河流渗滤系统对地表污水的净化作用综述   总被引：5，自引：1，他引：5  

李金荣  杨振放 《水文地质工程地质》2006,33(3):41-44

河流渗滤系统可充分利用水环境的净化功能,提高污水处理效率,避免地下水遭受污染.河流渗滤对地表污水的净化是一种自然过程,它作为天然的过滤器及生物地球化学反应器,可以除去河水中多种污染物,包括天然有机物、合成有机物、无机物、颗粒物、细菌及病原体等.文章分析了影响河流渗滤系统自净作用的影响因素,包括河流沉积物的组成、河流渗滤系统的结构、季节等.最后提出了今后研究河流渗滤系统的方向.  相似文献   

河流渗滤系统对硝态氮污水的净化作用研究     

李金荣  李金玲  杨振放 《水文地质工程地质》2007,34(1):24-28,43

河流渗滤系统对入渗的地表水有一定的净化作用,过去人们很少从理论上研究河流渗滤系统对污染河水的净化作用。本文采用室内土柱实验装置来模拟渭河渗滤系统,研究了硝态氮污染的河水在该系统中的环境行为及净化机制,其环境行为主要为反硝化作用。其净化程度与该渗滤系统的渗滤介质有关,如果渗滤介质为粘土,其净化率达到100%。若介质为粗砂粒物质,其净化程度较低。  相似文献   

纳米材料对低固相冲洗液性能影响的研究          下载免费PDF全文

刘徐三 《探矿工程》2022,49(4):61-67

低固相冲洗液是最适合绳索取心钻探工艺的冲洗液类型之一,但其防塌护壁能力和钻孔净化能力弱,阻碍了绳索取心钻探工艺在复杂地层的应用。本文通过实验研究,分析了纳米四氧化三铁、纳米氮化硼、纳米二氧化钛、多壁碳纳米管和纳米二氧化硅对低固相冲洗液的流变性能和滤失性能的影响规律。结果表明：纳米四氧化三铁、多壁碳纳米管和纳米氮化硼对低固相冲洗液的性能影响最明显,且具有增粘提切的作用。在此基础之上,通过正交实验分析了上述3种纳米材料复合后对低固相冲洗液性能的影响规律,得到性能优良的复合纳米低固相冲洗液体系优化配方：3%钠基膨润土+0.5%CMC-HV+0.3%纳米四氧化三铁+0.9%纳米氮化硼+0.9%多壁碳纳米管。最后,分析了纳米材料改善低固相冲洗液性能的作用机理。  相似文献   

Seasonal and spatial distribution of redox zones during lake bank filtration in Berlin,Germany   总被引：4，自引：0，他引：4  

Gudrun Massmann  Alexander Nogeitzig  Thomas Taute  Asaf Pekdeger 《Environmental Geology》2008,54(1):53-65

Redox processes during bank filtration were evaluated in Berlin, where bank filtered water is abstracted for drinking water production. The investigations included the mapping of the infiltration zone, a column study and hydrochemical analyses of the groundwater sampled between lake and production well. The organic carbon content increased and the permeability of the lake sediments decreased with distance from the shoreline. The most important changes with regard to the redox state of the infiltrate occurred within the first metre of flow. Infiltration was mostly anoxic, as oxygen was rapidly consumed within the organic rich sediments. The infiltration zone revealed a vertical redox stratification with hydrochemical conditions becoming more reducing with depth rather than with distance from the lake. The redox zones were found to be very narrow below the lake and wider towards the production wells, suggesting that other than differing flow paths, reaeration after infiltration may also occur and possible mechanisms are presented. Redox conditions were influenced by strong annual temperature variations of the surface water affecting the microbial activity. Aerobic infiltration only took place close to the shore in winter.  相似文献   

一种改进的LiDAR点云TIN迭代滤波算法     

徐国杰  胡文涛 《测绘信息与工程》2010,35(1):33-35

采用了设定最大内插距离和最大内插角度两个阌值,根据滤波次数动态调整了其值以达到最佳滤波效果,实现并改进了TIN迭代滤波算法。  相似文献   

The poorest and most vulnerable? On hazards,livelihoods and labelling of riverine communities in Bangladesh     

Haakon Lein 《Singapore journal of tropical geography》2009,30(1):98-113

Within the field of hazard research, vulnerability studies have been central to inducing a shift in the perspective on disasters as being primarily inflicted by geophysical events to that of apprehending disasters as destructive outcomes of particular social as well as hazardous environmental conditions. However, the inherent tendency within vulnerability studies to classify certain areas or people as 'vulnerable' may in some cases also serve to reinforce popular and/or ingrained prejudices, negative stereotypes and dubious explanations of the living conditions and fate of specific communities that become so labelled. The riverbanks and islands in river courses of Bangladesh have long been portrayed as home to the 'poorest' and most vulnerable communities, the widespread assumption being that people would only live in such riverine environments because they have no other options. Drawing on an examination of existing literature on char settlements in Bangladesh and data from a field site in the Jamuna River, this paper argues that the prevailing perceptions and labelling of char dwellers as 'vulnerable' people is based on a far too simplistic understanding of both rural migration patterns and the livelihoods obtained in these riverine areas.  相似文献   

Monitoring and numerical modelling of riverbank erosion processes: a case study along the Cecina River (central Italy)   总被引：2，自引：0，他引：2  

Laura Luppi  Massimo Rinaldi  Liliana B. Teruggi  Stephen E. Darby  Laura Nardi 《地球表面变化过程与地形》2009,34(4):530-546

Riverbank retreat along a bend of the Cecina River, Tuscany (central Italy) was monitored across a near annual cycle (autumn 2003 to summer 2004) with the aim of better understanding the factors influencing bank changes and processes at a seasonal scale. Seven flow events occurred during the period of investigation, with the largest having an estimated return period of about 1·5 years. Bank simulations were performed by linking hydrodynamic, fluvial erosion, groundwater flow and bank stability models, for the seven flow events, which are representative of the typical range of hydrographs that normally occur during an annual cycle. The simulations allowed identification of (i) the time of onset and cessation of mass failure and fluvial erosion episodes, (ii) the contributions to total bank retreat made by specific fluvial erosion and mass‐wasting processes, and (iii) the causes of retreat. The results show that the occurrence of bank erosion processes (fluvial erosion, slide failure, cantilever failure) and their relative dominance differ significantly for each event, depending on seasonal hydrological conditions and initial bank geometry. Due to the specific planimetric configuration of the study bend, which steers the core of high velocity fluid away from the bank at higher flow discharges, fluvial erosion tends to occur during particular phases of the hydrograph. As a result fluvial erosion is ineffective at higher peak discharges, and depends more on the duration of more moderate discharges. Slide failures appear to be closely related to the magnitude of peak river stages, typically occurring in close proximity to the peak phase (preferentially during the falling limb, but in some cases even before the peak), while cantilever failures more typically occur in the late phase of the flow hydrograph, when they may be induced by the cumulative effects of any fluvial erosion. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Size fractionation of phosphorus (dissolved, colloidal and particulate) in two tributaries to Lake Lugano     

Sabine Hilger  Laura Sigg  Alberto Barbieri 《Aquatic Sciences - Research Across Boundaries》1999,61(4):337-353

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Combined Effect of Climatic Variations and Groundwater Movement on Observed Heat Flow     

Parkhomov  M.D.  Zui  V.I. 《Studia Geophysica et Geodaetica》1999,43(3):265-274

In most practical situations, the upper part of a geological section consists of loose sediments, in which heat transfer cannot be described as a purely conductive process. To investigate such situations a one-dimensional numerical model of terrestrial temperature field formation under the combined influence of vertical groundwater filtration and ground surface temperature changes has been developed. The model allows one to consider the perturbation of heat flow interval values resulting from short- and long-period temperature waves propagating into permeable rocks under conditions of advective heat transfer, caused by vertical groundwater filtration. The results show that temperature profiles and interval heat flow values are sensitive to both the paleoclimatic history and the rate of groundwater filtration. The latter plays the prevailing role in the variations of geothermal field parameters, especially within the uppermost part of the loose sediments in unconfined aquifers. The problem was solved for a permeable layer, underlaid by an impermeable layer. This schematisation of water exchange is the typically accepted for hydrogeological analysis. Even at very low rates of filtration the intensity of this effect is enhanced substantially for long-period variations. In the extreme case (for periods of temperature variations of the order of 100,000 years) at typical rates of filtration within the permeable layer, an almost gradient-free zone can be formed down to depths of a few hundred metres. For the case of upward filtration, on the contrary, the influence of climatic variations on the terrestrial temperature field becomes substantially attenuated.  相似文献   

极限保土状态下的反滤机制试验研究   总被引：4，自引：3，他引：1  

陈轮  庄艳峰  许齐  王钊 《岩土力学》2008,29(6):1455-1460

提出了反滤系统极限保土状态的概念,分别采用4种不同孔径的钢丝编织网进行粉土反滤试验,研究反滤系统的极限保土状态。试验表明,当滤网孔径O和粉土特征粒径d85的比值等于12时,反滤系统才达到极限保土状态。极限保土状态下的反滤系统,在淹没式出流条件下,经往复水流作用26 h后改为单向水流,水力梯度从3.8逐渐增加到9.1,并在9.1的水力梯度下持续渗透453.25 h,反滤系统仍保持稳定,未发生失稳破坏;在非淹没式出流条件下,水力梯度从5.3逐渐增加到12.7期间,反滤系统保持稳定,但在维持12.7的水力梯度下持续渗透261.83 h后,反滤系统发生失稳破坏。对极限保土状态的研究有助于工程设计中更加合理地确定织物滤层孔径上限,减少淤堵。  相似文献