Remotely sensed rivers in the Anthropocene: state of the art and prospects     

Hervé Piégay  Fanny Arnaud  Barbara Belletti  Mélanie Bertrand  Simone Bizzi  Patrice Carbonneau  Simon Dufour  Frédéric Liébault  Virginia Ruiz-Villanueva  Louise Slater 《地球表面变化过程与地形》2020,45(1):157-188

The rivers of the world are undergoing accelerated change in the Anthropocene, and need to be managed at much broader spatial and temporal scales than before. Fluvial remote sensing now offers a technical and methodological framework that can be deployed to monitor the processes at work and to assess the trajectories of rivers in the Anthropocene. In this paper, we review research investigating past, present and future fluvial corridor conditions and processes using remote sensing and we consider emerging challenges facing fluvial and riparian research. We introduce a suite of remote sensing methods designed to diagnose river changes at reach to regional scales. We then focus on identification of channel patterns and acting processes from satellite, airborne or ground acquisitions. These techniques range from grain scales to landform scales, and from real time scales to inter-annual scales. We discuss how remote sensing data can now be coupled to catchment scale models that simulate sediment transfer within connected river networks. We also consider future opportunities in terms of datasets and other resources which are likely to impact river management and monitoring at the global scale. We conclude with a summary of challenges and prospects for remotely sensed rivers in the Anthropocene. © 2019 John Wiley & Sons, Ltd.  相似文献   

The source of raw materials for Roman pottery from Leptiminus,Tunisia     

Barbara L. Sherriff  Patricia Court  Shannon Johnston  Lea Stirling 《Geoarchaeology》2002,17(8):835-861

Leptiminus, a Roman port city on the west coast of Tunisia, North Africa, exported olive oil and a garum fish paste to Rome. Excavations have uncovered many facilities including kilns and a potter's workshop, indicating an extensive ceramic industry. The vessels, manufactured at Leptiminus, included African red‐slip fineware, coarseware, and amphorae. A petrographic study of pottery sherds showed them to contain very similar temper, rounded aeolian sand grains and limestone, but varying in proportions to produce different textures. An investigation of the source of raw materials for the pottery found three distinct types of clay within a 50 km radius of Leptiminus: grey Miocene, brown Pliocene, and green Late Pliocene clay. Statistical analysis of trace element compositions, using induced neutron activation, of clays and sherds showed that the Pliocene brown clay was used to create all types of pottery. The specific clay horizon, used in Roman times, has apparently been removed by quarrying. However, a lateral continuation of this bed was found 7 m beneath the Leptiminus site 290. © 2002 Wiley Periodicals, Inc.  相似文献   

Sampling Method for the Determination of Total Inorganic Carbon (TIC) in Strongly Acidic Waters     

Barbara Zippel  Helgard Tittel  Wolf von Tümpling jr. 《洁净——土壤、空气、水》2001,29(5):309-312

Samples from extremely acidic waters should be taken using the introduced syringe technique avoiding atmospheric contact to minimize CO2 evaporation from the samples. The syringe technique inclusive manual injection enables the determination of TIC in acid waters with high precision and accuracy. If a TOC analyser with a small sample volume is used, the vials should be filled directly inside the water sampler without air bubbles, covered with aluminium foil and transported at ambient water temperatures. If an autosampler is used, partial selection of the vials increases the stability of the results. Care should be taken that samples can be analysed within a short time.  相似文献   

Vertical accretion rates in fluvial systems: ­a comparison of volumetric and depth‐based estimates     

Barbara Rumsby 《地球表面变化过程与地形》2000,25(6):617-631

A wide range of approaches has been adopted for collecting and reporting vertical accretion rates, hence evaluation of results from different catchments, or even from different reaches within the same basin, is difficult as they may not be directly comparable. The present study compares depth‐ and volume‐based estimates of sediment accumulation for well‐dated vertical accretion sequences at Broomhaugh Island in the Tyne basin, northern England. High resolution dating control (based on heavy metal stratigraphy and cartography) coupled with detailed reconstruction of channel geometry allows accumulation rates to be calculated for the last 300–400 years. The results show a marked disparity in the magnitude and pattern of vertical accretion rates between the two approaches. The average annual thickness of sediment increases progressively, with a six‐fold difference between the seventeenth and twentieth centuries. The volume figures are more consistent, with a two‐fold difference between the highest and lowest rates, both of which occurred in the twentieth century. A major control on vertical accretion is found to be changing channel shape and capacity. Enlargement of the channel by 76 per cent since the seventeenth century, associated with channel bed incision, has resulted in fewer overbank flows. Hence floods, with their associated suspended sediment loads, which once inundated the floodplain are now confined within the channel. The reduced areal extent of surfaces available for deposition has resulted in greater annual thickness of sediment accumulated, despite an overall reduction in volume. This study emphasizes that caution is needed when attempting to identify causal linkages between changes in sedimentation rates and catchment land use and/or climatic factors and the geomorphological setting of the site must be taken into account. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Coral reef productivity and diversity—Contributions from enhanced photosynthesis via demand for carbohydrate from the host     

Melanie S. Adams  Barbara Demmig-Adams  Ruiqi Li  Daniel Zarate  Jingchun Li 《Marine Ecology》2020,41(6):e12618

Coral reefs’ high productivity has been attributed mainly to photosymbioses between the coral animal and algae of the family Symbiodiniaceae, with recognition that the host can increase algal photosynthesis by concentrating nutrients and enhancing the efficiency of light absorption. Here, we propose that an additional effect, consumption of carbohydrate by the host, may also enhance algal photosynthesis. We examine evidence from symbiosis between terrestrial plants and root fungi that indicates a link between carbohydrate consumption by the symbiotic partner and photosynthetic upregulation in the plant system. In addition, we review evidence from free-living algae manipulated to exude carbohydrate into the external medium, which was associated with strong upregulation of photosynthetic capacity. We offer suggestions on how host-induced carbohydrate release may increase photosynthesis rates in the symbionts in the intact photosymbiosis and how this relationship evolved.  相似文献   

Complementing the European earth observation and geographic information body of knowledge with a business‐oriented perspective     

Barbara Hofer  Sven Casteleyn  Estefanía Aguilar‐Moreno  Eva‐Maria Missoni‐Steinbacher  Florian Albrecht  Rob Lemmens  Stefan Lang  Jochen Albrecht  Martyna Stelmaszczuk‐Grska  Glenn Vancauwenberghe  Aida Monfort‐Muriach 《Transactions in GIS》2020,24(3):587-601

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Evidence for the occurrence of Vedde Ash in Sweden: radiocarbon and calendar age estimates     

Stefan Wastegrd  Svante Bjrck  Gran Possnert  Barbara Wohlfarth 《第四纪科学杂志》1998,13(3):271-274

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Book Review: Quartäre vegetationsgeschichte Europa - Methoden und Ergebnisse by Gerhard Lang. Gustav Fischer Verlag,Jena, Stuttgart,New York. 1994. 462 pp. DM 148. ISBN 3-334-60405-5 (hardcover)     

Barbara Wohlfarth 《第四纪科学杂志》1998,13(1):92-93

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使用地震波反映地球的内部结构     

刘春  张兆芳  李靖 《海洋地质前沿》2008,24(5):19-21

在地球内部产生的地震波提供了帮助我们更好地认识驱动板块运动的地幔对流方式的图案。海底扩张的发现和板块构造理论被接受以后的四十年,重要的盲点在于我们对驱动板块运动的地幔对流的方式以及导致地震、海啸和火山爆发等的原因知之甚少,目前仍然有许多激烈的争论。海洋岩石圈向下嵌入内陆板块,在板块汇聚边界处达到了地球的地幔底部了吗？细热的地幔柱上升通过板块中部“热点”火山下面的地幔了吗？  相似文献   

EAF implementation in Southern Africa: Lessons learnt     

Barbara Paterson  Samantha L. Petersen   《Marine Policy》2010,34(2):276-292

The practical implementation of an ecosystem approach to fisheries (EAF) management has proved difficult to achieve. Without simple and structured guidelines for implementing an EAF, managers are grappling with the complexity of implementation and the need to prioritise resources and management actions. Ecological risk assessment has been put forward as a structured procedure. There is a need to review regularly whether progress is being made in addressing the issues and priorities identified through ecological risk assessment. Such reviews require a framework providing clear objectives for the respective fishery and delineating the steps required towards their achievement. This paper proposes a generic framework for reviewing ecological risk assessments through stakeholder workshops. This framework is aided by a fuzzy logic tool to track EAF implementation and informs the development of proactive work plans which incorporate EAF objectives. The advantages and disadvantages of a generic and participatory approach are discussed and compared with other related methods for evaluating progress in implementing an EAF.  相似文献