Phytoremediation technology has been widely used for the remediation of heavy metals in soil due to its favorable environmental and ecological effects, but establishing a single phytoremediation technology can result in bottlenecks, such as a long cycle, low biomass, and difficulty in root absorption. At present, inoculation with microorganisms that could assist plants in their remediation of contaminated soils is attracting increasing attention. Therefore, in this study we selected ryegrass and Bacillus thuringiensis (SY) and analyzed the effects of SY inoculation on the growth of ryegrass, including the accumulation of Cd in ryegrass, changes in heavy metal forms, and the heavy metal content in rhizosphere soil, using pot experiments. The results indicate that SY inoculation promotes root growth and development of the ryegrass and the accumulation of cadmium in the plants. In addition, SY inoculation increased the levels of soil nutrients and the activities of soil urease, sucrase, and alkaline phosphatase. This study reveals that the use of SY improves the remediation efficiency of ryegrass for cadmium-contaminated soil, and supports the application potential of microorganisms in soil remediation technology.

In this study, biochar (BC), triple superphosphate (TSP), and TSP+BC amendments were utilized for remediation of Cd, Pb, and Cu co-contaminated agricultural soils. The toxicity characteristic leaching procedure (TCLP), the European Community Bureau of Reference (BCR), X-ray diffraction, and scanning electron microscopy-energy dispersive spectrometer techniques were employed to evaluate the effectiveness of the three types of amendments. After soil amendment, pH, heavy metal concentrations in TCLP extracts, and BCR speciation of heavy metals showed significant changes. The application of BC, TSP, and TSP+BC to co-contaminated soils slightly increased soil pH; decreased Pb, and Cu leachability in the TCLP extracts; and lowered the concentrations of the acid-soluble fraction of heavy metals. The application of TSP+BC mixture at the same dose as BC and TSP produced the greatest reduction in available heavy metal concentration. The optimum mass ratio of TSP to BC was 1:3. Overall, the TSP+BC mixture was highly effective in immobilizing Cd, Pb, and Cu in co-contaminated agricultural soils. The experimental results demonstrate that the rational application of the TSP and BC provides benefits of retrenching phosphorus resources, decreasing phosphorus pollution, and lowering the feed costs of debasing soil remediation treatments.

To seek a restoration plan for the safe use of agricultural land around mining areas, this study focuses on the regions around a mining plant in Huidong County, western Sichuan Province, affected by lead–zinc mining, and the precise remediation of heavy metal pollution through large-scale synthesis of iron silicate. In this study, we investigated heavy metal pollution in the vicinity of the mining area and proposed a treatment strategy using large-scale synthesis of iron silicate to mitigate this pollution. According to field investigation and sampling analysis, the collected soil samples contained excessive Cd, Pb, and Zn. Cd is a heavy metal related to lead–zinc mining. The planting of crops such as loquats and garlic with a high accumulation coefficient for Cd was found inappropriate for the research area. Instead, it was recommended to plant economically important crops like mangoes and peaches which had lower heavy metal accumulation. On the basis of field investigation, the study area was seriously polluted by heavy metals, among which Cd was 4.0 times higher than the standard of agricultural land. In order to accurately passivate excessive Cd, Zn, and Pb, iron silicate material was put into mass production. In situ passivation experiments showed that when the soil water content was between 25% and 20%, adding 4% silicate material could rapidly reduce the content of effective heavy metals in the soil and the heavy metal content of garlic and other cash crops in the research area by about 8%. After conducting a field investigation, it has been determined that the large-scale preparation of iron silicate can accurately repair soil contaminated by heavy metals in the vicinity of mining areas. In conclusion, iron silicate is capable of effectively reducing the pollution of heavy metals on agricultural land and facilitating the safe utilization of such land.

Crop production is threatened by both water scarcity and poor soil water retention in arid or semi-arid regions. At the same time, the industrial-scale accumulation of municipal sludge creates substantial environmental and resource pressures. The goal of this work was to recycle municipal sludge into a low-cost, environmentally friendly, and multifunctional sludge-based water-retaining material (SBWRM) for enhancing soil water retention capacity and nutritional status. Sludge was used as the primary raw material, and extracellular polymeric substances were extracted using a combined alkaline ultrasonic method. These extracts were then mixed with polyvinyl alcohol to prepare the sludge-based material. The water retention capacity of the material, as well as its effects on seed germination and plant growth in a planting substrate, were systematically evaluated. The results suggested that the SBWRM achieved a maximum water retention capacity of 18.7 times its own weight. The addition of 40% SBWRM effectively promoted ryegrass seed germination and plant height, increased soil moisture and pH value, and enhanced the nutrient contents of nitrogen, phosphorus, and potassium. The findings indicate that SBWRM can effectively enhance water conservation, soil quality, and nutrient supply, thereby providing a practical approach for utilizing sludge resources and supporting ecological restoration in agricultural systems.

Hydrological regime is widely recognized as the primary driver shaping riparian vegetation, yet its mechanistic links with taxonomic, functional, and ecosystem diversity under dam-regulated conditions remain insufficiently quantified. In this study, we quantified flow regime characteristics in the Three Gorges Reservoir (TGR). We identified five statistically distinct flow regime types using hierarchical clustering based on magnitude, duration, frequency, average flooding intensity, and rate of change. Significant differences among the five flow regime types were observed using one-way ANOVA with Tukey HSD post hoc tests (p < 0.05), particularly in magnitude, duration, flooding intensity, and rate of change, while flooding frequency showed no significant variation. Species richness was negatively associated with flooding duration but positively associated with hydrological conditions of milder flow regime types, especially during early and late growing seasons (April and September). Functional diversity increased along the flow regime gradient and exhibited a significant positive association with species richness. After statistical re-evaluation, only linear relationships were retained (p < 0.05). The results demonstrate that flow regime is a more reliable predictor of riparian vegetation zonation and functional diversity than flooding duration alone, emphasizing the role of hydrological variability in shaping ecosystem functioning within large regulated reservoirs.