Zhuofan Gao

Dissolved organic matter (DOM) plays a key role in shaping lake microbiomes and water quality, yet its spatial variability and regional links to microbial activity remain unclear. Using three-dimensional excitation–emission matrix and self-organizing map analysis on 38 samples from a human-impacted lake network in Hubei (affected by tourism, agriculture, and urban areas), this study clarifies DOM heterogeneity and its environmental connections. Microbial metabolic activity represented by total bacterial content (BC) and Escherichia coli (E. coli) activity was rapidly and automatically measured with a ColiMinder device. Random forest (RF) modeling and principal component analysis (PCA) were applied to identify key drivers of microbial activity and to clarify correlations between DOM characteristics and microbial activitiy. Results indicated that although DOM in all three sectors primarily originated from microbial activities during the flat-water period, Tuanhu (TH) exhibited a higher degree of DOM humification and a larger average relative molecular mass, reflecting stronger terrestrial source characteristics. RF analysis identified NH₄⁺ as the main predictor of both BC and E. coli levels, while total organic carbon (TOC) and total nitrogen (TN) were also important predictors. PCA further revealed clear differences in DOM composition across the lakes. DOM in TH was predominantly autochthonous, whereas DOM in Miaohu (MH) and Guozheng (GZ) was mainly of humic origin. This study adopts an integrated method combining rapid microbial detection, EEM and DOM–microbe correlation analysis to analyze human disturbances across segmented connected lakes in Hubei. It provides scientific support for targeted water quality management of human-influenced freshwater.

Conventional physicochemical parameter-based monitoring fails to provide real-time early warning of microbial risks in drinking water sources, highlighting the critical necessity to unravel the inherent associations between microbial activity and water quality dynamics. This study integrated a domestically developed microbial enzymatic analyzer with multivariate analyses to assess real-time microbial activity in a complex reservoir. Measurements of microbial indicators and physicochemical parameters were conducted at eight sites during dry and wet seasons, plus six months of continuous monitoring at a polluted tributary site. Key findings: (1) Water quality showed clear spatiotemporal variation, worse in the wet season than the dry season, with tributaries more polluted than mainstream, and downstream better than upstream; (2) Microbial activity exhibited spatial heterogeneity, with a significant positive correlation between E. coli and Enterococcus (EC); (3) Microbial activity responded to key water quality indicators, and both E. coli and EC correlated positively with NH₃-N. EC also correlated positively with TP. In summary, this study reveals a mechanism-based link between microbial activity and key water quality parameters, providing a theoretical foundation for a microbial-response-centered early warning model. This marks a shift from conventional reactive monitoring to proactive risk management for drinking water safety, offering a new paradigm with ecological indication and practical value.

To investigate the impact of periodic water-level fluctuations on soil microbial community structure in the riparian zone of the Three Gorges Reservoir Area, this study focused on the riparian zone at Zhangjiawan near the dam. Surface soil samples (0–20 cm) were collected in spring, summer, and autumn from three elevation gradients: below 160 m, 160–170 m, and above 170 m. Phospholipid fatty acid (PLFA) was employed to characterize the microbial community structure. The results indicated that microbial community distribution was significantly influenced by both elevation and season, with bacteria dominating community variations. In terms of elevation, the total microbial biomass and bacterial abundance were highest at the 160–170 m gradient, followed by the area above 170 m, and lowest below 160 m. Season and elevation exhibited a significant interactive effect on fungi. Seasonal patterns showed that total microbial biomass and bacterial abundance peaked in summer, whereas fungal abundance and the fungi-to-bacteria ratio were higher in autumn. In contrast, actinobacterial abundance remained stable across seasons. Soil organic carbon (SOC; 60.3%) was identified as the predominant environmental factor influencing microbial community structure, followed by total nitrogen (TN; 13.9%) and pH (2.4%). SOC was identified as the key driver of microbial community dynamics. These findings clarify the respective roles of water level fluctuation, seasonal variation, and environmental factors in shaping riparian microbial communities, providing critical baseline data and theoretical support for ecological protection and scientific management of the Three Gorges Reservoir Area.

This study introduces an innovative approach to fabricating a poly ether ketone (PEEK)‐based thin‐film nanocomposite (TFN) nanofiltration membrane. Ultrafine polydopamine (PDA) modified zeolitic imidazolate framework‐8 (ZIF‐8) nanoparticles were integrated into the polyamide (PA) layer through a process of interfacial polymerization. The impacts of PDA@ZIF‐8 nanoparticle loading on composite membranes were examined, and their separation performances with different solvents and small molecular organics with various molecular weights and charges were evaluated. The PDA modification is credited with inducing a thinner, less crosslinked PA layer, culminating in the formation of a selective barrier that is both loose and ultra‐thin, improving the separation capabilities of membranes. The TFN‐3 membrane, with a 0.01 wt% loading of PDA@ZIF‐8 nanoparticles, emerged as a standout, demonstrating notably enhanced hydrophilicity. The pure water and organic solvent permeances through the TFN‐3 membrane were remarkably enhanced, with recorded values of 6.19 ± 0.26 L h⁻¹ m⁻² bar⁻¹ for pure water and 3.44 ± 0.21 L h⁻¹ m⁻² bar⁻¹ for methanol. Furthermore, the TFN‐3 membrane showcased impressive molecular retention in ethanol solutions for compounds with a molecular weight cut‐off (MWCO) of 464 g/mol. The PEEK‐based TFN‐3 membrane also exhibited exceptional creep resistance, ensuring consistent performance during long‐term testing. In a 5‐day ethanol separation test, the TFN‐3 membrane maintained a Rose Bengal (RB) retention rate exceeding 99%, underscoring its stability and reliability. The newly developed PEEK‐based TFN membrane not only promises robust solvent resistance and stability but also delivers efficient separation and purification capabilities. It holds great potential for offering effective and sustainable solutions across a spectrum of industries, particularly in pharmaceutical production and chemical processing, where the separation, recovery, and purification of solvents are paramount.

Dye adsorption by magnetic modified biochar has now received growing interest due to its excellent adsorption performance and facile separation for recycling. In this study, nano iron oxide–modified biochar was fabricated via the successive hydrothermal-pyrolyzing method using Chlorella vulgaris (Cv) and FeSO₄·7H₂O as raw materials, and its adsorption on Rhodamine B (RhB) in aqueous solution was studied. Multiple techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), vibrating sample magnetometry (VSM) and X-ray photoelectron spectroscopy (XPS) were employed to comprehensively characterize the structure, morphology and physicochemical properties of the adsorbent. The as-synthesized nano iron oxide–modified biochar (CBC-Fe(II)) exhibited a large surface area (527.6 m²/g) and high magnetic saturation value (13.7 emu/g) to facilitate magnetic separation. Compared with CBC and CBC-Fe(III), CBC-Fe(II) exhibited superior adsorption ability towards RhB in aqueous solution, with a maximum adsorption capacity of 286.4 mg/g. The adsorption process of RhB onto CBC-Fe(II) was well described by the pseudo-second-order kinetic model and Langmuir isotherm model, indicating monolayer chemisorption behaviors for the adsorption system. Facile preparation, great adsorption performance and magnetic recovery properties endow CBC-Fe(II) to be a promising adsorbent for dye removal.