Based on sounding observations and urban air quality monitoring data from 2022 to 2025, this study systematically analyzes the temperature inversion characteristics from the surface up to 5000m and their effects on air pollution in seven typical polluted regions of China: the northern slope of the Tianshan Mountains, Fenwei Plain, Beijing-Tianjin-Hebei region, Sichuan Basin, Middle Reaches of the Yangtze River urban agglomeration, Yangtze River Delta, and Pearl River Delta. The results show that the frequency of temperature inversions varied markedly with height, being mainly concentrated within the boundary layer, especially the height of 0~100m. Except for the northern slope of the Tianshan Mountains and the Pearl River Delta, a secondary peak of inversion frequency occurred above the boundary layer in other regions. The inversion frequency also showed distinct seasonal variations, being more frequent in the cold season and less in the warm season. The Beijing-Tianjin-Hebei region showed the strongest intensity (2.3℃/100m), while the Middle Yangtze River region had the thickest inversion layer (178.8m). The northern slope of the Tianshan Mountains is dominated by elevated inversions, which frequently appear between 400~500m and significantly inhibit pollutant dispersion. In the Fenwei Plain and Beijing-Tianjin-Hebei region, surface inversions occur frequently and promote pollutant accumulation, especially for NO2. In the Sichuan Basin, both surface and lower-tropospheric inversions are prominent; a secondary inversion peak occurs between 2000~3800m, showing a strong accumulation effect on pollutants and differing markedly from other regions. In the Middle Reaches of the Yangtze River and the Yangtze River Delta, upper boundary-layer inversions are common but have weaker impacts on pollutants, which are mainly influenced by surface inversions. In the Pearl River Delta, inversions below 100m exert the strongest suppression on pollutant dispersion. Overall, surface inversions generally suppress the dispersion of pollutants and serve as a major driving factor for the deterioration of air quality, while middle to upper-level inversions over the complex terrain downstream of the Tibetan Plateau also make an important contribution to pollution.
Employed methodologies such as Spearman correlation and objective weather classification analyzed the spatiotemporal distribution characteristics of the correlation between surface PM2.5 and O3（hereafter P-O correlation） across 41 cities in the Yangtze River Delta（YRD） region from 2016 to 2023. It further investigated the time-lag effects and diurnal variations in the P-O correlation and assessed the impact of meteorological conditions on the P-O relationship. The results indicate that the P-O correlation in the YRD region exhibited a spatiotemporal pattern characterized by higher values in the northwest and lower values in the southeast, as well as higher values in summer and lower values in winter. During autumn and winter, the P-O correlation and its trend showed a north-south opposite spatial distribution. In summer, the daytime positive P-O correlation（0.42） was nearly twice that at night（0.22）. In contrast, the negative correlation at night in winter（-0.26） was 2.4 times that during the day（-0.11）. The average diurnal variation amplitude followed the order: summer > autumn > winter ≈ spring, and spatially, it decreased gradually from coastal to inland areas. Spring and summer were identified as the key seasons for future synergistic control of PM2.5 and O3 in the YRD region. The negative P-O correlation in spring, autumn, and winter exhibited a single-peak "∨-shaped" structure, reaching its maximum strength with a 1-hour lag. In contrast, the daytime positive correlation in summer showed a single-peak "∧-shaped" structure, peaking at a –2 hour lag. Eight circulation types were identified, each showing distinct relationships with both P-O correlations and meteorological elements. Types 2、6、and 7 were associated with positive P-O correlations, while Types 1、3、4、5 and 8 were associated with negative correlations. Type 2 and Type 1 were the predominant circulation patterns influencing positive and negative P-O correlations, in the YRD region, respectively. The meteorological factor combinations T3-RH2-V3, T3-RH1-V3, and T3-RH1-V3 were identified as the most conducive to increased positive P-O correlations in the YRD region during spring, summer, and autumn, respectively.
This study conducted online measurements of the 532 nm extinction coefficient and chemical composition of PM1 during November 2024 in Shenzhen. A combination of multiple linear regression（MLR） and machine learning（XGBoost-SHAP） models was employed to identify the major sources contributing to PM1 light extinction. The results showed that the mean light extinction coefficient during the observation period was 54.91 Mm-1, with scattering accounting for 90.0% of the total light extinction. The average mass concentrations of organic matter, sulfate, nitrate, chloride, and black carbon in PM1 were 8.36, 3.34, 1.55, 0.11, and 0.99μg/m3, respectively. The MLR model revealed that ammonium sulfate was the dominant contributor to PM1 light extinction on both clean days（40.9%） and non-clean days（37.4%）, while the contribution of secondary organic aerosol（SOA） increased on non-clean days, reaching 28.4%. The XGBoost-SHAP model indicated that ammonium nitrate, SOA, and ammonium sulfate were the main factors affecting PM1 light extinction on both clean and non-clean days, with the impact of SOA being enhanced on non-clean days. Both methods indicate that the impact of SOA in PM1 on light extinction further increases on non-clean days. In the future, Shenzhen should strengthen the control over precursors of secondary aerosols to improve its air quality and enhance visibility.
Continuous measurements of nitrous acid（HONO） and related pollutants were conducted in the urban area of Shanghai（April 2024 to March 2025）, combined with box model simulations to investigate seasonal variations, source contributions, and impacts on OH radicals. The average HONO concentration during the observation period was（1.64±1.09）×10-9, with higher levels in winter. HONO exhibited a diurnal variation with morning and evening peaks, accompanied by significant secondary formation. Simulation results showed that daytime HONO mainly originated from the homogeneous reaction of NO and OH, followed by the photo-enhanced reaction of NO2 on surfaces and aerosols, as well as direct emissions. The contribution of these heterogeneous pathways increased significantly in winter. At night, HONO primarily came from direct emissions and the heterogeneous reaction of NO2 on surfaces. The annual average OH production rate was 3.12×109h-1, occurring mainly during daytime, with the highest rate in summer and the lowest in winter. The reaction of HO2 and NO was the primary source of OH. In spring, autumn, and winter, HONO photolysis served as a secondary source of OH, with contribution rates of 5.7%, 7.1%, and 31.4%, respectively, indicating its significant impact on OH production. In summer, however, due to higher ozone（O3） concentrations, O3 photolysis contributed more to OH production than HONO photolysis.
Using observational data, ERA5 reanalysis, and a Random Forest model, this study compares the characteristics and meteorological drivers of surface ozone（O3） pollution in Southern Sichuan during the summer heatwaves of 2022 and 2024. Results indicate that O3 pollution occurred in both periods, but the 2024 episode was more severe, exhibiting longer duration, higher peak concentrations, and broader spatial coverage. Meteorologically, although daily mean and maximum temperatures during the 2022 heatwave were approximately 1℃ higher than in 2024, a marked O3 suppression effect was observed in 2022. In contrast, the 2024 period was characterized by lower relative humidity and weaker average wind speeds, conditions more conducive to O3 formation and accumulation. Synoptically, both events occurred under strengthened subtropical high pressure, enhanced solar radiation, and thermal low-pressure influence. However, more active plateau vortices in 2022 likely moderated O3 buildup. Regarding precursors, O3 formation in 2022 was predominantly VOC-limited across most areas, with NOx-limited regimes confined to the southern part. By 2024, the NOx-limited zone had expanded notably northward. A Random Forest-based prediction model developed for the region identified relative humidity and daily maximum temperature as the primary drivers of O3 variability. High temperature and low humidity were found to increase O3 concentrations by 15.12μg/m3 and 14.57μg/m3, respectively.
This study established three sampling stations at different heights（3m, 118m, and 488m） on Canton Tower in 2023 to simultaneously collect PM2.5 samples across four seasons. Carbonaceous components, including organic carbon（OC）, elemental carbon（EC）, and water-soluble organic carbon（WSOC）, were measured to investigated the pollution characteristics and influencing factors of carbonaceous aerosols in different seasons and heights.The results showed that the mass concentrations of PM2.5, OC, EC, and WSOC exhibited significant spatiotemporal variations: seasonally, concentrations were highest in winter(with PM2.5 reaching（48.60±24.30）μg/m3, OC（11.63±6.10）μg/m3, and EC（2.00±1.47）μg/m3 near the surface) and lowest in summer(with near-surface PM2.5 at（17.86±6.20）μg/m3). Vertically, concentrations of carbonaceous aerosols decreased with increasing height; for instance, EC decreased from（1.03±0.45）μg/m3 near the surface to（0.39±0.20）μg/m3 at 488m in spring, indicating the dominant influence of ground emission sources. Except in summer, when a stronger scavenging effect on OC was caused by precipitation leading to a weaker correlation between OC and EC, a strong correlation was found between OC and EC in the other three seasons, suggesting a common source. The OC/EC ratio increased significantly with altitude. Together with changes in the SOC/OC and WSOC/OC ratios, this confirmed a significant secondary organic carbon（SOC） formation process at higher altitudes. The overall order of OC/EC, SOC/OC, and WSOC/OC ratios was observed as autumn > winter > spring > summer. The OC/EC ratio near the surface was as high as 9.72±2.49 in autumn, but only 5.42±1.34 in summer. The lower ratios in summer might be related to more precipitation, while higher ratios in autumn and winter might result from enhanced biomass combustion emissions and secondary conversion processes. A positive correlation was observed between NO2, CO, SO2 and carbonaceous components in all four seasons, especially in winter, reflecting the synergistic effects of common emission sources and unfavorable diffusion conditions. Principal component analysis results indicated that biomass combustion, road dust, and emissions from motor vehicles（gasoline and diesel） significantly impacted the ground layer. At 118m, the main sources were mixed emissions from motor vehicles（gasoline and diesel）, coal combustion, and biomass burning. At 488m, the sources were mainly influenced by seasonal differences. This study provides a scientific basis for understanding the causes and mechanisms of air pollution complex in Guangzhou and for formulating corresponding pollution prevention and control strategies.
Here we focus on Anhui Province, a typical climatic transition zone, and integrate surface measurements, satellite and ground–based remote sensing, and reanalysis data for 2020～2024. Using stepwise multiple linear regression（MLR） and an ozone formation sensitivity diagnosis based on the formaldehyde-to-NO2 ratio（FNR）, we quantified the drivers of warm-season（May-September） variations in both mean and peak(98th-percentile) surface O3 and evaluated the response to precursor emission changes. Results show that warm-season mean and 98th-percentile O3 increased significantly at rates of 0.90 and 0.68×10-6/a, respectively. Under the current emission baseline, unfavorable meteorological changes characterized by warmer and drier conditions dominated the increasing trends, whereas anthropogenic emission changes slightly suppressed peak O3(-0.50×10-6/a) but could not offset meteorological forcing, leading to rapid increases in province-wide exceedance hours and days（496 h/a and 68 d/a）. FNR diagnostics using MAX-DOAS and TROPOMI indicate a systematic shift of midday ozone formation toward NOx-limited regimes across Anhui（FNR increase of 0.03～0.35/a）, consistent with the timing of O3 peaks. Extrapolation to 2030 suggests that NOx-limited conditions account for more than 80% of midday warm-season regimes. These findings suggest that deep NOx reductions remain critical for suppressing afternoon photochemical O3 peaks and reducing exceedances, while coordinated NOx-VOC controls are needed to mitigate rebound risks associated with regime shifts.
A field survey was conducted from August to September 2023 to investigate the distribution characteristics and influencing factors of low-molecular-weight organic acids（LMWOAs） in aerosols over the South China Sea, with particular emphasis on the response of their source composition to the transition between land and marine winds. The results showed that the average atmospheric concentrations of formic acid（FA）, acetic acid（AA）, methanesulfonic acid（MSA）, and lactic acid（LA） over the South China Sea in autumn were（7.10 ±4.00） ng/m3,（11.22 ±6.22） ng/m3,（24.61 ±14.48） ng/m3, and（66.67 ±44.72） ng/m3, respectively. Higher concentrations of MSA and LA exhibited a decreasing trend from coastal to offshore areas, while elevated AA concentrations were observed in the central basin of the South China Sea. In contrast, FA showed a relatively uniform spatial distribution. When the prevailing wind direction over the study area shifted from land wind to marine wind, the average concentrations of FA, AA, MSA, and LA decreased by 8.1%, 60.6%, 53.6%, and 50.1%, respectively. Positive Matrix Factorization（PMF） analysis revealed that marine biogenic emissions（34.4%）, continental dust（25.1%）, and terrestrial pollution sources（15.7%） were the dominant contributors to LMWOAs during the land wind period. In contrast, during the marine wind period, the contribution from marine sources increased markedly, with marine biogenic emissions rising to 59.6%, followed by sea salt aerosols（12.5%） and biomass burning（12.2%）. Overall, the transition in wind direction regulated the atmospheric concentration levels of LMWOAs over the South China Sea by altering their source apportionment, thereby exerting an important influence on the regional atmospheric environment and climate processes.
The Sentinel-5P/Tropospheric Monitoring Instrument（S5P/TROPOMI） provides global methane column concentration（XCH4） observations with high spatiotemporal coverage and has been widely used for regional methane emission quantification. However, retrieval uncertainties associated with clouds, aerosols, and surface albedo introduce significant errors in XCH4. Most existing emission estimation approaches rely on concentration gradients, yet these retrieval errors propagate nonlinearly within the gradient term, leading to substantial biases in inferred emissions. Taking Henan Province as a case study, this study first applies Empirical Orthogonal Function（EOF） analysis to decompose the spatiotemporal variability of XCH4 and attribute its dominant driving factors. Results indicate that methane variability over Henan is primarily controlled by large-scale atmospheric background variations, accounting for 46.8% of the total variance. Building on this, a non-model dependent mass conservation inversion framework is developed to quantify methane emission fluxes by integrating satellite observations with meteorological constraints. To explicitly address the impact of retrieval uncertainties on emission estimates, a two-step filtering strategy is proposed, combining spatial statistical screening and grid-specific dynamic thresholding. This approach effectively separates noise induced by XCH4 errors from true emission signals in both space and time. The resulting emission estimates reveal clear anthropogenic hotspots, primarily associated with coal mining activities and urban emissions, with fluxes ranging from 1.8 to 141.3μg/（m2/s）. The proposed framework successfully reduces emission noise arising from satellite retrieval errors and yields a more physically consistent regional methane emission inventory. This study highlights the critical role of uncertainty propagation in gradient-based inversion methods and provides a practical approach for improving satellite-based methane emission estimates.
To mitigate the volatilization and leaching risks of arsenic（As） in spent denitrification catalysts, this study proposes a co-treatment approach based on the magnetite pelletizing process to achieve As stabilization and environmental risk reduction.Pellets were fabricated from spent V2O5-WO3/TiO2 catalysts, magnetite concentrate, bentonite, and CaCO3. The migration,transformation, and immobilization behaviors of As were examined through oxidative roasting experiments, sequential extraction tests, and density functional theory（DFT） calculations. The results indicate that the volatilization rate of As reached 65.14% during direct roasting of the spent catalyst but decreased to 36.07% after incorporation into magnetite pellets, and further dropped to 1.28%upon CaCO3 addition, demonstrating a remarkable suppression of As volatilization at high temperatures. The inclusion of CaCO3increased the proportion of residual-state As to 96.14%, while the As concentration under standard leaching conditions was only 0.014mg/L, well below the regulatory limit of 0.5mg/L. Arsenic primarily existed as As2O5 in the spent catalyst but transformed into a more stable Ca2As2O7 phase within the CaCO3-modified pellets. The higher defect formation energy of Ca2As2O7（8.35eV） relative to As2O5（7.14eV） suggests that As exhibits enhanced structural stability in the Ca2As2O7 phase. These findings confirm that integrating spent catalysts into the magnetite pelletizing process enables efficient As immobilization and environmentally sustainable utilization, providing theoretical and technical guidance for the green recycling of hazardous-element-bearing catalysts.
The rice-based cropping system is a typical grain production system in the Yangtze River Delta region. Different agricultural practices can affect nitrous oxide（N2O） emissions from the rice-based cropping system, thereby resulting in different N2O emission factors.Based on a 10-year continuous field observation, the effects of different agricultural practices on N2O emission factors were explored from aspects of fertilizer managements, forms of straw utilization, crop rotation systems, and tillage methods. In terms of fertilizer managements,the N2O emission factors in rice seasons enhanced with the increase in nitrogen application rate, but that from wheat seasons had little correlation with nitrogen application rate. The N2O emission factors from the organic-inorganic combined application treatments in rice season, wheat season and the whole year were respectively decreased by 59%～73%, 35%～41% and 45%～48%, compared to the inorganic application treatments under the same nitrogen application level. In terms of forms of straw utilization, there was no difference in the N2O emission factors in rice season among straw returning, biochar returning and no straw returning treatments, and their average value was 0.30%. However, the N2O emission factors in wheat season from straw returning（0.67%） and biochar returning treatments（0.92%） were significantly lowered than that from no straw returning treatment（1.58%）. Totally, the N2O emission factors in the whole year from straw returning and biochar returning treatments were decreased by 38%～44% compared with treatment without straw returning（0.86%）. In terms of crop rotation systems, the N2O emission factors in the whole year from the rice-fallow system（0.59%） and rice-Chinese milk vetch system（0.38%） were respectively reduced by 31% and 56%, compared to the rice-wheat system（0.86%）. In terms of tillage methods, the N2O emission factor from no-tillage in the whole year were reduced by 26% when compared with conventional tillage（0.86%）. Therefore,when using N2O emission factors to compile regional N2O emission inventories, it is necessary to adopt differentiated N2O emission factors according to different agricultural practices in the region to accurately and effectively estimate N2O emissions.
In this study, 42 pine needle samples were collected from 10 cities within the Pearl River Delta region. The contamination levels of 17 polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/Fs) and 13 polybrominated dibenzo-p-dioxins/dibenzofurans(PBDD/Fs) were analyzed using isotope dilution gas chromatography coupled with high-resolution mass spectrometry. The results indicated that PCDD/F concentrations((71.6±30.9)(24.1～152)pg/g) in pine needles were significantly higher than those of PBDD/Fs((34.8±22.6)(8.34～99.4)pg/g). Compositionally, PCDD/Fs were mainly dominated by octachlorodibenzo-p-dioxin(OCDD), whereas PBDD/Fs were mainly constituted by 1,2,3,4,6,7,8-heptabromodibenzofuran(1,2,3,4,6,7,8-HpBDF). Correlation analysis and source apportionment via positive matrix factorization revealed that distribution of PCDD/Fs across the sampled cities was primarily influenced by agricultural activities(e.g., the historical use of organochlorine pesticides), followed by heating and combustion sources, and emissions from the paper manufacturing industry. In contrast, PBDD/Fs were mainly associated with the use of polybrominated diphenyl ethers, with their distribution patterns correlating with indicators of regional industrialization/urbanization, like total industrial output, population density, waste incineration volumes, and industrial waste gas emissions. However, factors including pine species, lipid content of the needles, altitude, and meteorological conditions at sampling sites exhibited limited influence on the concentration distribution of both PCDD/Fs and PBDD/Fs in pine needles across the Pearl River Delta.
Electric arc furnace dust（EAFD） was utilized as a raw material to successfully prepare a cobalt-doped modified catalyst（EAFD-BC） via a ball milling-calcination method, which was then employed to activate peroxymonosulfate（PMS） for phenol degradation. The optimal preparation conditions were determined as follows: cobalt doping ratio of 2%, ball-to-powder ratio of 100:1, ball milling duration of 3h, and calcination temperature of 300℃. Structural characterization confirms that the mechanical-thermal treatment constructs a stable spinel structure with uniformly dispersed cobalt active sites. Consequently, the optimized EAFD-BC/PMS system achieves rapid and complete phenol degradation（100% in 20 min） with high mineralization efficiency（77.8% TOC removal）. The catalyst exhibits excellent stability with negligible metal leaching, ensuring the biosafety of the treated effluent. Mechanistically, the degradation is driven by a synergistic non-radical/radical system, wherein singlet oxygen （1O2） plays a dominant role alongside SO4·- and ·O2- radicals.
In this study, a novel in-situ purification system specifically designed for simulated initial roof runoff was introduced and its purification performance and operational stability was systematically evaluated under varying rainfall intensities, influent pollution loads, and antecedent dry days(ADDs). A stable coupled aerobic-anaerobic regime was rapidly established by the system and, through synergistic media adsorption and biological redox processes, high pollution removal efficiencies for organic matter, nitrogen, and phosphorus were achieved, with averages of 90.7%(COD), 90.0%(TN), and 76.9%(TP). Importantly, the system's DNRA-related pathways and inhibition mechanisms were elucidated in this work. By dynamically regulating alternating forward and reverse flow, oxygen-transfer behavior and dissolved oxygen(DO) distribution were restructured by the system, effectively suppressing dissimilatory nitrate reduction to ammonium(DNRA) under extended anaerobic conditions. This innovation ensures sustained compliance with effluent TN requirements and demonstrates a robust and efficient strategy for the purification of initial rainwater.
In this study, the anaerobic-aerobic series batch reactor(AnSBR-ASBR) was used to investigate the wastewater treatment efficiency of activated sludge(AS) and anaerobic granular sludge(AGS) under the stress of polyvinyl chloride nanoplastics(PVC NPs). Meanwhile, the influence of microbial community, key metabolic pathways and functional genes were also researched. Under the influence of PVC NPs, the average removal rates of TP by the AnSBR and ASBR decreased by 30.02% and 33.75%, respectively. Additionally, when the PVC NPs concentration was 0, 25, and 50 mg/L, the PS/PN ratio in LB-EPS of the AGS increased gradually from 0.183 to 0.398 and then to 2.21. In TB-EPS of the AGS, when the PVC NPs concentration reached 25 mg/L, the polysaccharide content in TB-EPS increased by approximately 16%. At the phylum level, when the PVC NPs concentration was 0 mg/L, Bacillota dominated in the AGS(51.44%), followed by Bacteroidota(20.22%) and Actinomycetota(13.95%). When the PVC NPs concentration increased to 50 mg/L, Pseudomonadota became the dominant phylum, followed by Bacteroidota and Bacillota. At the genus level, the abundance of Raoultella in the AGS increased from 0.99% to 12.45%. Additionally, the abundance of Klebsiella increased from 0.088% to 7.22%, while the abundance of Bacteroides decreased from 7.36% to 4.36%. Furthermore, the abundances of functional genes related to phosphorus metabolism, including ppk, pstC, and pstA, decreased from 0.068%, 0.129%, and 0.125% to 0.063%, 0.121%, and 0.110%, respectively. It was indicated that PVC NPs induced the direction of microbial community succession, inhibited the expression of genes related to polyphosphate kinase and the phosphate transport system, and thereby affected intracellular energy metabolism. This may be the key microbiological mechanism underlying the decline in phosphorus removal performance of the system caused by PVC NPs.
This study developed a novel granular electrode-based micro-electric field enhanced bio-sand filter(E-BSF) system. Over 107d of continuous operation, the system's treatment performance for conventional pollutants and the representative emerging contaminant tetracycline(TC) in micro-polluted water was evaluated, and the microbial community structure was compared with that of a conventional BSF(C-BSF). Results demonstrate that the stabilized E-BSF system increased the average removal rates of ammonia nitrogen and organic matter by 17.44% and 17.32%, respectively, compared to the C-BSF, while also improving TC removal by 11.26%, indicating an enhanced synergistic removal capacity of composite pollutants. Microbial analysis revealed that the applied micro-electric field optimized the microbial community structure, promoting the enrichment of key functional groups including antibiotic-tolerant bacteria such as Armatimonadota, Nitrospirota, and Firmicutes, thereby improving the overall purification performance. By effectively integrating bio-sand filtration with micro-electric field, this study provides a viable technical solution for treating micro-polluted rural water sources and offers new perspectives for addressing emerging contaminants in biological treatment systems, contributing to the advancement of decentralized water treatment technologies in rural areas.
This study addresses the challenge of removing protonated amines from wastewater by developing a novel technology. This technology synergistically utilizes chloride ions（Cl-） and cobalt ions(Co2+) present in wastewater to activate peroxymonosulfate（PMS） for their efficient removal. In the Co2+/Cl-/PMS system（pH = 3）, the removal efficiency of protonated dimethylamine reached 100% within 110 min, with a pseudo-first-order kinetic constant and PMS utilization rate of 0.03 min-1 and 15.6%, respectively. These values are 43 and 13 times higher than those in the system without chloride(Co2+/PMS system). Orthogonal experiments indicated that the optimal concentrations of Cl-and Co2+ were 10 mmol/L and 0.252 mmol/L, respectively. Based on radical quenching experiments and electron spin resonance（ESR） analysis, non-radical hypochlorous acid（HOCl） was identified as the primary agent responsible for DMA removal. Combined with degradation product identification, a possible mechanism for the efficient degradation of protonated amines via a non-radical pathway was proposed. Moreover, this technology demonstrated good amine removal efficiency across different water matrices. The study not only provides a novel strategy for the sustainable treatment of recalcitrant protonated amines, but also establishes a new paradigm for the sustainable concept of “turning waste into treasure and treating waste with waste.”
This review provides a comprehensive synthesis of the generation mechanisms, physicochemical characteristics, and functional roles of nanobubbles(NBs) in anaerobic digestion systems. Accumulating evidence indicates that NBs can enhance gas-liquid mass transfer by several fold, thereby alleviating diffusion limitations inherent to conventional systems. Across a range of substrates and operating conditions, the incorporation of NBs has been reported to increase methane yields by 4.7% to 41.5%. In addition, NBs facilitate the breakdown of complex organic matter, contributing to improved substrate conversion efficiency. The underlying mechanisms are considered to involve a combination of enhanced mass transfer induced by physical perturbation, potential promotion of electron transfer mediated by interfacial charge effects, and the generation of reactive oxygen species(ROS) during nanobubble collapse, which may accelerate the hydrolysis and acidification of recalcitrant macromolecules. Despite these advances, key knowledge gaps remain. Future efforts should prioritize mechanistic elucidation of NB-microbe interactions, assessment of synergistic effects in mixed-gas systems, and optimization toward scalable and energy-efficient operation, thereby enabling the translation of NB-assisted anaerobic digestion from laboratory studies to practical applications.
In this study, a core-shell heterostructure photocatalyst（SA-Co-CN/TiO2） was successfully prepared, which consisted of a n-type semiconductor TiO2 as the "core" and a nitrogen-rich carbon loaded with single-atom cobalt as the "shell". This material was applied to the catalytic activation of peroxymonosulfate（PMS） for the degradation of levofloxacin（LEV） under visible light（Vis）.The results showed that, within 10minutes, the LEV removal rate increased from 22.1% in the TiO2/Vis/PMS system to 99.9% in the SA-Co-CN/TiO2/Vis/PMS system. It maintained LEV degradation rates over 95% in the pH range of 3～11, and over 10successive cycles. These results confirmed the excellent catalytic performance of the SA-Co-CN/TiO2 material. The quenching experiment and electron paramagnetic resonance spectroscopy indicated that the SO4·- and ·OH are the predominant reactive species in the SA-Co-CN/TiO2/PMS/Vis system. The ultraviolet-visible diffuse reflectance spectroscopy and photoelectrochemical tests proved that the SA-Co-CN/TiO2 has excellent visible light absorption and charge transport properties. Moreover, a continuous-flow microreactor system was constructed based on the SA-Co-CN/TiO2 catalyst, enabling the sustained and efficient degradation of pollutants. This result preliminarily validates its potential for practical application in water treatment.
The electronics industry generates a large volume of copper-containing wastewater with complex compositions. Efficient recovery of copper（Cu） from this stream offers dual benefits of pollution mitigation and carbon emission reduction, yet requires a careful balance between treatment efficiency and economic viability in process design. Due to the strong complexation affinity of the water-soluble polyelectrolyte polyacrylic acid（PAA） for Cu2+, a closed-loop “capture-separation-acidification-electrolysis” process was developed. The complexation behavior between PAA and Cu2+ was first investigated via titration. Subsequently, the separation performance of varied techniques including precipitation, centrifugation, and ultrafiltration for PAA-Cu2+ complexes was compared. A systematic investigation was conducted on the effects of Cu2+ concentration, PAA/Cu2+ molar ratio, pH value, and salinity on Cu2+ capture efficiency, as well as the selective capture behavior in a coexisting system of Cu2+, Ca2+, Mg2+, and Ni2+. Based on these findings, optimal separation conditions for complex water matrices were identified, and the feasibility of subsequent acidificationelectrolysis steps for Cu recovery and PAA recycling was comprehensively evaluated. Results indicated that during precipitation/centrifugation, the Cu2+ capture rate initially increased and then decreased with an increasing PAA/Cu2+ ratio, attributed to changes in the cross-linking structure and surface charge of the PAA-Cu2+ complexes. The optimal molar ratio increased with higher initial Cu2+ concentrations（0.5, 1 and 5 mmol/L）, corresponding to values of 1.6, 1.8 and 2.0, respectively, achieving a maximum capture efficiency of 96.3%, comparable to that achieved by ultrafiltration. Acidic conditions significantly inhibited Cu2+ capture due to PAA protonation, whereas the optimal performance was observed at pH 5～6. Salinity（i.e., NaCl concentration） exerted opposing effects on the two separation methods, i.e., the ultrafiltration retention rate increased from 82.5% to 87.6% as salinity rose from 0 to 500 mmol/L, while the centrifugation capture decreased from 80.1% to 68.7% under the same conditions. In mixed-ion solutions, PAA exhibited a higher affinity for Cu2+ over the other competing metal ions. After separation and enrichment, more than 97% of Cu2+ was released from the PAA-Cu2+ complexes using H2 SO4. During the electrolysis stage, a Cu recovery exceeding 88% was achieved after 3 hours at a current density of 4 mA/cm2. PAA maintained a regeneration efficiency above 95% over four consecutive usage cycles.
The anaerobic digestion（AD） of winery wastewater is frequently constrained by slow hydrolysis-acidification rates, limited electron transfer efficiency, and low methanogenic activity, resulting in inefficient organic conversion and biogas production. This study investigated the enhancement of an expanded granular sludge bed（EGSB） reactor treating winery wastewater via the addition of granular activated carbon（GAC）, with a focus on the reactor performance, anaerobic granular sludge（AnGS） characteristics, microbial community succession, and underlying electron transfer mechanisms. At an optimal GAC dosage of 10g/L, the chemical oxygen demand（COD） removal efficiency and biogas production reached 94.15% and 23.36L/d, respectively, representing increases of 36.65% and 58.59% compared to the GAC-free control. Furthermore, both the coenzyme F420content and electron transfer system activity were significantly increased by 69.08% and 73.76%, respectively. GAC improved system stability by accelerating the degradation of propionic and butyric acids and regulating pH. Microbial community analysis revealed that GAC substantially enriched specific electroactive bacteria（Syntrophorhabdus, Syntrophomonas, and Pseudomonas） and methanogens（Methanobacterium and Methanosaeta） involved in direct interspecies electron transfer（DIET）, where methanogens acted as electron acceptors. This enrichment strengthened interspecies electron exchange between bacteria and methanogens and elevated the metabolic rate of organic matter. KEGG-based functional prediction further indicated that GAC supplementation activated key functional genes associated with metabolic pathways. These findings provide both technical and theoretical insights for the efficient anaerobic treatment and resource recovery of winery wastewater.
Membrane fouling was a critical technical challenge in treating algae-rich water using forward osmosis（FO） technology. In this study, a sequential-filtration FO system was constructed to investigate fouling induced by extracellular organic matter（EOM） and intracellular organic matter（IOM） from algal cells under different filtration modes, including individual and sequential filtration. Under individual filtration, the most severe water-flux decline was caused by Scenedesmus obliquus EOM, reaching 32.32%. Based on XDLVO analysis, the most negative interfacial free energy with the FO membrane was obtained for this component（-12.04 mJ/m2）, indicating a strong propensity for adsorption onto the membrane surface, and this component was identified as the primary contributor to severe fouling. By contrast, under sequential filtration, higher water fluxes and lower fouling severities were achieved during reverse filtration of EOM（10.19% flux decline） and forward filtration of IOM（12.56% flux decline）, which were closely associated with their relatively lower interfacial free energies. Molecular-weight distribution analysis and confocal laser scanning microscopy（CLSM） further demonstrated that FO membrane fouling was effectively mitigated when algal-derived organic matter enriched in small-to-medium molecular-weight fractions was preferentially filtered. Overall, new insights into fouling control strategies for FO treatment of algae-rich water were provided by these findings.
From the dual perspectives of water resources and techno-economics, this study systematically analyzes the major driving forces and future development trends of ultra-large-scale membrane bioreactor(MBR) applications in municipal wastewater treatment. Increasing pressure on water resources and constraints on land availability constitute the primary external drivers promoting MBR deployment. Technological innovation and economies of scale are the core internal drivers, leading to reduced capital investment, lower operational energy consumption, and improved overall operational efficiency. The average capital investment, operating costs, and specific energy consumption of large-scale MBR projects have decreased by 30%, 39%, and 32%, respectively, compared with levels prior to 2015. Under the combined influence of stricter environmental regulations and continuous cost reductions, ultra-large-scale MBR systems have become a critical component of urban wastewater treatment and reclaimed water reuse infrastructure. Their compact design significantly reduces land requirements and construction costs. Furthermore, high-value use of reclaimed water—such as for potable or industrial purposes—can generate stable revenue streams while substantially enhancing environmental benefits by improving pollutant removal efficiency. Looking ahead, as the value of clean water continues to rise, the investment returns of MBR systems and their integrated treatment processes are expected to become increasingly attractive.
JIAO Yan-lin, YOU Ze-kai, YANG Ming-cheng, CHEN Yong-xi, XIONG Rui-hao, SONG Yi, LI Zi-yi, ZHANG Tian-qi, WANG Ya-nan, ZHANG Zhi-jie, GU Wen-wen, ZHANG Li-hui, ZHAO Jun-ping, YU Guang-fei, WANG Li-dong, DAI Qin
To address the challenge of treating organic waste amines, which arose from the widespread use of amine-based absorbents in carbon capture processes, a catalyst（CoCu-Ov-Al2O3） with ternary active sites of cobalt（Co）, copper（Cu）, and oxygen vacancies（Ov） was prepared by this study via the impregnation-calcination method. Multiple characterizations（SEM/EDS/XRD/FT-IR） were used to confirm that the Co-Cu bimetals were successfully doped into the γ-alumina（γ-Al2O3） support through non-equivalent substitution. The removal efficiency of monoethanolamine（MEA） could reach up to 100% within 40 minutes in the CoCu-Ov-Al2O3/peroxymonosulfate（PMS） system at pH=7, and a pseudo-first-order kinetic constant of 0.099 min-1 was recorded. This constant was 4.7 times and 19.8 times higher than those of the Co-Ov-Al2O3/PMS and Cu-Ov-Al2O3/PMS systems, respectively. In contrast, the Ov concentration followed the order: Co-Ov-Al2O3（64%） > CoCu-Ov-Al2O3（46.96%） > Cu-Ov-Al2O3（7.42%）. These results indicated that the synergistic effect between the bimetals and Ov was far superior to that of single metals.A series of experiments were conducted, and it was revealed that the dominant active species in the system were radical pathways(SO4·-and ·OH) and non-radical（1O2）. Additionally, the utilization of dissolved oxygen（DO） was significantly enhanced by the Ov in CoCu-Ov-Al2O3.A potential pathway for the efficient degradation of MEA via PMS activation was also proposed.Low metal ion leaching(Co:0.34×10-6, Cu:0), high environmental tolerance, and strong stability were exhibited by the catalyst.Overall, theoretical and technical support was provided by this study for the efficient and low-cost removal of MEA in industrial applications.
This study employed tannic acid to etch ZIF-67 under optimized conditions（0.17g tannic acid, 10 min etching time）, followed by carbonization at 500℃under N2 atmosphere to obtain E-ZIF-67（C）. Subsequently, epoxy resin（EP） was used as an auxiliary carrier to immobilize E-ZIF-67（C） powder onto glass, forming a composite coating（1g EP dosage）. The EP/E-ZIF-67（C） coating was then applied to activate peroxymonosulfate（PMS） for methyl orange（MO） degradation. Results demonstrated that under conditions of 10 mg/L initial MO concentration, 0.3g/L coating loading, 0.1g/L PMS dosage, and pH=7, a degradation efficiency of 89.3% was achieved within 60 minutes. Radical quenching experiments confirmed that SO4·- was the dominant reactive species in the system. After five cycles of reuse, the coating maintained a MO degradation rate of approximately 61%, with post-reaction Co2+ leaching below the 1 mg/L limit specified by China's Surface Water Quality Standards（GB 3838-2002）, effectively addressing challenges of powder catalyst recovery and metal leaching. Furthermore, the system achieved degradation rates of 58.5% and 72.0% for tetracycline and ciprofloxacin in water, respectively. The composite coating strategy proposed in this study provides an effective pathway for the engineering application of MOFs and their derivatives in advanced oxidation water treatment technologies.
LI Dong-mei, DAI Zi-qiang, ZHANG Wen-xin, CHEN Yuan, ZHANG Jin-ming, ZHU Jun-yu, CHEN Zhi-xiang, JIANG Shu-xian, LIU Zi-ye, WANG Xin-ling, LI Sha-sha, LI Xi-yang
The conventional process for treating dye wastewater has low efficiency. Membrane separation technology has been used widely due to its good retention characteristics. However, the membrane fouling behaviors affect its widespread application. In this paper, taking carbon nitride（CN）, sulfer（S） and Ag2MoO4 as raw materials, visible-light-induced photocatalyst Ag2MoO4/S@CN（AM/S@CN） was synthesized by calcination and chemical precipitation method. Then, taking the thin-film composite（TFC） polyamide membrane as a representative, a new modified TFC membrane coped with AM/S@CN was prepared through interfacial polymerization. The optimal preparation conditions and retention performance of the modified membrane were investigated. The results show that: the optimal preparation conditions are as follows: the dosage of AM/S@CN is 15 mg, the concentration of piperazine（PIP） is 1.0 wt%, the concentration of trimesoyl chloride（TMC） is 0.25 wt%, the interfacial polymerization time is 35s, and the heat-treatment temperature is 30℃. The retention rate of the modified membrane for Congo red（CR）(98.71%) is significantly higher than that of the TFC membrane（87.50%）, and its pure water flux(69.94L/（m2·h）) is 3.29 times that of the TFC membrane(21.24L/（m2·h）). The water contact angle of the modified membrane is lower than that of the TFC membrane, indicating improved hydrophilicity. Meanwhile, the maximum light absorption edge of the modified membrane redshifts from 390 nm（TFC membrane） to 465 nm, enhancing the visible-light absorption ability. Therefore, the anti-fouling performance of the AM/S@CN-modified membrane is significantly improved: its reversible fouling rate（12.31%） is 27.36 times that of the TFC membrane（0.45%）, and the irreversible fouling rate（4.41%） is significantly reduced（30.02% for the TFC membrane）. The modified membrane has significant self-cleaning performance. Its flux recovery rate increases from 69.98%（TFC membrane） to 95.59%. Moreover, the modified membrane has high stability. After five filtration-self-cleaning cycles, the flux recovery rate of the modified membrane can still reach 81.80%, and the retention rate for CR is as high as 98.21%. This new modified membrane has excellent retention performance, anti-fouling ability, and photocatalytic self-cleaning performance, providing a new research idea for dye wastewater treatment.
To clarify the migration and emission characteristics of thallium（Tl） in cement production systems, samples and data were collected from four typical production lines. The sources of Tl in the cement clinker production system and the Tl enrichment factors of materials at different positions were analyzed. Additionally, the evolution of Tl in the selective catalytic reduction（SCR）, denitration catalyst was analyzed using XRD, XPS, and SEM-EDS. The results showed that Tl originated from raw fuels and co-processed wastes, with higher Tl concentrations inaltemative fuels and wastes compared to natural raw materials, necessitating strict control of Tl input at the source. After high-temperature calcination, Tl underwent condensation and deposition, leading to obvious enrichment in process ash. The enrichment factor of Tl in waste heat boiler ash and baghouse dust reached maximum values of 12260 and 7267, respectively. Temperature variations and physicochemical reactions were identified as the primary reasons for Tl enrichment. In systems equipped with SCR equipment, Tl in the catalyst rapidly occupied the catalytic sites in the form of Tl2O3 or Tl2SO4. The Tl content in the catalyst increased rapidly from the 10-6 level to 6.39%, at which point the denitration efficiency dropped to below 5%, indicating almost complete deactivation due to poisoning. Tl migrated through internal and external cycles, with the amount of Tl circulating and enriching being hundreds of times greater than the amount discharged. Therefore, it was imperative to enhance the treatment of process ash to disrupt the Tl enrichment cycle chain, ultimately achieving whole-process control of Tl from " source-process-terminal " mamagement.
Fly ash(including economizer ash, acid-gas treatment tower ash, and baghouse fly ash) and bottom ash samples were collected from five typical municipal solid waste incineration(MSWI) plants. The speciation and distribution characteristics of arsenic(As) and selenium(Se) in these solid wastes were investigated using the Wenzel five-step sequential extraction method. Their bioavailability and leaching toxicity were further evaluated to assess potential environmental risks. The results indicate that As concentrations in MSWI solid wastes were significantly higher than those of Se, with levels generally following the order: baghouse fly ash or economizer ash > acid-gas treatment tower ash > bottom ash. The average concentrations of As and Se range from 7.06～114.87 mg/kg and 0.40～6.88 mg/kg, respectively. In economizer ash, non-specifically adsorbed As and Se account for 11.86% and 21.23%, respectively, which were notably higher than in other fly ashes. Weakly crystalline Fe-Al oxide-bound As and Se represent the dominant fractions in fly ash, with As exhibiting a substantially higher proportion than Se. Specifically adsorbed Se constitutes up to 35.50% of total Se in acid-gas treatment tower ash, while specifically adsorbed and residual Se are also the main occurrence forms in baghouse fly ash. Overall, both As and Se show high bioavailability in MSWI solid wastes. In particular, Se exhibits high leaching potential and mobility, suggesting a greater environmental risk and underscoring the need for effective management and stabilization of Se-containing incineration residues.
This study investigated the dissolved organic matter(DOM) transformation dynamics during the composting of deeply dewatered municipal sewage sludge without the addition of any exogenous bulking agents. Three-dimensional excitation-emission matrix fluorescence spectroscopy(3D EEM) and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) were employed to systematically track the temporal evolution of DOM spectral characteristics, molecular composition, and elemental ratios throughout the composting process, with particular emphasis on elucidating the transformation pathways and stabilization mechanisms of DOM at different composting stages. The results demonstrated that composting proceeded through a heating phase, a thermophilic phase, and a cooling phase, with days 2～4 identified as the most molecularly active period. Molecular composition analysis revealed that the number of DOM molecules fluctuated dynamically between 4,000 and 6,000, with structural complexity and stability increasing over time. The relative abundance of readily bioavailable CHO compounds decreased from 32% to 24%, while heteroatom-containing CHONS compounds increased substantially from 8% to 18% over the composting period. Van Krevelen diagram analysis and reaction network modeling further revealed that oxidation and dealkylation reactions dominated the molecular reorganization during days 2～4, driving a 59% increase in the proportion of recalcitrant molecules and thereby achieving molecular-level DOM stabilization. This study elucidates the molecular stabilization mechanisms of DOM during bulking agent-free composting, providing a theoretical basis at the molecular level for the precise regulation of composting reactions and the broader promotion of bulking agent-free composting technology.
A mesocosm experiment was conducted to explore the patterns and mechanisms of hexabromocyclododecane(HBCD) microbial degradation in riparian soils across a gradient of water depths(0, 30, 60, 90, 120, and 150 cm). The HBCD degradation rate increased significantly with water depth, from 4.46% at 0 cm to approximately 25% in shallow water(30, 60 cm) and further to a range of 34.8～42.4% in deep water(90, 120, 150 cm). Among the five major modules from the bacterial co-occurrence network, Modules 1～3 and 5 emerged as key ecological clusters for HBCD degradation. The partial least squares path model results demonstrated that water depth primarily enhanced HBCD microbial degradation indirectly by altering soil physicochemical properties, which in turn influenced the total bacterial community structure and the absolute abundance of organohalide-respiring bacteria. Among these factors, the absolute abundance of organohalide-respiring bacteria was identified as the most significant factor affecting the HBCD degradation rate(total effect: 0.410). In conclusion, by revealing the regulatory role of water depth on HBCD microbial degradation, this study provides a scientific basis for the future remediation of persistent organic pollutants in riparian zones.
Drawing on domestic and international research on soil heavy metals in karst areas, this paper systematically reviews recent advances in understanding the accumulation characteristics, sources, spatial distribution patterns, and migration processes. It further elucidates the transport pathways and distribution patterns of heavy metals from sources to sinks, driven by factors including weathering of mineralized lithologies, geomorphological evolution, hydrological transport, mining and metallurgical activities, agricultural inputs, transportation, and biological processes. Building on these insights, this study proposes a "pedogenic accumulation-continuous differentiation" conceptual framework to explain the spatial distribution of heavy metals in karst farmland soils. Overall, these soils show the dual characteristics of high geogenic backgrounds and strong heterogeneity." Their accumulation and differentiation are jointly controlled by lithological and hydrological-geomorphological settings, as well as human disturbances, while both natural processes and anthropogenic inputs continually enhance the migration and spatial partitioning of heavy metals in cultivated soils. This findings advance the current understanding of spatial heterogeneity in karst soil geochemistry and provide a scientific basis for effective pollution control and remediation strategies in agricultural landscapes.
Based on sand column experiments, this study investigated the removal and remediation efficiency of trichloroethylene(TCE)-contaminated sand columns under different concentrations and injection flow rates of sodium dodecyl sulfate(SDS) by combining induced polarization(IP) and electrical resistivity(ER) methods. The results show that TCE removal was synergistically controlled by injection flow rate and surfactant concentration. The optimal TCE removal performance was achieved at a high flow rate of 6 mL/min and a medium surfactant concentration of 1g/L. After injecting 6 pore volumes(PV) of surfactant, the TCE saturation decreased to 0.1 and the remediation efficiency reached 91.2%. The relative error of the removal rate obtained by the IP method ranged from-10.23% to 7.63%, while that of the ER method ranged from-13.29% to 9.31%, indicating that the IP method had a smaller monitoring error. This study verifies the feasibility of the combined IP and ER methods for dynamically monitoring the TCE removal process. The highest TCE removal efficiency is obtained under high flow rate and medium surfactant concentration, and the IP method is superior to the ER method in monitoring accuracy and stability. The findings provide technical references for the remediation and monitoring of TCE-contaminated sites.
This study examined the degradation process of biodegradable microplastics(BMPs) that made from polylactic acid(PLA), polybutylene adipate-co-terephthalate(PBAT), polycaprolactone(PCL), polybutylene succinate(PBS), and their commercial plastic bag(PBAT-B) in natural freshwater. A 300 days field experiment was conducted at different water depths(0.5m, 3m, 6m). Changes in mass loss, surface hydrophilicity/hydrophobicity, microstructure, and surface chemical composition were identified. The 16S rRNA high-throughput sequencing and FAPROTAX functional prediction were also employed to analyze the response of surface biofilm communities. The results showed that all five BMPs underwent varying degrees of degradation over the 300 days experiment, with degradation rates influenced by period of observation and water depth. The maximum degrading rate were found in PBAT, PCL, and PBS plastic in the surface layer(0.5m), followed by the middle layer(3m) and the bottom layer(6m). PBAT-B exhibited the most significant degradation at 3m depth, with a mass loss of >69.20%, while PLA displayed <4% mass loss throughout the experiment. After 300 days experiment, all plastic surfaces changed from hydrophobic to hydrophilic, showing degradation features such as roughening, pitting, and cracking, along with a significant increase in surface O/C ratios. The plastic surfaces harbored specific degrading microbial communities. Dominant genera on PBAT and PBAT-B surfaces included Hyphomicrobium, while the PCL surfaces were dominant by_Xanthobacteraceae and_Rhodocyclaceae. The microbial community exhibited distinct depth-dependent variations. The relative abundance of the Comamonadaceae family on PBAT-B surfaces showed a positive correlation with water depth, peaking at 6 m, while decreasing by 0.94% and 0.34% at 0.5m and 3m, respectively. Conversely, its abundance on PBAT substrates displayed a negative relationship with depth. Functional prediction indicated that the microorganism colonized on the plastic surfaces showed the functions related to aromatic compound degradation, hydrocarbon degradation, and nitrogen cycling, with functional intensity influenced by water depth and plastic types.
To elucidate the ecotoxicological effects of N-nitrosodimethylamine(NDMA) and its ultraviolet(UV) photolysis byproducts on cyanobacteria, Oscillatoria spp. was employed as a model organism to evaluate their impacts on algal growth, photosynthetic performance, oxidative stress responses, and cyanotoxin production. The results demonstrated that NDMA exerted a pronounced inhibitory effect on algal growth, with inhibition rates of 40.58% and 47.83% at 10μmol/L and 20μmol/L, respectively, which decreased to 34.64% and 37.88% following UV photolysis. Under exposure to NDMA photolysis byproducts, algal cell division was not completely suppressed; however, chlorophyll-a content declined markedly from 0.94 mg/L to 0.29 mg/L, corresponding to a 69% reduction, indicating a decoupled response between cell growth and photosynthesis. Both NDMA and its UV photolysis byproducts induced oxidative stress and resulted in a “decrease-rebound” pattern in microcystin concentrations. These findings indicate that although UV photolysis reduces the direct growth toxicity of NDMA, its byproducts may still pose potential ecological risks to aquatic systems by altering algal metabolic processes without triggering apparent cyanobacterial blooms.
This study was conducted within the Qinghe River Basin in Beijing, where eighteen sampling sites were established to investigate the spatiotemporal distribution and ecological risks of antibiotics. Water and sediment samples were collected during both the non-flood season(May) and the flood season(August) of 2025. Fifteen representative antibiotics were analyzed using ultra-high-performance liquid chromatography tandem mass spectrometry(UHPLC-MS/MS), providing a comprehensive understanding of their distribution patterns in the Qinghe River Basin. The Positive Matrix Factorization(PMF) model was employed to identify potential sources of contamination, and ecological risk assessments were performed. The results revealed that thirteen antibiotics were detected in the water, with total concentrations ranging from 16.56 to 419.33 ng/L, while eleven antibiotics were detected in the sediment, with total concentrations ranging from 23.19 to 466.10 ng/g. Antibiotics in the water exhibited a spatial distribution pattern characterized by higher concentrations in the upstream and downstream areas, while the middle reaches displayed lower concentrations. In contrast, the sediment demonstrated stage-specific accumulation characteristics. Source apportionment analysis indicated that medical sources contributed the largest proportion(36%) to the presence of antibiotics in the Qinghe River, with notable contributions from azithromycin(AZM), cefotiam(CTM), and ofloxacin(OFL). These sources collectively created a multi-source composite pollution pattern. Moreover, OFL and ciprofloxacin(CIP) were identified as the primary pharmaceuticals driving high risks to algae, contributing to a medium-high ecological risk throughout the river basin. Based on these findings, a targeted prevention and control management strategy was proposed, incorporating "source reduction—process interruption—risk warning—end treatment," offering a practical approach for controlling antibiotic pollution in urban reclaimed water-supplied rivers.
The frequent occurrence of cyanobacterial blooms in shallow lake ecosystems poses a serious threat to ecosystem health and drinking water safety. The key to achieving long-term control of cyanobacterial blooms is to promote the steady state transition of lakes from algal-turbid water state to grass-clear water state. The ecological restoration strategy centered on the restoration of aquatic plant communities is a feasible path to realize this transition. However, there are still a lot of questions about the occurrence mechanism of cyanobacterial blooms and ecological restoration methods that need to be clarified. Therefore, based on the systematic description of the occurrence mechanism of cyanobacterial blooms, this paper summarizes the implementation priorities, technical paths, and applicable boundaries of five types of ecological restoration methods, including internal and external nutrient reduction, habitat restoration, bio-manipulation, construction of aquatic plant communities, and emergency response, with the aim of providing a scientific basis for the management of lakes and the decision-making process.
Huixian Wetland is used as a research area in this study. Surface water(n= 23) and sediment(n= 22) samples were collected to analyze the spatiotemporal distribution characteristics of MPs. The pollution load index(PLI) and polymer hazard index(PHI) were evaluated. The results showed that the abundance of MPs in surface water and sediments in the study area showed significant differences in spatial and temporal distribution. In the wet season(WS) and the dry season(DS), the average abundance of MPs in surface water was(49.6±17.4) and(69.4±20.3) n/L, respectively, and the abundance in sediments was(19037.5±4122.84) and(25695.7±6732.14) n/kg, respectively, and the abundance of MPs in DS was higher than that of WS. In addition, the abundance of MPs showed a gradual increase along the direction of water flow. Due to the combined influence of agricultural production activities and daily discharge of residents, the main components of MPs in surface water are polyethylene(WS(36.77%±4.95%), DS(31.76%±4.00%)) and polypropylene(WS(27.02%±4.49%), DS(28.82%±6.89%)).(61.84% ±7.28%), DS(56.00%±8.55%)), while in sediments, it is mainly fragmented(WS(35.72%±5.24%), DS(39.57%±3.64%)). The ecological risk calculation showed that the pollution characteristics of MPs in surface water were "extremely strong pollution load and high risk of toxicity", and the pollution characteristics in sediments were "strong pollution load and high risk of toxicity", so the control and treatment of MPs pollution should be highly valued. The ecological risk assessment system for MPs developed in this study can provide a basis for differentiated management of MPs within the wetland system and for water environment protection.
The Zhejiang coastal waters, one of the most economically intensive marine areas, have long faced environmental challenges related to eutrophication. Despite persistent government efforts, the long-term evolution of nutrient concentrations and stoichiometry, along with their ecological effects, requires further systematic assessment. This study systematically analyzed the spatiotemporal patterns, driving mechanisms, and ecological impacts of dissolved inorganic nitrogen(DIN) and dissolved inorganic phosphorus(DIP) using long-term in-situ monitoring data from 1996 to 2024,. The results indicate that over the past three decades, DIN concentrations increased gradually until 2014 and then decreased rapidly due to source control measures in Zhejiang and coordinated emission reductions in the Yangtze River Basin. In contrast, DIP showed a complex oscillating pattern characterized by “rise-fall-rise-fall”, influenced by multiple factors such as reduced terrestrial input, the buffering effect of particulate phosphorus, and the interception effect of the Three Gorges Project, which accompanied by an expansion of absolute phosphorus limitation. Accordingly, the DIN/DIP ratio exprienced three distinct phases: low-level stability, high-level oscillation, and mid-level fluctuation, with a multi-year average of 64.1 ±142, consistently exceeding the Redfield ratio(16:1), reflecting prolonged phosphorus limitation in the region. Nutrients enrichment led to an increased frequency of red tides, a higher proportion of toxic algal species, changes in phytoplankton and macrobenthic community structures, and decreased levels of bottom dissolved oxygen. In recent years, declining DIN concentrations and a partial alleviation of the DIN/DIP imbalance have somewhat mitigated red tides and hypoxia; however, overall ecosystem recovery remains sluggish highlighting the need for sustained governance and monitoring. This study provides a scientific basis for evaluating the effectiveness of nutrient control measures and guiding future ecological restoration strategies in the Zhejiang coastal waters.
Taking the Ulanor Wetland in the Hulun Lake basin, a cold and arid region in China, as the research object. Based on field investigations, laboratory experiments were designed to examine the thermodynamics of sediment phosphorus adsorption-desorption and the mineralization of organic phosphorus（OP） under varying salinity levels（NaCl: 0～3g/L）. The effects and mechanisms of increasing salinity on phosphorus adsorption-desorption and OP mineralization characteristics in sediments were systematically analyzed. It was found that with increasing salinity, the maximum phosphorus adsorption capacity(Qmax) of sediments was decreased from 2.04 mg/g to 0.45 mg/g, while the adsorption-desorption equilibrium concentration（EPC0） was increased from 0.12 mg/L to 0.23 mg/L. During the mineralization experiments, the content and net increase rate of inorganic phosphorus（IP） in the sediments, as well as the phosphorus concentration in the overlying water, were all observed to increase with rising salinity. These findings indicated that elevated salinity reduced the phosphorus adsorption capacity of sediments, enhanced the bioavailability of sediment phosphorus, and consequently increased the risk of phosphorus release.
Crab sticks are commonly used as hot pot ingredients, and the boiling of the hot pot may result in the release of micro- and nanoplastics and harmful substances, potentially posing an ingestion risk. In this study, the release behaviors of micro- and nanoplastics and harmful substances including organic additives and heavy metals from the plastic coating were investigated by simulating the hot pot boiling process of crab sticks. Our results showed that 3.976 and 1.681 billion of micro-and nanoplastics/mL were released from red and green crab stick plastic coating during 2h of hot water soaking(≥95℃), among which the proportions of nanoplastics(<1μm) reached 99.99% and 99.96%, and those of microplastic fragments(1～5000μm) were only 0.004% and 0.037%. Based on Fourier transform infrared spectroscopy of virgin and boiled plastic coating, high-temperature boiling slightly altered the composition of the plastic coating(mainly as polyethylene) and led to the generation of a hydroxyl signal, indicating the occurrence of thermal oxidation. In addition, high-temperature boiling caused the formation and release of chain-scission products(low-molecular-weight binary carboxylic acid) and heavy metals(mainly Pb, Cr and As). Moreover, the concentration of heavy metals released from the whole crab stick(63.36 ng/L) was far greater than that of the individual plastic coating(0.99 ng/L), indicating the high risk of crab meat. The results indicate that crab stick plastic coating can greatly increase the intake of micro-and nanoplastics during hot pot boiling.
Uranium mining activities lead to the accumulation of uranium in surrounding aquatic environments, and its migration and transformation mechanisms are critical to ecological security. This study selected a typical uranium mining-affected river system and combined field investigations with laboratory simulation experiments to systematically reveal the synergistic control mechanisms of hydrodynamic disturbance, redox conditions(Eh), and colloidal transport on uranium migration. Field sampling uncovered the spatial distribution characteristics of uranium in the aqueous phase and sediments, identifying key areas such as fracture seepage zones as potential hotspots for remobilization. Short-term and long-term laboratory experiments demonstrated that the intensity of hydrodynamic disturbance directly regulates the partitioning of uranium between solid and liquid phases. Strong disturbance(120r/min) initially inhibited adsorption and promoted resuspension, while over the long term, it drove the transformation of solid-phase uranium into more active species. Mechanistic experiments further quantified key thresholds: within the near-natural weakly oxidizing to weakly reducing Eh window(approximately +80 to +100 mV), uranium release reached significant levels(49.7μg/L). Furthermore, sediment colloids derived from contaminated source areas exhibited higher yield and mobility(enrichment factor up to 3.2), acting as "high-speed carriers" for uranium. This study innovatively proposes a sequential model of uranium migration termed "disturbance initiation-Eh regulation-colloidal transport," clarifying the role of river sediments as a "dynamic source-sink transformer." The findings provide a crucial theoretical basis for precise risk early-warning and the development of remediation strategies in uranium-contaminated river areas.
Three novel modified kaolin-based algicides were prepared by combining kaolin with an organic flocculant, hydroxypropyl trimethyl ammonium chloride chitosan(HACC), and three types of allelochemicals. The influence of different preparation conditions on the algal removal efficiency was investigated. The results indicated that the optimal algal removal performance was achieved under the following conditions: a kaolin to HACC mass ratio of 15:1, a linoleic acid dosage of 5 mg/L, and a modified kaolin dosage of 60 mg/L. Under these optimal conditions, the removal rates of algae density, chlorophyll-a, and turbidity in water stably exceeded 95%. Scanning electron microscopy(SEM) results revealed that the prepared modified kaolin algicides exhibited significant particle agglomeration, with a substantial increase in the number of surface pores and specific surface area. Field experiments on the removal of natural cyanobacterial colonies demonstrated that HACC combined with linoleic acid-modified kaolin achieved a stable algal inhibition efficiency against field Microcystis colonies. It significantly reduced the activity of residual algae, and this state of activity, lower than normal, could persist for approximately one week.
Based on a multi-year field experiment, this study integrated ultraviolet-visible（UV-Vis） absorption spectroscopy and three-dimensional excitation-emission matrix（3D-EEM） fluorescence spectroscopy to characterize dissolved organic matter（DOM）, alongside sequential extraction to determine iron（Fe） speciation. These approaches were used to investigate the variations in DOM structural properties and Fe speciation, as well as their coupling relationships, in paddy soils under distinct fertilizer treatments: no fertilizer（CK）, phosphorus-potassium（PK）, nitrogen-potassium（NK）, and nitrogen-phosphorus-potassium（NPK）. Results indicated that fertilizer application increased soil DOM content（quantified as dissolved organic carbon, DOC） and its proportion relative to total organic carbon（DOC/SOC）. Under nutrient-limited conditions（PK and NK treatments）, DOC/SOC significantly increased by 115.73% and 64.30%, respectively, compared to the NPK treatment, reflecting a reduction in soil organic carbon（SOC） stability driven by nutrient limitations. Spectroscopic analyses revealed that fertilizer application increased DOM aromaticity(as indicated by SUVA254) but decreased the degree of humification（HIX） and fluorescence component intensities. Furthermore, nutrient limitation increased the content of exchangeable Fe, with the PK and NK treatments exhibiting 151.88% and 56.14% higher than the NPK treatment. Fertilizer application promoted the transformation of amorphous or poorly crystalline Fe to crystalline Fe, evidenced by a 20.95% ～ 53.93% decrease in Feox1（amorphous/poorly crystalline Fe） and a 12.63% ～ 53.44% increase in Feox2（crystalline Fe）. This indicates the crystallization and aging of iron oxides, a process notably absent under nutrient-limited conditions. Partial least squares path modeling（PLS-PM） revealed that fertilizer-induced changes in Fe speciation directly influenced DOM structural composition and indirectly affected DOM content via modifications to DOM structure. In summary, while fertilizer application mobilized a fraction of soil Fe, it also increased the crystallinity of iron（hydroxide） oxides. Long-term nutrient limitation induced by PK or NK fertilization significantly altered DOM and Fe speciation transformations, ultimately increasing DOM lability in paddy soils.
Arsenic(As) and antimony(Sb) commonly co-occur in mining-impacted river sediments, where redox transformations under anoxic conditions can substantially influence their mobility and ecological risk. Dissolved organic matter(DOM) has intrinsic photosensitive properties; however, it remains unclear whether DOM-derived photoelectrons can drive microbial As(V)/Sb(V) reduction. In this study, sediments from a mining-impacted river were investigated to evaluate photoelectron-microbe synergistic reduction by integrating field sampling, measurements of total concentrations and chemical speciation of As and Sb, characterization of DOM fluorescent components and photoelectrochemical responses, anaerobic microcosm incubations, and high-throughput sequencing. Results showed a clear gradient in both the As and Sb distribution, with downstream sediments exhibiting a higher proportion of reducible Sb. DOM composition shifted from humic-like to protein/tryptophan-like components, leading to enhanced photosensitivity and sustained photoelectron release. Anaerobic microcosm experiments showed that DOM-derived photoelectrons mediated 28.5% and 41.7% reduction of As(V) and Sb(V), respectively. Consistently, qPCR revealed strong stimulation of key reductase genes, with anrA, arsC, and arrA increased by 10～136-fold. The enrichment of electron-transporting and metal-reducing taxa forming a cooperative network that supported efficient photoelectron transfer and As(V)/Sb(V) reduction. Collectively, these results suggest that DOM-rich sediments can promote microbial As(V)/Sb(V) reduction via sustained photoelectron generation, revealing a previously unrecognized photoelectron-microbial synergistic mechanism for As/Sb transformation. The findings provide new insights into As and Sb biogeochemical cycling and have implications for pollution control in DOM-enriched environments.
This study employed Escherichia coli（E.coli） as a model organism to systematically elucidate the molecular response mechanisms induced by chloral hydrate（CH） exposure. The results revealed the total toxicity induced by CH increased with the increase of dose, with TELItotal rising from 1.87 to 2.36, with oxidative stress identified as the predominant mode of action. Differentially expressed genes were significantly enriched in biological processes including oxidative stress defense, DNA repair, and transcriptional regulation. At 1.87×105μg/L, stress perception and signaling pathways were primarily activated in the early stage of CH exposure, followed by sustained upregulation of defense and repair-related genes, while metabolism-related genes were inhibited. Notably, only 10% of co-expressed genes overlapped among different CH concentrations, indicating relatively independent regulatory patterns of stress responses. Furthermore, key genes such as uvrA, dnaK, and sodA were further identified, and the associated stress response constitute a core regulatory network centered on “defense-repair-homeostasis maintenance.” These results elucidate the molecular stress response characteristics induced by CH, and provide a theoretical basis for understanding its molecular toxicity mechanisms and conducting environmental risk assessment of CH.
A single-chamber microbial fuel cell(MFC) equipped with an activated carbon air cathode was constructed in this study, with tetracycline introduced as a stressor. The results showed that the degradation rate of tetracycline in the cathodic region was significantly higher than that in the control. To elucidate the degradation mechanisms under cathodic reduction conditions, analyses were conducted from the perspectives of microbial extracellular electron transfer(EET) and major carbon metabolic pathways. The findings revealed that, within the cathodic EET processes, the riboflavin-associated gene K11753(ribF) exhibited the highest abundance, with a 54% increase compared to the control, while the abundance of the pilus-related gene K02650(pilA) increased by 16%. These results indicate that riboflavin-mediated indirect electron transfer plays a prominent role in electron output in the MFC cathodic region. Furthermore, the abundances of key rate-limiting enzyme genes associated with central carbon metabolism(glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle) were generally elevated at the cathode, indicating an overall increase in carbon metabolic flux. Compared with the open-circuit control, the functional gene K01426(amiE), which is associated with the direct degradation of tetracycline, increased by 40% in the MFC. Its primary predicted host was Candidatus_Rokubacteria bacterium. Contribution analysis further indicated that this microorganism functions as a multifunctional electroactive bacterium, integrating electron transfer, metabolism, and degradation capabilities. In summary, this study preliminarily elucidates the principal EET pathways at the MFC cathode and demonstrates that the system can systematically activate microbial carbon metabolic networks, thereby synergistically enhancing tetracycline biodegradation. These findings provide a theoretical basis for the microbial electrochemical remediation of antibiotic-contaminated soils.
This study focused on six typical organophosphate esters （OPEs） frequently detected at high concentrations in Chinese environmental waters.We report the first evidence that all six OPEs binding to the zebrafish membrane receptor αvβ3.Among them,triethyl phosphate （TEP） exhibited the strongest binding capacity,showing significant competitive binding activity at environmentally relevant concentrations （≥0.18μg/L;P<0.05）.At an environmental concentration of 1μg/L,TEP exposed to zebrafish larvae significantly reduced swimming distance and speed （P<0.05）,altered locomotor activity patterns （including highly mobile,mobile,and immobile time;P<0.01）,decreased motor neuron ventral axon length and mean fluorescence intensity （P<0.05）,and downregulated the expression of neurodevelopmental marker genes （nkx2.2,gfap,elavl3,syn2a,gap43,and shha,P<0.05）.These results demonstrate that TEP induces locomotor behavioral abnormalities,impairs motor neuron development,and modulates neurodevelopmental marker gene expression,thereby revealing its neurodevelopmental toxicity at the individual,tissue,and molecular levels.Competitive inhibition experiments further confirmed that TEP exerts neurodevelopmental toxicity by binding to the membrane receptor αvβ3.Based on the dose-response relationship between TEP exposure and locomotor behavior in zebrafish,a benchmark dose lower limit （BMDL） at the 95%confidence interval was derived （0.11～0.32μg/L）,indicating that neurodevelopmental toxicity is a sensitive endpoint for TEP.This study advances the understanding of OPE-induced neurodevelopmental toxicity and its mechanism,providing a scientific basis for hazard identification and environmental safety management of these emerging pollutants.
A major industrial county in Shandong Province was selected as a case study to investigate the occurrence characteristics of per-and polyfluoroalkyl substances（PFASs） in multiple environmental media and the associated health risks posed to the surrounding population via exposure. Ultra-performance liquid chromatography-tandem mass was employed to determine the concentrations of 18 PFASs congeners in regional environmental samplings, including soil, outdoor dust, atmosphere, and drinking water. Correlation analysis and principal component analysis were utilized to identify the pollution sources of PFASs in different media, while the non-carcinogenic risks for surrounding populations were assessed by calculating the comprehensive risk entropy value. The results indicated that: PFASs were detected in all environmental media with detection rates ranging from 76% to 100%; The concentrations of Σ18PFASs in 50 soil samples, 17 outdoor dust samples, 15 ambient air samples, and 10 drinking water samples were 0.816～11.9 ng/g, 0.964～220 ng/g, 0.0223～8.35 ng/m3, and 1.44～18.0 ng/L, respectively, with average values of 3.47 ng/g, 34.2 ng/g, 0.594 ng/m3, and 6.40 ng/L. Among these PFASs, perfluorooctanoic acid（PFOA）, perfluorooctane sulfonate（PFOS）, along with their substitutes and precursors, were identified as the dominant components. PFASs pollution was primarily influenced by the production and emissions of fluorine-containing chemicals, fire-fighting foams, and electroplating industries. The non-carcinogenic risk of ΣPFASs exposure to different populations via hand-mouth ingestion of soil and outdoor dust, as well as and drinking water intake, was found to exceed the acceptable level, and children were found to be more sensitive to PFASs exposure. It was demonstrated that 18 PFASs congeners were widely present in the regional environmental media, predominantly derived from industrial production and emissions. The non-carcinogenic risks of ΣPFASs exposure to diverse populations through multiple pathways（e.g., soil, outdoor dust, and drinking water） were found to surpass the acceptable threshold, which warranted attention.
To evaluate the ecological toxicity effects of Clenbuterol(CLE), this study employed zebrafish(Danio rerio) embryos as a model to investigate the impacts of CLE exposure at different concentrations(0.2, 2.0, and 20 mg/L) on early development, neurobehavior, and oxidative stress status. By examining developmental indicators such as embryo mortality, hatching rate, and body length, it was found that CLE exposure had no significant effect on embryo mortality but significantly decreased the hatching rate(by 14.3%) and the frequency of spontaneous movement(by 31.9%) in the 20 mg/L treatment group, and also reduced body length. In the transgenic line Tg(hb9:EGFP), CLE exposure inhibited axonal outgrowth of spinal cord motor neurons, indicating adverse effects on neurodevelopment. Behavioral analysis demonstrated a significant reduction in locomotor activity in CLE-exposed larvae, suggesting impaired neurobehavioral function. Furthermore, biochemical analysis revealed that CLE exposure induced increase in reactive oxygen species(ROS) levels(by 117.9%), significantly increased the activities of superoxide dismutase(SOD) and catalase(CAT) by 78.6% and 64.4%, and elevated malondialdehyde(MDA) content in zebrafish, indicating its capacity to trigger an oxidative stress response. Transcriptomic profiling revealed that CLE disrupted focal adhesion-mediated cell-extracellular matrix interactions, interfered with neurotransmitter signaling pathways, and concurrently perturbed Wnt and MAPK signaling cascades. These molecular alterations were associated with the observed neurodevelopmental deficits. Collectively, the findings indicated that CLE impaired embryonic development and induced neurotoxicity in zebrafish through mechanisms involving oxidative stress and dysregulation of critical developmental signaling pathways, highlighting its potential ecological risk to aquatic vertebrates.
Under the strategic backdrop of synergistic advancement of the “dual carbon” goals and the “Digital China” initiative, clarifying the impact of green data centers on carbon emission efficiency holds significant practical importance. Based on panel data from 281 cities spanning 2008 to 2022, this study takes the “national green data center pilot program” policy as an entry point to explore the impact mechanisms, spatial effects, and empowering effects of different policies regarding green data centers on carbon emission efficiency. The findings are as follows: Green data centers can enhance carbon emission efficiency, with more pronounced effects in cities characterized by high economic development levels, strong information technology infrastructure, eastern or western geographic location, non-resource-based economic dominance, significant electricity consumption preference, and key environmental protection status. Regarding transmission mechanisms, green data centers improve carbon emission efficiency through three pathways: promoting green technology innovation, enhancing energy utilization efficiency, and supporting the development of the digital industry. In terms of policy empowerment, the low-carbon city pilot policy and the new energy demonstration city pilot policy play complementary effects in the impact of the national green data center pilot program on carbon emission efficiency, while the green finance pilot policy exhibits a substitutive effect. The smart city pilot policy shows no significant effect. Concerning spatial effects, green data centers exert a negative externality on the carbon emission efficiency of neighboring non-pilot cities, which is jointly moderated by spatial distance and economic linkage strength, displaying significant heterogeneity. The research conclusions provide important insights for optimizing the layout of green data centers and synergistically advancing the achievement of the “dual carbon” goals.
This study develops a spatialized life cycle assessment（LCA） framework to systematically investigate the spatial patterns of China's steel carbon footprint and its driving mechanisms at the provincial scale. The results show that nationwide, the average carbon footprint for producing 1 ton of crude steel was 2,721 kg CO2/FU, of which 58% originates from direct emissions in the production stage and 42% from upstream indirect emissions. The ESDA results indicate a positive spatial autocorrelation of provincial emissions, forming a “high-high” hotspot cluster centered on Shandong Province and a “low-low” coldspot cluster represented by Qinghai. The geographically weighted regression model reveals pronounced spatial heterogeneity in the effects of driving factors on both total emissions and emission intensity. Some key factors exhibit significantly different—and even opposite—directions and magnitudes across these two dimensions, leading to contrasting spatial patterns. These findings highlight the necessity of regionally differentiated and category-specific mitigation strategies to accelerate the green transition of China's steel industry.
In this study, we conducted an investigation at Weigang Cattle Farm in Sihong County, Jiangsu Province, using unmanned aerial vehicle(UAV)-based methane concentration measurements combined with the mass balance method to develop a methane flux estimation framework suitable for canopy-scale applications in cattle farm environments. Key methodological considerations were addressed, including plume characterization, background concentration selection, assessment of local meteorological and diffusion conditions, and optimization of sampling location and timing. The estimation results were validated against a ground-based observation system and a backward Lagrangian Stochastic(bLS) dispersion model. We further quantified the relative contributions of four typical emission sources within the farm: cattle barns, manure treatment area, lotus pond, and fishpond. The results showed that the UAV-based system effectively captured methane plumes downwind of the cattle farm, with estimated methane flux ranging from 35.06g/s to 53.71g/s. Under ideal observation conditions(wind speeds between 2.5m/s and 4.3m/s), the UAV-derived methane flux showed strong agreement with the total methane flux(57.68g/s) derived from the bLS model. The bLS model results further revealed that the manure treatment area, although accounted for only 7.8% of the total farm area, contributed 47% of the methane emission(27.54g/s), followed by cattle barns(23.2%, emissions 14.92g/s) and the lotus pond(25.9%, emissions 13.40g/s). This study provides a new technical approach for greenhouse gases flux assessment in small-scale composite ecosystems and suggests that current methane emission factors and source apportionments for cattle farms require further verification with additional empirical data.
Based on panel data from 280 Chinese cities over the period 2006～2021, this study systematically evaluates the spatiotemporal evolution, regional disparities, and driving factors of SGEPC by integrating a suite of spatial analysis methodologies, including the non-radial directional distance function(NDDF), Dagum Gini decomposition, spatial autocorrelation, and geographical detectors. The results indicate that China's SGEPC increased by 23.5% overall during the study period, presenting a spatial gradient pattern characterized by “eastern leadership and central-western catch-up”. The Yangtze River Delta urban cluster exhibited strong positive spatial spillover effects, forming a “high-high agglomeration” area; conversely, the Taiyuan and Guanzhong urban clusters remained mired in a “low-low agglomeration” predicament. Spatial variance decomposition shows that although inter-regional disparities narrowed, intra-regional differences consistently surpassed inter-regional ones, with hyper-variability density being the primary source of overall variance. This suggests that high-efficiency and low-efficiency cities are interspersed across the country, posing risks to the effectiveness of geographically partitioned governance strategies. Further geographical detector analysis reveals that the level of economic development and urbanization is the core driver of SGEPC. Moreover, emerging factors such as digital economic development and green technological innovation can generate a synergistic amplification effect of “1+1>2” when interacting with other socio-economic factors. These findings provide a scientific basis for constructing a regionally tailored, multi-measure environmental governance system.
In this study, the ISO 14040life cycle assessment framework was applied to develop a comprehensive greenhouse gas emission model and inventory encompassing the entire municipal solid waste（MSW） management chain—collection, transportation, and treatment. The carbon emissions of MSW management system in Chongqing's central urban area from 2011 to 2023 were quantified and key sensitivity parameters were identified. Results showed that net carbon emissions per ton of raw waste decreased significantly from 0.02t CO2/t MSW in 2011 to-0.53t CO2/t MSW in 2023, indicating a transition toward carbon negativity. The average carbon abatement associated with waste classification increased by 50%. Recycling of recyclable materials was emerged as the primary contributor to post-classification carbon benefits, with emission reductions rising from-0.28t CO2/t MSW in 2019 to-0.38t kg CO2/t MSW in 2023, representing 60.3% to 70.3% of the total absolute value of carbon emissions across all processes. Furthermore, using 2023 as the base year, scenario analyses under various policy configurations demonstrated that the "enhanced recycling" strategy alone delivers the highest individual carbon reduction benefit. However, the greatest overall reduction was achieved through integrated policy strategies, resulting in a net emission level of-0.65t CO2/t MSW. Based on these findings, this study proposes four policy recommendations: source reduction, process optimization, digital intelligence integration, and standardization enhancement—providing methodological insights and decision-support tools to accelerate the green and low-carbon transformation of Chongqing's MSW management system.
This paper constructs an evaluation index system for urban metabolic efficiency under the green low-carbon concept, and analyzes the spatiotemporal characteristics and influencing factors of urban metabolic efficiency across 282 cities in China by adopting the global undesirable outputs super-efficiency slacks-based measure(Super-SBM) model, kernel density estimation, spatial autocorrelation analysis and the spatial panel Durbin model(SPDM). The results show that China's urban metabolic efficiency has showed a sustained upward trend in general, while the inter-city gap has been widening with an obvious polarization phenomenon. High-value areas of urban metabolic efficiency are mainly concentrated in the eastern coastal and southern regions of China, whereas low-value areas are predominantly distributed in the inland areas of central and western China as well as the northern regions. The "T-shaped" spatial pattern of high-value areas along the Yangtze River and coasts has gradually emerged. Urban metabolic efficiency exhibits globally positive spatial autocorrelation, with the values ranging from 0.164 to 0.371. From a local spatial perspective, the spatial agglomeration pattern is dominated by low-low(LL) and low-high(LH) clusters, accounting for 65% of the total, while high-high(HH) and high-low(HL) clusters serve as supplements, accounting for 35%. At the national level, the spatial spillover effect coefficient of urban metabolic efficiency stands at 0.106, indicating that a 1% increase in the metabolic efficiency of local cities can drive a 0.106% improvement in that of neighboring areas. Regionally, the spatial spillover effect coefficient varies across different areas, showing a descending order of eastern region(0.123) >western region(0.087) >central region(0.068). Nationally, industrial structure upgrading, technological input, marketization level and environmental regulation intensity have a positive impact on the local urban metabolic efficiency, whereas urbanization and government intervention have negative effects on it. Industrial structure upgrading and marketization level generate positive spillover effects on the urban metabolic efficiency of neighboring regions, while government intervention and environmental regulation intensity bring about negative spillover effects. At the regional level, both the direct and spillover effects of influencing factors display notable regional heterogeneity.
Monthly, Started in 1981 Supervisor: China Association for Science and Technology Sponsor: Chinese Society For Environmental Sciences Editor-in-Chief: ZHANG Yuan-hang CN 11-2201/X ISNN 1000-6923
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