Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202508013
The Sanshenggong section of the Yellow River is a critical hydrological monitoring and control point, whose water quality directly affects the ecological safety and sustainable water resource utilization of the middle and lower reaches. This study analyzed water quality monitoring data from 2011 to 2024 using the Mann-Kendall test to identify abrupt change years, combined with single-factor evaluation and a fuzzy comprehensive evaluation method improved by CRITIC-entropy weight combination to systematically assess water quality evolution. The Mann-Kendall test identified 2013 and 2019 as abrupt change points, with non-significant improvement from 2013 to 2015 and significant improvement after 2016. Single-factor evaluation indicated that total phosphorus (TP) was the primary exceeding factor in 2011–2012, and its declining concentration drove the water quality upgrade from Class III to Class II in 2013. The CRITIC-entropy weight combination assigned the highest weight (28.96%) to permanganate index, whose decline was the core driver of water quality improvement. The improved fuzzy evaluation showed that the membership degree of Class III water dropped to zero in 2013, indicating stable improvement, but periodic rebounds in Class II membership suggested potential degradation risks. This study provides scientific evidence for ecological protection and high-quality development of the Yellow River Basin.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202605010
The underwater light environment is a critical limiting factor for the colonization of submerged macrophytes and the ecological restoration of shallow lakes. Previous studies rarely quantified the contribution of aquatic environmental factors to the water quality–underwater light–macrophyte relationship, nor did they comprehensively consider factor correlations or establish thresholds for macrophyte colonization. This study, conducted in a typical national wetland nature reserve (Hongze Lake), measured photosynthetically active radiation, light attenuation coefficient (Kd), euphotic depth (Zeu), water transparency (SD), total suspended solids (TSS), chlorophyll-a (Chl-a), total nitrogen (TN), and total phosphorus (TP). A simulation model for Kd was developed, spatial distributions of environmental factors were analyzed, and contribution rates to light attenuation were quantified. Results showed that the mean Kd was 10.31±3.76 m⁻¹, and the mean Zeu (0.53±0.24 m) was lower than the mean water depth (0.94±0.29 m), with a spatial pattern of shallower Zeu in the west and deeper in the east. TSS and Chl-a were the primary direct influencing factors, while TN acted mainly indirectly. To achieve effective macrophyte colonization under average water depth conditions, thresholds were determined: Zeu ≥ 0.94 m, SD ≥ 0.41 m, Kd ≤ 4.95 m⁻¹, and Chl-a ≤ 3.8 μg/L. These findings provide quantitative guidance for lake restoration and water quality management.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202605009
Reservoir CO2 emissions are a critical component of the global carbon cycle, yet existing prediction models often neglect reservoir size stratification, mixing data from large, medium, and small reservoirs. This study addresses this gap by constructing a training dataset exclusively for large and medium reservoirs in China and developing a neural network-based CO2 flux prediction model. The model revealed significant latitudinal zonation, with CO2 fluxes in southern low-latitude basins (e.g., Yangtze, Pearl) substantially higher than in northern high-latitude basins (e.g., Yellow, Songliao). Statistical analysis identified total phosphorus (TP) content as the strongest driver, exhibiting a positive exponential correlation with CO2 flux (p < 0.01). Reservoir age and latitude showed significant negative correlations, while physical parameters such as reservoir area, pre-impoundment submersion ratio, and average water depth showed no significant national-scale correlation. The study underscores the heterogeneity of dominant drivers across basins and proposes differentiated carbon mitigation strategies: for southern high-emission basins, controlling phosphorus inputs through wastewater treatment and restricting aquaculture; for northern basins, enhancing soil conservation to reduce carbon-rich sediment influx; and for new reservoirs, implementing vegetation clearance before impoundment and optimizing flood discharge schedules. These findings provide a theoretical basis for carbon emission characterization and support low-carbon management of large and medium reservoirs in China.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.1016/S1872-5813(26)60639-1
Ni/Al2O3 is regarded as one of the most promising catalysts for industrial CO2 methanation, yet it suffers from inadequate low-temperature activity and thermal sintering. To address these challenges, an Ni/CaO-ZrO2-Al2O3 catalyst with high low-temperature activity and robust high-temperature sintering resistance was developed by introducing Ca and Zr promoters. Under reaction conditions of 250 °C and a space velocity of 30000 mL/(g·h), the catalyst achieved a CO2 conversion of 96% and a methane space-time yield of 257.5 mmol/(g·h). In a 200 h aging test at 600 °C, the Ca-Zr dual-promoted catalyst exhibited a smaller increase in Ni particle size and less activity loss compared to the Ca-promoted counterpart. Characterization revealed that Ca and Zr promoters not only improve Ni dispersion but also enhance surface basicity, contributing to excellent low-temperature activity. Furthermore, Zr suppresses the transformation of Ca species into CaCO3 via solid-phase reaction under operating conditions, thereby inhibiting Ni sintering and ensuring high-temperature stability. This work provides a novel promoter design strategy for developing high-performance Ni-based catalysts for CO2 methanation.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3983-4
Refrigeration is essential for modern society, supporting applications from household appliances and industrial manufacturing to microelectronics and biopharmaceutical cold chains. Conventional refrigeration technologies are constrained by environmental impact and low energy efficiency, emphasizing the importance of developing sustainable alternatives. Solid-state caloric refrigeration, particularly electrocaloric (EC) devices, offers a promising route owing to their high cooling efficiency, rapid electric-field-driven response, and potential for miniaturization. Significant progress has been achieved in various EC device configurations. However, EC devices still face challenges in achieving large temperature spans, high cooling power, and effective integration for specific applications. This review systematically summarizes these developments, focusing on device design and performance enhancement. It elucidates the fundamental and shared design strategies, classifies EC devices into fluid-based heat-transfer type, solid-based heat-transfer type, and thermal-resistance-modulated heat-switch architectures, and analyzes representative device structures, performance metrics, and application scenarios. Finally, energy-recovery strategies and future optimization directions toward more efficient EC systems are discussed. This work provides a comprehensive reference for the design innovation and practical implementation of EC-based solid-state refrigeration technologies.