This paper optimized the traditional comprehensive water quality identification index model（CWQI）and established two improved models: the improved comprehensive water quality identification index model based on game theory（ICWQI_G）, which considered both subjective weight and objective weight, and the improved comprehensive water quality identification index model with phased period combination weights（ICWQI_P）, which incorporated the variation of weight time. Taking Qionghai Lake as a case, the water quality monitoring data of 11 sampling sites in different hydrological periods from 2020 to 2023 were selected to evaluate the water quality of Qionghai Lake using ICWQI_G and ICWQI_P models, which could verify the scientific validity of the improved comprehensive water quality identification index method. The results show that, compared with the traditional CWQI model, the improved ICWQI_G and ICWQI_P models both take into account the factor of TP exceedance. The evaluation results could better reflect the actual water quality of the study area, and sensitively identify more pollution risk areas and severely polluted water bodies.ICWQI_P used phased weights instead of uniform weights, compensating the effect of environmental factors such as such as precipitation on the weight of water quality. This could better identify the key environmental variables affecting water quality in different periods, leading to more accurate and reasonable results. At the same time, based on the improved comprehensive water quality identification index method, it was found that the water quality of Qionghai Lake in 2023 was worse than that in 2020~2022. The pollution degree of the northwestern lake area was higher than that in the eastern and southern lake area. The improved ICWQI_G and ICWQI_P models showed better rationality in the water quality assessment of the Qionghai Lake, providing theoretical support for the refined management of the lake’s ecological environment, and offering important reference value for water quality assessment of other similar water bodies.

Ecological restoration of territorial space is a critical measure for advancing the construction of ecological civilization. Precise identification of areas requiring ecological restoration and rational delineation of restoration priorities are fundamental prerequisites for the scientific and orderly promotion of territorial ecological restoration. This paper selected the Shandong Section of the Yellow River Basin as the research area and quantitatively evaluated the risk of ecosystem degradation using the "ecological resilience and human disturbance" framework. An ecological security pattern was constructed through Morphological Spatial Pattern Analysis（MSPA）, landscape connectivity assessment, and circuit theory models, identifying key ecological factors such as source areas, corridors, pinch points, and barrier points. By overlaying these factors with ecological degradation risks, the priority levels of restoration areas were determined, and corresponding restoration strategies were formulated. The results indicated that the overall risk of ecological degradation in the study area was high, with high-risk areas exhibiting a zonal radiation distribution centered around each city. The influence of rapid urbanization and the expansion of transportation networks on ecological degradation cannot be overlooked. A total of 27 ecological sources, 71 ecological corridors, 71 ecological pinch points, and 51 ecological barrier points were identified as ecological restoration areas. Overlapping ecological degradation risks, ecological restoration areas were divided into priority restoration, general restoration and ecological conservation, and restoration strategies were proposed in conjunction with the characteristics of different ecological elements and their priority order.

Selecting Pearl River as a typical case, over a decade of data tracking and investigation was conducted. Simulated using the analytical data as well as future scenarios of climate warming and river acidification, this study predicted the evolution of nutrient element ratios and trace metal concentrations over the next 80 years. Three significant changes in natural water bodies were suggested: firstly, insufficient carbon source allocation and nutrient accumulation leading to decreased biochemical efficiency; secondly, elevated ion exchange due to acidification, resulting in higher background concentrations of trace elements; lastly, water quality fluctuation inducing the co-release of heavy metals and toxic organic micropollutants and phase distribution shifts, forming a multi-loop feedback of pollution sources. Our study suggests that changes in aqueous solution properties of water bodies are driven by the results of simultaneous occurrence of concentration resonance and convergence effects, which are crucial factors of the physical fields. Combined pollution irreversibly changes the physicochemical properties of water bodies, resulting in a rapid fluctuation of geological background baseline values over decades. Consequently, this necessitates epochal adjustments to the evaluation of natural water body thresholds. A new emergence of water environmental challenges may include element exposure and fate changes caused by the natural evolutions, water quality structure conflicts from continuous inputs and emissions, and the approaching demands for species equity in ecological era.

The coupling and coordinated relationship between ecosystem services and water use efficiency is calculated and analyzed according to the land use and water consumption data from 2005 to 2020 in Xinjiang. The results indicated that food production increased significantly from 2005 to 2020, while other ecosystem services had no significant change. The agricultural water efficiency was greater than 0.649 and increased with rate of 0.023/a from 2005 to 2020. The ecological water use efficiency decreased with rate of 0.013/a, and had significant regional difference. The water efficiency in domestic industry was higher and changed little. The coupling coordination degree of food production and agriculture water efficiency increased with rates of 0.057/a, and achieved highly coordination（0.995）in 2020. The coupling coordination degree of habitat quality and ecological water use efficiency decreased with rate of 0.052/a, and achieved slightly dysregulation（0.251）in 2020. The results indicated that the allocation and utilization efficiency of water resources in agricultural production reached highly coordination in Xinjiang, but the attention of ecological environment water use needs to be improved.

In order to investigate the tolerance of endogenous partial denitrification（EPD）system to different types of low molecular weight polycyclic aromatic hydrocarbons（PAHs）and to explore methods to enhance the impact resistance of EPD systems, this study first acclimated EPD systems with 20mg/L PAHs（phenanthrene and anthracene）, and then added other types of PAHs（anthracene, phenanthrene, and naphthalene）at concentrations of 0~80mg/L to the EPD system to analyze the mechanisms of PAHs tolerance by batch tests. The results indicated that under the stress of phenanthrene and anthracene, the EPD systems maintained a high accumulation rate of 86% for NO₂^--N and a removal capacity of 50% for PO₄^3--P. In the anthracene system, the microorganisms secreted more extracellular polymeric substances to protect themselves, while a greater enrichment of PAH-RHD GNF/R and PAH-RHD GPF/R genes was observed to enhance tolerance to PAHs in the phenanthrene system. The introduction of phenanthrene and anthracene significantly enriched denitrifying glycan bacteria and denitrifying phosphorus accumulating bacteria. The denitrifying activity of the EPD system acclimated with phenanthrene was（167.429±2.321）mgN/（gVSS⋅h）, and it still maintained a well phosphorus removal capacity under the stress of naphthalene and anthracene. The EPD system acclimated with anthracene maintained high NO₂^--N accumulation capacity under the stress of naphthalene and phenanthrene, with denitrifying bacterial activity at（220.137±0.575）mgN/（gVSS⋅h）. This study provides the theoretical support for the tolerance of EPD systems to low molecular weight PAHs and also proposes insights into enhancing the impact resistance of EPS system through technological interventions, which has significant importance for optimizing the operational effectiveness of EPD in wastewater treatment.

This paper takes the period from 2005 to 2022 as the examination period, and discusses the dynamic evolution law and spatial correlation characteristics of China's animal husbandry on the basis of re-measuring its carbon emissions and analyzing its current characteristics. The results show that the total amount of carbon emissions from China's animal husbandry in the study period has fluctuated, but the overall trend is declining, the carbon emission intensity has been in a continuous downward trend, only the inter-annual rate of decline is different, cattle and hog feeding is the key driver of carbon emissions from the animal husbandry. In 2022, the carbon emissions of the animal husbandry in each province and region were significantly different, and the top 10regions were mainly identified as core livestock production areas or grain production areas. The carbon emissions intensity of the animal husbandry in the interprovincial area was characterized by a distribution pattern of 'high in the northwest and low in the southeast'. The 30 provinces and regions were categorized into four types, such as those driven by cattle feeding and those driven by hog feeding, based on the composition of the carbon emissions of the animal husbandry in each region. During the study period, the carbon emission intensity of the animal husbandry as a whole, as well as that of cattle and sheep rearing, showed an obvious downward trend and the inter-provincial gap narrowed significantly; while the carbon emission intensity of hog rearing also declined, but the inter-provincial gap widened significantly. During the study period, the carbon emission intensity of China's animal husbandry has always had a significant spatial dependence, with low-low agglomeration as the main focus and high-high agglomeration as the secondary focus, and showing the characteristic of “the low is always low and the high is always high”.

This study utilizes panel data from 30 Chinese provinces from 2000 to 2021. We treat the carbon trading policy as a quasi-natural experiment, and apply a multi-period difference-in-differences method to systematically evaluate its impact on carbon emissions. The results indicate that: after the introduction of the carbon trading policy, the total carbon emissions in the pilot regions decrease by 13.2%, while carbon intensity and per capita carbon emissions fall by 21.3% and 17.2%, respectively. The carbon trading policy significantly reduces carbon intensity in the pilot regions; however, the impacts on total carbon emissions and per capita emissions are not significant. Carbon reduction through trading primarily relies on improvements in industrial structure, with weaker mediation effects from carbon trading prices, market activity, and low-carbon technology. There may be complementary and synergistic effects among different policies. Although carbon trading plays a positive role in promoting carbon reduction, its synergistic effects on SO₂, NO_x and PM_2.5 still need to be enhanced. These results provide important empirical support for understanding carbon trading policies and offer a scientific basis for refining the carbon trading system as well as guiding future adjustments and optimizations of carbon market policies.

This research aims to analyze the influencing factors of aquifer recharge management in the Sanjiang Plain, China, by utilizing Geographic Information System（GIS）and Analytic Hierarchy Process（AHP）to construct a suitability evaluation system for Agricultural Managed Aquifer Recharge（Ag-MAR）. The results indicate that areas with deeper groundwater levels are more suitable for recharge, accounting for approximately 20.2% of the total study area, while the region's dense river network provides substantial surface water resources. Additionally, the optimal recharge period is identified as spanning from mid-October to early November. This study provides a scientific basis for groundwater management and presents specific recharge recommendations to address the issue of groundwater over-extraction, thereby ensuring the sustainability of both agricultural production and ecological systems. The findings underscore the importance of Ag-MAR in promoting sustainable groundwater management practices in agricultural regions.

The hydro-chemical characteristics and trophic status of reservoirs are shaped by a combination of natural conditions and anthropogenic effects within the watershed. This study focuses on Xiaowan Reservoir（XW）and Danjiangkou Reservoir（DJK）to analyzes the main ions characteristics and spatial variations of nitrogen（N）and phosphorus（P）nutrients in their water bodies, we identify the primary sources of these ions and interprets the nutrient status of these karst reservoirs, along with the influencing factors. The results show that: The water chemistry of the karst reservoirs is governed by rock weathering, resulting in HCO₃·SO₄-Ca and HCO₃-Ca types for XW and DJK respectively; Both reservoirs exhibit high anthropogenic inputs of SO₄^2-and NO₃^-; In both reservoirs, nitrogen（N）and phosphorus（P）predominant exist in dissolved forms. While no carbon-limitation was observed,N-limitation is evident in XW and P-limitation in DJK, leading to a mesotrophic status in both reservoirs; The stoichiometric ratio of carbon（C）, nitrogen（N）, and phosphorus（P）are the primary factors influencing the comprehensive trophic level index（TLI）of the reservoirs. This is attributed to the karst hydrochemical background and high weathering rates; Under different N and P limiting conditions, the trophic status is affected by various factors, with the C to P ratio-sensitive to rock weathering, climate change, and anthropogenic inputs-emerging as a key determinant of water quality; To optimize the evaluation indices for assessing the trophic state and managing water quality in karst reservoirs under diverse hydrological conditions and functional roles, it is essential to analyze the effects of water chemical characteristics and stoichiometric ratios of biogenic elements on trophic status based on the analysis of nutrient limitations in water bodies.

A case study was conducted at Tianjin Airport by the research team, in which the predicted emissions using default parameters (recommended values) were compared with the results based on inputs that had been adjusted to real-world airport operations. A high spatial resolution (45m×45m) emission inventory was established in the airfield area to identify emission hotspots, and the results indicated that the daily emissions generated by all mobile sources at the airport based on recommended values were 2,320.01kg (NO_x), 12,919.90kg (CO), 199.36kg (SO₂), 76.83kg (PM) and 635.92kg (HC). After adjustment of inputs based on real-world airport operations, the emissions results were 1,982.65kg (NO_x), 722.25kg (CO), 157.27kg (SO₂), 70.48kg (PM) and 86.38kg (HC). The time between 08:00 to 09:00 (the departure peak at the airport) was identified as the period when the maximum total emissions across time of day occurred. Results of the spatial analysis showed that the emission hotspots were predominantly distributed as follows: for NO_x, near the end of the departure runway; for CO, the merging area of taxiways (which connect arriving and departing flights); for SO₂ and PM, the aprons with a larger number of arriving and departing flights; and for HC, both the merging area of connecting taxiways and the aprons with a larger number of flights. The top 20% of emissions were primarily from: for NO_x the take-off stage of aircraft; for CO, taxiing stage of aircraft; for SO₂ and HC, the ground support equipment in the parking position during the service stage and taxiing stage of aircraft; and for PM, ground support equipment at parking lots and service lanes.