Karst sinkholes with natural negative landform provide favorable conditions for the pumped storage reservoir construction for less excavation work.However,the construction of the reservoir would plug the natural karst...Karst sinkholes with natural negative landform provide favorable conditions for the pumped storage reservoir construction for less excavation work.However,the construction of the reservoir would plug the natural karst channels for water and air,which would cause remarkable air pressure in karst channels when the groundwater level fluctuates.A large laboratory simulation test was carried out to study the air pressure variation of a reservoir built on the karst sinkhole.The air pressure in the karst channel and inside the model was monitored during the groundwater rising and falling process.Result showed that the variation of air pressure in the karst channel and the surrounding rock exhibited a high degree of similarity.The air pressure increased rapidly at the initial stage of water level rising,followed by a slight decrease,then the air pressure increased sharply when the water level approached the top of the karst cave.The initial peak of air pressure and the final peak of air pressure were defined,and both air pressure peaks were linearly increasing with the water level rising rate.The negative air pressure was also analyzed during the drainage process,which was linearly correlated with the water level falling rate.The causes of air pressure variation in karst channels of a pumped storage reservoir built on the karst sinkhole were discussed.The initial rapid increase,then slight decrease and final sudden increase of air pressure were controlled by the combined effects of air compression in karst channel and air seepage into the surrounding rock.For the drainage process,the instant negative air pressure and gradual recovering of air pressure were controlled by the combined effects of negative air pressure induced by water level falling and air supply from surrounding rock.This work could provide valuable reference for the reservoir construction in karst area.展开更多
Based on the arable land situation in Gejiu City,upland dry planting of indica hybrid rice is being expanded in Karst mountain areas with a rainfall of over 1400 mm and an altitude of 1100-1600 m to develop grain prod...Based on the arable land situation in Gejiu City,upland dry planting of indica hybrid rice is being expanded in Karst mountain areas with a rainfall of over 1400 mm and an altitude of 1100-1600 m to develop grain production.This paper gives a specific description of hybrid rice upland dry seedling technology,upland transplanting technology,fertilization technology,field management,weed prevention and control technology,and disease and pest control.展开更多
[Objective]The ecological vulnerability and landscape ecological risk of karst mountainous areas have increased as a result of enhanced disturbance of natural resources by human activities.This paper aimed to explore ...[Objective]The ecological vulnerability and landscape ecological risk of karst mountainous areas have increased as a result of enhanced disturbance of natural resources by human activities.This paper aimed to explore the characteristics of ecological risk evolution under different landscape patterns in the region,with a view to providing reference for land classification protection,sustainable use of resources and regional ecological risk optimization in karst mountainous areas.[Method]Taking Huangping County,a typical karst mountainous area,as an example,eight evaluation factors of natural and landscape patterns were selected to construct a landscape ecological risk evaluation model,to quantitatively explore the spatio-temporal evolution of landscape ecological risk and the trend of risk level transfer in the study area from 2010-2018,and to reveal the complex relationship between ecological risk and topography in karst mountainous areas.[Result]①From 2010 to 2018,land use types changed to different degrees,with the most amount of woodland transferred out(1627.37 hm 2)and the most amount of construction land transferred in(1303.93 hm 2);a total of 3552.31 hm 2 of land was transferred,with a change ratio of 2.13%,and there was a significant conversion between construction land,arable land,and woodland.②From 2010 to 2018,the landscape ecological risk in the study area changed significantly,and the landscape ecological risk index decreased from 0.3441 to 0.1733,showing an upward and then downward trend;the landscape ecological risk of the whole region was dominated by low-risk and lower-risk zones,and the ecological risk level generally shifted from a high level to a low level,and the ecological environment was improved.③There was a negative correlation between ecological risk and topographic position,and high-risk zones were mainly distributed among low topographic zones;with the change of time,the advantage of risk level for the selection of topography was gradually weakened,and the influence of anthropogenic factors on the ecological risk of the landscape was becoming more and more prominent.[Conclusion]This paper can provide theoretical basis for land use optimization and ecological protection in karst mountainous areas.展开更多
Karst groundwater is highly vulnerable to contamination,which urges better land use zoning.This paper proposes a new approach,called COCKPIT-PLUS,to minimize groundwater contamination within cockpit karst regions.The ...Karst groundwater is highly vulnerable to contamination,which urges better land use zoning.This paper proposes a new approach,called COCKPIT-PLUS,to minimize groundwater contamination within cockpit karst regions.The method employed four parameters:P(the existence of ponor/swallow hole),L(lineament density),U(sinking stream to an underground river),and S(distance to spring/pumping site).These parameters are essential for identifying contaminant pathways and transport from the surface to the karst groundwater/springs.COCKPIT-PLUS has been developed and validated in the Gunungsewu karst in Java,Indonesia.This research considers a cockpit as a single hydrological unit that uniquely recharges karst groundwater.We analyzed 2,811 cockpits and 81 other closed depressions to develop a land use planning map.The research used the time to first arrival(Ta),time to peak(Tp),and Q_(max/min)ratio parameters of two karst springs and two underground pumping sites for validation.Cockpits with ponors/swallow holes,sinking streams,high lineament density,and short distances to springs are vulnerable to groundwater and thus must be restricted areas for any land uses.The findings show that though the COCKPIT-PLUS uses a limited karst dataset,the proposed method seems reliable enough for a rapid land-use zoning approach in cockpit karst areas.展开更多
Humin(HM) is the main organic matter component to af fect the migration and transformation of polycyclic aromatic hydrocarbons(PAHs) in soil. The study on infl uence of the morphology change of inorganic ions on the a...Humin(HM) is the main organic matter component to af fect the migration and transformation of polycyclic aromatic hydrocarbons(PAHs) in soil. The study on infl uence of the morphology change of inorganic ions on the adsorption of PAHs in soil and its organic matter is still rare at microscopic scale. In this paper, yellow soil humin(YS-HM) and lime soil humin(LS-HM) were chosen as samples, then Fe^(3+) and Ca^(2+) were added into samples to facilitate the precipitation by changing the existing conditions of ions, and the mechanism by which inorganic precipitation changed adsorption capacity of karst soil was analyzed from the microscopic scale. The results showed that the adsorption capacity of HM reduced with the inorganic precipitation increasing. The precipitation of Ca^(2+)and Fe^(3+) both reduced the adsorption capacity of YS-HM and LS-HM by 61.71% and 71.83% on average, respectively. The results of scanning electron microscope-energy dispersive spectrometry(SEM-EDS) and pore analysis showed that the HM porosity decreased after formation of Ca^(2+) and Fe^(3+) precipitation. According to the value of Freundlich parameter n, it may be because the precipitation or colloid of Ca^(2+) and Fe^(3+) fi lled micropores and covers high-energy adsorption sites of the HM. This research provides theoretical support for studying the PAHs migration and bioavailability of Calcium-rich in karst soil.展开更多
Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests(EBLFs),with distribution centers in the karst regions of Yunnan,Guizhou,and Guangxi in southwestern...Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests(EBLFs),with distribution centers in the karst regions of Yunnan,Guizhou,and Guangxi in southwestern China.Based on the hemiparasitic and more or less liana habits of this genus,we hypothesized that its evolution and distribution were shaped by the development of EBLFs there.To test our hypothesis,the most comprehensive phylogenies of Brandisia hitherto were constructed based on plastome and nuclear loci(nrDNA,PHYA and PHYB);then divergence time and ancestral areas were inferred using the combined nuclear loci dataset.Phylogenetic analyses reconfirmed that Brandisia is a member of Orobanchaceae,with unstable placements caused by nuclear-plastid incongruences.Within Brandisia,three major clades were well supported,corresponding to the three subgenera based on morphology.Brandisia was inferred to have originated in the early Oligocene(32.69 Mya)in the Eastern Himalayas-SW China,followed by diversification in the early Miocene(19.45 Mya)in karst EBLFs.The differentiation dates of Brandisia were consistent with the origin of keystone species of EBLFs in this region(e.g.,Fagaceae,Lauraceae,Theaceae,and Magnoliaceae)and the colonization of other characteristic groups(e.g.,Gesneriaceae and Mahonia).These findings indicate that the distribution and evolution of Brandisia were facilitated by the rise of the karst EBLFs in East Asia.In addition,the woody and parasitic habits,and pollination characteristics of Brandisia may also be the important factors affecting its speciation and dispersal.展开更多
Soil erosion is a prominent environmental problem in karst regions.Exploring the spatiotemporal variability of soil erosion and the factors that influence soil erosion is of great significance for regional soil erosio...Soil erosion is a prominent environmental problem in karst regions.Exploring the spatiotemporal variability of soil erosion and the factors that influence soil erosion is of great significance for regional soil erosion prevention and control.However,the mechanisms influencing the characteristic features of the karst basins,such as bedrock exposure and lithology,still need to be further explored.This study used GIS technology,the Revised Universal Soil Loss Equation model,Getis–Ord Gi*,and partial least squares regression(PLSR)to identify the dominant factors influencing soil erosion and the spatiotemporal variability of soil erosion in 31 sub-basins of the Dabang River Basin(DRB),a typical karst area of Southwest China,from 2010 to 2020.The results indicated that soil erosion in the DRB from 2010 to 2020 was generally decreasing,the mean soil erosion in the DRB in 2010,2015 and 2020 was 18.46,16.51 and 15.29 t ha^(-1)a^(-1),respectively.During the study period,the area of slight erosion increased by 26.39%(706.54 km^(2)),while severe erosion enlarged by 26.36 km^(2).Spatially,the DRB was primarily affected by medium and slight soil erosion.The hot spot areas of soil erosion(key control areas)were mainly concentrated in the central and southern parts of the basin,decreasing each year,and the area of soil erosion hot pots has decreased from 43.22%to 20.60%.PLSR decoupling results show that elevation,bedrock exposure,land use type,interbedded limestone and clastic rock,and vegetation coverage were identified as the key variables affecting soil erosion,explaining 52.8%of soil erosion variability,with a high value of the Variable Importance on Projection(VIP)more than 1.These results can be used as a reference for comprehensive control of soil erosion and water loss in the basin.展开更多
Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine...Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine community assembly have not been studied in the karst region of southwest China.In this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly.Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role.Overall interpretation rate increases with enlarging the sampling scale.However,the pattern of variation partitioning was similar in different life stages.Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling sizes.Topographic wetness index was the most important variable to explain species composition of the environmental variables.These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.展开更多
Droughts are recurrent in southwest China due to the fragility and sensitivity of the karst environment.These events have serious impacts on local agricultural output,ecological diversity,and social stability.Understa...Droughts are recurrent in southwest China due to the fragility and sensitivity of the karst environment.These events have serious impacts on local agricultural output,ecological diversity,and social stability.Understanding spatiotemporal variations and driving factors of drought in this area is of extreme importance for effective mitigation measures.The karst areas situated in southwest China were spatially divided into seven sub-regions according to the topography and degree of karst development.Drought indices,including vegetation condition index(VCI),temperature condition index(TCI),vegetation health index(VHI),normalized vegetation water supply index(NVSWI),and temperature vegetation drought index(TVDI),were calculated from MODIS data during 2000 and 2018for each sub-region,and drought patterns were examined.The results show that droughts were found to be concentrated in sub-regions such as karst basin,karst plateau,karst gorge,and karst depression areas.Furthermore,there were more drought conditions in karst areas than in non-karst areas.In addition,improvements to drought situation in the study period are significant(p<0.05),and mitigation areas respectively account for 80.1%(NVSWI),74.2%(VCI),74.2%(VHI),30.1%(TCI)and 33.2%(TVDI)of the study area,while drought expands slightly(<3.4%)in areas undergoing urban construction.Pearson's correlation coefficients between drought indices and temperature are generally above 0.5 in all sub-regions.However,the correlation coefficients between drought indices and precipitation mostly fall within the range of 0.3-0.4,indicating a weaker correlation.Our explanation for the spatiotemporal patterns of drought is that karst phenomena are the natural basis of drought and agricultural production is one of important driving forces.Positive changes of drought conditions have benefited from efforts to control rocky desertification and restore ecosystems over the past years.展开更多
In karst areas,the drainage pipes of aging tunnels are prone to be clogged by precipitated carbonates,resulting in lining cracking and tunnel leaking.As a result,not only the driving safety will be deteriorated,but al...In karst areas,the drainage pipes of aging tunnels are prone to be clogged by precipitated carbonates,resulting in lining cracking and tunnel leaking.As a result,not only the driving safety will be deteriorated,but also the water pressure on the lining might also be elevated significantly.For the structural stability and service lifespan of old tunnels,it is of great importance to remove these precipitated carbonates in time.Traditional treatment methods are often destructive to some extent or not efficient enough.This study aims to experimentally develop an eco-friendly acid-based chemical cleaning method to remove carbonate precipitations efficiently.The proposed chemical cleaning agent is an aqueous solution with strong acidity,consisting of sulfamic acid,water,and additives.The factors affecting the cleaning efficiency include the acid solubility,temperature and flow rate of the cleaning agent,as well as additives.Elevating the solution temperature to 50C or a flow rate of no less than 0.2 m/s can improve cleaning efficiency.Although the salt effect cannot work,1 wt%of polymaleic acid as a surfactant could further promote the cleaning rate.The cleaning efficiency will increase with the flow rate in a power function.The relatively low flow rate that improves the cleaning rate considerably can avoid highpressure-induced mechanical damage to tunnel drainpipes.The waste could be easily treated to acceptable levels using commercial sewage treatment products and can also be recycled in agriculture.With the chemical cleaning,the water pressure at the arch springing of the lining will reduce with the increased radius of transverse drainpipes in a power function.The proposed acid-based cleaning method,which is highly efficient,non-or low-destructive to aging tunnels,sufficiently safe for humans,and friendly enough to the environment,will offer a promising alternative to remove the precipitated carbonates in tunnel drainpipes efficiently.展开更多
Carbonate rocks, as soluble rocks, will dissolve and experience karstification driven by flowing water. This process consumes CO_(2)from the air and converts atmospheric CO_(2) and CO_(3)^(2-)of rocks into HCO_(3)^(-)...Carbonate rocks, as soluble rocks, will dissolve and experience karstification driven by flowing water. This process consumes CO_(2)from the air and converts atmospheric CO_(2) and CO_(3)^(2-)of rocks into HCO_(3)^(-), resulting in the transfer of carbon from the atmosphere to the hydrosphere. Part of those dissolved HCO3-in the groundwater and surface water will degrade as CO_(2) and return to the atmosphere.展开更多
Settlements and cultivated land are important production and living spaces in promoting rural revitalization.However,few studies have explored the relationship between rural settlements and cultivated land from spatio...Settlements and cultivated land are important production and living spaces in promoting rural revitalization.However,few studies have explored the relationship between rural settlements and cultivated land from spatiotemporal interaction perspective.This paper analyzed the spatiotemporal conversion and the interactive mechanism between rural settlements and cultivated land in a karst mountainous area(Qixingguan District of Guizhou Province)with fragile ecological environment in China during 2009–2018.The results showed that the expansion of rural settlements and the loss of cultivated land coexisted in Qixingguan District.Only 2.68%of the new cultivated land was reclaimed from rural settlements,whereas 85.45%of the new rural settlements occupied cultivated land.Six spatial expansion modes of rural settlements when occupying cultivated land were identified.Among these six modes,the area of the edge-expansion&along traffic roads(EA)mode accounted for 52.75%.The occupation by rural settlements made the cultivated land landscape more fragmented.The area ratio index of cultivated land to rural settlements(ARICR)of Qixingguan District averaged 18.75in 2009 and 17.21 in 2018,respectively.The ARICR reduced in all township administrative regions.Cultivated land with suitable slope condition for farming or without rocky desertification was more likely to be occupied by rural settlements.The probability of cultivated land occupied by rural settlements increased with the decrease of the distance to traffic roads,towns,and old rural settlements.The better the economic and social development of the township administrative regions,the more the ARICR decreased,while the richer the agricultural resources and the better the rural development of the township administrative regions,the less the ARICR decreased.The optimal reconstruction path of rural settlements,the comprehensive conservation path of cultivated land and the urban-rural integration development path in karst mountainous area were proposed.The findings would contribute to our understanding of the spatiotemporal interaction between rural settlements and cultivated land,and would provide a theoretical basis for promoting the coordinated development of rural man-land relationship and rural revitalization in karst areas.展开更多
In recent years,karst construction projects in the built-up area of Wuhan(capital of Hubei Province,China)are increasing,and the karst geological disasters have aroused social concerns.The actual engineering projects ...In recent years,karst construction projects in the built-up area of Wuhan(capital of Hubei Province,China)are increasing,and the karst geological disasters have aroused social concerns.The actual engineering projects usually use shallow geophysical exploration methods to explore karst.This paper uses Spatial Auto-Correlation Method(SPAC)and electromagnetic Computerized Tomography(CT)to detect karst in urban built-up areas.Depending on the different physical properties of rock and soil,the SPAC method can better reveal the interface between soil and rock strata and the interface between soil layers.The electromagnetic CT method can identify strata according to the apparent absorption coefficient,which can better reveal the interface between soil and rock,the interface between the more intact and weathered rock.The SPAC method is mainly qualitative to measure the low-speed area,namely,the wrong geological body i.e.,karst cave,but also can detect the fracture zone or filling mode of karst cave,and at the same time,cannot use exploration holes or logging observation.The electromagnetic CT method can accurately detect the location and scale of the karst caves and has a higher accuracy detecting karst bands.In addition,exploration holes or well logging observations are also expected to be conducted,and their detection effect is greatly affected by lithology.展开更多
A comprehensive study was undertaken at Jiaozi coal mine to investigate the development regularity of ground fissures in shallow buried coal seam mining with Karst landform,shedding light on the development type,geogr...A comprehensive study was undertaken at Jiaozi coal mine to investigate the development regularity of ground fissures in shallow buried coal seam mining with Karst landform,shedding light on the development type,geographical distribution,dynamic development process,and failure mechanism of these ground fissures by employing field monitoring,numerical simulation,and theoretical analysis.The findings demonstrate that ground fissure development has an obvious feature of subregion,and its geographical distribution is significantly affected by topography.Tensile type,open type,and stepped type are three different categories of ground fissure.Ground fissures emerge dynamically as the panel advances,and they typically develop with a distance of less than periodic weighting step distance in advance of panel advancing position.Ground fissures present the dynamic development feature,temporary fissure has the ability of self-healing.The dynamic development process of ground fissure with closed-distance coal seam repeated mining is expounded,and the development scale is a dynamic development stage of“closure→expansion→stabilized”on the basis of the original development scale.From the perspective of topsoil deformation,the computation model considering two points movement vectors towards two directions of the gob and the ground surface is established,the development criterion considering the critical deformation value of topsoil is obtained.The mechanical model of hinged structure of inclined body is proposed to clarify the ground fissure development,and the interaction between slope activity and ground fissure development is expounded.These research results fulfill the gap of ground fissures about development regularity and formation mechanism,and can contribute to ground fissure prevention and treatment with Karst landform.展开更多
Mapping abandoned land is very important for accurate agricultural management.However,in karst mountainous areas,continuous high-resolution optical images are difficult to obtain in rainy weather,and the land is fragm...Mapping abandoned land is very important for accurate agricultural management.However,in karst mountainous areas,continuous high-resolution optical images are difficult to obtain in rainy weather,and the land is fragmented,which poses a great challenge for remote sensing monitoring of agriculture activities.In this study,a new method for identifying abandoned land is proposed:firstly,a few Google Earth images are used to transform arable land into accurate vectorized geo-parcels;secondly,a time-series data set was constructed using Sentinel-1A Alpha parameters for 2020 on each farmland geoparcel;thirdly,the semi-variation function(SVF)was used to analyze the spatial-temporal characteristics,then identify abandoned land.The results show:(1)On the basis of accurate spatial information and boundary of farmland land,the SAR time-series dataset reflects the structure and time-series response.abandoned land with an accuracy of 80.25%.The problem of remote sensing monitoring in rainy regions and complex surface areas is well-resolved.(2)The spatial heterogeneity of abandoned land is more obvious than that of cultivated land within geoparcels.The step size for significant changes in the SVF of abandoned land is shorter than that of cultivated land.(3)The SVF time sequence curve presented a strong peak feature when farmland was abandoned.This reveals that the internal spatial structure of abandoned land is more disordered and complex.It showed that time-series variations of spatial structure within cultivated land have broader applications in remote sensing monitoring of agriculture in complex imaging environments.展开更多
Carbon dioxide(CO_(2))emissions from aquatic ecosystems are an important component of the karst carbon cycle process and also a key indicator for assessing the effect of karst carbon sinks.This paper reviewed the CO_(...Carbon dioxide(CO_(2))emissions from aquatic ecosystems are an important component of the karst carbon cycle process and also a key indicator for assessing the effect of karst carbon sinks.This paper reviewed the CO_(2)partial pressure(pCO_(2))and its diffusion flux(FCO_(2))in karst surface aquatic ecosystems,mainly rivers,lakes,and reservoirs,and their influencing factors summarized the methods for monitoring CO_(2)emissions in karst aquatic ecosystems and discussed their adaptation conditions in karst areas.The pCO_(2)and FCO_(2)decreased in the order of rivers>reservoirs>lakes,and the values in karst lakes were eventually significantly lower than those in global lakes.The pCO_(2)and FCO_(2)of karst aquatic ecosystems had patterns of variation with diurnal,seasonal,water depth and hydrological cycles,and spatial and temporal hetero-geneity.The sources of CO_(2)in karst waters are influenced by both internal and external sources,and the key spatial and temporal factors affecting the CO_(2)emissions from karst rivers,lakes,and reservoirs were determined in terms of physicochemical indicators,biological factors,and bio-genic elements;additionally,the process of human activity interference on CO_(2)emissions was discussed.Finally,a conceptual model illustrating the impacts of urban devel-opment,agriculture,mining,and dam construction on the CO_(2)emissions at the karst surface aquatic ecosystem is presented.Meanwhile,based on the disadvantages existing in current research,we proposed several important research fields related to CO_(2)emissions from karst surface aquatic ecosystems.展开更多
This experiment examined the fluctuations in nitrogen gas supersaturation throughout the day in three karst springs (upper, side, and lower) at McNenny State Fish Hatchery, rural Spearfish, Lawrence County, South Dako...This experiment examined the fluctuations in nitrogen gas supersaturation throughout the day in three karst springs (upper, side, and lower) at McNenny State Fish Hatchery, rural Spearfish, Lawrence County, South Dakota, USA. Total gas pressures, oxygen percent saturation, and nitrogen percent saturation were recorded six times/day on eight days over a 26-day period in each of the three springs. Total gas pressure did not vary significantly throughout the day in any of the springs. However, percent oxygen and nitrogen saturation were significantly different throughout the day in all three springs. The highest mean (SE) nitrogen supersaturation value of 118.5 (1.1)% was observed in the lower spring at 07:00. The lowest mean nitrogen supersaturation values were 114.5 (1.1)% at 13:00 in the upper spring, and 114.2 (0.2)% and 113.1 (0.7)% at 15:00 in the side and lower spring, respectively. At 118% nitrogen supersaturation, gas bubble disease is likely to occur in fish, resulting in potentially high levels of mortality if untreated spring water was used for fish production. The results of this study indicate the importance of recording nitrogen gas levels at sunrise or early in the morning, when nitrogen is highest and oxygen is lowest, to obtain accurate and reproducible data.展开更多
An analysis of the formation of karst and karst-suffosion forms on the territory of the West Kazakhstan region is presented in this paper. Numerous literary sources were used as the information database for the analys...An analysis of the formation of karst and karst-suffosion forms on the territory of the West Kazakhstan region is presented in this paper. Numerous literary sources were used as the information database for the analysis of the relief features of the West Kazakhstan region. Evaluation of the morphometric features of the collapsed new formations on the basis of materials of our own field research is presented here for the first time. According to the research objectives there were defined localization places of the karst-collapsed phenomena where the reconnaissance field surveys were carried out. Survey points’ localization has been carried out by means of GPS system with the help of 12-channel GPS-receiver of Garmin eTrex model. Geoinformational technology, based on MapInfo 9.5 and ArcGIS 9.2 packages was used for the building of the information and cartographic database. Original thematic maps compiled on the basis of the research results’ analysis have been obtained in this research. The features of the Caspian Basin’s karst landscapes, formed as a result of salt-dome tectonic manifestations (Inder Mountains, Malaya Bogdo Mountain, Bish-Chokho hill) are described in this paper. The important elements of the Caspian Basin salt-dome landscapes are landforms of the karst origin from large karst depressions of the karst-tectonic origin to modern forms of the sulfate karst: sinkholes, wells, polje, knobs (“Kurgantau”), arches, caves and grottoes. Some karst formations have a non-salt-dome origin. Three areas with the collapsed forms that have the karst-suffosion origin have been identified (near Konyr village, Berezovka village and Zhanatalap village). The mechanism of the sinkholes formation is due to the changes of the groundwater regime and the displacement of limestone eluvium as a result of active anthropogenic impacts. The sinkholes occurence near Zhanatalap village, which is located near the Karachaganak oil and gas field, is probably due to the anthropogenic initiation of karst-suffosion processes.展开更多
As highways are extended to deep mountains,high altitudes,and special geological conditions,tunnel construction becomes more and more challenging,especially the construction of tunnels in karst areas.Due to the partic...As highways are extended to deep mountains,high altitudes,and special geological conditions,tunnel construction becomes more and more challenging,especially the construction of tunnels in karst areas.Due to the particularity of the regional geological structure,karst is well developed in the southwest of our country,especially at areas where the problem of tunnel water inrush in karst areas is more prominent.To further ensure the safe construction and operation of tunnels,the characteristics of tunnels in karst areas is analyzed in this article.展开更多
Water inrush,which is one of the challenging issues and hot topics in the tunneling industry,is very easy to occur during the construction of karst tunnels.The mechanism of water inrush of karst tunnels is discussed a...Water inrush,which is one of the challenging issues and hot topics in the tunneling industry,is very easy to occur during the construction of karst tunnels.The mechanism of water inrush of karst tunnels is discussed and analyzed in the paper:the water inrush of karst tunnels is generally divided into three steps,i.e.,the forming of the hazard source,the forming of the water inrush passage and the failure of the anti-inrush rock mass.The failure of the anti-inrush rock mass of karst tunnels are classified into 5 types,i.e.,the integral tensile-shear failure,the hydraulic fracturing,the infiltration induced sliding of the filling medium,the loss of key blocks and the comprehensive water inrush mode.The failure mechanism is studied on basis of typical cases and by means of numerical simulation or theoretical analysis.Conclusion is drawn that most of the water inrushes in actual tunneling are comprehensive water inrushes,which are the comprehensive results of the interrelation and interaction of various water inrush types,and that different types of water inrushes have related continuity and progressive evolution relationships under certain conditions.展开更多
基金support from the National Natural Science Foundation of China(Grant.No.42162027)the Science and technology foundation of Guizhou Province(Grant.No.2022-212,2023-006)are greatly appreciated.
文摘Karst sinkholes with natural negative landform provide favorable conditions for the pumped storage reservoir construction for less excavation work.However,the construction of the reservoir would plug the natural karst channels for water and air,which would cause remarkable air pressure in karst channels when the groundwater level fluctuates.A large laboratory simulation test was carried out to study the air pressure variation of a reservoir built on the karst sinkhole.The air pressure in the karst channel and inside the model was monitored during the groundwater rising and falling process.Result showed that the variation of air pressure in the karst channel and the surrounding rock exhibited a high degree of similarity.The air pressure increased rapidly at the initial stage of water level rising,followed by a slight decrease,then the air pressure increased sharply when the water level approached the top of the karst cave.The initial peak of air pressure and the final peak of air pressure were defined,and both air pressure peaks were linearly increasing with the water level rising rate.The negative air pressure was also analyzed during the drainage process,which was linearly correlated with the water level falling rate.The causes of air pressure variation in karst channels of a pumped storage reservoir built on the karst sinkhole were discussed.The initial rapid increase,then slight decrease and final sudden increase of air pressure were controlled by the combined effects of air compression in karst channel and air seepage into the surrounding rock.For the drainage process,the instant negative air pressure and gradual recovering of air pressure were controlled by the combined effects of negative air pressure induced by water level falling and air supply from surrounding rock.This work could provide valuable reference for the reservoir construction in karst area.
文摘Based on the arable land situation in Gejiu City,upland dry planting of indica hybrid rice is being expanded in Karst mountain areas with a rainfall of over 1400 mm and an altitude of 1100-1600 m to develop grain production.This paper gives a specific description of hybrid rice upland dry seedling technology,upland transplanting technology,fertilization technology,field management,weed prevention and control technology,and disease and pest control.
基金the National Natural Science Foundation of China(41661088)Project for Guizhou Province"High-level Innovative Talent Training Program‘Hundred’Level Talents"(QKHPTRC[2016]5674)Guizhou Science and Technology Plan Project(QKHZC[2023]GENERAL211).
文摘[Objective]The ecological vulnerability and landscape ecological risk of karst mountainous areas have increased as a result of enhanced disturbance of natural resources by human activities.This paper aimed to explore the characteristics of ecological risk evolution under different landscape patterns in the region,with a view to providing reference for land classification protection,sustainable use of resources and regional ecological risk optimization in karst mountainous areas.[Method]Taking Huangping County,a typical karst mountainous area,as an example,eight evaluation factors of natural and landscape patterns were selected to construct a landscape ecological risk evaluation model,to quantitatively explore the spatio-temporal evolution of landscape ecological risk and the trend of risk level transfer in the study area from 2010-2018,and to reveal the complex relationship between ecological risk and topography in karst mountainous areas.[Result]①From 2010 to 2018,land use types changed to different degrees,with the most amount of woodland transferred out(1627.37 hm 2)and the most amount of construction land transferred in(1303.93 hm 2);a total of 3552.31 hm 2 of land was transferred,with a change ratio of 2.13%,and there was a significant conversion between construction land,arable land,and woodland.②From 2010 to 2018,the landscape ecological risk in the study area changed significantly,and the landscape ecological risk index decreased from 0.3441 to 0.1733,showing an upward and then downward trend;the landscape ecological risk of the whole region was dominated by low-risk and lower-risk zones,and the ecological risk level generally shifted from a high level to a low level,and the ecological environment was improved.③There was a negative correlation between ecological risk and topographic position,and high-risk zones were mainly distributed among low topographic zones;with the change of time,the advantage of risk level for the selection of topography was gradually weakened,and the influence of anthropogenic factors on the ecological risk of the landscape was becoming more and more prominent.[Conclusion]This paper can provide theoretical basis for land use optimization and ecological protection in karst mountainous areas.
文摘Karst groundwater is highly vulnerable to contamination,which urges better land use zoning.This paper proposes a new approach,called COCKPIT-PLUS,to minimize groundwater contamination within cockpit karst regions.The method employed four parameters:P(the existence of ponor/swallow hole),L(lineament density),U(sinking stream to an underground river),and S(distance to spring/pumping site).These parameters are essential for identifying contaminant pathways and transport from the surface to the karst groundwater/springs.COCKPIT-PLUS has been developed and validated in the Gunungsewu karst in Java,Indonesia.This research considers a cockpit as a single hydrological unit that uniquely recharges karst groundwater.We analyzed 2,811 cockpits and 81 other closed depressions to develop a land use planning map.The research used the time to first arrival(Ta),time to peak(Tp),and Q_(max/min)ratio parameters of two karst springs and two underground pumping sites for validation.Cockpits with ponors/swallow holes,sinking streams,high lineament density,and short distances to springs are vulnerable to groundwater and thus must be restricted areas for any land uses.The findings show that though the COCKPIT-PLUS uses a limited karst dataset,the proposed method seems reliable enough for a rapid land-use zoning approach in cockpit karst areas.
基金The national natural science Foundations of China under Grant (41761091)The first-class discipline group of geography of Guizhou Province under Grant (N0.[2019]125)+3 种基金Youth Science and Technology Talents Growth Fund of Education Department of Guizhou Province,China (No.KY[2022] 001)Scientific Research Funds of Guiyang University,China (No.GYU-KY-[2022])The Joint Foundation of Guizhou Province under Grant (LH [2017]7348)The Doctor Foundation of Guizhou Normal University under Grant (GZNUD [2017]10)。
文摘Humin(HM) is the main organic matter component to af fect the migration and transformation of polycyclic aromatic hydrocarbons(PAHs) in soil. The study on infl uence of the morphology change of inorganic ions on the adsorption of PAHs in soil and its organic matter is still rare at microscopic scale. In this paper, yellow soil humin(YS-HM) and lime soil humin(LS-HM) were chosen as samples, then Fe^(3+) and Ca^(2+) were added into samples to facilitate the precipitation by changing the existing conditions of ions, and the mechanism by which inorganic precipitation changed adsorption capacity of karst soil was analyzed from the microscopic scale. The results showed that the adsorption capacity of HM reduced with the inorganic precipitation increasing. The precipitation of Ca^(2+)and Fe^(3+) both reduced the adsorption capacity of YS-HM and LS-HM by 61.71% and 71.83% on average, respectively. The results of scanning electron microscope-energy dispersive spectrometry(SEM-EDS) and pore analysis showed that the HM porosity decreased after formation of Ca^(2+) and Fe^(3+) precipitation. According to the value of Freundlich parameter n, it may be because the precipitation or colloid of Ca^(2+) and Fe^(3+) fi lled micropores and covers high-energy adsorption sites of the HM. This research provides theoretical support for studying the PAHs migration and bioavailability of Calcium-rich in karst soil.
基金funded by the Key Projects of the Joint Fund of the National Natural Science Foundation of China(U1802232)the national youth talent support program+2 种基金CAS"Light of West China"ProgramYunnan youth talent support program(YNWR-QNBJ-2018-183 to Y.N.)Vietnam Academy of Science and Technology(UQDTCB.06/22-23)。
文摘Brandisia is a shrubby genus of about eight species distributed basically in East Asian evergreen broadleaved forests(EBLFs),with distribution centers in the karst regions of Yunnan,Guizhou,and Guangxi in southwestern China.Based on the hemiparasitic and more or less liana habits of this genus,we hypothesized that its evolution and distribution were shaped by the development of EBLFs there.To test our hypothesis,the most comprehensive phylogenies of Brandisia hitherto were constructed based on plastome and nuclear loci(nrDNA,PHYA and PHYB);then divergence time and ancestral areas were inferred using the combined nuclear loci dataset.Phylogenetic analyses reconfirmed that Brandisia is a member of Orobanchaceae,with unstable placements caused by nuclear-plastid incongruences.Within Brandisia,three major clades were well supported,corresponding to the three subgenera based on morphology.Brandisia was inferred to have originated in the early Oligocene(32.69 Mya)in the Eastern Himalayas-SW China,followed by diversification in the early Miocene(19.45 Mya)in karst EBLFs.The differentiation dates of Brandisia were consistent with the origin of keystone species of EBLFs in this region(e.g.,Fagaceae,Lauraceae,Theaceae,and Magnoliaceae)and the colonization of other characteristic groups(e.g.,Gesneriaceae and Mahonia).These findings indicate that the distribution and evolution of Brandisia were facilitated by the rise of the karst EBLFs in East Asia.In addition,the woody and parasitic habits,and pollination characteristics of Brandisia may also be the important factors affecting its speciation and dispersal.
基金supported by National Natural Science Foundation of China(32060372,32360421)Guizhou Science and Technology Department(Qian Ke He Ji Chu ZK-[2023]Key 029Qiankehe Zhicheng[2021]Yiban462)。
文摘Soil erosion is a prominent environmental problem in karst regions.Exploring the spatiotemporal variability of soil erosion and the factors that influence soil erosion is of great significance for regional soil erosion prevention and control.However,the mechanisms influencing the characteristic features of the karst basins,such as bedrock exposure and lithology,still need to be further explored.This study used GIS technology,the Revised Universal Soil Loss Equation model,Getis–Ord Gi*,and partial least squares regression(PLSR)to identify the dominant factors influencing soil erosion and the spatiotemporal variability of soil erosion in 31 sub-basins of the Dabang River Basin(DRB),a typical karst area of Southwest China,from 2010 to 2020.The results indicated that soil erosion in the DRB from 2010 to 2020 was generally decreasing,the mean soil erosion in the DRB in 2010,2015 and 2020 was 18.46,16.51 and 15.29 t ha^(-1)a^(-1),respectively.During the study period,the area of slight erosion increased by 26.39%(706.54 km^(2)),while severe erosion enlarged by 26.36 km^(2).Spatially,the DRB was primarily affected by medium and slight soil erosion.The hot spot areas of soil erosion(key control areas)were mainly concentrated in the central and southern parts of the basin,decreasing each year,and the area of soil erosion hot pots has decreased from 43.22%to 20.60%.PLSR decoupling results show that elevation,bedrock exposure,land use type,interbedded limestone and clastic rock,and vegetation coverage were identified as the key variables affecting soil erosion,explaining 52.8%of soil erosion variability,with a high value of the Variable Importance on Projection(VIP)more than 1.These results can be used as a reference for comprehensive control of soil erosion and water loss in the basin.
基金supported by the National Natural Science Foundation of China (42071073,31971487)Youth Innovation Promotion Association of the Chinese Academy of Sciences (2021366)+2 种基金Guangxi Key Research and Development Program (AB17129009)the Hechi Distinguished Expert Program to Fuping Zengthe Guangxi Bagui Scholarship Program to Dejun Li。
文摘Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine community assembly have not been studied in the karst region of southwest China.In this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly.Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role.Overall interpretation rate increases with enlarging the sampling scale.However,the pattern of variation partitioning was similar in different life stages.Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling sizes.Topographic wetness index was the most important variable to explain species composition of the environmental variables.These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.
基金the Guangxi Natural Science Foundation(NO.2022GXNSFBA035639)the Natural Science Foundation of China(NO.42064003)the Guangxi Key Laboratory of Spatial Information and Geomatics Program(Gui KeNeng 19-050-11-23)。
文摘Droughts are recurrent in southwest China due to the fragility and sensitivity of the karst environment.These events have serious impacts on local agricultural output,ecological diversity,and social stability.Understanding spatiotemporal variations and driving factors of drought in this area is of extreme importance for effective mitigation measures.The karst areas situated in southwest China were spatially divided into seven sub-regions according to the topography and degree of karst development.Drought indices,including vegetation condition index(VCI),temperature condition index(TCI),vegetation health index(VHI),normalized vegetation water supply index(NVSWI),and temperature vegetation drought index(TVDI),were calculated from MODIS data during 2000 and 2018for each sub-region,and drought patterns were examined.The results show that droughts were found to be concentrated in sub-regions such as karst basin,karst plateau,karst gorge,and karst depression areas.Furthermore,there were more drought conditions in karst areas than in non-karst areas.In addition,improvements to drought situation in the study period are significant(p<0.05),and mitigation areas respectively account for 80.1%(NVSWI),74.2%(VCI),74.2%(VHI),30.1%(TCI)and 33.2%(TVDI)of the study area,while drought expands slightly(<3.4%)in areas undergoing urban construction.Pearson's correlation coefficients between drought indices and temperature are generally above 0.5 in all sub-regions.However,the correlation coefficients between drought indices and precipitation mostly fall within the range of 0.3-0.4,indicating a weaker correlation.Our explanation for the spatiotemporal patterns of drought is that karst phenomena are the natural basis of drought and agricultural production is one of important driving forces.Positive changes of drought conditions have benefited from efforts to control rocky desertification and restore ecosystems over the past years.
基金The financial support from the Fundamental Research Funds for the Central Universities,China(Grant No.YJ2021148)is gratefully acknowledged.The authors are also grateful to Prof.Ming Lü,a member of the Norwegian Academy of Technological Sciences from Norway,for his valuable suggestions.
文摘In karst areas,the drainage pipes of aging tunnels are prone to be clogged by precipitated carbonates,resulting in lining cracking and tunnel leaking.As a result,not only the driving safety will be deteriorated,but also the water pressure on the lining might also be elevated significantly.For the structural stability and service lifespan of old tunnels,it is of great importance to remove these precipitated carbonates in time.Traditional treatment methods are often destructive to some extent or not efficient enough.This study aims to experimentally develop an eco-friendly acid-based chemical cleaning method to remove carbonate precipitations efficiently.The proposed chemical cleaning agent is an aqueous solution with strong acidity,consisting of sulfamic acid,water,and additives.The factors affecting the cleaning efficiency include the acid solubility,temperature and flow rate of the cleaning agent,as well as additives.Elevating the solution temperature to 50C or a flow rate of no less than 0.2 m/s can improve cleaning efficiency.Although the salt effect cannot work,1 wt%of polymaleic acid as a surfactant could further promote the cleaning rate.The cleaning efficiency will increase with the flow rate in a power function.The relatively low flow rate that improves the cleaning rate considerably can avoid highpressure-induced mechanical damage to tunnel drainpipes.The waste could be easily treated to acceptable levels using commercial sewage treatment products and can also be recycled in agriculture.With the chemical cleaning,the water pressure at the arch springing of the lining will reduce with the increased radius of transverse drainpipes in a power function.The proposed acid-based cleaning method,which is highly efficient,non-or low-destructive to aging tunnels,sufficiently safe for humans,and friendly enough to the environment,will offer a promising alternative to remove the precipitated carbonates in tunnel drainpipes efficiently.
文摘Carbonate rocks, as soluble rocks, will dissolve and experience karstification driven by flowing water. This process consumes CO_(2)from the air and converts atmospheric CO_(2) and CO_(3)^(2-)of rocks into HCO_(3)^(-), resulting in the transfer of carbon from the atmosphere to the hydrosphere. Part of those dissolved HCO3-in the groundwater and surface water will degrade as CO_(2) and return to the atmosphere.
基金Under the auspices of the National Natural Science Foundation of China(No.41871182)the Open Fund of Key Laboratory of National Geographic Census and Monitoring,Ministry of Natural Resources(No.2022NGCM10)。
文摘Settlements and cultivated land are important production and living spaces in promoting rural revitalization.However,few studies have explored the relationship between rural settlements and cultivated land from spatiotemporal interaction perspective.This paper analyzed the spatiotemporal conversion and the interactive mechanism between rural settlements and cultivated land in a karst mountainous area(Qixingguan District of Guizhou Province)with fragile ecological environment in China during 2009–2018.The results showed that the expansion of rural settlements and the loss of cultivated land coexisted in Qixingguan District.Only 2.68%of the new cultivated land was reclaimed from rural settlements,whereas 85.45%of the new rural settlements occupied cultivated land.Six spatial expansion modes of rural settlements when occupying cultivated land were identified.Among these six modes,the area of the edge-expansion&along traffic roads(EA)mode accounted for 52.75%.The occupation by rural settlements made the cultivated land landscape more fragmented.The area ratio index of cultivated land to rural settlements(ARICR)of Qixingguan District averaged 18.75in 2009 and 17.21 in 2018,respectively.The ARICR reduced in all township administrative regions.Cultivated land with suitable slope condition for farming or without rocky desertification was more likely to be occupied by rural settlements.The probability of cultivated land occupied by rural settlements increased with the decrease of the distance to traffic roads,towns,and old rural settlements.The better the economic and social development of the township administrative regions,the more the ARICR decreased,while the richer the agricultural resources and the better the rural development of the township administrative regions,the less the ARICR decreased.The optimal reconstruction path of rural settlements,the comprehensive conservation path of cultivated land and the urban-rural integration development path in karst mountainous area were proposed.The findings would contribute to our understanding of the spatiotemporal interaction between rural settlements and cultivated land,and would provide a theoretical basis for promoting the coordinated development of rural man-land relationship and rural revitalization in karst areas.
文摘In recent years,karst construction projects in the built-up area of Wuhan(capital of Hubei Province,China)are increasing,and the karst geological disasters have aroused social concerns.The actual engineering projects usually use shallow geophysical exploration methods to explore karst.This paper uses Spatial Auto-Correlation Method(SPAC)and electromagnetic Computerized Tomography(CT)to detect karst in urban built-up areas.Depending on the different physical properties of rock and soil,the SPAC method can better reveal the interface between soil and rock strata and the interface between soil layers.The electromagnetic CT method can identify strata according to the apparent absorption coefficient,which can better reveal the interface between soil and rock,the interface between the more intact and weathered rock.The SPAC method is mainly qualitative to measure the low-speed area,namely,the wrong geological body i.e.,karst cave,but also can detect the fracture zone or filling mode of karst cave,and at the same time,cannot use exploration holes or logging observation.The electromagnetic CT method can accurately detect the location and scale of the karst caves and has a higher accuracy detecting karst bands.In addition,exploration holes or well logging observations are also expected to be conducted,and their detection effect is greatly affected by lithology.
基金funded by State Key Laboratory of Strata Intelligent Control and Green Mining Cofounded by Shandong Province and the Ministry of Science and Technology,Shandong University of Science and Technology(Grant No.MDPC2023ZR01)Open Fund of State Key Laboratory of Water Resource Protection and Utilization in Coal Mining(Grant No.WPUKFJJ2019-19)Major research project of Guizhou Provincial Department of Education on innovative groups(Grant No.Qianjiaohe KY[2019]070)。
文摘A comprehensive study was undertaken at Jiaozi coal mine to investigate the development regularity of ground fissures in shallow buried coal seam mining with Karst landform,shedding light on the development type,geographical distribution,dynamic development process,and failure mechanism of these ground fissures by employing field monitoring,numerical simulation,and theoretical analysis.The findings demonstrate that ground fissure development has an obvious feature of subregion,and its geographical distribution is significantly affected by topography.Tensile type,open type,and stepped type are three different categories of ground fissure.Ground fissures emerge dynamically as the panel advances,and they typically develop with a distance of less than periodic weighting step distance in advance of panel advancing position.Ground fissures present the dynamic development feature,temporary fissure has the ability of self-healing.The dynamic development process of ground fissure with closed-distance coal seam repeated mining is expounded,and the development scale is a dynamic development stage of“closure→expansion→stabilized”on the basis of the original development scale.From the perspective of topsoil deformation,the computation model considering two points movement vectors towards two directions of the gob and the ground surface is established,the development criterion considering the critical deformation value of topsoil is obtained.The mechanical model of hinged structure of inclined body is proposed to clarify the ground fissure development,and the interaction between slope activity and ground fissure development is expounded.These research results fulfill the gap of ground fissures about development regularity and formation mechanism,and can contribute to ground fissure prevention and treatment with Karst landform.
基金supported by the Guizhou Provincial Science and Technology Foundation(Qiankehe ZK[2022]-302)the National Natural Science Foundation of China,(Grant NO.41661088,41631179 and 42071316)+2 种基金the National Key Research and Development Program of China(Grant NO.2017YFB0503600)the Key Laboratory of Natural Resources Monitoring in Tropical and Subtropical Area of South China,Ministry of Natural Resources(No.2022NRM0004)Excellent Youth Project of Hunan Provincial Education Department(22B0725)。
文摘Mapping abandoned land is very important for accurate agricultural management.However,in karst mountainous areas,continuous high-resolution optical images are difficult to obtain in rainy weather,and the land is fragmented,which poses a great challenge for remote sensing monitoring of agriculture activities.In this study,a new method for identifying abandoned land is proposed:firstly,a few Google Earth images are used to transform arable land into accurate vectorized geo-parcels;secondly,a time-series data set was constructed using Sentinel-1A Alpha parameters for 2020 on each farmland geoparcel;thirdly,the semi-variation function(SVF)was used to analyze the spatial-temporal characteristics,then identify abandoned land.The results show:(1)On the basis of accurate spatial information and boundary of farmland land,the SAR time-series dataset reflects the structure and time-series response.abandoned land with an accuracy of 80.25%.The problem of remote sensing monitoring in rainy regions and complex surface areas is well-resolved.(2)The spatial heterogeneity of abandoned land is more obvious than that of cultivated land within geoparcels.The step size for significant changes in the SVF of abandoned land is shorter than that of cultivated land.(3)The SVF time sequence curve presented a strong peak feature when farmland was abandoned.This reveals that the internal spatial structure of abandoned land is more disordered and complex.It showed that time-series variations of spatial structure within cultivated land have broader applications in remote sensing monitoring of agriculture in complex imaging environments.
基金supported by the National Natural Science Foundation of China(42163003)the Project of Talent Base in Guizhou Province(No.RCJD2018-21).
文摘Carbon dioxide(CO_(2))emissions from aquatic ecosystems are an important component of the karst carbon cycle process and also a key indicator for assessing the effect of karst carbon sinks.This paper reviewed the CO_(2)partial pressure(pCO_(2))and its diffusion flux(FCO_(2))in karst surface aquatic ecosystems,mainly rivers,lakes,and reservoirs,and their influencing factors summarized the methods for monitoring CO_(2)emissions in karst aquatic ecosystems and discussed their adaptation conditions in karst areas.The pCO_(2)and FCO_(2)decreased in the order of rivers>reservoirs>lakes,and the values in karst lakes were eventually significantly lower than those in global lakes.The pCO_(2)and FCO_(2)of karst aquatic ecosystems had patterns of variation with diurnal,seasonal,water depth and hydrological cycles,and spatial and temporal hetero-geneity.The sources of CO_(2)in karst waters are influenced by both internal and external sources,and the key spatial and temporal factors affecting the CO_(2)emissions from karst rivers,lakes,and reservoirs were determined in terms of physicochemical indicators,biological factors,and bio-genic elements;additionally,the process of human activity interference on CO_(2)emissions was discussed.Finally,a conceptual model illustrating the impacts of urban devel-opment,agriculture,mining,and dam construction on the CO_(2)emissions at the karst surface aquatic ecosystem is presented.Meanwhile,based on the disadvantages existing in current research,we proposed several important research fields related to CO_(2)emissions from karst surface aquatic ecosystems.
文摘This experiment examined the fluctuations in nitrogen gas supersaturation throughout the day in three karst springs (upper, side, and lower) at McNenny State Fish Hatchery, rural Spearfish, Lawrence County, South Dakota, USA. Total gas pressures, oxygen percent saturation, and nitrogen percent saturation were recorded six times/day on eight days over a 26-day period in each of the three springs. Total gas pressure did not vary significantly throughout the day in any of the springs. However, percent oxygen and nitrogen saturation were significantly different throughout the day in all three springs. The highest mean (SE) nitrogen supersaturation value of 118.5 (1.1)% was observed in the lower spring at 07:00. The lowest mean nitrogen supersaturation values were 114.5 (1.1)% at 13:00 in the upper spring, and 114.2 (0.2)% and 113.1 (0.7)% at 15:00 in the side and lower spring, respectively. At 118% nitrogen supersaturation, gas bubble disease is likely to occur in fish, resulting in potentially high levels of mortality if untreated spring water was used for fish production. The results of this study indicate the importance of recording nitrogen gas levels at sunrise or early in the morning, when nitrogen is highest and oxygen is lowest, to obtain accurate and reproducible data.
文摘An analysis of the formation of karst and karst-suffosion forms on the territory of the West Kazakhstan region is presented in this paper. Numerous literary sources were used as the information database for the analysis of the relief features of the West Kazakhstan region. Evaluation of the morphometric features of the collapsed new formations on the basis of materials of our own field research is presented here for the first time. According to the research objectives there were defined localization places of the karst-collapsed phenomena where the reconnaissance field surveys were carried out. Survey points’ localization has been carried out by means of GPS system with the help of 12-channel GPS-receiver of Garmin eTrex model. Geoinformational technology, based on MapInfo 9.5 and ArcGIS 9.2 packages was used for the building of the information and cartographic database. Original thematic maps compiled on the basis of the research results’ analysis have been obtained in this research. The features of the Caspian Basin’s karst landscapes, formed as a result of salt-dome tectonic manifestations (Inder Mountains, Malaya Bogdo Mountain, Bish-Chokho hill) are described in this paper. The important elements of the Caspian Basin salt-dome landscapes are landforms of the karst origin from large karst depressions of the karst-tectonic origin to modern forms of the sulfate karst: sinkholes, wells, polje, knobs (“Kurgantau”), arches, caves and grottoes. Some karst formations have a non-salt-dome origin. Three areas with the collapsed forms that have the karst-suffosion origin have been identified (near Konyr village, Berezovka village and Zhanatalap village). The mechanism of the sinkholes formation is due to the changes of the groundwater regime and the displacement of limestone eluvium as a result of active anthropogenic impacts. The sinkholes occurence near Zhanatalap village, which is located near the Karachaganak oil and gas field, is probably due to the anthropogenic initiation of karst-suffosion processes.
文摘As highways are extended to deep mountains,high altitudes,and special geological conditions,tunnel construction becomes more and more challenging,especially the construction of tunnels in karst areas.Due to the particularity of the regional geological structure,karst is well developed in the southwest of our country,especially at areas where the problem of tunnel water inrush in karst areas is more prominent.To further ensure the safe construction and operation of tunnels,the characteristics of tunnels in karst areas is analyzed in this article.
文摘Water inrush,which is one of the challenging issues and hot topics in the tunneling industry,is very easy to occur during the construction of karst tunnels.The mechanism of water inrush of karst tunnels is discussed and analyzed in the paper:the water inrush of karst tunnels is generally divided into three steps,i.e.,the forming of the hazard source,the forming of the water inrush passage and the failure of the anti-inrush rock mass.The failure of the anti-inrush rock mass of karst tunnels are classified into 5 types,i.e.,the integral tensile-shear failure,the hydraulic fracturing,the infiltration induced sliding of the filling medium,the loss of key blocks and the comprehensive water inrush mode.The failure mechanism is studied on basis of typical cases and by means of numerical simulation or theoretical analysis.Conclusion is drawn that most of the water inrushes in actual tunneling are comprehensive water inrushes,which are the comprehensive results of the interrelation and interaction of various water inrush types,and that different types of water inrushes have related continuity and progressive evolution relationships under certain conditions.
