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Studies on composition and distribution of dust deposition are necessary for the risk assessment of dust to atmospheric quality. We studied the vertical distribution pattern of dust and metal (Cu, Fe, Pb, Zn) deposition up to 33 m height in urban environment. Integrated geochemical, mineralogical and magnetic study of the seasonally sampled dust helped to specify our knowledge on the use of magnetic susceptibility for tracking its deposition. Harmful dust and metal deposition may occur even at great heights and at the low-traffic side of buildings. Re-suspension of local surface materials dominates the dust deposition primarily in summer and spring due to weather conditions, and it may overwrite the influence of recent anthropogenic activities on dust composition. The accepted air-flow models should be modified by taking the local conditions (weather, morphology, etc.) into account. All studied metals showed strong enrichment in the dust and could be characterized by similar vertical deposition pattern to dust. The total susceptibility was found to be much more useful proxy for tracking dust and metal deposition than mass-specific susceptibility. Using the former, potential errors arising from sampling practice of settled dust could be eliminated. The most important heavy-metal-bearing phases were iron oxides and clay minerals. Their different behavior during the dust deposition is reflected by the vertical metal distribution patterns. Clay minerals originate primarily from re-suspension and may be one of the most important sources of potentially mobile heavy metals in such materials.  相似文献   
2.
Frequently, at temperatures lower than the metamorphic peak conditions, slates undergo mineral transformations, usually mediated by fluids. We have studied core material of an epizonal slate series (Szendr? Mountains, NE-Hungary) to reconstruct the post-metamorphic lower-T hydrothermal alterations using petrographic, X-ray diffraction, electron microprobe methods, and transmission electron microscopy. The borehole crosscuts an upper part of the ca. 600?C800?m Lower-Carboniferous flysch-like Szendr? Phyllite Formation. The samples were metamorphosed reaching epizonal conditions with a mineral assemblage characterized by quartz, muscovite, chlorite and albite. Even in the freshest samples, break-up and loosening of the regional metamorphic structure was observed, with cracks parallel to or crossing the cleavage. In the upper part, chlorite and albite are almost absent, while the presence of paragonite, mixed Na?CK mica, and mixed-layered minerals with smectitic component are characteristic. Goethite, halloysite, and subordinate kaolinite are present in the most altered sample (13.0?m in the profile) which may indicate the position of the fissures in which the circulation of the post-metamorphic fluids was the most intense. Muscovite is the only mica from the lower part of the profile and chlorite becomes a significant constituent, whereas paragonite, halloysite, and kaolinite are missing. Discrete smectite is present in all the samples in spite of being incompatible with the prograde evolution of the sequence. The interleaved smectite layers in chlorite and muscovite/chlorite mixed-layers show at the lattice level textural characteristics indicative of a later alteration process. After the metamorphic peak at epizonal conditions, the introduction of hot fluids through the fractures gave rise to the crystallization of Na?CK white micas and muscovite/chlorite under anchizonal conditions. In a final stage of the hydrothermal process, the cooling of the circulating fluids favored the formation of halloysite and kaolinite in the areas near to the fissures, smectites in the samples far away from the fractures, and locally, goethite. The Fe2O3 content increasing upwards indicates oxidizing conditions in the late stage of hydrothermal activity and/or eventually, an influence of a younger near-surface weathering.  相似文献   
3.
Horizontally layered (1D) earth models are often assumed as a model estimate for the interpretation of geophysical data measured along 2D geological structures. In this process, the individual data sets are usually inverted independently, and it is considered only in a later phase of interpretation that these local (1D) models have common characteristic features. Taking account of these common attributes, instead of the successive independent interpretations, the lateral variations of geometrical and petrophysical parameters can be efficiently determined for the whole 2D structure by applying a series expansion. Using global basis functions, two advantages can be achieved: (i) choosing an appropriate number of basis functions helps us to restrict the complexity of the model; (ii) the integration of all the data sets measured along the profile gives rise to the application of simultaneous or joint inversion methods. This results in a decrease of the number of independent unknowns, a higher stability during the inversion and a more accurate and reliable parameter estimation.In this paper, a joint inversion algorithm is presented using DC geoelectric apparent resistivities and refraction seismic travel times measured along various layouts above a 2D geological model. To describe lateral variations series, expansions are used, and furthermore, to improve the often used approximation of a (locally) 1D forward modelling, the integral mean value of the horizontally changing model parameters (calculated along an appropriately defined interval) is introduced. We call the inversion procedure that combines series expansions and the concept of integral mean Generalised Series Expansion (GSE) inversion. The method was developed and tested for both the simultaneous (integrating data sets of one method or methods on the same physical basis) and the joint inversion (where data sets of methods on different physical bases are joined together), using synthetic and field data sets. It is also demonstrated that the equivalence problem inherent in the independent inversion of DC geoelectric data can efficiently be resolved by the use of the joint GSE inversion method in the cases of conductive and resistive equivalent geological models.  相似文献   
4.
Summary Mean directions of magnetization (29 normal and 31 reversed) were recorded for 60 magmatic localities of middle Miocene age from the Börzsöny Mountains (Hungary). The overall mean direction of RM, irrespective of polarity, isD=0,9°;I=59,8°; withk=8,3 and 95=6,8°. The coordinates of the corresponding geomagnetic north pole are =82,7°, A=193,8 with p=7,7° and m=10,2°.  相似文献   
5.
High-resolution transmission electron microscopy was applied for the detailed nanostructural investigation of Popigai impact diamonds with the aim of revealing the nature of the amorphous carbon of the matrix. The successful application of two complementary specimen preparation methods, focused ion beam (FIB) milling and mechanical cleavage, allowed direct imaging of nanotwinned nanodiamond crystals embedded in a native amorphous carbon matrix for the first time. Based on its stability under the electron beam, native amorphous carbon can be easily distinguished from the amorphous carbon layer produced by FIB milling during specimen preparation. Electron energy loss spectroscopy of the native amorphous carbon revealed the dominance of sp 2-bonded carbon and the presence of a small amount of oxygen. The heterogeneous size distribution and twin density of the nanodiamond crystals and the structural properties of the native amorphous carbon are presumably related to non-graphitic (organic) carbon precursor material.  相似文献   
6.
The Pannonian Basin is a deep intra-continental basin that formed as part of the Alpine orogeny. In order to study the nature of the crustal basement we used the long-wavelength magnetic anomalies acquired by the CHAMP satellite. The anomalies were distributed in a spherical shell, some 107,927 data recorded between January 1 and December 31 of 2008. They covered the Pannonian Basin and its vicinity. These anomaly data were interpolated into a spherical grid of 0.5° × 0.5°, at the elevation of 324 km by the Gaussian weight function. The vertical gradient of these total magnetic anomalies was also computed and mapped to the surface of a sphere at 324 km elevation. The former spherical anomaly data at 425 km altitude continued downward to 324 km. To interpret these data at the elevation of 324 km we used an inversion method. A polygonal prism forward model was used for the inversion. The minimum problem was solved numerically by the Simplex and Simulated annealing methods; a L2 norm in the case of Gaussian distribution parameters and a L1 norm was used in the case of Laplace distribution parameters. We interpret that the magnetic anomaly was produced by several sources and the effect of the sable magnetization of the exsolution of hemo-ilmenite minerals in the upper crustal metamorphic rocks.  相似文献   
7.
Éva Kis 《GeoJournal》1995,36(2-3):151-156
The granulometric analysis of loess varieties is meant to contribute to the subdivision of loess sequences, to the reconstruction of the environments of loess formation (identifying areas of loess origin [from where the dust derives], geographical obstacles to transport, contemporary wind directions [through drawing isokatharoses lines connecting points with identical FG values] and even wind velocities) and subsequent changes in climatic and geographical conditions. It was investigated whether loesses and loess-like deposits can be described by a generalised grain size parameter (fineness grade, FG) or to what extent other granulometric indices can lead to a more differentiated picture of grain size variation. Fineness grade was used to denominate sediments and to identify finer and coarser sections in the series;K d index indicates the lithostratigraphical positions of cold stages (maximum values) and warm stages (minimum values); finesorting (S o) points to eolian accumulation, while fluvial deposits (bedload, saltated and suspended load) are poorly sorted;kurtosis (K) allows conclusions for the reworking of the deposit andasymmetry (Sk) indicates the factor active in the accumulation of the deposit.The paper concentrates primarily on the study of variation in the vertical profile of deposits. Along with other indices, fineness grade was found useful in distinguishing between loess varieties and other sediments and could even replace the function of the conventional index median value (Md).  相似文献   
8.
ABSTRACT

The impact of climate change on runoff characteristics is investigated for the Upper Tisza basin, in eastern Central Europe. For a reliable estimation of uncertainty, an appropriate stochastic weather generator is embedded into a Monte Carlo cycle capable of generating any large number of independent, equally probable, 100-year-long daily sequences of synthetic data with which a hydrological model is driven in order to obtain the hydrological responses to the meteorological data sequences. According to our results, a decrease of daily average runoff is likely to occur in the future in the Upper Tisza basin, especially in July and August. The occurrence of water levels below the critical low level is estimated to increase between July and October. Level-3 flood warnings are projected to be less frequent in the future; however, they will tend to be more severe than in the historical period.  相似文献   
9.
A new array type, i.e., the γ11n arrays, is introduced in this paper, in which the sequence of the current (C) and potential (P) electrodes is CPCP, and the distance between the last two electrodes is n times the distance between the first two ones and that of the second one and the third one. These arrays are called quasinull arrays because they are—according to their array and behaviour—between the traditional and null arrays. It is shown by numerical modelling that, in detecting small‐effect inhomogeneity, these configurations may be more effective than the traditional ones, including the optimized Stummer configuration. Certain γ11n configurations—especially the γ112, γ113, and γ114—produced better results both in horizontal and vertical resolution investigations. Based on the numerical studies, the γ11n configurations seem to be very promising in problems where the anomalies are similar to the numerically investigated ones, i.e., they can detect and characterize, e.g., tunnels, caves, cables, tubes, abandoned riverbeds, or discontinuity, in a clay layer with greater efficacy than those of the traditional configurations. γ11n measurements need less data than traditional configurations; therefore, the time demand of electrical resistivity tomography measurements can be shortened by their use.  相似文献   
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