Book reviews     

Edith Brown Weiss  M. I. Budyko  Robert J. McAfee  Lester Machta 《Climatic change》1979,2(1):93-98

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Geostatistical Analysis of Inverse Problem Variables: Application to Seismic Tomography     

Juan L. Fernández Martínez  César O. Menéndez Pérez  Luis M. Pedruelo González  José P. Fernández Alvarez  Pablo Cienfuegos Suárez 《Mathematical Geology》2003,35(8):953-969

In this article we present a geostatistical approach to the transmission tomographic inverse problem, which is based on consideration of the inverse problem variables (velocity and traveltime errors) as regionalized variables (R.V.). Their structural analysis provides us with a new method to study the geophysical anisotropy of the rock, an important source of a priori information in order to design the anisotropic corrections. The underlying idea is that the geophysical structure can be deduced from the spatial structure of the regionalized variables which result from solving the tomographic problem with an isotropic algorithm. Also, the application of the structural analysis technique to the anisotropic corrected velocity field allows us to characterize the reliability of these corrections (model quality analysis). Geostatistical formalism also provides us with different techniques (parametric and non-parametric) to estimate and even simulate the velocity in the areas where this field has been considered anomalous based on field studies and on geophysical and statistical criteria. The kriging acts as a low-pass smoothing filter for the anomalous model parameters (velocities), but is not a substitute for an adequate filtering of the outliers before the inversion. This methodology opens the possibility of considering the inverse problem variables as stochastic processes, an important feature in cases where the tomogram is to be used as a tool of assessment to quantify the rock heterogeneities.  相似文献   

On asymmetries of solar spectral lines     

Claude Barambon  Edith A. Müller 《Solar physics》1979,64(2):201-212

The profiles of 43 lines have been observed at the centre and near the limb of the solar disk. Their asymmetry decreases towards the limb, and increases with the equivalent width and the mean heigth of line formation; no relation was found between the asymmetry and the line excitation potential, nor with the degree of ionization, nor with the usually adopted macroturbulent velocity. The asymmetry appears to be due to radial movements.  相似文献   

Uranium and Multi-element Release from Orthogneiss and Granite (Austria): Experimental Approach Versus Groundwater Composition     

Daniel Elster  Edith Haslinger  Martin Dietzel  Heinz Fröschl  Gerhard Schubert 《Aquatic Geochemistry》2018,24(4):279-306

In this study, the release of elements and in particular U from five Austrian orthogneiss and granite samples into a CO₂-bearing solution was investigated to describe the initial phase (24 h) of leaching focusing on the impact of ferrous (hydro)oxide formation. Experiments were conducted at ambient temperature by flushing CO₂:N₂ gas through the reactive solution (pH_initial?~?4.3) at a liquid:solid ratio of 10:1 with and without a reducing agent. The chemical evolution of the leaching solution was dominated by incongruent dissolution of silicates showing a parabolic kinetic behavior due to protective surface formation most likely caused by precipitation of amorphous Fe^III/Al hydroxides. However, the relative distribution of Ca, Mg and Sr in the leaching solution excellently traced the individual bulk rock composition. The mobilization of U was highly prevented under oxidizing conditions by sorption onto ferrous (hydro)oxides, which were precipitating through ongoing silicate leaching. Therefore, the leaching behavior of individual U-bearing minerals was less relevant for U release. At reducing conditions, the above elements were accumulated in the solution, although an oversaturation regarding U^IVO₂ was calculated. This indicates its inhibited formation within the experimental run time. The composition of experimental leaching solutions did not reflect analyzed groundwater compositions from investigated local rock-type aquifers indicating that reaction rate constants of siliceous rocks significantly differ between values found in nature and in the laboratory. Change in active mineral surface areas with ongoing weathering, accumulation of secondary precipitates, leached layer formation and given reaction time are key factors for distinct elemental release.  相似文献   

Ex post analysis of engineered tsunami mitigation measures in the town of Dichato,Chile     

Oportus  Maximiliano  Cienfuegos  Rodrigo  Urrutia  Alejandro  Aránguiz  Rafael  Catalán  Patricio A.  Hube  Matías A. 《Natural Hazards》2020,103(1):367-406

Natural Hazards - Due to Chile’s notorious and frequent seismic activity, earthquake- and tsunami-related studies have become a priority in the interest of developing effective...  相似文献   

Bridging a seasonal torrent: The Melfa river,southern Lazio,Italy     

I. Peter Martini  Edith M. Wightman  Pamela Hemphill 《Geoarchaeology》1987,2(2):149-159

The Melfa River is a torrent of the intramontane Lower Liri Valley, which has been a difficult barrier to cross since ancient times. It is dry and can be forded during the summer, but it experiences high floods during rainy reasons, with recurrent disruption of bridges. In Iron Age and early Roman times, fords and bridges were located near the confluence of the river with the valley plain, servicing the ancient Via Pedemontana. Later, faster routes with bridges were moved toward the flatter central area of the valley. There, Romans selected a crossing through wide braided reaches, taking advantage of fording, but consistently losing low lying, long bridges. Traces of one and possibly two such bridges remain along what was the Via Latina, from Fregellae to Aquino. For such bridges, the Romans used relatively strong piers, probably linked with readily detachable (by floods) and replaceable, wooden, flat roadways. The strategy of Medieval and Modern civilizations was instead to bridge the river in a more permanent way, with arches across the nearby deep gorges whose banks are composed of stable calcareous conglomerates and sandstones.  相似文献   

Characteristics of soil water movement in a grass slope in a karst peak‐cluster region,China          下载免费PDF全文

Wei Liu  Shijie Wang  Weijun Luo  Weiwei Dai  Edith Bai 《水文研究》2017,31(6):1331-1348

Soil water is very important in hilly areas with thin soil layers and deep groundwater tables, such as the karst peak‐cluster region of Southwest China. An investigation into soil water movement can provide insights into management of shallow water resources and soil nutrients, as well as prevention of groundwater pollution. In this study, ¹⁸O and ²H tracers were used to trace soil water movement in planar soil mass type microhabitats in the middle part of a steep hillslope covered by grasses in a karst peak‐cluster region of China. From May 2008 to July 2009, samples of precipitation and two types of soil water, which had different integrated degrees of mobility and were of different depth intervals or depths, were collected. The hydrogeochemical characteristics were compared between precipitation and soil water, and these data were applied in convolution‐based lumped parameter models. Our results indicated that vertical piston flow, rather than lateral flow along the soil–bedrock interface, played an important role in soil water percolation at least in the upper soil layer approximately 7 cm over the permeable bedrock. The mixing effect and preferential flow might also play a role in soil water percolation. In general, the evaporation effect on soil water was weak except for the uppermost 10 cm soil matrix water during winter. The lower limits of mean transit time of soil matrix flow passing through 5, 15, 25, 35, and 41.5 cm depths were 4.81, 7.70, 16.19, 21.85, and 27.44 days, respectively. Our study demonstrated the crucial functions of the soil reservoir in regulating the water cycle and could provide guidance on conservation of soil water and hydrological studies. The applied method was proved to be a suitable approach for investigating soil water movement on a monthly scale.  相似文献   

Natural and anthropogenic heavy metals in estuarine cohesive sediments: geochemistry and bioavailability     

Laura Edith Grecco  Eduardo Alberto G��mez  Sandra Elizabeth Bott��  ��ngel Omar Marcos  Jorge Eduardo Marcovecchio  Diana Graciela Cuadrado 《Ocean Dynamics》2011,61(2-3):285-293

The geochemistry, mineralogy, and grain size distribution of several estuarine cohesive sediment samples from potentially human-influenced areas without such an influence were analyzed to determine the natural heavy metal content and evaluate its impact on the Bahía Blanca estuarine environment. The data were compared with different ranges of concentrations for heavy metals in marine sediments established by the NOAA Screening Quick Reference Tables in which values range from background levels to those considered toxic to the marine environment. Our total heavy metal contents were below the established hazardous levels in all the analyzed samples, even though the potentially human-influenced areas (harbors, industry, urban spread) showed the highest total concentration values as well as greater percentages of bioavailable compounds. This would imply a low and not extensive anthropogenic input into the environment. The relatively high proportions in which Cd, Pb, and Cr appear as bioavailable compounds at some sites not influenced by human activity suggest the presence of a natural source for these elements. This could be attributed to the weathering of naturally occurring volcanic minerals, indicating that special care must be taken when monitoring of sediment for anthropogenic activity is carried out within this environment. According to the results obtained, and in order to minimize the environmental impact caused by periodic water injection dredging, relocation of sewage outfalls from vessel mooring areas into open waters is strongly recommended.  相似文献   

Apsidal rotation in the eclipsing binary AG Persei     

Edith J. Woodward  Robert H. Koch 《Astrophysics and Space Science》1987,129(1):187-193

New three-filter light curves of AG Per are given. These yield times of minimum light in accord with the known rate of apsidal rotation but do not improve that rate. These light curves and all other published historical ones have been treated with the code EBOP and are shown to give largely consistent geometric and photometric parameters no matter which orientation of the orbit is displayed to the observer.  相似文献   

Die Symposien der Internationalen Arbeitsgemeinschaft für Cyanophytenforschung (IAC)—ihre Entstehung und Bedeutung     

Dr. Edith Kann 《Aquatic Sciences - Research Across Boundaries》1977,39(2):152-166

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