Characterisation and multifaceted anisotropy assessment of Corvio sandstone for geological CO2 storage studies          下载免费PDF全文

Ismael Falcon‐Suarez  Jacobo Canal‐Vila  Jordi Delgado‐Martin  Laurence North  Angus Best 《Geophysical Prospecting》2017,65(5):1293-1311

We present a comprehensive characterisation of the physical, mineralogical, geomechanical, geophysical, and hydrodynamic properties of Corvio sandstone. This information, together with a detailed assessment of anisotropy, is needed to establish Corvio sandstone as a useful laboratory rock‐testing standard for well‐constrained studies of thermo–hydro–mechanical–chemical coupled phenomena associated with CO₂ storage practices and for geological reservoir studies in general. More than 200 core plugs of Corvio sandstone (38.1 and 50 mm diameters, 2:1 length‐to‐diameter ratio) were used in this characterisation study, with a rock porosity of 21.7 ± 1.2%, dry density 2036 ± 32 kg m^?3, and unconfined compressive and tensile strengths of 41 ± 3.28 and 2.3 ± 0.14 MPa, respectively. Geomechanical tests show that the rock behaves elastically between ～10 and ～18 MPa under unconfined conditions with associated Young's modulus and Poisson's ratio of 11.8 ± 2.8 GPa and 0.34 ± 0.01 GPa, respectively. Permeability abruptly decreases with confining pressure up to ～10 MPa and then stabilises at ～1 mD. Ultrasonic P‐ and S‐wave velocities vary from about 2.8–3.8 km s^?1 and 1.5–2.4 km s^?1, respectively, over confining and differential pressures between 0.1 and 35 MPa, allowing derivation of associated dynamic elastic moduli. Anisotropy was investigated using oriented core plugs for electrical resistivity, elastic wave velocity and attenuation, permeability, and tracer injection tests. Corvio sandstone shows weak transverse isotropy (symmetry axis normal to bedding) of <10% for velocity and <20% for attenuation.  相似文献   

Reproductive characteristics and steroid levels in the scleractinian coral Oculina patagonica inhabiting contaminated sites along the Israeli Mediterranean coast     

Armoza-Zvuloni R  Kramarsky-Winter E  Rosenfeld H  Shore LS  Segal R  Sharon D  Loya Y 《Marine pollution bulletin》2012,64(8):1556-1563

In this study we compared reproductive characteristics and steroid hormone levels in the non-indigenous scleractinian coral, Oculina patagonica, inhabiting contaminated vs. uncontaminated reference sites along the Israeli Mediterranean coast. Our results indicate significantly higher steroid levels in both seawater and coral tissue samples from contaminated sites as compared to reference sites, suggesting that corals tend to accumulate steroids from the surrounding waters. Despite their higher steroid levels, corals from the contaminated sites showed reproductive potential comparable to those of the reference sites. Interestingly, a clear distinction could be seen between corals exposed to pollution for long vs. short durations, with the latter showing a failure to complete gametogenesis. This suggests that reproduction in O. patagonica is susceptible to acute rather than chronic stress. The involvement of adjustment/adaptation processes may explain this species tolerance, and may reflect the ability of O. patagonica to successfully invade new areas in the Mediterranean Sea.  相似文献   

Review of self-potential methods in hydrogeophysics     

Laurence Jouniaux  Alexis Maineult  Véronique Naudet  Marc Pessel  Pascal Sailhac 《Comptes Rendus Geoscience》2009,341(10-11):928-936

The self-potential (SP) method is a passive geophysical method based on the natural occurrence of electrical fields on the Earth's surface. Combined with other geophysical methods, SP surveys are especially useful for localizing and quantifying groundwater flows and pollutant plume spreading, and estimating pertinent hydraulic properties of aquifers (water table, hydraulic conductivity). Laboratory experiments have shown that the involved coupling coefficients mainly depend on the fluid chemistry, conductivity and pH, and on the soil or rock properties. The interpretation of SP observations can be done qualitatively, for instance, by correlation of SP gradients with water fluxes (through electrokinetics) or salt fluxes (through electro-diffusion). In recent years, the interpretation has been improved with the help of modelling or/and inversion of the Poisson equation and endeavours to estimate hydraulic parameters by means of the intensity of electric current sources caused by underground flows.  相似文献   

Simulation of Soil Erosion and Sedimentation in Small River Basins     

Laurence A. Lewis 《自然地理学》2013,34(2):172-176

Potential erosion and sedimentation for three small stream basins near Dodoma, Tan-zania are simulated using SOILCART, a computer program recently developed to assist in the investi-gation of soil erosion problems. Using only widely available generalized data, the predicted values of soil erosion and sedimentation derived from SOILCART compare favorably to measured values which required a 2-year field investigation. Potential areas of high erosion are identified that could be amelio-rated with proper management. The potential use of SOILCART in preliminary evaluation of erosion and sedimentation problems promises useful results, especially in areas where small dams are proposed.  相似文献   

A numerical study on the role of wind forcing,bottom topography,and nonhydrostacy in coastal upwelling     

Lide Jiang  Xiao-Hai Yan  Yu-Heng Tseng  Laurence C. Breaker 《Estuarine, Coastal and Shelf Science》2011

The responses of coastal upwelling to different magnitudes of wind stress over a narrow and a wide shelf are studied using a 3-D primitive equation numerical model. The results show that the position of the upwelling front depends on both the strength and the duration of the wind forcing. The comparison between different shelf widths shows that wide shelf will limit the cold water intrusion, so that the corresponding decrease in sea surface temperature is less compared to narrow shelves. Besides, the difference between hydrostatic and nonhydrostatic model results shows that nonhydrostatic effects will enhance the growth of surface meandering, and can be more pronounced near steep fronts. Although difference does exist, our results show that the nonhydrostatic effects are very small at least in this idealized study case.  相似文献   

How good is good? Human values and Europe's proposed Marine Strategy Directive   总被引：2，自引：0，他引：2  

Mee LD  Jefferson RL  Laffoley Dd  Elliott M 《Marine pollution bulletin》2008,56(2):187-204

The adoption of the proposed European Marine Strategy Directive is an opportunity for a comprehensive policy for protecting, improving and sustainably using Europe's environmentally degraded seas. It calls for an ecosystem-based approach to management where humans are regarded as a key system component. Although the proposed wording has been the subject of fierce debate, the central policy goal remains achieving "Good Environmental Status". The interpretation of "good" is key to implementation and relates to human values and worldviews. We demonstrate how these vary widely across Europe. Solution of fundamental considerations such as the assignation of reference states, the balance between precautionary and evidence-based action, the degree of subsidiarity, and conservation strategies including marine protected areas, will ultimately depend upon public understanding, involvement in and support for the Directive. The social element, critical to effective adaptive management, requires greater attention within the context of a regional seas geographical framework.  相似文献   

Expression of the Early Toarcian negative carbon-isotope excursion in separated carbonate microfractions (Jurassic,Paris Basin)     

Michaël Hermoso  Laurence Le Callonnec  Fabrice Minoletti  Maurice Renard  Stephen P. Hesselbo 《Earth and Planetary Science Letters》2009,277(1-2):194-203

The causes of the pronounced negative excursion in carbon-isotope values that was recorded during the Early Toarcian Oceanic Anoxic Event (T-OAE) are still under debate, particularly with regard to the local versus global pattern of the excursion, and the extent to which recorded signals are under a diagenetic control. In this study we employ a novel microseparation technique in order to investigate the isotopic and mineralogical characteristics of different size fractions of the carbonate content from a Toarcian section recovered from the Sancerre–Couy borehole, southern Paris Basin. Beyond the recognition of a ? 6‰ δ¹³C excursion in the bulk carbonate content, our data also demonstrate that biogenic particles (such as coccoliths) and inorganic grains precipitated as early diagenetic phases (including dolomite) both record the excursion with the same magnitude. Although several black shales occur through the Paris Basin Toarcian section, it is only that associated with the onset of the OAE that coincides with a large negative carbon-isotope excursion. Taken together these observations indicate that during this event, the entire water column was characterized by homogeneous carbon-isotope values; such a pattern is incompatible with the idea that the negative excursion was generated simply through the upwelling of bottom waters enriched in re-mineralized organic carbon (cf. “the Küspert model”), since this would have required a strong vertical gradient in the water column. Additionally, the Paris Basin data show that the decrease in carbonate δ¹³C values during the OAE occurred in several discrete steps (each of some ? 2‰), as has previously been found for organic carbon substrates in other European sections. The stepped nature of the isotopic profile, which is part of a stratigraphic signature previously ascribed to Milankovitch forcing, is compatible with regular pulsed input of light carbon into the whole atmosphere–ocean system from a climatically sensitive source such as gas hydrate, or from thermal methanogenesis of organic-rich sediments in the Karoo–Ferrar large igneous province. Contrasts in the amplitude of the negative carbon-isotope excursion on a regional scale remain an important unexplained aspect of the Toarcian record.  相似文献   

An ultrasoft X-ray source (RX 215319−1514) and discovery of a narrow‐line Seyfert 1 galaxy     

Kulinder Pal Singh  Laurence R. Jones 《Monthly notices of the Royal Astronomical Society》2000,312(2):380-386

We present results on the identification of the optical counterpart of an ultrasoft X-ray source discovered with ROSAT . Two optical candidates – a galaxy and a star – are found within the error circle of the X-ray source position. Optical spectroscopy of the two candidates reveals that (a) the galaxy is a narrow-line Seyfert type 1 galaxy, and (b) the star is a late A-type or an early F-type. The F _x F _v ratio is too high for the star to be the counterpart of the X-ray source, but consistent with that for an active galaxy. Although higher-resolution X-ray imaging of the region is needed to definitely settle the question of the counterpart of the X-ray source, the narrow-line Seyfert 1 galaxy is the best candidate. The spectral properties of the newly discovered narrow-line Seyfert 1 galaxy are also presented, including its extreme X-ray power-law spectral index of Γ≥4.  相似文献   

Best practices for the use of meteorite names in publications     

Philipp R. Heck  Christopher Herd  Jeffrey N. Grossman  Dmitry Badjukov  Audrey Bouvier  Emma Bullock  Hasnaa Chennaoui‐Aoudjehane  Vinciane Debaille  Tasha L. Dunn  Denton S. Ebel  Ludovic Ferrire  Laurence Garvie  Jrme Gattacceca  Matthieu Gounelle  Richard Herd  Trevor Ireland  Emmanuel Jacquet  Robert J. Macke  Tim McCoy  Francis M. McCubbin  Takashi Mikouchi  Knut Metzler  Mathieu Roskosz  Caroline Smith  Meenakshi Wadhwa  Linda Welzenbach‐Fries  Toru Yada  Akira Yamaguchi  Ryan A. Zeigler  Michael Zolensky 《Meteoritics & planetary science》2019,54(7):1397-1400

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Nonlinear influences on ocean waves observed by X-band radar     

Li-Chung Wu  Dong-Jiing Doong  Beng-Chun Lee  Laurence Zsu-Hsin Chuang  Chia Chuen Kao 《Marine Geophysical Researches》2008,29(1):43-50

The purpose of this study is to discuss the influence of signal nonlinearity upon X-band radar observations. A method for estimating the degree of nonlinearity by bispectral analysis was applied and discussed. We found that bispectral analyses from spatial radar backscatter series are similar to results obtained from water level time series. In addition, the average nonlinear degree from radar backscatter is related to wind speed. The accuracy of wave observations derived by consideration of the nonlinear effect from radar backscatter was also investigated. The estimated error in wave height from the radar data is also related to the degree of nonlinearity. In order to improve accuracy, the modulation transfer function method was applied in order to eliminate the influence of nonlinearity.  相似文献