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In recent years, the application of real scene 3D technology has become widespread in urban planning and cultural heritage protection. However, there has been relatively little attention paid to the construction of real scene 3D models for special natural landscapes such as caves. Given the global distribution of karst topography and the large number of naturally developed caves with diverse types, unique landscape styles, and significant scientific value, this paper enriches the research in this field. By combining ground-based and aerial remote sensing techniques, and based on 3D laser scanning and photogrammetry, we have successfully constructed a real scene 3D model of the internal structure of a karst cave with a precision better than 4 cm. Utilizing Unmanned Aerial Vehicle (UAV) oblique photography, we established a real scene 3D model of the external karst landform with a precision better than 2 cm. We also integrated the internal and external 3D models of the cave, developing a new, complete, and high-precision method for constructing real scene 3D models of karst cave landscapes. Furthermore, we proposed a method for texture reproduction in the dark environment inside the caves, enhancing the reproduction and visual appeal of the real interior. The establishment of high-precision real scene 3D models can not only serve as an effective tool for scientific research on caves but also, as replicas of the real world, play a crucial role in public dissemination and education, thereby enhancing public understanding of cave geological landscapes. [ABSTRACT FROM AUTHOR]

Karst caves, formed by the erosion of soluble carbonate rocks, provide unique ecosystems characterized by stable temperatures and high humidity. These conditions support diverse microbial communities, including wall microbial fouling, aquatic biofilms, and planktonic communities. This study discloses the taxonomic diversity of protists in aquatic biotopes of Shulgan-Tash Cave, a culturally significant site and popular tourist destination, by 18S rRNA gene metabarcoding. Our findings reveal the rich protist communities in the cave's aquatic biotopes, with the highest diversity observed in Blue Lake at the cave entrance. In contrast, Distant Lake in the depth of the cave was inhabited by specific communities of plankton, mats, and pool fingers, which exhibited lower richness and evenness, and were adapted to extreme conditions (cold, darkness, and limited nutrients). High-rank taxa including Opisthokonta, Stramenopiles, and Rhizaria dominated all biotopes, aligning with observations from other subterranean environments. Specific communities of biotopes inside the cave featured distinct dominant taxa: amoeboid stramenopile (Synchromophyceae) and flagellates (Choanoflagellatea and Sandona) in mats; flagellates (Choanoflagellatea, Bicoecaceae, Ancyromonadida) and amoeboid protists (Filasterea) in pool fingers; flagellates (Ochromonadales, Glissomonadida, Synchromophyceae), fungi-like protists (Peronosporomycetes), and fungi (Ustilaginomycotina) in plankton. The specificity of the communities was supported by LEfSe analysis, which revealed enriched or differentially abundant protist taxa in each type of biotope. The predominance of Choanoflagellatea in the communities of cave mats and pool fingers, as well as the predominance of Synchromophyceae in the cave mats, appears to be a unique feature of Shulgan-Tash Cave. The cold-tolerant yeast Malassezia recorded in other caves was present in both plankton and biofilm communities, suggesting its resilience to low temperatures. However, no potentially harmful fungi were detected, positioning this research as a baseline for future monitoring. Our results emphasize the need for ongoing surveillance and conservation efforts to protect the fragile ecosystems of Shulgan-Tash Cave from human-induced disturbances and microbial invasions. [ABSTRACT FROM AUTHOR]

Abstract In recent years, the application of real scene 3D technology has become widespread in urban planning and cultural heritage protection. However, there has been relatively little attention paid to the construction of real scene 3D models for special natural landscapes such as caves. Given the global distribution of karst topography and the large number of naturally developed caves with diverse types, unique landscape styles, and significant scientific value, this paper enriches the research in this field. By combining ground-based and aerial remote sensing techniques, and based on 3D laser scanning and photogrammetry, we have successfully constructed a real scene 3D model of the internal structure of a karst cave with a precision better than 4 cm. Utilizing Unmanned Aerial Vehicle (UAV) oblique photography, we established a real scene 3D model of the external karst landform with a precision better than 2 cm. We also integrated the internal and external 3D models of the cave, developing a new, complete, and high-precision method for constructing real scene 3D models of karst cave landscapes. Furthermore, we proposed a method for texture reproduction in the dark environment inside the caves, enhancing the reproduction and visual appeal of the real interior. The establishment of high-precision real scene 3D models can not only serve as an effective tool for scientific research on caves but also, as replicas of the real world, play a crucial role in public dissemination and education, thereby enhancing public understanding of cave geological landscapes.

Stenotrophomonas maltophilia (S. maltophilia) is an emerging opportunistic pathogen that exhibits resistant to a majority of commonly used antibiotics. Phages have the potential to serve as an alternative treatment for S. maltophilia infections. In this study, a lytic phage, A1432, infecting S. maltophilia YCR3A-1, was isolated and characterized from a karst cave. Transmission electron microscopy revealed that phage A1432 possesses an icosahedral head and a shorter tail. Phage A1432 demonstrated a narrow host range, with an optimal multiplicity of infection of 0.1. The one-step growth curve indicated a latent time of 10  min, a lysis period of 90  min, a burst size of 43.2 plaque-forming units per cell. In vitro bacteriolytic activity test showed that phage A1432 was capable to inhibit the growth of S. maltophilia YCR3A-1 in an MOI-dependent manner after 2  h of co-culture. BLASTn analysis showed that phage A1432 genome shares the highest similarity (81.46%) with Xanthomonas phage Xoo-sp2 in the NCBI database, while the query coverage was only 37%. The phage contains double-stranded DNA with a genome length of 61,660  bp and a GC content of 61.92%. It is predicted to have 79 open reading frames and one tRNA, with no virulence or antibiotic resistance genes. Phylogenetic analysis using terminase large subunit and DNA polymerase indicated that phage A1432 clustered with members of the Bradleyvirinae subfamily but diverged into a distinct branch. Further phylogenetic comparison analysis using Average Nucleotide Identity, proteomic phylogenetic analysis, genomic network analysis confirmed that phage A1432 belongs to a novel genus within the Bradleyvirinae subfamily, Mesyanzhinovviridae family. Additionally, phylogenetic analysis of the so far isolated S. maltophilia phages revealed significant genetic diversity among these phages. The results of this research will contribute valuable information for further studies on their morphological and genetic diversity, will aid in elucidating the evolutionary mechanisms that give rise to them. [ABSTRACT FROM AUTHOR]

In order to study the influence of multiple karst cave factors on surface settlement during tunnel boring machine (referred to TBM hereinafter) tunnelling, a three-dimensional numerical model is built by taking a subway project as an example and combining it with MIDAS GTS NX finite element software. Secondly, the influence of the radius, height, angle, vertical net distance and horizontal distance of the karst cave on maximum surface settlement is studied and sorted under the two working conditions of treatment and lack of treatment using the gray correlation analysis method. Additionally, a multi-factor numerical model of the untreated karst cave is established. Finally, based on the preceding research, a multi-factor prediction model for maximum surface settlement is proposed and tested. The results reveal that when the karst cave is not treated, the radius and height of the karst cave have a significant effect on maximum surface settlement. Following cave treatment however, the influence of the cave parameters on maximum settlement of the surface is greatly reduced. The calculating model created in this study offers excellent prediction accuracy and good adaptability [ABSTRACT FROM AUTHOR]

The Yunshui Cave in Shangfang Mountain, Beijing, is a famous high-altitude karst cave in northern China. As the third scientific survey of Yunshui Cave in history, this is the first time to use the latest LiDAR technology to carry out a related detection survey. Traditional cave measurement methods are limited by natural conditions and make it difficult to reach the destination. Traditional methods mainly rely on experience and obtain data with strong subjectivity, making it difficult to conduct quantitative research and obtain reproducible results in the current information era. Applying LiDAR technology to cave measurement can obtain comprehensive and accurate digital measurement results within the same survey time and reveal many richer and more accurate features of Yunshui Cave. The obtained digital measurement results can be used for 3D modeling as well as provide a large amount of accurate basic data and preliminary materials for subsequent geological, environmental, and archaeological investigation and analysis, as well as cultural and tourism resource development. The rapid geological survey of Shangfang Mountain Yunshui Cave using LiDAR technology shows that LiDAR cave geological survey technology can achieve real-time collection of centimeter-level accuracy and generate billions of points of cloud data, greatly improving survey efficiency and accuracy. At the same time, digital survey results can be obtained. Through modeling and GIS technology, all on-site survey details can be easily moved back to the laboratory for real-scene reproduction, network sharing, and dissemination. This study provides a foundation for future explorations of the Yunshui cave and highlights the potential for LiDAR techniques to enhance our understanding of complex geological structures such as caves. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pseudomonas syringae is a gram-negative plant pathogen that infects plants such as tomato and poses a threat to global crop production. In this study, a novel lytic phage infecting P. syringae pv. tomato DC3000, named phage D6, was isolated and characterized from sediments in a karst cave. The latent period of phage D6 was found to be 60 min, with a burst size of 16 plaque-forming units per cell. Phage D6 was stable at temperatures between 4 and 40 °C but lost infectivity when heated to 70 °C. Its infectivity was unaffected at pH 6–10 but became inactivated at pH ≤ 5 or ≥ 12. The genome of phage D6 is a linear double-stranded DNA of 307,402 bp with a G + C content of 48.43%. There is a codon preference between phage D6 and its host, and the translation of phage D6 gene may not be entirely dependent on the tRNA library provided by the host. A total of 410 open reading frames (ORFs) and 14 tRNAs were predicted in its genome, with 92 ORFs encoding proteins with predicted functions. Phage D6 showed low genomic similarity to known phage genomes in the GenBank and Viral sequence databases. Genomic and phylogenetic analyses revealed that phage D6 is a novel phage. The tomato plants were first injected with phage D6, and subsequently with Pst DC3000, using the foliar spraying and root drenching inoculum approach. Results obtained after 14 days indicated that phage D6 inoculation decreased P. syringae-induced symptoms in tomato leaves and inhibited the pathogen's growth in the leaves. The amount of Pst DC3000 was reduced by 150- and 263-fold, respectively. In conclusion, the lytic phage D6 identified in this study belongs to a novel phage within the Caudoviricetes class and has potential for use in biological control of plant diseases. [ABSTRACT FROM AUTHOR]

Abstract Background Karst caves serve as natural laboratories, providing organisms with extreme and constant conditions that promote isolation, resulting in a genetic relationship and living environment that is significantly different from those outside the cave. However, research on cave creatures, especially Opiliones, remains scarce, with most studies focused on water, soil, and cave sediments. Results The structure of symbiotic bacteria in different caves were compared, revealing significant differences. Based on the alpha and beta diversity, symbiotic bacteria abundance and diversity in the cave were similar, but the structure of symbiotic bacteria differed inside and outside the cave. Microorganisms in the cave play an important role in material cycling and energy flow, particularly in the nitrogen cycle. Although microbial diversity varies inside and outside the cave, Opiliones in Beijing caves and Hainan Island exhibited a strong similarity, indicating that the two environments share commonalities. Conclusions The karst cave environment possesses high microbial diversity and there are noticeable differences among different caves. Different habitats lead to significant differences in the symbiotic bacteria in Opiliones inside and outside the cave, and cave microorganisms have made efforts to adapt to extreme environments. The similarity in symbiotic bacteria community structure suggests a potential similarity in host environments, providing an explanation for the appearance of Sinonychia martensi in caves in the north.

Subsurface karst caves provide unique opportunities to study the deep biosphere, shedding light on microbial contribution to elemental cycling. Although ammonia oxidation driven by both ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) is well explored in soil and marine environments, our understanding in the subsurface biosphere still remained limited to date. To address this gap, weathered rock and sediment samples were collected from the Xincuntun Cave in Guilin City, an alkaline karst cave, and subjected to high-throughput sequencing and quantification of bacterial and archaeal amoA, along with determination of the potential nitrification rates (PNR). Results revealed that AOA dominated in ammonia oxidation, contributing 48-100% to the PNR, and AOA amoA gene copies outnumbered AOB by 2 to 6 orders. Nitrososphaera dominated in AOA communities, while Nitrosopira dominated AOB communities. AOA demonstrated significantly larger niche breadth than AOB. The development of AOA communities was influenced by deterministic processes (50.71%), while AOB communities were predominantly influenced by stochastic processes. TOC, NH4 +, and Cl- played crucial roles in shaping the compositions of ammonia oxidizers at the OTU level. Crossdomain co-occurrence networks highlighted the dominance of AOA nodes in the networks and positive associations between AOA and AOB, especially in the inner zone, suggesting collaborative effort to thrive in extreme environments. Their high gene copies, dominance in the interaction with ammonia oxidizing bacteria, expansive niche breadth and substantial contribution to PNR collectively confirmed that AOA better adapted to alkaline, oligotrophic karst caves environments, and thus play a fundamental role in nitrogen cycling in subsurface biosphere. [ABSTRACT FROM AUTHOR]

The studies of bacterial communities from extreme econiches are presently aimed mainly at analyzing the biodiversity of microorganisms using molecular biology methods. Cultivated bacteria from karst caves represent a unique group of microorganisms, the biochemical potential of which has been poorly studied. In the present work, bacteria from biofilms on the walls of the Kapova Cave (Shulgan-Tash Nature Reserve, Bashkortostan) were isolated and characterized in order to assess the ability of identified isolates to produce extracellular hydrolytic enzymes. Most of the isolates (89%) were members of the phylum Proteobacteria, with the remaining ones belonging to the phyla Actinobacteria, Firmicutes, and Bacteroidetes, which accounted for 5, 4, and 2% of the isolates, respectively. Strains with high levels of secreted protease, RNase, and amylase activity were identified as Stenotropomonas rhizophila, Lysinibacillus fusiformis, and Pseudomonas stutzeri, respectively. [ABSTRACT FROM AUTHOR]

The karst cave serves as the primary storage space in carbonate reservoirs. Simultaneously connecting multiple karst caves through hydraulic fracturing is key to the efficient development of carbonate reservoirs. However, there is lack of systematic research on the mechanisms and influencing factors of fracture propagation in carbonate rocks. This paper established models including karst cave models, single natural fracture-cave models, and multiple natural fracture-cave models based on the discrete lattice method. It thoroughly studied how geological and operational factors affect the fracture propagation and the connectivity of karst caves. The final step involved establishing a prototype well model and optimizing operation parameters. The research indicates that an increase in the Young's modulus and pore pressure of karst cave could facilitate hydraulic fracture connecting with caves. When the pore pressure is lower than that in the matrix, it will generate a repulsive effect on hydraulic fractures. The natural fracture along the hydraulic fracture path significantly facilitates the connection with caves. When the wellbore azimuth is less than 60°C, the fracture's diversion radius is small, and hydraulic fractures primarily connect with karst cave through natural fractures. When the wellbore azimuth exceeds 60°C, the fracture's diversion radius increases. Under the combined action of hydraulic fractures and natural fractures, the stimulated volume of the karst cave noticeably increases. Under the same liquid volume, increasing the injection rate could enhance the cave stimulated volume. Combining the findings from numerical simulation studies resulted in the development of a diagram that depicts the connectivity of karst caves, providing valuable insight for hydraulic fracturing operations in carbonate reservoirs. [ABSTRACT FROM AUTHOR]

Copyright of Carsologica Sinica is the property of Institute of Karst Geology, CAGS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to quantitatively assess the risk of deeply buried tunnel construction in the case of a hidden karst cave at the bottom of the tunnel, the first deeply buried tunnel construction failure model (PH−1) is firstly proposed based on the upper bound theorem of limit analysis and Protodyakonov's theory. Thereafter, based on the upper bound theorem of limit analysis and the energy dissipation theory, the second deeply buried tunnel construction failure model (PH−2) is proposed. Furthermore, on the basis of the reliability theory, the dimensionless performance functions of each damage region under these two deeply buried tunnel construction damage modes are constructed. Finally, the instability probability of each damage region under the two damage modes is calculated using the Monte Carlo sampling method. This study suggests that the PH−1 failure model is not suitable for analysing the probability of instability in tunnel construction in hard plastic red clay strata, while the PH−2 failure model is appropriate for analysing the probability of instability in tunnel construction in hard plastic red clay strata. The worse the geological conditions, the larger the diameter of the cavern, the smaller the clearance between the cavern and the tunnel, and the greater the threat to safe tunnel construction. [ABSTRACT FROM AUTHOR]

Karst caves, formed by the erosion of soluble carbonate rocks, provide unique ecosystems characterized by stable temperatures and high humidity. These conditions support diverse microbial communities, including wall microbial fouling, aquatic biofilms, and planktonic communities. This study discloses the taxonomic diversity of protists in aquatic biotopes of Shulgan-Tash Cave, a culturally significant site and popular tourist destination, by 18S rRNA gene metabarcoding. Our findings reveal the rich protist communities in the cave’s aquatic biotopes, with the highest diversity observed in Blue Lake at the cave entrance. In contrast, Distant Lake in the depth of the cave was inhabited by specific communities of plankton, mats, and pool fingers, which exhibited lower richness and evenness, and were adapted to extreme conditions (cold, darkness, and limited nutrients). High-rank taxa including Opisthokonta, Stramenopiles, and Rhizaria dominated all biotopes, aligning with observations from other subterranean environments. Specific communities of biotopes inside the cave featured distinct dominant taxa: amoeboid stramenopile (Synchromophyceae) and flagellates (Choanoflagellatea and Sandona) in mats; flagellates (Choanoflagellatea, Bicoecaceae, Ancyromonadida) and amoeboid protists (Filasterea) in pool fingers; flagellates (Ochromonadales, Glissomonadida, Synchromophyceae), fungi-like protists (Peronosporomycetes), and fungi (Ustilaginomycotina) in plankton. The specificity of the communities was supported by LEfSe analysis, which revealed enriched or differentially abundant protist taxa in each type of biotope. The predominance of Choanoflagellatea in the communities of cave mats and pool fingers, as well as the predominance of Synchromophyceae in the cave mats, appears to be a unique feature of Shulgan-Tash Cave. The cold-tolerant yeast Malassezia recorded in other caves was present in both plankton and biofilm communities, suggesting its resilience to low temperatures. However, no potentially harmful fungi were detected, positioning this research as a baseline for future monitoring. Our results emphasize the need for ongoing surveillance and conservation efforts to protect the fragile ecosystems of Shulgan-Tash Cave from human-induced disturbances and microbial invasions.

This paper investigates the dynamic responses of bottom karst caves on the shield tunnels under oblique SV waves according to the project of Dalian Metro Line 5. The viscous-spring artificial boundaries are employed and validated to assure the accuracy of seismic input. The characteristics of deformation and stress, damage evolution process and damage state of the tunnel are discussed, such as under different filling conditions of karst caves, incident angles of SV waves, the elastic modulus of grouting materials, and the combination of multiple karst caves. According to the relationship between tensile damage value and crack width, the damage state classification is divided. The results show that the tunnel's displacement and stress increase and the damage state is from no damage to severe damage with the increasing incident angle. When the incident angle is 30°, the tunnel's displacement and stress reach to the maximum, and the axial cracks width higher than 0.2 mm appear on the outer surface of the vault and bottom. The filling conditions of the bottom karst caves can influence the tunnel's circumferential damage. The structural dynamic response does not change significantly when the elastic modulus of the grouting material is greater than 10 GPa. Compared with one single cave, the damage severity of the inner surface under the multiple karst caves with a large clear distance is weakened and tends to be averaged. [ABSTRACT FROM AUTHOR]

The distribution of renewable energy sources is geographically limited. In the process of long-distance transmission, the direct current flowing from a ground electrode into the ground will cause a higher step voltage, which will bring serious security risks to the surrounding industry and life. Accurate calculation of the complex soil electrical model around the grounding electrode is crucial for site selection. Existing simulation software like CDEGS results in significant errors, particularly in complex karst topography. Therefore, constructing a finite element model that accurately reflects the characteristics of geotechnical soil near the DC grounding electrode is an essential but unresolved problem. This paper establishes a soil electrical model for karst topography and explores the impact of cave-type caverns and underground rivers on the step voltage distribution of DC grounding electrodes. These research findings can guide the site selection of DC transmission projects in karst topography. [ABSTRACT FROM AUTHOR]

In view of current situation of insufficient research on the theme of environmental carrying capacity of karst caves, Sanjiao Cave in Jiuxiang, Yiliang, Yunnan is taken as an example to obtain karst cave point cloud data through terrestrial laser scanning and establishes a fine three-dimensional model. According to the requirements of tourism cave planning and designing, the initial model is cut and extracted by using the height of safe water level in study area, and the lower model of safe water level is removed to obtain the tourism cave space model and accurately calculate the size of tourists' sightseeing space. On this basis, considering various cave environmental influencing factors such as CO2 concentration, heat, light and river, the traditional ecological environment capacity method is improved, and the mathematical model of karst cave environmental carrying capacity based on three-dimensional model is established to calculate the maximum environmental carrying capacity of undeveloped caves, so as to better guide the development and design of karst caves. Compared with the traditional calculation method, it is found that heat is the most limiting factor of environmental carrying capacity of cave tourism. At the same time, according to the calculation results, the maximum difference in instantaneous bearing capacity is 19 146 people, and the maximum difference in daily bearing capacity is 123 189 people. The calculation results are more scientific and reasonable, more in line with the actual situation. [ABSTRACT FROM AUTHOR]

This paper addresses the challenge of accurately describing the boundary of deep cavern-type reservoirs. A method is developed to extract diffraction information from the cavern and its boundaries from full wavefield seismic data using PCA wavefield separation technology. The paper describes a method for extracting diffraction information based on post-stack seismic data, and demonstrates the validity of this method in identifying cavern's boundaries via forward modeling. Subsequently, the method is applied to actual seismic data to extract diffraction information from deep caverns. By separating wavefield information at different scales, the extracted diffraction information can effectively identify the characteristics of cavernous reservoirs and their boundaries. It is verified by examples that the diffraction wave information separation method can provide a more accurate description of the distribution of deep cavern-type reservoirs, which can provide a basis for predicting this type of reservoir. [ABSTRACT FROM AUTHOR]

Karst caves are unique oligotrophic ecosystems characterised by the scarcity of organic litter, darkness, low to moderate temperatures, and high humidity, supporting diverse fungal communities. Despite their importance, little is known about the fungi in karst caves in Thailand. In 2019, we explored the culturable mycobiota associated with three selected types of substrates (air, soil/sediment and organic litter samples) from two karst caves, the Le Stegodon and Phu Pha Phet Caves, in the Satun UNESCO Global Geopark in southern Thailand. Based on morphological characters and multilocus phylogenetic analyses, eight new species (Actinomortierella caverna, Hypoxylon phuphaphetense, Leptobacillium latisporum, Malbranchea phuphaphetensis, Scedosporium satunense, Sesquicillium cavernum, Thelonectria satunensis and Umbelopsis satunensis) were described, illustrated, and compared to closely related species. These new fungal taxa form independent lineages distinct from other previously described species and classified into eight different families across six orders and two phyla (Ascomycota and Mucoromycota). This paper provides additional evidence that the karst caves located within the Satun UNESCO Global Geopark, situated in the southern region of Thailand, harbour a diverse range of newly discovered species. [ABSTRACT FROM AUTHOR]

Objective: Recent studies have revealed the biodiversity of both cultivated and uncultivated microbiomes in extreme environments. It has been shown that terrestrial subsurface ecosystems contain vast metabolic potential. Heterotrophic bacteria living in karst caves with an organic substrate deficit represent a special reserve for the isolation of metabolite producers. Here, we cultivated a bacterial community collected from biofilms in Kapova Cave (Shulgan-Tash Nature Reserve, Bashkortostan), and assessed its ability to synthesize secreted hydrolytic enzymes including RNases, proteases, and amylases. Materials and Methods: Isolated bacteria were identified by V3-V4 16S rRNA region sequencing. Enzymatic activities were assessed by measuring transparency zones around colonies grown on the appropriate substrate (RNA, casein, starch). Functional profiles of the communitieswere predicted using the Global Mapper module on iVikodak. Taxonomic, structural, and compositional diversity were calculated using Shannon-Wiener and Bray-Curtis indices. Results: Eighty-nine percent of 102 bacterial isolates were Proteobacteria, whereas other isolates were divided into three other phyla, Actinobacteria, Firmicutes, and Bacteroidetes that comprised 5%, 4%, and 2% of the isolates, respectively. Genus Pseudomonas was predominant with 42 isolates. Six isolates showed no extracellular enzymatic activity at all, 73 isolates expressed protease, 57 isolates expressed amylase, and 71 isolates had RNase activity. All three extracellular enzymes were expressed by 39 isolates. Conclusion: The biodiversity of cultivated microbiota from Kapova Cave was characterized. Bacteria that produce large amounts of protease, RNase and amylase were identified as Stenotrophomonas rhizophila, Lysinibacillus fusiformis, and Pseudomonas stutzeri, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Background Cave biotopes are characterized by stable low temperatures, high humidity, and scarcity of organic substrates. Despite the harsh oligotrophic conditions, they are often inhabited by rich microbial communities. Abundant fouling with a wide range of morphology and coloration of colonies covers the walls of the Shulgan-Tash cave in the Southern Urals. This cave is also famous for the unique Paleolithic painting discovered in the middle of the last century. We aimed to investigate the diversity, distribution, and potential impact of these biofilms on the cave’s Paleolithic paintings, while exploring how environmental factors influence the microbial communities within the cave. Results The cave’s biofilm morphotypes were categorized into three types based on the ultrastructural similarities. Molecular taxonomic analysis identified two main clusters of microbial communities, with Actinobacteria dominating in most of them and a unique “CaveCurd” community with Gammaproteobacteria prevalent in the deepest cave sections. The species composition of these biofilms reflects changes in environmental conditions, such as substrate composition, temperature, humidity, ventilation, and CO2 content. Additionally, it was observed that cave biofilms contribute to biocorrosion on cave wall surfaces. Conclusions The Shulgan-Tash cave presents an intriguing example of a stable extreme ecosystem with diverse microbiota. However, the intense dissolution and deposition of carbonates caused by Actinobacteria pose a potential threat to the preservation of the cave’s ancient rock paintings.

The Yunshui Cave in Shangfang Mountain, Beijing, is a famous high-altitude karst cave in northern China. As the third scientific survey of Yunshui Cave in history, this is the first time to use the latest LiDAR technology to carry out a related detection survey. Traditional cave measurement methods are limited by natural conditions and make it difficult to reach the destination. Traditional methods mainly rely on experience and obtain data with strong subjectivity, making it difficult to conduct quantitative research and obtain reproducible results in the current information era. Applying LiDAR technology to cave measurement can obtain comprehensive and accurate digital measurement results within the same survey time and reveal many richer and more accurate features of Yunshui Cave. The obtained digital measurement results can be used for 3D modeling as well as provide a large amount of accurate basic data and preliminary materials for subsequent geological, environmental, and archaeological investigation and analysis, as well as cultural and tourism resource development. The rapid geological survey of Shangfang Mountain Yunshui Cave using LiDAR technology shows that LiDAR cave geological survey technology can achieve real-time collection of centimeter-level accuracy and generate billions of points of cloud data, greatly improving survey efficiency and accuracy. At the same time, digital survey results can be obtained. Through modeling and GIS technology, all on-site survey details can be easily moved back to the laboratory for real-scene reproduction, network sharing, and dissemination. This study provides a foundation for future explorations of the Yunshui cave and highlights the potential for LiDAR techniques to enhance our understanding of complex geological structures such as caves.

Southwest Guizhou mining area is a typical karst development mining area in China. Under the influence of mining, the height of karst roof water conducting cracks is abnormally developed. During the rainy season, atmospheric precipitation is extremely easy to enter the underground working face through ultra-high water conducting channels, causing water inrush disasters at the working face, seriously affecting the normal production of the mine. Therefore, based on the analysis of the occurrence characteristics of karst caves in Xintian Coal Mine, the development rules of karst roof water conducting fracture zones during mining were studied by means of on-site measurement, indoor simulation, and theoretical analysis. The development mechanism of ultra-high water conducting fractures was revealed. The results show that: ①The roof karst caves in the study area have obvious zonation phenomenon from top to bottom in the layers such as the surface, the Yulongshan section, and the Changxing Formation. The surface water holes develop along the gullies, and the karst caves in the upper and middle parts of the strong aquifer in the Yulongshan section develop, presenting different forms of beads. The Changxing Formation only locally hosts karst caves with smaller diameters; ② Karst caves in karst aquifers have an important impact on water conducting fractures. Without karst caves, the development height of water conducting fractures is 43.1 m, and the fracture mining ratio is 14.4. Under karst caves, the development of water conducting fractures is abnormal, with a height of 173.1 m, and a fracture mining ratio of 57.7, which communicates with the strong limestone aquifer in the Yulong Mountain section; ③ Karst roof water conducting fissures consist of two parts: mining upward fissures and karst cave instability downward fissures. Under the influence of mining, karst caves become unstable under the combined action of concentrated stress and mining additional stress, and are prone to form downward fissures, which communicate with mining upward fissures, ultimately forming a special ultra-high water conducting fissure in southwestern Guizhou mining area.

Recently described cave species of the genus Triplophysa have been discovered in southwestern China, suggesting that the diversity of the genus is severely underestimated and that there may be many undescribed species. In this work, four new species of the genus Triplophysa are described from southwestern Guizhou Province, China, namely Triplophysa cehengensis Luo, Mao, Zhao, Xiao & Zhou, sp. nov. and Triplophysa rongduensis Mao, Zhao, Yu, Xiao & Zhou, sp. nov. from Rongdu Town, Ceheng County, Guizhou, Triplophysa panzhouensis Yu, Luo, Lan, Xiao & Zhou, sp. nov. from Hongguo Town, Panzhou City, Guizhou, and Triplophysa anlongensis Song, Luo, Lan, Zhao, Xiao & Zhou, sp. nov. from Xinglong Town, Anlong County, Guizhou. These four new species can be distinguished from all recognized congeners by a combination of morphological characteristics and significant genetic divergences. The discovery of these species increases the number of known cave species within the genus Triplophysa to 39, making the genus the second most diverse group of cave fishes in China after the golden-line fish genus Sinocyclocheilus. Based on the non-monophyletic relationships of the different watershed systems in the phylogenetic tree, this study also discusses the use of cave species of the genus Triplophysa to determine the possible historical connectivity of river systems. [ABSTRACT FROM AUTHOR]

Background: Cave biotopes are characterized by stable low temperatures, high humidity, and scarcity of organic substrates. Despite the harsh oligotrophic conditions, they are often inhabited by rich microbial communities. Abundant fouling with a wide range of morphology and coloration of colonies covers the walls of the Shulgan-Tash cave in the Southern Urals. This cave is also famous for the unique Paleolithic painting discovered in the middle of the last century. We aimed to investigate the diversity, distribution, and potential impact of these biofilms on the cave's Paleolithic paintings, while exploring how environmental factors influence the microbial communities within the cave. Results: The cave's biofilm morphotypes were categorized into three types based on the ultrastructural similarities. Molecular taxonomic analysis identified two main clusters of microbial communities, with Actinobacteria dominating in most of them and a unique "CaveCurd" community with Gammaproteobacteria prevalent in the deepest cave sections. The species composition of these biofilms reflects changes in environmental conditions, such as substrate composition, temperature, humidity, ventilation, and CO2 content. Additionally, it was observed that cave biofilms contribute to biocorrosion on cave wall surfaces. Conclusions: The Shulgan-Tash cave presents an intriguing example of a stable extreme ecosystem with diverse microbiota. However, the intense dissolution and deposition of carbonates caused by Actinobacteria pose a potential threat to the preservation of the cave's ancient rock paintings. [ABSTRACT FROM AUTHOR]

Nitrate (NO3−) pollution in karst areas has been widely discussed, which affects human health and the ecological environment. To investigate nitrate sources and their perturbations on cave hydrogeochemistry in karst cave systems, this study was conducted in Mahuang Cave, a karst cave in Southwest China, to assess the impact of human activities on the karst carbon cycle and the environment. The results show that (1) the variations of the water-soluble ions in Mahuang Cave are mainly controlled by carbonate weathering, and the cave water chemistry is characterized as the HCO3–Ca–Mg and HCO3–SO4–Ca–Mg types. (2) The dual isotopes and stable isotope Bayesian mixing model (SIAR) show that chemical fertilizers (41.5%) and soil nitrogen (33.75%) are the main nitrate sources in the cave water bodies, followed by manure and sewage (17.25%) and atmospheric precipitation (7.5%). (3) The significant enrichment of dissolved inorganic carbon isotope (δ13CDIC) in Mahuang Cave reveals that nitric acid produced by nitrification accelerates carbonate weathering in Mahuang Cave, and the carbon source effect of the carbon cycle in the cave is enhanced. Consequently, the response of cave drips and sediments to external environments is disturbed. [ABSTRACT FROM AUTHOR]

As a unique ecosystem, Karst caves harbor an impressive diversity of specific fungi. However, the factors and mechanisms that shape fungal biodiversity in caves remain elusive. In this study, we explored the assembly patterns of fungal communities based on our previous research in eight representative Karst caves in Southwest China. Our results indicated that dispersal limitation plays a crucial role in shaping the overall fungal community as well as specific communities in rock, sediment, and water samples. However, "Undominated" processes contributed more than dispersal limitation in air samples. Interestingly, the dominant assembly processes varied between caves. Consistently, environmental selection had a minor impact on the assembly of fungal communities. Among the examined spatial and environmental variables, latitude, longitude, altitude, and temperature were found to significantly influence fungal communities irrespective of substrate type. These findings provide valuable insights into the ecological factors governing fungal community assembly in Karst caves. [ABSTRACT FROM AUTHOR]

Karst cave was revealed in the construction of the Laobishan Tunnel of the new Chengdu-Kunming Railway, involving the risks of falling blocks from the top of the cave and flooding by karst water pouring backwards, which needs appropriate crossing scheme. Some investigation methods were used to determine the type of karst cave, and a scheme of arch bridge with protective structure was proposed to cross the karst cave, with specific structural design. To support the engineering design of the arch bridge and the retaining bridge structure, the three-dimensional space simulation analysis model of the bridge structure was established by using the finite element method. For the construction stage and the completion stage, the static performance of the main arch ring of the arch bridge was systematically analyzed from the angles of deformation and stress, and the strength and cracks of the most unfavorable section under stress were discussed. Results show that, the water supply in the karst cave is mainly bedrock fissure water, and the karst cave is stable. At the stage of construction, the maximum compressive stress and maximum tensile stress of the main arch ring are 5.94 MPa and 2.74 MPa respectively, and the position of occurrence is at the lower and upper edge of the arch foot of the main arch ring. At the stage of completion, the midspan arch crown section and arch foot section are the most unfavorable section positions under different load combinations. The maximum normal stress of concrete and reinforcement are 11.88 MPa and 189.07 MPa respectively, and the maximum width of crack is 0.19 mm. The stress and crack meet the requirements of relevant specifications. [ABSTRACT FROM AUTHOR]

The rare plant Primula esquirolii, a karst cave species in the family Primulaceae, endemic to Guizhou, China, and with a presumed extremely small population, had not previously been observed since 1910. It is categorized as Endangered on the China Species Red List. In surveys during 2018–2022, we were unable to locate the species in its type location in Pingba county, but we discovered a previously unrecorded population of 44 mature individuals, 37 of which were long homostylous and seven of which were heterostylous. These individuals were discovered in Xiuwen county in February 2022, in an area of c. 50 m2, c. 40 km from the type location. All seven heterostylous individuals showed the short-styled morph. The almost homostylous P. esquirolii potentially faces the same high genetic load as other homostylous plants, and this may have led to its small population size and potential sensitivity to habitat destruction. Field surveys and informal interviews with local people indicated that the main threats to this species are its small population size and the loss of suitable habitat as a result of human activities. The most urgent requirement for the conservation of this species is to protect the habitat of this single known extant population and to carry out ex situ conservation. Further field surveys and research are also required to improve our understanding of the status of this species.

The karst landforms in northeastern Sichuan Basin are widely developed, but the understanding of the geological characteristics, controlling factors, and spatiotemporal evolution process of karst caves is still unclear. The research object of this study is the Panlongdong karst cave in the northeastern Sichuan Basin. An outcrop geological survey was carried out, 14C isotope dating of stalactite was performed, carbon and oxygen isotope analysis was completed, and the formation process was identified. The interior of this cave is covered with karst sediments, and its original rocks are the Permian Wujiaping and Changxing formations, with secondary dissolution that has developed. The rock types, geological structure (fault, joint), and climate are the main factors behind the formation of the Panlongdong karst cave. The sedimentation of biogenic reefs and carbonate rocks is a fundamental geological condition for the development of karst processes. The geological structures provide channels for the dissolution of atmospheric precipitation. From 43.5 ka.B.P., six continuous changes in climate have intensified the formation of karst landforms. Warm, humid, and cold dry climate conditions have repeatedly occurred, and carbonate rocks have experienced varying degrees of karstification under the influence of climate. Through the four stages of structural breakup and surface dissolution, secondary cranny dissolution, selective dissolution, and detachment of rock mass and karst sediment formation, the Panlongdong karst cave was ultimately formed. The formation process of the Panlongdong karst cave is of great significance for understanding the evolution of the paleoenvironment in the northeastern Sichuan Basin. [ABSTRACT FROM AUTHOR]

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Copyright of Carsologica Sinica is the property of Institute of Karst Geology, CAGS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Seismic and drilling data were obtained to study the paleo-karst development conditions and cave developmental characteristics of the Middle-Lower Ordovician in the incised meandering canyon area on the western slope of Tahe Oilfield, Tarim Basin. Using layer leveling, tectonic trend surface, amplitude anomaly and other methods, the paleo-hydrogeographic conditions and paleo-karst fluid system were restored, the types of karst caves in the incised meandering canyon area were divided, and the development model of karst caves under the background of incised meandering canyons was re-constructed. Results showed that: (1) Early Hercynian paleo-karst was developed in the study area. The paleo-geomorphology was generally high in the east and low in the west. The karst geomorphic units were mainly valleys, karst hills and depressions. The incised meandering of the main surface water system was the lowest karst water discharge benchmark in the study area, and the underground and surface branch water systems converged from the southern and northern platforms to the central main body. (2) The underground river caves in the incised meandering canyon area were identified as subterranean river type, swallet stream type, perforated type, phreatic type along river valley and vadose type of sink hole, which were mainly distributed 0-90 m below unconformity surface. The perforated type and phreatic type along river valley were easy to be filled by mud. (3) Incised meandering canyon, karst residual hill and fault controlled the development of ancient karst caves, forming a central confluence karst cave model in the Early Hercynian incised meandering canyon area of the Tahe karst basin.

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Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

When shield tunnel passes through karst strata, the existence and development of karst caves will inevitably affect the safety of tunnel construction. Therefore, the karst caves in the construction area must be filled, and the backfill strength of karst caves will also affect the stability of surrounding rock. In this paper, the discrete element model of karst stratum is constructed by calibrating the discrete element EDEM mesoscopic parameters. The simulation of shield tunneling process under different karst cave filling intensities is realized. The influence of the ratio of cave filling strength to surrounding rock strength on the stability of surrounding rock is studied. The results show that: (1) Critical normal stress and normal contact stiffness only affect the peak stress, while critical tangential stress and tangential contact stiffness both affect elastic modulus and peak stress. (2) When the ratio of the filling strength of the cave in front of the shield to the strength of the surrounding rock is controlled between 0.8 and 1.2, the stability of the surrounding rock is less affected by the cave. (3) By comparing with the test results, when the ratio of the strength of cave filling material to the strength of surrounding rock is 0.8, the shield machine can safely pass through the front cave without excessive formation deformation. This study provides a basis for the treatment of karst caves when shield tunneling through karst areas. [ABSTRACT FROM AUTHOR]

In order to quantitatively assess the risk of deeply buried tunnel construction in the case of a hidden karst cave at the bottom of the tunnel, the first deeply buried tunnel construction failure model (PH−1) is firstly proposed based on the upper bound theorem of limit analysis and Protodyakonov’s theory. Thereafter, based on the upper bound theorem of limit analysis and the energy dissipation theory, the second deeply buried tunnel construction failure model (PH−2) is proposed. Furthermore, on the basis of the reliability theory, the dimensionless performance functions of each damage region under these two deeply buried tunnel construction damage modes are constructed. Finally, the instability probability of each damage region under the two damage modes is calculated using the Monte Carlo sampling method. This study suggests that the PH−1 failure model is not suitable for analysing the probability of instability in tunnel construction in hard plastic red clay strata, while the PH−2 failure model is appropriate for analysing the probability of instability in tunnel construction in hard plastic red clay strata. The worse the geological conditions, the larger the diameter of the cavern, the smaller the clearance between the cavern and the tunnel, and the greater the threat to safe tunnel construction.

The distribution of renewable energy sources is geographically limited. In the process of long-distance transmission, the direct current flowing from a ground electrode into the ground will cause a higher step voltage, which will bring serious security risks to the surrounding industry and life. Accurate calculation of the complex soil electrical model around the grounding electrode is crucial for site selection. Existing simulation software like CDEGS results in significant errors, particularly in complex karst topography. Therefore, constructing a finite element model that accurately reflects the characteristics of geotechnical soil near the DC grounding electrode is an essential but unresolved problem. This paper establishes a soil electrical model for karst topography and explores the impact of cave-type caverns and underground rivers on the step voltage distribution of DC grounding electrodes. These research findings can guide the site selection of DC transmission projects in karst topography.

Three new species of Polystichum (Dryopteridaceae), P. paramartini R. H. Jiang et X. C. Zhang, P. sublanceolatum R. H. Jiang et X. C. Zhang, and P. venosum R. H. Jiang et X. C. Zhang, are described and illustrated. They are all from the limestone mountains in South and Southwest China. The first two species are found in limestone caves while the third one occurs on limestone mountain slopes. Detailed descriptions, line drawings, ecological preferences, conservation status are provided.

Karst caves are usually considered as natural laboratories to study pristine microbiomes in subsurface biosphere. However, effects of the increasingly detected nitrate in underground karst ecosystem due to the acid rain impact on microbiota and their functions in subsurface karst caves have remained largely unknown. In this study, samples of weathered rocks and sediments were collected from the Chang Cave, Hubei province and subjected to high-throughput sequencing of 16S rRNA genes. The results showed that nitrate significantly impacted bacterial compositions, interactions, and functions in different habitats. Bacterial communities clustered according to their habitats with distinguished indicator groups identified for each individual habitat. Nitrate shaped the overall bacterial communities across two habitats with a contribution of 27.2%, whereas the pH and TOC, respectively, structured bacterial communities in weathered rocks and sediments. Alpha and beta diversities of bacterial communities increased with nitrate concentration in both habitats, with nitrate directly affecting alpha diversity in sediments, but indirectly on weathered rocks by lowering pH. Nitrate impacted more on bacterial communities in weathered rocks at the genus level than in sediments because more genera significantly correlated with nitrate concentration in weathered rocks. Diverse keystone taxa involved in nitrogen cycling were identified in the co-occurrence networks such as nitrate reducers, ammonium)oxidizers, and N2-fixers. Tax4Fun2 analysis further confirmed the dominance of genes involved in nitrogen cycling. Genes of methane metabolism and carbon fixation were also dominant. The dominance of dissimilatory and assimilatory nitrate reduction in nitrogen cycling substantiated nitrate impact on bacterial functions. Our results for the first time revealed the impact of nitrate on subsurface karst ecosystem in terms of bacterial compositions, interactions, and functions, providing an important reference for further deciphering the disturbance of human activities on the subsurface biosphere. [ABSTRACT FROM AUTHOR]

There is limited knowledge about microbial communities and their ecological functions in karst caves with high CO2 concentrations. Here, we studied the microbial community compositions and functions in Shuiming Cave ("SMC", CO2 concentration 3 303 ppm) and Xueyu Cave ("XYC", CO2 concentration 8 753 ppm) using Illumina MiSeq high-throughput sequencing in combination with BIOLOG test. The results showed that Proteobacteria, Actinobacteria and Bacteroidetes were dominant phyla in these two caves, and Thaumarchaeota was the most abundant in the rock wall samples of SMC. The microbial diversity in the water samples decreased with increasing HCO3− concentration, and it was higher in XYC than that in SMC. The microbial community structures in the sediment and rock wall samples were quite different between the two caves. High concentrations of CO2 can reduce the microbial diversity on the rock walls in karst caves, probably through changing microbial preference for different types of carbon sources and decreasing the microbial utilization rate of carbon sources. These results expanded our understanding of microbial community and its response to environments in karst caves with high CO2. [ABSTRACT FROM AUTHOR]

There is limited knowledge about microbial communities and their ecological functions in karst caves with high CO2 concentrations. Here, we studied the microbial community compositions and functions in Shuiming Cave ("SMC", CO2 concentration 3 303 ppm) and Xueyu Cave ("XYC", CO2 concentration 8 753 ppm) using Illumina MiSeq high-throughput sequencing in combination with BIOLOG test. The results showed that Proteobacteria, Actinobacteria and Bacteroidetes were dominant phyla in these two caves, and Thaumarchaeota was the most abundant in the rock wall samples of SMC. The microbial diversity in the water samples decreased with increasing HCO3− concentration, and it was higher in XYC than that in SMC. The microbial community structures in the sediment and rock wall samples were quite different between the two caves. High concentrations of CO2 can reduce the microbial diversity on the rock walls in karst caves, probably through changing microbial preference for different types of carbon sources and decreasing the microbial utilization rate of carbon sources. These results expanded our understanding of microbial community and its response to environments in karst caves with high CO2. [ABSTRACT FROM AUTHOR]

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