松辽盆地隆起区地壳反射结构与“断开”莫霍界面

在我国松辽盆地内实施了4条近垂直反射地震法地壳精细结构探测, 获得了双程旅行时为15 s的松辽盆地地壳叠后偏移反射剖面. 重点研究松辽盆地东南隆起区与东北隆起区反射结构特征. 发现松辽盆地隆起区内整体上表现出：由西至东沉积层厚度变薄, 由北向南沉积层厚度增厚; 无论是东南隆起区还是东北隆起区, 壳内反射图案在南北向与东西向均变化剧烈; 东北隆起区莫霍界面双程反射旅行时变化范围为9.6~11.0 s, 深度范围为30~34 km, 东南隆起区莫霍界面双程反射旅行时变化范围为9.7~10.4 s, 深度范围为30~32 km. 由叠偏剖面资料分析可见松辽盆地隆起带内莫霍界面反射出现特异的断开特征, 错距达0.1~0.5 s, 约合2 km左右. 断开带附近存在多组剪切断裂并表现出隆起带内断开宽、两隆起带交界部位窄的空间分布规律. 这些反射图像与特异莫霍界面反射被推断为多期次黑龙江微陆块弱碰撞、太平洋板块向西俯冲等动力因素耦合作用的结果.     

Stream flow variability and drought severity in the Songhua River Basin,Northeast China

A slight variation in the magnitude of stream flow can have a substantial influence on the development of water resources. The Songhua River Basin (SRB) serves as a major grain commodity basin and is located in the northeastern region of China. Recent studies have identified a gradual decrease in stream flows, which presents a serious risk to water resources of the region. It is therefore necessary to assess the variation in stream flow and to predict the future of stream flows and droughts to make a comprehensive plan for agricultural irrigation. The simulation of monthly stream flows and the investigation of the influence of climate on the stream flow in the SRB were performed by utilizing the Integrated Water Evaluation and Planning (WEAP) tool coupled with observed precipitation data, as well as the Asian Precipitation-Highly-Resolved Observational Data Integration towards Evaluation of Water Resources (APHRODITE’s Water Resources) precipitation product. The Nash–Sutcliffe coefficient (NSC) was used to assess the WEAP efficiency. During the time of calibration, NSC was obtained as 0.90 and 0.67 using observed and APHRODITE precipitation data, respectively. The results indicate that WEAP can be used effectively in the SRB. The application of the model suggested a maximum decline in stream flow, reaching 24% until the end of 21st century under future climate change scenarios. The drought indices (standardized drought index and percent of normal index) demonstrated that chances of severe to extreme drought events are highest in 2059, 2060 and 2085, while in the remaining time period mild to moderate drought events may occur in the entire study area. The drought duration, severity and intensity for the period of 2011–2099 under all scenarios, [(A1B: 12, ? 1.55, ? 0.12), (A2: 12, ? 1.41, ? 0.09), (max. wetting and warming conditions: 12, ? 1.37, ? 0.11) and (min. wetting and warming conditions: 12, ? 1.69, ? 0.19)], respectively.     

Numerical investigation of the impact of uncertainties in satellite rainfall estimation and land surface model parameters on simulation of soil moisture

This study aims at evaluating the uncertainty in the prediction of soil moisture (1D, vertical column) from an offline land surface model (LSM) forced by hydro-meteorological and radiation data. We focus on two types of uncertainty: an input error due to satellite rainfall retrieval uncertainty, and, LSM soil-parametric error. The study is facilitated by in situ and remotely sensed data-driven (precipitation, radiation, soil moisture) simulation experiments comprising a LSM and stochastic models for error characterization. The parametric uncertainty is represented by the generalized likelihood uncertainty estimation (GLUE) technique, which models the parameter non-uniqueness against direct observations. Half-hourly infra-red (IR) sensor retrievals were used as satellite rainfall estimates. The IR rain retrieval uncertainty is characterized on the basis of a satellite rainfall error model (SREM). The combined uncertainty (i.e., SREM + GLUE) is compared with the partial assessment of uncertainty. It is found that precipitation (IR) error alone may explain moderate to low proportion of the soil moisture simulation uncertainty, depending on the level of model accuracy—50–60% for high model accuracy, and 20–30% for low model accuracy. Comparisons on the basis of two different sites also yielded an increase (50–100%) in soil moisture prediction uncertainty for the more vegetated site. This study exemplified the need for detailed investigations of the rainfall retrieval-modeling parameter error interaction within a comprehensive space-time stochastic framework for achieving optimal integration of satellite rain retrievals in land data assimilation systems.     

Developing a novel methodology for ecological risk assessment of thiosalts

A new methodology is developed to estimate an aquatic community toxicity threshold concentration based on the limited toxicity data that are available for thiosalts. To analyze the indirect effect of thiosalts on decreasing pH, an exposure model is developed that estimates the residual concentration of thiosalts and pH in the water body. The results from this model are incorporated in thiosalts risk assessment and a case study is used to illustrate the applicability of the proposed model. In this study, the exposure model predicts that, trithionate and tetrathionate degraded to $ {{\text{SO}}_{4}}^{2 - } $ ions, $ {{\text{HSO}}_{3}}^{ - } $ ions, $ {{\text{SO}}_{3}}^{2 - } $ ions and elemental sulfur. The concentration of thiosulfate, trithionate and tetrathionate, initially at 25, 40 and 6 mg/L, respectively are expected to decrease. Over the duration of 77 h, thiosulfate degrades completely, while the estimated residual trithionate and tetrathionate concentrations are 13 and 5.77 mg/L, respectively. pH of the undiluted effluent is estimated to decrease from 9.2 to 5.6 within an hour of the effluent discharge and decreases further to 4 over a period of next 3 days. A framework and methodology developed in this paper can be utilized to estimate the potential direct and indirect risk of thiosalts exposure to ecological entities.     

Origin of Quartz Cement in the Paleogene Sandstone Reservoir of Shahejie Formation, Bohai Bay Basin, China

The precipitation of authigenic quartz plays a significant role to reduce the reservoir characteristics and enhance the stiffness of the rock.The Es₁ sandstone of Shahejie Formation is acting as a significant hydrocarbon producing rock in the Nanpu Sag.Various methods like thin section petrography,cathodoluminescence(CL),scanning electron microscope(SEM,with EDS),and electron microprobe analysis has been used to reveal the origin of quartz cement as well as to evaluate the effect of quartz cement on reservoir quality.The studied sandstone is classified as immature to mature feldspathic litharenite and lithic arkose and consists of quartz,feldspar,rock fragments and micas.Petrographic studies and SEM analysis shows that the authigenic quartz is acting a significant cement that reduces the reservoir quality.Whereas clay minerals(kaolinite and mixed layer illite to smectite)are dominant in the Es₁ sandstone,that can reduce the reservoir quality.SEM,CL and thin section analysis reveal that there are two stages of quartz cement in the studied samples;that are pore filling authigenic cement and quartz overgrowth cement.Fluid inclusion homogenization temperatures shows that stages of quartz cement were developed with continuous process from 70℃ to 130℃.Quartz cements were generally originated from I/S reaction,feldspar dissolution,conversion of rock fragments and pressure solution.Feldspar dissolution(K-feldspar)and kaolinite to illite reaction is an insignificant silica source for the silica cement which is internally precipitated in a close system with diffusion transporting mechanism.Overall,quartz cement significantly enhance the rock strengthen and brittleness effectively as well as it reduce the overall reservoir quality.     

Numerical simulation of fabric anisotropy and strain localization of sand under simple shear

This paper studies the effects of initial fabric anisotropy of dry sand in simple shear deformation. The effects of anisotropy are taken into consideration through the modification of the mobilized friction in the Mohr–Coulomb‐type yield surface as a function of a fabric parameter. In addition, the constitutive model uses a gradient term that directly incorporates the effects of material length scale. The constitutive formulation is implemented into ABAQUS finite element code and used to simulate shearing of the dry sand under various conditions of simple shear. The numerical simulations show that while the shear stress response is affected by fabric anisotropy, its effects on strain localization in simple shear are minimal. This is in contrast to other devices such as the biaxial shear. The strain localization in simple shear is controlled more by the imposed boundary conditions. The use of material length scale is shown to remove the effects of strain localization in the shearing response. Copyright © 2009 John Wiley & Sons, Ltd.     

Confirming Ground Geophysical Survey for Mineralization in Al Bayda Area, Yemen

The Jabal Mabal-prospect of Al Bayda area is covered by meta-volcano sedimentary rocks. The importance of the study area comes from previous studies, which proved that the area has mineralization zones at the periphery of Jabal Al-Mabal. These mineralized zones lie along northwest-southeast shear zones, which occur inside the meta-volcanic rocks. The previous studies concluded that the mineralization was mostly associated with sulphides, especially at the reduction zones. These sulphides give a good response to electrical or electromagnetic techniques. The present study uses electrically induced polarization and Genie electromagnetic surveys to explore the extension of the mineralization zones at the subsurface. The self-potential (SP) technique shows numerous of mineralized zones. Most of these zones are distributed in the southern area along the contact between the quartz and gabbro. The induced polarization (IP) method has been applied on the selected profiles to delineate the subsurface contact between calcite, gabbro and quartz in Al-Jarra Valley and to calculate the shape and depth of the mineralization zones in the subsurface along these profiles. The Genie electromagnetic survey, which has been applied on selected profiles, delineated some weak mineralization occurrences corresponding to the shear zones. The integration of the results obtained using these three techniques, in addition to the different ground geophysical methods previously used, makes it possible to determine the most appropriate zones for development of exploration at the area of investigation.     

Transport phenomena in kaolinite clay: Molecular simulation,homogenization analysis and similitude law

Kaolinite is a common clay mineral. It is a nanomaterial with a platelet crystalline structure. In order to analyze the behavior of kaolinite, its microscopic structure and material properties must be specified correctly. A molecular dynamics (MD) simulation is used for determining the microscale properties of hydrated kaolinite, and these properties are introduced into a multiscale homogenization analysis (HA). We previously developed such an MD/HA technique to investigate seepage, diffusion, sorption and consolidation in bentonite clay (Proceedings of the Science Basis for Nuclear Waste Management, Davos, Switzerland, vol. XXI. Material Research Society: Warrendale, PA, 1997; 359–366; Eng. Geol. 1999; 54 :21–31; Eng. Geol. 2001; 60 :127–138; Coupled Thermo‐Hydro‐Mechanical‐Chemical Processes in Geo‐systems. Elsevier: Amsterdam, 2005; 457–464). We here apply the method to kaolinite clay to investigate the permeability, diffusion and related similitude law. The obtained results are supported by existing experimental data. Copyright © 2008 John Wiley & Sons, Ltd.     

The emerging role of satellite rainfall data in improving the hydro-political situation of flood monitoring in the under-developed regions of the world

The systematic decline of in situ networks for hydrologic measurements has been recognized as a crucial limitation to advancing hydrologic monitoring in medium to large basins, especially those that are already sparsely instrumented. As a collective response, sections of the hydrologic community have recently forged partnerships for the development of space-borne missions for cost-effective, yet global, hydrologic measurements by building upon the technological advancements since the last two decades. In this article, we review the state-of-the-art on flood monitoring in medium and large ungauged basins where satellite remote sensing can facilitate development of a cost-effective mechanism. We present our review in the context of the current hydro-political situation of flood monitoring in flood-prone developing nations situated in international river basins (IRBs). Given the large number of such basins and the difficulty in acquisition of multi-faceted geophysical data, we argue that the conventional data-intensive implementation of physically based hydrologic models that are complex and distributed is time-consuming for global assessment of the utility of proposed global satellite hydrologic missions. A more parsimonious approach is justified at the tolerable expense of accuracy before such missions begin operation. Such a parsimonious approach can subsequently motivate the identified international basins to invest greater effort in conventional and detailed hydrologic studies to design a prototype flood forecasting system in an effort to overcome the hydro-political hurdles to flood monitoring. Through a modeling exercise involving an open-book watershed concept, we demonstrate the value of a parsimonious approach in understanding the utility of NASA-derived satellite rainfall products. It is critical now that real-world operational flood forecasting agencies in the under-developed world come forward to collaborate with the research community in order to leverage satellite rainfall data for greater societal benefit for inhabitants in IRBs.     

Socio-economic determinants of women’s livelihood time use in rural Bangladesh

Achieving gender well-being and equality is one of the 17 Sustainable Development Goals of the United Nations. A close examination of female livelihood time allocation can reveal gender inequality in livelihood choices between males and females. Using the feminist political ecology framework, this paper examines how gendered knowledge, roles, and responsibilities influence female livelihood time use in a patriarchal society like Bangladesh. We use a nationally representative household survey data to create Multiple Linear Regression Model to understand the association between economic, cultural, and environmental shocks with the total time allocation toward livelihood activities by women. Our results suggest that use of ‘Purdah’ by Muslim women acts as a negative detrimental factor towards their livelihood time allocation, thus affirming the complex role of culture and gendered economic activities. Women also allocate less time toward livelihood activities during pregnancy and/or breastfeeding. We find that female livelihood time use also depends on their ability to speak in public, their autonomy in livelihood decision processes, and their ownership in business enterprises. This research suggests creating more robust and gender sensitive policies in Bangladesh that can help achieve the United Nation’s goals of Sustainable Development.