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42.
Geoelectrical and hydrochemical investigations for characterizing the salt water intrusion in the Khanasser valley, northern Syria 总被引：1，自引：1，他引：0
An integrated approach of geoelectrical and hydrochemical investigation surveys was proposed for indicating contact regions between saline and fresh groundwater in the Khanasser valley region, northern Syria. The qualitative and quantitative interpretations of 34 vertical electrical soundings (VES) enable to characterize the salt water intrusion laterally and vertically. The established iso-apparent resistivity maps for different AB/2 spacings obviously indicate the presence of a lowresistivity (less than 4 Ohm·m) zone related to the salt water intrusion in the Quaternary and Paleogene deposits. The different hydrochemical and geophysical parameters, such as electrical resistivity, total dissolved solids (TDS) and major ions concentrations used to characterize the salt water intrusion gave almost similar results in locating and mapping the different boundaries of the groundwater salinity. The proposed approach is useful for mapping the interface between different groundwater qualities, and can be therefore used to successfully characterize the salt water intrusion phenomenon in other semi-arid regions. The application of such an approach is a powerful tool and can be used for water resource management in the water scarce areas. 相似文献
43.
Estimating phosphorus leachability in reconstructed soil columns using HYDRUS-1D model 总被引：1，自引：1，他引：0
Abdirashid Elmi Joumana S. Abou Nohra Chandra A. Madramootoo William Hendershot 《Environmental Earth Sciences》2012,65(6):1751-1758
Modern agricultural production uses phosphorus (P) extensively to meet the challenges of feeding rapidly growing population
and changing lifestyles, making P a leading source of impairment for rivers and streams in Canada. Developing effective management
strategies to reduce P losses from agro-ecosystems requires improved understanding of P transport pathways in the soil. The
purpose of this study was to investigate vertical distribution and transport processes of phosphate (PO4) in reconstructed soil columns using HYDRUS-1D model. Results obtained from field experiments were used to calibrate and
validate the HYDRUS-1D model. The results showed that 98% of the total P applied was concentrated in the top 0.2 m of the
columns, and decreased progressively with soil depth. The model over-predicted PO4 adsorption, leading to a weak correspondence between the simulated and the measured results for PO4. This is a suggestion that the HYDRUS-1D model could not account accurately for the different soil structures found in the
undisturbed soil columns and the preferential flow that occurs in these columns. This may be due to the fact that Freundlich
isotherm, which is part of the transport equations, could not adequately describe PO4 adsorption onto the soil particles. 相似文献
44.
Damien Closson Najib Abou Karaki Musa Jad Hussein Hassan Al-Fugha André Ozer Abdullah Mubarak 《Comptes Rendus Geoscience》2003,335(12):869-879
The Dead Sea shore is affected by major subsidence and sinkholes hazards due to the decrease of the sea level. The frequency of resulting accidents increased during the last four decades. Those phenomena could be at the origin of the catastrophic destruction of a major salt evaporation pond on 22 March 2000. In this paper, we show the main results of eight years of research in gravimetry and radar interferometry devoted to identify potentially hazardous areas, at different scales along the Jordanian Dead Sea coast, from the metric scale (gravimetric approach) to the kilometric one (interferometric approach). To cite this article: D. Closson et al., C. R. Geoscience 335 (2003). 相似文献
45.
Saïdou Madougou Frederique Saïd Bernard Campistron Marie Lothon Cheikh F. Kebe 《Acta Geophysica》2012,60(5):1413-1453
We use two series of eight-month UHF radar observations collected during the dry and wet seasons of AMMA field campaign. The
ultimate goal is to do preliminary work to know whether the lowest layers are suitable for wind energy applications. Surface
wind is usually weak in West Africa, but the regular occurrence of a nocturnal low level jet (NLLJ) could provide interesting
conditions for wind energy. This work is two-fold: it first aims at improving our knowledge about the NLLJ in West Africa
regarding its structure and its variability during the year. Then, special attention is paid to the first 200 m agl, to study
the possibility to use the sub-jet wind as a source of energy. A set of enhanced radio-soundings is taken to help to understand
the dynamics and thermodynamics and to find a way to extrapolate the wind at low level, where the UHF radars do not provide
data. 相似文献
46.
Y. Klinger J. P. Avouac N. Abou Karaki L. Dorbath D. Bourles J. L. Reyss 《Geophysical Journal International》2000,142(3):755-768
The Araba valley lies between the southern tip of the Dead Sea and the Gulf of Aqaba. This depression, blanketed with alluvial and lacustrine deposits, is cut along its entire length by the Dead Sea fault. In many places the fault is well defined by scarps, and evidence for left-lateral strike-slip faulting is abundant. The slip rate on the fault can be constrained from dated geomorphic features displaced by the fault. A large fan at the mouth of Wadi Dahal has been displaced by about 500 m since the bulk of the fanglomerates were deposited 77–140 kyr ago, as dated from cosmogenic isotope analysis (10 Be in chert) of pebbles collected on the fan surface and from the age of transgressive lacustrine sediments capping the fan. Holocene alluvial surfaces are also clearly offset. By correlation with similar surfaces along the Dead Sea lake margin, we propose a chronology for their emplacement. Taken together, our observations suggest an average slip rate over the Late Pleistocene of between 2 and 6 mm yr−1 , with a preferred value of 4 mm yr−1 . This slip rate is shown to be consistent with other constraints on the kinematics of the Arabian plate, assuming a rotation rate of about 0.396° Myr−1 around a pole at 31.1°N, 26.7°E relative to Africa. 相似文献
47.
Ibrahim M. Korrat Ali A. Gharib Kamal A. Abou Elenean Hesham M. Hussein Mohamed N. El Gabry 《Acta Geophysica》2008,56(2):344-356
Seismic discriminants based on the spectral seismogram and spectral magnitude techniques have been tested to discriminate
between three events; a nuclear explosion which took place in Lop Nor, China with m
b
6.1 and two earthquakes from the closest area with m
b
5.5 and 5.3, respectively. The spectral seismogram of the three events shows that the frequency content of the nuclear explosion
differs from that of the earthquakes where the P wave is richier in high frequency content in the nuclear explosion than the corresponding earthquakes. It is also observed
that the energy decays more rapidly for the nuclear explosion than for the earthquakes. Furthermore, the spectral magnitudes
reveal significant differences in the spectra between the nuclear explosion and the two earthquakes. The observed differences
appear to be quite enough to provide a reliable discriminant. The estimated stress drop from the magnitude spectra indicates
a higher stress drop of the nuclear explosion relative to the earthquakes of the same tectonic region. 相似文献
48.
The Western Desert of Egypt is an area of natural expansion for agricultural, industrial, and civil activities. This expansion has led to a great demand for groundwater. In the central part of Egypt, on the western limestone plateau, vertical electrical sounding and borehole geophysical logging were conducted to delineate aquifer boundaries. The measurements were interpreted using the lithological information from the drilled wells as a constraining factor. Fractured chalky limestone sediments represent the main aquifer, which is covered by sand and gravel deposits and which rests directly on partially saturated and highly resistive massive limestone. Discontinuous clay layers, which overlie the aquifer unit, were detected in the southern part of the study area as well as a relatively thin marly limestone layer in the northern part. The integrated analyses carried out represent a significant and cost-effective method for delineating the main aquifer in this area. In turn, future well locations can be placed with more confidence than before, in accordance with the evaluation of the potentiality of the groundwater aquifers in the area. Although the groundwater is normally brackish, it can serve the acute demands for water, especially for agricultural purposes. 相似文献
49.
Walied M. Alarif Ahmed Abdel‐lateff Sultan S. AL‐lihaibi Seif‐Eldin N. Ayyad Farid A. Badria Abdulmohsin A. Alsofyani Zeinab S. Abou‐Elnaga 《洁净——土壤、空气、水》2013,41(11):1116-1121
Two new marine steryl hexadecanoates, 3β‐hexadecanoylcholest‐5‐en‐7‐one ( 1 ) and 3β‐hexadecanoylcholest‐5‐en‐7β‐ol ( 2 ), along with seven known compounds, cholest‐5‐en‐3β‐yl‐formate ( 3 ), thymidine ( 4 ), indole‐3‐carboxaldehyde ( 5 ), 3β‐hydroxycholest‐5‐en‐7‐one ( 6 ), cholesterol ( 7 ), 22‐dehydrocholestrol ( 8 ), and 24‐methylenecholesterol ( 9 ), were isolated from the anthozoan black coral, Antipathes dichotoma. The structures of all isolated compounds were determined by interpretation of their spectral data 1D (1H, 13C and DEPT) and 2D (COSY, HSQC and HMBC) NMR, UV, IR, and MS. Compounds 1 – 5 were evaluated for their anticancer activities, employing four cancer panels; HepG2, WI 38, VERO, and MCF‐7. All tested compounds, except 4 , showed moderate activities. Compound 4 exhibited significant anticancer activity against VERO and MCF‐7, with IC50 20.5 and 20.2 µg/mL, respectively. 相似文献
50.
Matthieu Dumont Said Taibi Jean‐Marie Fleureau Nabil Abou‐Bekr Abdelghani Saouab 《国际地质力学数值与分析法杂志》2011,35(12):1299-1317
A simple thermo‐hydro‐mechanical (THM) constitutive model for unsaturated soils is described. The effective stress concept is extended to unsaturated soils with the introduction of a capillary stress. This capillary stress is based on a microstructural model and calculated from attraction forces due to water menisci. The effect of desaturation and the thermal softening phenomenon are modelled with a minimal number of material parameters and based on existing models. THM process is qualitatively and quantitatively modelled by using experimental data and previous work to show the application of the model, including a drying path under mechanical stress with transition between saturated and unsaturated states, a heating path under constant suction and a deviatoric path with imposed suction and temperature. The results show that the present model can simulate the THM behaviour in unsaturated soils in a satisfactory way. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献