The discovery of complete ammonia-oxidizing bacteria（comammox）provided a novel direction for improving nitrification efficiency in wastewater treatment systems. The potential of their metabolic pathways and functional genes for efficient nitrogen an d carbon removal from wastewater was demonstrated. However, strategies to achieve robust comammox enrichment remained controversial. Further investigations were required to characterize the specific contributions to ammonia removal and nitrous oxide（N₂O）production during the nitrification process. The technical strategies for efficient comammox enrichment and the impacts of key factors including environmental substrate concentration, dissolved oxygen, operational processes, and temperature on the selective enrichment of comammox were summarized. Chlorate was employed as a specific inhibitor targeting comammox in combination with 1-octyne to construct a dual-inhibitor experimental system, which was capable of clarifying the nitrification contribution and N₂O emission potential of comammox in wastewater treatment systems.

The UV/O₃/PS process was used for the degradation experiments of chloramphenicol, the degradation performance of the combined UV/O₃/PS process, UV/PS, O₃/PS and UV/O₃ processes was investigated, the contribution of major active free radicals to CAP degradation was analyzed for the reaction system, the effects of PS concentration, O₃ concentration, pH, and the common inorganic anions and natural organics on the degradation were examined respectively, the degradation pathway of CAP and the formation potential of disinfection by-products were clarified, also the calculation of energy consumption for the UV/O₃/PS process was discussed. The results showed that the CAP removal by the combined UV/O₃/PS process was 90.41% at 60min. ¹O₂, HO· and SO₄⋅^- were the three main active species in the reaction system, and their contributions to CAP degradation were 53.85%, 25.64% and 12.82% in turn. the increase of PS and O₃ concentrations favored the degradation of CAP, and alkaline conditions could promote the degradation of CAP, co-existing Cl^-, HCO₃^- and humic acid inhibited the degradation of CAP. the degradation mechanism of CAP by the UV/O₃/PS system mainly involved the hydroxylation, amino oxidation and C-N bond breaking or something. The formation potential of trichloromethane and trichloroacetonitrile was significantly increased through CAP pre-oxidation treatment, the formation potential for trichloromethane increased from 30.35µg/L to 48.08µg/L and that of trichloroacetonitrile from 12.31µg/L to 20.97µg/L. Energy consumption evaluation showed that the UV/O₃/PS process has a better overall efficiency.

The effects of three different influent strategies on the protein content of extracellular polymeric substances（EPS）were investigated to assess their impact on sludge retention capacity of the CANON process. R1was operated under conventional influent strategy as the control group, while R2 and R3 were subjected to different variable influent strategies. After 90 days of operation, the SVI values in R1, R2, and R3 were 62.93, 53.10, and 57.59mL/g respectively indicating that the variable influent strategies could improve sludge settleability. The PN/PS ratios were significantly higher in R2（8.21）and R3（7.61）compared to R1（5.56）. Three-dimensional fluorescence analysis revealed that the proportion of aromatic proteins in TB-EPS was highest in R2（32.47%）, much higher than in R1（11.58%）and R3（10.5%）. This indicated that the variable influent strategy promoted the formation of aromatic proteins in TB-EPS, enhancing the hydrophobicity of the sludge and improving settleability. The specific anaerobic ammonium oxidation activity（SAA）increased to 4.03, 4.68 and 4.36mg N/（g VSS· h）in R1, R2, and R3, respectively. Notably, the SAA in R2 and R3 exceeded that of the seed sludge, indicating the successful formation of mature CANON granular sludge. Although microbial activity in R2 and R3 was initially inhibited by loading fluctuations during early operation, the microbial communities gradually adapted to environmental fluctuations and regained stable metabolic activity, successfully operating the CANON process on day 54 and day 51, respectively. Total nitrogen removal efficiencies reached approximately 72.54%, 70.14%, and 73.75% in R1, R2 and R3 by day 90, demonstrating effective nitrogen removal performance.

Poyang Lake is characterized by significant water level fluctuations, leading to complex transformation processes among precipitation, soil water, and groundwater. Due to the limitations of intricate wetland conditions and traditional monitoring methods, it is challenging to conduct quantitative studies on soil water movement and its interaction with groundwater. In this study, three vegetation communities at different elevations in Poyang Lake were investigated to analyze the isotopic composition of precipitation, lake water, groundwater, and soil water（0~80cm）. The characteristics of wetland soil water movement were examined across various hydrological periods. The results showed that the slope of the soil evaporation line（SEL）in the Artemisia capillaris community（5.91）was significantly lower than that of the local meteoric water line（LMWL, 7.60）. The lc-excess values of soil water in 0~60cm layer were negative, indicating strong evaporation, with a maximum impact depth of 60 cm. The slopes of the SEL in the Phragmites australis and Carex cinerascens communities（6.70 and 6.75, respectively）were slightly lower than the LMWL, and the lc-excess values of soil water were close to 0, indicating minimal evaporation. Regarding soil water movement, the δ¹⁸O values of soil water in the A. capillaris community increased with depth during spring（May）and summer（June to August）, indicating piston-flow dominated transport. During autumn（September and October）, soil water δ¹⁸O values became enriched and decreased with depth, indicating the dominant influence of evaporation. Furthermore, the soil water δ¹⁸O values in the A. capillaria community were significantly enriched compared to groundwater isotopes. No depleted isotope signals or evidence of groundwater supply were detected in the soil water, even when the groundwater table was at its shallowest（1.92m）. These results suggest that vertical hydrological connectivity between root-zone soil water and groundwater was blocked. In contrast, soil water movement in the P. australis and C. cinerascens communities was significantly influenced by groundwater level fluctuations. During the groundwater level rise period（April and May）, shallow soil water（0~40cm）in these two communities primarily originated from atmospheric precipitation, while deep soil water（40~80cm）was replenished by capillary rise of groundwater. Groundwater contributed more than 50% to the replenishment of root-zone soil water. During the shallow groundwater table period（June and August）, frequent exchanges occurred between soil water and groundwater in the P. australis community. In the groundwater table decline period（September and October）, the P. australis and C. cinerascens communities exhibited non-uniform soil water flow processes, characterized by noticeable preferential flow.

Using the Gansu section of the Yellow River Basin as the research object, Fragstats 3.3 software and Pearson correlation analysis method were used to calculate the landscape pattern index of the river buffer zone, analyze the correlation between water quality and landscape pattern indicators, and investigate the factors influencing the water quality of the Yellow River’s main stream and tributaries in Gansu Province. The data included the land use data with the resolution of 30m in 2020, water quality monitoring data, and socio-economic data from 2018 to 2021. The results indicated that:（1）From 2018 to 2021, the water quality of the main stream and tributaries of the Yellow River in Gansu Province were improving, except the Taohe River, where the concentration of water quality indicators was in the increasing trend；however, TN at more than 80% of monitoring sites remained above Class V water quality standards, with significant nitrogen pollution persisting in the Weihe River, Jinghe River, and Zhuanglang River. High concentrations of TN and NH₄⁺-N were mainly distributed in the central and eastern parts of the basin, TP levels were elevated across most areas, and COD was dispersed, with hotspots concentrated in parts of Lanzhou City and central Linxia Hui Autonomous Prefecture.（2）A significant correlation was observed between landscape patterns and water quality indicators. Higher aggregation and connectivity of landscape patches were associated with better water quality, whereas higher levels of fragmentation and dispersion increased the risk of water pollution.（3）Water quality indicators exhibited strong spatial heterogeneity. The driving factor analysis revealed that NH₄⁺-N, TP, permanganate index, and COD were primarily influenced by rural activities, while TN and DO were mainly affected by urban living and industrial production.

The Dongjiang River Basin was chosen as the study area to compare the nitrogen concentrations and isotopes in the river with different land uses, so as to provide a better understanding and evidence for impacts of urbanization on active nitrogen turnover. In this study, the distinct characteristics of nitrogen concentrations and isotopes were found in urbanized rivers compared to rivers with other land uses. Firstly, the nitrogen concentrations in urbanized rivers were gradually increased due to urbanization and nitrate has become a main nitrogen speciation. Secondly, based on the isotope Rayleigh fractionation model, it was found that the nitrification potential in urbanized river channels was enhanced and about 25.8% of nitrate nitrogen came from nitrification in situ. In addition, a positive correlation between ln（NO₃^--N）and δ¹⁵N-NO₃^- was recorded in urbanized rivers. Moreover, Δδ¹⁵N/Δδ¹⁸O in the dry and wet seasons were –2 and -6, respectively, indicating that the denitrification potential was weakened to provide evidence for nitrate accumulation in urbanized river channels. Likewise, a weak correlation between δ¹⁵N-PN and δ¹⁵N-NH₄⁺ was also recorded in urbanized rivers, and the ¹⁵N enrichment factor of nitrate assimilation also differed from the theoretical value, indicating a weak assimilation of ammonia and nitrate nitrogen. Finally, more input pathways and less sink processes of nitrogen in urbanized rivers have become a key mechanism for elevated riverine nitrogen concentrations in the lower reaches of Dongjiang river.

To elucidate the potential ecological risks of carbon dots, a novel nanomaterial, this study investigated the physiological responses and underlying mechanisms of the freshwater microalgae Euglena gracilis following exposure to pristine carbon dots（CDs）and Cu-N-doped carbon dots（Cu-CDs）. The results demonstrated that both types of carbon dots initially promoted but subsequently inhibited the growth of E. gracilis over time. Compared to CDs, Cu-CDs exerted a more pronounced impact on key physiological processes, including photosynthesis and antioxidant defense. Exposure to 1mg/L and 10mg/L Cu-CDs resulted in the accumulation of photosynthetic pigments and a decline in photosystem II activity, whereas a significant change in photosynthetic pigment content was observed only at 10mg/L in the CDs-exposed group. The maximum inhibition rates of superoxide dismutase activity induced by CDs and Cu-CDs were 62.52% and 78.35%, respectively. Metabolomics analysis further confirmed that Cu-CDs triggered a stronger metabolic disturbances, with the most notable alterations observed in lipid metabolism pathways, indicating compromised membrane stability of E. gracilis. Disruptions in amino acid and photosynthetic metabolism pathways were primarily attributed to oxidative stress. Additionally, both CDs and Cu-CDs affected energy metabolism by altering in alanine, aspartate, and glutamate metabolism, as well as glycolysis/gluconeogenesis pathways. Overall, the impairment of photosynthetic and antioxidant system may represent the primary toxic mechanisms of carbon dots in E. gracilis.

We chose a petrochemical park in Beijing-Tianjin-Hebei as the research target, and five representative sites were selected for sampling and analysis. 85 volatile organic compounds（VOCs）were detected and their impacts on the environment and health were evaluated. The results showed that the concentration of total volatile organic compounds（TVOCs）were 546.0~4472.2µg/m³, in which alkanes and alkenes were the dominant group, followed by aromatics and halocarbons. Compared with the diurnal variation of VOCs components at each site, the time of peak and valley values appearing were different, and the typical species were different. Additionally, OFP in the synthetic rubber area was the richest（13239.8µg/m³）. The contribution of alkenes to OFP was the highest（62.8%~90.5%）, followed by alkanes（3.8%~34.8%）and aromatics（2.2%~22.1%）. Otherwise, only the synthetic rubber area was polluted by odor, 1,3-butadiene（0.68）and n-hexane（0.30）were the main VOCs species that produced odor. Moreover, the health risk associated with each site was assessed by the US EPA method, indicating that the non-cancer risk of synthetic rubber and cancer risk of oil refining were higher than those of other sites.

This study conducted a comprehensive life cycle assessment of the carbon footprint associated with the solidification/stabilization combined with barrier backfilling（SSB）technology through a typical heavy metal-contaminated site case in South China. Using the emission factor method and life cycle impact assessment approach, we quantified the environmental impacts across the entire remediation process. The results revealed that the SSB technology exhibited a carbon emission intensity of 0.190t CO₂/m³ contaminated soil. The most important carbon emission unit processes were primary treatment（33.7%）, site construction（32.7%）, and barrier backfilling（31.9%）. Material production emerged as the principal emission source, with concrete manufacturing contributing 51.9% and solidification/stabilization reagents accounting for 33.4% of total emissions. The comprehensive environmental impact score of this case reached 84.3kPt. The implementation process of risk control exerted the most significant human health impacts, which were primarily contributed by the formation of fine particulate matter during construction activities and the global warming potential.

To predict the long-term response of soil and surface water chemistry after the reduction in acid deposition, a dynamic MAGIC model combined with long-term monitoring data was conducted on a subtropical forest in Tieshanping, Chongqing, Southwest China. Under the “actual emission reduction” scenario based on China's “14th Five-Year Plan”（where the sulfur dioxide（SO₂）emissions remained at the 2020 level, and the nitrogen oxides（NO_x）and ammonia（NH₃）emissions were reduced by over 10%and 8%, respectively, by 2025）, the simulation results indicated that sulfate（SO₄²⁻）concentrations in soil water（S1and S2）and surface water（SW）initially increased, and stabilized after 2028 until 2050. The average SO₄²⁻ concentrations in S1, S2 and SW water from 2021 to 2050 were 1426, 1414, and 938µeq/L, respectively, which were still above the 1980levels. The decline of SO₄²⁻ concentrations in surface water was delayed by approximately 23 years. Soil water nitrate（NO₃⁻）concentrations showed a declining trend by 2050, but it remained above the threshold（443µeq/L）, whereas surface water NO₃⁻ concentrations had decreased below its threshold（411µeq/L）. The decline of NO₃⁻ concentrations in surface water was lagged approximately 13 years, compared to it in throughfall. Additionally, the concentrations of base cation（calcium, Ca²⁺）in both soil and surface water increased. The pH and Acid Neutralizing Capacity（ANC）in soil and surface water remained below their acidification thresholds. The acidification recovery showed a lag effect. The strong acidic anions in soil and surface water will decrease below their thresholds, pH will increase, and ANC will increase above 0µeq/L, when the stricter emission control policies were implemented, for example the SO₂ emissions decrease to 80% of 2021l evels by 2030 and 70% of 2021 levels by 2050, and the NH₃ emissions, NO_x emissions, and Ca²⁺ deposition decrease to 60% of 2021 levels by 2030 and 40% of 2021 levels by 2050. Moreover, further global temperature increases showed insignificant impact on the major strong acidic anions and acidification indicators in the highly acidic soils and surface waters of the subtropical forest.