Chain elongation fermentation offers a promising route for converting organic waste into medium-chain fatty acids (MCFAs), which have higher energy density and market value than short-chain fatty acids (SCFAs). This chapter provides a comprehensive and critical synthesis of the principles, key parameters, and enhancement strategies for chain elongation technology. We first elucidate the underlying carbon and energy metabolism via the reverse β-oxidation (RBO) and fatty acid biosynthesis (FAB) pathways, emphasizing the thermodynamic drivers and key enzymatic steps. The roles of various electron donors (e.g., ethanol, lactate) and acceptors (e.g., acetate) are discussed, alongside the importance of functional microorganisms, moving from pure cultures to the ecological dynamics within mixed reactor microbiomes. We critically evaluate critical operational factors affecting MCFAs production, including pH, hydrogen partial pressure, reactor configuration, and substrate composition, within a unified conceptual framework. Strategies to enhance performance (such as inhibiting methanogenesis, suppressing the acrylate pathway, and implementing in situ product extraction) are assessed for their effectiveness and trade-offs. Despite challenges like product inhibition and competitive metabolic pathways, chain elongation remains a sustainable and economically viable approach for resource recovery from organic waste, contributing to circular economy and carbon reduction goals. This review concludes by identifying key knowledge gaps and proposing future research directions to accelerate industrial adoption of chain elongation technology.

Polycyclic aromatic hydrocarbons (PAHs) in soils of energy chemical industrial plants pose considerable ecological and health risks. However, comprehensive studies between petrochemical and coal chemical plants in arid Northwest China remain limited. In this study, 75 surface soil samples (0-20 cm) were collected from 15 large-scale plants (four petrochemical and 11 coal chemical plants) across the region. Sixteen priority PAHs (∑PAHs) were quantified, and source apportionment was conducted using diagnostic ratios and principal component analysis-multiple linear regression (PCA-MLR). In addition, health risks were evaluated using toxic equivalence factors and incremental lifetime cancer risk (ILCR) models. Results showed a stark contrast in PAHs concentrations, with coal chemical plants averaging 4652.2 ng/g and reaching up to 188,506.0 ng/g at a coal tar processing site, compared to 225.6 ng/g in petrochemical plants. Four-ring PAHs were predominant, accounting for 64.5% and 52.1% of total PAHs in coal chemical and petrochemical soils, respectively, indicative of high-temperature combustion sources. PCA-MLR analysis identified coal combustion as the dominant source at coal chemical sites (96.5%), while petrochemical sites exhibited mixed sources, including oil leakage (49.6%) and vehicular emissions (25.6%). Health risk assessment revealed that ILCR values exceeded the US EPA threshold of 10-6 at seven sampling points in coal chemical plants, with the highest risk observed at site BXT-2 (1.99 × 10-4), primarily driven by dermal and oral exposure to benzo[a]pyrene. These findings highlight the urgent need for stricter control of high-temperature industrial processes and improved management of hazardous waste in energy chemical industrial plants.

Per- and polyfluoroalkyl substances (PFASs) are widely used in the textile dyeing industry resulting in textile dyeing wastewater being discharged as a significant source of PFASs in aquatic environments. However, very limited information is available on the occurrence and fate of PFASs among different textile dyeing wastewater treatment processes. This study investigated thirteen targeted PFASs across 15 textile dyeing enterprises (abbreviated as A1-A15), 4 wastewater treatment plants (abbreviated as WWTPs 1-4), and 5 receiving surface waters. Specifically, WWTP-1 and WWTP-2 were equipped with an anaerobic-anoxic-oxic (A2/O) process, while WWTP-3 and WWTP-4 with an anoxic-oxic (A/O) process. Four WWTPs respectively treated raw textile dyeing wastewaters from A1-A6, A7-A11, A12 and A13, and A14 and A15 for standard emission. Results indicated that the total concentration of 13 PFASs (Sigma 13PFASs) ranged from 23.80 to 1867.33 ng L-1 in raw textile dyeing wastewaters, with short-chain perfluorocarboxylic acids (PFCAs) accounting for 60%. The comparison of two different treatment processes demonstrated that the A2/O process was more effective for the removal of long-chain PFCAs, which was attributed to the transformation of long-chain PFASs by the anaerobic environment. Moreover, the Sigma 13PFASs in five surface waters were 235.46 to 2787.03 ng L-1, and the correlation analysis revealed significant similarity of PFAS composition among surface waters with A3, A11, and WWTP-1 effluent (p < 0.01). Overall, this study comprehensively investigated the PFAS occurrence and fate in textile dyeing wastewater and receiving rivers along associated wastewater treatment processes, thus providing new insights into different textile dyeing wastewater treatment processes for PFAS dynamic alteration.

The co-dissemination of metal resistance genes (MRGs) and virulence factor genes (VFGs) in landfill leachate pathogens poses a significant yet underquantified public health risk. To address this gap, this study used metagenomic analysis to assess MRG/VFG occurrence and removal efficiency, and proposed a novel metal resistance index (MRI)-virulence risk index (RVI) framework to quantify microbial risks across raw, ultrafiltered, reverse-osmosis-treated leachate and adjacent groundwater in Hohhot, China. Metagenomic analyses identified 175 MRGs and 1024 VFGs, highlighting significant co-occurrence patterns (Spearman R > 0.6, P < 0.05) among dominant pathogens, including Pseudomonas aeruginosa and Escherichia coli. The results of PCoA analysis showed that the leachate treatment process could significantly change the spectrum of virulence gene and heavy metal resistance gene in the leachate. Linear regression analysis (all P < 0.001) revealed significant positive correlations between treated leachate and groundwater microbial VFGs/MRGs across seasons. Summer showed the strongest associations (R2: 0.733-0.892), followed by moderate correlations in spring (R2: 0.364-0.698) and autumn (R2: 0.349-0.642), with spatial heterogeneity in BG3 and marked seasonal impacts overall. MRI, RVI, and the MRI/RVI ratio increased sequentially after treated, indicating that high-risk microbial traits persist post-treatment. Importantly, this elevated MRI/RVI ratio is attributable to the relative proportional increase of high-risk genes rather than an absolute rise in their abundance. Our results demonstrate the leachate treatment partially mitigates heavy metal resistance/virulence loads but fails to eliminate all high-risk genes, revealing seasonal MRG-VFG co-enrichment and treatment efficacy. The MRI-RVI framework guides leachate management optimization for environmental and public health.

Textile dyeing industry is a substantial contributor to environmental per- and polyfluoroalkyl substances (PFAS) contamination due to the use of PFAS-containing auxiliaries for achieving waterproofing, oil resistance, antibacterial, or UV resistance. However, auxiliary-driven PFAS profiles along source discharge to wastewater treatment and receiving river remains unclear for differential textile dyeing processes. This study investigated thirteen typical PFASs in 21 textile dyeing plants, covering four production processes (like nature fabric, silk, synthetic fabric, and home textile). Each plant was equipped with self-treatment facilities for raw production wastewater pretreatment, and followed by two centralized wastewater treatment plants (WWTPs 1-2) for advanced treatment and standard emission to receiving river. Results revealed total PFAS concentrations (& sum;(13PFAS)) varied substantially among nature fabric (60.1-396.9 ng/L), silk (364.0-787.4 ng/L), synthetic fabric (35.4-6383.9 ng/L), and home textile (210.4-1766.1 ng/L). Meanwhile, perfluorobutane sulfonate acid (PFBS) dominated natural fabric raw wastewater, while perfluorooctanoic acid (PFOA) prevailed in other processes, which was related to the types of PFAS-containing auxiliaries used in differential processes. Moreover, self-treatment processes effectively removed PFBS with air flotation and biochemistry, but increased & sum;(13PFAS) in silk, synthetic, and home textile discharges due to chain shortening and transformation. Centralized WWTPs further increased effluent & sum;(13PFAS) by 83-242%, accompanied by PFAS redistribution into sludge (22.0-25.3 mu g/kg). Receiving river samples contained & sum;(13PFAS) of 341.3-713.4 ng/L, and perfluorooctane sulphonate, perfluorobutanoic acid, and perfluoropentanoic acid were identified as priority substances by risk evaluation. Overall, this study demonstrated the critical role of auxiliary-specific sources and treatment configurations in PFAS emission from textile dyeing industry.

Municipal wastewater treatment plants (MWWTPs) are both sinks and sources of per- and polyfluoroalkyl substances (PFAS) due to limited removal efficiency in current treatment systems. However, the role of treatment processes, especially disinfection, in altering PFAS and microbial communities remains underexplored. In this study, we investigated the occurrence of 17 PFAS in two MWWTPs in Northwest China and characterized microbial communities through metagenomic sequencing. Results showed that total PFAS concentrations increased from 56.8 to 60.3 ng/L in MWWTPA and from 5.1 to 19.1 ng/L in MWWTPB, indicating ineffective removal. Perfluoropentanoic acid (PFPeA) and perfluorononanoic acid (PFNA) dominated the influent, accounting for 86.6% and 33.3% in MWWTPA and MWWTPB, respectively. In contrast, perfluorooctanesulfonic acid (PFOS, 46.8-52.4%) and perfluorooctanoic acid (PFOA, 5.1-8.9%) concentrations increased markedly in the effluent, becoming the predominant PFAS. Meanwhile, disinfection also altered microbial diversity and homogenized community structures between the two MWWTPs. Further analysis revealed strong associations (p < 0.01) between elevated PFAS levels and specific microbial taxa, including Actinomycetia and Thermoprotei, alongside increased relative abundance of genes annotated as haloacid dehalogenases, monooxygenases, and cytochrome P450. These associations may reflect potential influences on PFAS precursor dynamics. Overall, these findings highlight the importance of considering both chemical and microbial shifts when evaluating PFAS behavior during wastewater treatment.

Organophosphate esters (OPEs) are emerging endocrine-disrupting chemicals, yet their sex-specific effects on maternal and neonatal health remain unclear. This study quantified eleven OPEs in 467 maternal serum samples and examined their associations with fetal growth (estimated fetal weight z-scores), neonatal Apgar scores, and pregnancy complications (retained fetal membranes, meconium-stained amniotic fluid, postpartum hemorrhage, and blood loss). TCIPP exposure was associated with increased postpartum blood loss, whereas TPHP was linked to reduced blood loss. TNBP increased the risk of meconium-stained amniotic fluid, while TPHP was associated with a lower risk. Significant sex-specific differences were observed: TPHP was linked to higher Apgar scores in female infants; TEP and TCIPP increased the risk of meconium-stained amniotic fluid in pregnancies with female infants, while TNBP was associated with a higher risk of retained fetal membranes in pregnancies with male infants. Mixture exposure analysis revealed that higher OPE exposure was linked to reduced fetal weight and decreased postpartum hemorrhage risk in male infants, whereas a lower risk of meconium-stained amniotic fluid was observed in mothers of female infants. The findings provide new evidence of sex-specific effects of prenatal OPE exposure on maternal and neonatal health, highlighting the potential role of environmental pollutants in pregnancy outcomes.

Antibiotics persist in urban aquatic environments and promote the spread of antimicrobial resistance, yet their removal wastewater treatment plants (WWTPs) remain insufficiently evaluated. This study investigated eight WWTPs located in inland river basins of the Tianshan Mountains in Northwest China. A total of 40 antibiotics were quantified in influent, treatment units, effluent, and dewatered sludge. Based on their solid-liquid separation processes, WWTPs were classified into Group A (secondary clarification) and Group B (membrane-based processes). Antibiotics were prioritized using a multi-criteria framework incorporating exposure, persistence, bioaccumulation, ecological risk, and resistance potential. Influent was dominated by quinolones (ofloxacin, norfloxacin), macrolides (azithromycin, lincomycin), and sulfonamides (sulfamethoxazole), with concentrations ranging from 62.5 to 472.6 ng/L. Effluents contained elevated levels of ofloxacin (331.5 ng/L), azithromycin (90.0 ng/L), and clindamycin (30.2 ng/L), while sludge concentrations remained low (0.8 ng/g). Removal efficiencies varied widely (-104.7% to 96.3%), indicating substantial process-dependent variability. Group B achieved significantly higher overall removal than Group A, with a 77.6% greater mean efficiency (p = 0.02, ANCOVA), reflecting biodegradation was the main reason for the increased efficiency of antibiotic removal. Risk assessment identified macrolides (azithromycin, roxithromycin, clindamycin) and quinolones (ofloxacin, norfloxacin) as critical pollutants. These findings provide a scientific basis for WWTPs upgrades and targeted strategies to mitigate antibiotic pollution in Northwest China.

Pharmaceuticals and personal care products (PPCPs) in landfill leachate may pose potential risks to the surrounding soil and aquatic environments. This study systematically investigated the occurrence, composition, and regional distribution of PPCPs in landfill leachate across China and quantified the influence of anthropogenic drivers. Leachate samples collected from 13 municipal landfills were analyzed for 42 PPCPs using liquid chromatography-mass spectrometry. A total of 35 PPCPs were detected, with total concentrations ranging from 2.6 to 156.8 mu g/L. Artificial sweeteners dominated the PPCP profile, followed by addictive lifestyle-related substances and pharmaceuticals. Mantel analysis revealed that regional climatic conditions, particularly precipitation and temperature, significantly influenced the spatial variability of total PPCP concentrations (Mantel coefficients r = 0.31 and 0.28, respectively; p < 0.05). Anthropogenic factors showed a significant correlation with the occurrence of PPCPs in the environment, with socioeconomic factors exerting the greatest influence (R = 0.79), followed by disease burden (R = 0.61) and dietary patterns (R = 0.51). Ecological risk assessment based on risk quotients identified eight high-risk PPCPs, including gemfibrozil, bezafibrate, and cetirizine. This study provides novel insights into the occurrence and driving factors of PPCP residues in landfill leachate across China, offering a scientific foundation for region-specific environmental management and public health policies.

Earthworms serve as vital ecosystem engineers, yet their functional responses to arsenic pollution remain incompletely understood. This study investigated how the native earthworm, Metaphire guillelmi, regulated drilosphere soil physicochemical properties, greenhouse gas emission and microbial communities under arsenate exposure (EA, 30 mg kg- 1) compared with unpolluted condition (E). Corresponding treatments without earthworms (As, CK) served as controls. The results showed no significant differences in most soil properties between As and CK treatments. Earthworms significantly increased CO2 and N2O emissions and available phosphorus (AP). However, in arsenate-polluted soils (EA vs As), the stimulatory effect of earthworms on CO2 and N2O emissions was 53 % and 24 % lower, respectively, compared to that in unpolluted soils (E vs CK). In contrast, the earthworm-induced enhancement of AP was 92 % greater under arsenate pollution. Meanwhile, the earthworminduced promotions of C fixation (frdA), denitrification (napA, nirK, nosZ) and P mobilization (phoD, phnK, gcd, pqqC) gene abundance were more pronounced under arsenate exposure, whereas the promotion of C degradation gene (sga) was weakened. Bacterial ASVs (n = 22) exhibited more associations with the abundance of C, N, P transformation genes than fungal ASVs (n = 4). Specifically, Flavobacteriaceae, Chitinophagaceae, and Shewanellaceae were keystone bacteria in mediating the abundance of C, N, P transformation genes, and their abundances were higher under EA vs As than E vs CK. Therefore, arsenate exposure can alter the ecological functions of M. guillelmi, improving carbon sequestration and phosphorus mobilization, while increasing the risk of nitrogen loss. These can provide a reference for correctly evaluating the ecological functions, as well as practical applications of earthworms in arsenic-polluted environments.

Landfill leachate is a critical reservoir of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs), posing prominent risks to groundwater, especially in semi-arid regions. This study focused on the performance of landfill leachate treatment system in Hohhot (Inner Mongolia, semi-arid region), investigating the seasonal variation across three seasons (spring, summer, and autumn), migration characteristics, and control effect of ARGs/MGEs through process optimization-oriented monitoring. Metagenomic sequencing was employed to analyze four key matrices (raw leachate, ultrafiltration effluent, treated leachate, and adjacent groundwater) across three seasons. The treatment system achieved efficient removal of conventional pollutants but failed to eliminate ARGs, MGEs, and antibiotic-resistant bacteria. Instead, it enriched high-risk hosts (e.g., Pseudomonas_E) and transposases (e.g., tnpA), exacerbating horizontal gene transfer potential. ARGs abundance showed pronounced peaks in summer and autumn among the sampled seasons. Notably, the resistome profile of treated leachate was highly similar to that of groundwater, indicating incomplete ARG containment and hydrological connectivity between the treatment system and groundwater. A dual-track health-environmental risk framework was applied to the detected ARG subtypes, revealing that overall risk burden was concentrated in a small set of high-priority determinants. The top contributors were dominated by mobility- and co-selection–linked markers (intI1, tnpA, IS6100, IS26, and qacE△1) together with clinically relevant resistance genes (sul1, aacA, and aadA), underscoring the coupling between resistance functions and genetic mobility in the leachate–groundwater continuum. Collectively, these findings indicate that semi-arid landfill systems can act as both sinks and sources of high-risk resistance determinants, and they highlight the need to integrate ARGs/MGEs-targeted treatment upgrades, seasonally adaptive operational strategies, and risk-based dual-track monitoring into leachate management. This study therefore provides actionable engineering insights for optimizing leachate treatment performance and mitigating cross-media contamination in water-scarce environments.

Rivers play vital roles as sources and sinks for antibiotics； however， current studies often overlook the antibiotic contamination in northwest China， where water is scarce. Therefore， this study assessed antibiotic contamination in a typical inland river Y and its tributary P in northwest China. We used high-performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） to detect the concentrations of 39 antibiotics across five classes. Then， we used the positive matrix factorization （PMF） model to analyze the sources of antibiotics and evaluate the ecological risks. The results indicated that sulfadoxine （SDX） dominated （mean concentration： 3 734.87 ng·L-1） in all samples with a peak of 30 120.38 ng·L-1. Oytetracycline （OXY） and sulfamonomethoxine （SMM） were also detected （17.02-71.32 ng·L-1）. The PMF model revealed that antibiotics mainly originated from aquaculture and domestic sewage. Ecological risk assessment showed high ecological risks and antibiotic resistance development potential for SDX at multiple points in Y and P， warranting attention. Additionally， OXY exhibited low ecological risk and moderate resistance development potential， while SMM showed low ecological risk. Other antibiotics temporarily posed no risk to the ecological environment. This study provides a theoretical basis for antibiotic pollution prevention and risk management in the northwest inland region.

AIMS:Antibiotic resistance genes (ARGs) pose a critical public health concern, with landfill leachate serving as a significant environmental reservoir. While ARG dynamics in leachate have been investigated in various contexts, their occurrence and influence factors in semi-arid regions remain poorly understood. This study investigated the occurrence and influence factors of ARG profiles, their potential hosts, and underlying mechanisms driving their proliferation. METHODS AND RESULTS:Comprehensive metagenomic analysis of leachate samples collected from landfills of varying landfill ages (5, 10, and 20 years) in Hohhot, Inner Mongolia-a representative semi-arid region of northern China-across three seasons (autumn, spring, and summer). Metagenomic analysis revealed distinct patterns in core ARG abundances modulated by both landfill age and seasonal variations. Notably, landfill age predominantly influenced tetracycline- and glycopeptide-ARGs, while seasonal fluctuations primarily affected glycopeptide- and multidrug-ARGs. Taxonomic analysis identified Pseudomonas aeruginosa and P. fluorescens as the predominant resistant pathogens, with elevated prevalence during spring and winter compared to summer. Network analysis and metabolic pathway reconstruction demonstrated that landfill age maybe impacted ARG dissemination through modulation of carbohydrate and nitrogen metabolic pathways. This novel finding suggests a previously unrecognized mechanism linking waste decomposition stages to ARG proliferation. CONCLUSIONS:Our study provides the first systematic characterization of ARG dynamics in semi-arid landfill leachate, offering crucial insights for developing targeted strategies to mitigate ARG dissemination in these distinct ecological contexts. These findings establish a theoretical framework for understanding ARG transmission in semi-arid environments, while providing empirical evidence to inform environmental management practices.

Microplastics (MPs) present stronger adsorption performance towards hydrophobic antibiotic (like ofloxacin, OFX) after natural aging, however, the adsorption capacity of this alteration and the influence of multiple environmental factors on this adsorption behavior remain unknown. This study investigated the adsorption kinetics of polypropylene (PP) and polystyrene (PS), and their aged materials (aged PP and aged-PS) towards OFX, and compared the adsorption capacity of these four MPs under different aquatic environmental conditions, like pHs (3, 5, 7, 9 and 11), temperatures (5, 15, 25 and 35 degrees C), NaCl concentrations (10, 100, 1000, and 10,000 mg/ L), and heavy metal ion types and concentrations (Cd2 +, Zn2+, and Cu2+: 1, 5, 25, 50, and 250 mu mol/L). Results indicated that the aging behavior of PP and PS enhanced the OFX adsorption capacity by 1.4 and 1.5 times, respectively, which attributed to the increase in adsorption sites of aged-PP and aged-PS, and this result was confirmed by the extension of adsorption equilibrium time. Moreover, the adsorption behavior under different environmental factors indicated that the promoted adsorption performance caused by aging behavior of MPs might depend on the joint determination of multiple factors in actual aquatic environment. Mechanisms penetrated that the aging behavior and appropriate environmental factors could improve the van der Waals force and electrostatic interaction between MPs and OFX. Overall, this study provided novel insights for understanding the adsorption behavior of MPs towards hydrophobic antibiotics, and would contribute to the emerging contaminants control and ecological risk reduction in future work.

Phthalate (PAE) contamination in agricultural soils has attracted global attention. However, the correlation between PAE occurrence and soil properties remains not fully clear, especially in typical arid regions. This study investigated six types of PAE at 19 sites in agricultural soils of arid regions across four Northwest China cities, and the relationship between PAE profiles and soil properties (including pH, total potassium/phosphorus/nitrogen (TK/TP/TN), soil organic matter (SOM), and heavy metals) was explored. Results revealed total PAE concentrations (Σ6PAEs) ranged from 221.20 to 618.33 μg/kg, and the di-2-ethylhexyl phthalate (DEHP) and dibutyl phthalate (DBP) dominated Σ6PAEs, accounting for 75.87

This study aimed at demonstrating the influence of differential electroplating wastewater treatment processes on the occurrence of legacy per- and polyfluoroalkyl substances (PFAS) from production discharge to wastewater treatment effluent. Here, the wastewater and sludge samples were collected from one electroplating industrial park (EIP) and four electroplating plants (EPs 1-4), which equipped with centralized wastewater treatment plant or distributed wastewater treatment facilities. Among them, EIP and EP-1 respectively gather four and three different production discharges, while other EPs have one type. Results indicated that the total concentrations of thirteen PFAS (∑13PFAS) in production discharges varied among EIP (18457.24, 3126.78, 3383.61, and 1736.84 ng/L), EP-1 (9048.19, 1876.1, and 1708.84 ng/L) and EPs 2-4 (1153.8, 42042.81, and 318.82 ng/L), and the perfluorooctane sulfonate acid (PFOS) was the main PFAS in all collected discharges. Wherein the ∑13PFAS in effluents from EIP, EP-1, EP-3, and EP-4 were respectively reduced by 93%, 96%, 99%, and 61%, and that of EP-2 increased by 12.4%. By comparing the centralized and distributed wastewater treatment processes, filtration techniques (like membrane bio-reactor or reverse osmosis) were shared processes of EIP, EP-1, EP-3, and EP-4, which might be contribute to the PFOS removal. However, the process consisting of regulation, coagulation sedimentation, biochemical treatment, and precipitation of EP-2 was difficult to eliminate the PFOS, demonstrating that the differential wastewater treatment processes altered the PFAS occurrence from discharge to effluent. Meanwhile, the ∑13PFAS of sludge samples also presented that the emission of PFAS from solid phase could not be ignored after wastewater treatment. Therefore, this study revealed that the occurrence of PFAS from electroplating production discharge to effluent were closely related to wastewater treatment process, thus providing theoretical guidance for limiting emission and reducing ecological risk of PFAS from electroplating industry in future work.

AIMS:Metal resistance genes (MRGs) and virulence factor genes (VFGs) are driven by environmental factors and host immunity, respectively, and they are traditionally considered to evolve independently. However, their co-selection dynamics in landfill leachates remain poorly characterized. In this study, a multi-regional metagenomic assessment integrating environmental gradients was first presented to reveal how heavy metals shape MRG-VFG interactions and associated ecological risks in landfill leachates. METHODS AND RESULTS:Landfill leachates were collected from 13 landfills spanning six regions in China. Multi-regional metagenomic sequencing combined with co-occurrence network analysis was applied to examine pathogen-gene relationships. The results revealed pronounced regional disparities in pathogen, MRG, and VFG distribution, alongside shared features. Staphylococcus aureus and Pseudomonas aeruginosa were identified as dominant pathogens. tufA and gyrA emerged as conserved VFGs, whereas arsB and copA represented dominant MRGs. Network analysis revealed Escherichia coli, Salmonella enterica, and Acinetobacter baumannii as central nodes carrying overlapping functional genes, forming a "metal resistance-virulence" synergy module. Redundancy analysis revealed that specific heavy metals (Cu, Zn, Cr, and As) were crucial for the formation and stability of "pathogen-MRG-VFG" functional assemblies. CONCLUSIONS:This study addresses a critical knowledge gap by integrating multi-regional metagenomic evidence with environmental selection pressures. MRGs conferred survival advantages and synergized with VFGs to enhance pathogen infectivity. These findings provide insight into MRG-VFG co-selection mechanisms in landfill leachates and guide targeted monitoring to mitigate environmental and health risks.

Bisphenol A (BPA), a well-known endocrine-disrupting chemical, has garnered significant attention in environmental science and policy. BPA can enter the aquatic environment through different routes, posing potential risks even at a low concentration. In this study, a four-compartment system [water, sediment, biota (zebrafish), and submerged aquatic vegetation (Vallisneria natans)] of a point source continuous discharge microcosm was established to investigate the distribution and fate of BPA in an aquatic microcosm. The fugacity model generated predicted values were highly consistent with those of the experiments. The distribution of BPA in the model indicates that sediment was the dominant sink. The residence time of reaction and advection was 5.8 and 75.2 d, respectively, which showed that BPA was mainly removed from the aquatic microcosm through the reaction in biota (58 %). Sensitivity analysis revealed that emission data were the most influential parameters for the model output. Transfer processes between the water and biota phases had a closer relationship. This study provides technical support for pollution source management and risk assessment for BPA.

Synthesizing green, economical, and scalable photocatalysts is essential for the effective treatment of antibiotic contaminants. However, most synthetic methods depend on expensive reagents, which increase overall costs. In this study, Bi(NO3)3 & sdot;5H2O was used as the raw material, and the crystalline transition from Bi5O7NO3 to beta-Bi2O3 and alpha-Bi2O3 was optimized by controlling the calcination temperature. This approach yielded both pure-phase samples and partially transitioned Bi5O7NO3/Bi2O3 composite. The Bi5O7NO3/beta-Bi2O3 sample synthesized at 500 degrees C and labelled BO500-1 achieved almost complete removal of norfloxacin (NOR) after 120 min of visiblelight irradiation. Compared to Bi5O7NO3, alpha-Bi2O3, and beta-Bi2O3, BO500-1 exhibited 3.6, 17.3, and 11.5-fold higher rate constants. Moreover, it maintained a high degradation rate (92.7 %) after 5 cycles, demonstrating excellent recyclability. The enhanced photocatalytic activity of the composite photocatalyst was mainly due to the formation of direct Z-type heterojunctions, which efficiently separated electron-hole (e_/h+) pairs. The NOR photodegradation activity was driven by superoxide radicals (& sdot;O2_ ) and h+. The degradation pathway was elucidated using a combination of density functional theory calculations and intermediate identification. Finally, the degraded solution exhibited lower toxicity in E. coli culture assays, while in silico predictions indicated low toxicity for the identified NOR degradation intermediates. This study presents a straightforward and environmentally friendly method for fabricating heterojunction photocatalysts to remove antibiotic contaminants from water.

The production of cheap, efficient, and stable photocatalysts for degrading antibiotic contaminants remains challenging. Herein, Bi2O3/boron nitride (BN)/Co3O4 ternary composites were synthesized using the impregnation method. The morphological characteristics, structural features, and photochemical properties of the prepared photocatalysts were investigated via X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and ultraviolet–visible (Vis) diffuse reflectance spectrum techniques. BN was used as a charge transfer bridge in the ternary composites, which afforded a heterojunction between the two semiconductors. The formation of the heterojunction substantially enhanced the charge separation and improved the photocatalyst performance. The degradation activity of the Bi2O3/BN/Co3O4 ternary composites against norfloxacin (NOR) under Vis light irradiation was investigated. The degradation rate of NOR using 5-wt% Bi2O3/BN/Co3O4 reached 98% in 180 min, indicating excellent photocatalytic performance. The ternary composites also exhibited high photostability with a degradation efficiency of 88.4% after five cycles. Hydroxyl radicals (•OH), superoxide radicals (•O2−), and holes (h+) played a synergistic role in the photocatalytic reaction, where h+ and •O2− were more important than •OH. Consequently, seven intermediates and major photocatalytic degradation pathways were identified. Toxicity experiments showed that the toxicity of the degradation solution to Chlorella pyrenoidosa decreased. Finally, the ecotoxicity of NOR and its intermediates were analyzed using the Toxicity Estimation Software Tool, with most intermediates exhibiting low toxicity.