This study analysed the spatiotemporal characteristics of dissolved oxygen (DO) concentrations upstream and downstream of sluices during dry and wet years, using data from three automated water quality monitoring stations and field measurements along the Huangjiang River in Guangdong Province. Multiple statistical methods were employed to identify the relative contributions of key influencing factors to DO variability across years under different precipitation conditions. Upstream DO concentrations were generally higher in dry years ((8.02±0.10) mg/L) than in wet years ((7.26±0.08) mg/L). In contrast, DO levels in the downstream tidal section increased from (4.45±0.10) mg/L (dry year) to (7.33±0.09) mg/L (wet year), primarily due to improved water quality. Periodic fluctuations were observed in both years, with higher DO levels during the flood season and lower levels during the non-flood season throughout the river channel. Influenced by the gate control and different external inputs, DO fluctuations upstream and downstream were driven by different factors. Rainfall and water temperature explained 44% to 87% of the DO variability upstream. While ammonia nitrogen, and COD_Mn were the most influential factors downstream, accounting for 53% to 75% of the variability. Furthermore, the “lacustrine” upstream section was especially sensitive to climate variations. In this area, the loss of phytoplankton biomass caused by stormwater runoff was a major factor contributing to DO difference during dry and wet years. While DO downstream is more easily influenced by water pollutants, especially the significant decrease in oxygen-demanding substances.

This study developed an improved export coefficient model by integrating rainfall and topographic correction factors to estimate non-point source nitrogen and phosphorus pollution loads and identify key pollution sources in the Ganjiang River Basin. The accuracy of the original and modified models was systematically compared, and correlation analysis was performed between nitrogen and phosphorus load intensity and monitored concentration data. The results demonstrated an increasing trend in both total pollution loads and load intensities from 2016 to 2020. Total nitrogen and total phosphorus exports increased by 15.99% and 16.37%, respectively, while corresponding load intensities rose by 15.89% and 16.85%. Spatially, the pollution distribution exhibited a characteristic north-high-south-low pattern with localized concentration, indicating higher contamination risks in downstream areas. Land use emerged as the primary source of nitrogen pollution, contributing 51.65% of total nitrogen exports, whereas livestock farming was identified as the dominant phosphorus source, accounting for 36.82% of total phosphorus outputs. The enhanced export coefficient model demonstrated significantly reduced relative errors compared to the original version. Statistical analysis revealed significant correlations (P<0.05) between annual average nitrogen or phosphorus concentrations and load intensities, confirming the improved model's superior accuracy. The refined model enables more precise assessment of watershed non-point source pollution, facilitates identification of major pollution sources, and supports targeted delineation of critical control zones, thereby providing valuable scientific support for non-point source pollution management and remediation strategies in river basins.

A multi-phase extraction technology was implemented to reduce the source of pollutants within a large retired chemical area in Shanghai, prevent further diffusion, and lower the health and ecological risks associated with the pollutants, while simultaneously analyzing the characteristics of NAPLs under the influence of multi-phase extraction. Through monitoring pollutants in the shallow groundwater across the site, changes in the spatial distribution of pollutants in the aquifer under extraction influence were characterized and ecological risks were assessed. The study indicated that the one-year multi-phase extraction project was significantly effective, with removal rates of pollutants in heavily contaminated areas reaching 64.56% to 99.26% at varying depths. A high degree of homogeneity and spatial autocorrelation was maintained among NAPLs prior to extraction, with correlation coefficients ranging from 0.26 to 0.72. The extraction process influenced the distribution and concentration of pollutants, resulting in changes in the correlations among them. The content and depth of DNAPLs in the site maintained a significant positive correlation, while LNAPLs exhibited a negative correlation. Under the extraction influence, the spatial distribution fitting of pollutants showed a substantial reduction in the central area and surrounding contamination halo, with the range of 1,4-dichlorobenzene pollution experiencing the largest decline, reducing the contaminated area by 91.98%. The assessment indicated that the proportion of high ecological risk points within the site significantly decreased post-extraction, and the multi-phase extraction comprehensively reduced the ecological risk of the site. However, some points of medium to high ecological risk still exist (primarily related to total petroleum hydrocarbon pollutants), which should be monitored and addressed in future remediation efforts.

Based on the InVEST model, Hierarchy of Needs Theory, and ecosystem service supply-demand analysis, we utilized Linkage Mapper and other tools to extract ecological sources, corridors, and pinch points in the Sichuan Basin from 2005 to 2020, following the least-cost path theory. The ecosystem service supply-demand relationship was analyzed to construct the ecological security pattern of the basin. Spatially, ecosystem service supply and demand in the Sichuan Basin exhibited a negative correlation. Despite an overall ecological surplus (supply exceeding demand), spatial mismatches between supply and demand intensified regional contradictions. From 2005 to 2020, the area of ecological sources in the basin was 68700km², 63900km², 63100km², and 64800km², respectively, presenting a “dense periphery-sparse center” ring-shaped distribution. The total length of ecological corridors across four periods increased continuously (6693.38km, 8342.29km, 8594.62km, and 14130.94km), forming a “periphery-connected, sparse-center, dense-east” network structure. Ecological pinch points were clustered at source junctions, while obstacle points were concentrated near fragmented source patches, particularly in the eastern parallel ridge-valley region. Integrating ecosystem service supply-demand dynamics and existing ecological security patterns, we proposed an optimized protection framework termed “Three Belts, Four Zones, and Five Cores”. Three Belts: East-west axial belts in the basin’s southern and northern regions, and a north-south axial belt in the eastern basin. Four Zones: Ecological security protection zone (eastern Sichuan), ecological restoration zones (western and northern Sichuan), and an ecological fragility recovery zone (central Sichuan). Five Cores: Key connectivity nodes in the southern basin and the eastern parallel ridge-valley area.

To elucidate the interaction mechanisms between iron-manganese minerals and antibiotics/antibiotic resistance genes (ARGs), enhance the understanding of their environmental degradation behaviors, and advance remediation technologies, this study systematically investigates the multifaceted degradation mechanisms of antibiotics by iron-manganese minerals. The mechanisms are explored through the following pathways: synergistic catalysis through surface Brønsted acid sites, Lewis acid sites, and hydroxyl groups promoting antibiotic hydrolysis; semiconductor-mediated photocatalytic degradation via electron-hole pair generation; direct oxidation by redox-active components such as Fe(III)/Mn(IV) coupled with activation of persulfate/hydrogen peroxide to yield reactive species for complete mineralization; concomitant radical-induced damage to ARGs through phosphodiester bond cleavage and base pair destruction, effectively inhibiting their horizontal transfer and evolution. The practical efficacy of iron-manganese minerals has been demonstrated in diverse environmental matrices including soils, aquatic systems, sludge, and livestock manure, with degradation efficiency dynamically regulated by pH, organic matter content, co-existing ions, and moisture conditions. Future research should prioritize establishing integrated databases mapping antibiotic-ARG co-degradation pathways and toxicity profiles, developing in situ dynamic characterization techniques for mineral interface reactions, engineering environment-adaptive mineral- based composite materials.

Soil contamination with phthalate esters (PAEs) is a worldwide environmental issue, and a stable and efficient functional microbial agent could be applied to achieve synergistic PAEs degradation. The review comprehensively compared various methods and pathways of microbial immobilization. The different factors on PAEs elimination such as mass transfer environment, substrate concentration, immobilization conditions, and strain combinations were demonstrated. The metabolic pathways of PAEs driven by enzymatic reactions of functional microbes were elucidated. The biological mechanisms of synergistic degradation of PAEs by microbial communities were clarified, and crucial future research areas may include the construction of microbial composite communities, optimization of immobilization carriers, and creation of microbial agent products. Compared to single-free bacteria, the immobilized PAEs-degrading microbial agents not only resist the interference of complex external environments, but specifically perform well on PAE degradation. In addition, immobilized microbial agents may positively promote crop growth.

This review summarizes the synthesis and regulation mechanisms of quorum sensing (QS) systems in Gram-negative and Gram-positive bacteria, focusing on key signalling molecules including acyl-homoserine lactones (AHLs), autoinducing peptides (AIPs), and autoinducer-2 (AI-2), as well as their applications in environmental remediation. The results demonstrate that QS-mediated regulation of bacterial collective behaviors primarily involves two critical processes: synthesis/release of signalling molecules and subsequent recognition-triggered behavioral responses. Notably, S-adenosylmethionine (SAM) serves as a common substrate for multiple QS signal biosynthesis pathways, potentially reflecting co-evolutionary adaptation between QS systems and bacterial coordination. Certain signalling molecules exhibit cross-kingdom functionality, not only adjusting conspecific bacterial behaviors but also mediating communication between phylogenetically unrelated bacteria and plants. Microbial communities leverage QS to synchronize population-level activities, optimize community architecture, and modulate synthesis of key degradation enzymes, thereby enhancing biofilm-mediated remediation efficiency. Finally, the development directions of QS-based microbial remediation technologies are discussed. The research results provide theoretical foundations and practical insights for studies on microbial remediation technologies.

To address the co-contamination of phthalic acid esters (PAEs) and cadmium (Cd) in agricultural soils of Guangxi province, a novel approach using immobilized functional microbial agent has been proposed. A composite microbial consortium, composed of three functional bacterial strains including Gordonia sp., Rhodococcus sp., and Bacillus sp., was developed with the ability to tolerate Cd and degrade PAEs. The microbial agent was immobilized on a thiol-modified montmorillonite-biochar composite carrier with optimized preparation conditions to enhance their remediation capabilities. The synergistic remediation efficacy of the agent on PAEs-Cd co-contaminated soils and the underlying mechanisms were elucidated. The results demonstrated that the composite microbial consortium achieved a degradation rate of 92.7% for total PAEs within 5days, while the carrier material exhibited a Cd saturation adsorption capacity of 15.2mg/kg. The optimal immobilization conditions were determined to be 30℃, with a bacteria-to-carrier ratio of 1:20 (V/M) for 1day. Under these conditions, the immobilized microbial agent achieved a degradation rate of 95.4% for ΣPAEs within 5days. When applied at a dosage of 1% to PAEs-Cd co-contaminated soils, the immobilized microbial agent resulted in 54.14% PAEs elimination and 37.06% decrease of exchangeable Cd after 50days. The immobilized microbial agent exhibited favorable synergistic remediation efficacy for PAEs-Cd co-contamination. The research findings provided a theoretical basis for the remediation of PAEs-Cd co-contamination in farmland soil of Guangxi and filled the theoretical gap in the control and remediation of PAEs-Cd co-contamination.

To investigate the effect of the Fenton-oxidized composting process on the removal of estrogens in manure, this study determined the concentrations of four estrogens—estradiol (E3), 17β-estradiol (17β-E2), bisphenol A (BPA), and ethinylestradiol (EE2)—in cow manure at various time points (0, 3, 12, 24, 48, 96, 192, 384, and 768hours) using the Fenton-oxidized composting process. The influence of Fenton's reagent and citric acid on estrogen removal during Fenton oxidation were also examined. Results demonstrated that after 3hours of treatment with Fenton's reagent and citric acid, the residual rates of E3, 17β-E2, BPA, and EE2in cow dung were 15.10%, 2.65%, 9.90%, and 11.44%, respectively, which were significantly lower than those observed in the non-oxidizing reagent treatment group. Following 32days of composting, the residual concentrations of E3, 17β-E2, and BPA fell below detectable limits, while the residual rate of EE2was only 2%. Additionally, seed germination rate analysis during the oxidized composting process revealed that the seed germination index of Brassica chinensis exceeded 50%, indicating that the composting products exhibited no apparent toxic effects on vegetable seeds. Consequently, the Fenton-oxidized composting technology can effectively accelerate the removal of estrogens from livestock manure, thereby facilitating its resourceful and harmless utilization.

The transmission of prions can induce the largely spread of transmissible spongiform encephalopathies, which pose a serious threat to animal and human health. Soil is a natural reservoir for prions. Prions can enter the soil through animal excretion, carcass decomposition, and bind to soil components. The binding of prions to different soil components varies significantly, and their effects are simultaneous and mutual, jointly influencing the spread of prions in the soil. On the one hand, the adsorption of soil particles and humic substances enhances their stability and persistence in the soil, reduces their bioavailability, and thus inhibits the spread of prions. On the other hand, montmorillonite and manganese ions can increase their activity and infectivity to a certain extent, thereby contributing to the spread of prions. The control of prions in the soil can be achieved through biotechnologies such as environmental prevention and control, enzyme treatment and composting technique, based on the improvement of their detection methods. In the future, the research on prions in the soil environment should take more into account the influence of the characteristics of soil compounds and native microorganisms on prions, so as to promote the development of in-situ prion degradation methods to control their spread. This work will provide theoretical support for the development of new technologies for soil prions control.