Topsoil delivery to Himalayan rivers: the importance of sampling time          下载免费PDF全文

M. Nawaz  R. J. Wasson  R. Bhushan  N. Juyal  F. Sattar 《水文研究》2016,30(24):4609-4616

Estimates of the amount of topsoil in river sediments can help constrain sediment budgets on decadal time scales. The tracers ¹³⁷Cs and ²¹⁰Pb(ex) are used to determine the proportion of topsoil in river sediments in two Himalayan catchments, a relatively simple but effective method that could be used in many catchments in this complex mountain range for management purposes. Different results are reached, apparently depending upon antecedent conditions, with a large component of topsoil in river sediments likely to be the result of rainfall that erodes hillslopes by sheet and rill processes, does not mobilize or mix with other sources of sediment such as from landslides, and does not generate high river flows to transport the topsoil downstream. These results show that sampling of tracers in sedimentary archives is essential to provide time series of topsoil input to Himalayan rivers to account for high temporal variability. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

豫西铝土矿中镓的赋存状态研究     

汤艳杰  刘建朝  贾建业 《地球科学与环境学报》2002,24(4):1-5

豫西地区的铝土矿中含有丰富的镓资源。由于对矿石中镓的赋存状态研究程度很低,使镓未能有效回收。通过对铝土矿石的扫描电镜观察、电子探针成分分析、X射线衍射分析,并且完成了在盐酸介质中浸取镓的条件实验,初步得出了元素镓在铝土矿石中的赋存形式主要为:以类质同象置换的形式存在于矿物晶格之中;部分以吸附的形式存在于粘土矿物微粒和铝、铁的氢氧化物表面。  相似文献   

Chalcopyrite Intergrowths in sphalerite in the Meixian Lead—Zine Deposit,Fujian Province and their Metallogenic Significance   总被引：2，自引：0，他引：2  

顾连兴  周兵等 《中国地球化学学报》1998,17(4):311-319

Ore textures and electron microprobe analyses show that in addition to highly scattered blebs in sphalerite grains,intergrown chalcopyrite also occurs as rods,myrmekites and lamellae aligned along cleavages and twin boundaries of the host sphalerite.The majority of the intergrowths could have been formed by replacement of sphalerite by chalcopyrite,albeit part of them may have resulted from exsolution,Not only copper,but also iron were introduced into the sphalerite by replacive fluids.While the front of the replacing fluid was moving forward through a sulphide orebody,Zn and Pb were dissolved and Cu was precipitated,resulting in zonal refining of the sulphide ores,The remobilized zinc and lead were precipitated at favourable sites with changed physico-chemical conditions .This is a possible mechanism for the formation of copper-poor zinc and lead ores above or lateral to the copper orebodies in some of the massive sulphide deposits reworked and overprinted by late-stage granites and their hydrothermal fluids.  相似文献   

水泥土搅拌桩复合地基的优化设计     

连长江  张孝华 《上海国土资源》1998,(4):33-37

运用双层地基模型的线弹性有限元程序对不同类型水泥土搅拌桩复合地基的沉降进行计算,分析了水泥土搅拌桩的桩长、置换率、桩身刚度对地基沉降的影响,同此确定了搅拌桩的有效桩长、最优置换率、最优桩身刚度。  相似文献   

南京地区土壤元素的人为活动环境富集系数研究   总被引：27，自引：9，他引：18       下载免费PDF全文

廖启林 金 洋吴新民  毕葵森范迪富 华 明 《中国地质》2005,32(1):141-147

南京周边地区开展多目标地球化学调查获取了“双层土壤”各元素的含量,表层土壤的元素含量与其深层土壤元素含量之比值即称之为土壤中该元素的人为话动环境富集系数(简称环境富集系数),笔者介绍了有关环境富集系数的计算方法。通过对比研究区各元素环境富集系数分布特征,发现本区表层土壤中Si、Ti、La、Ce、Y、Sc、Zr、Th、U、W等元素与其自然土壤环境的含量相近,S、N、P、Hg、Pb、Cl、Br、Se等元素及有机碳呈现了显著的人为环境富集,I、Fe、Mg、Mn、Ca、Al、K等元素出现了地表贫化。最后探讨了深入开展土壤中元素环境富集系数研究的相关问题,并提出了建议。  相似文献   

The Truncated Discovery Process Model     

Kenneth?G.?LoganEmail author 《Natural Resources Research》2005,14(3):265-281

The purpose of this paper is to describe a mathematical and computer model that has been developed by TransCanada for TransCanada Pipelines (TCPL) and for the Canadian Gas Potential Committee (CGPC) for future Canadian natural gas resource assessment work. It was developed in the contexts of developing a gas supply model for forecasting future Canadian gas supply for TCPL and of improving the CGPC's assessment methodologies and software. The model developed in this paper integrates two discovery process models used by the CGPC and solves the economic truncation problem for semi-mature to mature plays. It is based on applying techniques developed by G. M. Kaufman and J. D. Fuller and colleagues in new ways which extends the work of these authors. This model has a number of important advantages including: fast computational speed, integration of parametric and nonparametric statistical approaches, integration of the Kaufman and others model and the Arps-Roberts model, overcoming a PETRIMES limitation of a maximum of 1000 samples, providing a finding rate forecast for economic analysis and providing a fresh look at solving the economic truncation problem. The details of the new Modified Arps-Roberts Model (now known as the Truncated Discovery Process Model or TDPM for short) are discussed in this paper.  相似文献   

Global retail capital and the city: towards an intensification of gentrification     

Anne-Cécile Mermet 《Urban geography》2017,38(8):1158-1181

The emerging literature on retail gentrification has not paid much attention to the link between recent reconfigurations of retail capital (concentration, internationalization, and financialization) and the contemporary wave of “generalized gentrification”. In this paper, I argue that analyzing the strategies of stakeholders involved in sectors other than housing (in this case, the retail sector) should allow us to identify different forms of gentrification intensification. I investigate the case of the Marais – that is, one of the first Parisian neighborhoods having undergone gentrification – by mapping the frontier of retail gentrification over the long term (1965–2011) and at the scale of an entire neighborhood (more than 130 ha comprising over 2,000 commercial units). The key drivers of the process (commercial real estate, new brand development strategies, changing commercial environment, the role of public policies) and its social stakes (displacement/replacement of former stores) are then discussed.  相似文献   

Seabed Ground Improvement in Coastal Reclamation Area by Heavy Tamping After Rockfilling Displacement     

Yu-Chun Cao  Wei-Tang Wang 《Marine Georesources & Geotechnology》2007,25(1):1-14

Considering the characteristics of seabed ground in coastal reclamation area, ultra soft clay improvement method by heavy tamping after rockfilling displacement was proposed combined with a case study. The improvement mechanisms of the method can primarily be attributed to rockfilling displacement (RD), dynamic compaction (DC), dynamic replacement (DR) and dynamic replacement and mixing (DRM). For the case study given in this article, heavy tamping construction program was proposed based on field pilot tests. Furthermore, the effectiveness of the proposed ground improvement method was verified through in situ plate load test, sand fill test and the analyses of observed settlement data. Thus, the method of heavy tamping after rockfilling displacement is applicable for the improvement of seabed ground in coastal reclamation area. It is proposed for similar projects that heavy tamping of fills may be performed by layers and correspondingly tamping energy increased to further enhance the improvement effect of DC, DR and DRM. In addition, delayed improvement effect or time effect of soil mass after heavy tamping is still an issue to be further studied.  相似文献   

船舶压载水中有害生物的管理与控制   总被引：7，自引：0，他引：7  

李迪阳  姜仕倩  王俊英 《海岸工程》2001,20(3):47-53

对由压载水引起的外来生物污染问题进行了较详细的分析。介绍了目前已经应用或正处于研究中的各种对压载水处理方法 ,探讨了其优越性及发展前景  相似文献   

Ecosystem service values of sediment generation and entrapment by marginal coral reefs at Sodwana Bay,South Africa     

SCS Laing  MH Schleyer  JK Turpie 《African Journal of Marine Science》2020,42(2):199-207

Coral reefs provide a multitude of goods and services, some of which are difficult to value due to their intangible nature and the absence of markets to ascribe their relative worth. The coral reefs of Sodwana Bay on the northeast coast of South Africa provide several ecological goods and services, of which only two are considered here: namely, sediment generation and sediment entrapment. Both are deemed essential to the functioning of the Sodwana Bay economy. The replacement-cost method was used to estimate the annual financial cost of sediment provided to the study area if it were replaced by dredging. Sediment generation by the coral reefs was valued at R2.6–R4.8 million, and sediment entrapment valued at R71.8–R84.6 million, totalling between R74.4 million and R89.4 million (≈$5.6–$6.7 million, at R13.38/US$1) per year.  相似文献