Monitoring Large-Scale Tests for Nuclear Waste Disposal

Two large-scale “in situ” demonstration experiments and their instrumentation are described. The first test (FEBEX Experiment) involves the hydration of a compacted bentonite barrier under the combined effect of an inner source of heat and an outer water flow from the confining saturated granite rock. In the second case, the progressive de-saturation of Opalinus clay induced by maintained ventilation of an unlined tunnel is analyzed. The paper shows the performance of different sensors (capacitive cells, psychrometers, TDR’s) and a comparison of fill behaviour with modelling results. The long term performance of some instruments could also be evaluated specially in the case of FEBEX test. Capacitive sensors provide relative humidity data during long transient periods characterised by very large variations of suction within the bentonite.     

GPS时间序列分析

GPS时间序列可以用于获取各种地球物理现象、地壳运动的季节性变化规律和板块运动的速度,对地球动力学的研究具有相当重要的意义。本文详细阐述了GPS时间序列分析的方法及其过程,对国内IGS站数据的时间序列进行了分析,并运用功率谱分析其残差时间序列,最后获得GPS连续跟踪站时间序列的噪声类型。     

Impact of satellite observed microwave SST on the simulation of tropical cyclones

The impact of realistic representation of sea surface temperature (SST) on the numerical simulation of track and intensity of tropical cyclones formed over the north Indian Ocean is studied using the Weather Research and Forecast (WRF) model. We have selected two intense tropical cyclones formed over the Bay of Bengal for studying the SST impact. Two different sets of SSTs were used in this study: one from TRMM Microwave Imager (TMI) satellite and other is the weekly averaged Reynold’s SST analysis from National Center for Environmental Prediction (NCEP). WRF simulations were conducted using the Reynold’s and TMI SST as model boundary condition for the two cyclone cases selected. The TMI SST which has a better temporal and spatial resolution showed sharper gradient when compared to the Reynold’s SST. The use of TMI SST improved the WRF cyclone intensity prediction when compared to that using Reynold’s SST for both the cases studied. The improvements in intensity were mainly due to the improved prediction of surface latent and sensible heat fluxes. The use of TMI SST in place of Reynold’s SST improved cyclone track prediction for Orissa super cyclone but slightly degraded track prediction for cyclone Mala. The present modeling study supports the well established notion that the horizontal SST gradient is one of the major driving forces for the intensification and movement of tropical cyclones over the Indian Ocean.     

Middle Miocene aquatic and wetland vegetation of the paleosinkhole at Tarnów Opolski,SW Poland

I analyzed spores, pollen and organic-walled algal remains in Middle Miocene deposits that filled a paleosinkhole at Tarnów Opolski, in the Upper Silesian Upland, Poland. Middle Triassic limestone bedrock in the study area underwent intense karstification under relatively warm and humid climate, resulting in development of numerous sinkholes. As the corrosion reached non-karstified marls, flowing water in the vadose zone was plugged and meteoric waters thus accumulated, leading to pond development. This palaeobotanical study was undertaken to “reconstruct” the fossil freshwater algae community and vegetation in and around the water body. Chlorophyta such as Botryococcus, filamentous algae from the family Zygnemataceae, mainly Mougeotia, Spirogyra and Zygnema, and desmids were important components of the algal assemblage. Most of the identified algae prefer mesotrophic to eutrophic conditions, and are characteristic of stagnant or slow-flowing shallow water. Among the free-floating and rooted plants were Salviniaceae/Azollaceae (probably Salvinia), Nuphar, Potamogeton, and carnivorous taxa such as Utricularia and probably Aldrovanda. The water body was surrounded by swamp vegetation composed of herbs such as Typha, Sparganium, Alismataceae and others, and riparian forests. The upper portion of the sediment section contains abundant pollen of swamp forest taxa such as Taxodium/Glyptostrobus, Nyssa and Alnus. The paleobotanical remains from the sinkhole at Tarnów Opolski suggest it was a shallow water body that was probably prone to rapid warming. Presence of resting cells, e.g. zygospores of Zygnemataceae and desmids, suggests that the pond may have dried periodically. Presence of Nuphar, Utricularia and Aldrovanda pollen, however, indicates long periods with standing water.     

PCA and SVM as geo-computational methods for geological mapping in the southern of Tunisia,using ASTER remote sensing data set

The purpose of this study was to examine the efficiency of Advanced Space Borne Thermal Emission and Reflection Radiometer (ASTER) data in the discrimination of geological formations and the generation of geological map in the northern margin of the Tunisian desert. The nine ASTER bands covering the visible (VIS), near-infrared (NIR) and short-wave infrared (SWIR) spectral regions (wavelength range of 400–2500 nm) have been treated and analyzed. As a first step of data processing, crosstalk correction, resampling, orthorectification, atmospheric correction, and radiometric normalization have been applied to the ASTER radiance data. Then, to decrease the redundancy information in highly correlated bands, the principal component analysis (PCA) has been applied on the nine ASTER bands. The results of PCA allow the validation and the rectification of the lithological boundaries already published on the geologic map, and gives a new information for identifying new lithological units corresponding to superficial formations previously undiscovered. The application of a supervised classification on the principal components image using a support vector machine (SVM) algorithm shows good correlation with the reference geologic map. The overall classification accuracy is 73 % and the kappa coefficient equals to 0.71. The processing of ASTER remote sensing data set by PCA and SVM can be employed as an effective tool for geological mapping in arid regions.     

Ra’s Abdah of the north Eastern Desert of Egypt: the role of granitic dykes in the formation of radioactive mineralization,evidenced by zircon morphology and chemistry

Syenogranitic dykes in the north of Egypt’s Eastern Desert are of geological and economic interest because of the presence of magmatic and supergene enrichment of radioactive mineralization. Zircon crystal morphology within the syenogranitic dykes allows precise definition of sub-alkaline series granites and crystallized at mean temperature of about 637 °C. The growth pattern of the zircons suggest magmatic and hydrothermal origins of radioactive mineralization. Hydrothermal processes are responsible for the formation of significant zircon overgrowth; high U-zircon margins might have occurred contemporaneously with the emplacement of syenogranitic dykes which show anomalous uranium (eU) and thorium (eTh) contents of up to 1386 and 7330 ppm, respectively. Zircon chemistry revealed a relative increase of Hf consistent with decreasing Zr content, suggesting the replacement of Zr by Hf during hydrothermal activity. Visible uranium mineralization is present and recognized by the presence of uranophane and autunite.     

预应力混凝土渡槽抗震性能的试验研究

基于预应力混凝土渡槽的低周反复荷载试验,对其受力过程、破坏形态、滞回曲线、刚度退化、耗能能力等抗震性能进行了研究与分析。试验结果表明：预应力混凝土渡槽的破坏形态为弯剪破坏,滞回曲线在加载的初期阶段表现出一定的捏拢效应,滞回曲线总体呈明显的梭形,且较为丰满,耗能能力强,抗震性能优良;配筋合适的预应力混凝土渡槽在加载初期对裂缝控制具有良好的表现,渡槽整体具有良好的延性;在整个加载过程中,渡槽试件的刚度退化明显,刚度退化主要集中在开裂后至屈服这一阶段。     

Sublethal Effects of Crude Oil on the Community Structure of Estuarine Phytoplankton

While the ecological impacts of crude oil exposure have been widely studied, its sublethal effects on phytoplankton community structure in salt marsh estuaries have not been well documented. The purpose of this study was to simulate oil spill conditions using a microcosm design to examine short-term (2 day) changes in phytoplankton community composition and total biomass following exposure to crude oil obtained from the Deepwater Horizon oil spill and a mixture of Texas crude oils. Microcosm experiments were performed in situ in North Inlet Estuary near Georgetown, SC. A control and six replicated experimental treatments of crude oil additions at final concentrations of 10, 50, or 100 μl l⁻¹ of either Deepwater Horizon spill oil or the Texas crude mixture were incubated under in situ conditions. Photopigments were analyzed using high-performance liquid chromatography and community composition was determined using ChemTax. Total phytoplankton biomass (as chl a) declined with increasing crude oil concentrations. Prasinophytes, the most abundant microalga in both experiments, showed no response to oil exposure in one experiment and a significant negative response in the other. Diatoms euglenophytes and chlorophytes appeared relatively resistant to oil contamination at the exposure levels used in this study, maintaining or increasing their relative abundance with increasing oil concentrations. Chlorophytes and cyanobacteria increased in relative abundance while cryptophyte abundance decreased with increasing oil concentrations. The results of these experiments suggest that low levels of crude oil exposure may reduce total biomass and alter phytoplankton community composition with possible cascade effects at higher trophic levels in salt marsh estuaries.     

Polycyclic aromatic hydrocarbon concentrations in urban soils representing different land use categories in Shanghai

An extensive soil survey was carried out in Shanghai to investigate the spatial distribution and possible sources of polycyclic aromatic hydrocarbons (PAHs) in urban soils. Soil samples were collected from highways, iron-smelting plants, steel-smelting plants, shipbuilding yards, coking plants, power plants, chemical plants, urban parks, university campuses and residential areas and were analyzed for 16 PAHs by gas chromatography with mass detection. High PAH concentrations were found in all locations investigated, with mean values of soil total PAH concentrations in the range 3,279–38,868 μg/kg DM, and the PAH concentrations were significantly influenced by soil organic matter content. Soil PAH profiles in all districts were dominated by PAHs with 4–6 rings. Principal components analysis and diagnostic ratios of PAHs indicate that they were mainly derived from coal combustion and petroleum but in soils from highways the PAHs were derived largely from vehicle exhaust emissions. The high concentrations of PAHs found indicate that many urban soils in Shanghai represent a potential hazard to public health.     

班公湖-怒江缝合带西段阿翁错地区中酸性侵入岩的成因及其对区域构造演化的指示

班公湖-怒江缝合带西段出露大量中酸性侵入岩,为特提斯洋俯冲、拉萨地块与羌塘地块碰撞造山过程中岩浆响应的重要组成部分。本文对该缝合带西段阿翁错地区的闪长岩、花岗闪长岩和花岗岩进行了详细的岩石地球化学和锆石U-Pb年代学研究。锆石LA-ICP-MS U-Pb定年结果表明闪长岩、花岗闪长岩、花岗岩成岩年龄分别为119.3±1.8 Ma、114.7±1.4 Ma和103.2±1.3 Ma。岩石地球化学特征显示中酸性侵入岩属高钾钙碱性系列,具准铝质-弱过铝质I型花岗岩特征;其LREE分馏程度较高,而HREE近于平坦,存在Eu负异常;富集Rb、La等大离子亲石元素和Th、Zr、Hf等高场强元素,亏损Nb、Ta、P、Ti等高场强元素,具有岛弧岩浆岩的特征。研究结果表明在早白垩世晚期(103.0±1.3 Ma)班公湖-怒江特提斯洋壳仍在向北俯冲于南羌塘地块之下,随着俯冲深度增加,大洋板片发生大规模脱水,释放的流体交代地幔楔并引发其部分熔融,产生的幔源岩浆向上运移,与下地壳物质不同比例混合形成了闪长岩和花岗闪长岩;而花岗岩主要由古老下地壳物质部分熔融形成,并有少量地幔物质的参与。