西昆仑山甜水海北湖砂楔的形成与环境演变   总被引：1，自引：0，他引：1       下载免费PDF全文

常晓丽  金会军  何瑞霞 《第四纪研究》2011,31(1):112-119

青藏高原是世界上中低纬度地区冰缘最发育的区域,其中西昆仑山甜水海地区广泛分布着砂楔群等冰缘现象.砂楔是寒冷气候条件的产物,对古气候和古环境的重建具有重要意义.文章通过分析甜水海北湖砂楔矿物特征发现,砂楔填充物基本属于近源堆积;14C测年结果以及粒度再结合砂楔形态分析得出,该砂楔的形成经历了13.9kaB.P.,11.9...  相似文献   

下辽河平原南部明化镇组咸水体赋存条件及分布特征     

刘畅  潘俊  李洋  孟思翘 《地下水》2011,33(3):11-12,76

下辽河平原南部自上世纪七十年代以来陆续开采了上第三系明化镇组深层地下水,开采至今暴露出一系列的问题,如区域地下水头下降较快形成大面积水头降落、局部出现咸水体扩张及淡水咸化问题,严重威胁该地区居民的淡水资源安全.通过对下辽河平原南部上第三系地下水明化镇组含水层咸水体赋存的地质地貌、补迳排条件、动态特征等进行研究,掌握其赋...  相似文献   

塔里木盆地奥陶系礁灰岩CO2毛细残余封存能力实验研究   总被引：1，自引：0，他引：1       下载免费PDF全文

李旭峰  常春  郭建强  于青春 《地学前缘》2011,18(6):190-194

实施CO2地质封存是目前公认的减少温室气体排放的有效方法。在可能进行封存的场所中,咸水含水层封存潜力最大,机理也最为复杂。其中毛细残余封存机理在封存量和封存安全性方面均具有十分重要的意义。在评价毛细残余封存量时,残余气饱和度是一个十分重要的参数。文中提出了测定残余气饱和度的实验方法,并实际应用于中国塔里木盆地奥陶系礁灰...  相似文献   

Field testing of erodibility of two landslide dams triggered by the 12 May Wenchuan earthquake   总被引：4，自引：3，他引：1  

D. S. Chang  L. M. Zhang  Y. Xu  R. Q. Huang 《Landslides》2011,8(3):321-332

A strong earthquake of magnitude 8 in Richter scale, occurred in Sichuan Province, China on 12 May 2008, triggered about 257 landslide dams. The erodibility of fresh landslide deposits plays an important role in evaluating the initiation and development of breaching of such landslide dams. In this research, field jet index tests were conducted shortly after the earthquake at 27 locations on the Hongshihe landslide dam and the Libaisi landslide dam. The purpose of these tests was to investigate the erodibility of freshly deposited landslide soils. The landslide deposits are broadly graded. The bulk density increases and the coefficient of erodibility decreases with the depth of deposition. The erodibility of the fresh landslide deposits falls into a moderately resistant category and the fresh deposits are much more erodible than the native geomaterials before the earthquake. The main factors that control soil erodibility are found to be grain-size distribution, void ratio, fines content, and plasticity index. Particularly, the coefficient of erodibility decreases exponentially with the degree of compaction. Two empirical equations are developed for estimating the coefficient of erodibility and critical erosive shear stress of the freshly deposited landslide soils based on their basic soil properties.  相似文献   

Modeling spatial uncertainty of heavy metal content in soil by conditional Latin hypercube sampling and geostatistical simulation     

Yu-Pin Lin  Hone-Jay Chu  Yu-Long Huang  Bai-You Cheng  Tsun-Kuo Chang 《Environmental Earth Sciences》2011,62(2):299-311

This study proposes the method of simulating spatial patterns and quantifying the uncertainty in multivariate distribution of heavy metals (Cr, Cu, Ni, and Zn) by sequential indicator simulation (SIS) combined with conditional Latin hypercube sampling (cLHS) in Changhua County, Taiwan. The cLHS is used for a sampling then for SIS mapping and assessing uncertainties of heavy metal concentrations. The indicator variogram results indicate that the 700 cLHS samples replicate statistical multivariate distribution and spatial structure of the 1,082 samples. Moreover, the SIS realizations based on 700 cLHS samples are more conservative and reliable than those based on 1,082 samples for delineating soil contamination by all heavy metals with the exception of Zn. Given adequate sampling, soil contamination simulation provides sufficient information for delineating contaminated areas and planning environmental management.  相似文献   

The efficiency of artificial materials used for erosion control on steep slopes   总被引：2，自引：1，他引：1  

Su-Chin Chen  Kuang-Tsung Chang  Shi-Hao Wang  Jun-Yue Lin 《Environmental Earth Sciences》2011,62(1):197-206

This study investigates the performance of artificial materials used for erosion control on steep slopes under high rainfall intensity. Soil samples were laid on a 300 × 100 cm platform inclined at either 35° or 45°, after which the soil was covered with various materials and subjected to a rainfall intensity of 130 mm/h for an hour. A wooden-block net covered with a jute net resulted in the greatest erosion resistance, providing 83% resistance at 35° and 76% at 45°. On the 35° slope, the artificial materials showed relatively good erosion resistance. As the slope was raised to 45°, some of the materials did not attach effectively to the soil surface. Thus, the runoff velocity increased and erosion became severe. For optimum erosion resistance, the material used to protect soil must attach to the soil surface well and have structural properties, such as a high coverage ratio to reduce the impact of rainfall on the soil and uniformly distributed transverse structures to reduce runoff energy and trap soil.  相似文献   

Research on the water use efficiency and foliar nutrient status of <Emphasis Type="Italic">Populus euphratica</Emphasis> and <Emphasis Type="Italic">Tamarix ramosissima</Emphasis> in the extreme arid region of China     

Sheng Kui Cao  Qi Feng  Yong Hong Su  Zong Qiang Chang  Hai Yang Xi 《Environmental Earth Sciences》2011,62(8):1597-1607

Seasonal variations in foliar stable carbon composition (δ¹³C) and nitrogen (N), phosphorus (P) and potassium (K) concentrations of Populus euphratica Olivier and Tamarix ramosissima Ledeb, as well as correlations between foliar δ¹³C values and N, P and K concentrations were studied in the Ejina oasis in the lower reaches of the Heihe River, northwestern China. Foliar δ¹³C values, and P and K concentrations significantly differed between species. Foliar δ¹³C signatures in T. ramosissima were significantly more enriched than those in P. euphratica, but P and K concentrations of P. euphratica were higher. The seasonal variations and patterns of these were similar. The total foliar δ¹³C values and N, P and K concentrations in both P. euphratica and T. ramosissima showed a descending trend. There were significantly positive correlations between foliar δ¹³C values and N and P concentration of both P. euphratica and T. ramosissima. For the relationship between foliar δ¹³C and K concentration, there appeared oppositely positive and negative correlations in P. euphratica and T. ramosissima, respectively, but they were not significant. The simple positive correlations of δ¹³C–P% and δ¹³C–N% suggested that N and P in P. euphratica and T. ramosissima behave in a similar manner. This study also showed that there were nutrient deficiencies; N and P nutriments were the co-limiting factors in P. euphratica, while it was P nutriment in T. ramosissima.  相似文献   

肥城煤田白庄煤矿土地复垦适宜性评价方法探讨     

谭肖波  薄本玉  张敏  朱昶 《山东地质》2011,(6):36-40

土地复垦适宜性评价是土地复垦方案编制过程中至关重要的环节,该文以白庄煤矿为例,在分析土地复垦相关因素的前提下,遵循一定的评价原则,制定了土地复垦适宜性评价的方法和步骤,并最终确定了复垦区各单元的复垦方向,对同类地区土地复垦方案的编制具有一定的参考价值。  相似文献   

Compact high-resolution temperature loggers for measuring the thermal gradients of marine sediments     

Hung-I Chang  Chuen-Tien Shyu 《Marine Geophysical Researches》2011,32(4):465-479

Currently, two major types of ship-operated underwater instruments are used for heat flow measurements including a Lister-type heat probe (LTHP) and small temperature loggers (STLs) that are attached to a solid-steel lance or a core barrel. In both operations, penetration friction heat introduces a transient disturbance to the temperature of the surrounding sediments. A pragmatic approach is to extrapolate a cylindrical temperature decay function to estimate the equilibrium ambient temperature (EAT) and equilibrium ambient temperature gradient (EATG) of the sediments from short temperature recordings. The extrapolated EAT and EATG will greatly affect the estimate of the base of the gas hydrate stability zone (BGHS). In order to achieve a better extrapolation of EAT, EATG, and 1-s temperature sampling requirements, compact (22.2 cm × 2.2 cm) high-resolution temperature loggers (CHTLs) have been designed to work with a sediment core barrel. The mechanical and electronic design of the CHTL is detailed in the text. With a 24-bit, low noise A/D converter embedded in the mix-signal microprocessor, including a highly stable reference resistor based ratiometric scheme, the CHTL is capable of resolving 0.1 m°C in the range of −1 to 25°C. It has a memory capacity of 4 Mbyte which can work continually up to 16 days with a 1-s sampling interval. From a data processing efficiency consideration, field experiments indicate that adopting short support fins to attach the CHTLs to a relatively small size core barrel is better than using high support fins. A similar approach such as extrapolating the cylindrical temperature decay function to estimate EAT, EATG can be obtained from regressing a direct calculated temperature gradient of short recorded data. The resulting EATG accuracy may be significantly improved through the application of the proposed correction formula and therefore is much better than that which is directly calculated from the extrapolated EATs.  相似文献   

Evidence for sediment recirculation on an ebb-tidal delta of the East Frisian barrier-island system, southern North Sea   总被引：2，自引：2，他引：0  

Chang Soo Son  Burghard W. Flemming  Alexander Bartholom? 《Geo-Marine Letters》2011,31(2):87-100

The Otzum ebb-tidal delta, located between Langeoog and Spiekeroog islands along the East Frisian barrier-island coast, southern North Sea, was investigated with respect to its morphological evolution, sediment distribution patterns and internal sedimentary structures. Bathymetric charts reveal that, over the last 50 years, the size of the Otzum ebb-tidal delta has slightly shrunk, while sediment has accreted on the ebb-delta lobe to the east of the main inlet channel (west of Spiekeroog). Swash bars superimposed on the eastern ebb-tidal shoal (Robben Plate) have migrated south or south-eastwards, i.e. towards the inlet throat. The main ebb-delta body is composed of fine quartz sand, whereas the superimposed swash bars and the inlet channel bed consist of medium-grained quartz sand containing high proportions of coarser bioclastic material. Internal sedimentary structures in short box-cores (up to 30 cm long) are dominated by flood-oriented cross-beds. Longer vibro-cores (up to 1.5 m long) show that, at depth, the sediment is dominated by storm-generated parallel (upper plane bed) laminations with intercalated shell layers and dune cross-bedding. The cross-bedded sands in both box-cores and vibro-cores from the ebb-delta shoal predominantly dip towards the south or southeast, indicating transport towards the inlet throat by the flood current. The observations demonstrate that, contrary to previous contentions, the sediments of the highly mobile swash bars do not bypass the inlet but are instead being continually recirculated by the combined action of tidal currents and waves. In this model, the cycle begins with both fine and medium sands, including shell hash, being transported seawards in the main ebb channel until they reach the shallow ebb-delta front. From here, the sediment is pushed onto the eastern ebb-delta shoal by the flood current assisted by waves, becoming strongly size-sorted in the process. The medium sands together with the shell hash are formed into swash bars which migrate along arcuate paths over a base of fine sand back to the main ebb channel located south of the ebb delta. By the same token, the fine sand between the swash bars is transported south-eastwards by the flood current in the form of small dunes until it cascades into the large flood channel located to the west of Spiekeroog. From here, the fine sand is fed back into the main ebb channel, thus completing the cycle. No evidence was found on the ebb delta for alongshore sediment bypassing.  相似文献