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排序方式: 共有114条查询结果,搜索用时 46 毫秒
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Gökhan Göktürkler Çağlayan Balkaya Zülfikar Erhan Ayça Yurdakul 《Environmental Geology》2008,54(6):1283-1290
Near-surface geophysical methods are commonly used to solve a wide class of geological, engineering and environmental problems. In this study, a geoelectrical survey was performed to investigate an alluvial aquifer. The study area is located in the southwest of the Çubukluda? graben, situated in the south of ?zmir, Turkey. The geophysical studies included the electrical resistivity imaging and self-potential (SP) methods. The resistivity data were acquired along eight profiles in the northern part of the study area by a Wenner-Schlumberger electrode configuration and the data processing was achieved by a tomographic inversion technique. The SP data were collected by gradient technique along 16 profiles. Total field values were calculated for each profile by addition of the successive gradient values, then a total field SP map was obtained. The water-saturated zone in the northern part of the study area was clearly revealed by the electrical resistivity imaging and the SP survey yielded useful information on the subsurface fluid movement. 相似文献
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Temporal variations of fluoride concentration in Isparta public water system and health impact assessment (SW-Turkey) 总被引:1,自引:0,他引:1
Water–rock interaction is one of the prime factors affecting the fluoride contents of surface and groundwater. If fluoride
concentration of drinking water has been neglected, excess fluoride can cause serious dental and medical problems on human
health, which is well known at Golcuk-Isparta region. In the research area, Egirdir lake, Golcuk lake and surrounding springs
have been utilized as drinking water sources. Golcuk lake water and surrounding groundwaters have high fluoride content (1.4–4.6 mg/l),
which is above the WHO standards. Fluoride is predominantly supplied by dissolution of fluoride within the fluormicas of volcanics
during the circulation of water. Fluoride concentrations of waters have shown variations for dry and rainy seasons depending
on the degree of interaction between groundwater and volcanic rocks. It tends to decrease in rainy seasons and increase in
dry seasons for all years. In this study, temporal variations and spatial distribution of fluoride concentration in public
water system of Isparta were investigated to get benefit using GIS techniques from1990 to 2003 years. Extremely fluoride concentrations
were measured in the public water system in 1990 at almost every district of the city. In 2003, fluoride content of the public
water system decreased in some district of city due to drinking water has started obtaining from Egirdir lake in 1995. The
fluoride contents of Isparta drinking water ought to be modified with suitable mixture of lake waters and groundwater point
of view to health impact. 相似文献
24.
A comparison of the contribution of zooplankton and nekton taxa to the near-surface acoustic structure of three Turkish seas 总被引:1,自引:0,他引:1
Erhan Mutlu 《Marine Ecology》2005,26(1):17-32
The bioacoustics of upper waters of the Black Sea, the Sea of Marmara, and the Mediterranean Sea were studied in October 1999 with an echosounder with 120 and 200 kHz dual‐beam transducers. Net tows were taken to ground‐truth the acoustic volume backscattering. A forward solution was applied to determine significant scatterers of the three seas with regard to detection limits of the frequencies and background noise measured in each sea. The noise was 4 dB higher in the Sea of Marmara than in the other two seas. 200 kHz data showed significant correlation between measured and calculated volume backscattering strength, and density (biomass and abundance) of the taxa. Large‐sized copepods and chaetognaths in the Black Sea, Aurelia, Beroe, chaetognaths and large‐sized and abundant appendicularians in the Sea of Marmara, and fish larvae in the Mediterranean Sea contributed most to the volume backscattering. 相似文献
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Historical earthquake activity of the northern part of the Dead Sea Fault Zone, southern Turkey 总被引:1,自引:0,他引:1
H. Serdar Akyuz Erhan Altunel Volkan Karabacak C. Caglar Yalciner 《Tectonophysics》2006,426(3-4):281-293
The northern part of the Dead Sea Fault Zone is one of the major active neotectonic structures of Turkey. The main trace of the fault zone (called Hacıpaşa fault) is mapped in detail in Turkey on the basis of morphological and geological evidence such as offset creeks, fault surfaces, shutter ridges and linear escarpments. Three trenches were opened on the investigated part of the fault zone. Trench studies provided evidence for 3 historical earthquakes and comparing trench data with historical earthquake records showed that these earthquakes occurred in 859 AD, 1408 and 1872. Field evidence, palaeoseismological studies and historical earthquake records indicate that the Hacıpaşa fault takes the significant amount of slip in the northern part of the Dead Sea Fault Zone in Turkey. On the basis of palaeoseismological evidence, it is suggested that the recurrence interval for surface faulting event is 506 ± 42 years on the Hacıpaşa fault. 相似文献
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A continuum model is developed to predict the response of multi-storey frames to dynamic excitations. The equations of the proposed theory are derived in a systematic manner using smoothing operations. The order of the theory is kept arbitrary. To appraise the validity of the theory natural frequencies and vibration shapes predicted by discrete and continuum models are compared. This comparison provides valuable information about goodness of the proposed model because natural frequencies and vibration shapes represent spectral structure of the theory. The most crucial finding obtained from the analysis is that, as an implication of the smoothing operations used in the derivation of the theory, one should define an effective height which is equal to the height of the frame plus half of the height of the top storey. The numerical results indicated that the use of effective height in the analysis improves the prediction of the theory considerably. It is found also that the number of modes the continuum model can describe correctly increases with the number of storeys and that the lowest number of storeys for which the theory can be used is three. Further, it is observed that an increase in the order of the theory improves greatly its prediction and that in the presence of non-uniform distributions of frame properties, such as, of mass, stiffness, etc., the theory still remains valid. 相似文献
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In this study, two different historical structures built in Trabzon have been processed by ambient vibrations and seismic refraction measurements. One of the investigated historical structures is the Atatürk Pavilion built in the nineteenth century, and the other one is Hagia Sophia which was built in the thirteenth century. These two buildings are among the most important historical buildings in Trabzon and are very important for the tourism of the city. In order to determine peak/s frequency and amplitude from the horizontal-to-vertical spectral ratios (HVSRs), we have performed several measurements of ambient vibrations both inside (at different floors) and outside (on the ground) of structures. We have also conducted seismic prospecting to evaluate the vertical 1D and 2D profile of longitudinal and shear seismic waves, Vp and Vs, respectively. To this purpose, we have performed seismic refraction tomography and MASW. Ambient vibrations and seismic measurements were compared with each other. The results show that average predominant frequencies and HVSR amplitudes of inside and outside of Atatürk Pavilion are 4.0 Hz, 7.8 Hz and 2.6, 2.3, respectively. The Vp values vary from 300 to 2070 m/s, and the Vs for maximum effective depth is up to 790 m/s in Atatürk Pavilion. On the other hand, average predominant frequencies and HVSR amplitudes of inside and outside of Hagia Sophia and its tower are 4.7, 4.4 and 2.4 Hz and 1.6, 1.8 and 6.9, respectively. Vp values range from 450 to 2200 m/s, and Vs for maximum effective depth is also up to 1000 m/s in Hagia Sophia. The frequency values (F0?=?Vs/4 h) calculated from the velocities up to the maximum effective depth for Atatürk Pavilion are in good agreement with the predominant frequency values determined from ambient vibrations. Atatürk Pavilion and Hagia Sophia soils have been classed according to Eurocode 8 by using VS30 values. The class was defined as “B.” Moreover, the bedrock in studied area is basalt. The high Vp and Vs values are also compatible with the lithology. The HVSR curves measured at the Hagia Sophia show the presence of clear peaks when compared to the Atatürk Pavilion. At the same time, there are marked velocity changes in the Vs sections calculated in both areas. As a result, in both areas there are significant impedance contrasts in the subsoil. However, this impedance contrast is more evident in Hagia Sophia. This could be also compatible with a lithological transition. The possible soil–structure interaction was investigated by using all the results and evaluated in terms of resonance risk. It is thought that the probability of resonance risk at Atatürk Pavilion is low according to the ambient vibrations measurements. However, resonance risk should be taken into consideration at Hagia Sophia site since the predominant frequency values are very close to each other. Finally, this site should be investigated in detail and necessary precautions should be taken against the risk of resonance. 相似文献