Red mud (RM) was selected as the Fe source and orange peel (OP, pH=3.0~4.9) as the carbon source, RM@OPB composite was prepared through impregnation-pyrolysis method. The regulation of red mud alkalinity by orange peel and the influencing factors were analyzed. The catalytic performance of RM@OPB in activating PMS for IPM degradation was investigated as well. The mechanism of IPM degradation in the RM@OPB/PMS system was further explored through the combination of HPLC/MS analysis, active species quenching experiments, fluorescence spectroscopy, electron paramagnetic resonance (EPR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) of the pre-post-reaction of RM@OPB. Finally, the ecological toxicity of IPM and its intermediates was predicted using the Ecological Structure Activity Relationships (ECOSAR) software. The results demonstrated that orange peel co-impregnation effectively regulated the alkalinity of red mud, with the leachate pH decreasing from 11.0 to 7.27, at impregnation time and m_RM: m_OP of 24h and 1:2.5, respectively. During the pyrolysis, reductive gases generated from orange peel facilitated the transformation of Fe₂O₃ in RM into Fe₃O₄ and Fe⁰, magnetic RM@OPB materials was manufactured. Notably, RM@OPB-800exhibited effective catalytic performance for IPM degradation, with the degradation of 8mg/L IPM achieving 96.5% in 60min (k=0.065min^-1), under the experimental conditions of 0.5g/L RM@OPB-800, 1.0mmol/L PMS, and initial pH=6.7, respectively. Singlet oxygen (¹O₂) was identified as the dominant reactive species in the RM@OPB-800/PMS system. IPM degraded mainly through side-chain amide hydrolysis and oxidation, dehydrogenation, deiodination, and hydroxyl addition, with 12intermediates generated. ECOSAR analysis confirmed no highly toxic intermediates were formed. The findings can provide some critical insights into the resource utilization of red mud.

Food waste with different ratios of meat, fruits and vegetables was stored at 10~25℃ and 50% relative humidity for 48h in an environmental climate simulator to monitor the emission patterns of odors, identify the major odors, and explore the odors prevention and control strategies for the storage of household food waste in the community. The main odors from the short-term storage of household food waste were monitored to include the oxygenated compounds acetaldehyde and ethanol (combined odor contribution of 0.8% to 99.6%), sulfur-containing compounds (methyl sulfide, methyl mercaptan, and dimethyldisulfide), the alkanes 2-methylbutane and pentane, and α-pinene. The proportion of fruits and vegetables and meat significantly affected the intensity and relative composition of the odor emissions (differences between groups < 0.05). These two types of substances inhibited the decomposition of C-containing organic substances such as effective saccharides in food waste, but promoted the conversion of sulfur-containing organic substances to a certain extent, thus facilitating the formation and release of acetaldehyde and the three types of sulfur-containing compounds that had a greater impact on the odors, and the 48% FV (Fruit and Vegetable, hereinafter the same)-20.2% M (Meat, hereinafter the same) and 67% FV-3.6% M group rich in meat or fruits and vegetables were stored for 12~48h, and the theoretical odor concentration reached 38.7~68.1 and 83.7~205.3kg^-1 HFW (Household Food Waste, hereinafter the same) respectively, which were 5.5~9.4 times and 12.4~29.5 times higher than that of the food waste of 56% FV-4.9% M group under the same storage conditions. For the scenario of the community's multi-site unorganized emission of odorous air, the odor prevention and control can be performed according to the source and source of the odor release. Odor prevention and control can be carried out in accordance with the joint idea of source reduction, propagation prevention and control, and end reduction and purification.

A heavy soda saline soil was seleeted and rice was cultivated rice by potting method without applying organic fertilizers as a blank control (CK) to study the effects of application of common organic fertilizer (M0), 1% biochar loaded nano Fe₃O₄ (BC-Fe₃O₄ NPs) added composted organic fertilizer (M1) and 1% biochar loaded iron nanoparticles (BC-FeNPs) added composted organic fertilizer (M2) on the effects of soil physicochemical properties, nutrient effectiveness, enzyme activity and bacterial community changes. The results showed that the soluble salt content was significantly reduced by 23.31% (P<0.05) in M2treatment compared with M0. Compared with M0, the application of iron-rich organic fertilizer increased the total organic carbon content of soda saline soil by 4.95%. Compared with M0, the application of M2 significantly increased the content of Fe-bound organic carbon (Fe-OC) by 66.92%. Compared with CK, organic fertilizers increased soil quick-acting potassium and quick-acting phosphorus contents by 262.51%~521.28% and 222.99%~311.85%, respectively. Compared with M0, M2 treatment significantly increased the activities of sucrase, catalase and alkaline phosphatase, as well as the abundance and diversity of soil bacterial communities, and the relative abundance of Aspergillus, Bacteroidetes and Actinobacteria in the soil. The relative abundance of the above bacterial phyla was positively correlated with the fast-acting nutrient content of saline soil. Therefore, 1% BC-FeNPs composted organic fertilizer can significantly reduce soil soluble salt content, significantly increase total organic carbon content by promoting Fe-OC formation, and increase the abundance and diversity of bacterial communities, which is conducive to the fertilization of heavy soda saline soils.

The present study focused on the oxidative fixation of As(Ⅲ) by Fe(Ⅱ)-containing minerals in coordination with low molecular weight organic acids (LMWOA) (such as oxalic acid (OA), citric acid (CA), gallic acid (GA)) to generate reactive oxygen species (ROS). Siderite (FeCO₃) was utilized as the test mineral to investigate the capacity of FeCO₃-LMWOA complexes in adsorbed and co-precipitated states for As(Ⅲ) oxidation, and to analyze the generation of hydroxyl radicals (·OH) and the morphological changes of Fe during the oxidation process, as well as the effects of radical quenchers and C/Fe molar ratio on As(Ⅲ) oxidation and As(T) immobilization. The results demonstrated that adding 0.05~0.5mmol/L LMWOA enhanced the oxidation of As(Ⅲ) by siderite, with the order of GA>CA>OA, and the removal rate of As(Ⅲ) in the presence of GA was up to 80%. For the adsorbed and co-precipitated complexes, the oxidative capacity was enhanced by increasing C/Fe, and the co-precipitated FeCO₃-CA complex exhibited the highest removal efficiency of As(Ⅲ), reaching 92.1%. The free radical quencher methanol and NBT exhibited obvious inhibition on As(Ⅲ) oxidation, which proved that the main active substances for oxidizing As(Ⅲ) were and ·OH. The ability of different LMWOA to compete with As(Ⅲ) for ·OH was different, among which the co-precipitated FeCO₃-GA complex had the highest OC mineralization rate of 72.2%, and the main reason for the OC loss was the oxidation by ·OH. SEM and XRD analyses showed that siderite was transformed to hematite after reaction. This study not only reveals the synergistic mechanism between Fe(II)-containing minerals and LMWOA in As(Ⅲ) oxidation, but also provides new perspectives and strategies for the environmental management of arsenic pollution.

From the perspective of water quality-algae coupling, this study investigates the evolution of water quality and algal responses in the upper Xin'an River Basin in Anhui Province from August 2022 to April 2023. Multivariate statistical analyses identified the key drivers of water quality changes, and the relationships between water quality characteristics and algal indicators were explored. A composite algal indicator was developed to serve as an indicator of water ecological health, which includes [algal turbidity (AT) and algal dominance index (ADI)], elucidating its mechanisms in water quality assessment. Furthermore, a conceptual model integrating water quality and algal responses was proposed for comprehensive water quality identification. The results show that: (1) Water quality in the study area was primarily classified as Category Ⅲ (67.9%), with an average water quality index (WQI) of 81.61 (ranging from 55.42 to 90.83), signifying good quality overall. However, significant deterioration occurred between February and April 2023, with the WQI dropping to 76.09, highlighting the need for improved identification and protection measures. (2) Water temperature (WT), dissolved oxygen (DO), and nutrient concentrations were the primary factors driving water quality changes, with Spearman correlation coefficients reaching 0.72 (P≤0.01). (3) AT and ADI were effective composite indicators in rapidly identifying water quality degradation and ecosystem health. (4) The conceptual water quality identification model, constructed based on sensory characteristics, organic matter characteristics, and algal response, addresses the limitations of existing water quality standards, which often overlook biological indicators and degradation processes. These findings provide a scientific basis for identification and protecting the aquatic ecological environment of the Xin'an River Basin and offer insights into improving and innovating traditional monitoring systems.

Groundwater Dependent Ecosystems (GDEs) have played a vital role in maintaining ecological balance and providing ecological services, but they are facing increasingly severe threats under environmental changes. The identification and assessment of GDEs have been the basis for their monitoring, management, and protection. In this paper, the development, classification, delineation, and research methods for the identification and assessment of GDEs were reviewed. The framework of GDE identification and assessment models was summarized. The application of geospatial technologies, with GIS as a typical tool, and remote-sensing data provided by Landsat, Sentinel, MODIS, etc., in the identification of GDEs was explored. The current research limitations and future directions were put forward. The research on the identification and assessment of GDEs has evolved from using single determination methods, such as water level monitoring and isotopic analysis, to a comprehensive approach that integrates multiple data sources, including hydrogeological data, ecological indicators, and meteorological data. The representation of results has also shifted from traditional classification algorithms to the use of machine-learning-coupled algorithms, such as random forest models. However, how to accurately identify the spatial distribution of GDEs, precisely monitor their dynamic changes, and improve adaptive management strategies remain urgent issues to be resolved. In the future, theoretical innovation in the methodological system for GDE identification and assessment should be promoted. Innovation in methods should be achieved by integrating multi-source data, and technological innovation should be realized by exploring the application of deep-learning algorithms and the integration of artificial intelligence, so as to enhance the management level and efficiency of protection and restoration of GDEs.

In this study, microcosm experiment containing Vallisneria spiralis and La-modified attapulgite (LMA) was conducted to investigate the role of submerged macrophytes roots in controlling sediment phosphorus (P) release through the combined application of submerged macrophytes and La-modified clay. The dynamic variations of rhizosphere P and microenvironment were systematically analyzed using diffusive gradients in thin films (DGT), high-resolution dialysis (HR-Peeper), and 16S rRNA amplicon sequencing techniques. The results showed that the combined application of LMA and Vallisneria spiralis reduced the concentrations of soluble reactive P (SRP), DGT-labile P, and mobile forms of P (Mobile-P) in the sediment-porewater by 12.16% to 62.72%, 33.33% to 38.46%, and 3.66% to 10.53%, respectively, compared to the sole use of LMA. From day 7 to day 45, significant increases were observed in the total length, surface area, volume, root tip numbers and organic acid secretion of Vallisneria spiralis roots. Root-release oxygen enhanced the dissolved oxygen concentration and oxygen penetration depth at the sediment-water interface by 1.16-fold and 3.42-fold, respectively, shifting the dominant rhizosphere microbial communities from P-solubilizing bacteria such as Thiobacillus to aerobic bacteria such as Sideroxydans. Mantel test and partial least squares path modeling (PL-PM) analysis further revealed that organic acids secreted by Vallisneria spiralis roots accelerated the mineralization of organic P in the sediment, thereby enhancing OP absorption and utilization by the roots. Additionally, root-released oxygen promoted the proliferation of iron-oxidizing bacteria, which continuously oxidizing Fe²⁺ to Fe³⁺ in the porewater. This process immobilized SRP in the form of iron-bound P (Fe-P), effectively inhibiting P release from the porewater. This study provides novel insights that deepen the understanding of the mechanisms through which La-modified clay and submerged macrophytes jointly regulate the release of endogenous P in eutrophic lakes.

In the circumstance of global change, studying the dynamic changes of vegetation and the factors that influence it holds immense practical significance to monitor the quality of the regional ecological environment and improve the structure and function of ecosystems. In this study, the Theil-Sen Median trend analysis along with Mann-Kendal was used to characterize the overall change trend of vegetation ecology across the Yangtze River Delta based on the vegetation ecological quality index (VEQI) time series data (2000~2023). Then, the coefficient variation method was utilized to evaluate the stability in VEQI from 2000 to 2023. The geographic detector model was used to explain the natural and human activities driving mechanism of VEQI change. The results demonstrate that: The overall VEQI values in the Yangtze River Delta area showed a stage upward trend, with an increasing rate of 0.29a^-1. The upward trends observed in the VEQI indicated an enhancement in the ecological environment of the investigation area; The area whose VEQI increased was much larger than the area whose VEQI decreased. The area with improved VEQI accounted for 82.61% of the total area while the vegetation degradation areas for only 15.04%. The VEQI of study area owned a better stability, with low and relatively low fluctuation areas accounting for 54.66% and 15.99% of the area, respectively. The VEQI spatial variation primarily affected by a range of variances in natural phenomena and human activities, whereas spatial heterogeneity was mainly driven by factors such as landform type, elevation and slope. The improvement in the explanatory power of anthropogenic factors for spatial heterogeneity when combined with natural factors was significant. The research results aim to offer guidance for the execution of vegetation restoration initiatives and the establishment of policies for the preservation of the ecological environment in the upstream region of the Yangtze River Delta.

Based on Landsat and socio-economic data in the Northeast region from 1990 to 2023, this paper analyses the spatio-temporal characteristics of arable land ecological security using ecological footprint and ecological carrying capacity indexes, and explores the influence mechanism using geographic weighting model. The result show that: The per capita arable land ecological footprint increased from 0.135hm² per person to 0.145hm² per person, the per capita arable land ecological capacity decreased from 0.115hm² per person to 0.095hm² per person, and the per capita arable land ecological deficit increased from 0.16hm² per person to 0.058hm² per person. Farmland yield indicators show a decreasing trend, while indicators of ecosystem pressure on arable land show an increasing trend, and overall ecological security tends to improve. The impacts of natural resource on arable land ecological security shows a decreasing trend, while geographical location, socio-economic and regional policies show an increasing trend. This study is of reference value for the rational use of arable land resources and the sustainable development of ecological security.

Based on land remote sensing monitoring data from 2000 to 2023, this study employed geospatial models to quantitatively analyze the spatiotemporal evolution of land use functions in the upper reaches of the Yangtze River Economic Belt. In addition, a targeted analysis was conducted on the key influencing factors. The results indicate a continuous increase in the area allocated to living functions, whereas areas associated with production and ecological functions have declined. The spatial distribution of production functions exhibits a distinct pattern of being higher in the north and lower in the south, with significant spatial clustering of high and low-value regions. The distribution of living functions alternates between high and low from north to south and decreases from surrounding plains toward mountainous areas. Ecological function levels are significantly correlated with topography and geomorphology, showing pronounced spatial differentiation. The primary influencing factors include both natural and socio~economic variables, among which population growth, economic development, agricultural technology, and agricultural efficiency collectively drive the spatiotemporal evolution of the "production-living-ecological" land use functions. The findings provide valuable insights for regional land use planning and coordinated development strategies.