A heterotrophic nitrification and aerobic denitrification (HNAD) strain WN1 with significant tolerance against high ammonium concentrations was isolated from a reactor treating high-strength ammonium organic wastewater. Based on colony morphology and 16S rDNA analysis, it was identified as Corynebacterium glutamicum. The growth and metabolic characteristics of WN1 were studied under different initial ammonium concentrations of 500, 1000, 1500, 2000, 2500 and 3000mg/L, respectively. The results showed that strain WN1 could still grow well (48h, OD₆₀₀=3.264) at an initial ammonium concentration of 3000mg/L, corresponding to a free ammonia concentration of 590.2mg/L. As initial ammonium concentrations increased from 500 to 3000mg/L, the maximum ammonium conversion rate (R_m) of strain WN1increased from 15.93 to 43.29mg/(L·h). Additionally, the average conversion rates of ammonium and COD were 7.06~9.36mg/(L·h) and 95.63~199.13mg/(L·h), respectively. Furthermore, the Haldane model was used to characterize the growth and substrate degradation properties of strain WN1under different initial ammonium concentrations (R² = 0.99). Strain WN1had a maximum specific growth rate of u_max = 0.36h^-1, a maximum specific ammonium degradation rate of r_max = 6.45gN/(gDCW·d), and a maximum specific COD degradation rate of r_max = 122.85gCOD/(gDCW·d). The ammonium inhibition constant K_i of strain WN1was 3749.49mg/L, indicating greater resistance to high ammonium concentrations compared with other autotrophic or heterotrophic ammonium-oxidizing bacteria. The results suggest that strain WN1is promising for treating high-strength ammonium organic wastewater.

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.

Researches on lake methane (CH₄) production are of great significance for understanding the global CH₄ budget since lakes are important releasing sources for CH₄. In this study, sediment samples were firstly collected from Lake Taihu China then incubated in the laboratory with the purpose of investigating the temporal and spatial variations of the sediment methane production rates (MPR) in the lake. The environmental factors influencing the production rates were also analyzed. The results showed that MPR in sediments from Lake Taihu was 0.007~176.03µmol/(L·d). Higher MPR were found in the northwest bays and the eastern areas, while MPR in the open areas of Lake Taihu were relatively lower. The MPR in the sediments significantly varied from seasons, with the highest value of (42.85 ± 40.45) µmol/(L·d) in summer and the lowest of (5.26 ± 17.29) µmol/(L·d) in winter. The sediment MPR was positively correlated with the water temperature, the sediment water content, the porosity, the total nitrogen and the organic carbon. Differences of the temperature sensitivity (Q₁₀) for sediment MPR were found from different sampling sites. A significant negative logarithmic correlation between Q₁₀ and MPR was proofed. Microbial community analysis showed that hydrogenotrophic microorganisms dominated the methanogens in sediments of Lake Taihu during the summer. The copy number of the mcrA gene was significantly positively correlated with the sediment MPR. This study would provide important references to the studies of CH₄ production, emission and carbon cycle in Lake Taihu and the sediment MPR in other lakes.

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.

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.

A composite photocatalyst of bismuth oxybromide with oxygen vacancies covered by biochar (BC/OV-BiOBr, BOVB)was developed by hydrothermal method. Its photocatalytic performance was investigated with tetracycline (TC) as the target pollutant, and the catalytic effect was verified by dye pollutants. The results showed that 99.8% of tetracycline (TC) and 100% Rhodamine B(RhB) could be decomposed within 60min or 40min under visible light, of which degradation rates were 8.92 times and 9.82 times that of pure BiOBr, respectively. The degradation process of pollutants had strong resistance to pH change and low concentration co-existing ions. The results of phase characterization and photoelectrochemical performance test showed that the morphology was changed from flake to flower and the concentration of oxygen vacancies was increased after adding biochar, which were beneficial to improve the photoresponse and accelerate the charge transfer. Due to the synergistic effect between biochar and oxygen vacancies in driving the free radical chain reaction, the concentration of superoxide free radical (·O₂^-) in the system was increased, which was further transformed it into hydroxyl free radical (·OH), providing abundant strong oxidizing active species for pollutant degradation. In addition, good cyclic stability was certified by 5consecutive degradation experiments.

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.

To investigate the impact of phosphorus input on phosphorus output in the Three Gorges Reservoir Area, this study utilized the Net Anthropogenic Phosphorus Input (NAPI) model and the improved Export Coefficient Model (ECM) to analyze the spatiotemporal characteristics of phosphorus input and output from 2006 to 2021, as well as their response relationship. The results showed that the annual NAPI value initially increased and then decreased, with a peak in 2015. The distribution of NAPI values exhibited spatial clustering among counties, with phosphorus fertilizers contributing the most to NAPI, averaging 64.42% annually. Total phosphorus (TP) output fluctuated around 2500 tons per year with a slowly increasing trend, and the areas with high TP values shifted from the northeastern to the southwestern parts of the reservoir area. Dryland contributed the most to TP, with an annual average of 41.25%. There was a positive correlation between TP and NAPI, with the phosphorus input from human food and animal feed (P_im) having the greatest overall impact on TP, followed by non-food phosphorus input (P_nf) and phosphorus fertilizer input (P_fer). P_im was found to generate more TP per unit than P_nf and P_fer. The phosphorus output rate ranged from 1.18% to 2.26%, with an annual average of 1.78%. The proportion of P_im had the greatest influence on the phosphorus output rate, followed by the proportion of P_nf, with the output rate increasing as the proportions of P_im and P_nf increased. In contrast, the proportion of P_fer was negatively correlated with the phosphorus output rate. P_im posed the greatest threat to potential regional phosphorus pollution risks. This study provides scientific references for water environment management in the Three Gorges Reservoir Area.

The tolerance to cyanobacterial blooms and the need for ecological safety vary spatially across different areas of lake and reservoir water sources (e.g., intake areas, lake/reservoir zones, bay areas), which requires more precise selection and application of emergency response technologies. Currently, there is a wide range of emergency response technologies available for cyanobacterial blooms, but selecting efficient and safe technologies that are tailored to the specific scenarios of lake and reservoir water sources presents a technical challenge for emergency responders. This study first details the theoretical foundations of current emergency response technologies for cyanobacterial blooms, focusing on three main aspects: rapid algae-water separation, environmental factor regulation, and physiological growth inhibition, providing a theoretical basis for technology application. Secondly, based on spatial heterogeneity, the study categorizes different treatment areas within lake and reservoir water sources: interception, skimming, filtration, and clear water dispatching for highly sensitive intake areas; aeration, pressurized algae control, ultrasonic, flotation, and magnetic separation technologies for lake/reservoir zones; and flocculation, modified clay, chemical oxidation, photocatalytic oxidation, allelopathic plants, and microbial algae control for bay areas. Finally, the study comprehensively compares the technical requirements, advantages, duration of effectiveness, and application costs of these technologies in different water areas, providing a reference for the selection and development of emergency response technologies for cyanobacterial blooms in lake and reservoir water sources.

This study examined the vertical distribution of herbicide residues in 14 typical dryland soil profiles (0~100cm) from the black soil region of Northeast China. Residues from 57 different herbicides were measured across various soil depths to clarify their vertical distribution characteristics and influencing factors. The findings revealed that herbicide residue characteristics were primarily influenced by the application strategies under different land uses. Notably, nicosulfuron, a commonly used herbicide in cornfields, exhibited significantly higher residue levels in the 0~60cm soil layer compared to other herbicides. A negative correlation was observed between the herbicide's octanol-water partition coefficient (logK_ow) and its distribution ratio in the surface soil (0~20cm)(P<0.001), while a positive correlation was found between the herbicide's degradation period and its distribution ratio in the deep soil(80~100cm) (P<0.05). Additionally, soil pH was negatively correlated with herbicide residues in surface soils (P<0.05), and soil bulk density was negatively correlated with herbicide residues in deep soils (P<0.05). Summer rainfall was found to enhance the vertical migration of herbicides within the soil profile. These results provide crucial data and a scientific foundation for the mitigating, risk control and management of herbicide residues in the agricultural soils of China's black soil region.