Groundwater serves as a critical source for centralized drinking water, particularly in rapidly urbanizing regions, yet its quality is increasingly threatened by heavy metals (HMs) pollution. Systematic assessments that integrate source apportionment with seasonal health risks in such settings remain limited, hindering the development of targeted protection strategies. To assess the pollution characteristics and potential health risks of HMs in groundwater in Wuzhou City, Pearl River Delta, a total of 198 groundwater samples were collected for systematic analysis during the wet season and dry season in this study. The results show that the average concentrations of Mn, Fe and Zn are the highest in the two seasons, and Mn, Fe and As often exceed the Class III water limit. Overall, the pollution level of HMs is relatively high during the dry season. Three sources of HMs were identified by principal component analysis and the absolute principal component score-multiple linear regression model: geological background (28.67 % in the dry season and 21.45 % in the wet season), mining activities (22.70 % in the dry season and 26.52 % in the wet season), and agricultural activities (24.08 % in the dry season and 32.23 % in the wet season). The calculation results of the HMs pollution index show that the average HMs pollution index during the dry season and the wet season are 18.0 and 16.1 respectively, further confirming that groundwater pollution is more prominent during the dry season. Health risk assessment and Monte Carlo simulation indicate that the non-carcinogenic risk of children is slightly higher than that of adults. The spatial distribution characteristics indicate that the health risks in the northwest of the study area are more severe. Based on the comprehensive pollution characteristics and risk assessment results, Mn, Fe and As were identified as characteristic pollutants that need to be prioritized for control. The results of this study can provide scientific support for the precise control and treatment of heavy metal pollution in groundwater in Wuzhou City, Pearl River Delta, and at the same time offer an important reference for the formulation of drinking water safety guarantee strategies in similar urbanized areas.

The disposal of the aqueous phase (HTAP) produced during the hydrothermal carbonization (HTC) of sewage sludge (SS), along with the potential environmental risks associated with the transmission of antibiotic resistance genes (ARGs) during livestock manure composting, represent two pressing challenges in environmental engineering. This study aimed to investigate the use of HTAP as a moisture regulator in chicken manure compost and its impact on the dynamics of ARGs. Metagenomic analysis identified a total of 686 ARGs in the compost, associated with 15 classes of antibiotics and multi-drug resistance. ARGs conferring resistance to aminoglycosides, tetracyclines, sulfonamides, and macrolides accounted for 17.88-25.59 %, 12.22-31.31 %, 5.23-27.56 %, and 9.22-28.65 % of the total ARG abundance, respectively. Bacillus and Actinomyces emerged as the dominant genera of drug-resistant bacteria. The application of HTAP resulted in a maximum reduction of 21.70 % in the total ARG abundance and a maximum decline of 19.34 % in the abundance of total mobile genetic elements (MGEs). Partial least squares path modeling revealed that HTAP had a positive influence on compost humification, which directly affected host microbial communities and indirectly suppressed the generation and dissemination of ARGs. These findings provide a novel approach for mitigating ARG levels in livestock manure compost.

ABSTRACT Oily sludge (OS) and polycyclic aromatic hydrocarbons (PAHs) in wastewater represent two of the most hazardous contaminants at petroleum‐polluted sites, necessitating integrated strategies for simultaneous solid–liquid phase remediation. This study proposes a sustainable waste‐to‐resource approach by converting OS into functionalized 3‐aminopropyltriethoxysilane/co‐pyrolytic carbon (APTES/CPC) for the rapid removal of PAHs from wastewater. Results indicate that the adsorption capacity of APTES/CPC is 2.11 times higher than that of co‐pyrolytic carbon (CPC). Rapid anthracene adsorption occurs within 1 min, and adsorption equilibrium is reached within 10 min. This demonstrates its potential for emergency treatment of petroleum‐contaminated wastewater. Mechanistic studies using density functional theory (DFT) revealed that ethoxy functional groups played a pivotal role by inducing electron relaxation, promoting sp 3 ‐like hybridization, and facilitating stable C─C bond formation with anthracene. This shift from physical to chemical adsorption underpins the exceptional kinetics of APTES/CPC. These findings offer a promising strategy for in situ treatment of petroleum‐contaminated wastewater using pyrolysis residues derived from OS.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent pollutants that threaten ecosystems and human health. This review examines the adsorption performance and mechanisms of biochar in PFAS-contaminated soils, emphasizing the effects of different modification strategies. Unmodified biochar typically exhibits equilibrium adsorption capacities of 10–200 mg/g for perfluorooctanoic acid (pH 6–8, adsorbent dosage 1 g/L), substantially lower than commercial activated carbon (< 800 mg/g). Acid–base treatments and metal or mineral loading generally enhance adsorption by 2–8 fold. Mechanistically, long-chain PFAS (C8–C12) are predominantly captured via hydrophobic partitioning and hydrogen bonding, whereas short-chain PFAS (C4–C6) rely on electrostatic attraction and surface complexation. Biochar modifications adjust surface area, functional groups, and charge distribution, enabling selective adsorption. Mineral- or metal-loaded biochars promote electrostatic interactions and regeneration, while oxidant or acid treatments reinforce hydrophobic and hydrogenbonding effects. Collectively, this review elucidates the multi-mechanistic and synergistic pathways governing PFAS adsorption by modified biochars and provides a framework for evaluating trade-offs among modification strategies and designing high-efficiency materials for environmental remediation.

Landfills act as critical terrestrial sources of microplastics, functioning as “leaky time capsules” continuously releasing pollutants into surrounding ecosystems. Here, we establish a prediction model to dynamically quantify microplastic generation in landfills. By calibrating 31 years of in-situ tracking at a large-scale landfill together with a nationwide field investigation across 37 landfills, we systematically identify the spatial patterns of microplastic generation in China. East China acts as a primary hotspot contributing 45.6% of the total microplastic stock. Landfills in coastal areas account for nearly one-third of the national microplastic stock despite representing only 8.3% of the total sites. Although aggressive source reduction and in-situ remediation reduce the national microplastic by 46.4% by 2050, high-risk landfills in coastal areas remain insensitive to these measures. These findings highlight the necessity of differentiated regional control measures to effectively mitigate landfill-sourced microplastic pollution. This study dynamically models microplastic generation in China’s landfills, identifying East China and coastal sites as hotspots. Aggressive mitigation could reduce national stocks by 46.4% by 2050, though high-risk coastal sites remain insensitive.

Landfills are recognized as persistent reservoirs of antibiotic resistance genes (ARGs); however, the temporal dynamics of their risk profiles after closure remain poorly understood. Because long-term monitoring of ARG risks in landfill leachate is challenging, a "space-for-time" substitution was employed to characterize ARGs, metal resistance genes (MRGs), mobile genetic elements (MGEs), and microbial hosts in landfill leachate at three stages: unclosed landfills (UL), landfills closed for 1-5 years (CF), and landfills closed for more than 6 years (CS). Metagenomic analyses identified 518 ARG subtypes across 22 classes. ARG abundance peaked in the CF stage (1.28 copies/cell), significantly higher than in UL (0.292 copies/cell) and CS (0.597 copies/cell) stages (p < 0.05). Elevated concentrations of nickel, copper, and arsenic during the CF stage promoted ARG enrichment via co-selection, primarily driven by efflux pump-mediated cross-resistance and co-resistance within ARG-MRG clusters. IntI1 was strongly linked to high-risk ARGs, indicating horizontal gene transfer as a major dissemination pathway. Key bacterial hosts, including Pseudomonas spp. and Escherichia coli, harbored both ARGs and MRGs. These findings highlight the early post-closure period (1-5 years) as a critical surveillance window and support targeted monitoring of high-risk ARGs, MGEs, indicator taxa, and heavy metals to mitigate environmental dissemination of antibiotic resistance.

Petroleum hydrocarbon contamination poses persistent environmental hazards to soil ecosystems due to its strong hydrophobicity, stability, and ecological toxicity. In this study, a redox-active co-pyrolytic carbon (CPC), prepared from oily sludge and biomass, was applied to remediate petroleum-contaminated soil, with a focus on redox-mediated biodegradation mechanisms. The results showed that CPC significantly enhanced the removal of total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons while effectively reducing soil phytotoxicity. At an optimal dosage of 3%, CPC achieved a TPHs removal efficiency of 93.07% after 180 days, with anthracene and pyrene removal reaching 89.03% and 72.45%, respectively. CPC amendment improved soil physicochemical properties, including organic matter content, porosity, and oxidation-reduction potential (ORP), thereby improving soil redox conditions and contaminant bioavailability. Notably, CPC substantially enhanced the electron transfer-related capacity of dissolved organic matter, indicating a strengthened soil redox-mediated electron transport process. This redox enhancement was accompanied by increased activities of oxidative enzymes, particularly polyphenol oxidase and CYP450, facilitating the degradation of aliphatic and aromatic hydrocarbons. Microbial analysis revealed that CPC reshaped community succession by enriching key degraders such as Microvirga, Brevibacillus, and Sphingomonas, which were strongly correlated with redox indicators and degradation efficiency. Structural equation modeling indicated that electron transfer played a central mediating role linking physicochemical regulation, enzymatic activity, and microbial metabolism. Overall, the results suggest CPC can function as an effective redox mediator, providing a sustainable strategy for mitigating the environmental hazards of petroleum-contaminated soils.

Owing to its high organic content, good digestibility, and low moisture, up-concentrated magnetic sludge (UCMS) generated by enhanced magnetic-driven up-concentration is an ideal substance for direct conversion into short-chain fatty acids (SCFAs), but fermentation is hindered by the dense floc structure of UCMS. This study investigated the feasibility of alkali thermal hydrolysis and the underlying mechanisms which enhances soluble chemical oxygen demand (SCOD) release, SCFAs efficiency, and methanogenesis. Results showed that SCOD release increased with pH and fermentation temperature. Acetic, propionic, and isovaleric acids were the predominant SCFAs components across all fermenters. The enzymatic activities of acetate kinase, oxaloacetate transcarboxylase, and butyrate kinase significantly improved after alkaline thermal hydrolysis. The optimal pH and fermentation temperature were 11 and 70°C, respectively, which yielded a maximum SCFAs concentration of 13,139 mg COD/L and a maximum SCFAs yield of 27.3%, respectively. Tryptophan-, tyrosine-, and humic acid-like substances were the dominant components of dissolved organic matters (DOMs). Microbial analysis revealed a pronounced enrichment of bacterial populations associated with hydrolysis and acidogenesis. Notably, the highest methane production, 250 mL/g volatile solids (VS), was obtained from hydrolyzed UCMS at an inoculum-to-substrate ratio (ISR) of 2.0. Mechanistically, iron species within the system facilitated potential direct interspecies electron transfer (DIET). High temperatures favored Fe(III)/Fe(II) redox cycling over pili as pathway mediators, accompanied by enhanced cellular Fe3+ uptake and improved electron transfer potential. This study therefore offers a highly efficient strategy for advancing the application of alkaline thermal hydrolysis in resource recovery from UCMS, with mechanistic insights centered on iron-mediated DIET.

Diesel hydrocarbons persist in soils and pose long-term ecological risks, yet the effectiveness of composting remediation at high contamination levels remains poorly understood. This study evaluated composting performance across a diesel contamination gradient under CPC-amended conditions. An operational transition range was identified at around 10-15% contamination, beyond which remediation performance declined markedly. Below this range, hydrocarbon concentrations decreased by more than 91.7% within 30 days and phytotoxicity was effectively eliminated, whereas contamination levels ≥15% led to substantially reduced remediation performance and persistent toxicity. Community differentiation was most strongly associated with the C10-C15 fraction, while electron-accepting capacity, dehydrogenase activity, and urease activity were identified as informative functional indicators distinguishing low- and high-contamination systems. Statistical analyses further suggested that shifts in electron transfer-related properties and enzyme activities were linked to the removal of different hydrocarbon fractions. These findings provide mechanistic insights into the threshold-dependent performance of CPC-amended composting systems and offer a basis for optimizing bioremediation strategies under varying petroleum contamination levels.

Understanding the temporal succession of soil microbial communities under multi-source composts and chemical fertilizer (CF) is critical for sustainable agriculture. This study investigated the effects of CF and composts derived from cow dung (CD), chicken manure (CM), and food waste (FW) on soil microbial community over 360 days. Composts application enhanced soil microbial diversity with distinct temporal patterns: FW provided consistent enrichment, CD caused cyclical fluctuations, and CM produced delayed positive effects. CF persistently reduced diversity and created unique ecological niches of bacteria. Microbial communities exhibited clear directional shifts over time, with key transition points at day 14 (shift to active restructuring) and day 150 (onset of stabilization). Besides, CM enriched cellulose- and hemicellulose-degrading microbes; CD promoted C/N-cycling and mutualistic microbes; FW increased nutrient-transforming functional bacteria as well as some risk-associated taxa. CF restructured the microbial community by enriching nitrogen-cycling specialists. Temporal biomarkers indicated a shift from copiotrophic to oligotrophic taxa, with 17 early abundant genera declining over time, likely contributing to necromass accumulation. Furthermore, compost fostered more complex and resilient microbial networks with greater functional diversity, whereas CF simplified community structure despite higher connectivity. Over time, networks showed fewer nodes and phased fluctuations in topology, reflecting functional reorganization from early competitive interactions toward later synergistic associations. These dynamics were linked to depletion of DOC and NH4+-N and accumulation of TN and NO3--N, causing structural simplification but tighter topological connectivity. Overall, the results emphasize the need for source-specific compost strategies to optimize soil ecosystem services.

The advanced oxidation studies have prioritized removal rates, yet quantitative evidence on PMS utilization is scarce. This study used coffee grounds as the carbon source to construct N-Co/biochar (N(50)CoCG) through a one-step hydrothermal method, and a scaled batch was prepared in a 500 mL autoclave (N(50)CoCG-500). The two catalysts exhibited highly consistent morphology, wettability, and surface chemistry, and showed comparable peroxymonosulfate (PMS) activation. Under the experimental conditions of 50 mg/L catalyst dosage and 0.02 mM PMS concentration, nitenpyram (NPR) removal reached 100 % and PMS utilization was >90 %. In a 10-day fixed-bed run, both NPR removal and PMS utilization remained >90 %, while Co leaching stayed below 6.87 mu g/L. Open-circuit potential and chronoamperometric responses showed rapid, reversible electron transfer between PMS/NPR and CoN sites, enabling a reversible Co3+/Co2+ cycle enabling >90 % PMS utilization. The one-pot hydrothermal strategy unites scalability with ultrahigh oxidant utilization, offering a scalable, oxidant-efficient catalyst oriented toward the "oxidant economy" and validated under continuous-flow conditions.

Abstract Dissolved organic sulfur (DOS) in acid mine drainage (AMD) has attracted widespread attention due to its potential metal-complexation capacity. Given the little knowledge about DOS in AMD environments, this study employs high-resolution mass spectrometry and metagenomics to investigate its occurrence, synthesis pathways, and influencing factors. The results indicate that DOS exists at a mass spectrometry intensity-weighted relative abundance of 15.8–36.0% in AMD environments, mainly in CHOS and CHONS forms, with both levels higher than those found in soil, marine, and groundwater environments. DOS is dominated by highly unsaturated compounds, with highly oxygenated and unsaturated DOS being more stable and exhibiting greater mobility. Assimilatory sulfate reduction is the primary pathway for DOS synthesis, exhibiting gene abundance 4.5 times higher than dissimilatory sulfate reduction. Iron (hydr)oxides reduce the DOS content in AMD environments by adsorbing and immobilizing highly unsaturated compounds in sediments and inhibiting assimilatory sulfate reduction and organic carbon degradation involved in DOS synthesis. Overall, this study clarifies the molecular occurrence and fate of DOS and reveals a microbial–mineral synergistic regulation mechanism, providing a fundamental basis for understanding its molecular characteristics and potential metal-complexation relevance in AMD systems.

Abstract Although converting carbonaceous components in sewage sludge into value-added esters via pyrolysis presents significant resource recovery potential, the complex temperature-dependent interconversion and the limited molecular resolution of conventional analytical techniques have impeded mechanistic elucidation and selective regulation. Here, an integrated approach combining Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), paired mass distance (PMD) network analysis, interpretable machine learning, and density functional theory (DFT) calculations was employed to elucidate the transformation network of organooxygen species (OOSs) during sludge pyrolysis and enabled the proposal of a cascade pathway governing ester enrichment. Esters, unsaturated acids, saturated acids, and peptides/amides accounted for over 95.7% of total OOSs. Ester content decreased at 300–400 °C and regenerated at 400–500 °C, consistent with hydrolysis-esterification interconversion, defining a highly reactive temperature window. Within this interval, dominant interconversion pathways of peptides/amides ⇌ acids ⇌ esters were proposed, suggesting a cascade transformation pathway of peptides/amides → unsaturated acids → saturated acids → esters. The process yielded an additional net benefit of 164.6–474.6 CNY/t over conventional sludge disposal, with a carbon mitigation potential of 776.7 kg CO2e/t. These findings provide a molecular-scale basis for engineering-directed process optimization of pyrolysis systems targeting selective ester production from organic solid wastes.

Composting forms a vital bridge between organic waste and agricultural soil. Microbial-mediated extracellular electron transfer (EET) during composting governs material and energy flows, determines compost functionality, and ultimately influences soil redox cycling. However, elucidating the EET chain from humic-reducing microorganisms (HRMs) to molecular redox sites remains a significant challenge. Here, we integrated molecular metacommunity ecology with a theoretical molecular model to probe HRM-mediated EET at microinterfaces, correlating redox sites, intermolecular interactions, and bulk-surface molecular properties. Thirty-five models corresponding to 88 HRMs were constructed, correlating electron-accepting/-donating capacity (EAC/EDC)-related molecules with HRMs. The EET chain of electron donors, HRMs, and redox sites was established based on 3D imaging snapshots of condensed molecules. In Composts I-III, 10-21, and 6-12 HRMs preferentially targeted lignin-derived polyphenols and aliphatic/protein substrates, respectively. Additionally, Luteimonas and Paenibacillus promoted diverse degradation pathways. For back-end electron acceptors, HRMs showed selective utilization of Ar-SH, Ar-COO-, and quinone from EAC-related molecules, with preferences varying by HRMs and composts. This process is significantly influenced by intermolecular interactions (H-bond, salt bridge, aromatic-H, π-stacking, and cation-π) and molecular aggregation behavior. This work offers a novel theoretical foundation for regulating the redox process during composting, enhancing resource conversion efficiency, and guiding the development of high-function compost products.

Emerging contaminants (ECs) in groundwater systems pose critical risks to global ecological security and public health. However, the exponential growth of literature and the complexity of pollution mechanisms hinder the identification of research frontiers. To address this, this study presented a systematic bibliometric analysis of 7,925 publications from the Web of Science Core Collection (1999–2024). Results identified the United States and China as dominant contributors, reflecting a multidisciplinary integration of Environmental Sciences and Engineering. Notably, 2017 served as a pivotal inflection point, marking a shift from steady accumulation to exponential growth, primarily driven by advancements in high-sensitivity detection technologies. Time-evolution analysis revealed significant thematic shifts: comparing the period 2015–2024 with 2005–2014, research interest in traditional topics like pesticides and personal care products declined by ∼ 38% and ∼ 13% respectively, while interest in persistent contaminants surged. Specifically, publications on per- and polyfluoroalkyl substances and microplastics witnessed a dramatic ∼ 59-fold and ∼ 100-fold increase, respectively. This trend reflected a fundamental paradigm shift from monitoring legacy pollutants to investigating the transport mechanisms and toxicity of persistent, complex ECs. Finally, considering the growing complexity of multi-source environmental data, this study proposed that future research should increasingly integrate artificial intelligence (e.g., deep learning) to improve risk prediction and optimize remediation strategies.

Antibiotic resistance genes (ARGs) are emerging contaminants in wastewater systems, where heterogeneous redox conditions regulate microbial community assembly and ARG dissemination. However, how within-system redox gradients generated by electrochemical configurations structure bacterial and viral processes and ultimately control ARG dynamics remains unclear. Here, we established a vertical-flow wetland (VW), a direct-current powered VW (DW), and a microbial fuel cell-coupled VW (MW), and performed metagenomic analyses of substrates adjacent to anodes and cathodes to resolve spatial ARG patterns and mechanisms. Across all systems, 478 ARG subtypes from 26 classes were detected, dominated by sulfonamide, multidrug, and tetracycline resistance genes. Electrochemical operation substantially reduced total ARG abundance, with inhibition efficiencies of 49% in DW and 73% in MW and suppressed high-risk genes such as sul1, sul2, tetG, and bacA. Pronounced divergence occurred between anodic and cathodic microenvironments, with ARG levels averaging 0.419 and 0.229 copies per cell, respectively. Redox differentiation reshaped ARG host composition, microbial diversity, ecological networks, virus-host interactions, and metabolic strategies. Cathodic reductive zones were enriched in viral auxiliary metabolic genes linked to folate pathways, potentially alleviating sulfamethoxazole-driven selection, whereas anodic oxidative environments favored outer-membrane porins and mobile genetic elements, coinciding with elevated ARG abundance and greater horizontal transfer potential. Collectively, these results highlight redox-driven microbial metabolism, viral auxiliary functions, and MGE-mediated mobility as key regulators of ARG fate in electrochemical wetlands and provide guidance for engineering redox-optimized systems to mitigate ARG dissemination.

Landfill leachate, derived from municipal solid waste landfills, is generated by external factors (e.g., rainfall erosion, solar radiation) and internal processes (e.g., physical sedimentation, chemical reactions, biodegradation). With high concentrations of heavy metals, organic pollutants, pathogens, microplastics (MPs), and antibiotics, this highly toxic effluent seriously threatens surrounding environments (soil, groundwater, etc.) and human health if improperly discharged/leaked. Thus, this paper systematically reviews the generation mechanisms, environmental behaviors, and treatment technologies of conventional pollutants (e.g., COD, BOD5, ammonia nitrogen) and emerging contaminants (e.g., MPs, PFASs, PPCPs) in leachate. To date, various technologies (e.g., adsorption, AOPs, microbial treatment, phytoremediation) have been developed to reduce leachate ecotoxicity and meet discharge standards: membrane separation and AOPs perform well among physicochemical methods, while anaerobic-aerobic coupled systems and constructed wetlands excel in biological approaches. However, leachate composition is highly heterogeneous (pollutant types/concentrations affected by landfill age, climate, etc.), greatly challenging treatment efficiency—this reduces conventional process effectiveness and raises operational time/costs. Thus, future research should focus on developing efficient, low-consumption collaborative systems, optimizing process combinations, and enhancing leachate full-life-cycle management to support sustainable landfill environmental governance.

Petroleum pollution poses a serious threat to soil ecosystems, especially in areas surrounding oil wells, where contamination should not be overlooked. Through a 35-year longitudinal study of soils surrounding oil wells, we demonstrate that petroleum hydrocarbons accumulate predominantly in the top 10 cm of soil, reducing the electron acceptor capacity (EAC) by 61.59 % (from 12.68 to 4.87 μmole-/gC) and decreasing the electron transfer capacity (ETC) by 43 %. Structural equation modeling identified ETC as the critical mediator of microbial community shifts, with EAC playing a pivotal role in sustaining redox processes. Notably, hydrocarbon accumulation triggered a microbial succession: The abundance of Actinomycetota (including genera Rhodococcus, Arthrobacter, and Rubrobacter) showed the most significant fluctuations within 2 years, while Pseudomonadota (genera Methylobacter, Thiobacillus, and Pseudomonas), which were dominant in uncontaminated soils, decreased markedly during this period. This transition coincided with peak microbial dysbiosis (microbial dysbiosis index in 2022 reached 31.41 times that of controls). Within two to four years following mild petroleum stress, the bacterial community established a new structural configuration, revealing a crucial window for ecological recovery. The coupling between ETC reduction and microbial succession highlights the pivotal role of electron flux in soil recovery. Our findings establish a mechanistic framework for ETC-targeted restoration strategies to enhance bioremediation in petroleum-contaminated soils.