This study mainly compared the emission characteristics of N₂O in two typical wastewater treatment processes, SBR and AAO, and analyzed the mechanisms that cause the differences.. The results indicated that according to the total nitrogen removal efficiency of the SBR process, the N₂O emission factor (EF) was 2.36%, which is 1.92 times higher than that of the AAO process. The aerobic phase was identified as the primary stage for N₂O production in both processes, accounting for over 90% of the total N₂O generated. Compared to the continuously AAO process, the sequencing SBR process exhibited a longer duration of low DO conditions. A sudden increase in NH₄⁺-N concentration o and a high accumulation of NO₂^--N ccurred at the onset of the aerobic phase. Analysis of the microbial community structure and enzyme activity revealed that SBR process had a higher ratio of ammonia-oxidizing bacteria (AOB) to nitrite-oxidizing bacteria (NOB) and a higher nitrite reductase (NOR) activity, which were 1.7 and 1.4 times those of the AAO process, respectively. This further facilitated the production of more N₂O through the AOB-mediated nitrification-denitrification pathway during the aerobic phase, which is the intrinsic mechanism for the high N₂O emission factor of the SBR process.

By using Eisenia fetida as the test object, the growth and reproduction, cytochrome P450 (CYP) sub-enzymes activity, and small molecule metabolites were measured to investigate the metabolic toxicity of polyethylene microplastics with different particle sizes (small, 30~50µm; large, 125µm) at different concentrations (0.5, 2.5, 10, 20g/kg). The results showed that small particles of polyethylene were more likely to retain and accumulate in earthworms, and their harm to earthworms were greater. And large particle polyethylene microplastics could inhibit the reproduction of earthworms to some extent. The top twelve most important metabolites identified by metabolomics responded differently under the stress of different sizes of polyethylene, and the particle size of polyethylene had a significant effect on the toxic effect. The stress of small-size polyethylene with low concentrations (0.5, 2.5g/kg) had no significant effect on the CYP2B6 and CYP3A4 activities and the concentrations of important metabolites in earthworms; under the stress of small-size polyethylene with high concentrations (10, 20g/kg), the levels in seven important metabolites (L-formylkynurenine, androstanedione, androstenedione, docosapentaenoic acid, (5Z, 8Z, 14Z) -11, 12-dihydroxyicosa-5, 8, 14-dienoic acid (11, 12-DHET), inositol, and all-trans-retinoic acid) significantly increased by 20.5% to 70.2% compared to the control. Small-size polyethylene could cause the inflammation and neuro-metabolic disorders in earthworms, and damage their osmotic regulation metabolism. The significant induction of CYP2B6 and CY2C9 activity revealed that earthworms had certain detoxification functions. Under the stress of large-size polyethylene with the concentration of 0.5~20g/kg, no significant change in the activities of CYP2B6 and CYP3A4 in earthworms in comparison to the control was observed. However, the levels in majority of important metabolites, including L-formylkynurenine, androstanedione, androstenedione, adenosine 3'-phosphate, inosine, and xanthine, were all significantly lower than the control by 20.0% to 77.3%, which suppressed the hormone production of the earthworms, thus affecting their reproduction and metabolism.

In this study, the pollution of direct and leakage in Shiwuli River was analyzed by combining anionic surfactant sodium dodecyl benzene sulfonate (SDBS) and dissolved organic matter (DOM) traceability methods, and the correlation and difference of each index were studied by Pearson correlation analysis method. The results showed that the content of SDBS in untreated domestic sewage was high (522~668µg/L), which was easily affected by industrial washing wastewater when characterizing the pollution situation. DOM is characterized by high percentage of CHOS compounds (83%~84%), protein + lipid components (80%~81%), high hydrogen-carbon ratio (H/C=1.6) and low-carbon nominal oxidation state (NOSC=-1) in untreated domestic sewage. Combining the advantages of SDBS and DOM traceability can effectively eliminate interference factors and make the characterization of river domestic sewage pollution more reliable. This study can provide new ideas and technical support for the analysis and traceability of the direct and leakage of domestic sewage pollution in rivers.

As a kind of complex polar organic compounds commonly existing in the atmosphere, dissolved organic carbon (DOC) in precipitation has extensive and far-reaching influences on regional ambient air quality, global climate change and carbon cycle process, and has become one of the hot spots in current global change research. This article systematically summarized the research progress on atmospheric precipitation DOC in recent decades both domestically and internationally from three aspects: the abundance and bioavailability of DOC in atmospheric precipitation, the spatial and temporal distribution characteristics and influencing factors of DOC concentration and wet deposition flux in precipitation, and the ecological and environmental effects of DOC wet deposition. In the end of the article, the future development direction was discussed. The results indicated that the chemical composition of precipitation DOC is exceptionally complex, mainly composed of low molecular weight organic acids, amino acids and urea, etc. with high bioavailability. There were significant spatiotemporal differences in precipitation DOC concentration and wet deposition flux among different areas, which were mainly controlled by emission sources, emission intensity, and complex weather conditions. The DOC in the atmosphere could affect the properties of aerosols and precipitation (acid rain), and DOC settling on the surface of snow and ice could accelerate the melting of glaciers. At the same time, the input of DOC brought by wet deposition can enrich the organic carbon levels on the surface of seawater. Active DOC can promote the improvement of secondary productivity in marine ecosystem, while refractory DOC could contribute to the refractory dissolved organic carbon pool in the ocean, which is conducive to carbon sequestration and enhances ocean carbon sinks, helping to achieve the goals of "Ocean Negative Carbon Emissions" and "Carbon Neutrality". Future research should continue to focus on developing and using advanced instruments and equipment to accurately identify and quantitative the chemical composition of precipitation DOC, to have a deeper understanding of the bioavailability/inertness characteristics of precipitation DOC. At the same time, new numerical simulation techniques should be developed and utilized to conduct in-depth research on the spatiotemporal heterogeneity of atmospheric DOC wet deposition fluxes with different properties of on the global scale, and quantify the indirect wet deposition flux of atmospheric DOC. On this basis, elucidating the significance and value of atmospheric DOC wet deposition as one of the new pathways for improving global ocean carbon sequestration, so as to gain a deeper understanding on the position and role of atmospheric deposition in global carbon cycling and ocean “missing carbon sink” research.

To deeply understand the nitrogen cycling process in alpine forest small watersheds in the northeast of the Tibetan Plateau, the throughfall, soil water and surface runoff at two alpine forest sites in Datong and Huangyuan in the Hehuang Valley in the Tibetan Plateau were studied from April to September 2022. The concentration and flux of dissolved inorganic nitrogen (DIN) were monitored, and the distribution characteristics of nitrogen and oxygen (N and O) isotopes of nitrate (NO₃⁻) along the hydrological path (from throughfall to soil water and then to surface runoff) was analyzed via stable isotope technology. The results showed that the average nitrogen deposition in Datong and Huangyuan (3.60kg/(hm²·a)) was higher than that in the Tibetan Plateau (2.94kg/(hm²·a)), and the nitrogen deposition in Huangyuan (4.17kg/(hm²·a)) was higher than that in Datong (3.02kg/(hm²·a)). The average concentration of NO₃⁻ in soil water at the two alpine forest small watersheds was 5.78mg/L. The average δ¹⁸O-NO₃⁻ ((−1.54±9.77)‰) in soil water was lower than that in throughfall ((74.2±0.01)‰), indicating that nitrification occurred in alpine forest soil. Over 90% of the NO₃⁻ in soil water was from soil nitrification using the end member model analysis, and the remaining approximately 10% might be came from atmospheric deposition. The average concentration of NO₃⁻ in surface runoff at the two alpine forest small watersheds was 5.73mg/L. The δ¹⁸O-NO₃⁻ and δ¹⁵N-NO₃⁻ in surface runoff were enriched along the growth trend of 1:2, indicating that a denitrification process occurred in surface runoff. The δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻ in the Tibetan Plateau alpine forests decreased from throughfall to soil water, and then increased from soil water to surface runoff.

Hasuhai Lake was selected as the research object, where surface sediment samples were collected from 19 sampling points during three water periods: April 2023 (dry season), July 2023 (wet season), and September 2023 (normal season). The concentrations of seven heavy metals (As, Cr, Cd, Cu, Pb, Zn, and Hg) were determined, with all metals except Cr being detected. Subsequently, their pollution levels and spatial distribution characteristics were analyzed. The geo-accumulation index (I_geo) and potential ecological risk index (RI) were used to assess the potential ecological risks of six heavy metals, respectively. The correlation analysis (CA), principal component analysis (PCA) and positive matrix factorization (PMF) models were utilized to analyze the sources and relative contributions of heavy metals in surface sediments. The results indicated that the average contents of six heavy metals in both dry and wet season exceeded the background values of Inner Mongolia stream sediments, and the average contents of five heavy metals except As in normal season exceeded the background values of Inner Mongolia stream sediments. The average contents of Cd and Hg exceeded the background values of Chinese stream sediments in the three water periods. Spatially, the distribution of heavy metals content in surface sediments of each water period is significantly different. The high value of heavy metals content in the dry season is concentrated in the east and west of the lake area, the wet season is mainly concentrated in the north and south of the lake area, and the normal season is mainly concentrated in the middle of the lake area. The results of the geo-accumulation index method and the potential ecological risk index method revealed that Cd and Hg were the main heavy metals elements causing ecological risks in the three water periods, and the mean values of RI in each water period were 590.42, 503.73 and 570.07 respectively, indicating a strong potential ecological risk. The sum of the contribution rates of Cd and Hg to RI values in the three water periods exceeded 90%. The main sources of heavy metals in surface sediments were identified as agricultural production activities and transportation (32.5%), industrial activities (22.7%), natural sources (20.1%), and mining activities (24.7%).

In response to the challenge of coexisting high concentrations of fluoride (F^-) and sulfate (SO₄^2-) in photovoltaic wastewater, based on the principle of nucleation crystallization pelleting process (NCP), its efficacy and mechanisms for removing F^-in such ion coexistence systems were thoroughly investigated. Our study demonstrated that under conditions (nucleation inducer dosage 4.46gMgCl₂/gF, flow rate 67.8×10^-4m³/h, static bed height 30%, and seed particle size 80~100mesh, F^- removal efficiency reached up to 90%. To further validate the stability of the process system, continuous flow defluorination experiments were conducted over 120h. In the first stage (0~40hours), F^- removal efficiency stabilized at approximately 89%, increasing to over 92% in the second stage (40~120hours), with granule purity exceeding 90%. Analysis using XRD and Roman revealed that F^- predominantly adhered to seed surfaces in the forms of magnesium fluoride (MgF₂) and sodium magnesium fluoride (NaMgF₃). Static water contact angle tests and SEM-EDS characterization indicated that granules exhibited greater hydrophobicity compared to the raw seeds and formed a loose porous structure, thereby increasing their specific surface area and enhancing F^- removal. The ZP revealed that in pH 6~8, the seed surface was positively charged, and F^- was mainly concentrated around the surface of the seeds by electrostatic attraction, and then driven by the inducer to nucleate and grow into dense granulation on the surface of the seeds, effectively separating F^- from water.

Electroplating is one of the most significant sources of perfluorinated and polyfluoroalkyl substances (PFASs) in the environment. In this study, the occurrence of PFASs in soil of a relocated electroplating plant was analyzed. The probabilistic health risk was evaluated using Monte Carlo simulation, and the soil screening levels of PFASs were suggested. The soil samples were detected with 8PFASs, and perfluorooctane sulfonate (PFOS) was detected with the highest detection frequency of 89% and concentration of 388ng/g among the targeted PFASs. The distribution of PFASs in soil was impacted by the locations of production units. The total concentration and concentrations of single PFAS such as PFOS, perfluorohexane sulfonate (PFHxS) were significantly higher in soil at chromium plating department (P<0.05). Intake through human oral exposure of soil PFASs accounted for 75.2%~77.6%. Carcinogenic risk of perfluorooctanoic acid (PFOA) was 6.22×10^-11, showing no carcinogenic risk in soil. Non carcinogenic risk quotient of PFOS was larger than 1based on the deterministic values of the exposure factors, while other PFASs showed no non carcinogenic risk. Monte Carlo simulation showed that the risk quotient of PFOS ranged from 0.731 to 5.38, with 95% quantile being 3.85. The 95% quantile values of risk quotient of other PFASs were between 8.77×10^-6 and 0.0137. The soil screening levels of targeted PFASs ranged from 78 to 38826ng/g, and PFOS was found to have the most strict level of 78ng/g.

In order to study the emission characteristics of VOCs from the electronics-manufacturing industry and associated health risk assessment, ten typical electronics enterprises were selected to carry out sample collection and VOCs detection. Moreover, the impacts of VOCs on human health were evaluated by the US EPA and ACGIH methods. The results showed that: The concentrations of VOCs emitted from different types of electronic enterprises exhaust gas were different. The VOCs concentrations in the semiconductor devise and electronic terminal product were relatively higher than those in the display device and printed circuit board, and the VOCs concentrations were 13.41~13.63, 3.34~86.11, 7.86~9.75 and 4.31~4.67mg/m³, respectively. The main organic group in semiconductor devise exhaust gas was alkanes (70.56%~70.78%), and dimethylpentane (32.03%~33.60%) was the main VOCs species. The main organic group in display device exhaust gas and printed circuit board exhaust gas were both OVOCs, accounting for 93.48%~95.87% and 92.27%~93.05%, respectively. Additionally, the highest mass fraction were acetone (91.89%~94.99%) and isopropanol (80.36%~83.07%) in display device and printed circuit board. Due to the different production products, VOCs components were different in the electronic terminal product, but mainly OVOCs, aromatics and alkanes. The coefficient of divergence between different enterprises was 0.67~0.91, indicating that VOCs source profiles must not be similar. Total hazard ratio for non-cancer risk in semiconductor devise was the highest (484.35), followed by display device (447.46), electronic terminal product (11.74~87.35) and printed circuit boards (2.25), suggesting long-term exposure of various electronic industries would cause non-cancer health hazards. The LCRs from semiconductor devise (1.63×10^-3) and electronic terminal product (1.64×10^-4~5.16×10^-3) were much higher, suggesting that these enterprises have a certain cancer risk. The LCRs from display device and printed circuit board were 1.74×10^-5 and 1.40×10^-5, indicating that these enterprises have a high probability cancer risk. The total E_i from electronic terminal product was the highest, while that from display device was the lowest. However, the E_i in different electronics industries were lower than 0.1, indicating that VOCs emitted from these industries may not generate many harmful effects to the workers. The results of the cancer risk assessment using the EPA and ACGIH methods vary significantly. This is mainly because two methods have different limiting indicators for the reference concentration of VOCs species exposure. But on the whole, the health risks from VOCs emitted in the electronic terminal product and semiconductor devise were much higher than in the other two industries. Therefore, to ensure the safety of workers, measures for controlling VOCs should be strengthened.

The effects of PM_2.5 and its constituents (SO₄^2-, NO₃^-, NH₄⁺, OM, BC) on fasting blood glucose and lipid levels in the short-term were examined in the “Jinchang Cohort”. The daily average concentrations of PM_2.5 and its constituents from 2010to 2015 in Jinchang City were sourced from China's Near Real-Time Air Pollutants dataset. Individual exposure was determined by matching the study subjects' residential addresses with pollution data. Generalized estimating equations were used to analyze the short-term effects of PM_2.5 and its constituents on glucose and lipid indicators. Generalized additive mixed models were used to create exposure-response curves and perform stratified analyses. The findings showed that PM_2.5 and its constituents had delayed effects on blood glucose and lipid levels. Specifically, higher concentrations of PM_2.5, SO₄^2-, NO₃^-, NH₄⁺, and OM correlated with increased levels of FPG, TC, HDL-C, and LDL-C, while TG showed a decrease. PM_2.5 and SO₄^2- exhibited more pronounced effects on fasting blood glucose levels in males, whereas PM_2.5 and its five components had more significant impacts on lipid levels in females, individuals aged 60 years or older, those who are overweight or obese, individuals in prediabetic stages, and those with hypertension. Therefore, short-term exposure to PM_2.5 and its components correlates with abnormal blood glucose and lipid levels in the population. Thus, various high-risk groups should adopt self-protection measures accordingly.