Karst Processes Research Articles

En

The study area is located at the intersection of a karstic plateau basin in the Munzur Mountain range and a low-lying karstic discharge area in the Ovacik Plain. The mountain range extends east to west and the glacial plain runs parallel in similar direction. The research area is an excellent microcosm of a polygenic morphological karst system. The mountain terrain visible today is dramatic barren landscape and the by-product of multiple, interrelated processes, such as glaciations, karstification and tectonics. The insurgence waters cut into the sediment, gain velocity, and then disappear into a seven meter high by seven meter wide swallow hole cave entrance at 2600m. In the past, pre-Pleistocene dolines had helped transform this area into an icefield landscape. When glaciation period ended, karstic process revived again during Holocene and Kepir Cave has operated as a swallow hole again. The main factors of change can be attributed to glaciations in Pleistocene and intensified karstification during the Holocene. The thick stacking limestone or massif provides the geologic structure for underground drainage and the formation of what may be a significant and deep cave system. The cave system appears to be developing vertically along a prominent fault that is visible just inside the swallow hole entrance. The resurgence, Elbaba, must be related to the Ovacik Fault extending at the northern edge of Ovacik Plain. This karstic system continues to develop as an active system fed by significant snow and rain waters.

Distinct lake level lowstand in Lake Prespa (SE Europe) at the time of the 74 (75) ka Toba eruption

Abstract. The 74 (75) ka Toba eruption in Sumatra, Indonesia, is considered to be one of the largest volcanic events during the Quaternary. Tephra from the Toba eruption has been found in many terrestrial and marine sedimentary deposits, and acidity peaks related to the eruption have been used to synchronize ice core records from Greenland and Antarctica. Seismic profiles and sedimentological data from Lake Prespa on the Balkan Peninsula, SE Europe, indicate a lake level lowstand at 73.6 ± 7.7 ka based on ESR dating of shells. Tephrostratigraphy, radiocarbon dating and tuning of the total organic carbon content with the NGRIP isotope record, corroborate that the lake level lowstand was a short-term event superimposed on the general cooling trend at the end of MIS 5, most likely at the onset of the Greenland Stadial GS-20. Acknowledging that tectonic events or karst processes could have triggered this lake level lowstand, the chronological correspondence between the lowstand and the Toba eruption is intriguing. Therefore a Toba-driven short-term shift to aridity in the Balkan region, leading to lake level changes and triggering spatial expansion events in one of the lake's most abundant benthic species, the carino mussel Dreissena presbensis, cannot be excluded.

Investigation into in situ stress fields in the asymmetric V-shaped river valley at the Wudongde dam site, southwest China

The Wudongde Reservoir, now being constructed on the lower reaches of the Jinsha River, will be the forth largest hydropower plant in terms of capacity in China. This project includes a concrete arch dam and two large-span underground caverns in both abutments. For their design and construction, in situ stress measurements and geological survey were conducted. In this study, following an introduction of the geological conditions and topography, an interpretation on the test results of in situ stresses is presented for clarifying the distribution features of natural stresses in the engineering area. It is interesting to find that the vertical stress is predominant in the project area and that the horizontal stress reduces largely in the relaxation zone near the bank slopes, while concentrates at the valley bottom and becomes normal in the depth of both abutments. Also analyzed are the effects of valley topography, geological conditions in the project area as well as the macro-regional tectonics on the distribution of in situ stresses at the dam site. A noteworthy finding is that topography and thickness of overburden are the main factors for the intermediate–low stress levels, that regional tectonics governs the stress orientation at the regional scale, and that river erosion, caprock structure and karstic processes have also contributed to the evolution of the valley and in situ stress state.

气象要素及土壤理化性质对不同土地利用方式下冬夏岩溶作用的影响

Many studies showed that the carbon sink resulted from karst process is fast and stable,which compose the very important part of "Missing carbon sink". Different land-use patterns can affect the karst process by influence the soilproperties. Commonly,with the land-use change from forest land to cultivated field the soil organic matter will reduce,the stability of soil structure get worse,the soil moisture retaining quality get down and the quantity of soil microbiology will diminish,all the above would affect the karst process. This study took 6 different land-use patterns( Tilled land( code: Ha),Paddy field( St),Reforested land( Tu), Abandoned Land( Hu),Mixed Woodland with Chinese fir-bamboo( Sz) and Bamboo land( Zh)) with the same geological backgrounds but different human influence intensity in Qingmuguan karst valley as a case study to determine the influence factors on karst processes. Standard limestone tablets were buried in the field to test the dissolution process rate. HOBO automatic weather station was located in the roof of local people's house to get the precipitation and temperature data. CO2 content in different soil layers were tested by Gas-Tec CO2tester. Soil samples in different layers were taken back to laboratory to detect the pH value,the organic matter,soil moisture content,and soil bulk density. The dissolution data from tablets showed that,firstly,the mean dissolution mass per unit area of different land-use patterns in different layers in Summer were 3.87 times than in Winter. The max mean dissolution mass changed from-80cm layer in Summer to-20—-50cm layers in Winter. Secondly,the mean dissolution mass in these two land-use patterns Ha and St with strong human influence intensity( Abbr. HII) was higher than that inTu and Hu in which the HII get weaker, while that in Sz and Zh which had the weakest HII with the lowest mean dissolution mass. Also,the range between them was higher in summer with strong HII than that in winter. Afteranalyzing the temperature( T),precipitation( P) and the soil physicochemical properties data,we can find that, there was a positive correlation between the change of dissolution mass with seasons and T,P which were the most important factors affecting the former. The soil CO2content can only play an important role on dissolution in summer which has more precipitation,and these two factors can react each other enough to form more carbonic acid so more carbonate tablets can be dissoluted. There was a negative correlation between soil organic matter and soil pH,and these two factors affected the dissolution jointly. They can influence dissolution greatest only in surface layer with high organic matter and low pH,while less in deeper layers. The influence of soil texture determined by soil bulk density and soil porosity on dissolution was bidirectional. The clay with good moisture retaining quality but bad permeability was benefit for the dissolution in winter for there was less precipitation that time,but bad in summer for there was no so much water pass through the soil,Hu was a good example of this. However,there was an oppose process in sandy soil with good permeability but bad moisture retaining quality,corresponded more dissolution in summer and less in winter,there was a good example of tilled land also. Additionally,the use of farmyard manure and chemical fertilizer which include NO-3and SO2-4can promote the dissolution process too. Above all,the results of this study can provide consultation for evaluate karst carbon sink more scientifically and accurately.

Quaternary glacial cycles: Karst processes and the global CO2 budget

Extensive research has been conducted investigating the relationship between karst processes, carbonate deposition and the global carbon cycle. However, little work has been done looking into the relationship between glaciations, subsequent sea level changes, and aerially exposed land masses in relation to karstic processes and the global carbon budget. During glaciations sea-level exposed the world’s carbonate platforms. With the sub-aerial exposure of the platforms, karst processes can occur, and the dissolution of carbonate material can commence, resulting in the drawdown of CO2 from the atmosphere as HCO3−. Furthermore, the material on the platform surfaces is primarily aragonite which is more readily soluble than calcite allowing karst processes to occur more quickly. During glaciations arctic carbonates and some of the temperate carbonates are blanketed in ice, effectively removing those areas from karst processes. Given the higher solubility of aragonite, and the extent of carbonate platforms exposed during glaciations, this dissolution balances the CO2 no longer taken up by karst processes at higher latitudes that were covered during the last glacial maximum The balance is within 0.001 GtC / yr, using soil pCO2 (0.005 GtC/yr assuming atmospheric pCO2) which is a difference of <1% of the total amount of atmospheric CO2 removed in a year by karst processes. Denudation was calculated using the maximum potential dissolution formulas of Gombert (2002). On a year to year basis the net amount of atmospheric carbon removed through karstic processes is equivalent between the last glacial maximum and the present day, however, the earth has spent more time in a glacial configuration during the Quaternary, which suggests that there is a net drawdown of atmospheric carbon during glaciations from karst processes, which may serve as a feedback to prolong glacial episodes. This research has significance for understanding the global carbon budget during the Quaternary. Keywords: Karst, Global Carbon Budget, Quaternary, Last Glacial Maximum, Carbonate Dissolution. DOI: 10.3986/ac.v42i2-3.661

Formation, distribution and potential of deep hydrocarbon resources in China

Abstract The onshore exploration realm has been continuously expanded to (ultra-) deep oil and gas recently in China. New comprehension and significant breakthroughs have been made in understanding generation and preservation conditions, reservoirs formation mechanisms, exploration potential, petroleum resources assessments, and exploration engineering technology of deep oil and gas. Deep oil and gas reservoirs include clastic, carbonate and volcanic settings. The temperature of deep oil can be up to 295 °C. Long term shallow burial and rapid deep burial at late stages help preserve the porosity in deep clastic rocks, and dissolution and fracturing effects improve their reservoir properties. Affected by faulting, hydrothermal karst processes, dolomitization and early oil and gas injection, carbonate rocks have good reservoir properties even at depths of 8 000 m. Controlled by tectonism, volcanism, diagenesis and diagenetic reconstruction during supergene and burial stages, primary and secondary weathering types of reservoirs develop deep volcanic reservoirs. Deep oil and gas resources in China are distributed mainly within three main practical areas of carbonate, clastic and volcanic areas. Dominated by gas, some of the more productive areas include the Tarim, Ordos, Sichuan, Junggar, Songliao, Santanghu and Bohai Bay basins. Deep oil and gas exploration in China has entered an age of breakthrough and discovery. Relevant engineering technology, such as ultra deep well drilling and ultra high temperature drilling fluid techniques have facilitated the ability to find (ultra-) deep oil and gas.

Seismic Surface-wave Prospecting Methods for Sinkhole Hazard Assessment along the Dead Sea Shoreline

The Dead Sea (DS) coastal areas have been dramatically hit by sinkhole occurrences since around 1990. It has been shown that the sinkholes along both Israeli and Jordanian shorelines are linked to evaporate karst cavities that are formed by slow salt dissolution. Both the timing and location of sinkholes suggest that: 1) the salt weakens as the result of unsaturated water circulation, thus enhancing the karstification process; and 2) sinkholes appear to be related to the decompaction of the sediments above karstified zones. The location, depth, thickness and weakening of salt layers along the DS shorelines, as well as the thickness and mechanical properties of the upper sedimentary deposits, are thus considered as controlling factors of this on-going process. The knowledge of shear-wave velocities (Vs) should add valuable insights on mechanical properties of both the salt and its overburden. We have suggested Vs estimation using surface-wave prospecting methods, based on surface-wave dispersion measurements and inversion. Two approaches have been used. Along the Israeli shoreline, Vs mapping has been performed to discriminate weak and hard zones within salt layers, after calibration of inverted Vs near boreholes. It has been shown that there is a Vs increase in the DS direction. Initially examined weak zones, located near the salt edge, associated with karstified salt, are characterized by Vs values of 760–1,050 m/s, and extend 60–100 m from the salt edge in the DS direction. Hard salt zones with velocity Vs values greater than 1,500 m/s are located at distances of more than 100–220 m from the salt edge. Finally, transition zones (1,050 &lt; Vs &lt; 1,500 m/s) have a 40–160 m spread. On a Jordanian site, roll-along acquisition and dispersion stacking has been performed to achieve multi-modal dispersion measurements along linear profiles. Inverted pseudo-2-D Vs sections present low Vs anomalies in the vicinity of existing sinkholes and made it possible to detect decompacted sediments associated with potential sinkhole occurrences. Moreover, Vs profiles showed a high velocity unit at 40–50 m depth that can be interpreted as a salt layer.

Geomorphological map of the central sector of the Matese Mountains (Southern Italy): an example of complex landscape evolution in a Mediterranean mountain environment

A 1:28,000 scale geomorphological map of the central sector of the Matese Mountains (Southern Italy) is presented in this paper. Geomorphological investigation by means of remote sensing, cartographic analysis and field surveys allowed the identification of the main geomorphic processes and to map the related landforms which are both of monogenetic and polygenetic origin. Most of them are erosional landforms generated by the action of periglacial, glacial and karst processes which often occur under the control of the geological structure. Glacial relics and polygenetic landforms of glaciokarst and fluviokarst origin provide good evidence of the strong influence of variable climatic conditions on landform genesis during the Quaternary. They also highlight the influence of extensive tectonics during the Quaternary which caused progressive uplift, fragmentation and disarticulation of the developing mountainous landscape and its consequent polycyclic evolution. The map illustrates the geomorphologic peculiarities of the Mediterranean mountain landscape that typically characterizes the Apennine chain, and contributes to the understanding of its tectonic evolution and the influence of climate and climatic changes on landscape evolution. It further provides a basic map for land planning policy including the exploitation of the geological heritage and the development of sustainable mountain tourism and geo-tourism.

Variability of groundwater flow and transport processes in karst under different hydrologic conditions

Significance of hydrological variability in karst is presented, which also discusses factors inducing such variability and consequences it may cause. Groundwater flow in karst aquifers is often characterized by strong variability of flow dynamics in response to different hydrologic conditions within a short time period. Consequently, water table fluctuations are often in the order of tens of meters, differences in flow velocities between low- and high-flow conditions can reach ten or even more times. In dependence to respective hydrologic conditions groundwater flow also results in variations of flow directions, and thus in contribution of different parts of the aquifer to a particular spring. The described hydrological variability has many implications for contaminant transport, groundwater availability and vulnerability. Groundwater level rising reduces thickness of the unsaturated zone and decreases protectiveness of the overlying layers. Higher water flow velocities reduce underground retention. Due to more turbulent flow, transport and remobilization of solute and insoluble matter is more effective. During high-flow conditions there is usually more surface flow and hence more concentrated infiltration underground. Particularly in karst systems that show very high hydrologic variability, this should be considered to correctly characterize, understand or predict the aquifers’ hydrological behaviour and to prepare proper protection strategies.Keywords: karst aquifer, temporal hydrological variability, groundwater flow, transport processes, karst spring, water source protection.DOI: 10.3986/ac.v42i2.644

Using non-conservative tracers to characterise karstification processes in the Merinos-Colorado-Carrasco carbonate aquifer system (southern Spain)

The systematic sampling of the chemical composition of the groundwater from five karst springs (including an overflow spring) and one outflowing borehole have permitted to determine distinctive chemical changes in the waters that reflect the geochemical processes occurring in a carbonate aquifer system from southern Spain. The analysis of the dissolution parameters revealed that geochemical evolution of the karst waters basically depends on the availability of the minerals forming aquifer rocks and the residence time within the aquifers. In the three proposed scenarios in the aquifers, which include the preferential flow routines, the more important geochemical processes taking place during the groundwater flow from the recharge to the discharge zones are: CO2 dissolution and exsolution (outgassing), calcite net dissolution, calcite and dolomite sequential dissolution, gypsum/anhydrite and halite dissolution, de-dolomitization and calcite precipita- tion. A detailed analysis of the hydrochemical data set, saturation indices of the minerals and partial pressure of CO2 in the waters joined to the application of geochemical modelling methods allowed the elaboration of a hydro- geochemical model of the studied aquifers. The developed approach contributes to a better understanding of the karstification processes and the hydrogeological functioning of carbonate aquifers, the latter being a crucial aspect for the suitable management of the water resources.

Multi-proxy evidence for human-induced deforestation and cultivation from a late Holocene stalagmite from middle Java, Indonesia

Speleothem multi-proxy records have proved highly useful in reconstructing past changes in climatic and environmental conditions as well as karst processes, and in distinguishing between the numerous potential driving forces that influence these proxies. There is lack of such terrestrial proxies from the tropical Indo-Pacific. For the first time, we present an annual- to decadal-scale multi-proxy record of 377 samples including stable isotopes (δ18O, δ13C) and trace elements (Mg/Ca, Sr/Ca) from a Holocene calcite stalagmite from Bribin Cave, Gunung Kidul regency, middle Java, Indonesia that has grown over the last 4000years (11 230Th dates). δ18O values average −7‰ with high-frequency variability of up to 1‰, and hint at relatively stable overall climatic conditions in the tropical Indo-Pacific region during the late Holocene. The δ13C values of stalagmite JB2 are low (~−13‰) at the beginning of the record suggesting a C3-dominated rainforest cover. Strong positive covariation with Mg/Ca and Sr/Ca ratios is a stringent indication of a dominant natural control by prior calcite precipitation and water–rock interaction. However, δ13C values increase dramatically by ~4‰ from ~1.1ka to ~0.5ka, clear evidence of an anthropogenic influence through deforestation and cultivation.

The Soil and Vegetation Effect on Carbon Transfer Path in Epigenic Karst System

It was proved that karst processing during groundwater cycle is one of carbon sinks to the atmosphere CO2. To understand the carbon transfer path among the three phases of air, carbonate rocks and karst groundwater in epigenic karst system is very important for mechanic studies of karst carbon sink. There are 8 carbon stable isotope sample sites, including 5 groundwater sites and 3 gaseous CO2 sites in Banzhai river catchment. The total 41 samples, including 38 karst water samples and 3 CO2 samples are acquired in a whole hydrological year of 2010. 4 couples CO2 partial pressure including free air and soil air are tested in site. Based on analysis the carbon stable isotope and CO2 partial pressure data above, it is found that the mostly carbon in free air and karst water is from soil air. The carbon transfer path in epigenic karst system can be divided into 4 steps: 1 the photosynthesis of vegetation take CO2 from free air; 2 the respiration of plant roots and decomposition of humic substance release CO2 to soil layer; 3 the gaseous CO2 is transfer to liquid HCO3- negion by karst process during the water cycle; 4 the bicarbonate in groundwater move to river or ocean fellow the groundwater flow. The forest and soil takes a booster pump action increasing the CO2 partial pressure from free air to soil and it is very important in karst process.

Bucket structure in carbonate accumulations of the Maldive, Chagos and Laccadive archipelagos

Peritidal platforms rimmed by reefs, and raised reefs rimming deep lagoons, are characteristic morphologies of the tropical carbonate factory; their geometry contrasts sharply with the seaward-sloping shelves of siliciclastic margins. The structure has been compared to a bucket—stiff reef rims holding a pile of loose sediment. Remote-sensing data from the Maldive, Chagos and Laccadive archipelagos of the Indian Ocean show that ring reefs with bucket structure are the dominant depositional pattern from patch reefs of tens of meters to archipelagos of hundreds of kilometers in diameter, that is, over more than 4 orders of magnitude in linear size. Over 2.5 orders of magnitude, the bucket structures qualify as statistical fractals, exhibiting self-similar patterns and size distributions following power laws. However, most regional or genetic subsets of the data follow lognormal distributions and small subsets of lagoon reefs exhibit exponential distributions. Seismic data and boreholes in the Maldives indicate that the bucket has been a dominant depositional motif since the Oligocene. Ecological and hydrodynamic studies on modern reefs suggest that the bucket structure is a form of biotic self-organization: the edge position in a reef is favored over the center position because bottom shear is higher and the diffusive boundary layer between reef and water thinner. Thus, the reef edge has easier access to nutrients and is less likely to be buried by sediment. The bucket structure reflects these conditions. Karst processes have accentuated the surface relief of the buckets, particularly in the late Quaternary.

Results of persistent scatterer interferometry of the new planned Visaginas Nuclear Power Plant area, Lithuania

Ground surface deformations can be related to tectonic motions, landsliding, flooding, erosion, groundwater pumping, karst processes, etc. Ground movement data can be obtained from stationary observations using standard geodetic methods, GPS as well as using geostationary satellites. The combination of the methods and additional geological information can improve the understanding of the processes and clarify the causes of the ground surface movements. In Lithuania, the ground surface deformations are usually related to landsliding, karst, suffusion, technogenic processes, which can trigger deformations of foundations, destruction of buildings, and other harmful accidents. Lithuania is planning to build a new Nuclear Power Plant (NPP), therefore the assessment of the stability of the ground (and structures upon it) across potential new NPP construction sites and their vicinity is a question of vital importance. IAEA SSG-9 safety guidelines recommend remote sensing imagery to be employed to better understand ongoing rates and the type of tectonic activity, therefore the rate of ground surface movements is the vital information for planning and designing a new NPP. The Persistent Scatterer Interferometry (PSI) data has been used to provide historical motion measurements across the new planned Visaginas NPP area. The aim of this paper is to present the PSI dataset interpretation results and clarify the causes of the ground surface vertical movements in the studied Visaginas area.

Advanced modelling of runoff and soil redistribution for agricultural systems: The SERT model

Hydrological and soil erosion models allow mapping and quantifying rates of runoff depths and soil redistribution for different land uses and climatic scenarios. Mediterranean soils are threatened by marked seasonal changes in the climatic, thus soil and vegetation parameters and modelling predictions at monthly scale are required. The semi-physically-based Soil Erosion and Redistribution Tool (SERT) model is presented together with the results of its application in a Mediterranean agro-ecosystem (NE Spain) with a detailed database. The hydrological module is based on the recently published DR2 (Distributed Rainfall-Runoff) water balance model and the effects of man-made infrastructures on the natural dynamics of runoff connectivity are added. The erosion module is built using, as the basis, the Revised Morgan, Morgan and Finney model, and the new Remaining runoff Transport Capacity (TCr) factor used to estimate the rates of soil loss and deposition. Predicted runoff depth varied in time and space, presenting areas without runoff production mainly in Rendzic Leptosols and Haplic Calcisols between November and April. Average soil erosion was high in cultivated and bare soils, ca. 20 and 10Mgha−1yr−1, whereas rangeland soils were affected by moderate and, in some areas, by limited erosion processes. Soil erosion was minimal in February (0.08Mgha−1month−1 on average) and 23 times higher in October. The SERT model allowed mapping the significant changes in the monthly values of soil redistribution quantifying the variability in the magnitude of the processes involved. Predicted values of average soil loss and deposition were validated against quantified values with 137Cs obtaining an average Nash–Sutcliffe efficiency of 0.48 (Pearson's r=0.709) and a sediment balance of −1.15Mgyr−1 for the whole catchment that is consistent with the karst processes of the study area. The new model is an easy-to-run, reliable, low-input-demanding management tool with valuable outputs for hydrological and soil erosion studies in small agricultural catchments.

Long-Term Geological Challenges of Dam Construction in a Carbonate Terrane

Many carbonate foundations of dams are afflicted with zones of broken or fractured rock and karstification prior to construction. Rock fractures develop because of tectonic stresses but also because of the removal of overburden loads imposed upon the rock. This is the case with valley stress relief. As fractures control many of earth9s dynamic processes, including fluid transport in the crust, an understanding of valley stress relief is essential for an understanding of karstification. Because water impounded by a structure imposes an increased hydraulic gradient, and because this gradient facilitates the solubility of that carbonate foundation, fractures or bedding planes undergo accelerated transformation by the karstification process and enhance additional dynamics affecting the dissolution rate of carbonates. In a state of nature, karstification requires a time scale of 10,000 to more than 100,000 years. However, when subject to the imposed-increased hydraulic gradients associated with impoundment, the rate of karstification may accelerate a thousand-fold. Civil engineers and geologists have noted that grout curtains or concrete cut-off walls, structures typically used to deal with this problem, offer mixed success in terms of extending the design life of a water retention structure. Traditional repairs impose a new hydraulic gradient causing increased infiltration of the minute, non-groutable, clay-filled microfractures. Construction is an incremental process. The imposed hydraulic gradient increases incrementally as ungrouted microfractures become susceptible to karstification, accelerating development of new seepage channels. Eventually, seepage becomes intolerable as karstification renders the impoundment susceptible to another round of repairs. Four case histories illustrate these concepts.

Analysis of human induced changes in a karst landscape — the filling of dolines in the Kras plateau, Slovenia

A comprehensive analysis of the increased pressure on karst landscapes due to expansive economic and urban development is presented with the aim of evaluating changes in land use and their deleterious effects on karst relief forms. The study focuses on two areas surrounding the relatively quickly growing settlements of Hrpelje-Kozina and Divača on the Kras plateau (Slovenia) that have been subjected to intensive urban and business development and traffic since the motorway was brought to their vicinity fifteen years ago. National legislation loopholes and technological improvement were the cause of the commonly unsupervised human encroachment which caused the widespread degradation of the landscape. By comparing different topographical and ortophotographical materials from the past four decades and by detailed field inspection of land use and environmental changes, as well as the morphometrical characterization of dolines, the following results have been found: due to the population growth in the past four decades (39% and 50%, respectively), an increase of settlement area by 18 and 11 percentage points took place. Consequently, between 25 and 27% of dolines have disappeared or have been extensively modified (filled up and leveled). According to the local spatial plans, an additional 18% to 28% dolines are endangered. Broad human induced changes in the karst landscape have resulted in a noticeable increase in landscape deterioration, which is consistent with similar phenomena observed in other regions. Due to the extreme susceptibility of the karst to human activities that may lead to the degradation of its exceptional esthetic and environmental value, the alteration of karst processes such as corrosion, endangering of unique habitats and the quality of non-renewable natural resources, it is necessary to promptly define measures for its protection at the national level.

不同土地利用方式土下岩溶溶蚀速率及影响因素

The unique karst ecosystem of Southwest China is an example of a typical vulnerable ecosystem and key eco-region in China.Rocky and soil desertification in the karst environment are two of the most serious problems,and unsuitable land use patterns will intensify the desertification.Increasing attention has been paid to the impact of land-use types on karst processes and consequently to investigate the best way to restore the ecosystem in rock and soil desertification areas,it is necessary to study the influences of changes in the soil environment on karst processes under different land use patterns.Soil physical and chemical variations result from land cover,and the resulting special karst micro-environments could intensively affect karst processes under different land use patterns. A case study was conducted at Mt.Zhongliang,Chongqing,in order to analyze and investigate the dissolution rate in a karst area and the factors which influence it under different land use patterns.Standard limestone tablets were buried in the field,soil CO2 collection devices were set up,and tracer experiments using a bright blue dye were carried out.The dissolution rate of carbonate rocks,soil CO2 concentrations,and dissolved organic carbon(DOC) contents were measured in different soil layers at depths of 20 cm and 50 cm,as well as land use patterns and soil properties,such as moisture,porosity and pH. The average contents of soil DOC from the highest to lowest were in the order: woodlandgrasslandvegetable land.There was a significant difference in soil DOC content in the upper soil horizon(0—20 cm) between woodland and vegetable land,as well as in the lower horizon(20—50 cm) among woodland,vegetable land and grassland.The diversity of soil water content and porosity indicates that woodland and grassland are beneficial for maintaining water content.Use of the dye indicated an obvious distribution of soil preferential flow in woodland and grassland,but not in the vegetable land.Soil CO2 concentrations and pH values at 50 cm depth were higher than at 20 cm,and were present in the order: grasslandwoodlandvegetable land.Woodland and grassland have greater vegetation coverage,more plant residues,and greater microbial activity,which may be the reason for the variations in soil physical and chemical properties under the different land use patterns. The study showed that soil physical and chemical properties were affected by different land use patterns,forming special karst micro-environments and resulting in different karst processes in different soil layers.Dissolution rates in the dry season were in the order: grasslandvegetable landwoodland.Soil CO2 concentration is an important driving force affecting the dissolution rate in woodland and grassland during the dry season;soil moisture and water-supplying capacity are key factors influencing the dissolution rate under the different land use patterns in the dry season;the average dissolution rate in the vegetable land is higher than that in the woodland as more acid materials are produced in the vegetable land which has the lowest pH;the DOC of soil has a strong transforming ability with water infiltration,which is one of the reasons why the dissolution rate of forest land 50 cm beneath the soil is higher than that at 20cm.This research provides a theoretical basis and data reference for the mechanism of karst dissolution and the karst carbon sink in southwestern China.

Kurucaova Polyesinin Jeomorfolojisi (Kırıkhan/Hatay)

Kurucaova Polje, Middle Amanus Mountains is located in the control of a fault developing paleovalley tectono-karstic depression that formed as a result of karst processes. Other than in the presence of carbonate rocks that are effective in the development process to another, provided that the water contact with the ground for a long time paleovalley structure, has been the most important factor induces the formation of polje. Faulting accompanied by other factors that are effective in the formation of the developing polje karstification. Explanation of geomorphological features and the development of study was to Kurucaova Polje. Thus, important evidence about the formation and development of this region detected in the geological past. During the study, both as a priority issue, both in terms of the relevant literature is reviewed. The findings were compared with detailed maps of topography and geology. The maps on the Geographic Information Systems (GIS) analyzes were conducted on a variety of methods and techniques using and working maps. In this study, the main base map sheet with 1:25.000 scale topographic ANTAKYA-O36c4 geological maps of different scales are used. In addition, Remote Sensing (RS) satellite imagery in a variety of recent methodology used. Accompanied by field studies in all these activities have been audited and tested for accuracy on-site interviews and observation methods. Finally, since the Middle Miocene Kurucaova Polje Neotectonic movements and karstification processes that operates within the framework of a joint association formed and Plio-Quaternary phase reaches the top of this formation process is understood. Some applications must be made at certain stages in terms of current use polje. At this point, start to operate in a planned way to the mine opened, polje field of agricultural or livestock purposes (could be either way), and some are designed for nature enthusiasts of polje with the use of the natural values for the purpose of ecotourism-related activities or the completion of jeomorfoturizm should be provided.

岩溶山区水分时空异质性及植物适应机理研究进展

PDF HTML阅读 XML下载 导出引用 引用提醒 岩溶山区水分时空异质性及植物适应机理研究进展 DOI: 10.5846/stxb201112011836 作者: 作者单位: 中国科学院亚热带农业生态研究所 亚热带农业生态过程重点实验室,中国科学院亚热带农业生态研究所 亚热带农业生态过程重点实验室,中国科学院亚热带农业生态研究所 亚热带农业生态过程重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院西部行动计划项目(KZCX2-XB3-10); 国家自然科学基金项目(41171187,31100294); 国家科技支撑计划课题(2010BAE00739-02) Spatio-temporal heterogeneity of water and plant adaptation mechanisms in karst regions: a review Author: Affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences,Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences,Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:西南岩溶地区虽然降水充沛,但因具有二元水文结构,地表水大量渗漏、地下水深埋,加上土层浅薄且分布不连续、土壤储水能力低,岩溶干旱严重,水分亏缺仍然是植被恢复重建的关键限制因子。如何有效地进行植被的恢复重建和实现水土资源的协调利用,是该地区石漠化综合治理面临的主要难题。由于地质背景的特殊性、地形地貌的复杂性和生境的高度异质性,岩溶山区水分运移过程与其他类型区显著不同,亟需综合考虑岩性、地形地貌、土壤与岩石分布、植被等因素的影响。在简要介绍岩溶山区土壤-岩石环境特征的基础上,综述了降雨入渗产流规律、水分时空异质性、植物水分来源及适应机理等几个方面的研究进展,探讨了当前研究中存在的问题,并对未来研究进行了展望。今后应以大气-植被-土壤-岩石系统为研究对象,将水分运移过程与植物的水分利用方式有机结合,综合运用土壤物理学、生态水文学、植物生理学、岩溶地质学等多学科研究手段,探讨表层岩溶带的水文调节功能及其主要影响因素,揭示坡面、小流域尺度植被与水文过程的相互作用机理,为西南岩溶山区水源涵养型植物群落的优化配置提供科学依据。 Abstract:Karst ecosystem is very fragile and sensitive to environmental change. China has the largest karst area (344.3×104 km2) with the widest distribution and highest landform diversity in the world, mainly or primarily concentrating in the southwest (about 55×104 km2). The karst region of southwest China is geology-controlled eco-environment, and the basic characteristics include the shortage of surface water and soil resources, low vegetation coverage and high diversity of microhabitats. Due to special geological background, intensive karst process and recent irrational land uses, both vegetation destruction and soil and water loss are increasingly serious in karst region of southwest China. This results in karst desertification, a process of land degradation involving extensive exposure of basement rocks and drastic decrease in soil productivity. Karst desertification has been leading to the concentrated poverty population and the lack of cultivated land. The karst region of southwest China, the crucial area for the West Development in China, is easy to plunge into a vicious circle between poverty and environmental degradation. Therefore, how to rehabilitate vegetation effectively and to utilize soil and water resources harmoniously are the primary problems for the comprehensive control of karst desertification in this region. Although rainfall is abundant, surface water is leaked heavily and groundwater is buried deeply due to dual hydrological structure in karst region of southwest China. Karst drought is serious and water deficit is still the primary factor for influencing vegetation restoration due to discontinuous shallow soils and low soil storage capacity. Thus, study on spatio-temporal heterogeneity of water and plant adaptation mechanisms is very important for vegetation restoration in karst region of southwest China. Water movement in karst region is significantly different from other kinds of region because of special geological background, complex landform and high heterogeneous habitat, and the effects of lithology, topography, the soil-rock distribution and vegetation should be considered altogether. Although many advances have been achieved on hillslope rainfall infiltration and runoff generation, spatial variability of soil water, adaptation of plants to water stress in different habitats, the current researches can not illustrate the difference of water status in various soil-rock environments and the corresponding adaptation mechanisms in karst regions. This heavily affects the achievement of vegetation restoration and reconstruction. In this paper, on the basis of the simple introduction to the characteristics of soil-rock environment, the research advances on rainfall infiltration and runoff generation, spatio-temporal variability of soil water, plant water sources and its adaptation mechanisms were summarized in karst regions. The further study should attach importance to investigate the relationship between water movement in soils and fractured rocks and plant water utilization, and to survey the effects of various environmental factors on eco-hydrological processes in the atmosphere-plant-soil-rock system. In order to reveal the interactive mechanism of vegetation and hydrological processes at hilllsope and catchment scales in karst areas, the multi-disciplinary research methods and techniques, including soil physics, eco-hydrology, plant physiology and karstology, should be applied to discuss the hydrological regulation function of epikarst and its primary influencing factors. These studies would provide scientific basis for optimal disposition of plant community with water-conserving function in karst region of southwest China. 参考文献 相似文献 引证文献