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.

The porous two-dimensional carbon nanosheets with high graphitization and defect sites, designated M-C and M-N, were successfully synthesized via molten salt-assisted pyrolysis of glucose, with oxysalts (K₂CO₃ or KNO₃) as additives, respectively. The oxysalts significantly enhanced the specific surface area of the carbon nanosheets. Particularly, KNO₃ promoted nitrogen doping in M-N, resulting in a maximum adsorption capacity for acid orange 7 (AO7) of 480.77mg/g, surpassing that of biochar (BC) from direct pyrolysis and M-BC from molten salt-assisted pyrolysis without oxysalts. The adsorption and catalytic degradation of AO7 removal over carbon materials exhibited a synergistic effect. The catalytic activity of M-N in peroxymonosulfate (PMS) activation was 22.64times that of M-BC and 33.48times that of BC. Additionally, the impact of nitrogen doping and other structural defects on the non-radical pathway-dominated catalytic processes was preliminarily assessed using density functional theory (DFT) calculations. This study indicates that oxysalts can significantly reduce the amount of molten salt required in the preparation of carbon nanosheets, and also provides theoretical guidance for developing bifunctional biomass-based carbon materials for highly efficient organic pollutants adsorption and PMS activation.

Pollen allergy is a global health problem which also has attracted much attention in China, and the incidence is increasing in the northern area. The data of daily airborne pollen concentration, meteorological conditions, vegetation growth and allergic patient were analyzed from 2017 to 2022 in Hohhot of Inner Mongolia Autonomous Region. There were two peaks of pollen dissemination every year. The first peak was in early April, which was a greater proportion of woody plant pollen, with a short duration. The second peak was from August to September, mainly composed of herbaceous plants pollen such as Artemisia of Compositae pollen, with a long duration and had much more serious sensitization effect. The results showed that the effective accumulated temperature of ≥5℃ from January to June was significantly negatively correlated with the start date of the peak pollen dispersal period, while the cumulative precipitation and cumulative sunshine hours from the early stage to the flowering period were significantly positively correlated with the end date of the peak pollen dispersal period. The higher the accumulated temperature was, the earlier the peak period of pollen dispersal started. The end date of peak period would be delayed by the large amount of precipitation and light hours, meanwhile the number of pollen dispersal would increase. There were statistically significant or significant positive correlation between the cumulative value of each meteorological factor or the vegetation index and the monthly average pollen concentration. Appropriate light hours and precipitation, the vegetation would grown well, which would promote pollen dispersal and stimulate an increase in concentration. The number of Allergic Rhinitis patients was consistent with the variation of pollen concentration, and was reaching a peak in August. When the pollen concentration exceeds 100 grains/1000mm², there was a lag period of 0~4days in the peak of AR treatment, among which the most obvious incremental effect was after 2 days. The number of patients was exponentially related to the pollen concentration in a ten-day time range. The above results would provide some practical reference for pollen concentration meteorological forecasting services and the prevention and treatment of AR caused by pollen allergy.

In this study, Six treatments were established: a control (CK), warming (W), increased precipitation (+P30), decreased precipitation(-P30), increased warming and precipitation (W+P30), and increased warming and decreased precipitation (W-P30). Field experiments were conducted to investigate the effects of warming and precipitation changes on the structure and function of soil bacterial communities in dry-crop farmland. Macro-genome sequencing was exployed to examine the composition, diversity, network structure and metabolic function characteristics of soil bacterial communities under varying treatments. The results demonstrated that the W and W+P30 treatments significantly elevated the relative abundance of Alphaproteobacteria, while the W+P30 treatment notably increased the relative abundance of unclassified Chloroflexi. Conversely, the W, +P30, W+P30, and W-P30 treatments significantly reduced the relative abundance of unclassified Actinomycetia. The +P30 treatment resulted in a significant increase in the Shannon, Simpson and Pielou indices, whereas the W-P30 treatment led to a significant reduction in the alpha diversity index of bacteria. Significant differences were observed in the effects of warming, precipitation changes and their interactions on the β-diversity of the bacterial community. The W, +P30, W+P30 and W-P30 treatments exhibited higher complexity and connectivity than the CK treatment. However, the -P30 treatment exhibited lower relevant parameters than CK. The W, -P30 and W+P30 treatments demonstrated an increase in the number of connectivity nodes, whereas the +P30 and W-P30 treatments did not exhibit this increase. The W treatment led to a notable increase in the relative abundance of the circulatory system, while the +P30 treatment resulted in a significantly decreased the relative abundance of xenobiotics biodegradation and metabolism. The -P30 treatment led to a considerable decrease in the relative abundance of the excretory system, and the W+P30 treatment caused a notable decrease in the relative abundance of nucleotide metabolism. It was observed that warming, precipitation changes (either an increase or decrease in precipitation) and their interaction had significant impact on the structure and metabolic functions of soil bacterial in wheat fields.

This study investigated the susceptibility of karst groundwater from surface pollution. A typical karst spring system (the Chaoshuidong in Yichang, Hubei Province of China) was selected to analyze the contamination characteristics, sources, and transport processes of organochlorine pesticides (OCPs). Water, soil, and sediment samples were collected in four seasons for OCP analysis. The results showed that the average concentrations of OCPs in surface water, spring water, soil and sediment samples from Chaoshuidong system were 8.25ng/L, 5.11ng/L, 15.9ng/g and 12.6ng/g, respectively. OCPs concentrations in the Chaoshuidong system were relatively lower than in other regions, with seasonal fluctuations closely correlated to hydrogeological conditions and OCPs transport dynamics. Composition analysis of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs)indicated that HCHs were primarily from agricultural inputs of Lindane(γ-HCH) in the water and sediments, while the technical HCH dominated in the soils. DDTs were mainly a mixture of inputs from technical DDT and dicofol pesticide in all three media. The contribution of OCPs from the soils in the recharge area to the upstream surface water and to the spring water was 87.8% and 58.3%, respectively, and the contribution of OCPs from the spring water in the discharge area to the spring sediments was 64.2%. This study demonstrated that OCPs can be rapidly transported from recharge area to discharge area through two primary pathways: surface transport and underground transport, subsequently contaminating water bodies.

To evaluate the association and combined effects of perfluoroalkyl and polyfluoroalkyl substances (PFAS) and mixtures on hyperuricemia (HUA) and identify key components, this study analyzed data from 2,564 subjects in the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2016 using logistic regression, weighted quantile sum regression, and Bayesian kernel machine regression. Higher levels of perfluorononanoic acid (PFNA), n-perfluorooctane sulfonic acid (n-PFOA), and perfluoromethylheptane sulfonic acid isomers (Sm-PFOS) were positively associated with HUA when PFAS was exposed as a single source (P<0.05). When considered as mixture exposure, PFAS mixtures were positively associated with HUA overall, with a 39.6% increase in the risk of HUA for each quartile increase in PFAS mixtures (WQS index) (OR=1.396,95%CI: 1.180~1.651, P<0.001), and this association was only observed in the female population. n-PFOA and Sm-PFOS were identified as key components, while linear perfluorooctane sulfonic acid (n-PFOS) and perfluorohexane sulfonic acid (PFHxS) may be negatively associated with HUA in the mixture. Potential interactions between various PFAS were also observed. The research findings can provide the latest epidemiological evidence for the study of the association between PFAS exposure and the risk of hyperuricemia, offering a basis for screening key populations.

Microplastics exhibited unique properties and possessed a wide distribution across various environments. The confluence served as a key point for the contamination of microplastics. At present, there was a lack of effective methods to reveal the motion characteristics and accumulation areas of microplastics at the confluence. The motion and fate of microplastics should be accurately captured at the confluence. The three-dimensional hydrodynamic-microplastic transport model for microplastics was established at the confluence. The transport mechanism and fate of microplastics were investigated under varying junction angles and flow ratios through the coupled CFD-DEM method. The results showed that (1) The low velocity zones, including the flow separation, flow stagnation, and downstream of the flow separation, would evolve into regions of microplastic accumulation. (2) Microplastics were primarily influenced by the vortex located in the flow separation, entering the vortex zone from the right bank of the mainstream and gradually forming an elliptical enrichment region. (3) The concentrations of microplastics in the center of the flow separation were positively correlated with the junction angles. (4) There was a linear negative correlation between the concentrations of microplastics and the flow ratios in the center of the flow separation, R²=0.9007. The number of microplastics in the flow separation exhibited a significant negative correlation with the flow ratio at the confluence. The findings of the study would advance the fundamental understanding of microplastic motion in confluences and establish a theoretical framework for precise prevention and control strategies against microplastic pollution.

This study estimated the initial volume mixing ratios of the ambient VOCs measured from 18 April to 31 July 2021 in Linfen, Shanxi Province, using a photochemical age-based parameterization method, and corrected photochemical loss effects.Positive matrix factorization (PMF) was used to conduct the initial-data source apportionment. The results showed that the average volume mixing ratio of total VOCs (TVOCs) during the study period was 17.1×10^-9. The average initial volume mixing ratio of TVOCs in the daytime was 27.2×10^-9, with chemical loss of 10.6×10^-9 and loss rate was approximately 39.0%. Compared with other VOC groups, alkenes had the highest loss rate (66.0%). The chemical losses of isoprene (3.16×10^-9), 1,3-butadiene (1.27×10^-9), and ethylene (1.19×10^-9) were higher than any other species. During the ozone pollution (OP) period, the chemical loss of TVOCs was 15.1×10^-9, which was 1.6times higher than during the non-ozone pollution (NOP) period. During the OP period, the loss rate of alkenes was the highest (81.7%) than the other VOC groups. The losses of isoprene, 1,3-butadiene, trans-2-butene, and trans-2-pentene were 5.05×10^-9, 1.85×10^-9, 1.59×10^-9, and 1.10×10^-9, respectively, substantially higher than any other species. The PMF apportioned results based on the initial volume mixing ratios (i.e., IC-PMF) showed that petrochemical-related enterprise emissions (36.4%), natural gas (17.2%), the mixed source of diesel vehicle emissions and solvent usage (12.9%), gasoline vehicle emissions (9.6%), liquefied petroleum gas (8.6%), biogenic emissions (8.6%), and combustion sources (6.7%) were the main contributors to the ambient VOCs in Linfen during the study period. Compared to the PMF apportioned results based on the observed volume mixing ratios (i.e., OC-PMF), the contribution of biogenic emissions was underestimated by 83.3%, which was substantially higher than those of other sources; followed by the mixed sources of diesel vehicle emissions and solvent usage (22.2%) and the petrochemical-related enterprise emissions (19.7%). Meanwhile, the IC-PMF results suggested that the sources with higher contributions during the OP period were the petrochemical-related enterprise emissions and biogenic emissions, accounting for 24.1% and 21.7%, respectively. According to the IC-PMF apportioned results, the estimated results using the ozone formation potential (OFP) model showed that petrochemical-related enterprise emissions was the highest contributor to the OFP, with the contribution of 50.7% to the total OFP, followed by biogenic emissions (24.8%) and the mixed source of diesel vehicle emissions and solvent usage (10.4%). The emission sources with higher contributions to the OFP during OP period were biogenic emissions and petrochemical-related enterprise emissions, reaching 52.6% and 27.8%, respectively.

This study aims to investigate the VOCs pollution characteristics in the high-tech industrial zone of Tongchuan City, a medium-sized city in the Fenwei Plain, by using online monitoring methods to measure the concentration of environmental VOCs components (a total of 115species) in the atmosphere of the Tongchuan High-tech Industrial Development Zone, thereby obtaining a high-resolution time series and seasonal variation patterns of atmospheric VOCs. The Positive Matrix Factorization(PMF) model was utilized to identify the primary sources of VOCs, and the Maximum Incremental Reactivity (MIR) method was applied to quantify the Ozone Formation Potential (OFP) of VOCs. Furthermore, the Hazard Index (HI) and Lifetime Cancer Risk (LCR) of toxic VOCs were calculated. The findings revealed that during the monitoring period, the average values of φ (TVOCs) in spring, summer, and winter were respectively (69.03 ± 47.48)×10^-9, (92.66 ± 37.54)×10^-9, and (134.90± 74.58)×10^-9, with the top three components in each season being consistent (alkanes > alkenes > aromatics). PMF source apportionment results indicated that the sources of atmospheric VOCs in the development zone were primarily from chemical companies, motor vehicles, and combustion emissions (each contributing over 20%). OFP assessment outcomes revealed that OVOCs were the major contributing components in all seasons, with ethanol, acetaldehyde, and ethylene being the primary species. Health risk assessments indicated that the HI in spring, summer, and winter all exceeded acceptable levels (HI > 1), suggesting non-carcinogenic health risks to the exposed population. Acrolein, in particular, had a notably high hazard index, exceeding 1in all seasons. The lifetime cancer risks in spring, summer, and winter were 1.68×10^-5, 1.57×10^-5, and 8.42×10^-5, respectively, indicating a slight carcinogenic risk in all seasons.

When drinking water quality and hydraulic conditions change, the solid-liquid balance between pipe scales and water in drinking water distribution systems (DWDSs) will be destroyed, causing iron release and secondary pollution of drinking water. In this paper, dynamic experimental systems were set up to analyze the process of iron release in DWDSs under coupled changes of flow rate (v), pH, sulfate (SO₄^2-), and alkalinity (Alk). Principal component regression was used to establish the model for predicting the release of iron. The results indicated that under the condition of v=0.12m/s, pH=6.5, [SO₄^2-]=250mg/L, and Alk=100mg/L CaCO₃, the total iron concentrations in steel and cast iron pipes reached the maximum of 1.423mg/L and 0.184mg/L, respectively. A large amount of flaky and scattered spherical structures were observed in steel and cast iron pipe scales, with α-FeOOH being the main component. After the experiment, the contents of α-FeOOH, γ-FeOOH, and Fe₂O₃ in both pipe scales increased, while those of Fe₃O₄ decreased. The predictive model showed that the total iron concentrations were negatively correlated with pH and Alk, and positively correlated with SO₄^2- and v. The order of the influences of the four factors was: v > pH > Alk > SO₄^2-.