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Accumulation of metals in both sediments and Phragmites australis organs was studied. Samples were collected from seven stations located in Anzali wetland, Iran. The samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that concentration of the studied metals (except As and Cd) were higher in sediments than in P. australis organs. Metal accumulation was found to be significantly (P <0.05) higher in roots than in above-ground organs of P. australis. The bioaccumulation factor (BAF) and the transfer factor (TF) also verified the highest rate of metal accumulation in roots and their reduced mobility from roots to the above-ground organs. Pearson correlation coefficient showed significant relationships between metal concentrations in sediments and those in plant organs. It should be pointed out that sediment and plant samples exhibited higher metal concentrations in eastern and central parts than in western and southern parts of the wetland. The mean concentrations of all studied elements (except for Fe, V and Al) were higher in these sediment samples than in the Earth’s crust and shale. High accumulation of metals in P. australis organs (roots and shoots) is indicative of their high bioavailability in sediments of the wetland. The correlation between metal concentrations in sediments and in P. australis indicates that plant organs are good bioindicators of metal pollution in sediments of Anzali wetland. 相似文献
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Kazem Darvish Bastami Mehrshad Taheri Maryam Yazdani Foshtomi Sarah Haghparast Ali Hamzehpour Hossein Bagheri Marjan Esmaeilzadeh Neda Molamohyeddin 《海洋学报(英文版)》2017,36(10):79-86
Spatial distribution and structure of nematode assemblages in coastal sediments of the southern part of the Caspian Sea were studied in relation to environmental factors. By considering metals, organic matter, Shannon diversity index(H), maturity index(MI) and trophic diversity(ITD), ecological quality status of sediment was also determined. Fifteen nematode species belonging to eleven genera were identified at the sampling sites. Average density of nematode inhabiting in sediment of the studied area was 139.78±98.91(ind. per 15.20 cm~2). According to redundancy analysis(RDA), there was high correlation between metals and some species. Based on biological indicators, the studied area had different environmental quality. Generally, chemical and biological indices showed different results while biological indices displayed similar results in more sites. 相似文献
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Ahmad Abbasnejad Azam Mirzaie Reza Derakhshani Esmat Esmaeilzadeh 《Environmental Earth Sciences》2013,69(8):2549-2557
Bardsir plain is located in the central part of Kerman Province of Iran. The relative prevalence of arsenic-related cancers, the high concentration of arsenic in nearby plains, as well as the recharge of this aquifer through the mountains composed of high-sulfide volcanic rocks have been motivations of the authors to study the concentration of this element in Bardsir plain. Arsenic concentration was measured in 63 groundwater samples using inductively coupled plasma mass spectrometry method. The results were evaluated through iso-concentration maps, correlation diagrams, and multivariate statistical methods. Accordingly, the concentration of arsenic ranges from 1.3 to 464.5 μg/l with an average value of 134.2 μg/l. So, the groundwaters are enriched with arsenic to much higher levels than permitted for than drinking water acceptable level (10 μg/l). The high arsenic levels in groundwaters of Bardsir plain are ascribed to joint influence of decomposition of sulfides present in mountainous volcanic rocks and the mixing with hydrothermal waters in some locations. Supposedly, the prevalence of higher than 8 pH values has enhanced the release of arsenic from Fe-hydroxides generated during sulfide weathering process. 相似文献
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Understanding petrographical, geochemical and electrical properties of rocks is essential for investigating minerals. This paper presents a study of the petrographical, geochemical and A.C. electrical properties of carbonate rock samples. The samples collected show six lithostratigraphic rock units. Electrical properties were measured using a non‐polarizing electrode at room temperature (～20°C) and a relative atmospheric humidity of ～50% by weight in the frequency range from 42 Hz to 5 MHz. The difference in electrical properties between the samples was attributed to the change in composition and texture between the samples. Electrical properties generally change with many factors (grain size, chemical composition, grain shape and facies). The dielectric constant decreases with frequency and increases with conductor composition. The conductivity increases with the increase of conductor paths between electrodes. Many parameters can contribute to the same result of the electrical properties. The main objective of the present study is to shed more light on the relation between the texture and geochemical composition of measured samples (carbonates that contain clays and quartz grains) through electrical laboratory measurements (conductivity and dielectric constant as a function of frequency). 相似文献
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The concept of equivalent linearization, in which the actual nonlinear structure is replaced by an equivalent linear single-degree-of-freedom (SDOF) system, is extended for soil-structure systems in order to consider the simultaneous effects of soil-structure interaction (SSI) and inelastic behavior of the structure on equivalent linear parameters (ELP). This is carried out by searching over a two-dimensional equivalent period–equivalent damping space for the best pair, which can predict the earthquake response of the inelastic soil-structure system with sufficient accuracy. The super-structure is modeled as an elasto-plastic SDOF system whereas the soil beneath the structure is considered as a homogeneous half-space and is replaced by a discrete model. An extensive parametric study is carried out for a wide range of soil-structure systems subjected to a suite of 59 ground motions. The effect of SSI on ELP is studied through introducing a set of non-dimensional key parameters, which define the soil-structure system. It is shown that ELP of soil-structure systems result from a trade-off between SSI effect and nonlinear behavior of the structure. The contribution of each of these two factors depends on the characteristics of the soil-structure system which, in turn, are defined by the introduced non-dimensional key parameters. Moreover, the reliability of the predicted response of soil-structure systems and its sensitivity to deviation from optimal ELP is studied in detail, which sheds light on the consequences of using improper pairs of ELP for interacting systems in the framework of performance-based design of structures. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Taha Rabeh Joao Carvalho Ahmed Khalil Esmat A. El-Aal Ibrahim El-Hemaly 《Acta Geophysica》2011,59(5):1044-1056
When the solar irradiance propagates between the outer magnetospheric regions and the ionosphere, dynamic processes of the
magnetosphere-ionosphere-thermosphere system are affected at the lower end of their paths by the interaction of radiation
with the neutral troposphere. The main target of this work is to investigate the relationship between the diurnal magnetic
field variations resulting from solar activities and the variation in the troposphere temperature. Meteorological and geomagnetic
data acquired from different observatories located in Egypt, Portugal and Slovakia in a long-term and daily-term scales were
analyzed. 相似文献
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