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571.
Pollution source characterization by the Partitioning Interwell Tracer Test method requires the assessment of the partitioning coefficient of the tracers with the pollutant. Experiments conducted on batch tests (static) and laboratory columns (dynamic) indicated a partitioning kinetics between the reactive tracer (4-methyl 2-pentanol) and the organic phase (trichlorethene); the partitioning coefficient decreases when the flow velocity through the porous medium increases. This partitioning kinetics has been confirmed by the interpretation of the tracer breakthrough curves with a first-order kinetic transfer model. To cite this article: M. Bohy et al., C. R. Geoscience 336 (2004). 相似文献
572.
Olivier Maurel Jean-Patrick Respaut Patrick Monié Nicolas Arnaud Maurice Brunel 《Comptes Rendus Geoscience》2004,336(12):1091-1098
Zircon UPb dating by SIMS of the Mont-Louis granite yields an age of 305±5 Ma, intrepreted to reflect the igneous emplacement age of the massif. It is in agreement with the Hercynian syntectonic character of Pyrenees granite. 40Ar/39Ar on hornblende, biotite and K-feldspar permit, to estimate the massif cooling. A rapid temperature decrease (≈30 °C/Ma) is revealed from Westphalian to Late Stephanian, coeval with the emplacement of a laccolithe in the upper crust. Then, the cooling rate decreases to ≈1 °C/Ma. This would be consistent with a long time residence for the pluton from the Late Palaeozoic to the Early Cainozoic at 6–8 km depth. To cite this article: O. Maurel et al., C. R. Geoscience 336 (2004). 相似文献
573.
Natural speciation of Zn at the micrometer scale in a clayey soil using X-ray fluorescence, absorption, and diffraction 总被引:1,自引:0,他引:1
Alain Manceau Matthew A. Marcus Olivier Proux Nicolas Geoffroy 《Geochimica et cosmochimica acta》2004,68(11):2467-2483
Combined use of synchrotron-based X-ray fluorescence (SXRF), diffraction (XRD), and absorption (EXAFS) with an X-ray spot size as small as five micrometers allows us to examine noninvasively heterogeneous soils and sediments. Specifically, the speciation of trace metals at low bulk concentrations and the nature of host minerals can be probed with a level of detail unattainable by other techniques. The potential of this novel analytical approach is demonstrated by determining the Zn species in the solid phases of a pristine horizon of a clayey acidic soil (pH 4.5-5.0) having a Zn concentration of 128 mg/kg. The sample presents a differentiated fabric under the optical microscope with traces of localized manganiferous, ferriferous and argillaceous accumulations. The high chemical and textural heterogeneity of this soil offers an opportunity to identify new Zn species and to confirm the existence of others proposed from published least-squares fits of bulk averaged EXAFS spectra. As many as five to six Zn species were observed: sphalerite (ZnS), zincochromite (ZnCr2O4), Zn-containing phyllosilicate and lithiophorite, and Zn-sorbed ferrihydrite or Zn-phosphate, the results being less definitive for these two last species. Bulk EXAFS spectroscopy applied to the powdered soil indicated that Zn is predominantly associated with phyllosilicates, all other species amounting to < ∼10 to 20% of total zinc. The role of lithiophorite in the sequestration of zinc in soils had been inferred previously, but the firm identification of lithiophorite in this study serves as an excellent demonstration of the capabilities of combined micro-SXRF/XRD/EXAFS measurements. The micro-EXAFS spectrum collected in an area containing only phyllosilicates could not be simulated assuming a single Zn structural environment. Two distinct octahedrally-coordinated crystallographic sites (i.e., two EXAFS components) were considered: one site located within the phyllosilicate structure (isomorphic cationic substitution in the octahedral sheet) and another in the interlayer region in the form of a Zn-sorbed hydroxy-Al interlayered species. This second subspecies is less certain and further investigation of the individual EXAFS spectrum of this component is needed to precise its exact nature and the uptake mechanism of zinc in it. 相似文献
574.
Thomas Franck Rizza Magali Bellier Olivier Billant Jérémy Dussouillez Philippe Fleury Jules Delanghe Doriane Ollivier Vincent Godard Vincent Talon Brigitte 《Natural Hazards》2021,105(2):1453-1490
Natural Hazards - The Provence region, located in the south-east of France, has experienced a few destructive earthquakes during the last centuries, such as the 1909 Lambesc earthquake or the 1509... 相似文献
575.
Olivier Petit Marcel Kuper Elena López-Gunn Jean-Daniel Rinaudo Ali Daoudi Caroline Lejars 《Hydrogeology Journal》2017,25(6):1549-1564
The aim of this paper is to investigate the notion of collapse of agricultural groundwater economies using the adaptive-cycle analytical framework. This framework was applied to four case studies in southern Europe and North Africa to question and discuss the dynamics of agricultural groundwater economies. In two case studies (Saiss in Morocco and Clain basin in France), the imminent physical or socio-economic collapse was a major concern for stakeholders and the early signs of collapse led to re-organization of the groundwater economy. In the other two cases (Biskra in Algeria and Almeria in Spain), collapse was either not yet a concern or had been temporarily resolved through increased efficiency and access to additional water resources. This comparative analysis shows the importance of taking the early signs of collapse into account. These signs can be either related to resource depletion or to environmental and socio-economic impacts. Beyond these four case studies, the large number of groundwater economies under threat in (semi-)arid areas should present a warning regarding their possible collapse. Collapse can have severe and irreversible consequences in some cases, but it can also mean new opportunities and changes. 相似文献
576.
Laurent Oscar Couzinié Simon Zeh Armin Vanderhaeghe Olivier Moyen Jean-François Villaros Arnaud Gardien Véronique Chelle-Michou Cyril 《International Journal of Earth Sciences》2017,106(2):421-451
International Journal of Earth Sciences - The late stages of the Variscan orogeny are characterized by middle to lower crustal melting and intrusion of voluminous granitoids throughout the belt,... 相似文献
577.
Olivier S. Barnouin Maria T. Zuber David E. Smith Gregory A. Neumann Robert R. Herrick John E. Chappelow Scott L. Murchie Louise M. Prockter 《Icarus》2012,219(1):414-427
Topographic data measured from the Mercury Laser Altimeter (MLA) and the Mercury Dual Imaging System (MDIS) aboard the MESSENGER spacecraft were used for investigations of the relationship between depth and diameter for impact craters on Mercury. Results using data from the MESSENGER flybys of the innermost planet indicate that most of the craters measured with MLA are shallower than those previously measured by using Mariner 10 images. MDIS images of these same MLA-measured craters show that they have been modified. The use of shadow measurement techniques, which were found to be accurate relative to the MLA results, indicate that both small bowl-shaped and large complex craters that are fresh possess depth-to-diameter ratios that are in good agreement with those measured from Mariner 10 images. The preliminary data also show that the depths of modified craters are shallower relative to fresh ones, and might provide quantitative estimates of crater in-filling by subsequent volcanic or impact processes. The diameter that defines the transition from simple to complex craters on Mercury based on MESSENGER data is consistent with that reported from Mariner 10 data. 相似文献
578.
Sébastien Loock Hervé Diot Benjamin Van Wyk de Vries Patrick Launeau Olivier Merle Fabienne Vadeboin Michael S. Petronis 《Journal of Volcanology and Geothermal Research》2008
Anisotropy of magnetic susceptibility (AMS) data analysis is a convenient method used to investigate strain and flow during lava flow emplacement. In order to make a sound interpretation, the origin of the AMS signal must be verified. Two questions must be answered: 1) what phase, or phases carry the AMS signal and 2) when was the AMS fabric acquired? The verification steps themselves can provide extra data for interpreting lava flow conditions. Here, we present a methodology to answer the two questions in a 6 km-long Chaîne des Puys trachybasaltic lava flow that descended into the future site of Clermont Ferrand (France) 45,000 years ago. Knowledge of lava flow emplacement will be useful specifically to this site, if a reactivation of the volcanic chain occurs. The results are also of more general interest to understand lava flow emplacement dynamics. 相似文献
579.
Perturbation of fluvial sediment fluxes following the 2008 Wenchuan earthquake 总被引:1,自引:0,他引:1
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Wei Wang Vincent Godard Jing Liu‐Zeng Dirk Scherler Chong Xu Jinyu Zhang Kejia Xie Olivier Bellier Claire Ansberque Julia de Sigoyer ASTER Team 《地球表面变化过程与地形》2017,42(15):2611-2622
Quantifying the removal of co‐seismic landslide material after a large‐magnitude earthquake is central to our understanding of geomorphic recovery from seismic events and the topographic evolution of tectonically active mountain ranges. In order to gain more insight into the fluvial erosion response to co‐seismic landslides, we focus on the sediment fluxes of rivers flowing through the rupture zone of the 2008 Mw 7.9 Wenchuan earthquake in the Longmen Shan of the eastern Tibetan Plateau. Over the post‐seismic period of 2008–2013, we annually collected river sediment samples (0.25–1 mm) at 19 locations and measured the concentration of cosmogenic 10Be in quartz. When compared with published pre‐earthquake data, the 10Be concentrations declined dramatically after the earthquake at all sampling sites, but with significant spatial differences in the amplitude of this decrease, and were starting to increase toward pre‐earthquake level in several basins over the 5‐year survey. Our analysis shows that the amplitude of 10Be decrease is controlled by the amount of landslides directly connected to the river network. Calculations based on 10Be mixing budgets indicate that the sediment flux of the 0.25–1 mm size fraction increased up to sixfold following the Wenchuan earthquake. Our results also suggest that fluvial erosion became supply limited shortly after the earthquake, and predict that it could take a few years to several decades for fluvial sediment fluxes to go back to pre‐earthquake characteristics, depending on catchment properties. We also estimate that it will take at least decades and possibly up to thousands of years to remove the co‐seismic landslide materials from the catchments in the Longmen Shan. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
580.
Sand spits with distal hooks have been well documented from coasts with low to moderate tidal ranges, unlike high tidal-range environments. Datasets from 15 LiDAR and 3 UAV surveys between 2009 and 2019 on the Agon spit in Normandy (France), a setting with one of the largest tidal ranges in the world (mean spring tidal range: 11 m), combined with in-situ hydrodynamic records between 2013 and 2017, highlight a three-stage pattern of spit hook evolution. Stage 1 (2009–2013) commenced with the onshore migration and attachment of a swash bar, followed by persistent spit accretion updrift of the bar and erosion downdrift because of the slow speed of bar migration in this large tidal-range environment. In stage 2 (2013–2016), three overwash events and a 220 m-wide breach culminating in the total destruction of the spit during winter 2015–2016 involved the landward mobilization of thousands of cubic metres of sand. These events occurred during short durations (a few hours) when spring high tides coincided with relatively energetic waves, underscoring the importance of storms in rapid spit morphological change. Strong spring tidal currents maintained the breach. Stage 3 (2016–2019) has involved new hook construction through welding of a swash bar and spit longshore extension, highlighting the resilience of the spit over the 10-year period, and involving a positive sediment balance of 244 000 m3. The three stages bring out, by virtue of the temporal density of LiDAR and UAV data used, a high detail of spit evolution relative to earlier studies in this macrotidal setting. The large tidal range strongly modulates the role of waves and wave-generated longshore currents, the main process drivers of spit evolution, by favouring long periods of inertia in the course of the spring–neap tidal cycle, but also brief episodes of significant morphological change when storm waves coincide with spring high tides. © 2020 John Wiley & Sons, Ltd. 相似文献