International viewpoint and news     

M. Al Ibrahim  D. Govoni 《Environmental Geology》2008,55(2):465-466

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Paleomagnetism of Carboniferous sediments from the West Sudetes (SW Poland)     

Kądziałko-Hofmokl  Magdalena  El-Hemaly  Ibrahim Aly 《Geologie en Mijnbouw》1997,76(1-2):97-104

The studied Carboniferous flysch and molasse sediments from the Intra-Sudetic Basin correspond to the period from Middle Visean to Early Autunian. Main magnetic minerals carrying the natural remanent magnetization (NRM) are goethite, magnetite, maghemite and hematite, all usually secondarily formed and/or remagnetized due to several tectonometamorphic events. In most samples several NRM components were isolated. One of them is usually a Jurassic-Triassic overprint. Some others define the Westphalian-Early Permian segment of the declination and inclination trajectory for the Sudetes calculated according to the reference apparent polar wander path for the Baltica plate. The Sudetic path is slightly shifted to the east compared to the reference path, suggesting the possibility of independent movements of the Sudetes during this time. The majority of isolated NRM components are secondary and related to the Sudetic orogenic phase and later tectonometamorphic activity.  相似文献   

Effect of hot dry summer tropical climate on forage intake and milk yield in Holstein–Friesian and indigenous zebu cows in Sudan     

Muna Mahjoub M Ahmed  Adam Ibrahim El Amin 《Journal of Arid Environments》1997,35(4):737-746

The effects of dry summer ambient temperature on some physiological and productive responses were studied in an exotic European breed (Holstein–Friesian) and a local zebu breed (Butana ecotype) of cattle in Sudan. Rectal temperature and respiration rate were positively correlated, and dry matter intake and milk yield were negatively correlated with variation in ambient temperature. However, significant adverse effects on high ambient temperature were only observed in the exotic breed.  相似文献   

The Southern Sudanese migration to Khartoum and the resultant conflicts     

F. N. Ibrahim Prof. Dr. 《GeoJournal》1991,25(1):13-18

Today, more than one third of the population of Khartoum are southerners who migrated to the capital mainly in the last eight years because of the civil war. Their conditions are very bad. They are starving in the town, for most of them are unemployed and have no means of living. Their housing conditions in the shanty towns are deplorable. The development of squatter settlements and the struggle for the demarcation of quarters are delineated in this paper. In Khartoum the southerners develop a strong sense of solidarity and develop a growing supra-southern-Sudanese identity replacing the former ethnic and local identities.  相似文献   

Groundwater Discharge as a Source of Dissolved Carbon and Greenhouse Gases in a Subtropical Estuary   总被引：1，自引：0，他引：1  

Mahmood Sadat-Noori  Damien T. Maher  Isaac R. Santos 《Estuaries and Coasts》2016,39(3):639-656

Groundwater may be highly enriched in dissolved carbon species, but its role as a source of carbon to coastal waters is still poorly constrained. Exports of deep and shallow groundwater-derived dissolved carbon species from a small subtropical estuary (Korogoro Creek, Australia, latitude ?31.0478°, longitude 153.0649°) were quantified using a radium isotope mass balance model (²³³Ra and ²²⁴Ra, natural groundwater tracers) under two hydrological conditions. In addition, air-water exchange of carbon dioxide and methane in the estuary was estimated. The highest carbon inputs to the estuary were from deep fresh groundwater in the wet season. Most of the dissolved carbon delivered by groundwater and exported from the estuary to the coastal ocean was in the form of dissolved inorganic carbon (DIC; 687 mmol m^?2 estuary day^?1; 20 mmol m^?2 catchment day^?1, respectively), with a large export of alkalinity (23 mmol m^?2 catchment day^?1). Average water to air flux of CO₂ (869 mmol m^?2 day^?1) and CH₄ (26 mmol m^?2 day^?1) were 5- and 43-fold higher, respectively, than the average global evasion in estuaries due to the large input of CO₂- and CH₄-enriched groundwater. The groundwater discharge contribution to carbon exports from the estuary for DIC, dissolved organic carbon (DOC), alkalinity, CO₂, and CH₄ was 22, 41, 3, 75, and 100 %, respectively. The results show that CO₂ and CH₄ evasion rates from small subtropical estuaries surrounded by wetlands can be extremely high and that groundwater discharge had a major role in carbon export and evasion from the estuary and therefore should be accounted for in coastal carbon budgets.  相似文献   

Tracking the hydrodynamic behavior of fine sediment using particle image velocimetry     

Masoumeh MoayeriKashani  S. H. Lai  S. Ibrahim  N. M. N. Sulaiman  F. Y. Teo 《Environmental Earth Sciences》2016,75(8):676

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Middle Miocene ostracods from Wadi Sudr,westcentral Sinai,Egypt: systematic,biostratigraphy and palaeobiogeographic affinity with the Mediterranean realm     

Ibrahim M. Ied  Abdelmoneim S. A. Ismail 《Arabian Journal of Geosciences》2016,9(5):406

The investigation of the exposed middle Miocene strata from Wadi Sudr yielded well-preserved ostracod carapaces. Detailed taxonomic and paleontological studies led to the recognition of 36 ostracod species belonging to 25 genera, 4 species of them were considered new which fully described. Three assemblage biozones were recorded as follows: Actinocythereis spinosa–Actinocythereis hystrix zone, Chrysocythere cataphracta muricata-Cytheretta africana zone, and Disopontocypris schweijeri-Bythocypris tripolensis zone. The recorded biozones were calibrated with the previously studied middle Miocene planktonic foraminiferal biozones on the same samples and also correlated with the Miocene ostracod biozones from the neighboring countries. Our ostracod assemblages present in the lower and upper parts of the studied section (section II) indicated an inner neritic marine environment of moderate energy of currents and rapid sedimentation, while the assemblages in the middle part showed more deeper (outer neritic) environments with low energy of currents and low rate of sedimentation. The palaeobiogeographic distribution of the studied ostracods showed high affinity with the ostracod assemblages of the southern Mediterranean and moderate to low affinities with that of the northern and eastern Mediterranean respectively. The highly ornamented ostracod species with structures on the carapace were recorded from both Northern and Southern Mediterranean, while the smooth ones were found in the Southern Mediterranean only. The highly ornamented species are more widely distributed in both Southern and Northern Mediterranean than the smooth species. This may indicate that the ornamented species are more able to migrate than the smooth ones.  相似文献   

Biodegradation of Remazol Black B in sequential microaerophilic–aerobic operations by NAR-2 bacterial consortium     

S. Nazanin Kardi  Noor Aini Abdul Rashid  Norahim Ibrahim  Azura Ahmad 《Environmental Earth Sciences》2016,75(16):1172

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Multivariate statistical analysis for identifying water quality and hydrogeochemical evolution of shallow groundwater in Quaternary deposits in the Lower Kelantan River Basin,Malaysian Peninsula     

Nur Hayati Hussin  Ismail Yusoff  Wan Zakaria Wan Muhd Tahir  Ibrahim Mohamed  Adriana Irawati Nur Ibrahim  Adzhar Rambli 《Environmental Earth Sciences》2016,75(14):1081

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Efficiency of reduced-order, time-dependent adjoint data assimilation approaches     

Ibrahim Hoteit  Armin Köhl 《Journal of Oceanography》2006,62(4):539-550

Applications of adjoint data assimilation, which is designed to bring an ocean circulation model into consistency with ocean observations, are computationally demanding. To improve the convergence rate of an optimization, reduced-order optimization methods that reduce the size of the control vector by projecting it onto a limited number of basis functions were suggested. In this paper, we show that such order reduction can indeed speed up the initial convergence rate of an assimilation effort in the eastern subtropical North Atlantic using in situ and satellite data as constraints. However, an improved performance of the optimization was only obtained with a hybrid approach where the optimization is started in a reduced subspace but is continued subsequently using the full control space. In such an experiment about 50% of the computational cost can be saved as compared to the optimization in the full control space. Although several order-reduction approaches seem feasible, the best result was obtained by projecting the control vector onto Empirical Orthogonal Functions (EOFs) computed from a set of adjusted control vectors estimated previously from an optimization using the same model configuration.  相似文献