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排序方式: 共有99条查询结果,搜索用时 15 毫秒
71.
D. M. Kargbo 《Environmental Geology》1994,23(2):105-113
About 70 percent of hazardous waste sites listed in the National Priority List (NPL) have some groundwater contamination that may require remediation. Such remediation is inadequate if the unsaturated soils above will continue to act as a source of groundwater contamination. Consequently, for most of these sites, it becomes necessary to determine what the cleanup levels for contaminants in soils should be so that subsequent contribution of contaminants from these soils to groundwater would not exceed groundwater protection levels. Representation of the dynamics of interactions between contaminants and soils is very complex, requiring among others, a thorough understanding of the chemical processes that influence the behavior of the contaminant once it enters the subsurface. Because of such complexities, environmental professionals frequently utilize methods with very simple assumptions that tend to err on the conservative side. While the public may feel protected, the needless spending of dollars could be avoided if attempts are made to incorporate, where possible, such complexities in the modeling efforts so that the system is represented as accurately as possible. 相似文献
72.
Lawrence J. B. Orikiriza Hillary Agaba Mnason Tweheyo Gerald Eilu John David Kabasa Aloys Hüttermann 《洁净——土壤、空气、水》2009,37(8):615-620
The classical aim of the application of super absorbent polyacrylate (SAPs) hydrogels is the prolonging of plant survival under water stress. Their effect on plant growth during non‐water stress conditions is not known. This study examined the root and shoot biomass of seedlings of nine tree species; Eucalyptus grandis, Eucalyptus citriodora, Pinus caribaea, Araucaria cunninghamii, Melia volkensii, Grevillea robusta, Azadirachta indica, Maesopsis eminii and Terminalia superba. The seedlings were potted in five soil types; sand, sandy loam, loam, silt loam and clay. These were amended at two hydrogel levels: 0.2 and 0.4% w/w and grown under controlled conditions in a green house. Root and shoot growth responses of the seedlings were determined by measuring the dry weight of the roots, stems, leaves and twigs. The addition of either 0.2 or 0.4% hydrogel to the five soil types resulted in a significant increase of the root dry weight (p < 0.001) in eight tree species compared to the controls after 8 wk of routine watering. Also, the dry weight of stems and leaves and twigs were significantly (p < 0.001) higher in the nine tree species potted in hydrogel amended soil types than in the hydrogel free controls. These results suggested that hydrogel amendment enhances the efficiency of water uptake and utilization of photosynthates of plants grown in soils which have water contents close to field capacity. 相似文献
73.
开挖过程的非线性理论分析 总被引:19,自引:3,他引:16
本文从岩土介质力学非线性和变形破坏过程自组织非线性的角度对开挖过程岩土体非线性行为进行了探讨。以此为依据,分析了岩土从微观破坏、滑移面形成、直至整体变形破坏全过程的自组织发生机理,在此基础上,建立了伴随开挖过程岩土体变形破坏的非线性动力学描述方程。 相似文献
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张广才岭成矿带铁力-玉泉有色金属、贵金属矿带成矿特征分析 总被引:2,自引:0,他引:2
论述了张广才岭成矿带铁力-玉泉有色金属、贵金属矿带中的各类矿床与燕山早期、中期及印支晚期岩浆侵入作用的成因关系,指出侵入岩的控矿作用。并分析成矿特征与成矿规律,指出了找矿方向。 相似文献
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吉林省农业界限温度条件变化规律研究 总被引:9,自引:3,他引:6
用线性回归,相对变率,非整数波及小波周期分析等方法,分析了自有气象记录以来,吉林省不同区域日平均气温稳定≥7℃初日,终日、≥10℃积温及5 ̄9月平均气温之和等几项与农业生产有密切关系的界线温度条件的长期变化特征,揭示了它们的时间变化趋势和周期变化规律,探讨了未来10a内这些条件的可能变化趋势及农业生产问题。 相似文献
78.
黄山第四纪泥砾沉积物分形结构特征与沉积环境分析 总被引:13,自引:0,他引:13
黄山第四纪泥砾沉积物粒度组成的分维值介于2.708 ̄2.753之间,非常接近古泥石流堆积物粒度组成的典型分维值2.75。结合沉积特征,表明该类沉积物属第四纪间冰缘环境下的稀性泥石流沉积,其形成过程与季风型冰缘环境有关,是两种环境综合作用的结果。 相似文献
79.
Geostatistical seismic inversion for non‐stationary patterns using direct sequential simulation and co‐simulation
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Hamid Sabeti Ali Moradzadeh Faramarz Doulati Ardejani Leonardo Azevedo Amilcar Soares Pedro Pereira Ruben Nunes 《Geophysical Prospecting》2017,65(Z1):25-48
Geostatistical seismic inversion methods are routinely used in reservoir characterisation studies because of their potential to infer the spatial distribution of the petro‐elastic properties of interest (e.g., density, elastic, and acoustic impedance) along with the associated spatial uncertainty. Within the geostatistical seismic inversion framework, the retrieved inverse elastic models are conditioned by a global probability distribution function and a global spatial continuity model as estimated from the available well‐log data for the entire inversion grid. However, the spatial distribution of the real subsurface elastic properties is complex, heterogeneous, and, in many cases, non‐stationary since they directly depend on the subsurface geology, i.e., the spatial distribution of the facies of interest. In these complex geological settings, the application of a single distribution function and a spatial continuity model is not enough to properly model the natural variability of the elastic properties of interest. In this study, we propose a three‐dimensional geostatistical inversion technique that is able to incorporate the reservoir's heterogeneities. This method uses a traditional geostatistical seismic inversion conditioned by local multi‐distribution functions and spatial continuity models under non‐stationary conditions. The procedure of the proposed methodology is based on a zonation criterion along the vertical direction of the reservoir grid. Each zone can be defined by conventional seismic interpretation, with the identification of the main seismic units and significant variations of seismic amplitudes. The proposed method was applied to a highly non‐stationary synthetic seismic dataset with different levels of noise. The results of this work clearly show the advantages of the proposed method against conventional geostatistical seismic inversion procedures. It is important to highlight the impact of this technique in terms of higher convergence between real and inverted reflection seismic data and the more realistic approximation towards the real subsurface geology comparing with traditional techniques. 相似文献
80.