Jianbiao Peng

The Yangtze River Basin is a critical water supply region in China. To quantify the contributions of climate change and human activities to water resources across multiple temporal scales, this study focuses on actual evapotranspiration (AET), which directly influences water availability. Monthly runoff data from the Zhimenda Hydrological Station in the source region of the Yangtze River for the period 1982–2019 were analyzed using the Mann–Kendall (M-K) abrupt change test and the Bernaola–Galván (B-G) segmentation algorithm to identify the change point in runoff depth. The study period was subsequently divided into a baseline period and a post-change period. The ABCD hydrological model was employed to simulate monthly runoff variations during both periods, and the simulated results were used to calculate intra-annual (seasonal and monthly) AET. The Trend-Free Pre-Whitening Mann–Kendall (TFPW-MK) test was then applied to the AET series derived from the ABCD model to analyze temporal trends and intra-annual distribution characteristics. Finally, a multi-time scale Budyko framework was constructed to conduct attribution analysis based on AET data, quantifying the respective contributions of climate change and human activities to AET variation. The results indicate that: (1) The change point in the runoff series was detected in 2008. The Nash–Sutcliffe efficiency coefficients for both the baseline and post-change periods exceeded 0.88. (2) At the monthly scale, AET showed an increasing trend in January, February, July, September, November, and December. At the seasonal scale, AET exhibited a decreasing trend in spring and summer and an increasing trend in autumn and winter, though these trends were not statistically significant. Despite the varying directional trends observed across individual months and seasons, AET showed no statistically significant changes at either the seasonal or monthly intra-annual scale. (3) The intra-annual distribution of AET in the source region of the Yangtze River was highly consistent with precipitation patterns, showing significant synchronous variation. (4) Attribution analysis revealed that human activities played a dominant role in driving the observed trends in AET.

Climate change and human activities are significantly altering hydrological systems, intensifying extreme events such as hydrological drought patterns. These changes pose critical challenges for water sustainability, requiring a deeper understanding of prolonged hydrological droughts. Under the complex changing environment, hydrological drought in the Upper Yangtze River is becoming increasingly severe. Using monthly scale meteorological and hydrological data, this study quantitatively conducted an attribution analysis of hydrological drought in the Upper Yangtze River through a multi-method framework combining mutation analysis, a hydrological model, and machine learning. The results showed that: (1) the coupled model had higher precision and better applicability in a basin with more complex changing environments. (2) Climate change was the dominant factor for most months of monthly scale hydrological drought in the Wujiang, Jialing, and Upper Yangtze River Basins, while human activities were the main cause of hydrological drought in most months in the Tongtian River. (3) The dominant factor for seasonal hydrological drought in the Wujiang and Upper Yangtze River Basins was climate change. The seasonal hydrological drought in the Tongtian River and Jialing River basins was jointly affected by climate change and human activities.

This work harnesses the intrinsic reductive capacity of biochar-supported nanoscale zero-valent iron (nZVI@BC) under anoxic conditions, avoiding the environmental liabilities of in-situ advanced oxidation and enabling a synergistic adsorption-reductive transformation-in situ immobilization mechanism for tetracycline hydrochloride (TCH). The biochar (BC) matrix serves as an electron shuttle, unlocking efficient electron transfer from Fe(0) to TCH. This is evidenced by a distinct dual-to-single charge transfer resistance (Rct) transition (23.4 Ω) in electrochemical impedance spectroscopy and irreversible Fe(0) oxidation in cyclic voltammetry, contrasting sharply with the resistive oxide layers of pristine nZVI. Isotopic substitution experiments (D2O) further reveal a kinetic isotope effect, confirming the involvement of water‑derived surface‑bound active hydrogen (H*) as a supporting reductant. The nZVI-driven reduction is confirmed by LC-MS identification of a deoxygenated product (C21H19NO7). Critically, the Fe(II)/Fe(III) species generated during Fe(0) corrosion precipitate as amorphous iron (hydr)oxides, instantly immobilizing the transformation intermediates on the solid phase. This intrinsic solid-phase confinement ensures that the treated water exhibits no detectable acute toxicity (E. coli assay) and minimal iron leaching (90% of its initial capacity over five cycles. By integrating in-situ pollutant immobilization with ex-situ adsorbent regeneration, this work provides an effective and sustainable separation strategy for antibiotic remediation, achieving low-risk water purification in a closed-loop system.

Catalytic ozonation has been widely utilized in environmental applications, such as the removal of pharmaceutical active compounds (PHACs) from wastewater, due to its outstanding catalytic efficiency. To further enhance its performance and expand its practical application, ozone-based hybrid processes have been investigated, including ultraviolet radiation/ozonation, hydrogen peroxide/ozonation, ultrasonication/ozonation, and biological treatment/ozonation. Ozone degrades pollutants via two primary pathways: direct oxidation (via molecular ozone) and indirect oxidation (via reactive intermediates). Enhancing ozone decomposition into various reactive oxygen species (ROS), predominantly hydroxyl radicals, can significantly augment the degradation efficiency of pollutants. The surface adsorption and electron transfer processes of catalysts can promote ozone activation and decomposition into ROS to achieve the efficient degradation and mineralization of pollutants. Among catalysts, Mn-based catalysts have been extensively studied in past research. They have demonstrated exceptional performance when combined with other metals, such as Mn/Ce, Mn/Fe, and Mn/Co, etc., due to synergistic effects arising from bimetallic interactions. The inherent characteristics of catalyst supports may also influence the generation process of ROS. Choosing an appropriate support is conducive to promoting the uniform distribution of catalytic active sites on the catalyst surface and avoiding the agglomeration of metal particles, and it is also beneficial for the recovery and reuse of the catalyst. Furthermore, coupling catalytic ozonation processes with techniques like high-gravity technology, jet reactor systems, and micro–nano-bubbles can improve the utilization efficiency of ozone by exploiting gas cavitation effects. In this paper, we summarize the research progress in the degradation of PHACs using catalytic ozonation and discuss strategies for improving the mass transfer efficiency of ozone in water. Finally, the challenges and opportunities associated with applying catalytic ozonation in practical applications are also discussed.

Under the increasing pressures of land-based pollution and intensive coastal development, marine ecosystems are facing unprecedented challenges, highlighting the urgent need for enhanced protection and management of marine environmental quality. This study examines the spatiotemporal distribution and pollution risks of seven potentially toxic elements (Hg, Cd, Pb, Cr, As, Zn, and Cu) in the coastal waters of Bohai Bay, China, based on monitoring data collected from 2020 to 2023. Results show a significant decline in annual average concentrations of Pb (from 3.23 ± 1.11 μg/L to 0.10 ± 0.06 μg/L) and Hg (from 0.05 ± 0.02 μg/L to 0.01 ± 0.00 μg/L), reflecting effective pollution control measures. In contrast, Cu concentrations nearly doubled, rising from 0.90 ± 0.50 μg/L in 2020 to 1.98 ± 0.42 μg/L in 2023, while Zn exhibited a “V”-shaped fluctuation over the study period. Spatially, Zn, Pb, and Hg displayed pronounced clustering patterns, with coefficients of variation (CV) of 1.04, 1.49, and 1.17, respectively. The Pollution Load Index (PLI) decreased from 1.82 in 2020 to 0.94 in 2023, indicating an overall improvement in ecological quality. However, the Risk Index (RI) reached a maximum of 672.5 at Site 11 in 2020, with Hg and Cd contributing 49.6% and 22.7% to the total risk, respectively. Health risk assessment revealed non-carcinogenic risks (Hi) below the safety threshold (Hi < 1) across all sites. In contrast, carcinogenic risks (CR) ranged from 5.7 × 10⁻⁴ to 9.1 × 10⁻⁴, approaching the acceptable upper limit of 10⁻³, primarily due to dermal exposure to Hg and the high toxicity of Cd. Principal Component Analysis (PCA) suggested familiar sources for Hg, Pb, and Zn, whereas As appeared to originate from distinct pathways. Overall, this study establishes an integrated “pollution–ecological–health” assessment framework, offering scientific support for targeted pollution prevention and zonal management strategies in coastal environments.