Editorial     

Fouad N. Ibrahim 《GeoJournal》1987,14(1):9-10

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Orbital timing of the Indian,East Asian and African boreal monsoons and the concept of a ‘global monsoon’   总被引：1，自引：0，他引：1  

Thibaut Caley  Bruno Malaizé  Marie Revel  Emmanuelle Ducassou  Karine Wainer  Mohamed Ibrahim  Dina Shoeaib  Sébastien Migeon  Vincent Marieu 《Quaternary Science Reviews》2011,30(25-26):3705-3715

Our understanding of monsoon circulation timing’s at the orbital scale is currently a matter of debate. Here, we compare previous and recently published results of Indian, East Asian, West African and East African monsoon variability. We note different timings between the East African, West African, Indian and East-Asian monsoon systems for the most recent 45 ka, where the age models are constrained by AMS dating. On this basis, we construct different orbital forcing “reference curves” and apply them to the 200 ka time period for the different monsoon systems. Our results indicate that the ‘global monsoon’ concept at the orbital scale is a misnomer. We find real regional differences in the timing of the monsoon response to orbital forcing and differences in the weight of precession and obliquity in the monsoon records. This work highlights the necessity of studies aimed at understanding the underlying physics of these regional response patterns. This is crucial to a better understanding of monsoon dynamics and improved climate model simulations and comparisons with proxy data.  相似文献   

Petrophysical characteristics of Wakar Formation, Port Fouad marine field, north Nile Delta, Egypt     

Adel Mohamed  Elkhedr Ibrahim  Ahmed Sabry 《Arabian Journal of Geosciences》2013,6(5):1485-1497

Petrophysical characteristics of the late Miocene Wakar Formation of Port Fouad Marine Field have been evaluated through the analysis of well-logging records of nine exploratory and development wells, distributed in the northeastern offshore area of the Nile Delta. These records have been analyzed through utilizing the ELAN Plus petrophysics software in order to identify the lithological constituents and fluid saturation parameters. The gas potentialities of the studied formation have been evaluated through number of isoparameteric maps. The litho-saturation analysis indicates that the Wakar Formation in the studied wells is mainly gas-bearing with some water-bearing sand levels. The analytical formation evaluation reveals that the lithological facies consists mainly of sandstone, shale, and siltstone. The disseminated shale is mainly of dispersed type and some of laminated habitat. It also points to the dominance of the intergranular porosity. The isoparametric maps of the petrophysical parameters show that the level S1 of Wakar Formation is the main reservoir.  相似文献   

Monitoring the tectonic plate movements in Turkey based on the national continuous GNSS network     

Turgut Uzel  Kamil Eren  Engin Gulal  Ibrahim Tiryakioglu  Ahmet Anil Dindar  Haluk Yilmaz 《Arabian Journal of Geosciences》2013,6(9):3573-3580

In recent decades, the space geodesy has been applied to the areas such as transportation, infrastructure planning, navigation, etc. Among them, the precise positioning at the Global Navigation Satellite System (GNSS) stations yields better view in the understanding of the crustal deformation that requires global-scale measurements. There have been numerous studies examining the data process of continuous GNSS observations in the field of earth monitoring. More recently, GNSS stations established for continuously operating reference station networks have been beneficial resources in the tectonic plate-monitoring studies in lieu of campaign-type observations. However, this requires that the Continuously Operating Reference Station (CORS) should be established on stable structures acting like foundations and requires investigation of the long-term repeatability time series. This study aims to introduce recently established national CORS network, named CORS-TR, covering the entire Turkey and Northern Cyprus, and to explain the process of the long-term data obtained from the network on the characteristics of the tectonic plate movement within the area. The results of the CORS-TR data process present a great potential of using continuously operating reference stations not only in real-time kinematic applications of conventional geodesy studies but also in detecting and monitoring the crustal deformations of those that are crucial in earthquake-prone areas like Turkey. Since the findings are computed from the results of the all permanent stations of CORS-TR network, this study also examines the GNSS observation quality of the network for the given time interval. One of the major conclusions of the data process conducted in the study displays that the CORS-TR stations established on the carefully selected large and low-rise existing building had been more stable than the stations on the ground which have been subjected to soil settlement since the construction.  相似文献   

InterPreting effects of TOCinert organic content on source rock Potential using S2 vs. TOC graPh in Maamba Coalfield,southern Zambia     

Cryton Phiri  WANG Pujun  G Roland Nguimbi  Abdallah-Yousif Ibrahim Hassan 《世界地质(英文版)》2014,17(4):199-205

The authors Present the effects of the total organic carbon( TOCinert )during Pyrolysis and how it overall affects the estimates of the hydrocarbon index( HI)using the cross Plot S2 vs. TOC graPh. A to...  相似文献   

The use of dinoflagellate cysts to separate human-induced from natural variability in the trophic state of the Po River discharge plume over the last two centuries   总被引：1，自引：0，他引：1  

Zonneveld KA  Chen L  Elshanawany R  Fischer HW  Hoins M  Ibrahim MI  Pittauerova D  Versteegh GJ 《Marine pollution bulletin》2012,64(1):114-132

To obtain insight into the natural and/or human-induced changes in the trophic state of the distal portion of the Po River discharge plume over the last two centuries, high temporal resolution dinoflagellate cyst records were established at three sites. Cyst production rates appear to reflect the natural variability in the river's discharge, whereas cyst associations reflect the trophic state of the upper waters, which in turn can be related to agricultural development. The increased abundances of Lingulodinium machaerophorum and Stelladinium stellatum found as early as 1890 and 1920 correspond to the beginning of the industrial revolution in Italy and the first chemical production and dispersion of ammonia throughout Europe. After 1955, the increased abundances of these species and of Polykrikos schwartzii, Brigantedinium spp. and Pentapharsodinium dalei correspond to agriculturally induced alterations of the hypertrophic conditions. A slight improvement in water quality can be observed from 1987 onward.  相似文献   

Influences of Environmental and Operational Factors on Dark Fermentative Hydrogen Production: A Review     

Parviz Mohammadi  Shaliza Ibrahim  Mohamad Suffian Mohamad Annuar  Shahin Ghafari  Sabaratnam Vikineswary  Ali Akbar Zinatizadeh 《洁净——土壤、空气、水》2012,40(11):1297-1305

Hydrogen (H₂) is one of renewable energy sources known for its non‐polluting and environmentally friendly nature, as its end combustion product is water (H₂O). The biological production of H₂ is a less energy intensive alternative where processes can be operated at ambient temperature and pressure. Dark fermentation by bacterial biomass is one of multitude of approaches to produce hydrogen which is known as the cleanest renewable energy and is thus receiving increasing attention worldwide. The present study briefly reviews the biohydrogen production process with special attention on the effects of several environmental and operational factors towards the process. Factors such as organic loading rate, hydraulic retention time, temperature, and pH studied in published reports were compared and their influences are discussed in this work. This review highlights the variations in examined operating ranges for the factors as well as their reported optimum values. Divergent values observed for the environmental/operational factors merit further exploration in this field.  相似文献   

The link between trade openness and deforestation for environmental quality in Nigeria     

Ibrahim Kabiru Maji 《GeoJournal》2017,82(1):131-138

This paper examines the effect of trade openness on deforestation for environmental quality in Nigeria. Autoregressive Distributed Lag bounds testing approach to cointegration was used to achieved the long-run equilibrium relationship among the variables. Economic growth, energy consumption and population were used as control variable. The long-run result shows that the coefficients of trade openness and economic growth are significant and inversely related to deforestation. This suggests that trade openness and growth reduce deforestation and improves environmental quality. Conversely, the long-run coefficient of population is significant and positively related to deforestation, meaning that population increases deforestation and environmental degradation. However, the long-run result for energy consumption did not produce statistical significance. Furthermore, all the short-run results were consistent with their long-run result.  相似文献   

Environmental effects of tunnel excavation in soft and shallow ground with EPBM: the case of Istanbul   总被引：8，自引：4，他引：4  

Ibrahim Ocak 《Environmental Earth Sciences》2009,59(2):347-352

In metro tunnel excavations, it is important to control surface settlements observed before and after excavation, which may cause damage to surface structures. Otherwise, the metro tunnel cannot perform the task expected, and the advantages of the tunnel are lost. In this study, short-term surface settlements and their effect on buildings are examined in three zones for twin tunnels, which have been excavated between the Otogar and Kirazlı 1 stations of the Istanbul Metro line, and are 5.8 km in length. Geology in the study area is composed of fill, stiff clay, dense sand, very dense sand, and hard clay, respectively, starting from the surface. Tunnels are excavated by using two Earth Pressure Balance Tunnel Boring Machines (EPBMs) with a 6.5 m diameter as twin tubes with 14 m distance from center to center. The EPBM in the right tube is followed about 100 m behind the other tube. Segmental lining with 1.4 m of length is currently employed as final support. The results of this study indicate that, with EPBM excavation method in shallow depths and soft grounds, the damage done to the environment prolonged project costs up to 15.8% more. In addition, tunnel conditions prolonged the project schedule to 29.3%.  相似文献   

Groundwater balance in the Khor Arbaat basin, Red Sea State, eastern Sudan     

Abdalla E. M. Elsheikh  Khalid A. Elsayed Zeielabdein  Ibrahim A. A. Babikir 《Hydrogeology Journal》2009,17(8):2075-2082

The Khor Arbaat basin is the main source of potable water supply for the more than 750,000 inhabitants of Port Sudan, eastern Sudan. The variation in hydraulic conductivity and storage capacity is due to the heterogeneity of the sediments, which range from clay and silt to gravely sand and boulders. The water table rises during the summer and winter rainy seasons; it reaches its lowest level in the dry season. The storage capacity of the Khor Arbaat aquifer is estimated to be 21.75?×?10⁶ m³. The annual recharge through the infiltration of flood water is about 1.93?×?10⁶ m³. The groundwater recharge, calculated as underground inflow at the ‘upper gate’, is 1.33?×?10⁵ m³/year. The total annual groundwater recharge is 2.06?×?10⁶ m³. The annual discharge through underground outflow at the ‘lower gate’ (through which groundwater flows onto the coastal plain) is 3.29?×?10⁵ m³/year. Groundwater discharge due to pumping from Khor Arbaat basin is 4.38?×?10⁶ m³/year on average. The total annual groundwater discharge is about 4.7?×?10⁶ m³. A deficit of 2.6?×?10⁶ m³/year is calculated. Although the total annual discharge is twice the estimated annual recharge, additional groundwater flow from the fractured basement probably balances the annual groundwater budget since no decline is observed in the piezometric levels.  相似文献