The middle reaches of the Yangtze River are important bases for high-tech, advanced manufacturing, and modern service industries in China, as well as a demonstration area for the coordination of economic and ecological construction, which plays an important role in the ecosystem carbon cycle. With the steady progress of social and economic development and urbanization, the supply capacity of ecosystem services has sharply decreased, and the carbon cycle mechanism has changed, further reducing the sustainability of regional ecosystem services. In this study, carbon storage in the middle reaches of the Yangtze River was estimated from 2000 to 2020 based on the InVEST model, and the temporal and spatial evolution characteristics of carbon storage in the middle reaches of the Yangtze River were summarized using the coefficient of variation and spatial autocorrelation. The coupled InVEST-PLUS model was used to simulate the carbon storage characteristics of the middle reaches of the Yangtze River under natural development, ecological protection, cultivated land protection, and urban development scenarios in 2035. The results show the following: (1) The main land-use types in the middle reaches of the Yangtze River are cultivated and forest land, and the land-use types in the study area show the characteristics of “two increases and four decreases” in the past 20 years. (2) The carbon storage level in the middle reaches of the Yangtze River has decreased by 83.65 × 10⁶ t in the past 20 years (approximately 1.16%). The coefficient of variation showed that the carbon storage level in the middle reaches of the Yangtze River was high, with the fluctuating area accounting for 8.79% of the total area. The results of local spatial autocorrelation show that the high-value areas of carbon storage are mainly distributed in the west and southeast of the study area, and the low-value areas are mainly distributed in the middle of the study area, exhibiting characteristics of “high values surrounding low values” in space. (3) The simulation results of carbon storage in the middle reaches of the Yangtze River in 2035 showed that the ecological protection scenario was better than the other scenarios in terms of the mean level, functional performance, and patch presentation.

To understand the characteristics of the pollution risk of potentially toxic elements (PTEs) at a rare and precious metal mining site in Guangxi and to provide scientific evidence for the comprehensive evaluation and soil remediation of PTE pollution at the site, the Cd, As, Co, Cu, Cr, Ni, Pb, and Zn contents of five areas were determined. Laboratory testing was conducted on five soil plots in the selected five suspected contaminated areas (electroplating workshop, sewage treatment area, and boiler room). Correlation analysis, infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to evaluate and analyze PTE pollution. The average contents of Cd, Co, As, Pb, Zn, and Cu at the site were higher than the background values in the Guangxi soil. The Probability Mass Function (PMF) model was used to perform a source apportionment of the PTEs and determine the main pollution sources and their contribution rates. The results of the single factor pollution of the PTEs showed that Cd, Ar, and Cr were heavy pollutants, and Co was a light pollutant. The Nemerow comprehensive pollution index analysis showed that the study area was heavily polluted. The Earth accumulation index results show that Cd exhibited a very serious accumulation, Cu and Zn exhibited mild to moderate accumulations, and As and Co exhibited moderate accumulations. The FTIR results showed that C=O in the soil was chelated with PTEs in some samples, which weakened the characteristic peaks of C=O in proteins and polypeptides. The XRD results showed that cadmium hydroxide, lead oxide, and zinc hydroxide were present in the soil samples. The XPS results showed that the production of O²⁻ in the O 1s high-resolution spectra mainly came from the metal oxides produced by the polluting metals. Meanwhile, the microbial results showed that the pollution risk of PTEs affected the soil microbial community structure and diversity to some extent.

The study of ecological security patterns is of great significance to the balance between regional economic development and environmental protection. By optimizing the regional ecological security pattern through reasonable land-use planning and resource management strategies, the purpose of maintaining ecosystem stability and improving ecosystem service capacity can be achieved, and ultimately regional ecological security can be achieved. As a typical ecological civilization city in the middle reaches of the Yangtze River, Yichang City is also facing the dual challenges of urban expansion and environmental pressure. The construction and optimization of its ecological security pattern is the key to achieving the harmonious coexistence of economic development and environmental protection and ensuring regional sustainable development. Based on the ecological environment characteristics and land-use data of Yichang City, this paper uses morphological spatial pattern analysis and landscape connectivity analysis to identify core ecological sources, constructs a comprehensive ecological resistance surface based on the sensitivity–pressure–resilience (SPR) model, and combines circuit theory and Linkage Mapper tools to extract ecological corridors, ecological pinch points, and ecological barrier points and construct the ecological security pattern of Yichang City with ecological elements of points, lines, and surfaces. Finally, the community mining method was introduced and combined with habitat quality to analyze the spatial topological structure of the ecological network in Yichang City and conduct ecological security zoning management. The following conclusions were drawn: Yichang City has a good ecological background value. A total of 64 core ecological sources were screened out with a total area of 3239.5 km². In total, 157 ecological corridors in Yichang City were identified. These corridors were divided into 104 general corridors, 42 important corridors, and 11 key corridors according to the flow centrality score. In addition, 49 key ecological pinch points and 36 ecological barrier points were identified. The combination of these points, lines, and surfaces formed the ecological security pattern of Yichang City. Based on the community mining algorithm in complex networks and the principle of Thiessen polygons, Yichang City was divided into five ecological functional zones. Among them, Community No. 2 has the highest ecological security level, high vegetation coverage, close distribution of ecological sources, a large number of corridors, and high connectivity. Community No. 5 has the largest area, but it contains most of the human activity space and construction and development zones, with low habitat quality and severely squeezed ecological space. In this regard, large-scale ecological restoration projects should be implemented, such as artificial wetland construction and ecological island establishment, to supplement ecological activity space and mobility and enhance ecosystem service functions. This study aims to construct a multi-scale ecological security pattern in Yichang City, propose a dynamic zoning management strategy based on complex network analysis, and provide a scientific basis for ecological protection and restoration in rapidly urbanizing areas.

Low-pressure N₂ adsorption experiments were conducted on 20 samples from the Doushantuo Formation in the Yichang area to quantitatively characterize their pore structures and fractal properties. The samples are mainly composed of quartz, dolomite, and clay minerals, with minor amounts of feldspar, calcite, and pyrite. The N₂ adsorption–desorption isotherms display typical type IV characteristics with a pronounced hysteresis loop, indicating that mesopores are dominant. The specific surface areas range from 3.78 to 11.49 m²/g, and the total pore volumes range from 0.0039 to 0.0169 mL/g, with mesopores contributing most of the total pore volume. Fractal analysis based on the FHH model reveals two distinct fractal dimensions (D_f): D_f1 = 2.5–2.9 for small pores and D_f2 = 2.0–2.3 for large pores. The fractal dimensions are negatively correlated with TOC, quartz, and carbonate contents but positively correlated with clay and pyrite contents. Higher organic matter content tends to produce relatively smooth organic pores, reducing pore heterogeneity, whereas higher clay content increases surface roughness and structural complexity. Overall, the heterogeneity of pore structures in the Doushantuo Formation shales is primarily controlled by mineral composition and organic matter content. These results provide new insights into the pore characteristics and storage potential of Ediacaran marine shales.

Using 48 shale samples from the lower member of the Longmaxi Formation in Well YL, in the Middle Yangtze region, we investigate the fractal characteristics of pore structures across different shale lithofacies based on total organic carbon (TOC), X-ray diffraction (XRD), and low-pressure N₂ adsorption analyses. The shale succession is dominated by three lithofacies—clayey shale, mixed shale, and felsic shale—with mesopores and micropores forming the principal pore systems. N₂ adsorption–desorption isotherms exhibit pronounced hysteresis loops, and ln(V) versus ln(ln(P₀/P)) plots show distinct two-segment behaviour, indicating dual fractal dimensions within the pore network. The fractal dimension of small pores (Df₁ = 2.75–2.87) is consistently higher than that of large pores (Df₂ = 2.01–2.39), suggesting stronger structural heterogeneity in micropore–mesopore systems. Felsic shale exhibits the highest fractal dimensions, followed by mixed shale, whereas clayey shale shows the lowest values. Fractal dimensions correlate positively with TOC, clay minerals, and pyrite content, but negatively with quartz, feldspar, and carbonate minerals. Lithofacies therefore exert a first-order control on pore fractal characteristics through their influence on mineralogical composition and organic matter abundance. These results demonstrate that fractal dimensions provide a robust quantitative metric for evaluating reservoir heterogeneity in Longmaxi Formation shales. Unlike previous studies that examined pore complexity at the bulk-rock scale, this study adopts a lithofacies-resolved dual-fractal framework to quantify multiscale pore heterogeneity and explicitly elucidate the roles of mineralogy and organic matter in controlling pore complexity.