materials for enhancing the urea electrocatalytic oxidation reaction (UEOR) due to their unique structural properties, high stability, and tunable electronic characteristics. This review presents recent advancements in phosphorous-based catalysts (phosphates/phosphides) for UEOR. It highlights the development of novel phosphorous materials, synthesis approaches, and electrocatalytic insights into urea electrooxidation on phosphorous-based materials surfaces. Key topics include the role of different metal phosphates, surface modifications, and compositional optimizations to improve electrocatalytic efficiency and durability. Through a critical evaluation of current research trends and technological progress, this review underscores the potential of phosphate-based catalysts as environmentally friendly and efficient alternatives for sustainable waste-to-energy conversion via UEOR. The review concludes with a perspective on future directions for optimizing phosphate catalysts, scaling up practical applications, and integrating UEOR systems into renewable energy infrastructures. Full article

Arsenic contamination in sludge and sediment has emerged as a pressing environmental issue with far-reaching implications. This review delves into the multifaceted problem of arsenic contamination, focusing on its complex interactions with microbial resistance genes (MRGs). It explores the key role of microorganisms in the biogeochemical cycling of arsenic, including processes such as reduction, oxidation, methylation, and volatilization. It describes how microorganisms resist arsenic through resistance genes that encode proteins such as efflux pumps, enzymatic detoxification, and intracellular sequestration. Arsenic, a naturally occurring element, can enter sludge and sediment through various natural and anthropogenic pathways, leading to detrimental effects on environmental quality. Understanding the role of microorganisms in arsenic mobilization, transformation, and their ability to resist arsenic toxicity through MRGs is essential for effective mitigation and remediation strategies. This review discusses the sources and distribution of arsenic in sludge and sediment, the intricate mechanisms of microbial arsenic resistance, and the potential implications for environmental management and human health. It also examines current research trends and identifies areas requiring further investigation. By unraveling the interplay between arsenic contamination, microorganisms, and MRGs, this review aims to contribute to a deeper understanding of the issue and guide future research and environmental protection efforts. Full article

Heavy metal contamination is a critical factor contributing to soil degradation and poses significant environmental threats with profound implications for ecosystems and human health. Soil amendments have become an effective strategy to address these challenges by reducing heavy metal hazards and remediating contaminated soils. This review offers a comprehensive analysis of recent advancements in soil amendments for heavy metal-contaminated soils, with a focus on natural, synthetic, natural-synthetic copolymer, and biological amendments. By thoroughly examining and contrasting their remediation mechanisms and effects, this study provides a detailed evaluation of their influence on soil physicochemical properties, leachable heavy metal content, and microbial communities. Through bibliometric analysis, current research priorities and trends are highlighted, offering a multidimensional comparison of these amendments and clarifying their varying applicability and limitations. Furthermore, this review explores future prospects and the inherent challenges in soil amendments for heavy metal contamination, aiming to offer valuable insights and theoretical references for the development and selection of novel, efficient, multifunctional, environmentally friendly amendments. Full article