Geochemistry and origin of the Cretaceous sedimentary kaolin deposits,Red Sea,Egypt     

Hassan M. Baioumy 《Chemie der Erde / Geochemistry》2014

This work reports, for the first time, the mineralogical and geochemical characteristics of the Cretaceous sedimentary kaolin deposits in the Red Sea area, Egypt and sheds the light on their source. Mineralogical and geochemical analyses of both bulk deposits and the sand and clay fractions of these deposits indicated that they are composed of kaolinite (average of 75 wt.%) and quartz (average of 22 wt.%). Traces of anatase (average of 1 wt.%) were identified in all kaolin samples, while traces of halite (average of 2 wt.%) and hematite (average of 1 wt.%) were reported in the majority of the analyzed samples. The clay fractions show relatively high contents of TiO₂ (average of 2.1%), Ni (average of 103 ppm), Nb (average of 98 ppm), Y (average of 67 ppm), and Zr (average of 630 ppm). Sum of the rare earth elements (ΣREE) in the clay fractions varies between 193 and 352 ppm. Chondrite-normalized REE patterns show enrichment of the light REE relative to the heavy REE ((La/Yb)_N = 9) and negative Eu anomaly (Eu*/Eu = 0.67).  相似文献   

Uptake of Indosol Dark-blue GL dye from aqueous solution by water hyacinth roots powder: adsorption and desorption study     

Md. M. R. Khan  M. Z. B. Mukhlish  M. S. I. Mazumder  K. Ferdous  D. M. R. Prasad  Z. Hassan 《International Journal of Environmental Science and Technology》2014,11(4):1027-1034

Adsorption characteristics of water hyacinth roots powder for the removal of Indosol Dark-blue GL dye were investigated in batch mode. Operating variables, such as initial solution pH, presence of detergent, adsorbent dosage, initial concentration and contact time, were studied. The results showed that the adsorption of dye increased with increasing the initial concentration and contact time. The adsorption is highly pH dependent and adsorption capacity increased with decrease in pH. Kinetic study revealed that the uptake of Indosol Dark-blue GL was very rapid within the first 15 min and equilibrium time was independent of initial concentration. Batch equilibrium experiments were carried out at different pH and found that equilibrium data fitted well to Langmuir isotherm model. The maximum sorption capacity of the adsorbent was found as 86 mg g^?1 at pH 3 which reduced to 64 mg g^?1 at pH 5. The presence of detergent reduced the sorption capacity of the adsorbent significantly. Using equilibrium and kinetic data, the forward and backward rate constants were determined from the unified approach model. Desorption study revealed that the dye can be recovered by swing the pH from low to high.  相似文献   

Mapping hotspots of underground water quality based on the variation of chemical concentration in Amman,Zarqa and Balqa regions,Jordan     

Khaled A. Alqadi  Lalit Kumar  Hassan M. Khormi 《Environmental Earth Sciences》2014,71(5):2309-2317

This study uses geographic information systems to map the hotspots level changes in underground water quality based on pH, nitrate and conductivity in Amman, Zarqa and Balqa regions, Jordan using data from 57 wells. The chemical concentration for each parameter was obtained from the Water Authority of Jordan. The data were tested according to ISO/IEC 17025 standards by the Jordan Inorganic Laboratory of the Laboratories and Quality Department of Water Authority for 2004 and 2010 and were processed using Getis-Ord Gi statistics. The study indicated that there are periodic fluctuations for the values of selected chemical elements of groundwater that are localized, creating contamination hotspots within the study regions. The pH, nitrate and conductivity all indicated specific hotspots of higher than average values in 2004 and 2010 in the Zarqa region. The evidence indicates that there are two major localized areas of high value for all parameters centered in the western Zarqa region, an area dominated by urban infrastructure and irrigated lands. These findings have implications for the management of aquifer water quality through the identification of high-value hotspots. Because the aquifers in the regions are connected, understanding the hotspots with high pH, nitrate and conductivity values may enable improvements in the water quality across the aquifer systems in the regions.  相似文献   

Monitoring rangeland ground cover vegetation using multitemporal MODIS data     

Hassan Yeganeh  Seyed jamale Khajedein  Fazel Amiri  Abdul Rashid B. Mohamed Shariff 《Arabian Journal of Geosciences》2014,7(1):287-298

The aim of the present research is to monitor changes in herbage production during the grazing season in the Semirom and Brojen regions, Iran, using multitemporal Moderate Resolution Imaging Spectroradiometer (MODIS) data. At first, various preprocessing steps were applied to a topography map. The atmospheric and topographic corrections were applied using subtraction of the dark object method and the Lambert method. Image processing, including false-color composite, principal component analysis, and vegetation indices were employed to produce land use and pasture production maps. Vegetation sampling was carried out over a period of 4 months during June–September 2008, using a stratified random sampling method. Twenty random sampling points were selected, and herbage production was estimated and verified with the double-checking method. Four MODIS data sets were used in this study. The models for image processing and integrating ground data with satellite images were processed, and the resulting images were categorized into seven classes. Finally, the land covers were verified for accuracy. A postclassification analysis was carried out to verify the seven class change detections. The results confirmed that Normalized Difference Vegetation Index (NDVI) and Soil-Adjusted Vegetation Index (SAVI) maps had a close relationship with the field data. The indices produced with shortwave infrared bands had a close relationship with field data where the ground cover and yields were high. The R ² value observed was 0.85. The changes in the pasture vegetation were high during the growing season in more than 90 % of the pastures. During the growing season, most changes in the pastures belonged to class 5 and 2 in the NDVI and SAVI index maps, respectively.  相似文献   

Drought risk assessment using remote sensing and GIS techniques   总被引：1，自引：0，他引：1  

Abdel-Aziz Belal  Hassan R. El-Ramady  Elsayed S. Mohamed  Ahmed M. Saleh 《Arabian Journal of Geosciences》2014,7(1):35-53

Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors.  相似文献   

Simulation of the lately injected dykes in an Iranian porphyry copper deposit using the plurigaussian model     

Hassan Talebi  Omid Asghari  Xavier Emery 《Arabian Journal of Geosciences》2014,7(7):2771-2780

Ore deposits are usually composed of rock units or facies with different grade distributions and complex spatial structures. Being able to simulate the spatial layout of these facies are essential to have a comprehensive mining plan and an accurate resources and reserves evaluation. Modelers are faced with a set of challenges when creating the facies model such as: reproducing the facies proportions and spatial continuity as well as the topological contacts between facies, capturing post depositional overprinting, and honoring the data obtained from drill holes. Plurigaussian simulation (PGS) is a geostatistical approach that allows covering these challenges. This study addresses the application of PGS to Sungun porphyry copper deposit (Iran), in order to simulate the layout of three facies: mineralized porphyry and skarn and non-mineralized dykes. The aim of this study is to construct numerical models in which the dyke structures reflect the evolution observed in the geology.  相似文献   

A Neuro-Fuzzy modeling for prediction of solar cycles 24 and 25     

Abdel-Fattah Attia  Hamed A. Ismail  Hassan M. Basurah 《Astrophysics and Space Science》2013,344(1):5-11

The paper presents a Neuro-Fuzzy model to predict the features of the forthcoming sunspot cycles 24 and 25. The sunspot time series were analyzed with the proposed model. It is optimized based on Backpropagation scheme and applied to the yearly smoothed sunspot numbers. The appropriate number of network inputs for the sunspots data series is obtained based on sequential forward search for the Neuro-Fuzzy model. According to the model prediction the maximum amplitudes of the cycles 24 and 25 will occur in the year 2013 and year 2022 with peaks of 101±8 and 90.7±8, respectively. The correlation and error analysis are discussed to ensure the performance of the proposed Neuro-Fuzzy approach as a predictor for sunspot time series. The correlation coefficient between Neuro-Fuzzy model forecasted sunspot number values with the actual ones is 0.96.  相似文献   

Partitioning of Se, As, Sb, Te and Bi between monosulfide solid solution and sulfide melt - Application to magmatic sulfide deposits   总被引：1，自引：0，他引：1  

Hassan M. Helmy  Chris Ballhaus  Raúl O.C. Fonseca 《Geochimica et cosmochimica acta》2010,74(21):6174-6179

The chalcogenes (S, Se, Te), semimetals (As, Sb) and the metal Bi are important ligands for noble metals and form a wide range of compositionally diverse minerals with the platinum-group elements (PGE). With the exception of S, few experimental data exist to quantify the behavior of these elements in magmatic sulfide systems. Here we report experimental partition coefficients for Se, Te, As, Sb, and Bi between monosulfide solid solution (mss) and sulfide melt, determined at 950 °C at a range of sulfur fugacities (fS2) bracketed by the Fe-FeS (metal-troilite) and the Fe_1−×S-S_x (mss-sulfur) equilibria. Selenium is shown to partition in mss-saturated sulfide melt as an anion replacing S²⁻. Arsenic changes its oxidation state with fS₂ from predominantly anionic speciation at low fS₂, to cationic speciation at high fS₂. The elements Sb, Te, and Bi are so highly incompatible with mss that they can only be present in sulfide melt as cations and/or as neutral metallic species. The partition coefficients derived fall with increasing atomic radius of the element. They also reflect the positions of the respective elements in the Periodic Table: within a group (e.g., As, Sb, Bi) the partition coefficients fall with increasing atomic radius, and within a period the elements of the 15th group are more incompatible with mss than the neighboring elements of the 16th group.  相似文献   

Stratigraphy,deposition, and structural framework of the cretaceous (review) and 3D geological model of the lower cretaceous reservoirs,Masila oil field,Yemen     

Hassan S. Naji  Mohammad H. Hakimi  Mohammed Khalil  Farooq A. Sharief 《Arabian Journal of Geosciences》2010,3(3):221-248

The Masila area is located in the Hadhramaut region in east central Yemen. Oil was first discovered in the area in late 1990 with commerciality being declared in late 1991. Oil production began in July 1993. By the end of December 1999, the daily production rate was set at 210,000 stock tank barrels/day (STB/D) of very low gas–oil ratio (GOR) oil under partial to full water drive. About 90% of the reserves are found in the Lower Qishn Clastics Member of the Qishn Formation. This paper focuses on the detailed 3D geological modeling of the Lower Cretaceous Sequence conducted through an integrated study. There are three critical areas in the process of modeling reservoirs that involve geological and geophysical modeling, reservoir characterization, and reservoir flow modeling. This paper presents methodologies found useful during the modeling of these reservoirs including field case histories for the Lower Cretaceous reservoir in the Masila oilfield.  相似文献   

A method for matching response spectra of endurance time excitations via the Fourier transform     

Mashayekhi  Mohammadreza  Estekanchi  Homayoon E.  Vafai  Hassan 《地震工程与工程振动(英文版)》2020,19(3):637-648

The endurance time(ET) method is a dynamic analysis in which structures are subjected to intensifying excitations, also known as ET excitation functions(ETEF). The ET method is a tool for structural response prediction. The main advantage of the ET method over conventional approaches is its much lower demand for computational efforts. The concept of acceleration spectra is used in generating existing ETEFs. It is expected that ETEF acceleration spectra increase consistently with time and remain proportional to a target spectrum. Nonlinear unconstrained optimization is commonly used to generate ETEFs. Generating new ETEFs is a complicated time-consuming mathematical problem. If the target acceleration spectrum changes, new ETEFs must be generated. This study intends to modify existing ETEFs to be compatible with a desired acceleration spectrum. This process, called spectral matching, obviates the need for using the complicated generating procedure in simulating new ETEFs. ETEFs spectral matching is introduced in this paper for the first time. A Fourier-based method for ETEFs spectral matching is proposed. This algorithm is then applied in a case study. Results are presented to prove the efficiency of the algorithm.  相似文献