Sediment dynamics in the Castleton karst,Derbyshire, U.K.     

Simon Bottrell  Paul Hardwick  John Gunn 《地球表面变化过程与地形》1999,24(8):745-759

Chemical and mineralogical data are presented for a suite of 59 sediment samples collected from the P8 and Speedwell cave systems (and mineralogical data are presented for a further six surface sediments) in the Castleton karst catchment, Derbyshire, England. Sediments are grouped according to age and depositional environment and these groups show distinctive mineralogical and chemical characteristics. Clay mineralogy is effective at distinguishing different sediment sources for ancient and modern sediments which are derived from pre-Devensian tills and Devensian solifluction deposits, respectively. Major element chemistry reflects these differences in clay mineral content, while trace elements demonstrate the importance of abrasion of ore minerals in conduits in the aquifer which follow mineral veins, even under natural, pre-mining conditions. Clay minerals are confirmed as the host for uranium in uranium-rich ancient sediments. Consideration of organic carbon and hydrogen concentrations shows that plant material is the dominant source of organic material in the modern sediments. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Cycle mechanism in accretion disk regions near a Kerr hole     

H. G. Paul 《Astronomische Nachrichten》1990,311(3):205-205

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Sources of uncertainty in the NRCS CN model: Recognition and solutions          下载免费PDF全文

Pablo Durán‐Barroso  Javier González  Juan B. Valdés 《水文研究》2017,31(22):3898-3906

The Natural Resources Conservation Service Curve Number model is one of the most recognizable procedures in the field of rainfall–run‐off estimation. It has been widely applied for different purposes in hydrological models. In spite of its widespread use, some uncertainties have not even clarified and must be examined for its proper application. Particularly, choosing the most representative rainfall–run‐off events, and the coefficient λ that relates the parameters of the model (curve number CN and initial abstraction I_a). In this research, an advanced analysis is developed to evaluate the influence of λ for a set of representative watersheds of the Agricultural Research Service of the United Stated Department of Agriculture. They are characterized by different soil properties, land uses, and climatic conditions. Finally, 2 novel methodologies for the selection of the most representative rainfall–run‐off events and for the adaptation of coefficient λ are included, based on the pattern of rainfall distribution.  相似文献   

Patterns in the linkage of water quantity and quality during low‐flows          下载免费PDF全文

Jost Hellwig  Kerstin Stahl  Jens Lange 《水文研究》2017,31(23):4195-4205

This study investigates 72 catchments across the federal state of Baden‐Wuerttemberg, Germany, for changes in water quality during low‐flow events. Data from the state's water quality monitoring network provided seven water quality parameters (water temperature, electrical conductivity, concentrations of chloride, sodium, sulfate, nitrate, and phosphate), which were statistically related to streamflow variability. Water temperature changes during low‐flow showed seasonal dependence. Nitrate concentrations revealed high spatial heterogeneity with about one third of the stations showing decreasing values during low discharge. For most other parameters, concentrations increased during low‐flow. Despite consistent trend directions, the magnitudes of changes with streamflow differed markedly across the state. Both multiple linear regression and a multiple analysis of variances were applied to explain these differences with the help of catchment characteristics. Results indicated that for sulfate and conductivity, geology of the catchments was the most important control, whereas for chloride, sodium, and nitrate, sewage treatment plants had the largest influence. For phosphate, no clear control could be identified. Independent from the applied method, land use was a less important control on river water quality during low‐flow than geology or inflow from sewage treatment plants. These results show that the effects of diffuse and point sources, as well as those of natural and anthropogenic sources differ for different water quality parameters. Overall, a high diversity of potential water quality deterioration signals needs to be considered when the ecological status of rivers is to be protected during low‐flow events.  相似文献   

Optical identification of the source IGR J08390-4833 from the INTEGRAL all-sky survey     

M. G. Revnivtsev  A. Yu. Kniazev  S. Yu. Sazonov  R. A. Burenin  A. Tekola  D. A. H. Buckley  M. L. Pretorius  J. Menzies  W. Lawson 《Astronomy Letters》2009,35(1):33-38

Results of the optical identification of the hard X-ray source IGR J08390-4833 recently discovered in the INTEGRAL all-sky survey are presented. We show that the source is most likely a cataclysmic variable, i.e., an accreting white dwarf in a binary. Analysis of its optical light curve clearly reveals intrinsic variability on timescales of the order of an hour or longer. However, the short time of the source’s optical observations does not allow a definitive conclusion about the periodicity of the detected variability to be reached. Further optical and X-ray observations are required for a more accurate classification of the source.  相似文献   

气提工艺在原油稳定装置中的应用研究   总被引：2，自引：0，他引：2  

王念兵  宋丹 《中国勘察设计》2009,(3):49-52

原油稳定工艺是国内各大油田普遍实施的降低油气蒸发损耗、实现油气密闭集输、提高轻烃收率的重要措施。本课题结合中原油田原油稳定装置运行现状及存在的问题,进行了气提工艺在原油稳定装置中的技术改造和应用研究,以降低装置运行费用,提高轻烃回收率,使中原油田的原油稳定工艺达到一个新的水平。  相似文献   

松辽盆地徐深1井气藏气源的氢、碳同位素特征          下载免费PDF全文

薛海涛  刘海英  卢双舫  霍秋立  徐庆霞  李吉君 《地质科学》2009,44(2):635-644

选取松辽盆地内泥岩样品和煤样进行热模拟实验,建屯了两个样品成甲烷的氢、碳同位素分馏动力学模型并标定了动力学参数.分别以徐深1井区、沉降中心地质资料为例进行研究,表明两处源岩均有短期内大量生气的特点,气源岩生气期分别为距今95.5～73 Ma和距今0～73 Ma.计算得到两处源岩沙河子组暗色泥岩和煤、火石岭组暗色泥岩和煤所生天然气单独运聚成藏（自开始生烃到现今累积成藏）所对应的δ_DCH4 和δ¹³C₁,进而定量计算出徐深1井区源岩所生甲烷的δ_DCH4 为-237.3‰,δ¹³C₁为-28.8‰,沉降中心气源岩所生甲烷的δ_DCH4 为-2.5‰,δ¹³C₁为-24.8‰.以各区域天然气混合后的δ_DCH4 作为来源气体的端元同位素值,根据物质平衡原理计算得到：徐深1井区源岩对该区气藏的贡献比例约占72%,沉降中心源岩的贡献比例约为28%.同理以δ¹³C₁.方法得到徐深1井区源岩对该区气藏的贡献比例约占66%,沉降中心源岩的贡献比例约为34%.氢、碳同位素分馏的化学动力学地质应用结果存在的差异与同位素分馏模型标定所用热模拟实验为不加水实验有关.  相似文献   

含自相容源的可积系统     

李琪 《华东地质学院学报》2009,32(1):93-96

含自相容源的可积方程（SESCSs）是一类重要的非线性偏微分方程,研究其可积性和寻求其精确解都具有重要的数学意义,SESCSs描述的是不同孤波间的相互作用,又有重要的物理意义。这类方程也正丰富了Lax可积系统的内容。从可积意义上详细介绍了含自相容源的可积方程,与求解此类方程有关的构造含自相容源的可积方程的方法。给出Lax可积的概念,作为例子,给出了含自相容源的非等谱KdV方程族、含自相容源的非等谱AKNS方程族及其Lax表示。  相似文献   

河南熊耳山地区金矿的控矿因素分析   总被引：2，自引：1，他引：1  

李连涛  徐公权  王爱枝 《矿产与地质》2009,23(2)

熊耳山地区金矿的成矿物质来源主要来自基底太华群中深成变质岩、燕山期钙碱性岩浆岩以及构造蚀变岩。矿床受燕山期岩浆岩和构造控制明显,不同级别的构造控制着金矿的规模和展布。控矿断裂具有明显的方向性,断裂交汇处及断面产状变化处控制矿体或富矿体产出。文章从花岗岩特征和构造的控矿作用方面总结该区金矿的成矿规律,以期为进一步找矿提供借鉴。  相似文献   

Models-3模式中增加移动源清单对模拟效果的影响   总被引：1，自引：0，他引：1       下载免费PDF全文

王扬锋  马雁军  侯波  李炳昆  刘凤辉  任万辉 《气象与环境学报》2009,25(6):18-22

采用空气质量模式Models-3,在原有点源和面源污染源输入清单的基础上,加入移动污染源,对辽宁地区2004年12月24—27日大气污染物时空分布进行数值模拟。结果表明,加入移动污染源后,辽宁主要城市污染物SO₂、NO₂和PM₁₀模拟效果有所提高,NO₂模拟效果提高最为明显;从总体模拟效果来看, SO₂和NO₂模拟效果较好,而PM₁₀模拟值相对较差。  相似文献