Search Results (1,421)

Cave microbiota comprise metabolically diverse organisms, including microalgae, among which Bacillariophyta (diatoms) represent one of the most prominent groups, inhabiting a wide range of substrates within cave ecosystems. In contrast to aerophytic cave habitats, aquatic cave environments remain poorly studied. Therefore, the main aims of this study were to determine the diversity, spatial distribution, and seasonal dynamics of diatom assemblages in the Ponorac Stream flowing through Ravništarka Cave, and to assess the influence of environmental variables on diatom diversity and distribution. Samples were collected from six sites along the Ponorac stream in May and November 2023. Physical and chemical water parameters showed only minor variation among sampling sites. In total, 148 diatom taxa belonging to 54 genera were recorded, including several rare diatom taxa. Diatom assemblages in the Ponorac stream were characterized by high taxonomic richness, high α-diversity, and pronounced community heterogeneity. Many taxa occurred in both seasons and across multiple sites, whereas several were restricted to a single season or exhibited clear site specificity. Most diatom index values indicated generally high ecological status. This study highlights the importance of aquatic cave habitats as reservoirs of diatom diversity and their value in studying temporal and spatial variation of their communities. Full article

As a primary associated by-product of coal mining, the comprehensive utilization of coal gangue has become a core pathway for the green transformation of the energy system and the establishment of a resource recycling system. The fully mechanized top-coal caving mining method used in China lacks a quality linkage mechanism between underground matched mining and surface coal blending, resulting in significant fluctuations in coal quality, larger volumes of gangue brought to the surface, and low utilization rates of coal washing by-products. In this paper, we propose a reverse decision-making method for whole-lifecycle coal quality control and construct an ash content tracing and regulation model to coordinate coal blending and matched mining in fully mechanized caving faces. In the coal blending stage, under the constraints of calorific value balance and cost minimization, the method transforms low-calorific-value by-products, such as middlings and fine gangue, into valuable resources. In the matched mining stage, a reverse tracking model based on the surface–underground ash content balance is proposed, grounded in material flow analysis theory. The model formulates correlation equations among face length, the low calorific value of raw coal, daily advance per cycle, and caved gangue volume. It further proposes a reverse coal quality tracing theory that links commercial coal sales targets with caving process parameters. The study clarifies the deep coordination mechanism between underground matched mining and surface coal blending. The results demonstrate that the proposed method systematically establishes a closed-loop pathway integrating underground gangue reduction at the source and surface fine gangue blending. The implementation has yielded direct economic benefits totaling RMB 65.31 million, increased commercial blended coal output by 104.5 thousand tons, and reduced gangue emissions by 258.5 thousand tons. This study provides a reference for the reduction, resource utilization, and recycling of coal gangue. Full article

Karst ecosystems play an important hydrological role in regulating regional water availability and supporting biodiversity, yet they face increasing threats from deforestation, land-use conversion, and limited scientific data to inform sustainable conservation efforts. This study aims to assess karst geodiversity, aquatic habitat diversity, and freshwater endemism in the Maybrat Karst, and to explain the linkages among these three aspects as a scientific basis for regional karst conservation. The research employed geospatial analysis and descriptive ecological analysis. Data were collected through satellite image interpretation, participatory mapping, field observations, and a comprehensive literature review. Results show that the Maybrat Karst has very high geodiversity, with ±2322.91 km² (41.49%) of the region classified as karst. All seven karst elements were identified, including 40–56 hills/km², 110 water-filled dolines, 334 springs, 178 subterranean rivers, 90 caves, and three major karst lakes. Aquatic habitat diversity is likewise very high, comprising seven habitat types across the full 100–500 m elevational range, accompanied by 17 Cherax morphotypes, indicating strong environmental differentiation. The literature review identified 18 endemic freshwater species, consisting of five Cherax species, ten rainbowfish species of the genus Melanotaenia, and three additional taxa: Pseudomugil reticulatus, Glossogobius hoesei, and Zenarchopterus ornithocephala. These findings confirm that high karst geodiversity and habitat heterogeneity make the Maybrat Karst a key aquatic endemism center, highlighting the urgent national and global imperative for comprehensive karst protection to safeguard long-term biodiversity and ecosystem sustainability. Full article

Karst water systems are highly vulnerable to land use pressures, requiring integrated assessments to support conservation and management. This study evaluated the physicochemical, microbiological, and pesticide-related water quality in the Environmental Protection Area Nascentes do Rio Vermelho (APANRV), a karst conservation unit in the Brazilian Cerrado. Sixteen sampling sites (rivers, springs, and cave waters) were monitored during the dry (May 2024) and rainy (October 2024) seasons. Analyses included nutrients, major ions, Escherichia coli, and a broad spectrum of pesticides. The results showed marked spatial and seasonal variability, with elevated hardness and conductivity in karst areas due to carbonate dissolution. Nitrate and total phosphorus reached peak values of 13.59 and 0.132 mg L⁻¹, respectively, indicating localized nutrient enrichment. E. coli concentrations reached ≥2419.6 MPN 100 mL⁻¹, exceeding regulatory limits, particularly during the rainy season at recreational cave sites. Pesticides were detected in both seasons, with 11 compounds in the dry season and 8 in the rainy season, including atrazine degradation products, and maximum quantified concentrations up to 1.8 µg L⁻¹ (acephate). These findings highlight the combined influence of geology, seasonality, and land use on karst water quality and reinforce the need for continuous monitoring and targeted management strategies. Full article

With the expansion of global oil and gas resource exploration and development into deep and ultra deep layers, the efficient development of deep carbonate rock fracture cave reservoirs has become the key to ensuring energy security. However, this type of reservoir commonly faces high temperatures, high salinity, and extremely strong heterogeneity, leading to increasingly severe water content spikes caused by dominant water flow channels. Although the existing traditional inorganic plugging agent has good temperature resistance, it has the defects of great brittleness and easy cracking, while the organic polymer gel is prone to degradation failure under high temperature and high salt environments. In order to solve the above problems, a new biochar-enhanced inorganic composite gel system was constructed by using biochar prepared from agricultural and forestry waste pyrolysis as a functional enhancement component. Through rheological testing, high-temperature and high-pressure mechanical experiments, long-term thermal stability evaluation, and dynamic sealing experiments of fractured rock cores, the reinforcement and toughening laws and rheological control mechanisms of biochar on inorganic matrices were systematically studied. Research has found that a biochar content of 0.5 wt% can significantly improve the micro pore structure of the matrix. By utilizing its micro aggregate filling effect and interfacial chemical bonding, the compressive strength of the solidified body can be increased to over 2 MPa, and there is no significant decline in strength after aging at 130 °C for 30 days. More importantly, the unique “adsorption slow-release” mechanism of biochar effectively stabilizes the hydration reaction kinetics at high temperatures, extending the solidification time of the system to 15 h and solving the problem of flash condensation in deep well pumping. This system exhibits excellent shear thinning characteristics and crack sealing ability, and presents a unique “yield reconstruction” toughness sealing feature. This study elucidates the multidimensional strengthening mechanism of biochar in inorganic cementitious materials, providing technical reference for stable oil and water control in deep fractured reservoirs. Full article

Elevation is a strong proxy for the thermal environment because it causes a predictable drop in temperature and food availability. This restricts cave-dwelling bats to species with specific metabolic traits, such as torpor or migration to avoid cold stress. In this context, we aimed to reveal how thermal niche differentiation structures 25 cave-dwelling bat assemblages along elevation gradients in two of the largest Bulgarian mountains—Stara Planina and Rhodopi. Multivariate PERMANOVA showed significant differences in bat assemblages among elevation groups (F = 1.616, p = 0.046), with altitude and temperature explaining 32.4% of the variance (p = 0.001). A high degree of species turnover (91.12% dissimilarity), driven by temperature niches, was observed: mesophilic Rhinolophus species dominated warm, low-elevation caves, while cold-adapted Myotis species were more common at high elevations. SIMPER analysis identified R. euryale as an indicator in low-elevation caves (p = 0.012) and the M. myotis/blythii complex at high elevations (p = 0.003). Alpha diversity showed no variation across elevation groups (p = 0.293), indicating that species turnover occurs without overall changes to local diversity. Mid-elevation assemblages lacked specific indicator species and resembled high-elevation communities, forming an ecotone. Thermal niche partitioning, as a physiological filter, shapes cave-dwelling bat assemblages and affects climate change range-shift predictions. Full article

This research provides a new comprehensive assessment of Pikimachay Cave fossil remains of extinct fauna from the Late Pleistocene and Early Holocene, curated in the Florida Museum of Natural History’s Environmental Archaeology Program collections. The collection is the result of excavations carried out by Richard MacNeish during the 1960s and 1970s, during which he proposed pre-Clovis dates for human occupation in South America. Archival records housed across three institutions were compiled to reconstruct the spatial distribution of megafauna within the cave. Taphonomic observations of the bone assemblage were conducted to better understand depositional processes and cave conditions. Based on the spatial distribution of fossil evidence mapped and documented by layer and the taphonomic evidence of the bone assemblage, we conclude that the cave functioned primarily as a giant ground sloth burrow, also used by humans and carnivores. Future research, including additional radiocarbon dates and better contextualization of the deposits, will be essential for better understanding the fossil fauna represented in the cave and the ecological relationships among humans, carnivores and extinct species in the highlands of Perú. Full article

Portable Buddhist shrines refer to small-scale mobile or assembled shrines, typically made of wood, stone, clay, and metal. They were initially used as temporary ritual sites or ornamental attachments for temples and stupas, later becoming independent objects of devotion. This art form, the origins of which can be traced to ancient India and later diverse regional traditions, has been discovered in significant quantities along the Silk Road and neighboring regions. Previously, scholarly attention centered primarily on exquisite wall shrines, stupa-shaped shrines, and stele-shaped shrines. However, when factors such as the spatial arrangement and ritual functions of mobile ritual sites are taken into account, along with the materials and techniques employed in creating Buddhist shrines, artifacts such as badge-style bronze Buddha statues, painted silk banners, and wooden panel paintings may also be classified as portable Buddhist shrines. Accordingly, portable Buddhist shrines can be divided into three forms: pedestal, hanging, and open–close or mother–child. A key reason for this expanded classification is that all such forms are functionally and stylistically linked to large-scale cave temples. Moreover, these shrines share a common visual grammar, defined by the dynamic integration of images and texts and the mutual imitation and complementarity of statue and painting. This represents a quintessential example of cross-cultural dissemination and the coexistence of local traditions in Buddhist art. Full article

The article presents the preliminary data from the excavation of the Azurrague 1 Dolmen (Ourém), carried out within the MEDICE II project, highlighting the importance of its location in a karstic landscape marked by a strong tradition of funerary cults in natural cavities. The dolmen structure features a heptagonal chamber and a short passage, with ritual deposits that include macrolithic tools, polished axes, ceramics, and human remains dated between the beginning of the Late Neolithic and the Middle Chalcolithic. The data indicates practices of secondary burial, continuity of regional lithic traditions, and a symbolic integration between exogenous architectural forms and endogenous ritual content established in caves. The proximity to caves with contemporary chronologies, such as Lapa da Furada, reinforces the coexistence of differentiated yet interconnected ritual spaces. Analogies with the Rego da Murta Megalithic Complex, caves and other sites in the Alto Nabão region support the hypothesis of a hybrid, long-lasting cultural system in which megalithic monumentalization is associated with ancestral symbolic practices. Full article

Planform evolution and terrestrial habitat health of two representative mid-channel bars (Baishazhou bar and Tianxingzhou bar) in the urban reach of the Middle Yangtze River in Wuhan City have not been understood under the combined influences of natural forcing and human activities. Using dry-season Landsat imagery (1989–2020), hydrological records from the Hankou gauging station (1990–2019), and field surveys, we quantified bar-morphology changes and examined the mechanisms underlying their differentiated scouring. We also developed an indicator system to evaluate terrestrial habitat health on mid-channel bars. Indicator weights were determined using a combined weighting approach integrating the Analytic Hierarchy Process and the entropy weight method. Since the Three Gorges Dam began operation, the runoff in the Wuhan reach has decreased only slightly (6.72%), whereas sediment load decreased sharply (69.88%), causing net scouring of both bars. Baishazhou bar, in a straight anabranching reach, lost 43.83% of its area (1989–2020), with erosion concentrated at the head and main channel margin and caving. Tianxingzhou bar, in a mildly curved reach, had moderate shrinkage (26.33%, 1992–2022) as revetments curbed head/right margin retreat. Both bars were “very healthy” in natural attributes, with the Baishazhou bar showing longer water–land ecotone exposure (217 d) and higher vegetation cover (92%). Socially, Baishazhou bar was “sub-healthy” due to unprotected shrinkage, and Tianxingzhou bar was “unhealthy” due to area loss and low permeability of hard works. Overall, both bars were “healthy”. These findings provide a basis for ecological conservation and habitat restoration of bar wetlands. Full article

Pulmonary histoplasmosis is often misdiagnosed as or coinfected with pulmonary tuberculosis (TB). This study aims to analyze the misdiagnosis or co-occurrence of published cases of pulmonary TB and pulmonary histoplasmosis. Cases of histoplasmosis with dissemination were excluded, as it affects other organs. Systematic research was conducted using PubMed, EBSCOhost, ProQuest, BioRxiv, and MedRxiv databases. Twenty-seven articles were included, covering a total of 51 cases. Males were predominantly affected, with a median age of 54 years. Exposure to caves and farming occupations were identified as the primary sources of infection (61.9%). The most common clinical symptoms were fever (80%) and cough (82.5%). Laboratory tests revealed culture positivity in 77.1% of cases, with sputum being the most frequently used specimens. In proven pulmonary histoplasmosis, antibody tests were positive in 18 out of 24 cases. Chest X-rays commonly showed cavities, infiltrates, and nodules, with an increase in nodular pattern in recent cases. The number of pulmonary nodules detected was higher on chest computed tomography (CT). Radiologic abnormality could occur in any lung region. This review suggests the potential for misdiagnosis and/or coinfection of pulmonary histoplasmosis and pulmonary TB. The combination of clinical suspicion, radiological findings, antibody and/or antigen testing could improve the diagnosis of pulmonary histoplasmosis. Full article

No depiction of the Medicine Buddha has been identified in the Mogao Grottoes prior to the Sui Dynasty. Through a re-examination of the sculptural program and the ink inscriptions in Mogao Cave 285, this study demonstrates that the preaching scene on the south side of the east wall, whose principal figure bears the inscription “Amitāyus Buddha”, exhibits a closer textual and iconographic correspondence with the Guanding jing than with the Pure Land texts proposed in prior research. Based on textual, iconographic, and spatial evidence, this study argues that the preaching scene on the north side, corresponding to the south scene, also derives from the Guanding jing, with the principal figure identified as the “Medicine Buddha of Lapis Lazuli Crystal Radiance”. This new discovery establishes that the east wall of Mogao Cave 285 contains the earliest depiction of the Medicine Buddha at the Mogao Grottoes, dating to the Western Wei Dynasty. This study substantially revises the established chronology of the Medicine Buddha cult in the Dunhuang region and calls for a reassessment of the textual foundations underpinning the artistic program of Mogao Cave 285. Full article

To address the problems of strong roof integrity, severe energy accumulation, and difficult caving in thick and hard roofs, a three-dimensional numerical study on fracture propagation and pressure-relief control durisng segmented hydraulic fracturing was carried out based on the engineering geological conditions of the 6125-1 working face at the Haishiwan Coal Mine, Shaanxi Province, China. using the ABAQUS finite element platform coupled with Ins-coh cohesive elements. A systematic analysis was conducted to elucidate the effects of elastic modulus, Poisson’s ratio, injection rate, and fluid viscosity on fracture initiation, stress evolution, and fractured volume. The results show that for every 10 GPa increase in elastic modulus, the average fractured volume decreases by 8%, and the fracture width exhibits a marked reduction; increasing Poisson’s ratio enhances the lateral deformation compatibility of the rock mass, raising the fracture width and volumetric growth rate by approximately 3% and 5%, respectively, although an excessively high Poisson’s ratio induces stress diffusion and reduces fracture stability. When the injection rate increases from 0.01 m³/s to 0.025 m³/s, the fractured volume increases by about 160%, and the maximum fracture width increases by 43%, whereas increasing fluid viscosity exerts a limited influence on volumetric growth but is conducive to stabilizing fracture morphology. Field observations via borehole imaging and seepage confirm full fracture connectivity within the roof and the formation of a continuous rupture zone, promoting timely roof breakage and caving along the dip direction and thereby creating favorable conditions for reducing rockburst hazards at the working face. This study clarifies the mechanical mechanisms and multi-parameter coupling laws governing hydraulic fracture propagation in thick and hard roofs, providing a theoretical basis and engineering reference for roof pressure-relief control and rockburst-resistant design under similar geological conditions. Full article

Iron-ore extraction plays a central role in the global economy, but several major mining areas overlap with ecologically unique ferruginous landscapes in the Brazilian Amazon, including caves that harbor endemic and highly specialized invertebrate fauna. Reconciling mineral exploitation with biodiversity conservation requires objective ecological criteria capable of supporting evidence-based decision-making. In this study, we evaluated how cave attributes and surrounding landscape features jointly structure invertebrate communities in pristine ferruginous caves of the Amazon and assessed their relative importance and environmental thresholds. Invertebrates were sampled in 69 iron-ore caves during dry and wet seasons, and 28 environmental variables related to cave morphology, microclimate, trophic resources, lithology, vegetation cover, and external climate were measured in subterranean habitats and adjacent landscapes. Our results demonstrate a clear scale-dependent pattern: cave attributes primarily regulated species richness, troglobitic richness, taxonomic distinctness, and seasonal beta diversity, whereas landscape features exerted stronger control over species composition, including troglobitic assemblages. Threshold analyses identified specific combinations of cave and landscape attributes associated with biologically pristine communities. These findings highlight that assessments of ferruginous cave biodiversity must integrate landscape-scale metrics, be conducted in unaltered environments, and prioritize networks of caves rather than isolated sites. This integrative framework provides robust ecological support for conservation planning and the sustainable management of iron-ore cave systems in the Amazon. Full article

The red sandstone rock mass and sculptures within the Xumishan Grottoes exhibit multiple forms of weathering damage, including flaking, hollows, efflorescence, and salt efflorescence. Among these, flaking and salt efflorescence are the most pronounced, posing a severe threat to the long-term preservation of the cave’s cultural relics. This study employs SEM-EDS, XRD, XRF and IC techniques to conduct scientific analysis and characterization of the weathering products on the surface of red sandstone. By integrating the lithology of the red sandstone itself with its depositional environment, the study investigates the causes of surface weathering in red sandstone. Research findings indicate that the lithology of the cave site consists primarily of muddy siltstone, with gypsum and mirabilite present within the weathered red sandstone, alongside minor quantities of Epsom salt and chloride salts. The migration and enrichment of these soluble salts within the rock mass constitute the key chemical factors triggering efflorescence and spalling in sandstone. Concurrently, influenced by the grottoes’ environmental conditions, periodic temperature fluctuations and moisture migration further promote freeze–thaw cycles and the crystallization–dissolution cycle of salts, accelerating the weathering process of the red sandstone within the Xumishan Grottoes. Full article