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41.
The design of a top-cover system is a very important aspect of the closure of sanitary landfills. Soil material properties, sequencing, and vegetation are critical to top-cover design. To date, very few field investigations have been undertaken to determine the effectiveness of these designs. Results from a field investigation of top-covers proposed for an active landfill site in south Florida are reported here. Measurements were made of each component of the water balance equation: S = [P +I] – [ET +R +Q] whereS, P, I, ET, R, andQ represent water storage, rainfall, irrigation, evapotranspiration, surface runoff, and deep seepage, respectively. Deep seepage, determined using soil water tensiometers, is the amount of water infiltrating the landfill top-cover and is therefore the upper limit of potential leachate generation.Results indicate that the locally available rock tailings (carbonate silt) is an effective topliner component of the top-cover system. The results of the field investigation also showed that the EPA water balance model used to estimate infiltration during landfill design was greater than the actual field measurements.  相似文献   
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The paper describes a model, which estimates the risk levels of individual crude oil tankers. The intended use of the model, which is ready for trial implementation at The Norwegian Coastal Administrations new Vard? VTS (Vessel Traffic Service) centre, is to facilitate the comparison of ships and to support a risk based decision on which ships to focus attention on. For a VTS operator, tasked with monitoring hundreds of ships, this is a valuable decision support tool. The model answers the question, "Which ships are likely to produce an oil spill accident, and how much is it likely to spill?".  相似文献   
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The Greenland shark (Somniosus microcephalus) is a high-trophic fish species present in Arctic waters. The present study aimed to determine concentrations of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs), dioxin-like (DL) PCBs and six non-dioxin-like (NDL) PCBs in muscle and liver from 10 female Greenland sharks collected between 2001 and 2003 from Icelandic waters. The mean total concentrations of PCDDs/Fs were 13 and 530pg/g fat for muscle and liver, respectively, and show enrichment in the liver. Concentrations of DL-non-ortho PCBs were also higher in liver compared to muscle with mean concentrations of 7.8 and 0.36ng/g fat, respectively. No enrichment in the liver was found for DL-mono-ortho- and NDL-PCBs. No correlation was found between the size range studied and total concentrations of the compounds analyzed. Total WHO-TEQs (PCDDs/Fs and DL-PCBs) ranged between 7.1-70 and 54-1500pg/g fat in muscle and liver, respectively.  相似文献   
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Prevention of oil spill from shipping by modelling of dynamic risk   总被引:1,自引:0,他引:1  
This paper presents a new dynamic environmental risk model, with intended use within a new, dynamical approach for risk based ship traffic prioritisation. The philosophy behind this newly developed approach is that shipping risk can be reduced by directing efforts towards ships and areas that have been identified as high priority (high risk), prior to a potential accident. The risk model proposed in this paper separates itself from previous models by drawing on available information on dynamic factors and by focusing on the ship's surroundings. The model estimates the environmental risk of drift grounding accidents for oil tankers in real time and in forecast mode, combining the probability of grounding with oil spill impact on the coastline. Results show that the inherent dynamic risk introduced by an oil tanker sailing along the North Norwegian coast depends, not surprisingly, significantly upon wind and ocean currents, as well as tug position and cargo oil type. Results of this study indicate that the risk model is well suited for real time risk assessment, and effectively separates low risk and high risk situations. The model is well suited as a tool to prioritise oil tankers and coastal segments. This enables dynamic risk based positioning of tugs, using both real-time and projected risk, for effective support in case of a drifting ship situation.  相似文献   
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Earth-reservoirs are increasingly exploited today with the extraction of resources, such as heat and hydrocarbons, and the large-scale emplacement of waste, such as CO2 sequestration. The characterization, site investigation, predictive modeling and long-term monitoring are dependent on the processes being investigated and modeled. In most cases complex coupled processes have to be addressed in a geologically complex rock mass system. In this paper we present a conceptual holistic framework known as geomechanical facies linking all the scales of investigation, characterization and reservoir development methods. We demonstrate this concept on the work undertaken during the design and development of the enhanced geothermal systems (EGS) systems at the forefront of European Hot-Dry-Rock (HDR) technology, Soultz-sous-Forêts (France) and Spa Urach (Germany). Soultz-sous-Forêts is situated within granitic rocks and an active tectonic graben system in the central part of the Rhine Graben. It presents conditions of lithology, temperature, stress, hydraulics and geochemistry that are very different from those at Spa Urach, located in a very dense gneiss formation in the South German crystalline complex. Spa Urach exhibits more elastic behavior and is set tectonically within an almost inactive strike-slip stress field described in more detail in Sects. “Drill core analysis” and “Hydraulic stimulation at Spa Urach”. This paper compares the exploration and field development methods used at these two sites against the back drop of the geomechanical facies concept. Issues addressed include the key parameters for flow and heat transport properties, coupled hydro-mechanical process identification, the success of the HDR reservoir as a heat exchanger and exploration techniques applicable to the different facies. Identification of the key geomechanical facies gives an indication as to which technologies will prove more efficient in the application of HDR technology. The results of this study will hopefully help in developing heat recovery schemes for the long-term economical operation of future HDR plants and EGS as well as assist in the understanding of engineered geosystems.  相似文献   
47.
The structural evolution of a part of the late Precambrian Baltoscandian passive margin just before the inception of seafloor spreading is described, recording the change from deformation by faulting to dominantly magmatic extension of the crust. The allochthon of the Scandinavian Caledonides contains the imbricated passive margin of continental Baltica overlain by various exotic terranes. The Sarektjåkkå Nappe in the Seve Nappe Complex, which contains the outer parts of Baltica's passive margin, consists of sedimentary rocks, occurring as screens between Vendian (573±74 Ma) diabase dykes. These dykes constitute 70–80% of the nappe and locally form sheeted dyke complexes. The Sarektjåkkå Nappe largely escaped penetrative Caledonian deformation and preserves igneous, metamorphic and structural elements that are linked to the evolution of a pre-Caledonian rift to a passive continental margin. Extensional deformation before dyke emplacement is recorded by normal faults, pull-apart structures and folds. Unconformities, dykes affected by brittle deformation, and fluidization of sediments during dyke emplacement indicate close relations between the deposition of sediments, extensional deformation and dyke emplacement. The Sarektjåkkå Nappe is compared with other parts of the Baltica's passive margin and its tectonic evolution is discussed.  相似文献   
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To obtain data on heavy metal contaminated soil requires laborious and time-consuming data sampling and analysis. Not only has the contamination to be measured, but also additional data characterizing the soil and the boundary conditions of the site, such as pH, land use, and soil fertility. For an integrative approach, combining the analysis of spatial distribution, and of factors influencing the contamination, and its treatment, the Mollifier interpolation was used, which is a non-parametric kernel density regression. The Mollifier was capable of including additional independent variables (beyond the spatial dimensions x and y) in the spatial interpolation and hence explored the combined influence of spatial and other variables, such as land use, on the heavy metal distribution. The Mollifier could also represent the interdependence between different heavy metal concentrations and additional site characteristics. Although the uncertainty measure supplied by the Mollifier at first seems somewhat unusual, it is a valuable feature and supplements the geostatistical uncertainty assessment.  相似文献   
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