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181.
Hitoshi Morikawa Sumio Sawada Kenzo Toki Kunio Kawasaki 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):821-828
In order to discuss the relationship between the lower and higher frequency components of earthquake source spectra, we deal with impulse train model as source time function of earthquake, because spectral characteristics of source time function depend on occurrence times of impulse function which corresponds to small extent on the fault. Then, the spectral characteristics of source time function are obtained analytically and numerically from the stochastic viewpoints: namely, on one hand, the trend of impulse train dominates the frequency characteristics in low frequency range, and on the other hand, the fluctuation from the trend settles high frequency range. Furthermore, it is shown that the spectral properties of source time function can be determined using only two parameters which are number of impulses n and the probability density function of occurrence time of impulses fT(t). 相似文献
182.
Takashi Tomiyasu Akito Matsuyama Ryusuke Imura Hitoshi Kodamatani Junko Miyamoto Yuriko Kono David Kocman Jo?e Kotnik Vesna Fajon Milena Horvat 《Environmental Earth Sciences》2012,65(4):1309-1322
Although the mining activity of the Idrija mine in Slovenia ceased in 1995, a large amount of mining dregs containing high
concentrations of mercury remains in the area. The mining dregs were transported with river flow and deposition along the
Idrija River. To estimate the dispersion and change in the chemical form of mercury, a total of 28 soil core samples were
taken around the river. The individual core samples were separated into layers for the analysis of their chemical composition,
carbon contents, total mercury (T-Hg) and methylmercury (MeHg) concentrations. The chemical composition measured by X-ray
fluorescence spectrometry was useful to estimate the dispersion of tailings: the fluvial terrace soil had a chemical composition
similar to that of the tailings and could be distinguished clearly from the forest soil. The highest T-Hg concentration, 1,100 mg kg−1, was observed in the fluvial terrace soil near the mine. Although the concentration decreased gradually along with distance
from the mine, concentrations higher than 200 mg kg−1 of T-Hg were still observed in the fluvial terrace soil approximately 20 km downstream from the mine. In the vertical distribution
of T-Hg in the hillslope soil, a higher value was observed in the upper layers, which suggests the recent atmospheric deposition
of mercury. The concentration of MeHg was the lowest at the riverside and higher in the hillslope soil, which was the opposite
of the T-Hg distribution. The total organic carbon content tracked similarly with the distribution of MeHg and a linear relation
with a significantly high correlation coefficient was obtained. The distinction may be related to the different dispersion
process of mercury, and the organic carbon contents may be an important factor for MeHg formation. 相似文献
183.
Philippe Blanc Hélène Gailhanou Jacques Rogez Georges Mikaelian Hitoshi Kawaji Fabienne Warmont Stéphane Gaboreau Sylvain Grangeon Jean-Marc Grenèche Philippe Vieillard Claire I. Fialips Eric Giffaut Eric C. Gaucher F. Claret 《Physics and Chemistry of Minerals》2014,41(8):603-615
In the context of the deep waste disposal, we have investigated the respective stabilities of two iron-bearing clay minerals: berthierine ISGS from Illinois [USA; (Al0.975FeIII0.182FeII1.422Mg0.157Li0.035Mn0.002)(Si1.332Al0.668)O5(OH)4] and chlorite CCa-2 from Flagstaff Hill, California [USA; (Si2.633Al1.367)(Al1.116FeIII0.215Mg2.952FeII1.712Mn0.012Ca0.011)O10(OH)8]. For berthierine, the complete thermodynamic dataset was determined at 1 bar and from 2 to 310 K, using calorimetric methods. The standard enthalpies of formation were obtained by solution-reaction calorimetry at 298.15 K, and the heat capacities were measured by heat-pulse calorimetry. For chlorite, the standard enthalpy of formation is measured by solution-reaction calorimetry at 298.15 K. This is completing the entropy and heat capacity obtained previously by Gailhanou et al. (Geochim Cosmochim Acta 73:4738–4749, 2009) between 2 and 520 K, by using low-temperature adiabatic calorimetry and differential scanning calorimetry. For both minerals, the standard entropies and the Gibbs free energies of formation at 298.15 K were then calculated. An assessment of the measured properties could be carried out with respect to literature data. Eventually, the thermodynamic dataset allowed realizing theoretical calculations concerning the berthierine to chlorite transition. The latter showed that, from a thermodynamic viewpoint, the main factor controlling this transition is probably the composition of the berthierine and chlorite minerals and the nature of the secondary minerals rather than temperature. 相似文献
184.
Environmentally friendly options for restoring limestone using microorganisms have attracted recent attention. The governing principle of this technique is to use the metabolism of microorganisms to precipitate carbonate in the gaps of mineral particles; this process is known as microbial carbonate precipitation (MCP). Here, an outcrop associated with MCP under natural conditions at the Giza cliff in Okinawa, Japan was investigated. Colonies of photoautotrophic microorganisms containing chlorophyll were found inhabiting a layer of limestone 2–4 mm below the surface of the outcrop. These microorganisms survived and photosynthesised within the limestone under favorable conditions that include an effective photon flux density of 15–75 µmol/m2/s, and some fresh calcium carbonates (i.e., calcite) were precipitated around the cell walls and extracellular polymeric substances (EPS) of the microorganisms. Furthermore, the results of powder X-ray diffraction (XRD) suggest that the synthetic calcite within the limestone may improve the mechanical strength of the outcrop. These in situ and laboratory findings indicate that these microbial functions may be applicable to some weathered rock surfaces as a self-organizing surface protection and conservation technology. 相似文献