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981.
Anne Battani Thomas Smith Jean Charles Robinet Bernard Lavielle 《Geochimica et cosmochimica acta》2011,75(23):7566-7584
Helium concentration measurements made on water and rock samples collected at various depths along a 2000 m depth borehole drilled in the eastern part of the Paris basin and reaching the Triassic conglomerates were used to establish a vertical profile of dissolved helium concentration throughout the entire Mesozoic sedimentary pile. Wireline logging tools were used to measure rock density, porosity and U and Th contents every 15 cm in the various formations. Samples from the deepest Muschelkalk and Buntsandstein show a very good agreement between measured and calculated 4He porewater contents. Shallower levels show lower and lower 4He concentrations compared to calculated values when going upwards. The data set obtained by wireline logging measurements was used as inputs for numerical simulations of 1D He production/diffusion throughout the 2000 m profile. Several assumptions regarding the transport properties in the various sedimentary layers were tested and all were found to yield fairly good agreement between modeled and measured He concentrations. There is no need to invoke either a transient regime or a deep crustal He flux in this “quiet” (seismically inactive) part of the Paris basin. Moreover, the modeling results suggest that the Keuper massive halite level associated with the upper Muschelkalk pre-evaporitic series efficiently isolates the overlying layers from any input from deeper formations in the Meuse/Haute Marne area. 相似文献
982.
Influence of high-resolution wind forcing on hydrodynamic modeling of the Gulf of Lions 总被引:2,自引:2,他引:0
Amandine Schaeffer Pierre Garreau Anne Molcard Philippe Fraunié Yann Seity 《Ocean Dynamics》2011,61(11):1823-1844
The impact of the choice of high-resolution atmospheric forcing on ocean summertime circulation in the Gulf of Lions (GoL;
Mediterranean Sea) is evaluated using three different datasets: AROME (2.5 km, 1 h), ALADIN (9.5 km, 3 h), and MM5 (9 km,
3 h). A short-term ocean simulation covering a 3-month summer period was performed on a 400-m configuration of the GoL. The
main regional features of both wind and oceanic dynamics were well-reproduced by all three atmospheric models. Yet, at smaller
scales and for specific hydrodynamic processes, some differences became apparent. Inertial oscillations and mesoscale variability
were accentuated when high-resolution forcing was used. Sensitivity tests suggest a predominant role for spatial rather than
temporal resolution of wind. The determinant influence of wind stress curl was evidenced, both in the representation of a
mesoscale eddy structure and in the generation of a specific upwelling cell in the north-western part of the gulf. 相似文献
983.
Cross polarization (CP) magic angle spinning (MAS) 13C NMR spectroscopy is a solid state NMR technique widely applied to study the chemical composition of natural organic matter. In high magnetic fields (>7 T), fast sample spinning is required in order to reduce the influence of spinning sidebands underlying other chemical shift regions. As the spinning speed increases, the Hartmann-Hahn matching profiles break down into a series of narrow matching bands. In order to account for this instability variable amplitude cross polarization techniques (e.g. VACP, ramp-CP) have been developed. In the present study, we experimentally verified the stability of the Hartmann-Hahn condition under two MAS speeds for different samples with known structure and two different humic acids. For a complete restoration of flat matching profiles, large ramp sizes were needed. The matching profiles of the humic acids showed that both samples needed different ramp sizes to restore flat profiles. A set up based on the matching profiles of the commonly used glycine would have led to an insufficient ramp size for one of the humic acids. For the characterization of natural organic matter, we hence recommend to roughly set the matching conditions with a standard and subsequently optimize the matching conditions on a more complex, preferably representative, sample such as a humic acid. We would suggest to either run an array of different ramp sizes until maximum signal intensity is reached for all chemical shift regions or, in the case of unavailable measurement time, to use a ramp size twice the spinning speed. 相似文献
984.
Anne Mehlin Sørensen Finn Surlyk 《Cretaceous Research》2011,32(4):472-479
A gastropod fauna comprising 17 species, each represented by a limited number of specimens, is described from a Late Cretaceous, late early Campanian rocky shore at Ivö Klack, southern Sweden. The gastropod fauna is associated with the most diverse ancient rocky shore fauna ever found. However, the low gastropod species diversity compared to the faunas of modern rocky shores is ascribed to taphonomic factors, notably dissolution of the aragonitic shells, but the predominance of epifaunal herbivores is indicative of a guild structure similar to that found on modern rocky shores. The presence of drill holes assigned to the ichnospecies Oichnus simplex suggests the former presence of muricid gastropods which have not been found as body fossils. A single drill hole is referred to Oichnus paraboloides and was probably made by a naticid gastropod. The infaunal mode of life of naticids makes preservation of such drill holes difficult, since the majority of infaunal prey such as burrowing bivalves has aragonitic shells which are not preserved. The relatively high number of species in comparison to many other Late Cretaceous rocky shore faunas, offers an opportunity to compare gastropod guild structure at Ivö Klack with modern counterparts, even though taphonomic processes such as mechanical destruction and aragonite dissolution have played an important role in the fossil gastropod assemblage. 相似文献
985.
Proteomics is a new and promising approach to evaluate potential effects of pollution. In order to investigate if there is a direct link between the protein expression profiles obtained by the SELDI-TOF MS technology and effects observed at the organism level in fish, plasma samples from unexposed and 20 ppb alkylphenol exposed female Atlantic cod (Gadus morhua) with high phenotypic variation in gonadosomatic index (GSI) were analyzed by SELDI-TOF MS. Principle component analysis (PCA) showed that the major proteomic variation present in the dataset (i.e. 23.6%) could be significantly correlated to the individual variation in GSI, which indicates that SELDI-TOF MS data can reflect effects observed at higher levels of organization in fish. Further exploration of the other principal components revealed an additional proteomic pattern specific for the alkylphenol exposed females. Hence, this study supports the usefulness of SELDI-TOF MS as a proteomic tool in ecotoxicological research. 相似文献
986.
Binyam L. Alemu Per Aagaard Ingrid Anne Munz Elin Skurtveit 《Applied Geochemistry》2011,26(12):1975-1989
Crushed rock from two caprock samples, a carbonate-rich shale and a clay-rich shale, were reacted with a mixture of brine and supercritical CO2 (CO2–brine) in a laboratory batch reactor, at different temperature and pressure conditions. The samples were cored from a proposed underground CO2 storage site near the town of Longyearbyen in Svalbard. The reacting fluid was a mixture of 1 M NaCl solution and CO2 (110 bar) and the water/rock ratio was 20:1. Carbon dioxide was injected into the reactors after the solution had been bubbled with N2, in order to mimic O2-depleted natural storage conditions. A control reaction was also run on the clay-rich shale sample, where the crushed rock was reacted with brine (CO2-free brine) at the same experimental conditions. A total of 8 batch reaction experiments were run at temperatures ranging from 80 to 250 °C and total pressures of 110 bar (∼40 bar for the control experiment). The experiments lasted 1–5 weeks.Fluid analysis showed that the aqueous concentration of major elements (i.e. Ca, Mg, Fe, K, Al) and SiO2 increased in all experiments. Release rates of Fe and SiO2 were more pronounced in solutions reacted with CO2–brine as compared to those reacted with CO2-free brine. For samples reacted with the CO2–brine, lower temperature reactions (80 °C) released much more Fe and SiO2 than higher temperature reactions (150–250 °C). Analysis by SEM and XRD of reacted solids also revealed changes in mineralogical compositions. The carbonate-rich shale was more reactive at 250 °C, as revealed by the dissolution of plagioclase and clay minerals (illite and chlorite), dissolution and re-precipitation of carbonates, and the formation of smectite. Carbon dioxide was also permanently sequestered as calcite in the same sample. The clay-rich shale reacted with CO2–brine did not show major mineralogical alteration. However, a significant amount of analcime was formed in the clay-rich shale reacted with CO2-free brine; while no trace of analcime was observed in either of the samples reacted with CO2–brine. 相似文献
987.
On 16 October 1979, a tsunami of a local origin hits the French Riviera around Nice, France, killing 8 people and generating
important economic losses. Its impact was felt from Hyères to Menton, France. The main effect of this tsunami was flooding
in the neighborhoods of La Salis and La Garoupe, Antibes, France. A synthesis of unpublished reports written in the context
of an administrative investigation was conducted. Various archives were also consulted (newspapers, fire and rescue unit reports,
insurance reports, etc.), and a field survey was organized in 2009 to record testimonies from the inhabitants who witnessed
the flood in La Salis, Antibes, the area where the effects of the tsunami were the greatest. A geo-database of the neighborhood
of La Salis was built using available aerial imagery, land cover data and digital terrain models, to reconstruct the surface
of the flooded area as it was in 1979 and as it is now. Comparing precise testimonies and the 1979 topographic information
available allowed the authors to precisely map the flood and to deduce the runup values which reached 3.5 m locally, with
a maximal distance of flooding of 150 m inland. This paper provides modelers with precious information about the extent of
flooding and the time sequence in order to reconstitute the propagation and flooding of the 16 October 1979 tsunami. This
information highlights the fact that the French Riviera is a low hazard, but high vulnerability area. 相似文献
988.
Michael Ballón Arnaud Bertrand Anne Lebourges-Dhaussy Mariano Gutiérrez Patricia Ayón Daniel Grados François Gerlotto 《Progress in Oceanography》2011,91(4):360-381
The Northern Humboldt Current system (NHCS) produces more fish per unit area than any other region in the world. Although the system produces enough macrozooplankton to sustain its high production of forage fish, the paucity of information on macrozooplankton hampers research into the system. In this study, we estimated the biomass of the epipelagic crustacean macrozooplankton from the NHCS during both austral summer and spring 2005. To do this, we developed a bi-frequency acoustic method and extracted high-resolution information on the biomass and the patterns of distribution of crustacean macrozooplankton, fish and other marine compartments. We found that, although macrozooplankton comprises a number of distinct organisms, the euphausiids were the zooplankton group that better fitted the patterns from independent net sampling zooplankton data. Also, the similarities between the nocturnal patterns of size and biomass macrozooplankton distribution from this study and the known patterns of euphausiids, in particular Euphausia mucronata, suggest that euphausiids were the main constituent of the estimated nocturnal acoustic macrozooplankton biomass even if other organisms such as large copepods may have contributed considerably to the macrozooplankton biomass. The total macrozooplankton biomass was estimated to about 105 g m−2, i.e., two to five times more than previous estimates. This direct biomass estimation of macrozooplankton is in agreement with the new findings in trophic ecology indicating that forage fish consume mainly macrozooplankton. This high biomass also supports the current hypotheses explaining the NHCS high fish production. Using the method, we are able to revisit present-day and historical acoustic databases and extract high-resolution data on macrozooplankton, a key ecological compartment of the ecosystem. Since zooplankton is the link between the physically driven primary producers and the biologically driven tertiary consumers, this information is essential to achieve a mechanistic understanding of the system, from physics to top predators. 相似文献
989.
The objective of this study was to determine if exploitative competition between between juvenile Chinook salmon (Oncorhynchus tshawytscha) and threespine stickleback (Gasterosteus aculeatus) reduces the foraging opportunity of juvenile Chinook salmon in tidal channels of the Columbia River estuary. We sampled
Chinook salmon and stickleback diets monthly and over a diel cycle in spatially distinct emergent marshes of the Columbia
River estuary. Diets of the two fish species did not differ among marsh systems, but both fish species exhibited diel and
seasonal differences in diet composition. Diet overlap between the two fish species was greatest in March and June. Exploitative
competition was unlikely based on a comparison between consumption rates and estimated invertebrate production. 相似文献
990.
Peng Lu Qi Fu William E. SeyfriedJr Anne Hereford Chen Zhu 《Environmental Earth Sciences》2011,62(1):101-118
The injection of CO2 into deep saline aquifers is being considered as an option for greenhouse gas mitigation. However, the response of an aquifer
to the injected CO2 is largely unknown. Experiments involving the reaction of Navajo Sandstone with acidic brine were conducted at 200°C and
25 or 30 MPa to evaluate the extent of fluid–rock interactions. The first experiment examined sandstone interaction with CO2-impregnated brine; the second experiment examined sandstone dissolution in CO2-free acidic brine; the third one is carried out in a mixed-flow reactor and designed to measure sandstone dissolution rates
based on time-series Si concentrations. The solution chemistry data indicate that the SiO2(aq) increases gradually and pH increases slowly with reaction progress. Silicate minerals in the sandstone display textures
(dissolution features, secondary mineralization), indicating that these phases are reacting strongly with the fluid. Dissolution
of feldspars and conversion of smectite to illite are likely to be the two reactions that contribute to the release of SiO2(aq). The product minerals present at the end of the experiments are illite, illite/smectite, allophane, and carbonate minerals
(for the CO2-charged system). Dissolved CO2 is likely to acidify the brine and to provide a source of carbon for the precipitation of carbonate minerals. Mineral trapping
through the precipitation of carbonate minerals is favored thermodynamically and was observed in the experiments. The chemical
reactions likely increase the bulk porosity of the sandstone due to dissolution of silicate minerals. However, allophane and
illite/smectite fill voids in sandstone grains. There is no evidence for the removal of clay coatings due to chemical reactions.
It is uncertain whether the mechanical forces near an injection well would mobilize the smectite and allophane and clog pore
throats. Trace amounts of metals, including Cu, Zn, and Ba, were mobilized. 相似文献