Relations entre production organique et apports terrigènes dans les sédiments fluviatiles holocènes : observations et conclusions hétérodoxes     

Jean-Jacques Macaire  Christian Di-Giovanni  Florent Hinschberger 《Comptes Rendus Geoscience》2005,337(8):735-744

Accumulation of organic matter in fens of fluvial valleys is often related to a low terrigenous matter delivery and to palaeoenvironmental conditions inducing low mechanical erosion. These assumptions come from the interpretation of contents in organic (MO) and mineral (MM) matters in sediments, expressed in percents, and then exactly anticorrelated. Calculation of mass accumulation rates of MO $(T_{{\mathrm{a}}_{\mathrm{MO}}})$ and MM $(T_{{\mathrm{a}}_{\mathrm{MM}}})$, expressed in g?m^?2?yr^?1, shows that $T_{{\mathrm{a}}_{\mathrm{MO}}}$ and $T_{{\mathrm{a}}_{\mathrm{MM}}}$ generally are not anticorrelated and that high values of $T_{{\mathrm{a}}_{\mathrm{MO}}}$ and $T_{{\mathrm{a}}_{\mathrm{MM}}}$ could appear simultaneously. That expression of MO and MM accumulation makes it possible to precise the climatic and human impact on sedimentation. To cite this article: J.-J. Macaire et al., C. R. Geoscience 337 (2005).  相似文献   

Lichens as bioindicators in volcanic areas: Mt. Etna and Vulcano Island (Italy)     

M. F. Grasso  R. Clocchiatti  F. Carrot  C. Deschamps  F. Vurro 《Environmental Geology》1999,37(3):207-217

 The aim of this paper is to verify whether lichens have the capacity to accumulate atmospheric contaminators linked to volcanic activity. About 100 lichens were collected in 1994 and 1995 from two active volcanic areas in Italy: Mount Etna and Vulcano Island. Twenty-seven elements were analyzed for each individual lichen using Instrumental Neutronic Activation Analysis and Inductively Coupled Plasma-Mass Spectrometry. Lichen composition reflects the contribution of the volcanic particulate material, and the two areas investigated can be distinguished on the basis of the concentration of some lithophile elements. Moreover, the distribution in lichens of the elements (As, Sb, Br, Pb) – derived from gas emissions (plume, fumaroles) – also shows different geochemical trends on Mt. Etna and Vulcano. Received: 20 April 1998 · Accepted: 4 July 1998  相似文献   

Reservoir construction from the Newberry Volcano EGS Demonstration     

Trenton T Cladouhos  Susan Petty  Yini Nordin  Michael Moore  Kyla Grasso  Matt Uddenberg  Michael W Swyer 《地下水科学与工程》2014,2(3):1-7

The Newberry Volcano EGS Demonstration in central Oregon tests recent technological advances designed to reduce the cost of power generated by EGS in a hot, dry well (NWG 55-29) drilled in 2008. An EGS reservoir was created by injecting large volumes of cold water, causing existing fractures to slip in shear (known as hydroshearing) generating the seismic waves that can be used to map fracture location and size. At the Newberry Demonstration the final injectivity ranged between 1.4 and 1.7 L/s/MPa a ~6x improvement over the initial injectivity of the well. The injectivity improvement and seismic analysis indicate that previously impermeable fractures were enhanced during the NWG 55-29 stimulation.  相似文献   

Numerical modelling of mixed-sediment consolidation     

Florent Grasso  Pierre Le Hir  Philippe Bassoullet 《Ocean Dynamics》2015,65(4):607-616

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Sorption-desorption kinetics and toxic cell concentration in marine phytoplankton microalgae exposed to Linear Alkylbenzene Sulfonate     

Renaud F  Oberhänsli F  Teyssié JL  Miramand P  Temara A  Warnau M 《Marine pollution bulletin》2011,62(5):942-947

Linear Alkylbenzene Sulfonates (LAS) are ubiquitous surfactants. Traces can be found in coastal environments. Sorption and toxicity of C₁₂-LAS congeners were studied in controlled conditions (2-3500 μg C₁₂LAS/L) in five marine phytoplanktonic species, using standardized methods. IC₅₀ values ranged from 0.5 to 2 mg LAS/L. Sorption of ¹⁴C₁₂-6 LAS isomer was measured at environmentally relevant trace levels (4 μg/L) using liquid scintillation counting. Steady-state sorption on algae was reached within 5 h in the order dinoflagellate > diatoms > green algae. The sorption data, fitted a L-type Freundlich isotherm, indicating saturation. Desorption was rapid but a low LAS fraction was still sorbed after 24 h. Toxic cell concentration was 0.38 ± 0.09 mg/g for the studied species. LAS toxicity results from sorption on biological membranes leading to non-specific disturbance of algal growth. Results indicate that LAS concentrations in coastal environments do not represent a risk for these organisms.  相似文献   

A western boundary current east of New Caledonia: Observed characteristics     

Florent Gasparin  Alexandre Ganachaud  Christophe Maes 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(9):956-969

Waters from the South Equatorial Current (SEC), the northern branch of the South Pacific subtropical gyre, are a major supply of heat to the equatorial warm pool, and have an important contribution to climate variability and ENSO which motivated the Southwest Pacific Ocean and Climate Experiment (SPICE, CLIVAR/WCRP). Initially a broad westward current extending from the equator to 30°S, the SEC splits upon arriving at the major islands and archipelagoes of Fiji (18°S, 180°E), Vanuatu (16°S, 168°E), and New Caledonia (22°S, 165°E), resulting in a complex system of western boundary currents and zonal jets that feed the Coral and Solomon Seas. We focus here on the formation of one specific jet feeding the Coral Sea, the North Caledonian Jet (NCJ). Using a combination of recent oceanographic cruises, we describe the ocean circulation to the northeast of New Caledonia, where the SEC forms a western boundary current that ultimately becomes the NCJ. This current, which we document for the first time and propose to refer to as the East Caledonian Current (ECC), has its core located 10-100 km off the east coast of New Caledonia, and extends vertically to at least 1000 m depth. Water mass properties show continuous westward transports through the ECC, from the SEC to the NCJ in both the South Pacific Tropical Waters in the thermocline and Antarctic Intermediate Waters near 700 m depth. The ECC extends about 100 km horizontally; its average 0-1000 m transport was estimated at 14.5±3 Sv off the north tip of the New Caledonian reef, with a maximum of 20 Sv in May 2010. South of that the upstream branch of the ECC east of the Loyalty is close to 8 Sv suggesting an important additional contribution from central Pacific waters carried by the SEC at 16°S and diverted to our region through the western boundary current system east of Vanuatu.  相似文献   

A new insight into modelling the behaviour of unsaturated soils     

Wahib Arairo  Florent Prunier  Irini Djéran‐Maigre  Félix Darve 《国际地质力学数值与分析法杂志》2013,37(16):2629-2654

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Below-Ground Processes in Gap Models for Simulating Forest Response to Global Change   总被引：4，自引：0，他引：4  

Stan D. Wullschleger  Robert B. Jackson  William S. Currie  Andrew D. Friend  Yiqi Luo  Florent Mouillot  Yude Pan  Guofan Shao 《Climatic change》2001,51(3-4):449-473

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Mechanical behaviour of deep rock core samples from a seismically active gas field     

D. Fabre  J. -R. Grasso  Y. Orengo 《Pure and Applied Geophysics》1991,137(3):201-219

This study concerns the laboratory testing of core samples from massive sedimentary rocks from an oil and gas field. The depth of extraction of the samples analysed varies between 1000 and 5000 metres. In all, 65 tests were performed, most of which included systematic measurement of acoustic activity during loading. The aim of the testing was to determine which types of fracture could occur in the rock matrix under field-stress conditions by examining in particular the relationship between confining pressure and the transition from brittle to ductile behaviour. The results of the laboratory tests are used to predict the occurrence of seismic activity resulting from the depletion of the gas reservoir which has been monitored during the last twenty years.  相似文献   

Relation between seismic source parameters and mechanical properties of rocks: A case study     

Bruno Feignier  Jean-Robert Grasso 《Pure and Applied Geophysics》1991,137(3):175-199

This study attempts to determine the relation between source parameters and mechanical properties of the rock matrix in which the microseismic events occur. For this purpose, accurate geological, mechanical and seismological data were acquired on a gas field experiencing induced seismicity due to its reservoir pressure drop. More than 30 deep boreholes (depth greater than 4 km) are concentrated in a 10×10×5 km volume, providing core samples for both geological and mechanical assessment. In this study, we focus on induced seismic events recorded by the local seismic network, over a three-year-long period. Characteristics of the seismic sources were obtained using spectral analysis and a dynamic model of failure. Results point out correlation between physical parameters of the seismic sources and the geomechanical properties of the rocks involved. Maximal static stress drops are found to be associated with the mechanical strength of the geological strata where the rupture occurs. The fracture size, using a circular model of failure, is also found to be dependent on the geomechanical setting. It is found that the size of the seismic fractures is dependent on the layer thickness and the prefracturation of the medium, both factors influencing the extension of preexisting discontinuities. The parameters of the seismic sources also show important changes when the gas reservoir is reached. The reservoir unit experienced a 45 MPa pore fluid pressure drop over a period of 20 years.  相似文献