Dynamics of a wave-dominated tidal inlet and influence on adjacent beaches,Currumbin Creek,Gold Coast,Australia     

Bruno Castelle  Julien Bourget  Nathalie Molnar  Darrell Strauss  Sophie Deschamps  Rodger Tomlinson 《Coastal Engineering》2007

Currumbin Creek on the Australian Gold Coast is a wave-dominated tidal inlet which exhibits a particularly active morphology. The recent history of Currumbin Creek entrance has seen rapid growth of the entrance for access to the ocean by fishermen, as a world class surfing site, and as a recreational area. Before the construction of two groynes in the 70's, Currumbin Creek entrance was highly variable in terms of inlet location and sand bar characteristics due to a cyclical behaviour of spit migration. Nowadays, the entrance is stabilised. However, natural processes continue with the entrance infilling causing flood and navigation issues, resulting in a regular dredging program to maintain an open entrance and for regular beach nourishment plans.  相似文献   

Comparative study of radiation-induced damage in magnesium aluminate spinel by means of IL,CL and RBS/C techniques     

Iwona Jozwik  Jacek Jagielski  Grzegorz Gawlik  Przemyslaw Jozwik  Renata Ratajczak  Gerard Panczer  Nathalie Moncoffre  Anna Wajler  Agata Sidorowicz  Lionel Thomé 《Physics and Chemistry of Minerals》2016,43(6):439-445

A comparative study of damage accumulation in magnesium aluminate spinel (MgAl₂O₄) has been conducted using ionoluminescence (IL), cathodoluminescence (CL) and Rutherford Backscattering Spectrometry/channeling (RBS/C) techniques. MgAl₂O₄ single crystal and polycrystalline samples were irradiated with 320 keV Ar⁺ ions at fluencies ranging from 1 × 10¹² to 2 × 10¹⁶ cm^?2 in order to create various levels of radiation damage. RBS/C measurements provided quantitative data about damage concentration in the samples. These values were then compared to the luminescence measurements. The results obtained by IL and RBS/C methods demonstrate a two-step character of damage buildup process. The CL data analysis points to the three-step damage accumulation mechanism involving the first defect transformation at fluencies of about 10¹³ cm^?2 and second at about 10¹⁵ cm^?2. The rate of changes resulting from the formation of nonluminescent recombination centers is clearly nonlinear and cannot be described in terms of continuous accumulation of point defects. Both, IL and CL techniques, appear as new, complementary tools bringing new possibilities in the damage accumulation studies in single- and polycrystalline materials.  相似文献   

Roman road pollution assessed by elemental and lead isotope geochemistry in East Belgium     

Virginie Renson  Nathalie Fagel  Nadine Mattielli  Serge Nekrassoff  Maurice Streel  Franois De Vleeschouwer 《Applied Geochemistry》2008,23(12):3253-3266

The ability of inorganic geochemistry to record environmental change and especially human impact has been evidenced by several studies across Europe, especially in peat, where it is possible to record the impact of agriculture, mining and other industries. However, despite the numerous investigations on the impact of ancient human activities such as ore mining and smelting, little attention has been paid to geochemistry as a tool to solve problems of palaeopollution in the surroundings of archaeological sites. This paper presents geochemical evidence of the impact of a possible early Roman road built in SE Belgian peatland. Increased Zn and Pb concentrations suggest that Pb–Zn ores were transported on the road. Lead isotope analyses suggest that these ores are locally derived, being compatible with those found in the nearby Pb–Zn ore deposits from East Belgium. Present results provide direct evidence that East Belgian Pb–Zn ores were already being mined during Roman times, i.e. earlier than previously suspected (i.e. 14th century) and that Zn appears to be relatively immobile here. On a broader scale, it also demonstrates that such an early road already had an impact on the environment in terms of metal pollution. This paper enlarges on the range of possibilities offered by geochemistry in the field of geoarchaeology.  相似文献   

P-T-t modelling, fluid circulation, and 39Ar-40Ar and Rb-Sr mica ages in the Aar Massif shear zones (Swiss Alps)     

Nathalie Challandes  Didier Marquer  Igor M. Villa 《Swiss Journal of Geoscience》2008,101(2):269-288

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Non-stationary emission of the blazar S4 0954+658 over a wide range of wavelength     

A. E. Volvach  V. S. Bychkova  M. G. Larionov  N. S. Kardashev  L. N. Volvach  V. V. Vlasyuk  O. I. Spiridonova  A. Lähteenmäki  M. Tornikoski  M. F. Aller  H. D. Aller  G. Pooley  L. Carrasco  A. Porras  E. Recillas 《Astronomy Reports》2016,60(12):1035-1045

Data from long-term multi-frequency monitoring are used to analyze variations in the flux density of the active galactic nucleus S4 0954+658. These data were obtained at the CrimeanAstrophysical Observatory, the Metsähovi Radio Observatory of Aalto University, the University of Michigan Radio Astronomy Observatory, the Cavendish Laboratory of Cambridge University, the Special Astrophysical Observatory, and the National Institute of Astrophysics, Optics, and Electronics; 0.1–300-GeV data from the Fermi space gamma-ray observatory were also used. Radio data at 4.8, 8, 14.5, 15, 22.2, and 36.8 GHz are considered together with optical and near-infrared data in the R, J, H, and K filters.  相似文献   

Effects of mid‐twenty‐first century climate and land cover change on the hydrology of the Puget Sound basin,Washington     

Lan Cuo  Tazebe K. Beyene  Nathalie Voisin  Fengge Su  Dennis P. Lettenmaier  Marina Alberti  Jeffrey E. Richey 《水文研究》2011,25(11):1729-1753

The distributed hydrology–soil–vegetation model (DHSVM) was used to study the potential impacts of projected future land cover and climate change on the hydrology of the Puget Sound basin, Washington, in the mid‐twenty‐first century. A 60‐year climate model output, archived for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), was statistically downscaled and used as input to DHSVM. From the DHSVM output, we extracted multi‐decadal averages of seasonal streamflow, annual maximum flow, snow water equivalent (SWE), and evapotranspiration centred around 2030 and 2050. Future land cover was represented by a 2027 projection, which was extended to 2050, and DHSVM was run (with current climate) for these future land cover projections. In general, the climate change signal alone on sub‐basin streamflow was evidenced primarily through changes in the timing of winter and spring runoff, and slight increases in the annual runoff. Runoff changes in the uplands were attributable both to climate (increased winter precipitation, less snow) and land cover change (mostly reduced vegetation maturity). The most climatically sensitive parts of the uplands were in areas where the current winter precipitation is in the rain–snow transition zone. Changes in land cover were generally more important than climate change in the lowlands, where a substantial change to more urbanized land use and increased runoff was predicted. Both the annual total and seasonal distribution of freshwater flux to Puget Sound are more sensitive to climate change impacts than to land cover change, primarily because most of the runoff originates in the uplands. Both climate and land cover change slightly increase the annual freshwater flux to Puget Sound. Changes in the seasonal distribution of freshwater flux are mostly related to climate change, and consist of double‐digit increases in winter flows and decreases in summer and fall flows. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Use of major and selected trace elements to describe mixing processes in a water reservoir   总被引：1，自引：0，他引：1  

Nathalie Gassama  Constantin Cocirta  Haino Uwe Kasper 《Comptes Rendus Geoscience》2012,344(1):25-32

Data on temperature, major constituents and some trace elements, measured in the dissolved and particulate phases, were used to identify the hydrodynamics of a reservoir (the Bicaz reservoir, Romania). Results revealed that the reservoir experiences two thermal stratifications per year (summer and winter). However, the summer stratification is delayed by the high river inflow of June–July. Two layers were identified, a surface and a deep layer, whose location and impact vary with time. The surface layer originates from the river inflow (intrusion layer) and the deep current is produced by the outflow (velocity current). According to season, the river inflow either supplies the deep current or remains recordable up to the dam. Consequently, the structure of the water column, and thus the biogeochemical processes within it, are governed both by thermal stratification and by these layers.  相似文献   

Mars mantle convection: Influence of phase transitions with core cooling     

Nathalie Michel  Olivier Forni 《Planetary and Space Science》2011,59(8):741-748

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Nitrile gas chemistry in Titan’s atmosphere     

Thomas Gautier  Nathalie Carrasco  Cyril Szopa  Guy Cernogora 《Icarus》2011,213(2):625-635

This work presents the first study of the gaseous products resulting from the partial dissociation of methane and nitrogen in the PAMPRE experimental setup simulating Titan’s atmospheric chemistry.Using cryogenic trapping, the gaseous products generated from the chemical reactions occurring in the reactor have been trapped. Analyses of these products by gas chromatography coupled to mass spectrometry have allowed the detection and identification of more than 30 reaction products. Most of them are identified as nitrile species, accompanied by aliphatic hydrocarbons and a few aromatics compounds. The observed species are in agreement with the data from the recent Cassini-Huygens mission as well as from other laboratory setups capable of dissociating nitrogen and methane. This work emphasizes the probable importance of nitrogen-bearing compounds in the chemistry taking place in Titan’s atmosphere.Furthermore, a quantification of mono-nitriles with saturated alkyl chains has been performed relatively to hydrogen cyanide and shows a power law dependence in their concentration. This dependence is consistent with the Cassini-INMS data and Titan’s photochemical models.An empirical relationship has been extracted from our experimental data: [C_xH_2x−1N] = 100x⁻⁵, where x is the number of carbon atoms in the nitrile molecule. This relationship can be directly used in order to foretell the concentration of heavier nitriles induced by chemistry in Titan’s atmosphere.  相似文献   

Hydrological role of karst in the Chalk aquifer of Upper Normandy,France     

Sanae El Janyani  Jean-Paul Dupont  Nicolas Massei  Smail Slimani  Nathalie Dörfliger 《Hydrogeology Journal》2014,22(3):663-677

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