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51.
J. Nouri B. Lorestani N. Yousefi N. Khorasani A. H. Hasani F. Seif M. Cheraghi 《Environmental Earth Sciences》2011,62(3):639-644
This study aims to assess the extent of metal accumulation by plants found in a mining area in Hamedan Province in the central
west part of Iran. It also investigates to find suitable plants for phytoextraction and phytostabilization as two phytoremediation
strategies. Plants with a high bioconcentration factor (BCF) and low translocation factor (TF) have the potential for phytostabilization
while plants with both BCFs and TFs greater than one have the potential to be used for phytoextraction. In this study, shoots
and roots of the 12 plant species and the associated soil samples were collected. The collected samples were then analyzed
by measurement of total concentrations of trace elements (Pb, Zn, Mn and Fe) using atomic absorption spectrophotometer. Simultaneously,
BCF and TF parameters were calculated for each element. Results showed that although samples suitable for phytoextraction
of Pb, Zn, Mn and Fe and phytostabilization of Fe were not detected, Scrophularia scoparia was the most suitable for phytostabilization of Pb, Centaurea virgata,
Echinophora platyloba and Scariola orientalis had the potential for phytostabilization of Zn and Centaurea virgata and Cirsium congestum were the most efficient in phytostabilization of Mn. Present study showed that native plant species growing on contaminated
sites may have the potential for phytoremediation. 相似文献
52.
The presence of heavy metal concentrations was examined in natural sediments from four sites along the Jajrood river in northeast
of Tehran, the capital of Iran. Besides determination of elemental concentrations (Pb, Cu, Zn, Cd, Ni and Cr), X-ray fluorescence
and X-ray diffraction tests were carried out to determine other chemical components in these adsorbents. Also the ability
of sediments to adsorb these heavy metal ions from aqueous solutions was investigated. Results show that the extent of adsorption
increases with increase in adsorbent concentration. The amount of adsorbed Pb, Cu and Zn in sediments was much greater than
that of the other metals, and Cr was adsorbed much less than others. The adsorbabilities of sediments to heavy metals increased
in the order of Pb > Cu > Zn > Cd > Ni > Cr. Based on the adsorption data, equilibrium isotherms were determined at selected
areas to characterize the adsorption process. The adsorption data followed Freundlich and Langmuir isotherms in most cases.
Correlation and cluster analysis was performed on heavy metals adsorption and sediment components at each site to evaluate
main adsorbing compounds in sediments for each metal. Results demonstrated that heavy metals sorption is mostly related to
load of organic matter in the Jajrood river sediments. 相似文献
53.
Bore holes were drilled in the Senonian limestone of the Hedils-Jalta area (northern Tunisia) in order to determine their potential as an aquifer. Structural, tectonic and hydrogeologic data compilation shows the discrimination of productive and not productive zones. Differential hydraulic productivity was recognised with four distinct productive geological zones separated by a sterile corridor trending NW–SE. The structure consists of two compressional dihedrons, limited by two conjugate strike-slip faults, trending NNE–SSW and nearly E–W. The reduction of the (1) potential reservoir, (2) the low hydraulic productivity of the central band, (3) the torsion of the fold axis in eccentric arcs on both sides of the compressive relay and (4) the differential hydrogeological zonation are all related to the distribution of stress in the interference zone between conjugate strike-slip faults and to the reorientation of the stress field in their vicinity. This study constitutes a main database in establishing strategies for groundwater exploration in the similar zones. 相似文献
54.
55.
Effect of combined translation and torsion on undrained uplift capacity of plate anchors: Plastic limit analysis (PLA) solution 
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下载免费PDF全文 Uplift capacity of plate anchors has been the focus of numerous studies, because anchor plates are designed for pull‐out in normal operating conditions. However, the response of plate anchors under 6‐degrees‐of‐freedom loading caused during extreme loading conditions is poorly understood. The purpose of this study is to propose a simple yet sufficiently accurate analytical solution to investigate the behavior of plate anchor under combined in‐plane translation and torsion and to evaluate its effect on the plate uplift bearing capacity. To this end, a modified plastic limit analysis (PLA) approach is introduced and compared with limit equilibrium and simplified upper bound baseline solutions. The proposed method is verified with 3‐dimensional finite element. The variables considered in this study include plate aspect ratio, plate thickness, as well as load direction and eccentricity. Results of analytical solutions indicate the insensitivity of the “shape” of the shear‐torsion yield envelope to plate thickness. This finding facilitates the use of simplified yet reasonable yield envelope for infinitely thin plate obtained from simplified PLA approach for other plate thicknesses. The “size” of the failure envelope (controlled by pure torsional and translational capacity) could be predicted fairly accurately by PLA and limit equilibrium methods. Combination of these analytical methods offers a simple yet reasonably accurate solution to describe shear‐torsion response of anchor plate. The obtained shear‐torsion yield envelope is then fitted in the generalized 6‐degrees‐of‐freedom yield surface which describes the reducing effect of moment, torsion, and planar forces on the uplift capacity of plate. 相似文献
56.
Spatial distribution and biodiversity of macrofauna in the southeast of the Caspian Sea, Gorgan Bay in relation to environmental conditions 总被引：1，自引：0，他引：1
Mehrshad Taheri Maryam Yazdani Foshtomi Majid Noranian Seyed Sahab Mira 《Ocean Science Journal》2012,47(2):113-122
Spatial distribution and biodiversity of macrofauna in the Gorgan Bay, southeast of the Caspian Sea, were studied at fifteen stations in June 2010. Also, depth, temperature, salinity, dissolved oxygen, total organic matter content and sediment particle size were measured in each station. A total 3,356 individuals belonged to eight families and ten species were identified. Polychaeta were numerically dominated groups and Streblospio gynobranchiata, was constant and dominant species with 60.28% of total individuals but Bivalvia with four species had highest species number, though the density of them were low. The maximum density (4,500 ind/m2) was obtained at station 1 while the minimum (411 ind/m2) was observed at station 6. There was not significant correlation between the density of macrofauna with all environmental conditions. In total, six feeding group were considered but surface deposit feeder and deposit feeder were dominant in all stations. The maximum mean species number, diversity, richness, and evenness were obtained, 6.33, 1.46, 1.38 and 0.87, respectively. Based on the M-AMBI and the AMBI classification it seems that bentic environment in Gorgan Bay was not bad but the results of Shannon-Wiener, Margalef and Simpson indices the results were vice versa. In general, the values of the mentioned indices decreased from the western to the eastern part of the bay. Furthermore, the nonmetric multidimensional scaling (nMDS) showed that the structure of the macrofaunal assemblages was divides to six groups. 相似文献
57.
Mineral chemistry of a Cenozoic igneous complex,the Urumieh–Dokhtar magmatic belt,Iran: Petrological implications for the plutonic rocks 下载免费PDF全文
下载免费PDF全文 Maryam Honarmand Nematollah Rashidnejad Omran Franz Neubauer Ghasem Nabatian Mohammad Hashem Emami Manfred Bernroider Jamshid Ahmadian Mohammad Ebrahimi Xiaoming Liu 《Island Arc》2016,25(2):137-153
The Niyasar plutonic complex, one of the Cenozoic magmatic assemblages in the Urumieh‐Dokhtar magmatic belt, was the subject of detailed petrographic and mineralogical investigations. The Niyasar magmatic complex is composed of Eocene to Oligocene mafic rocks and Miocene granitoids. Eleven samples, representing the major rock units in the Niyasar magmatic complex and contact aureole were chosen for mineral chemical studies and for estimation of the pressure, temperature, and oxygen fugacity conditions of mineral crystallization during emplacement of various magmatic bodies. The analyzed samples are composed of varying proportions of quartz, plagioclase, K‐feldspar, hornblende, biotite, titanite, magnetite, apatite, zircon, garnet, and clinopyroxene. Application of the Al‐in‐hornblende barometer indicates pressures of around 0.2 to 0.4 kbar for the Eocene–Oligocene mafic bodies and around 0.5 to 1.7 kbar for the Miocene granitoids. Hornblende‐plagioclase thermometry yields relatively low temperatures (661–780 °C), which probably reflect late stage re‐equilibration of these minerals. The assemblage titanite–magnetite–quartz as well as hornblende composition were used to constrain the oxygen fugacity and H2O content during the crystallization of the parent magmas in the Miocene plutons. The results show that the Miocene granitoids crystallized from magmas with relatively high oxygen fugacity and high H2O content (~5 wt% H2O). The Miocene granitoids show similar range of oxygen fugacity, H2O contents and mineral chemical compositions, which indicate a common source for their magmas. Although the crystallization pressures of the Miocene plutons discriminate various categories of plutonic bodies emplaced at depths of about 5.7–6.5 km (Marfioun pluton), about 4.2 km (Ghalhar pluton) and 1.9–2.3 km (Poudalg pluton), they were later uplifted to the same level by vertical displacement of faults. The emplacement depths of the Niyasar plutons suggest that the central part of the Urumieh‐Dokhtar magmatic belt has experienced an uplift rate of ca. 0.25–0.4 mm/yr from the Miocene onwards. 相似文献
58.
Siti Maryam Yaakub Len J. McKenzie Paul L.A. Erftemeijer Tjeerd Bouma Peter A. Todd 《Marine pollution bulletin》2014
Due to increasing development Southeast Asia’s coastlines are undergoing massive changes, but the associated impacts on marine habitats are poorly known. Singapore, a densely populated island city–state, is a quintessential example of coastal modification that has resulted in the (hitherto undocumented) loss of seagrass. We reconstructed the historic extent and diversity of local seagrass meadows through herbarium records and backwards extrapolation from contemporary seagrass locations. We also determined the current status of seagrass meadows using long-term monitoring data and identified the main threats to their presence in Singapore. Results show that, even though ∼45% of seagrass has been lost during the last five decades, species diversity remains stable. The main cause of seagrass loss was, and continues to be, land reclamation. We conclude that strict controls on terrestrial runoff and pollution have made it possible for seagrass to persist adjacent to this highly urbanised city–state. 相似文献
59.
Aminroayaei Yamini Maryam Tutti Faramarz Aminoroayaei Yamini Mohammad Reza Ahmadian Jamshid Wan Bo 《Mineralogy and Petrology》2017,111(5):747-759
Mineralogy and Petrology - The chloritization of biotite and stable isotopes of silicate have been studied for the Zafarghand porphyry copper deposit, Ardestan, Iran. The studied area, in the... 相似文献
60.
Tayeb Sadeghifar Maryam Nouri Motlagh Massoud Torabi Azad Mahdi Mohammad Mahdizadeh 《Marine Geodesy》2017,40(6):454-465
The prediction of wave parameters has a great significance in the coastal and offshore engineering. For this purpose, several models and approaches have been proposed to predict wave parameters, such as empirical, soft computing, and numerical based approaches. Recently, soft computing techniques such as recurrent neural networks (RNN) have been used to develop sea wave prediction models. In this study, the RNN for wave prediction based on the data gathered and the measurement of the sea waves in the Caspian Sea, in the north of Iran is used for this study. The efficiency of RNNs for 3, 6, and 12 hourly and diurnal wave prediction using correlation coefficients is calculated to be 0.96, 0.90, 0.87, and 0.73, respectively. This indicates that wave prediction by using RNNs yields better results than the previous neural network approaches. 相似文献