Source apportionment of trace metals in surface waters of a polluted stream using multivariate statistical analyses   总被引：16，自引：0，他引：16  

Pekey H  Karakaş D  Bakoğlu M 《Marine pollution bulletin》2004,49(9-10):809-818

Surface water samples were collected from ten previously selected sites of the polluted Dil Deresi stream, during two field surveys, December 2001 and April 2002. All samples were analyzed using ICP-AES, and the concentrations of trace metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Pb, Sn and Zn) were determined. The results were compared with national and international water quality guidelines, as well as literature values reported for similar rivers. Factor analysis (FA) and a factor analysis-multiple regression (FA-MR) model were used for source apportionment and estimation of contributions from identified sources to the concentration of each parameter. By a varimax rotated factor analysis, four source types were identified as the paint industry; sewage, crustal and road traffic runoff for trace metals, explaining about 83% of the total variance. FA-MR results showed that predicted concentrations were calculated with uncertainties lower than 15%.  相似文献   

Site amplification at Avcılar, Istanbul     

M. Ergin  S. zalaybey  M. Aktar  M.N. Yalin 《Tectonophysics》2004,391(1-4):335

Avcılar is the suburb of Istanbul that was most heavily damaged during the August 17, 1999 M_w 7.4 Izmit earthquake. Strong ground motion caused fatalities and damage in Avcılar despite being 90 km from the epicenter. We deployed five portable seismograph stations equipped with Reftek 24-bit recorders and L4C-3D seismometers for 2 months, in order to understand why the local site response was different from elsewhere in Istanbul. A reference station was placed on a hard rock site, and the remaining four stations were placed on other geological units, in areas that had experienced varying levels of damage. We calculated frequency-dependent ground amplification curves by taking the ratios of the spectra at soft and hard rock sites. We obtained similar site response curves for most earthquakes at each site in the frequency range of 0.3–1.6 Hz, and observed no significant site amplification beyond 2.0 Hz at any site. The overall characteristics of the recorded S-waveforms and our modeling of the calculated site amplification curves are consistent with amplification as a result of trapping of seismic energy within a 100–150 m thick, low-velocity subsurface layer. We also review the applicability of microtremor measurements to estimate local site effects at Avcılar. For these data, we used ratios of spectra of horizontal to vertical components to obtain each site response. These results are compared with standard spectral ratios. These microtremor measurements provide consistent estimates of the amplification at most sites at the higher end of the frequency band, namely above 1 Hz. The results from both methods indeed agree well in this part of the frequency band. However, the microtremor method fails to detect amplification at lower frequencies, namely <1.0 Hz.  相似文献   

The Misis–Andırın Complex: a Mid-Tertiary melange related to late-stage subduction of the Southern Neotethys in S Turkey     

Alastair Robertson  Ülvi Can Unlügen  Nurdan nan  Kemal Ta li 《Journal of Asian Earth Sciences》2004,22(5):413

The Mid-Tertiary (Mid-Eocene to earliest Miocene) Misis–Andırın Complex documents tectonic-sedimentary processes affecting the northerly, active margin of the South Tethys (Neotethys) in the easternmost Mediterranean region. Each of three orogenic segments, Misis (in the SW), Andırın (central) and Engizek (in the NE) represent parts of an originally continuous active continental margin. A structurally lower Volcanic-Sedimentary Unit includes Late Cretaceous arc-related extrusives and their Lower Tertiary pelagic cover. This unit is interpreted as an Early Tertiary remnant of the Mesozoic South Tethys. The overlying melange unit is dominated by tectonically brecciated blocks (>100 m across) of Mesozoic neritic limestone that were derived from the Tauride carbonate platform to the north, together with accreted ophiolitic material. The melange matrix comprises polymict debris flows, high- to low-density turbidites and minor hemipelagic sediments.The Misis–Andırın Complex is interpreted as an accretionary prism related to the latest stages of northward subduction of the South Tethys and diachronous continental collision of the Tauride (Eurasian) and Arabian (African) plates during Mid-Eocene to earliest Miocene time. Slivers of Upper Cretaceous oceanic crust and its Early Tertiary pelagic cover were accreted, while blocks of Mesozoic platform carbonates slid from the overriding plate. Tectonic mixing and sedimentary recycling took place within a trench. Subduction culminated in large-scale collapse of the overriding (northern) margin and foundering of vast blocks of neritic carbonate into the trench. A possible cause was rapid roll back of dense downgoing Mesozoic oceanic crust, such that the accretionary wedge taper was extended leading to gravity collapse. Melange formation was terminated by underthrusting of the Arabian plate from the south during earliest Miocene time.Collision was diachronous. In the east (Engizek Range and SE Anatolia) collision generated a Lower Miocene flexural basin infilled with turbidites and a flexural bulge to the south. Miocene turbiditic sediments also covered the former accretionary prism. Further west (Misis Range) the easternmost Mediterranean remained in a pre-collisional setting with northward underthrusting (incipient subduction) along the Cyprus arc. The Lower Miocene basins to the north (Misis and Adana) indicate an extensional (to transtensional) setting. The NE–SW linking segment (Andırın) probably originated as a Mesozoic palaeogeographic offset of the Tauride margin. This was reactivated by strike-slip (and transtension) during Later Tertiary diachronous collision. Related to on-going plate convergence the former accretionary wedge (upper plate) was thrust over the Lower Miocene turbiditic basins in Mid–Late Miocene time. The Plio-Quaternary was dominated by left-lateral strike-slip along the East Anatolian transform fault and also along fault strands cutting the Misis–Andırın Complex.  相似文献   

Structural and Geomorphological Aspects of the Kat Landslides (Tokat—Turkey) and Susceptibility Mapping by Means of GIS     

Işik Yilmaz  Mustafa Yildirim 《Environmental Geology》2006,50(6):931-931

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An experimental study of a midbroken 2-bay, 6-storey reinforced concrete frame subject to earthquakes     

P.S. Skjærbæk  B. Ta?kin  P.H. Kirkegaard  S.R.K. Nielsen 《Soil Dynamics and Earthquake Engineering》1997,16(6):373-384

A 2-bay, 6-storey model test reinforced concrete frame (scale l:5) subjected to sequential earthquakes of increasing magnitude is considered in this paper. The frame was designed with a weak storey, in which the columns are weakened by using thinner and weaker reinforcement bars. The aim of the work is to study the global response to a damaging strong motion earthquake event of such buildings. Special emphasis is put on examining to what extent damage in the weak storey can be identified from global response measurements during an earthquake where the structure survives, and what level of excitation is necessary in order to identify the weak storey. Furthermore, emphasis is put on examining how and where damage develops in the structure and especially how the weak storey accumulates damage. Besides the damage in each storey the structure is identified by a static load at the top storey while measuring the horizontal displacement of the stories and also visual inspection is performed. From the investigations it is found that the reason for failure in the weak storey is that the absolute value of the stiffness deteriorates to a critical value where large plastic deformations occur and the storey is not capable of transferring the shear forces from the storeys above so failure is unavoidable.  相似文献   

The effect of the coarse aeolian sand on siltation of the Inner Mongolian Reach of the Yellow River     

Wanquan Ta  Gensheng Yang  Jianjun Qu  Tao Wang  Fennian Dai 《Environmental Geology》2003,43(5):493-502

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Daily pan evaporation modelling using multi‐layer perceptrons and radial basis neural networks     

Özgür Kişi 《水文研究》2009,23(2):213-223

This paper reports on investigations of the abilities of three different artificial neural network (ANN) techniques, multi‐layer perceptrons (MLP), radial basis neural networks (RBNN) and generalized regression neural networks (GRNN) to estimate daily pan evaporation. Different MLP models comprising various combinations of daily climatic variables, that is, air temperature, solar radiation, wind speed, pressure and humidity were developed to evaluate the effect of each of these variables on pan evaporation. The MLP estimates are compared with those of the RBNN and GRNN techniques. The Stephens‐Stewart (SS) method is also considered for the comparison. The performances of the models are evaluated using root mean square errors (RMSE), mean absolute error (MAE) and determination coefficient (R²) statistics. Based on the comparisons, it was found that the MLP and RBNN computing techniques could be employed successfully to model the evaporation process using the available climatic data. The GRNN was found to perform better than the SS method. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Influence of matric suction on shear strength behavior of a residual clayey soil   总被引：2，自引：0，他引：2  

C. Kayadelen  M. A. Tekinsoy  T. Taşkıran 《Environmental Geology》2007,53(4):891-901

In this paper, the shear strength with respect to the matric suction of unsaturated soils was studied. For this purpose, unsaturated triaxial testing procedures were applied to the undisturbed residual soil specimens. An apparatus for performing triaxial tests was designed and constructed. In the tests, matric suction was controlled by using the axis translation technique, and pore water volume changes were measured by means of a volume change transducer with 10⁻⁸ m³ sensitivity. The test results indicated that the matric suction contributes to the shear strength of unsaturated soil specimens, and this contribution called suction strength varies non-linearly with respect to the matric suction. The logarithmic model needing to know the air-entry value and the internal friction angle of a soil specimen for prediction of the suction strength were presented and compared with the test results. It was found that suction strength values predicted from the proposed model were in satisfactory agreement with the experimental results.  相似文献   

Estimation of Rock Cuttability from Shore Hardness and Compressive Strength Properties   总被引：6，自引：1，他引：6  

D. Tumac  N. Bilgin  C. Feridunoglu  H. Ergin 《Rock Mechanics and Rock Engineering》2007,40(5):477-490

Summary Shore hardness has been used to estimate some mechanical and physical properties of rocks for many years. This study differs from previous studies in a way that it is directly oriented to rock cuttability. Two Shore hardness values (SH ₁ andSH ₂) and a coefficient of deformation value (K) have been measured for 30 different rock samples. In the first stage of the study, optimum specific energy values for 16 different rock samples obtained from full-scale cutting tests were correlated with the Shore hardness values of the same rock samples changingSH ₁ values from 9 to 66 andSH ₂ values from 25 to 83, with deformation coefficient values changing from 26 to 195. In the second stage, the performance of a roadheader used in the Kü?üksu (Istanbul) tunnel was recorded in detail and the instantaneous cutting rate of the machine was determined. Then, the relationship between Shore hardness values, deformation coefficient and the instantaneous cutting rate of the machine was determined for different formations encountered. It is concluded that there is a relationship between Shore hardness values, optimum specific energy and compressive strength, which may be used to estimate the rock cuttability and the instantaneous cutting rates of roadheaders within certain limits of reliability.  相似文献   

Geotechnical evaluation of Miocene gypsum from Sivas (Turkey)   总被引：2，自引：0，他引：2  

Ergun Karacan  Işik Yilmaz 《Geotechnical and Geological Engineering》2000,18(2):79-90

Gypsum is widely distributed in Sivas (Turkey), occurring chiefly in the formations of Miocene age. The gypsum is generally of the alabastrine type with a little of the porphiroblast type and contains traces of clay minerals, anhydrite and calcite. It is a moderately strong rock in terms of its unconfined compressive strength which is related to the crystal size. Strength increases as the crystal size decreases. The strength of gypsum was reduced by approximately 55%, when the samples were kept in the water for 20 days. Most samples exhibit plastic–elastic–plastic deformation. The gypsum has a high modulus ratio, and is a moderately deformable rock. High lateral deformations and low vertical deformations are observed under the vertical stress conditions in accordance with the relationship between modulus ratio and strain.  相似文献