Erratum to: Mission design,operation and exploitation of the Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission     

Rune?FloberghagenEmail author  Michael?Fehringer  Daniel?Lamarre  Danilo?Muzi  Bj?rn?Frommknecht  Christoph?Steiger  Juan?Pi?eiro  Andrea?da?Costa 《Journal of Geodesy》2012,86(3):241-241

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Sediment transport at the network scale and its link to channel morphology in the braided Vjosa River system     

Simone Bizzi  Marco Tangi  Rafael J. P. Schmitt  John Pitlick  Hervé Piégay  Andrea Francesco Castelletti 《地球表面变化过程与地形》2021,46(14):2946-2962

In this article we apply the CASCADE network-scale sediment connectivity model to the Vjosa River in Albania. The Vjosa is one of the last unimpaired braided rivers in Europe and, at the same time, a data scarce environment, which limits our ability to model how this pristine river might respond to future human disturbance. To initialize the model, we use remotely sensed data and modeled hydrology from a regional model. We perform a reach-by-reach optimization of surface grain size distribution (GSD) and bedload transport capacity to ensure equilibrium conditions throughout the network. In order to account for the various sources of uncertainty in the calculation of transport capacity, we performed a global sensitivity analysis. The modeled GSD distributions generated by the sensitivity analysis generally match the six GSDs measured at different locations within the network. The modeled bedload sediment fluxes increase systematically downstream, and annual fluxes at the outlet of the Vjosa are well within an order of magnitude of fluxes derived from previous estimates of the annual suspended sediment load. We then use the modeled sediment fluxes as input to a set of theoretically derived functions that successfully discriminate between multi-thread and single-thread channel patterns. This finding provides additional validation of the model results by showing a clear connection between modeled sediment concentrations and observed river morphology. Finally, we observe that a reduction in sediment flux of about 50% (e.g., due to dams) would likely cause existing braided reaches to shift toward single thread morphology. The proposed method is widely applicable and opens a new avenue for application of network-scale sediment models that aid in the exploration of river stability to changes in water and sediment fluxes.  相似文献   

绝对重力仪激光器光纤对准调节方法概述     

任敏拴  商永杰  郑文科  康胜军  赵丕 《大地测量与地球动力学》2020,40(9):981-984

绝对重力仪激光器光纤由于应力变化、形状改变、震动或耦合器维护等原因破坏了输出激光的偏振态,使其在光纤内的传输变得非常不稳定,导致光纤输出激光的消光比值小于100,无法满足绝对重力观测条件。针对该问题,介绍了光纤对准调节的方法,通过设计消光比检测装置检验消光比值是否大于100。对#181和#250两台WEO100型He-Ne激光器的光纤进行对准调节实验,并通过消光比检测装置实测,两台激光器输出的光束消光比值满足绝对重力测量的条件,表明该对准调节方法科学有效。  相似文献   

Assessment of a new solution for tracking pebbles in rivers based on active RFID          下载免费PDF全文

Mathieu Cassel  Thomas Dépret  Hervé Piégay 《地球表面变化过程与地形》2017,42(13):1938-1951

Low‐frequency passive integrated transponders (PIT tags), are commonly used for monitoring pebble mobility in gravel‐bed rivers. Although early studies reported high recovery rates for PIT tags used in small streams, recovery rates in larger systems remain low, substantially limiting the possibilities for their use in such rivers. These low recovery rates are potentially due to missed detections caused by tag signal collision, burial in the sediment layer deeper than the maximum detection range and insufficient (but still exhausting) field effort to cover the concerned areas. A potential solution for addressing these problems is to use active ultra‐high frequency (a‐UHF) transponders as these have a greater detection range and anti‐collision protocols. In order to assess the potential of such transponders for pebble tracking in rivers, we used 433.92 MHz COIN‐ID and COIN‐HC models (ELA Innovation Company, Montpellier, France). We completed several tests to (i) characterize transponder detection ranges in the water and in saturated sediment and (ii) develop field protocols for locating tags by combining global positioning systems (GPS) sites and transponder received signal strength indication (RSSI) levels. The results showed that (i) the maximum detection ranges are about 2.4 m in the water column and more than 2.6 m in a column of saturated gravelly‐sandy sediment, (ii) RSSI spatial interpolation can be used to determine transponder position with good accuracy (< 1 m), (iii) the desired minimal level of accuracy can be adjusted depending on in‐field effort and signal impulse interval, (iv) the RSSI maximal value observed cannot yet be used to determine transponder burial depth because of the multipath propagation of radio frequencies and the semi‐directional emission of the tag signal. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Multidimensional Toxicity of Rhamnolipid Extracts Obtained From Creosote‐Contaminated Soil          下载免费PDF全文

Zuzanna Sydow  Piotr Lisiecki  Justyna Staninska‐Pięta  Anna Olejnik  Paweł Cyplik  Agnieszka Zgoła‐Grześkowiak  Roman Marecik  Jacek Nowak  Katarzyna Glazar  Agnieszka Piotrowska‐Cyplik 《洁净——土壤、空气、水》2018,46(5)

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文昌B凹陷差异伸展- 走滑机制及控藏作用研究     

江汝锋  周家雄  杨希冰  游君君  李珊珊  陈林  张霞 《地质学报》2020,94(8):2422-2432

为查明文昌B凹陷油气富集差异性的原因,基于断裂展布和形成期次、构造样式组合、构造演化和断层活动的差异等标志,建立了差异伸展- 走滑机制,识别出19洼为伸展- 强走滑、14洼为伸展- 中等走滑、30洼为伸展- 弱走滑。差异伸展- 走滑作用控制了优质烃源岩的展布和供烃方向,控制输导体系类型和运移动力,提供物源通道和改造储层,还控制了圈闭类型和力学性质。进一步深化了走滑增压理论,基于先存断裂形态、伸展应力场右旋演化和应变差异,建立了走滑增压圈闭识别方法,识别出S型增压、右行左阶增压、斜交型增压3种走滑增压构造。研究表明,文昌B凹陷的油气富集受伸展- 走滑构造背景、源- 运时空配置关系所控制,强—中等走滑变形、发育优质中深湖源岩的文昌19洼和14洼是油气富集区。该研究成果成功推动了文昌凹陷近期的多个勘探发现。  相似文献   

正循环机械回转钻孔灌注桩在卵石层中的应用     

皮跃进 《福建地质》2009,28(3):250-252

在粒径、密实度较大的卵石层采用正循环机械回转钻进行灌注桩施工,存在钻具类型、合理的泥浆比例和钻探工艺等问题。以西安绕城高速公路谢王立交桥桥桩基工程实践为例,探讨正循环机械回转钻孔灌注桩在卵石层施工工艺等问题。  相似文献   

Formation of iron plaque on mangrove roots receiving wastewater and its role in immobilization of wastewater-borne pollutants   总被引：2，自引：0，他引：2  

Pi N  Tam NF  Wong MH 《Marine pollution bulletin》2011,63(5-12):402-411

Iron (Fe) plaque formed on mangrove root increased with wastewater discharge, but the extent was species-specific. For Bruguiera gymnorrhiza, Fe plaque concentration was 0.80 mg g(-1) root d.wt at Day 0 and increased to 4.59, 6.84 and 7.52 mg g(-1) at Day 75 in the fresh water control (FW), synthetic wastewater with pollutant concentrations five times of municipal sewage (5SW) and double of 5SW (10SW) treatments, respectively; the respective increases in Excoecaria agallocha were from 0.70 to 2.37, 10.73 and 13.21 mg g(-1). For Acanthus ilicifolius, similar increase was found in 5SW, but all of the plants were dead in 10SW at Day 75. The concentrations of heavy metals and phosphorus immobilized were positively correlated with the amounts of Fe plaque formed, but the regression coefficients varied among species. The performance of mangrove plants in wastewater treatments was related to the Fe plaque formed and its immobilized wastewater-borne pollutants.  相似文献   

Comparative phylogeography of African rain forest trees: A review of genetic signatures of vegetation history in the Guineo-Congolian region     

Olivier J. Hardy  Céline Born  Katarina Budde  Kasso Daïnou  Gilles Dauby  Jérôme Duminil  Eben-Ezer B.K. Ewédjé  Céline Gomez  Myriam Heuertz  Guillaume K. Koffi  Andrew J. Lowe  Claire Micheneau  Dyana Ndiade-Bourobou  Rosalía Piñeiro  Valérie Poncet 《Comptes Rendus Geoscience》2013,345(7-8):284-296

The biogeographic history of the African rain forests has been contentious. Phylogeography, the study of the geographic distribution of genetic lineages within species, can highlight the signatures of historical events affecting the demography and distribution of species (i.e. population fragmentation or size changes, range expansion/contraction) and, thereby, the ecosystems they belong to. The accumulation of recent data for African rain forests now enables a first biogeographic synthesis for the region. In this review, we explain which phylogeographic patterns are expected under different scenarios of past demographic change, and we give an overview of the patterns detected in African rain forest trees to discuss whether they support alternative hypotheses regarding the history of the African rain forest cover. The major genetic discontinuities in the region support the role of refugia during climatic oscillations, though not necessarily following the classically proposed scenarios. We identify in particular a genetic split between the North and the South of the Lower Guinean region. Finally we provide some perspectives for future study.  相似文献   

东方1-1气田时移地震技术研究与应用     

谢玉洪  陈志宏  周家雄  李添才  刘薇薇 《华南地震》2009,(Z1):60-68

时移地震方法就是利用不同时间上地震响应的变化来监测油气藏的变化,通过对东方1-1气田岩石物理实验、时移地震资料处理和解释,最后提出了东方1-1气田下一步开发调整的建议。  相似文献