横穿贝加尔湖山脉北部寒区的线性工程     

I.Y. Malchikova 《冰川冻土》2004,26(Z1):206-209

The development of North Transbaikalye mineral resources (e. g. the Chiney deposit of iron titanium-vanadium-magnetite ores and Udokan copper deposits) is impossible without the establishment of industrial and transport infrastructure, one component of which are linear engineering constructions (drive railways, by-line auto roads, platform passages, protecting constructions, and others). However,on condition of spreading permafrost rocks this is conjugated with certain ecological risk just as from the transport network objects so for the objects themselves. A special attention is paid in the paper to considering of problems of projecting and constructing railways on the Udokan ridge.  相似文献   

探测冰盖和多年冻土层的融冰探头研发     

Norbert I. K 《冰川冻土》2004,26(Z1):310-318

The exploration of ice sheets by melting vertical holes into the ground has some tradition in terrestrial glaciology. Such probes have been used since the 1960's to investigate the vertical structure of the ice in Greenland and Antarctica and in alpine glaciers. In this paper we look into the possibility to develop similar devices for use on extraterrestrial icy bodies, like e.g. the polar areas on Mars or the icy satellites of the outer solar system. We report on some basic experiments performed in the cryo-vacuum laboratory of the Space Research Institute of the Austrian Academy of Sciences, Graz. In these experiments the penetration of a simple melting probe into compact and porous water ice (with a snow-like texture) was monitored, both under vacuum conditions and under air pressure. The observed penetration speeds for a given power supply are compared with a simple mathematical model. We conclude that a miniature melting probe with small overall dimensions and a reasonable power demand could well be part of the payload of a future planetary mission, for example to the poles of Mars. Such missions are currently under discussion in several space agencies. Moreover such probes could also e? ectively be used in terrestrial environments. A possible design is presented at the end of the paper.  相似文献   

A Least-squares Approach to Depth Determination from Numerical Horizontal Self-potential Gradients     

E. M. Abdelrahman  H. S. Saber  K. S. Essa  M. A. Fouda 《Pure and Applied Geophysics》2004,161(2):399-411

We have developed a least-squares minimization approach to depth determination of a buried ore deposit from numerical horizontal gradients obtained from self-potential (SP) data using filters of successive window lengths (graticule spacings). The problem of depth determination from SP gradients has been transformed into the problem of finding a solution to a nonlinear equation of the form f(z)=0. Formulas have been derived for vertical and horizontal cylinders and spheres. Procedures are also formulated to estimate the electrical dipole moment and the polarization angle. The method is applied to synthetic data with and without random noise. Finally, the validity of the method is tested on two field examples. In both cases, the depth obtained is found to be in a very good agreement with that obtained from drilling information.  相似文献   

Space-time mapping of soil salinity using probabilistic bayesian maximum entropy     

A. Douaik  M. van Meirvenne  T. Tóth  M. Serre 《Stochastic Environmental Research and Risk Assessment (SERRA)》2004,18(4):219-227

The mapping of saline soils is the first task before any reclamation effort. Reclamation is based on the knowledge of soil salinity in space and how it evolves with time. Soil salinity is traditionally determined by soil sampling and laboratory analysis. Recently, it became possible to complement these hard data with soft secondary data made available using field sensors like electrode probes. In this study, we had two data sets. The first includes measurements of field salinity (EC_a) at 413 locations and 19 time instants. The second, which is a subset of the first (13 to 20 locations), contains, in addition to EC_a, salinity determined in the laboratory (EC_2.5). Based on a procedure of cross-validation, we compared the prediction performance in the space-time domain of 3 methods: kriging using either only hard data (HK) or hard and mid interval soft data (HMIK), and Bayesian maximum entropy (BME) using probabilistic soft data. We found that BME was less biased, more accurate and giving estimates, which were better correlated with the observed values than the two kriging techniques. In addition, BME allowed one to delineate with better detail saline from non-saline areas.  相似文献   

Microseismicity and active deformation of Messinia,SW Greece     

J. Papoulia  J. Makris 《Journal of Seismology》2004,8(4):439-451

By deploying a 30 3-component digital seismic array in the Messiniakos gulf and the surrounding region, we recorded for a period of 45 days the microseismic activity. With a minimum of six records per event, we located 1121 earthquakes corresponding to an average of 20 events per day. For the hypocenter location we used a local velocity model adopted to two controlled source seismic experiments. Within the array, traveltime residuals were within ± 0.2 s and the epicentral accuracy in the order of ± 2 km, while the hypocentral one is twice this value. Correlation of the seismicity with the tectonic elements indicated that most of the NW-SE oriented faults are active with strike-slip movement along this orientation and extension perpendicular to it. The neogene basins of Messini, Meligalas and Megalopolis are seismically very active and their eastern flanks are delineated by higher seismic activity than their western ones. This indicates that the basins are asymmetric with master faults defining their eastern-northeastern flanks. This hypothesis is supported by the asymmetric structure mapped at the offshore Messiniakos basin as densely spaced high resolution reflection seismic profiles have revealed. The western margins of the basins are less deformed and the seismic activity is dispersed over several minor NW-SE faults. Since the NW-SE striking faults onshore are truncated by major NE-SW oriented ones, their overall length is shortened, reducing their seismic potential and capacity to store large stresses that could produce events above Ms6.1. Offshore western Messinia, in the Ionian Sea, the size and activity of the faults is significantly larger and prone to develop events of larger magnitudes. Subcrustal seismicity indicates a deepening of the foci to the east-northeast.Part of this work was presented at the CIESM Conference, Monaco, 2001, and in the EGS General Assembly, Nice, 2001.  相似文献   

Statistical Detection and Characterization of a Deviation from the Gutenberg-Richter Distribution above Magnitude 8     

V. F. Pisarenko  D. Sornette 《Pure and Applied Geophysics》2004,161(4):839-864

— We present a quantitative statistical test for the presence of a crossover c₀ in the Gutenberg-Richter distribution of earthquake seismic moments, separating the usual power-law regime for seismic moments less than c₀ from another faster decaying regime beyond c₀. Our method is based on the transformation of the ordered sample of seismic moments into a series with uniform distribution under condition of no crossover. A simulation method allows us to estimate the statistical significance of the null hypothesis H₀ of an absence of crossover (c₀=infinity). When H₀ is rejected, we estimate the crossover c₀ using two different competing models for the second regime beyond c₀ and the simulation method. For the catalog obtained by aggregating 14 subduction zones of the Circum-Pacific Seismic Belt, our estimate of the crossover point is log(c₀)=28.14 ± 0.40 (c₀ in dyne-cm), corresponding to a crossover magnitude m_W=8.1 ± 0.3. For separate subduction zones, the corresponding estimates are substantially more uncertain, so that the null hypothesis of an identical crossover for all subduction zones cannot be rejected. Such a large value of the crossover magnitude makes it difficult to associate it directly with a seismogenic thickness as proposed by many different authors. Our measure of c₀ may substantiate the concept that the localization of strong shear deformation could propagate significantly in the lower crust and upper mantle, thus increasing the effective size beyond which one should expect a change of regime.  相似文献   

Copper (II) Speciation in a Freshwater Ecosystem     

Smolyakov  B. S.  Zhigula  M. V.  Ryzhikh  A. P.  Sinitsyna  E. V.  Ermolaeva  N. I.  Fedotova  A. A. 《Water Resources》2004,31(1):55-63

Results of chemico-biological experiments in a natural water body with the use of model systems with Cu (II) introduced in them at different proportions of its chemical forms (natural and simulated) in the solution. The model forms used in the experiments were Cu complexes with benzyl- and hexadecylmalonic acids, simulating low-molecular dissolved organic substances. The experimental conditions were chosen based on a preliminary calculation using WATEQ–4f program. The complexes of Cu with hexadecylmalonic acid are found to be absorbed by suspensions and removed into bottom sediment more actively than other Cu forms. The toxicity of introduced Cu for the phyto- and zooplanktonic communities is found to depend on the concentration of Cu²⁺ aqua-ions in the solution, in the presence of which the higher concentrations of complexes with malonic acids do not exert their toxic effect.  相似文献   

Numerical Modeling of Ice Jams     

Debol'skaya  E. I.  Derbenev  M. V.  Maslikova  O. Ya. 《Water Resources》2004,31(5):490-496

A numerical model is proposed to describe the formation of ice jams under the effect of a release wave.  相似文献   

The State of Benthic Communities and Water Quality Evaluation in the Cheboksary Reservoir   总被引：1，自引：1，他引：1  

Nazarova  L. B.  Semenov  V. F.  Sabirov  R. M.  Efimov  I. Yu. 《Water Resources》2004,31(3):316-322

Present-day quantitative and qualitative characteristics of the Cheboksary Reservoir have been investigated, and data on the biological diversity of benthic organisms have been compared to those of hydrobiological studies carried out in the region prior to the reservoir construction. The reservoir bottom communities include 75 species and forms of benthos. The reservoir water quality has been evaluated using different methods, including the determination of the degree of morphological structure abnormalities in chironomid larvae, regarded as sublethal indicators of bottom sediment pollution with toxic substances.  相似文献   

Carbon-Oxidizing and Sulfate-Reducing Bacteria in Mozhaisk Reservoir Soils     

Tkebuchava  L. F.  Komarova  T. I.  Il'inskii  V. V.  Koronelli  T. V. 《Water Resources》2004,31(5):560-564

The population and distribution of carbon-oxidizing and sulfate-reducing bacteria in the soils of the Mozhaisk Reservoir are studied.  相似文献