The relationship among environmental variables,jellyfish and non‐gelatinous zooplankton: A case study in the north of the Gulf of Oman          下载免费PDF全文

Fatemeh Pourjomeh  Mohammad Reza Shokri  Hamid Rezai  Hassan Rajabi‐Maham  Elham Maghsoudlou 《Marine Ecology》2017,38(6)

Processes underlying the temporal and spatial variations observed in the distribution of jellyfish and non‐gelatinous zooplankton in the Gulf of Oman are not well understood. This information gap is clearly a major issue in controlling the harmful blooms of jellyfish and non‐gelatinous zooplankton. Samples of jellyfish and non‐gelatinous zooplankton were collected from six stations in Chabahar Bay and three stations in Pozm Bay within four seasons. At each station, environmental variables were also recorded from bottom and surface water. A total of 83 individuals of medusae representing four species of Scyphozoa (i.e., Cyanea nozakii, Chrysaora sp., Pelagia noctiluca, Catostylus tagi) and species of Hydrozoa (i.e., Diphyes sp., Rhacostoma sp., Aequorea spp.) were observed in the study area. A total of 70,727.25 individuals/m^?3 of non‐gelatinous zooplankton dominated by copepods and cladocerans were collected in nine stations within the four seasons. The results of a RELATE analysis yielded no significant association between species composition for jellyfish and non‐gelatinous zooplankton. Among environmental variables, water transparency, nitrite concentration, water depth and temperature were better associated with the total variation in jellyfish species composition than with that of non‐gelatinous zooplankton. Dissolved oxygen, pH, and phosphate concentration were significant environmental variables associated with the variation in the spatial and temporal distribution patterns of non‐gelatinous zooplankton assemblages. Although some jellyfish species (i.e., Rhacostoma sp., Pelagia noctiluca, Catostylus tagi) occur independently of non‐gelatinous zooplankton assemblages, other jellyfish (i.e., Chrysaora sp., Aequorea spp., Cyanea nozakii, Diphyes sp.) are strongly correlated with non‐gelatinous zooplankton assemblages.  相似文献   

Analysis of symbiotic Symbiodinium in scleractinian corals off Northwestern Kish Island,Persian Gulf          下载免费PDF全文

Amirhossein Gheitanchi Mashini  Mona Fard Yazdani  Pargol Ghavam Mostafavi  Mohammad Hassan Shahhosseiny 《Marine Ecology》2017,38(2)

The genus Symbiodinium plays an essential role in the resistance and survival of reef‐building corals during temperature anomalies. Coral colonies inhabiting the Persian Gulf (PG) experience extended periods of different stresses. Kish Island is located in the harsh environment of the Northern PG with previously reported bleaching episodes. Samples of six coral species from Northwestern Kish Island were analysed by internal transcribed spacer 2 of ribosomal DNA to identify in hospite Symbiodinium populations. The results showed that lineage D of Symbiodinium was the most prevalent clade among different coral colonies, while clade C was only detected in symbiosis with a single coral species. However, the detected Symbiodinium subclades belonged to two host generalists. The predominance of the stress tolerant Symbiodinium trenchii and subclade C3 could suggest an acclimatization strategy to cope with the hostile environment of the PG.  相似文献   

Application of the coral health chart to determine bleaching status of <Emphasis Type="Italic">Acropora downingi</Emphasis> in a subtropical coral reef     

Mahshid Oladi  Mohammad Reza Shokri  Hassan Rajabi-Maham 《Ocean Science Journal》2017,52(2):267-275

The ‘Coral Health Chart’ has become a popular tool for monitoring coral bleaching worldwide. The scleractinian coral Acropora downingi (Wallace 1999) is highly vulnerable to temperature anomalies in the Persian Gulf. Our study tested the reliability of Coral Health Chart scores for the assessment of bleaching-related changes in the mitotic index (MI) and density of zooxanthellae cells in A. downingi in Qeshm Island, the Persian Gulf. The results revealed that, at least under severe conditions, it can be used as an effective proxy for detecting changes in the density of normal, transparent, or degraded zooxanthellae and MI. However, its ability to discern changes in pigment concentration and total zooxanthellae density should be viewed with some caution in the Gulf region, probably because the high levels of environmental variability in this region result in inherent variations in the characteristics of zooxanthellae among “healthy” looking corals.  相似文献   

Assessing desertification by using soil indices   总被引：1，自引：0，他引：1  

Ali Khanamani  Hassan Fathizad  Haji Karimi  Saeed Shojaei 《Arabian Journal of Geosciences》2017,10(13):287

Desertification generally refers to land degradation in arid, semiarid, and dry semi-humid climatic zones. It involves five principal processes: vegetation degradation, water erosion, wind erosion, salinization and waterlogging, and soil crusting and compaction. The aim of this study is assessing desertification using soil criteria. For this purpose, nine indices including sodium absorption ratio (SAR), soil gypsum percentage, soil texture, the content of HCO₃ ^?, the percentage of the organic matter, electrical conductivity (EC), pH, the content of the soil sodium, and chloride were used. The soil samples were taken in the north of Zayandeh-Rood River in Isfahan province of Iran, using soil data randomly sampled in a depth of 0–20 cm. After assessing the normality of the samples using Kolmogorov-Smirnov test, indices were imported into GIS environment and interpolated with IDW and normal and discrete kriging methods for delineating soil characteristics maps based on MEDALUS model. In this model, the data were firstly changed from 100 to 200. Thus 100 and 200 are estimated as the best and worst quality, respectively. Then the final map of soil criteria has been created by geometric mean of its indicators. The results showed that the maximum area is related to the medium class of desertification and is equal to 44,746 ha. The areas of severe and very severe classes of desertification are equal to 30,949 and 351 ha, respectively. The results also revealed that the indices of the organic matter and soil gypsum percentage are the most influential indices which affect desertification phenomenon.  相似文献   

Mineralogy and physico-chemical properties of Wadi Badaa clays (Cairo-Suez district,Egypt): a prospective resource for the ceramics industry     

Sherif Kharbish  Hassan I. Farhat 《Arabian Journal of Geosciences》2017,10(7):174

The Wadi Badaa (WB) Upper Miocene clays, Cairo-Suez district, Egypt, represent materials for the ceramic production. The clay raw materials are composed mainly of smectite and kaolinite with minor quartz, calcite, and rare feldspar. The plasticity indices vary between 24 and 30%, suggesting that these clays are plastic raw materials. IR bands of the investigated clays were observed at 3695, 3619, 1032, 916, 794, 690, 534, 466, and 423 cm^?1 for kaolinite; at 3436, 1635, 916, and 466 cm^?1 for smectite; and at 1179, 1104, 794, 690, and 466 cm^?1 for quartz. The <2 μm particle sizes of samples are relatively abundant in clays (～33%), which is adequate for uses of the ceramic products because of containing fine particle sizes. The studied WB clays contain 7.95 and 12.35% moisture water and interlayer water, respectively, with a maximum drying shrinkage of 7.87% at room temperature; therefore, the WB clays could be used in the ceramic manufacture.  相似文献   

Identifying sources of soil classes variations with digital soil mapping approaches in the Shahrekord plain,Iran     

Zohreh Mosleh  Mohammad Hassan Salehi  Azam Jafari  Isa Esfandiarpoor Borujeni  Abdolmohammad Mehnatkesh 《Environmental Earth Sciences》2017,76(21):748

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Composition,radioactivity, and possible applications of kaolin deposits of Sinai,Egypt     

Ahmed El-Kammar  Hassan Taha Abu-Zied  Mohamed Galal  Dina Osman 《Arabian Journal of Geosciences》2017,10(21):463

This work discusses the composition, radioactivity, and possible utilization of the kaolin resources in Sinai which are hosted in thick sandstone sequences belonging to the Carboniferous (Wadi Khaboba) and Early Cretaceous (Wadi Iseila and Abansakar) ages. The characterization of kaolin was done by microscopic and SEM examination, supported by XRD and ICP-MS analyses. The studied kaolin resources consist of kaolinite, as the main constituent, associated with subsidiary dickite and halloysite, and minor contribution of smectite and illite. The most dominant non-clay mineral is quartz, besides minor gypsum, dolomite, and hematite. Ferrugination dominates, in most cases, at the upper boundaries of the kaolin lenses, suggesting possible supergene activity. The high Al₂O₃/SiO₂ ratio for the Cretaceous kaolin (0.54, in average) specifies its better grade relative to the Carboniferous kaolin (0.43, in average). The kaolin of the middle part of lens C in Wadi Iseila contains Si/Al molecular ratio of about unity, suggesting high-grade kaolin. The Carboniferous kaolin has enriched the radionuclides: U, Th, and Ra (at disequilibrium state due to leaching of eU relative to Ra) and the REE, relative to that of the Cretaceous age. The Carboniferous kaolin is characterized by a higher contribution of HREE (zircon signature), whereas LREE seems to be more influential for the Early Cretaceous kaolin (monazite signature). In spite of the very high CIA index (93 to 99), none of the analyzed kaolin deposits displays Ce abnormality. The high radioactivity of some Carboniferous kaolin can be a serious impediment for its utilization or its exportation. The kaolin of Sinai does not satisfy the international standards for paperwork industries and refractory manufacturing, but beneficiation may overcome this challenge. However, some lenses have high-grade kaolin with a low percentage of oxides of iron, magnesium, calcium, sodium, and potassium and a low radioactivity, hence nominated for the local refractory industry. The high-grade kaolin of Sinai fulfills the standards required for ceramics manufacturing in the global market. Grade 3 kaolin (< 30%, Al₂O₃) can be used in the manufacturing of white Portland cement and red glaze manufacturing on both local and global markets.  相似文献   

Development of functionalized carrageenan,chitosan and alginate as polymeric chelating ligands for water softening     

K. A. Ali  M. E. Hassan  M. M. M. Elnashar 《International Journal of Environmental Science and Technology》2017,14(9):2009-2014

Chitosan, carrageenan and alginate are among the most abundant biopolymers in nature. They were prepared in uniform beads shape with a diameter of 2 mm ± 10%, using the encapsulator for removal of calcium, magnesium and iron cations from hard water. Solutions of 100–500 mg/L were prepared from each cation, and the detection of cations was carried out using atomic absorption spectrometer. Carrageenan and chitosan were able to chelate the three cations without further modification. However, alginate beads succeeded to chelate iron and magnesium and failed to chelate any calcium ions; in contrast, it increased the initial calcium concentration! That could be due to the pre-cross-linking of alginate beads using calcium chloride solution, which may be leaked back to the solution. However, grafting the alginate beads with polyethyleneimine and bromoacetic acid rectified this problem and the new functional group, –COOH, has been proved using the FT-IR. Optimization of the results in terms of beads weight (0.25–3.0 g) and cations concentrations (100–500 mg/L) has shown that most biopolymeric beads can chelate 85–100% of the cations in concentrations up to 500 mg/L. According to our finding, we came up with the recommendation to use chitosan for chelation of calcium and iron as it showed 100% chelation efficiency of both cations, whereas carrageenan is highly recommended for chelation of iron and magnesium, as it showed 100 and 98% chelation efficiency, respectively. Further work can be done on the reusability of the beads and scale up for the industrial use.  相似文献   

Assessment of proposed approaches for bathymetry calculations using multispectral satellite images in shallow coastal/lake areas: a comparison of five models     

Hassan Mohamed  AbdelazimNegm  Mahmoud Salah  Kazuo Nadaoka  Mohamed Zahran 《Arabian Journal of Geosciences》2017,10(2):42

Bathymetric information for shallow coastal/lake areas is essential for hydrological engineering applications such as sedimentary processes and coastal studies. Remotely sensed imagery is considered a time-effective, low-cost, and wide-coverage solution for bathymetric measurements. This study assesses the performance of three proposed empirical models for bathymetry calculations in three different areas: Alexandria port, Egypt, as an example of a low-turbidity deep water area with silt-sand bottom cover and a depth range of 10.5 m; the Lake Nubia entrance zone, Sudan, which is a highly turbid, unstable, clay bottom area with water depths to 6 m; and Shiraho, Ishigaki Island, Japan, a coral reef area with varied depths ranging up to 14 m. The proposed models are the ensemble regression tree-fitting algorithm using bagging (BAG), ensemble regression tree-fitting algorithm of least squares boosting (LSB), and support vector regression algorithm (SVR). Data from Landsat 8 and Spot 6 satellite images were used to assess the performance of the proposed models. The three models were used to obtain bathymetric maps using the reflectance of green, red, blue/red, and green/red band ratios. The results were compared with corresponding results yielded by two conventional empirical methods, the neural network (NN) and the Lyzenga generalised linear model (GLM). Compared with echosounder data, BAG, LSB, and SVR results demonstrate higher accuracy ranges from 0.04 to 0.35 m more than Lyzenga GLM. The BAG algorithm, producing the most accurate results, proved to be the preferable algorithm for bathymetry calculation.  相似文献   

The Relationship between Fe Mineralization and Magnetic Basement Faults using Multifractal Modeling in the Esfordi and Behabad Areas (BMD), Central Iran     

Masoumeh NABILOU  Peyman AFZAL  Mehran ARIAN  Ahmad ADIB  Hassan KHEYROLLAHI  Mohammad FOUDAZI  Parviz ANSARIRAD 《《地质学报》英文版》2022,96(2):591-606

Multifractal modeling is a mathematical method for the separation of a high potential mineralized background from a non-mineralized background. The Concentration-Distance to Fault structures (C-DF) fractal model and the distribution of the known iron (Fe) deposits/mines seen in the Esfordi and Behabad 1:100,000 sheets from the Bafq region of central Iran are used to distinguish Fe mineralization based on their distance to magnetic basement structures and surface faults, separately, using airborne geophysical data and field surveys. Application of the C-DF fractal model for the classification of Fe mineralizations in the Esfordi and Behabad areas reveals that the main ones show a correlation with their distance from magnetic basement structures. Accordingly, the distances of Fe mineralizations with grades of Fe higher than 55% )43% < Fe ≤ 60%) are located at a distance of less than 1 km, whereas for surfacial faults with grades of 43% ≤ Fe ≤ 60%, the distances are 3162< DF ≤ 4365 m from the faults. Thus, there is a positive relationship between Fe mineralization and magnetic basement structures. Also, the proximity evidence of Precambrian high-grade Fe mineralization related to magnetic basement structures indicates syn-rifting tectonic events. Finally, this C-DF fractal model can be used for exploration of magmatic and hydrothermal ore deposits.  相似文献