Zur Sedimentologie eines arktischen Deltas (Colville Delta,Nordalaska)     

Dr. Werner Fürbringer 《International Journal of Earth Sciences》1977,66(1):577-614

Zusammenfassung Im August 1971 wurden vom Verfasser Feldarbeiten zur Sedimentologie des Colville Deltas, Alaska, durchgeführt. Aus subaquatischen Typlokalitäten wurden Probenkerne gezogen und auf Strukturen, Korngrößen und Mineralogie hin untersucht. Neben konventionellen Labormethoden kamen moderne elektronische Verfahren zum Einsatz (Röntgenradiographie, Röntgendiffraktometrie, Elektronenmikroskopie). Die Arbeiten sind Teil eines Programmes, dessen Gesamtleitung Prof. Dr. H. J. Walker, Baton Rouge, USA, hatte und das unterstützt wurde von: Arctic Program and Geography Programs, Office of Naval Research.

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In August 1971, sedimentological field work was carried out by the author in the Colville River delta, Alaska. Short cores were taken from several deltaic environments and analyzed for structure and composition. Laboratory analysis included both conventional laboratory methods and modern electronic techniques (radiography, X-ray diffractometry, electron microscopy). The research reported is part of a program headed by Prof. Dr. H. J. Walker, Baton Rouge, USA, and was supported by the Arctic Program and Geography Programs, Office of Naval Research.

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Résumé En auguste 1971 l'auteur a étudié sur le terrain la sédimentologie du delta de Colville (Alaska). On a prélevé des échantillons dans des profiles de divers environnements typiques; on en a examiné les structures et la composition par les méthodes traditionelles et électroniques (rayons X, radiographie et diffractométrie, microscope électronique). Ces investigations font partie d'un programme sous la direction du Prof. Dr. H. J. Walker, Baton Rouge, USA, subventionné par »Arctic Program and Geography Programs, Office of Naval Research«.

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1971 . , . , . , - , . , . . H. J. Walker, Baton Rouge, USA Arctic Program, and Geography Programs, Office of Naval Research.

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On model integration in operational flood forecasting     

Micha Werner  Doug Whitfield 《水文研究》2007,21(11):1519-1521

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Salinograph trends as indicators of the recession characteristics of stream components     

A. D. Werner  M. Wood  C. T. Simmons  D. A. Lockington 《水文研究》2008,22(16):3020-3028

Compared to hydrograph recession analysis, which is widely applied in engineering hydrology, the quantitative assessment of stream salinity with time (i.e. the salinograph) has received significantly less attention. In particular, while in many previous hydrological studies an inverse relationship between hydrograph and salinograph responses is apparent, the concept of salinity accession (the inversely related salinity counterpart to hydrograph recession) has not been introduced nor quantitatively evaluated in previous literature. In this study, we conduct a mathematical analysis of salinograph accession, and determine new quantitative relationships between salinity accession and hydrograph recession parameters. An equation is formulated that reproduces the general trend in salinity accession. A salinity accession parameter k_c is then introduced and is shown to be the ratio of direct runoff to total stream flow recession parameters: k_r/k. The groundwater recession parameter k_g was estimated using a simple and rapid method that uses both salinograph and hydrograph data. Salinity accession type‐curves illustrate that under certain conditions, the relative steepness of individual salinographs is dependent upon the ratio of groundwater salinity to direct runoff salinity: C_g/C_r. The salinity accession algorithms are applied to two contrasting field settings: Scott Creek, South Australia and Sandy Creek, northern Queensland, Australia. It was found that k_g > k during periods of obvious stream flow recession, for the events analysed. Salinograph accession behaviour was fairly similar for both sites, despite contrasting environments. Using assumed end‐member salinities for groundwater and direct runoff based upon field observations, the behaviour of k_c from the Scott Creek site was approximately reproduced by varying the initial groundwater to runoff flow ratio: Q_g0/Q_r0, within reasonable parameter ranges. The use of salinograph information when used in addition to standard hydrograph analyses provided useful information on recession characteristics of stream components. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Lithospheric extension and the opening of the Red Sea: sediment-basalt relationships in Yemen*     

Martin Menzies  Dan Bosence  Hamed A. El-Nakha  Salah Al-Khirbash  Mohamed A. Al-Kadasi  Abdulkarim Al Subbary 《地学学报》1990,2(4):340-350

This paper analyses new field and radiometric age data on the timing of extension, sedimentation and magmatism related to the opening of the Red Sea. The first evidence of widespread extension is found in synsedimentary fissures in the fluviatile to shallow marine Tawilah Formation of Cretaceous to early Tertiary age. The first indication of magmatism is the eruption of alkaline basalts (43.5–21.2 Ma) on to marine and non-marine sandstones of lower to middle Tertiary age. The lack of an angular unconformity at the sediment-basalt contact, over a period of 25 Myr, corroborates a diachronous relationship between the Tawilah sandstones and the Yemen Volcanics. These data also indicate that the onset of volcanism in Yemen was in the Eocene, as is the case in Ethiopia and Saudi Arabia. A passive rifting model is supported by early extension and sedimentation followed by syn- and post-tectonic magmatism.  相似文献   

Shark interactions in pelagic longline fisheries   总被引：1，自引：0，他引：1  

Eric Gilman  Shelley Clarke  Nigel Brothers  Joanna Alfaro-Shigueto  John Mandelman  Jeff Mangel  Samantha Petersen  Susanna Piovano  Nicola Thomson  Paul Dalzell  Miguel Donoso  Meidad Goren  Tim Werner 《Marine Policy》2008

Substantial ecological, economic and social problems result from shark interactions in pelagic longline fisheries. Improved understanding of industry attitudes and practices towards shark interactions assists with managing these problems. Information on fisher knowledge and new strategies for shark avoidance may benefit sharks and fishers. A study of 12 pelagic longline fisheries from eight countries shows that incentives to avoid sharks vary along a continuum, based on whether sharks represent an economic disadvantage or advantage. Shark avoidance practices are limited, including avoiding certain areas, moving when shark interaction rates are high, using fish instead of squid for bait and deeper setting. Some conventionally employed fishing gear and methods used to target non-shark species contribute to shark avoidance. Shark repellents hold promise; more research and development is needed. Development of specifically designed equipment to discard sharks could improve shark post release survival prospects, reduce gear loss and improve crew safety. With expanding exploitation of sharks for fins and meat, improved data collection, monitoring and precautionary shark management measures are needed to ensure that shark fishing mortality levels are sustainable.  相似文献   

Charcoal and fossil wood from palaeosols,sediments and artificial structures indicating Late Holocene woodland decline in southern Tibet (China)     

Knut Kaiser  Lars Opgenoorth  Werner H. Schoch  Georg Miehe 《Quaternary Science Reviews》2009,28(15-16):1539-1554

Charcoal and fossil wood taken from palaeosols, sediments and artificial structures were analysed in order to evaluate the regional pedoanthracological potential and to obtain information on Holocene environmental changes, particularly on possible past tree occurrences in southern Tibet. This research was initiated by the question to what extent this area is influenced by past human impact. Even recent evaluations have perceived the present treeless desertic environment of southern Tibet as natural, and the previous Holocene palaeoenvironmental changes detected were predominantly interpreted to be climate-determined. The material analysed – comprising a total of 53 botanical spectra and 55 radiocarbon datings from 46 sampling sites (c. 3500–4700 m a.s.l.) – represents the largest systematically obtained data set of charcoal available from Tibet so far. 27 taxa were determined comprising trees, (dwarf-) shrubs and herbs as well as grasses. The predominant tree taxa were Juniperus, Hippophae, Salix and Betula. According to their present-day occurrence in the region, the genera Juniperus and Hippophae can be explicitly attributed to tree species. Further, less frequently detected tree taxa were Populus, Pinus, Quercus, Taxus and Pseudotsuga. Charcoal of Juniperus mainly occurred on southern exposures, whereas Betula was associated with northern exposures. In contrast, the (partly) phreatophytic taxa Hippophae and Salix showed no prevalent orientation. The distribution of radiocarbon ages on charcoal revealed a discontinuous record of burning events cumulating in the Late Holocene (c. 5700–0 cal BP). For southern Tibet, these results indicated a Late Holocene vegetation change from woodlands to the present desertic pastures. As agrarian economies in southern and south-eastern Tibet date back to c. 3700 and 5700 cal BP, respectively, and the present-day climate is suitable for tree growth up to c. 4600 m a.s.l., we concluded that the Late Holocene loss or thinning out of woodlands had been primarily caused by humans.  相似文献   

Organized bacterial assemblies in manganese nodules: evidence for a role of S-layers in metal deposition   总被引：1，自引：0，他引：1  

Xiaohong Wang  Heinz C. Schröder  Ute Schloßmacher  Werner E. G. Müller 《Geo-Marine Letters》2009,29(2):85-91

Polymetallic/ferro-manganese nodules (Mn-nodules) reach sizes of up to 10 cm in diameter and are abundantly found on the seabed. To date, the origin of Mn-nodules remains unclear, and both abiogenic and biogenic origins have been proposed. In search of evidence for a contribution of microbial processes to the formation of Mn-nodules, we analyzed those spherical nodules which contain a concentrically banded texture in their interior. The Mn-nodules were collected at a depth of 5,152 m from the Clarion-Clipperton Zone. Our high-resolution scanning electron microscopy analyses reveal first published evidence that endolithic microorganisms exist and are arranged in a highly organized manner on plane mineral surfaces within the nodules. These microorganisms are adorned on their surfaces with S-layers, which are indicative for bacteria. Moreover, the data suggest that these S-layers are the crystallization seeds for the mineralization process. We conclude that the mineral material of the Mn-nodule has a biogenic origin, and hope that these data will contribute to the development of biotechnological approaches to concentrate metals from seawater using bacteria in bioreactors.  相似文献   

Microbial photosynthesis in coral reef sediments (Heron Reef, Australia)     

Ursula Werner  Anna Blazejak  Paul Bird  Gabriele Eickert  Raphaela Schoon  Raeid M.M. Abed  Andrew Bissett  Dirk de Beer   《Estuarine, Coastal and Shelf Science》2008,76(4):876-888

We investigated microphytobenthic photosynthesis at four stations in the coral reef sediments at Heron Reef, Australia. The microphytobenthos was dominated by diatoms, dinoflagellates and cyanobacteria, as indicated by biomarker pigment analysis. Conspicuous algae firmly attached to the sand grains (ca. 100 μm in diameter, surrounded by a hard transparent wall) were rich in peridinin, a marker pigment for dinoflagellates, but also showed a high diversity based on cyanobacterial 16S rDNA gene sequence analysis. Specimens of these algae that were buried below the photic zone exhibited an unexpected stimulation of respiration by light, resulting in an increase of local oxygen concentrations upon darkening. Net photosynthesis of the sediments varied between 1.9 and 8.5 mmol O₂ m⁻² h⁻¹ and was strongly correlated with Chl a content, which lay between 31 and 84 mg m⁻². An estimate based on our spatially limited dataset indicates that the microphytobenthic production for the entire reef is in the order of magnitude of the production estimated for corals. Photosynthesis stimulated calcification at all investigated sites (0.2–1.0 mmol Ca²⁺ m⁻² h⁻¹). The sediments of at least three stations were net calcifying. Sedimentary N₂-fixation rates (measured by acetylene reduction assays at two sites) ranged between 0.9 to 3.9 mmol N₂ m⁻² h⁻¹ and were highest in the light, indicating the importance of heterocystous cyanobacteria. In coral fingers no N₂-fixation was measurable, which stresses the importance of the sediment compartment for reef nitrogen cycling.  相似文献   

INTEGRAL/XMM views on the MeV source GRO J1411-64     

Diego F. Torres  Shu Zhang  Olaf Reimer  Xavier Barcons  Amalia Corral  Valentí Bosch-Ramon  Josep M. Paredes  Gustavo E. Romero  Jin Qu  Werner Collmar  Volker Schönfelder  Yousaf Butt 《Astrophysics and Space Science》2007,309(1-4):17-21

The COMPTEL unidentified source GRO J 1411-64 was observed by INTEGRAL and XMM-Newton in 2005. The Circinus Galaxy is the only source detected within the 4σ location error of GRO J1411-64, but in here excluded as the possible counterpart. At soft X-rays, 22 reliable and statistically significant sources (likelihood >10) were extracted and analyzed from XMM-Newton data. Only one of these sources, XMMU J141255.6-635932, is spectrally compatible with GRO J1411-64 although the fact the soft X-ray observations do not cover the full extent of the COMPTEL source position uncertainty make an association hard to quantify and thus risky. At the best location of the source, detections at hard X-rays show only upper limits, which, together with MeV results obtained by COMPTEL suggest the existence of a peak in power output located somewhere between 300–700 keV for the so-called low state. Such a spectrum resembles those in blazars or microquasars, and might suggest at work by the models accordingly. However, an analysis using a microquasar model consisting on a magnetized conical jet filled with relativistic electrons, shows that it is hard to comply with all observational constrains. This fact and the non-detection at hard X-rays introduce an a-posteriori question mark upon the physical reality of this source, what is discussed here.  相似文献   

Geomagnetic secular variations 0-2700 yr BP recorded by lake sediments from Waginger See (southeastern Bavaria)     

J. Werner  G. Michler  A. Schult 《Geophysical Journal International》1990,101(2):479-485

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