Hydrobiological variables as a regulatory factor on the abundance of heterotrophic flagellates in an urban pond     

Begum  Moni  Jewel  Md. Abu Sayed  Haque  Md. Ayenuddin  Khatun  Mst. Samsad 《中国海洋湖沼学报》2019,37(3):1030-1036

The seasonal abundance of flagellates has been monitored over a period of 1 year from December2013 to November 2014(divided into 4 conjugative seasons namely winter, spring, summer, and autumn) in an experimental pond located in Rajshahi City Corporation area, Bangladesh. To our knowledge, this study is the first to shed light on the occurrence and possible interrelationships among heterotrophic flagellates(HF),bacteria and zooplankton in Bangladesh and the result obtained by this study will be beneficial for similar water ecosystem all over the world. Standard methods were used to determine the prescribed hydrological parameters and zooplankton cell density. Maximum HF abundance(14 346.00 cells/mL) was found in the spring and the minimum(5 215.00 cells/mL) occurred in the summer. Inverse to HF, significantly(P0.05)higher zooplankton abundance was found during the winter(782.00±47.62 cells/mL) and the lowest value was found in the autumn(448.00±39.15 cells/mL). Whereas similar to the HF, total bacterial abundance was significantly higher during the spring((2.25±1.05)×10~5 cells/mL) and lower in the summer((0.79±0.06)×105 cells/mL). Multivariate analyses(ANOSIM and MDS) have shown significant seasonal differences for cell numbers where MDS ordination plot and cluster analysis based on similarity in the genera abundance of HF revealed overlapping condition between winter and spring. Canonical correspondence analysis(CCA) also showed a distinct separation among the genera based on the prevailing hydrological situation and indicated that temperature, pH, BOD_5, and NO_3~- were the most important environmental variables in determining the observed variation in HF community structure. Among the biological factors, zooplankton showed negative but total bacteria were positively correlated with HF abundance.  相似文献   

Biotic response to the latest Cenomanian drowning and OAE2: A case study from the Eastern Desert of Egypt     

Emad Nagm  Sreepat Jain  Kamel Mahfouz  Ahmed El-Sabbagh  Aziz Abu Shama 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(1):70-92

The changes in macrofauna and microfauna, before, during and after the latest Cenomanian global Oceanic Anoxic Event (OAE2), from the Eastern Desert of Egypt are documented, along with an inferred paleoenvironment. The age of the studied OAE2 interval is constrained by the last occurrence of the marker calcareous nannofossils species Axopodorhabdus albianus along with the previously identified positive δ¹³C excursion from the coeval ammonite Vascoceras cauvini Zone (= Neocardioceras juddii Zone), enabling correlation with the peak ‘b’ of the OAE2. Based on the studied microfaunal assemblages, a warm shallow restricted lagoonal environment with mesotrophic conditions and strong seasonality is inferred. The presence of a rare ammonite (and ostracods) attest to the intermittent introduction of marine waters within this inner ramp setting. In terms of sequence stratigraphy, two 3rd order depositional sequences are recorded. The top surface of the first depositional sequence, at the sequence boundary, SB Ce 5 (the start of the OAE2), is marked by an abrupt faunal change with reduced abundances of the macrofaunal elements. This is in tune with other Egyptian records of relatively smaller loss (10 %) at the Cenomanian-Turonian boundary, as compared to much higher numbers (53–79% of species), globally. This faunal (biotic bottleneck) and lithological change (from siliciclastic-dominated deposits to a largely carbonate-dominated one) at the SB Ce 5 is attributed as a response to the latest Cenomanian drowning (the highest sea-level during the Phanerozoic), that also resulted in the formation of carbonate platform.  相似文献   

Evaluation of the ASL and Hawara formations using seismic- and log-derived properties, October Oil Field, Gulf of Suez, Egypt     

Aref Lashin  Nassir Al-Arifi  Nassir Abu Ashour 《Arabian Journal of Geosciences》2011,4(3-4):365-383

October Field is one of the most prolific offshore oil fields in the Gulf of Suez of Egypt. It consists of a number of marine platforms and produces oil from different reservoirs of different geological ages from the Lower Cretaceous to the Miocene. The aim of this study was to enhance a seismic-log evaluational procedure to evaluate the Miocene-aged Asl and Hawara Formations which encounter the main hydrocarbon and source rock potentials in the area North of October Oil Field. The well logging data, the borehole seismic data, and the velocity surveys are all used in this study. A number of synthetic seismograms are constructed and interpreted together with the deduced seismic impedance and reflection coefficient data for many wells in the study area. In addition, a comprehensive velocity analysis is performed using the seismic times and the computed average and interval velocities. These seismic-derived parameters are primarily used in recognizing and locating precisely the marl and sand sections of Asl Formation which show low to middle amplitudes. Furthermore, a quantitative well logging analysis is carried out over Asl and Hawara Formations to shed light over their hydrocarbon potentiality. Good oil saturation is exhibited by the Asl sand section which reaches to more than 90% in the southern parts of the study area. The petrophysical characters of this sand are very good in terms of good effective porosity (9% to13%), low shale volume (V _sh?<?5%), and high oil saturation (S _h?>?85%). The sections of the Asl marl and the Hawara shale on the other hand are considered completely wet. An integrated model making use of the seismic- and log-derived properties is applied over the two studied formations for better understanding the reservoir of interest. Many relations are constructed between velocity, seismic impedance, and the rock pore spaces on one hand and between the velocity, lithology, and fluid content on the other hand. This study revealed that the sand section attains very good oil-bearing potentiality in the study area and proved that the application of an integrated model of the log- and seismic-derived properties led to an enhanced evaluation of the Asl and Hawara Formations, good discrimination between their lithological components besides precise differentiation from the overlying Middle to Late Miocene sections.  相似文献   

Seasonal Changes in Mayfly Communities and Abundance in Relation to Water Physicochemistry in Two Rivers at Different Elevations in Northern Peninsular Malaysia     

Suhaila Abdul Hamid  Mohd Ravi Che Salmah  Hamady Dieng  Abu Hassan Ahmad  Tomomitsu Satho  Fumio Miake 《湿地科学》2011,9(3):240-250

A field study was performed at rivers in Gunung Jerai forest reserve(Kedah,Malaysia) to assess seasonal changes in mayfly community structure and abundance in relation to altitude and water physicochemistry.Rivers at lower(Batu Hampar River) and higher(Teroi River) elevations were visited through dry and wet seasons in September 2007 to August 2008.Monthly visits were made to 20 sites on each river,and water and aquatic insects were sampled using D-pond aquatic nets.Water was warmer,more acid,and more turbid in Teroi River during wet season.Ammonia was the only nutrient exhibiting significant seasonal variations(greater during wet season).Chemical oxygen demand content was higher in Teroi River where biochemical oxygen demand content was low during wet season.Species richness was higher in Batu Hampar River,but displayed seasonal variations only in Teroi River.Among the eight families encountered,Baetidae was the commonest.Baetid abundance was usually high during wet season,and those belonging to the dominant genus(Baetis) were more abundant in Teroi River.Heptageniidae was the second commonest family;its predominant genus,Thalerospyrus was more abundant in Teroi River during dry season.Caenidae,Leptophlebiidae and Oligoneuriidae were only found in Batu Hampar River where their abundances peaked during dry season,i.e.,Habrophlebiodes sp.and Isonychia sp.Ephemerellidae and Teloganodidae occurred only in Teroi River,with the first found only during dry season.Mayflies were recorded under very distinct physicochemical conditions,illustrating their potential usefulness for assessing water quality.Caenids,leptophlebids,oligoneurids ephemerellids and teloganodids seem to be particularly sensitive to temperature,acidity,turbidity,chemical oxygen demand and biochemical oxygen demand,parameters that varied with river altitude.  相似文献   

Anthropogenic particle dispersions in topsoils of the Middle Nile Delta: a preliminary study on the contamination around industrial and commercial areas in Egypt     

Atef M. Abu Khatita  Helga de Wall  Roman Koch 《Environmental Earth Sciences》2016,75(3):264

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Correction to: Speaking of the devil: a systematic literature review on community preparedness for earthquakes     

Shaffril  Hayrol Azril Mohamed  Samah  Asnarulkhadi Abu  Kamarudin  Syafila 《Natural Hazards》2021,108(3):2421-2421

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Hydrothermal alteration and evolution of Zr-Th-U-REE mineralization in the microgranite of Wadi Ras Abda,North Eastern Desert,Egypt     

Amr Abdel Aty Abdel Hamid  Hassan Ismail El Sundoly  Ahmed Ali Abu Steet 《Arabian Journal of Geosciences》2018,11(11):273

Ras Abda plutonic suite, North Eastern Desert of Egypt, consists predominantly of Neoproterozoic calc-alkaline older granites. Minor exposures of pink microgranite are occurring along Wadi Ras Abda within the older granites. Previous studies on this area demonstrated that the microgranite is altered in some parts and contains anomalous concentrations of rare metal elements (Zr, Th, and U). These altered and mineralized zones are re-assessed using field observations, chemical analysis, and by the application of various transmitted light and electron microscopic techniques. The rare metals exist as mineral segregation grew freely into open cavities of the microgranite and concordant with the NNE strike-slip fault movement. The mineralized zones contain an assemblage of secondary magnetite, zircon, uranothorite, columbite-(Mn), fergusonite-(Y), and allanite-(Ce). The extreme abundance of zircon in the mineralized zone, along with other evidence, indicates a hydrothermal origin of this zircon together with associated rare metals. The geochemical investigation and mass balance calculations revealed extreme enrichment of Zr, Th, U, Y, Nb, Ta, and REE. Post-magmatic hydrothermal alterations resulted in such pronounced chemical and mineralogical heterogeneity. The hydrothermal fluids are thought to be oxidizing, alkaline and of medium temperature (>?250 °C). The average contents of the elements Zr (1606 ppm), Th (1639 ppm), U (306 ppm), Nb (955 ppm), and REE (1710 ppm) in the mineralized microgranite reach sub-economic levels and could be a potential source of these elements.  相似文献   

The present-day active deformation in the central and northern parts of the Gulf of Suez area,Egypt, from earthquake focal mechanism data     

I. Abu El-Nader  H. M. Hussein 《Natural Hazards》2018,92(3):1355-1369

The average seismic strain rate is estimated for the seismotectonic zone of the northern/central parts of the Gulf of Suez. The principal strain rate tensor and velocity tensor were derived from a combination of earthquake focal mechanisms data and seismic moment of small-sized earthquakes covering a time span of 13 years (1992–2004). A total of 17 focal mechanism solutions have been used in the calculation of the moment tensor summation. The local magnitudes (MLs) of these events range from 2.8 to 4.7. The analysis indicates that the dominant mode of deformation in the central and northern parts of the Gulf of Suez is extension at a rate of 0.008 mm/year in N28°E direction and a small crustal thinning of 0.0034 mm/year. This low level of strain means that this zone experienced a little seismic deformation. There is also a right lateral shear motion along the ESE–WNW direction. This strain pattern is consistent with the predominant NW–SE normal faulting and ESE–WNW dextral transtensive faults in this zone. Comparing the results obtained from both stress and strain tensors, we find that the orientations of the principal axes of both tensors have the same direction with a small difference between them. Both tensors show a predominantly extensional domain. The nearly good correspondence between principal stress and strain orientations in the area suggests that the tectonic strength is relatively uniform for this crustal volume.  相似文献   

Computerised development control and approval system for City Hall of Kuala Lumpur     

AhrisYaakup YazidAbuBakar MohdNuruddin AbdulKadir SusilawatiSulaiman 《地球空间信息科学学报》2004,7(1):39-49

This paper will discuss the computerised development control and approval system being developed for the Planning and Development Control Department, City Hall of Kuala Lumpur, with stress on the GIS architecture developed within the system. The prospects and challenges towards implementation of the system are also discussed.  相似文献   

Rock slope stability and design in Arafat–Muzdalifa area,Saudi Arabia     

Ali M. A. Abd-Allah  E. K. El-Sawy  El-Sayed Sedek Abu Seif  Abdelhamid El-Fakharani  Mohammed Amin M. Sharaf 《Arabian Journal of Geosciences》2014,7(10):4029-4042

The present contribution is a complete study extending before, during, and after the excavation of the mountain side that lying north of road 7. It includes slope stability analysis, rock cut design, and rockfall modeling for natural slope and rock cut face. Neoproterozoic granodiorite and biotite granite forming the slope body have medium to very high strengths. Mineral compositions and textures of these intact rocks control the strength values. These rocks are intensively dissected by fractures that are filled with montmorillonite and chlorite. The high plasticity and slippery nature of these filling materials represent the main problem that may face a rock cut designer because they damage the mechanical properties of these fractures. The problem begins with the selection of the rock mass classification that deals with the fracture fillings and extends during the stability analysis and the suggestion of mitigation and supporting measures. The rock masses building the natural slope are suffered by plane, wedge, and toppling failures. Therefore, two rock cut designs are suggested to avoid the hazards related to these failures and considering the construction cost as well. Rockfall modeling for the natural slope and rock cut designs was done to assess the hazards related to these falling of the blocks. The kinetic energy of falling blocks is represented on the roadway by the coverage distance and block rebound amplitude. Slope height has a positive effect on the values of these distance and amplitude, whereas the steepness of berm height has a negative effect on them. Coverage distance is a function to the location of rockfall barrier and to the width of road ditch, while the amplitude controls the barrier height.  相似文献