塔里木盆地奥陶系礁灰岩CO2毛细残余封存能力实验研究

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...     

Field testing of erodibility of two landslide dams triggered by the 12 May Wenchuan earthquake

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.     

沧州市深层水中氟离子变化与地层释水估算

沧州市地面沉降过程中地层压密释水导致水资源组成发生变化,这部分释水量是水均衡计算中必须要考虑的,但现有的调查数据并不明确。通过地下水中氟离子浓度的变化来解释地面沉降与弱透水层释水机理,并采用二元混合模型估算地下水开采资源组成中越流与释水所占份额。结果显示:沧州市承压含水层中氟离子浓度与地面沉降量存在着对应关系,在压缩释水阶段,开采量中有56%来自黏性土压密释水;在越流发生阶段,开采量中有36%来自越流补给。这表明压密黏性土释水是水资源评价的重要组成部分。     

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

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.     

The efficiency of artificial materials used for erosion control on steep slopes

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.     

肥城煤田白庄煤矿土地复垦适宜性评价方法探讨

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。     

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

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.     

Evidence for sediment recirculation on an ebb-tidal delta of the East Frisian barrier-island system, southern North Sea

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.     

Simulating impact of larch caterpillar (<Emphasis Type="Italic">Dendrolimus superans</Emphasis>) on fire regime and forest landscape in Da Hinggan Mountains,Northeast China

Larch caterpillar (Dendrolimus superans) is very common in the Da Hinggan Mountains, Northeast China, affecting fire regime and forest ecosystem change at large spatio-temporal scales. In this study, we used a spatially explicit landscape model, LANDIS, to simulate the changes of fire regime and forest landscape under four larch caterpillar disturbance intensity levels scenarios in Huzhong forest area, northern of Da Hinggan Mountains. The results indicate that larch caterpillar disturbances would decrease ...     

山东3次大暴雨过程云街雷达回波特征及其作用分析

利用济南多普勒天气雷达资料,结合探空与天气实况,对山东3次大暴雨过程中云街雷达回波特征和云街对于强降雨的作用进行了分析。结果表明:在天气雷达低层反射率因子上云街表现为多条窄带回波,走向与低层平均风场基本一致,持续时间约6～7 h,强度基本在5～20 dBz。云街对3次强降水的作用主要表现在3方面:一是触发机制,云街可触发对流单体;二是后向传播作用,云街新生对流单体依次沿云街走向向西南方向传播,具有明显后向传播特征,导致对流系统向西偏南方向发展,强降水区也向西偏南方向移动;三是利于降水强度增大和长时间的维持,持续不断的云街激发的雷暴,在移动过程中沿引导气流方向发展并与对流系统主体合并,主体回波得以发展与维持,产生大的雨强,并持续较长时间,导致极端强降雨天气。云街对3次强降水中尺度对流系统的维持与发展及极端强降雨的产生起到了重要作用。2007年7月18日过程云街触发雷暴的频次明显高于其他2次过程,主要原因是对流抑制能量和抬升凝结高度明显小于其他2次过程,更易于雷暴的触发。