Influence of CO_(2)/HCO_(3)^(-) on Microbial Communities in Two Karst Caves with High CO_(2)

There is limited knowledge about microbial communities and their ecological functions in karst caves with high CO_(2)concentrations.Here,we studied the microbial community compositions and functions in Shuiming Cave( "SMC",CO_(2)concentration 3 303 ppm) and Xueyu Cave( "XYC",CO_(2)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 HCO_(3)^(-)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 CO_(2)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 CO_(2).

Culturable mycobiota from Karst caves in China II,with descriptions of 33 new species

Karst caves are characterized by darkness,low temperature,high humidity,and oligotrophic organisms due to its relatively closed and strongly zonal environments.Up to now,1626 species in 644 genera of fungi have been reported from caves and mines worldwide.In this study,we investigated the culturable mycobiota in karst caves in southwest China.In total,251 samples from thirteen caves were collected and 2344 fungal strains were isolated using dilution plate method.Preliminary ITS analyses showed that these strains belonged to 610 species in 253 genera.Among these species,88.0%belonged to Ascomy-cota,8.0%Basidiomycota,1.9%Mortierellomycota,1.9%Mucoromycota,and 0.2%Glomeromycota.The majority of these species have been previously known from other environments,and some of them are known as mycorrhizal or pathogenic fungi.About 52.8%of these species were discovered for the first time in karst caves.Based on morphological and phyloge-netic distinctions,33 new species were identified and described in this paper.Meanwhile,one new genus of Cordycipitaceae,Gamszarea,and five new combinations are established.This work further demonstrated that Karst caves encompass a high fungal diversity,including a number of previously unknown species.Taxonomic novelties:New genus:Gamszarea Z.F.Zhang&L.Cai;Novel species:Amphichorda cavernicola,Aspergillus limoniformis,Aspergillus phialiformis,Aspergillus phialosimplex,Auxarthron chinense,Auxarthron guangxiense,Auxarthronopsis globiasca,Auxarthronopsis pedicellaris,Auxarthronopsis pulverea,Auxarthronopsis stercicola,Chrysosporium pallidum,Gamszarea humicola,Gamszarea lunata,Gamszarea microspora,Gymnoascus flavus,Jattaea reniformis,Lecanicillium magnisporum,Microascus collaris,Microas-cus levis,Microascus sparsimycelialis,Microascus superficialis,Microascus trigonus,Nigrospora globosa,Paracremonium apiculatum,Paracremonium ellipsoideum,Paraphaeosphaeria hydei,Pseudoscopulariopsis asperispora,Setophaeosphaeria microspora,Simplicillium album,Simplicillium humicola,Wardomycopsis dolichi,Wardomycopsis ellipsoconidiophora,Wardomycopsis fusca;New combinations:Gamszarea indonesiaca(Kurihara&Sukarno)Z.F.Zhang&L.Cai,Gamszarea kalimantanensis(Kurihara&Sukarno)Z.F.Zhang&L.Cai,Gamszarea restricta(Hubka,Kubátová,Nonaka,Čmoková&Řehulka)Z.F.Zhang&L.Cai,Gamszarea testudinea(Hubka,Kubátová,Nonaka,Čmoková&Řehulka)Z.F.Zhang&L.Cai,Gamszarea wallacei(H.C.Evans)Z.F.Zhang&L.Cai.

Stability analysis on tunnels with karst caves using the distinct lattice spring model

The effects of karst caves on tunnel stability were numerically investigated using the distinct lattice spring model(DLSM).The DLSM was validated by investigating the mechanical behavior of Brazilian discs with various sizes of central circular holes.Then,the effects of karst cave on U-shaped tunnel were investigated under various karst caves positions(top,bottom,and right side of the tunnel),tunnelcave distances(0.5-4 times the radius of the tunnel arc),and cave shapes(circular,rectangular flat,and rectangular vertical caves).The failure processes of the tunnel under those various conditions were analyzed and both the failure process and the final failure patterns of the tunnel were discussed.Numerical simulation demonstrated that karst caves around the tunnel could weaken the stability of the tunnel,indicating tunnel-cave distance effects.The closer the cave to the tunnel,the weaker the tunnel under loading.This effect was not significant when the tunnel-cave distance(d)was larger than three times the tunnel arc radius(R).In addition,the final failure pattern of the tunnel and its surrounding rock mass were dependent on both the position and the size of the cave.The larger the cave,the weaker the tunnel and its surrounding rock mass.Furthermore,compared with those cases with top and bottom caves,the tunnel with a right side cave had more impacts on tunnel stability.The main research finding could help engineers carry out stability analysis on tunnels in karst areas and take effective measures to enhance tunnel stability.

Baiyun Cave in Naigu Shilin,Yunnan Karst,China

The Baiyun cave is a 380 m long karst cave in the Naigu Shilin, situated 70 km southeast of Kunming, Yunnan Province, China. The prevailing orientations of the cave passages are N110°–120°E and N0°-10°W and those of the fissures in the cave are N30°–40°W and N20°–30°W. The cave is developed in the thick-bedded Lower Permian Qixia Formation. The cave has an active water flow and is currently at the near water-table stage. There are large amounts of different infills of cave sediments. The cave shows different stages of paragenesis. The palaeomagnetic analysis of cave sediments shows that their ages are younger than 780 ka B.P. (the Brunhes Chron). The upper part of the sampled profile belongs to the reverse Blake event (112.3–117.9 ka B.P.). The formation of the Baiyun cave is directly connected with the development of the Naigu Shilin. The formation of karst underground and surface features depends on the regional tectonic deformation and the Cenozoic extension of the study area.

A New Species of Odorrana Inhabiting Complete Darkness in a Karst Cave in Guangxi, China

A new species of the genusOdorrana is described from a completely dark karst cave of northeastern Guangxi, southern China. The new species,Odorranalipuensissp. nov., can be distinguished from its congeners by a combination of the following characters： medium size （SVL： 40.7–47.7 mm in males, 51.1–55.4 mm in females）;tips of all but ifrst ifnger expanded with circummarginal grooves; smooth, grass-green dorsum with irregular brown mottling; pineal body invisible; throat to upper abdomen with gray mottling; dorsal surfaces of limbs with brown bands; dorsolateral fold absent; tiny spinules on lateral body, temporal region, and anterior and posterior edge of tympanum;white nuptial pad present on ifnger I; males lacking vocal sacs; females having creamy yellow eggs, without black poles. Uncorrected sequence divergences betweenO.lipuensissp. nov. and all homologous 16S rRNA sequences ofOdorrana available on GenBank is equal to or greater than 4.9%. Currently, the new species is only known from the type locality.

Characteristics and development model of karst reservoirs in the fourth member of Sinian Dengying Formation in central Sichuan Basin,SW China

The reservoir space,types and distribution characteristics of karst carbonate gas reservoirs in the fourth member of Sinian Dengying Formation(Deng 4 Member)in central Sichuan Basin are analyzed based on the drilling,logging and seismic data.A development model of karst reservoirs is constructed to support the high-efficiency development of gas pools.The research shows that the reservoirs in Deng 4 Member have mainly small-scale karst vugs and fractures as storage space,and can be divided into three types,fracture-vug,pore-vug and pore types.The development patterns of the karst reservoirs are determined.On the plane,the karst layers increase from 65 m to 170 m in thickness from the karst platform to the karst slope,and the high-quality reservoirs increase from 25.0 m to 42.2 m in thickness;vertically,the reservoirs at the top of Deng 4 Member appear in multiple layers,and show along-bedding and along fracture dissolution characteristics.The reservoirs at the bottom are characterized by the dissolution parallel to the water level during the karstification period,and have 3-5 large-scale fracture-cave systems.Based on the reservoir development characteristics and the genetic mechanism,three types of reservoir development models of karst reservoir are established,i.e.,bed-dissolved body,fracture-dissolved body and paleohorizon-dissolved body.The construction of karst reservoir development models and seismic response characteristics of the three types of reservoirs can provide parameter for well placement and trajectory design,and substantially improve productivity and development indices of individual wells and gas reservoirs.The designed production capacity of the gas reservoir has enhanced from the initial 3.6 billion to 6 billion cubic meters,making the profit of the reservoir development increase noticeably.

Karstsinnectes cehengensis(Cypriniformes:Nemacheilidae),a new species of cave fish from Guizhou,China

Four species of the genus Karstsinnectes,which live in dark,low-energy groundwater ecosystems,are currently recorded,mainly distributed in the upstream of the Pearl River,the Youjiang River and the Hongshui River.Completing biodiversity surveys is particularly difficult due to the particular cave habitats inhabited by these species.In this work,we describe a new cave fish of the genus Karstsinnectes,namely K.cehengensis Luo,Zhao&Zhou,sp.nov.,collected from the Beipanjiang River,the upstream of the Hongshui River.Genetically,the four individuals of the new species form a phylogenetically separate lineage,as the sister clade of K.acridorsalis,with a 9.4–9.5%genetic difference in mitochondrial Cyt b.Morphologically,the new species can be distinguished from its congeners by a combination of the following morphological characteristics:body naked,without body color;eyes reduced,diameter 1.4–3.8%of head length;anterior and posterior nostrils adjacent,anterior nostril not elongated to a barbel-like tip;lateral line incomplete;caudal fin forked;dorsal-fin rays iii-7,pectoral-fin rays i-11–12,pelvic-fin rays i-7,anal-fin rays iii-5,with 14 branched caudal-fin rays.The discovery of this new species represents the northernmost distribution of species within the genus Karstsinnectes and the first record from Guizhou Province.All currently known species of this genus inhabited in caves,making them ideal organisms for studying historical river connectivity and cave formation process.

Stability evaluation of the Gümüshane-Akcakale cave by numerical analysis method

The Ak?akale Cave is located in the vicinity of the Arsa neighborhood within the boundaries of the Ak?akale village, Gümü?hane, Turkey. The cave is rich in cave formations(stalactite, stalagmite, cave pearl, cave flower, wall travertines). Thus, the appropriateness of opening the cave to visitors to boost tourism is of importance for the local and national economy. This study analyzes the stability of the Ak?akale Cave using a numerical analysis method. According to the results of the total displacement analysis, there are displacements in the entrance, ceiling, and sidewalls of the cave ranging from 1 mm to 48 mm. It seems that the entrance, ceiling, and sidewalls of the cave face a high risk of local or sudden collapse. According to the deformation analysis of the length section of the cave examined, local collapses may occur especially in the first 75 m from the entrance of the cave. We believe that this situation would not carry a risk for the Arsa neighborhood for now. In conclusion, the results of the stability analysis and in-situ observations showed clear evidence of former and ongoing cave-ins(collapses) and the Ak?akale Cave faces a high risk of local or sudden collapse. Thus, although the Ak?akale Cave is one of the most prominent karst caves in Turkey, it seems to be not appropriate to open the cave to tourist visits.

Characteristics of Breccias and C-O-Sr-S Isotope Geochemistry of the Duocaima Pb-Zn Deposit in Tuotuohe, Qinghai Province: Implications for the Ore-forming Process

The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely developed breccias, and the ore-forming process have been carefully studied based on geological documentation of drilling holes, microscopic observations of petrography and microstructure and some stable isotope measurements.Based on the compositions of the clast and matrix, the breccias can be classified into three types： limestone clasts cemented by marl; limestone clasts with fine-grained calcareous materials; and limestone clasts cemented by hydrothermal calcite.The mineralization in the first type of breccia is weak, whereas it is strong in the latter two types of breccias.According to the locations of occurrence and structural characteristics of the breccias along with the relationship between the breccias and mineralization, part of the limestone clasts that are cemented by marl and outcrop in the contact zone between the Wudaoliang Formation（Nw） and the underlying Jiushidaoban Formation（Pj） are attributed to synsedimentary fault-genetic breccia, whereas the last of the limestone clasts that are cemented by marl and developed in the Jiushidaoban Formation（Pj） are attributed to the breccia generated by karst cave collapse; the limestone clasts with fine-grained calcareous materials and the limestone clasts cemented by hydrothermal calcite are attributed to breccia formed by hydrothermal dissolution.The breccia formed by karst collapse had consistently evolved for a long period of time, while the breccias with other origins were formed around the period of mineralization（i.e., about or slightly later than 20–16 Ma）.The breccia generated by karst cave collapse and hydrothermal dissolution are somewhat related; the formation of the breccia from karst cave collapse provided open space for the later mineralization and reaction between hydrothermal fluids and host rocks, and the subsequent strong dissolution by hydrothermal fluids transformed some of the breccia formed earlier by karst cave collapse.Meanwhile, carbonate host rocks with breccias and brecciaed mineralization can be a potential sign of Mississippi Valley Type（MVT） deposits and important indicators for regional mineral exploration.The δ13CV-PDB, δ18OVSMOW, and 87Sr/86 Sr values of hydrothermal calcite in the Duocaima deposit range from 4.3‰ to 7.1‰, 14.9‰ to 20.1‰, and 0.707494 to 0.708185, respectively; the δ13CV-PDB, δ18OV-SMOW, and 87Sr/86 Sr values of the host limestones of the Jiushidaoban Formation range from 3.6‰ to 5.3‰, 18.0‰ to 20.5‰, and 0.707372 to 0.707945, respectively.The δ13CV-PDB and 87Sr/86 Sr values of hydrothermal calcite and limestone are similar, indicating single sources of C and Sr in this deposit, with the likely source being the limestone of the Jiushidaoban Formation.The minor scattering of the δ18OV-SMOW values suggests that different O isotope fluids underwent the isotope exchange reaction.The C-O-Sr isotope characteristics indicate that the host limestones experienced a dissolution and precipitation process during mineralization, which is beneficial to improving the porosity of host rocks and promoting the precipitation of metal sulfides.The δ34SV-CDT value of the breccia-type mineralization sulfides ranges from-30.4‰ to-0.3‰; that is, the δ34SV-CDT value is negative with considerable variation, illustrating that during the breccia-type mineralization process, the bacteriogenic reduction of sulfates provided the vast majority of sulfur, whereas the thermochemical reduction of sulfates was relatively unimportant.The brecciation that occurred as a result of karst cave collapse was mainly generated by the dissolution of groundwater; however, the brecciation related to hydrothermal dissolution and mineralization processes were caused by mixing of different fluids.

A New Species of Odorous Frog Genus Odorrana(Anura,Ranidae) from Southern Guizhou Province,China

We describe Odorrana liboensis sp.nov.,a new species from the Maolan National Nature Reserve,Libo County,Guizhou Province,China.Phylogenetic analyses based on DNA sequences of the mitochondrial 12 S rRNA,16 S rRNA,and ND2 genes supported the new species as an independent lineage,closely related to O.lipuensis.The uncorrected genetic distances between the 12 S rRNA and16 S rRNA in the new species and its closest congener,O.lipuensis,were 6.06%and 5.19%,respectively.The new species is distinguished from its congeners by a combination of the following morphological characters:(1)having medium body size,with the snout-vent length(SVL)of adult females approximately 1.2 times as long as males at 56.9±1.0(55.8-58.2 mm,n=9)in females and 48.7±1.2(47.1-49.9 mm,n=5)in males;(2)head length greater than width in males and females;(3)tympanum distinctly visible,greater than one-half the diameter of the eye;(4)eyes big and prominent,width of upper eyelid(UEW)approximately3/4 of eye diameter(ED);(5)dorsolateral folds absent;(6)two metacarpal tubercles;(7)relative finger lengths:Ⅱ<Ⅰ<Ⅳ<Ⅲ;(8)subarticular tubercles on fingers prominent:1,1,2,2;(9)one metatarsal tubercle;(10)tibiotarsal articulation reaching to between the eye and nostril when the leg is stretched forward;(11)toes with entire webbing to disks;(12)subarticular tubercles on toes prominent:1,1,2,3,2;(13)dorsal surfaces of limbs with distinct brownish-black bands;(14)smooth,grass-green dorsum with irregular brown mottling;(15)venter smooth,lacking black spots;and(16)lacking pectoral spinules,lacking vocal sacs,and light white nuptial pad present on finger I in males.The new species is currently only known from the type locality.

The spatial distribution and factors affecting karst cave development in Guizhou Province

This research examines the distribution features of 4960 caves across Guizhou Province, while probing the relationship between the caves＇ spatial patterns and geographic elements. This study is based on hydrogeological and topographic maps of Guizhou. ArcGIS software was used to process the adjacent index, spatial analysis, and coupling analysis of the caves altitude and longitude, as well as the rock properties, lithology, drainage and tec- tonic division of almost 5000 caves. Based on a point pattern analysis of Guizhou caves, the adjacent index is 0.53, and the coefficient of variation verified by Tyson polygon reached 72.469%. This figure reflects the clustered distribution pattern of the caves. Across the entire province, caves are divided into four concentrated areas and one weakly affected area. The four concentrated areas are Zunyi-Tongren, Bijie, Qianxinan-Liupanshui, and Gui- yang-Anshun-Qinan. The one weakly affected zone is Qiandongnan. The most concentrated among them is the Guiyang-Anshun-Qiannan area, which covers 24.67% of the total province area, and accounts for 36.63% of the total province＇s caves. Cave distribution in Guizhou is characterized as dense in the western part and sparse in the eastern part. Under this study background, the natural elements of formation, including lithology, structure, climate, hydrol- ogy, and altitude, and their effects on the distribution, number, and spatial pattern of cave development is analyzed.

Zinc phosphate dissolution by bacteria isolated from an oligotrophic karst cave in central China

Biogeochemical processes are fundamental to sustain the ecosystem in subsurface caves, but to date they are still far from well understood. To investigate micro-bially mediated phosphorus and zinc cycles, we isolated three bacterial strains from the dripping water in Heshang cave, central China, identified as Exiguobacterium aurantiacum E11, Pseudomonas fluorescens P35, and Pseu- domonas poae P41, respectively. Microbial capabilities in the dissolution of phosphorus-containing minerals were tested with zinc phosphate （Zn3（PO4）2） in batch culture at 30~C. A spectrophotometer, atomic absorption spectrum, and scanning electronic microscopy were used to measure the microbial growth, soluble Zn（II） concentration, and to observe the morphology of Zn3（PO4）2 before and after microbial dissolution. P. fluorescens and P. poae, the well- known phosphorus solubilizing bacteria （PSB）, are observed to solubilize Zn3（PO4）2 with an efficiency of 16.7% and 17.6%, respectively. To our knowledge, E. aurantiacum is firstly reported in this study to dissolve phosphorous-containing minerals with a higher efficiency of 39.7%, expanding our understanding about the ubiquitous occurrence of PSB in natural environments. Aqueous Zn（II） concentration positively correlates with H＋ activity, confirming the presence of acidification mechanisms widely exploited by PSB. Few itching pits were observed on the surface of Zn3（PO4）2 after microbial dissolution, inferring that microbial dissolution is not always associated with the direct contact with minerals. Even though the soluble Zn（II） concentration reached up to 370 mg/L in the system inoculated with E. aurantiacum Ell, inhibition of microbial growth was not detected by spectrophotometer. Our laboratory data revealed the importance of microbially-mediated P and Zn cycles in the subsurface ecosystem.

Analysis of the Mechanism of Water Inrush Geohazards in Deep-Buried Tunnels under the Complex Geological Environment of Karst Cave-Fractured Zone

To study the mechanism and evolution process of water inrush geohazards under the complex geological environment of the karst cave-fractured zone,a large-scale physical threedimensional(3 D)model test was first performed.Then the conceptual model for the evolution process of water inrush geohazards and the simplified theoretical model for the critical hydraulic pressure were both established based on the main characteristics of the water inrush geohazard in the engineering background and that in the model test.A new method was developed for modeling the geological environment of the karst cave-structural plane,and two formulae describing the critical water pressure of water inrush geohazards under two failure models of tensile-shear fracture failure and compressionshear fracture failure were also deduced based on fracture mechanics.The results showed that:(1)the evolution process of the water inrush geohazard can be divided into four stages,which include the initial balance,the propagation of original cracks,the formation of the dominant water inrush channel,and the instability of the waterproof rock mass;(2)the suddenness of water inrush geohazards becomes stronger with the increase of the hydraulic pressure;(3)the calculated critical hydraulic pressure of water inrush geohazards is similar to the measured critical hydraulic pressure in the model test,which validated the accuracies of the theoretical model,and the failure model of water inrush geohazards in this research is compression-shear fracture failure.