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1.
Kenneth S. Johnson 《Environmental Geology》2005,48(3):395-409
Evaporites, including gypsum (or anhydrite) and salt, are the most soluble of common rocks; they are dissolved readily to form the same type of karst features that typically are found in limestones and dolomites, and their dissolution can locally result in major subsidence structures. The four basic requirements for evaporite dissolution to occur are: (1) a deposit of gypsum or salt; (2) water, unsaturated with CaSO4 or NaCl; (3) an outlet for escape of dissolving water; and (4) energy to cause water to flow through the system. Evaporites are present in 32 of the 48 contiguous states of the United States, and they underlie about 35–40% of the land area. Karst is known at least locally (and sometimes quite extensively) in almost all areas underlain by evaporites, and some of these karst features involve significant subsidence. The most widespread and pronounced examples of both gypsum and salt karst and subsidence are in the Permian basin of the southwestern United States, but many other areas also are significant. Human activities have caused some evaporite–subsidence development, primarily in salt deposits. Boreholes may enable (either intentionally or inadvertently) unsaturated water to flow through or against salt deposits, thus allowing development of small to large dissolution cavities. If the dissolution cavity is large enough and shallow enough, successive roof failures above the cavity can cause land subsidence or catastrophic collapse. 相似文献
2.
3.
Kenneth S. Johnson 《Environmental Geology》2008,53(5):945-950
Gypsum is a highly soluble rock and is dissolved readily to form caves, sinkholes, disappearing streams, and other karst features
that typically are also present in limestones and dolomites. Gypsum karst is widespread in the USA and has caused problems
at several sites where dams were built, or where dam construction was considered. Gypsum karst is present (at least locally)
in most areas where gypsum crops out, or is less than 30–60 m below the land surface. These karst features can compromise
on the ability of a dam to hold water in a reservoir, and can even cause collapse of a dam. Gypsum karst in the abutments
or foundation of a dam can allow water to pass through, around, or under a dam, and solution channels can enlarge quickly,
once water starts flowing through such a karst system. The common procedure for controlling gypsum karst beneath the dam is
a deep cut-off trench, backfilled with impermeable material, or a close-spaced grout curtain that hopefully will fill all
cavities. In Oklahoma, the proposed Upper Mangum Dam was abandoned before construction, because of extensive gypsum karst
in the abutments and impoundment area. Catastrophic failure of the Quail Creek Dike in southwest Utah in 1989 was due to flow
of water through an undetected karstified gypsum unit beneath the earth-fill embankment. The dike was rebuilt, at a cost of
US $12 million, with construction of a cut-off trench 600 m long and 25 m deep. Other dams in the USA with severe gypsum-karst
leakage problems in recent years are Horsetooth and Carter Lake Dams, in Colorado, and Anchor Dam, in Wyoming. 相似文献
4.
太原盆地是新生代断陷盆地, 盆地内受南北和东西多组断层控制形成了多个断垒、断块, 岩溶热矿水主要分布在三给地垒以南和田庄断裂以北的区域。岩溶热矿水的主力产水层为奥陶系的峰峰组和上、下马家沟组的碳酸盐岩储层。项目组采集了18个地热水样品, 同时收集了已有文献中的9个地热水和3个地下冷水的水化学数据。根据分析化验结果, 岩溶热矿水的水化学类型为SO4-Ca ·Mg型。根据热矿水中的离子浓度关系和主要矿物的饱和度指数可以推断水化学类型主要受石膏层的影响。地下水溶滤过程中除了方解石与白云石溶解作用外, 石膏的溶解作用占主导地位。根据矿物饱和度指数, 石膏溶解产生过多Ca2+以及热矿水温度的升高还导致了方解石或者白云石更加饱和, 可能发生沉淀。西温庄隆起内的岩溶热矿水混合了古水, 年龄均大于20 000 a, 岩溶热储温度为72.6~91.1 ℃, 循环深度为2123~2663 m。长时间的水岩相互作用, 为热矿水的形成提供传导加热的时间和丰富的矿物质组分。西温庄隆起作为岩溶热矿水温度、TDS以及锶浓度的高值区, 是盆地内热矿水的汇水区, 同时也是区域热矿水条件最好的区域。TDS和Sr浓度升高趋势反映了地下水从补给区到盆地内排泄区明显的溶滤作用, 并且发生了由低TDS的HCO3-Ca ·Mg型地下冷水往高TDS的SO4-Ca ·Mg型岩溶热矿水的发展。 相似文献
5.
《Environmental Earth Sciences》2012,65(3):805-812
Karst topography is a landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually limestone and evaporites.
Karstification in the Sivas basin (Turkey) has sculpted a beautiful landscape with a distinctive beauty and appeal for both
local inhabitants and visitors. Dolines are very special geological landscape features found in karst regions, and the Sivas
basin has several giant dolines amongst its thousands of smaller dolines. The basin constitutes a distinctive karst architecture
with a system of collapse and/or dolines and caves. Anyone who walks along the shores of a lake resulting from the collapse,
in this gypsum terrain, will be amazed with the lake and rocks that surround them. In this paper, dolines in the gypsum terrain
are evaluated and discussed according to their value as a “Geological Heritage”. Three main characteristics of dolines, namely
their scientific, aesthetic and ecosystem importance are considered and discussed. Dolines and karstified areas as representative
examples of landform types possess the three attributes for them to be considered as a Geological Heritage in that they demonstrate
the effect of erosion on the landform, geomorphic processes that are still active and a range of features characteristic of
the rock unit involved. 相似文献
6.
Geochemical evolution of groundwater in carbonate aquifers in Taiyuan, northern China 总被引：4，自引：0，他引：4
Rui Ma Yanxin WangZiyong Sun Chunmiao ZhengTeng Ma Henning Prommer 《Applied Geochemistry》2011,26(5):884-897
Thirty-nine samples of both cold and thermal karst groundwater from Taiyuan, northern China were collected and analyzed with the aim of developing a better understanding of the geochemical processes that control the groundwater quality evolution in the region’s carbonate aquifers. The region’s karst groundwater system was divided into three geologically distinct sub-systems, namely, the Xishan Mountain karst groundwater subsystem (XMK), the Dongshan Mountain karst groundwater subsystem (DMK) and the Beishan Mountain karst groundwater subsystem (BMK). Hydrochemical properties of the karst groundwaters evolve from the recharge zones towards the cold water discharge zones and further towards the thermal water discharge zones. In the XMK and the DMK, the hydrochemical type of the groundwater evolves from HCO3-Ca·Mg in the recharge - flow-through zone, to HCO3·SO4-Ca·Mg/SO4·HCO3-Ca·Mg in the cold water discharge zone, and further to SO4-Ca·Mg in the thermal water discharge zone. By contrast, the water type changes from HCO3-Ca·Mg to HCO3·SO4-Ca·Mg in the BMK, with almost invariable TDS and temperatures all along from the recharge to the discharge zone. The concentrations of Sr, Si, Fe, F− and of some trace elements (Al, B, Li, Mn, Mo, Co, Ni) increase as groundwater temperature increases. Different hydrogeochemical processes occur in the three karst groundwater sub-systems. In the XMK and the DMK, the geochemical evolution of the groundwater is jointly controlled by carbonate dissolution/precipitation, gypsum dissolution and dedolomitization, while only calcite and dolomite dissolution/precipitation occurs in the BMK without dedolomitization. The hydrogeochemical data of the karst groundwaters were used to construct individual geochemical reaction models for each of the three different karst groundwater sub-systems. The modeling results confirm that dedolomization is the major process controlling hydrochemical changes in the XMK and the DMK. In the thermal groundwaters, the dissolution rates of fluorite, siderite and strontianite were found to exceed those of the cold karst groundwater systems, which can explain the higher concentrations of F−, Fe and Sr2+ that are found in these waters. 相似文献
7.
GIS and ANN coupling model: an innovative approach to evaluate vulnerability of karst water inrush in coalmines of north China 总被引：5，自引：0，他引：5
Evaporites, including rock salt (halite) and gypsum (or anhydrite), are the most soluble among common rocks; they dissolve
readily to form the same types of karst features that commonly are found in limestones and dolomites. Evaporites are present
in 32 of the 48 contiguous states in USA, and they underlie about 40% of the land area. Typical evaporite-karst features observed
in outcrops include sinkholes, caves, disappearing streams, and springs, whereas other evidence of active evaporite karst
includes surface-collapse structures and saline springs or saline plumes that result from salt dissolution. Many evaporites
also contain evidence of paleokarst, such as dissolution breccias, breccia pipes, slumped beds, and collapse structures. All
these natural karst phenomena can be sources of engineering or environmental problems. Dangerous sinkholes and caves can form
rapidly in evaporite rocks, or pre-existing karst features can be reactivated and open up (collapse) under certain hydrologic
conditions or when the land is put to new uses. Many karst features also propagate upward through overlying surficial deposits.
Human activities also have caused development of evaporite karst, primarily in salt deposits. Boreholes (petroleum tests or
solution-mining operations) or underground mines may enable unsaturated water to flow through or against salt deposits, either
intentionally or accidentally, thus allowing development of small to large dissolution cavities. If the dissolution cavity
is large enough and shallow enough, successive roof failures can cause land subsidence and/or catastrophic collapse. Evaporite
karst, natural and human-induced, is far more prevalent than is commonly believed. 相似文献
8.
人类活动影响下娘子关岩溶水系统地球化学演化 总被引：17，自引：5，他引：12
娘子关泉是我国北方最大的岩溶泉之一,也是阳泉市工农业生产和人民生活的重要供水水源。地下水地球化学演化分析表明,在地下水由补给区向排泄区运移过程中,除固有的水岩相互作用外,由于受采矿活动和地表水入渗补给的影响,岩溶水由低离子含量的HCO3-SO4或HCO3型水逐渐成为SO4型、SO4-HCO3型和SO4-HCO3-Cl型水。在泉群集中排泄区,区域流动系统与局部流动系统的地下水发生混合作用,最终形成了水质相对良好的HCO3-SO4型或SO4-HCO3型岩溶泉水。在此过程中,地下水对方解石和白云石也由最初的溶解作用演变为沉淀再结晶。尽管石膏呈持续溶解现象,但在采煤活动严重影响区域,石膏的沉淀也可能出现。地球化学模拟表明,在岩溶含水层中,地下水首先以方解石（白云石）的溶解为主;随着石膏溶解数量的增加,方解石（白云石）的溶解开始受到抑制,进而发生沉淀,石膏的溶解成为控制地下水水化学的主导过程。当矿坑水混入时,地下水相对石膏过饱和,地下水对碳酸盐岩含水介质的溶蚀能力得到增强。随着水岩反应的演进,铁氢氧化物大量沉淀,通过共沉淀和吸附作用去除了地下水中的重金属类污染物。 相似文献
9.
在分析区域地质、水文地质条件及水化学同位素的基础上,研究了山西娘子关泉域岩溶水的SO42-、硫同位素分布特征。研究表明:（1）泉域西北、西南地区岩溶水的SO42-主要来源于石膏的溶解;（2）泉域中部汇流区岩溶水的SO42-含量高而δ34S值低,其中的SO42-主要来源于煤系矿坑水,这是因为温河、桃河及南川河沿岸的岩溶水接受了被矿坑水污染的河水的渗漏补给以及部分地区受到钻孔串层污染;（3）娘子关泉群中城西泉水中的SO42-主要来源于煤系矿坑水,而五龙泉和集泉站水中的SO42-主要来源于石膏的溶解;（4）泉域东北部及东部河流沿岸以外的地区,岩溶水中的SO42-主要来源于大气降水、石膏溶解,并受到所处地层岩性的影响。 相似文献
10.
鄂尔多斯盆地下古生界马家沟组顶部遭受长期风化剥蚀,形成了以膏云岩为主的风化壳岩溶储层。通过偏光显微和超微扫描电镜深入观察了（含）膏云岩的孔隙类型及充填规律,分析了其岩溶作用特点,研究了以膏云岩为主的岩溶作用特征与传统碳酸盐岩岩溶作用特征的区别,探讨了膏云岩发育区的岩溶作用模式。结果表明:硬石膏结核和石膏晶体以其强亲水性和远高于白云石、方解石的溶解度,极易率先吸水发生溶解形成组构选择性溶蚀孔隙,导致膏云岩层蜂窝状溶孔的形成。硬石膏的高溶解度和力学不稳定性使得研究区以膏云岩、白云岩和灰云岩互层的风化壳储层以膏模孔、扩溶膏模孔及与之伴生的胀缩微裂缝为主要储集空间,孔隙大小具有明显的自限性。岩性—（含）膏云岩和沉积微相—海平面低位期潮上带（含）膏云坪沉积是储层形成的先天物质基础和环境条件,并因此直接导致（含）膏云岩储层的成层分布特征。表层膏云岩首先遭受淡水淋滤形成蜂窝状溶孔,多层成层分布膏云岩这种独特的物理化学性质使风化壳内的岩溶水以弥散性渗透为主,这是膏云岩发育区岩溶作用特征和模式与碳酸盐岩产生重要差异的根本原因。 相似文献
11.
目前,有关碳酸盐岩溶蚀过程的研究多集中在单一环境平衡状态下,不同赋存环境、微观尺度上的研究较少。鉴于此,为探讨不同赋存环境下碳酸盐岩溶蚀过程及微观变化特征,借助研制的岩溶水系统不同赋存环境下水岩相互作用模拟装置,选取典型岩溶水系统开放环境、半封闭环境与封闭环境的岩样,以CO2溶液为酸性流体介质,开展室内溶蚀模拟试验,研究岩溶水中特征组分的变化规律进行模拟实验,并从宏观和微观尺度,研究岩溶水系统不同赋存环境下的碳酸盐岩溶蚀变化特征。结果显示:不同赋存环境下Ca2+、HCO3-含量、饱和指数及pH值空间变化特征不同,各特征组分均呈现出随径流方向、溶蚀时间逐渐增大的趋势。不同赋存环境下,碳酸盐岩受水溶液中CO2含量的影响,在补给区的开放环境下溶蚀性最强,形成连通性较高的溶孔、溶隙。碳酸盐岩总溶蚀率均值是半开放环境的1.43倍,是封闭环境的2.70倍,半封闭与封闭环境下碳酸盐岩溶蚀后的微观结构介于孤立微孔与完全连通性溶隙之间。此外随深度的变化溶蚀量呈逐渐减弱的趋势,且浅部的变化更为明显。碳酸盐岩的溶蚀作用还受岩性控制,其随岩石中CaO/MgO比值的增大而增强。 相似文献
12.
The existing traditional methods of assessing the rates of soil loss have many limitations and are difficult to apply in the karst areas of Southwest China. Karst depressions comprise geomorphologically important sources and sinks for sediments and associated pollutants, yet the sedimentology of many depressions is not well understood. In this paper, the 137Cs technique was employed to investigate recent sedimentation rates in a Chinese polygonal karst depression. The results indicated that the sediment deposition rates ranged from 0.91 to 1.97 mm?a?1 in the period from 1963 to 2007, and the average sediment deposition rate and specific deposit yield of the catchment were estimated to be 1.47 mm?a?1 and 20 t?km?2?a?1, respectively. The results obtained were consistent with the local monitoring data of runoff plots, confirming the validity of the overall approach. It was shown that soil loss rates were very low in some karst areas of Southwest China. Above all, the approach appears to offer valuable potential to study surface erosion by estimating sediment deposition rates of karst depressions, rather than the assessment of complicated soil erosion in stony soils of carbonate rock slopes. In addition, the spacial distribution of surface soil and 137Cs inventories was affected remarkably by the inhomogeneous dissolution of limestone under the soil. It may be an important phenomenon which exists widely in the karst areas and is significantly different from other places. 相似文献
13.
Kerman city has a semiarid-arid climate with an average annual precipitation of about 158 mm. The area is underlain by soluble subsoil and alluvial deposits, overlying highly fractured Cretaceous limestones. Geo-environmental studies indicate that both paleokarst and active karst features are developed in the area. The paleokarsts were developed in the Upper Cretaceous limestone during the cold, humid periods of Post Cretaceous and probably Early Quaternary time and include honeycombs, solution flutes, rillenkarren, caverns, and solution collapse dolines. Active karst landforms occur by combined piping-induced and limestone solution at depth in subsoils, and alluvial deposits and bajada that overly potent karstic limestones and cover subsidence sinkholes and subjacent alluvial karst collapse dolines. Many factors, such as soluble compounds (salt and gypsum), desiccation cracks, and Qanat (dug water wells), could contribute to the development of karstic landforms. The most immediate cause for active karst landforms is considered to be the drawdown of the water table in the area. There is an increasing demand for groundwater consumption to irrigate pistachio fields. Excessive pumping of the groundwater lowers the water table about 80 cm per year. This rate of drawdown accelerates land subsidence (about 6 cm per year), creates circular patterns of fractures in the ground and in buildings, disrupts agricultural work and urbanization projects, and tilts foundations. These geohazards indicate that ground sinking and karstification are in progress in the alluvial deposits and underlying limestones. The disturbance and expense caused by the geohazards could be mitigated by the application of overhead sprinkler irrigation for pistachio fields or by planting less thirsty plants. 相似文献
14.
Jun Li Guoli Yang Danni Zhu Hao Xie Yi Zhao Lianjie Fan Shengzhang Zou 《Chemie der Erde / Geochemistry》2022,82(2):125866
Karst groundwater is a vital resource for drinking, living and irrigation purposes in karst agricultural areas of the world. Due to the vulnerability of karst aquifers, surface pollutants are easily transferred to the subsurface and make karst groundwater be deteriorated, thereby restricting the rational exploitation of karst groundwater resource. In view of this, 49 karst groundwater samples were collected from spring (SW) and underground river (URW) sites in the suburban area of Chongqing City and analyzed for various hydrochemical components. Particularly, the karst groundwater quality was comprehensively uncovered by combining characteristics of hydrogeochemical evolution and health risks caused by nitrate and fluoride. The results revealed that the karst groundwater was slightly alkaline in nature and the water types were mainly characterized by Ca-HCO3 accounting for 93.88% of the total samples due to the heavy dissolution of carbonate rock. The relatively high concentrations of Na+, SO42? and NO3? up to 271.88 mg/L, 277.94 mg/L and 56.94 mg/L were over the corresponding maximum acceptable limits for drinking water, which can be predominately attributed to the emissions of industrial park, dissolution of gypsum and pyrite and excessive application of chemical fertilizers. Although agricultural activities were stopped and chemical fertilizers were no longer applied during the sampling period, long-term application of fertilizers have a persistent adverse effect on the karst groundwater NO3?. The pollution index of the karst groundwater (PIG) revealed that the low pollution and potential pollution zones were noticed in the northwestern parts of the study area. With respect of the SW, all the total hazard index (HI) values were below 1 suggesting no significant health risk. On the contrary, HI values of 0.11–1.16 for adults, 0.15–1.61 for children and 0.17–1.83 for infants in the URW indicated significant noncarcinogenic health risks. Particularly, infants and children were more vulnerable to karst groundwater NO3? than adults. Furthermore, the noncarcinogenic health risks of karst groundwater can be mainly attributed to NO3?, confirmed by the higher contribution ratio (66.55%) to the HI values. Therefore, special and targeted measures need to be taken to decrease the NO3? concentration in agricultural area. 相似文献
15.
SO2-4浓度偏高是晋西柳林泉域岩溶水的主要特色之一,判断SO2-4来源对于理解岩溶水的水文地球化学过程具有重要意义。在分析区域地质、水文地质条件及岩溶水中SO2-4浓度空间分布特征的基础上,利用化学计量学法、同位素质量平衡模型和Rayleigh蒸馏模型,分析了岩溶水中SO2-4的主要来源,计算了不同来源的SO2-4所占的比例和滞流区岩溶水中SO2-4的还原比例。结果显示,石膏的溶解和黄铁矿的氧化是柳林泉域岩溶水中SO2-4的主要来源,排泄区岩溶水中石膏溶解来源的SO2-4所占比例介于73%~88%之间,平均为81%;黄铁矿氧化来源的SO2-4占比12%~27%,平均为19%。滞流区发生了硫酸盐的还原作用,约有9%~15%的SO2-4被脱硫细菌还原为H2S气体,且越靠近西部边界,还原反应所消耗的SO2-4比例越高。 相似文献
16.
Hydrochemical indications of human impact on karst groundwater in a subtropical karst area,Chongqing, China 总被引：4，自引：0，他引：4
Junbing Pu Min Cao Yuanzhu Zhang Daoxian Yuan Heping Zhao 《Environmental Earth Sciences》2014,72(5):1683-1695
The application of combined isotopic and hydrochemical compositions may be useful for evaluating water quality problems in karst aquifers in which it is difficult to distinguish the sources of solutes from the natural background of those due to human activities. Multiple isotopes (δ13C–DIC, δ34S–SO4 2?) and chemical parameters were measured in rainwater, groundwater and sewage in order to elucidate the solute sources and impacts from human activities and natural background in the Laolongdong karst catchment in Chongqing Municipality, SW China. Overall, the dissolution of carbonate rock controls Ca2+, Mg2+ and HCO3 ? content in rainwater and karst groundwater. SO4 2? originated mainly from gypsum dissolution in karst groundwater. Carbonate rocks in the studied site could be dissolved jointly by H2CO3 from the natural CO2–H2O reaction and other acids (organic acids and HNO3) from sewage and soils. Sewage discharge from urban areas and agriculture activities lead to the increase of NO3 ?, PO4 3? and Cl? in karst groundwater. To protect and sustainably utilize the karst aquifer, sewage originating from urban areas must be controlled and treated and the use of fertilizer should be limited. 相似文献
17.
Deep dissolution affects great part of soluble rocks (e.g. gypsum and anhydrite) of the Western Italian Alps. The related superficial phenomena (sinkholes, gravity-induced processes and a local worsening of geomechanical rock properties) are not limited to typical karsts landscape and cause slope instability also affecting populated sites and infrastructures. The paper aims to describe general characteristic of dissolution phenomena, to interpret their conditioning factors and evolutionary stages and to assess possible hazards due to their superficial effects.The search for evidences of deep dissolution leads to the selection of representative sites in the central part of the Western Italian Alps (Piemonte and Valle d'Aosta Region). Detailed geological and geomorphological studies have been used to classify the selected sites by type, size and variable state of activity. Very different evolutionary stages of dissolution phenomena have been interpreted by comparison of case-studies: some are early “embryonic”; others are more evolved, up to typical sinkholes, or even remodelled by other phenomena. Some cases show an extreme complexity in the interactions between corrosion phenomena and other geomorphic processes: slope deformations, from one side, and karst, fluvial and glacial phenomena, to the other. A wide range of movement rates on slope instabilities induced by deep dissolution have been estimated by topographic and geomorphic data. Geochemical data on removed rocks by dissolution indicate 0.4 mm/year values for local subsidence. Historical and technical data indicate low frequency of major dissolution-induced collapses, but highlight widespread damages to tunnels, roads and buildings, especially along slopes. 相似文献
18.
重庆中梁山碳酸盐岩溶蚀速率对季节的响应研究 总被引：2，自引：2，他引：0
在重庆市中梁山岩溶槽谷,选取林地、园地、耕地和菜地4种不同土地利用类型,通过野外下三叠统嘉陵江组白云质灰岩石试片的溶蚀试验分析不同土地利用方式下溶蚀速率对季节的响应关系。结果表明:不同土地利用方式将造成土壤性质发生不同的变化,进而对岩石的溶蚀速率产生明显的影响。但无论是从夏半年还是从全年来看,试片的溶蚀速率的大小变化均表现为:林地>菜地>耕地>园地。夏半年在全年的试片溶蚀作用过程中贡献较大,其绝对溶蚀量占全年比例都大于50%;除林地、菜地和园地土下50cm试片外,其余试片的夏半年溶蚀速率都大于全年溶蚀速率。究其原因,主要是由于夏半年气温高,降水量大,使土壤中CO2和水分等增加,从而有利于岩溶作用的进行 相似文献
19.
为研究溶蚀作用下碳酸盐岩孔隙的演变规律及控制作用,文章选取三峡地区4种类型碳酸盐岩开展溶蚀实验。同时结合扫描电镜、CT成像对实验前后岩石的溶蚀特征及孔隙结构进行测试。结果表明:溶蚀总发生在低晶格能的矿物处且沿矿物晶体的菱形解理面以及薄弱部位发育,表现为对矿物和孔隙等结构的选择性溶解;碳酸盐岩的孔隙度对溶蚀过程影响较小,岩石的孔径大小是影响碳酸盐岩溶蚀速率的重要因素;小孔径岩石的溶蚀多在样品表面发育小型溶孔,大孔径岩石的溶蚀主要发生在孔隙隙壁且有向岩石内部溶蚀的痕迹;经溶蚀改造,孔喉半径和连通性均呈现出增长趋势。本研究对碳酸盐岩差异性岩溶作用机理及岩溶发育规律的认识有一定指导意义。 相似文献
20.
Assessment of sediment and erosion rates by using the caesium-137 technique in a Chinese polygonal karst depression 总被引：4，自引：0，他引：4
Xiaoyong Bai 《Environmental Earth Sciences》2011,64(8):2151-2158
Karst depressions comprise geomorphologically important sources and sinks for sediments and associated pollutants; yet the
sedimentology of many depressions is not well understood in the world. In this paper, the 137Cs technique was employed to estimate recent sedimentation rates in a Chinese polygonal karst depression. The results indicate
that the sediment deposition rates ranged from 0.91 to 1.97 mm year−1 from 1963 to 2007, and the average sediment deposition rate and specific deposit yield were estimated to be 1.47 mm year−1 and 20 t km−2 year−1, respectively. These results are consistent with the local monitoring data of runoff fields, which confirms the validity
of the overall approach. This shows that the soil loss rate is very low in some karst areas of Southwest China. Above all,
the approach appears to offer valuable potential to study surface erosion by estimating sediment deposition rates of karst
depressions, rather than the assessment of complicated soil erosion in stony soils of carbonate rock slopes. In addition,
the space distribution of surface soil and 137Cs inventories are affected remarkably by the inhomogeneous dissolution of limestone under the soil. It may be an important
phenomenon, which exists widely in karst areas, and it is significantly different from other places. 相似文献