In the surface environments, magnetite (Fe₃O₄) serves as an electron receptor and donor for microbial extracellular respiration, facilitating interspecies electron transfer as a means to promote the biodegradation of organic pollutants. It has gradually found application in the realm of water pollution remediation. The interplay between magnetite and the mineral-microbe interface assumes a profoundly pivotal role. However, the biodegradation mechanism of PAHs in sediments mediated by different morphologies of magnetite remains unclear. In this paper, two different morphologies of magnetite (micron Fe₃O₄ and nano Fe₃O₄) were prepared to investigate the effect of the magnetite on the biodegradation of PAHs in sediments. Under aerobic conditions, the addition of magnetite did not appreciably reduce the total content of PAHs and certain high-ring PAHs in the sediment. Nevertheless, the introduction of magnetite significantly diminished the levels of low-ring PAHs (naphthalene and phenanthrene) in the sediment. To further investigate the anaerobic biodegradation influence of magnetite on PAHs under varying redox conditions, with phenanthrene as the target pollutant, enrichment and cultivation experiments were conducted with the indigenous degrading microbial communities in the sediment. Two forms of magnetite were introduced under different redox conditions. The results revealed that the augmented treatment with magnetite or electron acceptors somewhat promoted anaerobic biodegradation. Under natural attenuation conditions, the independent addition of micron Fe₃O₄ significantly enhanced phenanthrene degradation, whereas the effect of nano Fe₃O₄ on phenanthrene degradation was more pronounced under sulfate and nitrate reducing conditions. The phenanthrene degradation rate constant under sulfate reducing condition was 1.39 times higher than that of the control treatment. Electron transfer system (ETS) activity demonstrated that the addition of Fe₃O₄ significantly enhances microbial respiration activity.Compared with the control, the ETS activity of the nano-Fe₃O₄ and the micro-Fe₃O₄ treatment increased by 441.7%~511.2% and 113.8%~141.1%, respectively. The microbial community structure indicated that the addition of Fe₃O₄ increased the abundance of aromatic compound-degrading bacteria such as Hydrogenophaga and Ignavibacterium, and relative to micron Fe₃O₄, nano Fe₃O₄ augments the abundance of PAH-degrading bacteria, Achromobacter and Ensifer. Furthermore, nano Fe₃O₄ may mediate intermicrobial electron transfer by releasing more Fe(II) and Fe(III). These findings contribute to a deeper comprehension of the pivotal role of magnetite in the biodegradation of organic pollutants, offering a potential approach for the remediation of contaminated sediments.

In this study, a full-scale CANON system was constructed to treat high ammonia nitrogen iron oxide wastewater following physicochemical pretreatment. Over the course of 165days of continuous operation, the CANON system demonstrated excellent stability and shock resistance, achieving ammonia and total nitrogen removal efficiencies (TNRE) of 90% and 80%, respectively.Spearman correlation analysis and SHAP feature importance analysis were employed to elucidate the impact of water quality and environmental parameters on TNRE. Microbial community profiling unveiled substantial shifts in microbial population structures within the system, marked by the transition of the dominant anammox bacteria from Candidatus Anammoxoglobus to Candidatus Kuenenia, accounting for a relative abundance of 13.22%. Nitrosomonas was identified as the predominant ammonium-oxidizing bacteria with a relative abundance of 1.27%. Additionally, a machine learning model based on XGBoost was developed, which achieved a predictive accuracy of over 99.9% for TNRE, with a prediction precision of 98% for new data points in practical applications. This research provides valuable empirical insights into the engineering application and intelligent development of anammox processes.

Because of singlet oxygen (¹O₂)’s strong oxidation capability and environmental friendliness, understanding the mechanism of chlorine-mediated ¹O₂ generation in electrochemical processes can enhance wastewater treatment efficiency and minimize the side effects of active chlorine. Thus, electrochemical tests and treatment of Rhodamine B (RhB) simulated wastewater were used to assess the performance of Ir-Ta/Ti and Pt/Ti electrodes. The effects of different conditions (Cl^- concentration, chlorine evolution activity of electrodes, H₂O₂ addition, O₂ aeration) on electrochemical ¹O₂ generation were also explored. The results demonstrated that the ¹O₂-dominated electrochemical system can remove over 96% of RhB and shorten degradation pathways.Efficient ¹O₂ production depends on balancing hypochlorite (ClO^-) and hydroperoxyl (HO²_-) in the system, as an excess of either suppresses ¹O₂ generation. This study provides a theoretical framework for enhancing ¹O₂ generation under various conditions and the targeted preparation and modification of electrodes.

We established an assessment framework for coastal ecological resilience and conducted a regional evaluation in the area of Shenzhen as a case study. The STIRPAT model was employed to quantify the socioeconomic factors affecting coastal ecological resilience and identify key influencing factors and the extent of their impact. Strategies for coastal zone protection and restoration were also proposed. The results showed that, in 2021, the Shenzhen's coastal ecological resilience score ranged from 8.97 to 92.12, indicating a distinct spatial difference between the eastern and western parts, with a higher ecological resilience in the former. The spatial pattern of coastal ecological resilience was closely associated with the underlying geographical characteristics and urban developmental features of the area. The level of regional affluence was identified as a major negative factor impacting the resilience, followed by other factors such as reclaimed land area, environmental pollution, and population density. Conversely, a reduction in water consumption per unit of GDP showed a positive effect on coastal ecological resilience, suggesting that technological innovation and high-quality economic development can significantly enhance coastal ecological resilience. The results of this study provide a new method for studying ecological resilience in high-density urban coastal zones and a scientific basis for coastal zone management.

Winter wheat is the main cereal crop in Northern China, and excessive nitrogen (N) fertilization and irrigation are employed in recent years to ensure a high grain yield. A high amount of N was lost via leaching, which exacerbated the risk of non-point source pollution and further increased the resource waste. It is highly necessary to clarify the characteristics and influencing factors of N leaching loss during the winter wheat season in the region. The literature on N leaching loss from the winter wheat production in Northern China, published from 2000 to 2023 was screened, and linear, multiple-factor regression models, as well as random forest and XGBoost models were established in the study. The research showed that the N leaching during the winter wheat season was mainly affected by the fertilizer rate and irrigation water, as well as soil properties (pH, clay and sand content), and was effectively inhibited by crop straw incorporation. Multiple variable combinations were constructed based on the results of importance analysis and stepwise regression. Grid search method, Bayesian and the combination of Bayesian and Early stopping were used to optimize the model parameters. The models constructed through Random Forest, based on all influential variables and based on the influential variables screened by stepwise, had the R² of 0.628 and 0.708, respectively, and the R² for the corresponding models constructed through XGBoost were 0.745 and 0.722, respectively. This indicates that the prediction effects of N leaching based on Random Forest and XGBoost were much better than the linear and multiple-factor regression models. The influence of multiple factors on N leaching was comprehensively considered in the machine learning models, and the effects of prediction were better when choosing the influential variables screened by empirical statistical methods as independent variables. The results of this study can provide technical support for reducing the N leaching in the winter wheat production in Northern China.

This paper combined multi-source data to develop the identification approach of VOCs high-emission areas during ozone pollution season (from May to September). At the same time, the spatial distribution pattern and long-term change trend of VOCs during the ozone pollution season in Beijing from 2005 to 2023 was examined and discussed based on satellite-derived HCHO column concentration. The results showed that the concentration of VOCs in Beijing is at a high level within the Beijing-Tianjin-Hebei region, and its distribution was significantly affected by human activities. The total amount of HCHO in the areas of anthropogenic sources dominated was 3.4times of that of natural sources dominated. The high emission areas of anthropogenic sources mostly appeared in the northern, central eastern, and southwestern parts of the urban area of Beijing City.Approximately 61% of the areas were sources of industrial production process and solvent usage, and mainly distributed outside the Fifth Ring Road. Approximately 39% of them were sources of automobile maintenance, logistics warehousing etc., and mainly distributed along highways. This identification method has improved the effectiveness of ozone pollution prevention and control work in the summer of 2023, offering technical support for locating key regulatory objects and areas. From the perspective of interannual variations, the column concentration of VOCs in Beijing showed an increasing trend from 2005 to 2018, with an increase of about 26% (after correction of temperature), while it showed a downward trend from 2018 to 2023, with a decrease of about 11%, reflecting the effectiveness of VOCs emission control in recent years.

To alleviate the harmful effects of salinization on soil micro-ecological environments, this study investigates the restorative effects of a dual microbial system on saline-alkaline soil. The experiment used the tomato variety 'Zhongshu No. 4'(Lycopersicon esculentum L.) as the test plant and tested arbuscular mycorrhizal fungi (AMF) and Bacillus subtilis as inoculants. Inoculations were carried out using pot culture and root drenching methods, with saline-alkaline solutions at concentrations of 15mmol/L (SA₁), 75mmol/L (SA₂), and 150mmol/L (SA₃), to assess the effects of exogenous AMF and B. subtilis on the soil micro-ecological environment under saline-alkaline stress. Results showed that both AMF+B. subtilis sterilisation solution (Gm) and AMF steriliser+B. subtilis (B) moderately improved the saline-alkaline soil conditions. However, the dual treatment (Gm+B)demonstrated the most pronounced remediation effect. Under the dual inoculation, plant height increased significantly, by 57.52%compared to the blank control (CK₁) and by 58.04% compared to the inactivated inoculant control (CK₂). In the Gm+B group, soil organic matter increased by a maximum of 47.15% compared to CK₁, exceeding the growth observed in the Gm and B treatments alone. Significant increases in soil total nitrogen (N), available phosphorus (P), and available potassium (K) were observed, with improvements of 38.85% (SA₂+Gm+B), 465.20% (SA₁+Gm+B), and 157.75% (SA₃+Gm+B), respectively. Soil enzyme activities, including urease, sucrase, and catalase, were markedly enhanced under dual treatment, with increases of 63.64% (SA₂+Gm+B),209.63% (SA₃+Gm+B), and 45.26% (SA₃+Gm+B), respectively. Soil bacterial, fungal, and actinomycete populations increased to 1.93, 1.25, and 4.37times those of CK₁under SA₂+Gm+B and SA₃+Gm+B, indicating a substantial improvement in the rhizosphere microbial community structure. The synergistic interaction of AMF and B. subtilis reduced soil pH and electrical conductivity while significantly increasing soil moisture content. N, P, and K levels showed an upward trend, and AMF colonization rates were enhanced, effectively mitigating the negative effects of saline-alkaline soil on enzyme activities and promoting root and stem development. Therefore, the AMF-B. subtilis dual microbial system demonstrates strong potential for effective ecological restoration of saline-alkaline soil microenvironments.

Based on the unique hydrodynamic and environmental conditions of stormwater artificial recharge, a series of one-dimensional seepage simulation experiments were conducted. The migration and deposition characteristics of clogging microorganisms within porous media under varying seepage conditions, such as different saturation levels, pH environments, ionic strengths, and recharge rates were systematically analyzed and the development of bioclogging within porous media under different seepage conditions was clarified. DLVO theory was used to reveal the dominant forces during microbial migration under different pH environments and ionic strengths. The results showed that the migration of microorganisms slowed down as saturation decreased, pH lowered, ionic strength of the recharge water increased, or recharge flow rate decreased. Consequently, deposition on the medium increased, while interlayer deposition became more uniform, promoting the formation of bioclogging within the medium. Changes in saturation, pH, or ionic strength had minimal effect on microbial migration when saturation was between 60% and 80%, pH was between 7.5 and 8.5, or ionic strength was between 1and 5mmol/L. Under unsaturated conditions, the impact of recharge rate variations on microbial migration and deposition was weakened when the recharge rate was within the range of 0.5to 1mL/min. Under different pH environments and ionic strengths, the dominant forces during microbial migration in saturated and unsaturated media were electrostatic forces and capillary forces, respectively.

This study used a meta-analysis approach to examine the distribution of three polycyclic aromatic hydrocarbons (Phe, Pyr and BbF) in the surface water of the world's seas as well as the factors that influence them. According to the findings, the Pacific Ocean had significantly greater concentrations of Phe, Pyr and BbF (16.885, 15.787, and 0.642ng/L) than the other oceans. These concentrations were also significantly linked with salinity, temperature, latitude, distance from coast, and chlorophyll. According to the findings, energy consumption and oceanic PAHs had a substantial and positive correlation (P<0.05). The distribution pattern of PAHs in the world's oceans is shown by this study, which offers a scientific foundation for the development of practical methods for the prevention and management of marine pollution.

We conducted a seasonal survey on phytoplankton and environmental factors in Yilong Lake from summer, 2020 to spring,2021 to uncover the seasonal pattern of phytoplankton community structure and biomass, and further identify the driving forces of bottom-up and zooplankton’s top-down effect in mediating phytoplankton variations through multivariate analysis. The results showed that the phytoplankton’s biomass in Yilong Lake ranged from 7.12mg/L to 66.07mg/L, with the highest value in September and the lowest value in December. The phytoplankton community was dominated by Cyanophyta, which contributed to 42.91% to 95.67% of total phytoplankton biomass. Raphidiopsis raciborskii, absolutely predominated during the investigation period(23.43%~84.30%), reflecting its strong competitive advantages. The ANOSIM and Kruskal-Wallis analyses indicated that there existed significant temporal fluctuation in phytoplankton community structure and biomass(P<0.05). The Spearman’s correlation analysis revealed that the biomass of phytoplankton, Cyanophyta and R. raciborskii were all positively related to total phosphorus(P<0.05), total nitrogen and water temperature and negatively related to transparency and ammonia nitrogen(P<0.05), but had no significant correlation with zooplankton biomass(P>0.05). The RDA results showed that total phosphorus, total nitrogen, silicate, water temperature and water depth were among the significant factors in driving phytoplankton community in Yilong Lake. The results of variation partitioning further revealed that the bottom-up effect (water temperature, nutrients and water depth) and top-down effect (zooplankton community) accounted for 20.30% and 0.20% of the total variance independently with a shared portion of 5.80%. Therefore, the bottom-up effect had a greater impact on variations in phytoplankton community than the top-down effect by zooplankton in Yilong Lake. This may be because zooplankton in Yilong Lake had small mean body length (ZB/ZA:0.0019±0.0018) and relatively low biomass (0.56±0.39mg/L), and thus resulting in the weak grazing pressure on algae (ZB/PB:0.0303±0.0271). Our results will provide scientific data for the ecological assessment and integrated watershed management of Yilong Lake.