The hydrogeological conditions of the Qianbei coalfield are complex, and karst water in the roof rock frequently disrupts mining operations, leading to frequent water inrush incidents. Taking the representative Longfeng Coal Mine as a case study, research was conducted on the development pattern of the water-conducting fracture zone and the water inrush mechanisms beneath karst aquifers. On the basis of key stratum theory and calculations of the stratum stretching rate, the karst aquifer in the Changxing Formation was identified as the primary key stratum. It was deduced that the water-conducting fracture zone would develop into the karst aquifer, indicating a risk of roof water inrush at the working face. Numerical simulations were used to study the stress field, displacement field, and plastic zone distribution patterns in the overlying roof strata. Combined with similar simulation tests and digital speckle experiments, the spatiotemporal evolution characteristics of the water-conducting fracture zone were investigated. During the coal mining process, the water-conducting fracture zone will exhibit a "step-type" development characteristic, with the fracture morphology evolving from vertical to horizontal. Near the goaf boundary, the strain gradually decreases, and the instability of the primary key stratum significantly impacts the mining space below, leading to the closure of interlayer voids or the redistribution of water-conducting fissure patterns. Field measurements of the water-conducting fracture zone reveal that postmining roof fractures can be classified into tensile-shear, throughgoing, and discrete types, with decreasing water-conducting capacity in that order, the measured development height of the water-conducting fracture zone (51 m) aligns closely with the theoretical height (51.37 m) and the numerical simulation height (49.17 m). Finally, from the perspective of key stratum instability, the disaster mechanisms of dynamic water inrush and hydrostatic pressure water inrush beneath the karst aquifers in the northern Guizhou coalfield were revealed. The findings provide valuable insights for water prevention and control efforts in the Qianbei coalfield mining area.

The Nibao gold deposit, which includes both fault-controlled and strata-bound gold orebodies, constitutes an important part of the Yunnan–Guizhou–Guangxi “Golden Triangle” region. Defining the mineralization age of these gold orebodies may provide additional evidence for constraining the formation ages of low-temperature orebodies and their metallogenic distribution in South China. Petrographic studies of gold-bearing pyrites and ore-related quartz veins indicate that these pyrites coexist with quartz or filled in vein-like quartz, which suggests a possible genetic relationship between the two from Nibao gold deposit. Minerals chemistry shows that Rb and Sr are usually hosted in fluid inclusions in quartz ranging from 0.0786 to 2.0760 ppm and 0.1703 to 2.1820 ppm, respectively. The Rb–Sr isotopic composition of gold-bearing quartz-hosted fluid inclusions from the Nibao gold deposit were found to have Rb–Sr isochron ages of 142 ± 3 and 141 ± 2 Ma for both fault-controlled and strata-bound orebodies, respectively, adding more evidence to previous studies and thus revealing a regional gold mineralization age of 148–134 Ma. These results also confirm the Middle-Late Yanshanian mineralizing events of Carlin-type gold deposits in Yunnan, Guizhou, and Guangxi Provinces of Southwest China. In addition, previous studies indicated that antimony deposits in the region which were formed at ca. 148–126 Ma have a close affinity with gold deposits. This illustrates that the regional low-temperature hydrothermal gold mineralization is related in space and time to the Yanshanian (ca. 146–115 Ma) magmatic activity. Specifically, the large-scale gold and antimony mineralization are considered to be inherently related to mantle-derived mafic and ultramafic magmatic rocks associated with an extensional tectonic environment. Based on the initial ⁸⁷Sr/⁸⁶Sr ratios of 0.70844 ± 0.00022 (2σ) and 0.70862 ± 0.00020 (2σ) for gold-bearing quartz veins from fault-controlled and strata-bound gold orebodies, respectively, at the Nibao gold deposit, as well as the C, H, O, and S isotopic characteristics of gold deposits located in the Golden Triangle region, we suggest that the mantle-derived material can be involved in the formation of the Nibao gold deposit and that the ore-forming fluid can be derived from a mixed crust–mantle source.

The factors leading to mine water inrush accidents are mainly sources of water, water channels, and intensity of water inrush. Mine water rush depends mostly on whether damage leads to the overlying strata of the working face penetrating the overlying aquifer. There is therefore a need to characterize how the overlying strata of the coal seam roof fails and the development height of the water-conducting fracture zone during a roof water inrush incident. This study focuses on the Longfeng Coal Mine, northern Guizhou coalfield. Samples of rock from the roof coal seam were obtained by drilling and coring and examined under a scanning electron microscope. The results showed an undeveloped state of primary cracks in the overlying strata of the coal seam roof, with the water channel occurring mainly along mining-induced cracks. Four key strata were identified, and their fracture steps were calculated through integrating the results of the physical test of the overlying rock of the coal seam. The key strata break when the advancing distance of the working face exceeds their fracture steps. At this point, water-conducting cracks develop upwards. Simulation by FLAC3D allowed the analysis of vertical displacement, vertical stress, and evolution of the plastic zone of the roof overburden rock under different working face advancing distances. The results show that the changes in vertical stress and displacement in overburden rock initially increased rapidly, with this rate of increase subsequently slowing. The shape and maximum height of the plastic failure zone was typical trapezoid and 46.12 m, respectively. Finally, the height of the water-conducting fracture zone determined on site was 42–51.8 m. The good agreement between numerical simulation and measurements confirms that the results of this study can guide practical engineering.

The Liaohe River Estuary Wetland, located in Panjin City, plays a critical role in reducing pollution loads, maintaining biodiversity, and ensuring ecological security in China’s coastal regions, contributing significantly to the implementation of the land–sea coordination strategy. As key components of ecological restoration projects, monitoring and evaluating restoration effectiveness provide a reliable basis for decision-making and ecosystem management. This study established an innovative three-dimensional integrated monitoring and evaluation system combining satellite imagery, UAV aerial photography, and field sampling surveys, addressing the technical gaps in multi-scale and multi-dimensional dynamic ecological monitoring. Through systematic monitoring and the assessment of key indicators, including water environment, soil environment, biodiversity, water conservation capacity, and carbon sequestration capacity, we comprehensively evaluated the enhancement effects of ecological restoration projects on regional ecosystem structure, quality, and service functions. The findings demonstrated that the satellite–airborne–ground integrated monitoring technology significantly improved water quality and soil properties, enhanced soil–water conservation capabilities, and increased biodiversity indices and carbon sequestration potential. These results validate the scientific validity of ecological protection measures and the comprehensive benefits of restoration outcomes. The primary contributions of this research lie in the following: developing a novel monitoring framework that provides critical data support for decision-making, project acceptance, effectiveness evaluation, and adaptive management in ecological restoration; establishing transferable methodologies applicable not only to the Liaohe River Estuary wetlands, but also to similar ecosystems globally, showcasing broad applicability in ecological governance.

The presence of random joints, cracks, and other defects significantly affects the meso-damage mechanism and macro-mechanical behavior of the rock. This study employed micro-CT scanning, digital image processing (DIP), and the rock failure process analysis system (RFPA3D) to reconstruct a genuine mesostructure, creating a three-dimensional (3D) numerical model of jointed sandstone. Under uniaxial stress, this model facilitated the meso-damage evolution process of prefabricated cracks in sandstone with varying dip angles. Additionally, the influence of jointed sandstone heterogeneity and prefabricated cracks with various dip angles on its failure mode and meso-damage mechanical properties were investigated. Utilizing the MATLAB platform, a 3D box dimension algorithm was developed to analyze the fractal characteristics of the mesodamage evolution in the sample. This algorithm enabled the quantitative characterization of the meso-damage evolution of sandstone. This study categorized three types of sandstone final failure modes: composite shear failure, shear failure along the joint surface, and tensile failure. Additionally, linear variations in the elastic modulus and compressive strength of the jointed sandstone were observed with increasing prefabricated fracture inclination, highlighting significant anisotropy. The presence of joints was found to induce and control the failure mode of sandstone. The meso-damage evolution process of sandstone was described in terms of the fractal dimension, indicating that more severe damage corresponded to a larger fractal dimension. This approach offers a novel statistical method for studying the progression of rock damage.