The determination of environmental background values for groundwater was recognized as a prerequisite and key step for the scientific identification, evaluation, and prevention of groundwater pollution. In this paper, the development history of groundwater environmental background value research was reviewed both domestically and internationally. Existing calculation methods for groundwater environmental background values were discussed along with their respective advantages and disadvantages. The research paradigm for background value reasonableness validation analysis and cause analysis was systematically summarized. Finally, existing problems in current groundwater environmental background value research were identified, and future development trends were projected. It was observed that inconsistencies in naming and definitions of groundwater environmental background values persisted among scholars worldwide. Although the influence of human activities on groundwater chemical components had been considered, quantitative determination of the "low human activity impact" threshold in conceptual frameworks remained challenging. Methods for determining environmental background values were generally categorized into mathematical-statistical approaches, model-based methodologies, and other alternative techniques. Each method was found to possess distinct advantages and limitations. The combination of hydrochemical analysis with mathematical statistics was demonstrated to emerge as one of the representative integrated approaches for calculating groundwater environmental background values, though methodologies for trace and micro-component analysis were noted to require further development. The reasonableness of environmental background values was typically assessed through comprehensive evaluation of multiple factors including surrounding pollution sources, hydrogeological conditions, lithological characteristics, land use patterns, pollution percentage indices, and stable isotope results. Regional geological settings and hydrogeological conditions were identified as primary controllers of groundwater environmental background values, while biogeochemical processes were determined to dominate micro-enrichment mechanisms. Based on established environmental background values, groundwater pollution levels were effectively evaluated, pollution risk areas were scientifically delineated, and reference thresholds were provided for environmental regulation and remediation targets. Future priorities were emphasized to include the urgent establishment of a global groundwater environmental background value database, enhanced application of existing background value data, and strategic utilization of big data analytics. These measures were proposed to optimize global groundwater resource protection and pollution control strategies under combined pressures of climate change and anthropogenic impacts.

The impacts of dry-rewetting and freeze-thaw cycles on DTPA-extractable Pb（II）content and Pb speciation in soils and material structure of weathered coal-based immobilized microbial materials were investigated through a controlled simulated experiment. This study aimed to explore the mechanisms through which these two factors affect the effectiveness of lead-contaminated soil remediation using selected microbes. The results showed that after 35 dry-rewetting cycles, the DTPA-extractable Pb（II）content in low-concentration lead-contaminated soil（LS）and high-concentration lead-contaminated soil（HS）decreased by 46.41% and 29.42%, respectively, compared to the initial levels. After 35 freeze-thaw cycles, the content in LS and HS decreased by 40.06% and 32.77%, respectively. Additionally, the residual fraction of Pb in LS increased under both dry-rewetting and freeze-thaw treatments. Structural analysis revealed that the surface of weathered coal-became rougher, with increases in specific surface area, oxygen-containing functional groups, and Pb adsorption sites increased after dry-wet and freeze-thaw cycles. These changes enhanced complexation with functional groups thereby improving the stability of the passivation effect on lead contamination.

To investigate the impact of density currents brought by the mainstream of Yangtze River on the distribution of dissolved CH₄ in its tributaries, three representative tributaries-Xiaojiang, Daning, and Shennong Rivers were selected as the study sites. Spatial measurements of dissolved methane（CH₄）concentrations in the surface water were conducted using a Fast-Response Automated Gas Equilibrator（FaRAGE）coupled with a greenhouse gas analyzer. The results were shown to vary in CH₄ concentrations among the tributaries, with average concentrations being（0.06±0.02）µmol/L in Xiaojiang,（0.17±0.12）µmol/L in Daning, and（0.16±0.14）µmol/L in Shennong Bays. The CH₄ concentrations in these three bays were also found to exhibit distinct spatial heterogeneities. In Xiaojiang Bay, a pattern was observed where high surface concentrations and low bottom concentrations were present in the midstream, while higher concentrations were found at the bottom compared to the surface in both the upstream and downstream areas. Comparable distribution patterns of CH₄ concentrations were noted in Daning Bay and Shennong Bay, characterized by higher concentrations upstream compared to downstream, and higher concentrations at the bottom layer relative to the surface layer. It was found that the distribution of dissolved CH₄ concentrations in the tributary bays was influenced by environmental factors. Furthermore, the density currents from the mainstream were not only found to dilute the dissolved CH₄ concentrations in the bays but also indirectly altered their distributions by influencing the hydrological and hydrodynamic processes within the tributary bays. The integrated effects revealed the complex dynamic processes of CH₄ production and consumption within the bay ecosystems, which were of great significance for understanding and predicting the greenhouse gas emissions from the bays of the Three Gorges Reservoir.

Hypoxia has become a prevalent phenomenon in the plain river network region. To reveal the causes of hypoxia in these regions, the Sihu Canal in the Hanjiang River Basin, one of China's most important freshwater aquaculture areas, was selected as a case study. The spatiotemporal variations in water quality, including dissolved oxygen（DO）and nutrients, were analyzed for the period 2010~2023, and the spatial distribution of nutrients in water and sediments were investigated. The impact of parameters such as water temperature, ammonia nitrogen, and flow on DO levels in the water was evaluated using a Random Forest model. The results indicated significant seasonal fluctuation in DO levels, which exhibited a 'V'-shaped pattern throughout the year. DO concentrations were relatively low during flood seasons, while during non-flood seasons the requirements for Class III surface water quality were generally satisfied. In 2021, severe hypoxia（DO<2mg/L）was observed, with the annual hypoxic days amounting to 79,116, and 96 at the Yunlianghu, Xinhecun, and Xintan sections respectively. Evident hypoxic zones were identified in the mid- and upstream sections of the Sihu Canal, where DO concentrations ranged from 2.61 to 3.22mg/L. From 2010 to 2023, the water quality of the Sihu Canal consistently ranged from Class IV to Class V, with occasional further deterioration recorded. The main parameters exceeding the standards were identified as DO, permanganate index, ammonia nitrogen, and total phosphorus. The total nitrogen and phosphorus contents in the sediments ranged from 857.70 to 2846.87mg/kg, and 545.99 to 2475.59mg/kg, respectively, indicating that the sediments were subjected to mild to moderate pollution, with tributaries being more polluted than the main canal. High accuracy in predicting DO levels was demonstrated by the Random Forest model, which yielded an R² of 0.995 and an RMSE of 0.2085. Water temperature had a relative importance exceeding 35% in influencing DO levels, followed by pH, ammonia nitrogen, conductivity, turbidity, and flow. To mitigate the hypoxic conditions during flood seasons, it was recommended that the systematic management of the basin be strengthened, the water quality of shrimp-rice and aquaculture drainage systems be improved, and the operation and scheduling of pump stations be optimized.

Under the synergistic advancement of global climate governance and China's "Dual Carbon" strategy, the development of forestry carbon sink systems urgently required breakthroughs in carbon quantification bottlenecks within seedling production. Edible raw material forests played an important role in improving the ecological environment and increasing economic growth, and estimating the carbon footprint of seedling production was crucial for assessing the carbon sink of forestry. By surveying existing star anise nursery operations for primary data in Guangxi, a new process-based life cycle inventory（LCI）dataset an 8cm×12cm star anise seedling of a typical edible raw material forest production system was created, covering three stages from seed collection to the transportation of seedlings to retailers. Incorporating the new LCI data into life cycle assessment（LCA）method, the total global warming（GW）impact of a star anise seedling was 0.145kgCO₂e, of which energy and materials consumption constituted 57.2% and 28.8% of total emissions. Electricity use is dominated by irrigation demands（75.9%）and water was estimated to be just over half of these emissions（60%）. Among the production activities, the total environmental impact of the product was dominated by the irrigation at the field container seedling stage, which contributed 0.07kgCO₂e/seedling. In this case, the change in energy consumption had a notable impact on the carbon footprint, with a sensitivity of 0.804. Among them, the input of diesel had the largest impact on carbon footprint（42.4%）. The results indicated that optimizing clean energy structures and implementing efficient water and nutrient management strategies could significantly reduce carbon emissions during seedling cultivation and offered practical guidance for advancing carbon labeling systems for edible forest products and supported forestry carbon neutrality progress.

Based on panel data of 284 cities at or above the prefecture level in China from 2012 to 2022, this paper studied the impact of new quality productivity on green innovation efficiency and the moderating effect of urbanization in this process by using fixed effect model, moderating effect model and general nesting spatial model. It was found that:（1）New quality productivity was confirmed to significantly enhance green innovation efficiency, a conclusion that still held after a series of robustness tests.（2）The promoting effect of new quality productivity on green innovation efficiency was most significant in the eastern region, followed by the central region, while no significant impact was observed in the western region.（3）Urbanization played a positive moderating role in the process of new quality productivity promoting green innovation efficiency.（4）New quality productivity was shown to generate positive spatial spillover effect that effectively improved green innovation efficiency of neighboring regions. Therefore, it was recommended to actively cultivate new quality productivity, optimize the innovation environment according to regional characteristics, vigorously promote the green urbanization process, and establish efficient regional cooperation mechanism to fully unleash the potential of new quality productivity and accelerate the green transformation of the economy and society.

Based on the monitoring data of 47 typical fine chemical in-process sites in Shanghai, the pollution of soil and groundwater in this industry was analyzed, the health risk of pollutants was evaluated, and high-priority pollutants were screened. The findings revealed that the industries with the highest pollution risk were those involved in basic chemical raw material manufacturing, pesticide manufacturing, paint and similar product manufacturing, and specialty chemical product manufacturing, collectively representing 70% of the contaminated sites. In comparison, the chemical raw material manufacturing industry exhibited a pollution risk of 54.55%, while the daily chemical products manufacturing industry showed the lowest pollution risk（0%）. The most frequently detected contaminants in the soil and groundwater included arsenic, lead, mercury, nickel, zinc and total petroleum hydrocarbons（TPH）, which were present at relatively low concentrations. In contrast, benzene derivatives（BTEXs）, polycyclic aromatic hydrocarbons（PAHs）, and most chlorinated hydrocarbons（CAHs）were detected in small areas of certain sites, indicating more severe contamination levels. Furthermore, cyanides, antimony, manganese, and tetrachloroethylene were found in larger areas of certain sites, representing the highest contamination levels. The pollution profile of the basic chemical raw material manufacturing industry was the most complex, involving cyanide, antimony, arsenic, manganese, mercury, CAHs, PAHs, and TPH. On the other hand, pesticide manufacturing, paint and similar product manufacturing, and specialty chemical product manufacturing industries were primarily contaminated by CAHs and BTEXs. A notable observation was the evident soil-water compound pollution phenomenon involving chlorinated hydrocarbons and benzenes. Through comprehensive environmental exposure and human health risk assessments, the following were identified as high-priority soil pollutants: arsenic, chloroform, 1,2-dichloroethane, benzo[a]pyrene, antimony, vanadium, trichloroethylene, lead, carbon tetrachloride, and naphthalene. For groundwater, the high-priority pollutants included trichloroethane, tetrachloroethylene, cyanide,1,2-dichloroethane, benzene, methylene chloride, nickel, antimony, manganese and trichloroethylene.

Antibiotic resistance was recognized as one of the most critical public health challenges confronted by humanity in the 21 st century. Metal nanomaterials were regarded as potent alternatives in the post-antibiotic era, attributed to their exceptional biocidal efficacy and tunable properties. However, it was demonstrated through recent studies that not only could resistance to nanomaterials themselves be developed by bacteria, but the physiological characteristics of bacteria could also be altered, consequently leading to enhanced antibiotic resistance. The antibiotic resistance variations induced by metal nanomaterials were systematically reviewed, with underlying mechanisms being elucidated through three key aspects: the interfacial interactions between nanomaterials and bacterial membranes, the occurrence of bacterial genomic mutations, and the horizontal transfer of resistance genes. This investigation was designed to establish a theoretical framework for innovating next-generation nano-antimicrobial agents, while simultaneously promoting the application of nanomaterials in combating antimicrobial resistance on a global scale.

To investigate the influence of microbial communities on arsenic speciation in lake sediments of the Hetao Basin in Inner Mongolia during the ice-bound period, the sediments from Wuliangsuhai（WLSH）were taken as the research object. Using 16SrRNA high-throughput sequencing technology, the structural characteristics of microbial communities in WLSH sediments during the ice-bound period were studied. Additionally, methods such as redundancy analysis（RDA）, correlation analysis, and co-occurrence network analysis were employed to explore the response relationship between sediment microbial communities and arsenic speciation during the ice-bound period. The results indicated that, apart from the residual arsenic, strongly adsorbed arsenic and arsenic co-precipitated with AVS（Acid-extractable sulfides in sediment）, carbonates, manganese oxides, and poorly crystalline Fe hydroxides accounted for a relatively high proportion in the sediments of WLSH during the ice-bound period. When the sedimentary environment was unstable during the ice-bound period, there was a risk of secondary release of arsenic in the sediments of WLSH. The microbial community in the WLSH sediments during the ice-bound period exhibited abundant diversity, and the richness and diversity of microbial community species showed obvious spatial distribution characteristics. There was a significant collinear relationship between microbial communities and arsenic speciation during the ice-bound period, with Thiobacillus, Bacillus, Steroidobacter, Desulfosarcinaceae, and Anaerolinea exhibiting the most pronounced effects on arsenic speciation. Furthermore, adsorbed As, As co-precipitated with AVS, carbonates, manganese oxides, and poorly crystalline Fe hydroxides, as well as As in pyrite, could mutually transform during the ice-bound period, and Thiobacillus and Steroidobacter played crucial roles in this transformation process. This study aims to explore the impact of microbial communities on arsenic speciation in sediments of WLSH during the ice-bound period, providing a microbial theoretical basis and scientific evidence for lake arsenic pollution control. It provides significant implications for the rational development and utilization of water resources, as well as the protection and restoration of aquatic ecological environments.

CoFe₂O₄@MoS₂ was prepared by the hydrothermal method and used to activate permonosulfate（PMS）for the degradation of ciprofloxacin（CIP）in water. The successful preparation of CoFe₂O₄@MoS₂ was confirmed by the characterization results obtained from SEM and XRD. Degradation results showed that the removal rate of CIP in the CoFe₂O₄@MoS₂/PMS system can reached 74.38% in 120minutes, which is higher than the sum of the individual CoFe₂O₄@MoS₂ and PMS systems, verifying the activation ability of CoFe₂O₄@MoS₂ on PMS. The quenching experiment results indicated that the main oxidative active species in the system are ^●OH、SO₄^●- and ¹O₂, with SO₄^●- and ¹O₂ playing a major role in the degradation of CIP. Based on density functional theory combined with HPLC analysis, eight possible products were obtained and two possible degradation pathways of CIP were proposed. The environmental risks of the degradation products were evaluated and predicted using the TEST program, and it was shown that, compared with the parent compound, most products exhibited reduced acute toxicity, weakened mutagenicity, decreased bioaccumulation and developmental toxicity, and significantly lower ecotoxicity. Additionally, the CIP removal rate of the CoFe₂O₄@MoS₂/PMS system can still reached 60.04% after four cycles, and the XRD results demonstrated that the crystal structure of the catalyst did not undergo significant changes before and after the reaction, indicating the high efficiency and stability of the catalyst.