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%).

This study delved into the origins and transformation processes of nitrate in the groundwater of the Datong Basin, utilizing hydrochemical analysis alongside multi-isotope techniques (δ¹⁸O-H₂O, δ¹⁵N-NO₃^- and δ¹⁸O-NO₃^-). With the MixSIAR model, we quantitatively assessed the contribution of various pollution sources. Research results are as follows, the mean concentrations of NO₃^--N, NO₂^--N and NH₄⁺-N in groundwater were found to be 32.07,0.96和0.61mg/L, respectively, with NO₃^--N being the most prevalent. Remarkably, the peak concentration of NO₃^--N soared to 538.61mg/L, surpassing the Class III groundwater quality benchmark (20mg/L) by a staggering 27 times, with a 39.13% exceedance rate. The NO₃^--N concentration decreased as groundwater depth increased: shallow groundwater averaged at 34.26mg/L, middle groundwater at 22.05mg/L, and deep groundwater at 13.07mg/L. Nitrogen transformation in groundwater was primarily driven by nitrification, whereas denitrification played a minor role. The primary culprits behind nitrate pollution in groundwater were identified as sewage and manure, soil nitrogen and chemical fertilizers. Their respective average contribution rates were as follows: in shallow groundwater, sewage and manure accounted for 33.6%, followed by soil nitrogen at 33.5% and chemical fertilizers at 21.5%. For middle groundwater, the rates were 43.3% for sewage and manure, 34.4% for soil nitrogen, and 18.1% for chemical fertilizers. In deep groundwater, soil nitrogen led with 54.4%, chemical fertilizers followed at 25.1%, and sewage and manure contributed 18.5%. An uncertainty analysis revealed that the contribution rates of chemical fertilizers and soil nitrogen carried significant uncertainty, indicated by their relatively high UI₉₀values. The research results provide a reference for understanding nitrogen transformation and identifying pollution sources in groundwater.

In Momoge Nature Reserve, three distinct water bodies were selected for the investigation of the composition, spectral characteristics, and sources of dissolved organic matter (DOM) utilizing three-dimensional excitation emission matrix spectroscopy in conjunction with parallel factor analysis (PARAFAC). Additionally, two-dimensional correlation spectroscopy combined with structural equation modeling was employed to analyze the variations of DOM components and their relationships with water quality parameters. The results indicated that the DOM in the water bodies originated from both endogenous and exogenous sources, which has obvious humification characteristics. Five components were identified as microbial metabolites (C1), fulvic acid-like (C2 and C4), humic acid-like (C3) and tryptophan-like (C5) through three-dimensional fluorescence coupled with PARAFAC. Of five components, C1content was the highest (41.37%). The changing sequence of DOM components along the direction of water flow was characterized by 2D-COS as follows: C4→C2→C3→C1→C5, with humic-like substances showing greater variation than tryptophan-like substances, and the content of tryptophan-like substances being relatively stable. The humification degree of DOM directly affected the water quality status with influence weight of 46.17%. The water quality was indirectly impacted by DOM components C2 and C3 with a 17.59% influence weight. Insight into the response mechanism of DOM properties to water quality in Momoge Nature Reserve could provide a theoretical basis for the ecological protection of nature reserves.

In order to explore the characteristics and influencing factors of nitrogen export at the watershed scale during storm events, this study carried out water quality and quantity monitoring of six typical storm events in the Fengyu River Watershed in the upper subbasin of Erhai Lake in Basin 2022 and 2023. The changes of nitrogen export during rainfall-runoff process and the influence mechanism of rainfall intensity, duration, flow and other factors on nitrogen load were investigated. The results indicated that it was more likely to cause larger rainfall runoff when the antecedent soil moisture was highter in the early stage of rainfall event. A large fluctuation of nitrogen concentration was observed when the rainfall intensity reached heavy rain (level 3), indicating that the loss of nitrogen is affected by the rainfall intensity. The analysis of different stages of rainfall events showed that nitrogen was mainly lost in the late stage of the event, accounting for about 62.25%~78.77% of nitrogen load during the whole event, but the amount of nitrogen loss per unit time was large in the early stage of rainfall. For heavy and extreme events, the proportion of nitrogen loss in the middle period was more than 50% of nitrogen load during the whole event, and the nitrogen loss per unit time was the largest in the middle period of the event. Redundancy analysis of rainfall-runoff process and nitrogen loss factors showed that nitrogen concentration change and load export were mainly positively correlated with Antecedent Precipitation Index (API), followed by average rainfall intensity (RI), maximum 30-minute rainfall (I30) and peak flow (FP). Among them, ammonia nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃^--N) were significantly correlated with total discharge (FA), duration of rainfall (RT), and total rainfall (RA). However, dissolved organic nitrogen (DON) has a greater correlation with API and a weaker or negative correlation with other factors.

This study focused on the plant-microbe combined remediation system involving Bacillus megaterium and Celosia argentea L., to explore the impact of Bacillus megaterium on the succession of the rhizosphere microbial community and its role in the remediation of cadmium-contaminated soil. High-throughput sequencing analysis was conducted to examine the structural changes in the rhizosphere microbiota of Celosia argentea at different time points (7th, 21st, and 50th days). The results indicated that in the treatment group, inoculated with B. megaterium, the number of OTUs, diversity indices (Shannon, Simpson), and richness indices (Chao1, Ace) of the microbial community were all higher than those in the control group by the 50th day; the Acidobacteriota, Chloroflexi, Proteobacteria, and Bacteroidetes were the core groups within the microbial community; B. megaterium was able to dominate the rhizosphere microbial community in the early stages but its relative abundance gradually declined from 12.01% to 1.17% over the 50days; Functional prediction of the soil microbial community showed that B. megaterium mainly promoted the C and N cycle within the microbial community, potentially exerting a positive influence on the functionality and stability of the microbial community; B. megaterium significantly increased the cadmium content in the leaves of C. argentea and the bioavailable cadmium content in the rhizosphere soil by 40.3% and 17.6%, respectively. This study provides a theoretical foundation and empirical data support for optimizing plant-microbe combined remediation techniques and understanding the succession patterns of microbial communities in plant-microbe combined remediation systems.

Addressing the drawbacks of iron-based tailings, such as high salinity and alkalinity, low nutrient content, poor water retention, and difficulty in effective utilization, this study utilize the functional microbial system to improved and restored the ecological function of iron tailings, and alfalfa was chosen as the pioneer plant to study the effect of the composite flora on the improvement and restoration of iron tailings by analysing the growth indexes of the plants. Results from pot experiments indicated that the average height of alfalfa in the treatment groups increased by 63.99% compared with the control group, with a decrease in tailings pH and a significant increase in nutrient elements such as urease enzyme activity, catalase enzyme activity and effective phosphorus. Microbial diversity analysis revealed that the abundance of nitrogen-fixing related microbial groups, such as the Nitrospirae, increased by approximately one-fold compared to the untreated groups. Therefore, the functional microbial system has the potential to regulate the acidity of iron tailings, provide nutrients to promote plant growth, increase the abundance of sterol bacteria microbial communities, enhance metabolic capabilities and nitrogen-fixing potential, and contribute to rehabilitate of iron tailings.

To understand the characteristics of microbial communities along the anaerobic ammonia oxidation (ANAMMOX) system, this study explored the diversity, structure, species network, and functional features of microbial communities in sludge with different morphologies along the flow direction in a long-term operated up-flow anaerobic sludge bed (UASB) ANAMMOX system. The results showed significant differences (P<0.05) in the abundance of AnAOB genes in sludge with different morphologies along the anaerobic ammonia oxidation system. The abundance of AnAOB genes in the bottom granular sludge (KL) was 2.12×10¹⁰copies/g VSS, which was significantly higher (P<0.05) than that in sludge with other morphologies along the system. There were significant differences (P<0.05) in the microbial diversity of sludge with different morphologies along the system, but no obvious change patterns were observed. The dominant bacterial phyla (relative abundance>1%) in sludge with different morphologies were Chloroflexi, Planctomycota, Proteobacteria, Bacteroidota, Acidobacteriota, and Actinobacteriota. The top 10genera in terms of relative abundance were norank_f_norank_o_SBR1031, Candidatus_Kuenenia, norank_f_Anaerolineaceae, Nitrosomonas,Limnobacteriota, norank_f_PHOS-HE36, Denitratisoma, Denitratisoma, and OLB13norank_f_ A4b. There were significant differences (P<0.05) in relative abundance among different samples. There were significant differences (P=0.001) in the microbial community structure of sludge with different morphology along the process. Network analysis found differences in the structure and topological properties of microbial networks among different morphologies of sludge. Specifically, the average degree and center tightness of flocculent sludge in sedimentation tank (CD) and biofilm in the effluent pipe (XK) were higher than those in other samples along the system, indicating a closer correlation among microbial communities. PICRUSt2analysis revealed that the abundance of functional genes related to metabolic pathways was significantly higher than that of other functional genes. Additionally, there were significant differences (P<0.05) in metabolic functional genes abundance among different morphologies of sludge along the process. The relative abundance of nitrogen metabolism functional gene hao was much higher than that of norB, while the abundance of the narG gene was 20.8 to 733.9times that of nirS, indicating activeness of partial nitritation and partial denitrification functions within the system. The anaerobic ammonia oxidation system exhibits significant heterogeneity in the microbial communities of sludge with different morphologies along the process, but no distinct regularity is observed.

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 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.

In this research, BPS and BPF with sublethal dose were selected to compare the difference and combined toxicity of neurodevelopmental toxicity in zebrafish from four aspects: developmental phenotype, motor behavior, vascular development and neurotoxicity. The results showed that both BPS and BPF of LC5 induced apparent deformities in zebrafish, such as inhibiting the development of swimming sac and yolk sac. Exposure to BPS and BPF can affect the early motor behavior of zebrafish, which is potentially associated with damage to the cardiovascular system and nervous central system. BPS and BPF caused abnormal cardiovascular development and shortened caudal vein (CV) width in zebrafish. The abnormal transmission of DA, AChE and NO neurotransmitters leads to the impaired development of zebrafish neurons, which has a direct impact on the function of the lateral nervous system, and then leads to the impaired early motor behavior of zebrafish. BPS and BPF show different toxicity differences in specific indicators. BPF exposure is more likely to induce tissue and organ toxicity in zebrafish, while the direct toxicity of BPS is less than that of BPF, which is more manifested at the molecular level, indicating that there is a certain degree of difference in the mode of action of the two. In addition, combined with the analysis of the combined action of concentration addition model, the addition action between BPS and BPF is mainly. The results of this study provide a reference for health risk assessment and risk warning after exposure to BPS, BPF and their mixtures.