Bai-Lian Li

The Middle Route of the South-to-North Water Diversion Project (SNWD-MR) serves as a strategic infrastructure critical to safeguarding water security in Northern China. Traversing complex geographical units, the project is perpetually exposed to long-term risks of land subsidence. Conventional Interferometric Synthetic Aperture Radar (InSAR) monitoring is hampered by waterbody isolation, causing spatial discontinuities in the retrieved deformation fields; furthermore, relying solely on deformation metrics fails to comprehensively quantify multidimensional risks. To address these issues, this study proposes an integrated assessment framework that couples time-series InSAR observations with the Analytic Hierarchy Process-Fuzzy Comprehensive Evaluation (AHP-FCE) model. To specifically mitigate the challenge of waterbody isolation, we developed a connectivity-aware multiscale down-sampling phase unwrapping strategy. By exploiting cross-canal bridges to construct a spatial connection network, a highly accurate, spatiotemporally continuous deformation field across the entire alignment was successfully reconstructed. Using the derived deformation field as the core dynamic indicator, an AHP-FCE model integrating hydrogeological features and human perturbations was constructed. A complementary evaluation process comprising sensitivity analysis and an internal physical consistency assessment was subsequently implemented. The results demonstrate that (1) the proposed algorithm effectively resolves the spatial discontinuity issue of the cross-canal deformation fields, reducing the deformation-velocity RMSE from 7.9 to 5.7 mm/y, corresponding to an approximately 27.8% reduction in RMSE relative to the traditional Minimum Cost Flow (MCF) method; (2) land subsidence along the alignment exhibits prominent spatial heterogeneity, with the northern Henan and southern Hebei sections identified as very-high-risk zones; and (3) InSAR deformation magnitude and the groundwater elevation indicator emerge as the most influential factors in the modeled risk distribution. Overall, this study expands conventional deformation monitoring into a systematic, quantitative risk assessment framework, thereby providing scientific insights and theoretical support for the early warning of geo-hazards and the smart operation and maintenance of large-scale water diversion projects.

Particulate organic matter (POM) is a key component of aquatic organic matter. This study employed stable carbon isotope (δ¹³C) analysis and the Iso-Source mixing model to investigate the seasonal and vertical sources of different POM size classes in the Danjiangkou Reservoir. Results showed that smaller-sized POM (Pico- and Nano-POM) had more negative and narrower δ¹³C ranges (-35.02‰ to -21.33‰) compared to larger sizes (Micro- and Net-POM: -35.87‰ to -15.12‰). Spatiotemporally, phytoplankton and C3 plants were the primary sources for smaller POM (contributing 58.04%), with phytoplankton being dominant. For larger POM, phytoplankton and C4 plants contributed more significantly (56.14%). The coefficient of variation (CV) for phytoplankton was significantly lower in spring and summer than that in autumn and winter across all POM size classes. The lowest CV was observed for smaller POM, indicating that the source of smaller POM was more stable. Vertically, δ¹³C of smaller POM correlated significantly with TOC (p < 0.01), while that of larger POM correlated with NO3--N, NH4+-N, and TN (p < 0.05). This study reveals the source characteristics and environmental responses of different POM size classes in a subtropical deep-water reservoir, providing a scientific basis for understanding aquatic carbon cycling.

This study investigates the feeding behavior and ecological role of Craspedacusta sowerbii in the Danjiangkou Reservoir, a crucial freshwater source in central China. Through in situ cultivation, microscopic examination, and amplicon sequencing analysis, we identified the primary food sources of C. sowerbii within the reservoir’s aquatic food web. Our results indicate that C. sowerbii predominantly consumes zooplankton, specifically rotifers, copepods, and cladocerans, while phytoplankton is ingested less frequently and often remains undigested. Amplicon sequencing data further confirms that the prey composition of C. sowerbii is enriched in zooplanktonic communities compared to phytoplanktonic communities. Our findings suggest that C. sowerbii plays a significant role in regulating plankton populations and shaping the planktonic community structure in the Danjiangkou Reservoir, thereby contributing to the ecosystem’s functions and trophic dynamics. This study enhances our understanding of the feeding ecology of C. sowerbii and highlights its potential as a bioindicator species for assessing freshwater ecosystem health and monitoring water quality.

Microplastics (MPs) and heavy metals are commonly present in soil at significant concentrations and can interact in complex ways that pose serious threats to environmental and ecological systems. The effects of combined contamination by different types of heavy metals and microplastics on plants, as well as on soil microbial communities and their functions, remain largely unexplored. In this study, a series of pot experiments was conducted to investigate the effects of composite contamination involving two heavy metals (Cd and Pb) and two types of microplastics polylactic acid (PLA) and polybutylene succinate (PBS) at varying concentrations (0.1% and 0.5%, w/w). The impacts on water spinach (Ipomoea aquatica) growth and heavy metal accumulation were evaluated, and the rhizosphere bacterial and fungal community structure and diversity were analyzed using high-throughput sequencing. The presence of Cd, Pb, and microplastics significantly inhibited the growth of water spinach, reducing both its length and biomass. Under combined microplastic–heavy metal contamination, phytotoxicity increased with rising concentrations of PLA and PBS. Microplastics were found to alter the mobility and availability of heavy metals, thereby reducing their accumulation in plant tissues and decreasing the levels of available potassium and phosphorus in the soil. Furthermore, microplastic–heavy metal interactions significantly influenced the composition and diversity of soil microbial communities, leading to an increased abundance of heavy-metal-tolerant and potential plastic-degrading microorganisms. A strong correlation was observed between microbial community structure (both bacterial and fungal), soil physicochemical properties, and plant growth. Functional predictions using PICRUSt2 suggested that the type and concentration of microplastics significantly affected rhizosphere microorganisms’ metabolic functions. In conclusion, the present study demonstrates that combined microplastic and heavy metal contamination exerts a detrimental effect on soil nutrient availability, resulting in alterations to soil microbial community composition and function. Furthermore, this study shows that these contaminants can inhibit plant growth and heavy metal uptake. The findings provide a valuable contribution to the existing body of knowledge on the ecotoxicological impacts of microplastic–heavy metal composite pollution in terrestrial ecosystems.

With the rapid development of industry and agriculture, soil heavy metal contamination has become an important environmental issue faced today and has gradually attracted widespread attention. Finding a cheap, widely available, and biodegradable material that can promote crop growth and stabilize heavy metals has become a research focus. Crop straw biochar, due to its high specific surface area, rich surface functional groups, and high cation exchange capacity (CEC), has shown good effects on the remediation of inorganic and organic pollutants in the environment. This article reviews recent research on the use of crop straw biochar for soil heavy metal contamination remediation, providing a detailed analysis from the preparation, characteristics, modification of crop straw biochar, mechanisms for reducing the toxicity of heavy metals in soil, and its application and risks in remediating heavy metal-contaminated soils. It also comprehensively discusses the potential application of crop straw biochar in the remediation of heavy metal-contaminated soils. The results show that crop straw biochar can be used as a new type of immobilizing material for the remediation of heavy metal-contaminated soils, but there are issues with the remediation technology that needs to be optimized and innovated, which poses challenges to the widespread application of crop straw biochar. In the future, efforts should be strengthened to optimize and innovate the application technology of crop straw biochar, conduct research on the remediation effects of cheap modified crop straw biochar and the co-application of crop straw biochar with other immobilizing materials on heavy metal-contaminated soils, and carry out long-term monitoring of the effects of crop straw biochar in soil heavy metal remediation in order to achieve the goal of ensuring food safety and the rational use of solid waste.

The concept of a geometric series (GS) plays an important role in mathematics. However, it has been neglected in describing biological size series. Herein, we show that a GS describes the nonreproductive (perianth) parts of the flowers of four Magnoliaceae species and two Rosaceae species and the leaves of 60 Alangium chinense and 60 Shibataea chinensis shoots. The sorted areas of floral parts and leaves formed a sequence that was fitted by a GS with the mean of the quotients of two adjacent members in the sequence as the common ratio of a GS. The mean absolute percent error (MAPE) was used to measure the goodness of fit of each GS. Over 99.7% of the MAPE values (371 out of the 372 tested flowers) were less than 10%, and over 97.8% of the MAPE values were less than 5%. Likewise, over 77.5% of the MAPE values (93 out of the 120 tested shoots) were less than 10%, and over 35% of the MAPE values were less than 5%. These analyses provide empirical evidence that the GS exists in nature, and confirm the usefulness of a classical algebraic formula for the study of plant developmental biology.

With the rapid development of industry and agriculture, soil contamination has become a significant environmental issue, and the heavy metal contamination of soils is an important part of it. The main methods for the remediation of heavy metal-contaminated soils include physical methods, chemical methods, biological methods, and combined remediation methods have been proposed as research deepens. However, the standards and evaluation methods for the remediation of heavy metal-contaminated soils are still not well-established. This article discusses the sources and contamination status of heavy metals in soils, the advantages and disadvantages of remediation technology for heavy metal-contaminated soils, remediation standards, and post-remediation evaluation methods. It also proposes scientific issues to be addressed in future research and provides an outlook on future development, hoping to assist in subsequent remediation studies of heavy metal-contaminated soils.

Rural domestic sewage, originating from human activities that involve the extraction and utilization of natural resources, is an inherent component of the ecological cycle in nature. Therefore, its disposal methods should align and harmonize with the laws governing nature’s evolutionary processes. This study conducted a comprehensive investigation on the domestic sewage facilities in representative villages located within the water source protection area of the middle route of the South-to-North Water Diversion Project. Taking Village A’s domestic sewage treatment station as a case study, an analysis was performed to assess its operational status and identify existing issues. The consideration of rural domestic sewage treatment should encompass factors such as the generation and discharge of household wastewater, the characteristics of water quality, discharge regulations, the natural and social environment, as well as post-completion operations and maintenance modes. We also proposed source reduction measures for the reuse of gray water in domestic sewage treatment in Village A, along with integrated treatment approaches involving biochemical treatment, landscape integration, and farmland irrigation for black water. These measures not only achieve effective treatment outcomes but also foster harmonious coexistence between humans and nature. Moreover, they align with the principles of ecological civilization while considering rural revitalization and promoting green agricultural development.

The quartz sand-enhanced coagulation (QSEC) is an improved coagulation method for treating water, which uses quartz sand as a heavy medium to accelerate the sedimentation rate of flocs and reduce the sedimentation time. The factors that influence the QSEC effect and can be controlled manually include the quartz sand dosage, coagulant dosage, sewage pH, stirring time, settling time, etc., and their reasonable setting is critical to the result of water treatment. This paper aimed to study the optimal conditions of QSEC; first, single-factor tests were conducted to explore the optimal range of influencing factors, followed by response surface methodology (RSM) tests to accurately determine the optimum values of significant factors. The results show that the addition of quartz sand did not improve the water quality of the coagulation treatment, it took only 140 s for the floc to sink to the bottom, and the sediment volume only accounted for 12.2% of the total sewage. The quartz sand dosage, the coagulant dosage, and sewage pH all had a significant impact on the coagulation effect, and resulted in inflection points. A QSEC-guiding model was derived through RSM tests, and subsequent model optimization and experimental validation revealed the optimal conditions for treating domestic sewage as follows: the polyaluminum chloride (PAC) dosage, cationic polyacrylamide (CPAM) dosage, the sewage pH, quartz sand dosage, stirring time, and settling time were 0.97 g/L, 2.25 mg/L, 7.22, 2 g/L, 5 min, and 30 min, respectively, and the turbidity of the treated sewage was reduced to 1.15 NTU.