Feeding of Plaice (Pleuronectes Platessa L.) and COD (Gadus Morhua L.) Larvae     

Nordeng  Hans; Bratland  Per 《ICES Journal of Marine Science》1971,34(1):51-57

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Extreme wave forces on submerged wave energy devices     

Per Brevig  Martin Greenhow  Tor Vinje 《Applied Ocean Research》1982,4(4):219-225

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Prototype LAAS Architecture Design Considerations     

Boris S. Pervan  Samuel P. Pullen  David G. Lawrence  Konstantin Gromov  Jock Christie  Guttorm Opshaug  Vicky Lu  Ping-Ya Ko  Per Enge  Bradford W. Parkinson 《GPS Solutions》1998,2(1):49-61

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Recurring Jökulhlaups in Sälka, Northern Sweden     

Per Klingbjer 《Geografiska Annaler: Series A, Physical Geography》2004,86(2):169-179

An ice‐dammed lake at the margin of the glacier Sälkaglaciären, in the Kebnekaise Mountains in northern Sweden, drained suddenly in July 2003 producing a flood with a measured peak discharge of 9.5±0.25 m³s^‐1. The total lake volume of 4.55×10⁵ million³ drained within two days. The hydrograph of this event is characteristic of a jökulhlaup controlled by a single basal ice tunnel that enlarges due to melting. The jökulhlaup had an exponential rise to a peak discharge, and following the peak, a very steep fall in discharge as the water supply to the drainage system ceased. A similar jökulhlaup was observed in August 1990 with an estimated release of 8.05×10⁵ m³ water. Jökulhlaups at Sälkaglaciären are recurring events and have been indirectly observed since the 1950s.  相似文献   

Sorption and anaerobic biodegradation of soluble aromatic compounds during groundwater transport. 1. Laboratory column experiments     

Zuoping Zheng  Per Aagaard  Gijs D. Breedveld 《Environmental Geology》2002,41(8):922-932

. This paper deals with sorption and anaerobic biodegradation of the soluble aromatic fraction of jet fuel and how it is influenced by pore-water velocity during transport in a groundwater aquifer. The study was carried out as controlled laboratory column experiments. A binary mixture of toluene and 1,2,4-trimethylbenzene with a concentration ratio of 2:1 was used through the entire investigations. The column experiments were conducted with contaminated sediments and groundwater, taken from wells at a field research site. The columns were operated anaerobically under continuous-flow conditions at 10 °C in a temperature-controlled refrigerator. Two percent sodium azide was added to the injection solution of two of the columns to prevent biodegradation of the studied organic mixture. Chloride was used as a conservative tracer to characterize the hydrodynamic parameters such as dispersivity and porosity of the columns. The results showed that both compounds in the mixture were attenuated because of sorption and biodegradation processes in the columns. 1,2,4-trimethylbenzene was attenuated more significantly than toluene. Biodegradation of toluene was coupled mainly with the microbial reduction of ferric iron, whereas 1,2,4-trimethylbenzene, in contrast, was mostly sorbed. Their sorption and biodegradation were studied with different pore-water velocities, and a mass balance approach was applied to calculate biodegradation rates. The biodegradation rates of toluene were –0.16, –0.21, and –0.26 (unit: mM day^–1) for pore-water velocities of 96, 82.4, and 54.9 (unit: cm day^–1), respectively. This indicates that a decrease in the pore-water velocity significantly enhanced the biodegradation of toluene, consistent with other reports in the literature. For 1,2,4-trimethylbenzene the biodegradation rates were –0.05, –0.13 (unit: mM day^–1) for pore-water velocities of 96 and 82.4 (unit: cm day^–1), respectively. The biodegradation rate of 1,2,4-trimethylbenzene did not increase at the lowest pore water velocity as expected. This might be a result of substrate competition.  相似文献   

Radio observations of polar regions     

Preben Gudmandsen  John Apel  William Campbell  Per Gloersen  Ulf Karstrom  Richard Moore  Robert Suchman  Dennis Trizna 《Boundary-Layer Meteorology》1978,13(1-4):413-416

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Kimberlitic zircons — A possible aid in prospecting for kimberlites     

P. Kresten  P. Fels  G. Berggren 《Mineralium Deposita》1975,10(1):47-56

Kimberlitic zircons from 16 intrusions in Lesotho, the Republic of South Africa, and Tanzania have been investigated. The following characteristics distinguish the kimberlitic zircons from the zircons derived from most other sources: 1. Rounded to subrounded grains predominate; euhedral zircons are very rare. 2. Perfect parting in several directions, mainly (100) and (111). 3. Lattice distortions occur (decreasing molar volume). 4. High abundancy of fluid inclusions, occupying healed fractures. 5. Uranium contents less than 30 ppm U. Low contents of Th, Y, P, REE. 6. Whitish alteration rims composed of monoclinic and tetragonal zirconia in varying proportions are common. — The use of zircons in order to identify and trace kimberlite intrusives is discussed, as there may be a possible connection between some properties of the kimberlitic zircons and the diamond grade of their host rocks.  相似文献   

Towards a quaternary time scale     

W. A. Berggren  L. H. Burckle  M. B. Cita  H. B. S. Cooke  B. M. Funnell  S. Gartner  J. D. Hays  J. P. Kennett  N. D. Opdyke  L. Pastouret  N. J. Shackleton  Y. Takayanagi 《Quaternary Research》1980,13(3):277-302

Nine first-appearance datums (FADs), twenty-three last-appearance datums (LADs), and three other micropaleontological datums are related to the magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction time scales to provide a preliminary basis for subdivision of the Quaternary in deep-sea sediments. The magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction scales have been correlated by determination on the same core materials, and absolute dates applied by ⁴⁰K/⁴⁰Ar or ¹⁴C dating of materials in known positions on one or another of these scales. FADS and LADs have been determined in cores for which either a magnetic-reversal, oxygen-isotope, or calcite-dissolution/coarse-fraction scale has also been available. Altogether 3 FADs and 5 LADs based on diatoms, 4 FADs and 5 LADs based on calcareous nannoplankton, 1 FAD and 8 LADs based on radiolarians, 1 FAD and 5 LADs based on planktonic foraminifers, 2 acme datums, and 1 ratio reversal datum have been determined, and absolute dates inferred by interpolation from known dates on the reference time scales. Some of the FADs and LADs apply or are synchronous only over limited areas of the oceans; others appear to be synchronous throughout the oceans. The base of the Quaternary is set at the top of the Olduvai event at 1.7 my. Four FADs, twelve LADs, two acme datums, and one ratio reversal datum occur above the base of the Quaternary at an average rate of about 1 per 100,000 yr. Five FADs and twelve LADs are recognized in the 0.8-my interval between the top of the Olduvai event and the Gauss/Matuyama Boundary at 2.5 my at an average incidence of about 1 per 50,000 yr.  相似文献   

Supradetachment to rift basin transition recorded in continental to marine deposition; Paleogene Bandar Jissah Basin,NE Oman     

Christopher Sb Serck  Alvar Braathen  Snorre Olaussen  Per Terje Osmundsen  Ivar Midtkandal  Anna Elisabeth van Yperen  Kjetil Indrevr 《Basin Research》2021,33(1):544-569

A transition from supradetachment to rift basin signature is recorded in the ~1,500 m thick succession of continental to shallow marine conglomerates, mixed carbonate‐siliciclastic shallow marine sediments and carbonate ramp deposits preserved in the Bandar Jissah Basin, located southeast of Muscat in the Sultanate of Oman. During deposition, isostatically‐driven uplift rotated the underlying Banurama Detachment and basin fill ~45° before both were cut by the steep Wadi Kabir Fault as the basin progressed to a rift‐style bathymetry that controlled sedimentary facies belts and growth packages. The upper Paleocene to lower Eocene Jafnayn Formation was deposited in a supradetachment basin controlled by the Banurama Detachment. Alluvial fan conglomerates sourced from the Semail Ophiolite and the Saih Hatat window overlie the ophiolitic substrate and display sedimentary transport directions parallel to tectonic transport in the Banurama Detachment. The continental strata grade into braidplain, mouth bar, shoreface and carbonate ramp deposits. Subsequent detachment‐related folding of the basin during deposition of the Eocene Rusayl and lower Seeb formations marks the early transition towards a rift‐style basin setting. The folding, which caused drainage diversion and is affiliated with sedimentary growth packages, coincided with uplift‐isostasy as the Banurama Detachment was abandoned and the steeper Marina, Yiti Beach and Wadi Kabir faults were activated. The upper Seeb Formation records the late transition to rift‐style basin phase, with fault‐controlled sedimentary growth packages and facies distributions. A predominance of carbonates over siliciclastic sediments resulted from increasing near‐fault accommodation, complemented by reduced sedimentary input from upland catchments. Hence, facies distributions in the Bandar Jissah Basin reflect the progression from detachment to rift‐style tectonics, adding to the understanding of post‐orogenic extensional basin systems.  相似文献   

Coastal profile response to sea level rise: a process‐based approach     

Troels Aagaard  Per Sørensen 《地球表面变化过程与地形》2012,37(3):354-362

Prevailing ideas and calculations of coastal response to sea level rise (SLR) are often based on the Bruun model (Bruun P., Sea‐level rise as a cause of shore erosion, Journal Waterways Harbors Division, ASCE 88 : 117–130, 1962) that predicts upward and landward transfer of an equilibrium profile during SLR through offshore sediment transport on the shoreface. The model is based on a number of assumptions of questionable validity as well as outdated concepts on how sediment is transported across the shoreface. This contribution takes a numerical modelling approach that is based on first‐order processes contributing to the movement of sediment across the shoreface. Using a wave transformation model that predicts hydrodynamic processes driving cross‐shore sediment transport and an energetics‐based model for the coupling between hydrodynamics and sediment transport, we show that cross‐shore sediment transport is mainly onshore directed at the boundary between the lower and the upper shoreface, in agreement with the model proposed by Davidson‐Arnott (Conceptual model of the effects of sea level rise on sandy coasts, Journal of Coastal Research 21 : 1166–1172, 2005). The transition from onshore to offshore directed transport is located well within the surf zone and with a rising sea level this transition point becomes displaced landward and upward. Tests also show that substrate slope is of fundamental importance to the manner in which beaches react to rising sea level. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献