Microbial‐Enhanced Phytoremediation of Lead Contaminated Calcareous Soil by Centaurea cyanus L          下载免费PDF全文

Akbar Karimi  Habib Khodaverdiloo  Mir Hassan Rasouli‐Sadaghiani 《洁净——土壤、空气、水》2018,46(2)

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Theoretical-period characteristics of frame buildings designed under variable levels of seismicity and allowable-drift     

Abou-Elfath  Hamdy  Elhout  Emad 《地震工程与工程振动(英文版)》2020,19(3):669-681

Period equations provided by seismic codes are generally derived by calibration with recorded period data of buildings located in high seismicity regions. These period-equations do not account for either the design level of seismicity or the permissible limit of lateral drift. Buildings designed under high level of seismicity are expected to display higher stiffness and shorter periods than buildings designed under low-to-medium seismicity levels. In addition, buildings designed with high level of permissible lateral-drift are expected to display lower stiffness and longer periods than buildings designed with low level of permissible lateral-drift. In this study, the theoretical fundamental-periods of an ensemble of regular reinforced concrete(RC) and steel moment-resisting frame(MRF) buildings having 3-, 6-, 9-and 12-stories and designed with various levels of seismicity and permissible lateral-drift are evaluated. The obtained outcome indicates the sensitivity of the MRF theoretical-periods to the design seismicity and the permissible lateral-drift. The results also indicate the need for modifying the current period equations to realistically account for the variations in the design seismicity and allowable lateral-drift of MRF buildings.  相似文献   

Assessing the seismic behavior of steel moment frames equipped by elliptical brace through incremental dynamic analysis (IDA)     

Habib Ghasemi Jouneghani  Abbas Haghollahi 《地震工程与工程振动(英文版)》2020,19(2):435-449

Incremental dynamic analysis and nonlinear static pushover analysis are carried out on a performance-based design to determine the seismic demands and capacities of an elliptic braced moment resisting frame (ELBRF). The objective is to assess ductility, overstrength and response modification factors in a modern steel-braced structural system based on incremental dynamic analysis. This integrated system is connected to a beam and column with an appropriate length while providing enough architectural space to allow for an opening without having the common problems associated with architectural spaces in braced systems. Several different classes of buildings are considered on soil type II. Linear dynamic analysis, nonlinear static pushover analysis and incremental nonlinear dynamic analysis related to 12 records from past earthquakes are carried out using OpenSees software. The factors of ductility, overstrength and response modification are calculated for this system. The values of 9.5 and 6.5 are found and suggested only for the response modification factor for ELBRF systems in allowable stress and ultimate limit state methods, respectively. The fragility curves are plotted for the first time for this type of bracing, which contributes to the assessment of building seismic damage.  相似文献   

Predicting the impacts of climate change on the distribution of Moringa peregrina(Forssk.) Fiori-A conservation approach     

Emad A.FARAHAT  Aliaa M.REFAAT 《山地科学学报》2021,(5):1235-1245

Climate change will affect the geographic distribution and richness of species at different spatial and temporal scales. We applied Maximum entropy(MaxEnt) modeling to predict the potential influence of climatic change on the current and future distribution of the important mountainous tree species Moringa peregrina(Forssk.) Fiori. The Maxent model performed better than random models for the species with the training and test AUC(Area Under the receiver-operating characteristic Curve) values of 0.96 and 0.90, respectively. Jackknife test and response curves showed that the distribution of the species negatively correlates with higher altitudes and precipitation in October and November. Moreover, it positively correlates with the total annual precipitation and precipitation in January. Under current and future climatic conditions, our model predicted habitat gains for M. peregrina towards the coastal northern and southern limits of its distribution. The potentially suitable habitats, under future climate projections, are currently characterized by elevations of 1000 m a.s.l. and total annual precipitation of 80-225 mm/year. Moderate and high potential habitat suitability will increase by 5.6%-6% and 2.1%-2.3%, under RCP2.6 and RCP4.5 scenario, respectively. The results indicated that the habitat suitability of M. peregrina would increase with increasing climate warming, particularly under RCP2.6 scenario. We recommend sustainable conservation and cultivation of Moringa peregrina in its current habitats along the Red Sea mountains.  相似文献   

Effects of vegetation cover on summer climate in China during 1982–2001     

Aziz Salim Habib  Xiaoling Chen  Jianya Gong  Li Zhang 《地球空间信息科学学报》2009,12(1):41-45

In this paper, we apply lagged correlation analysis to study the effects of vegetation cover on the summer climate in different zones of China, using NOAA/AVHRR normalized difference vegetation index (NDVI) data during the time period from 1982 to 2001 and climate data of 365 meteorological stations across China (precipitation from 1982 to 2001 and temperature from 1982 to 1998). The results show that there are positive correlations between spring NDVI and summer climate (temperature and precipitation) in most zones of China; these suggest that, when the vegetation cover increases, the summer precipitation will increase, and the lagged correlations show a significant difference between zones. The stronger correlations between NDVI in previous season and summer climate occur in three zones (Mid-temperate zone, Warm-temperate zone and Plateau climate zone), and this implies that vegetation changes have more sensitive feedback effects on climate in the three zones in China. Supported by the National 973 Program of China (No.2006CB701300), the National Natural Science Foundation of China (No.40721001), the Sino-Germany Joint Project (No. 2006DFB91920), the Open Fund of Shanghai Leading Academic Discipline Project (T0102) and the Open Fund of LIESMARS, Wuhan University.  相似文献   

Denitrification in coastal Louisiana: A spatial assessment and research needs     

Victor H. Rivera-Monroy  Peter Lenaker  Robert R. Twilley  Ronald D. Delaune  Charles W. Lindau  William Nuttle  Emad Habib  Robinson W. Fulweiler  Edward Castañeda-Moya 《Journal of Sea Research》2010,63(3-4):157-172

By transforming fixed nitrogen (N) into nitrogen gas, the biochemical processes that support denitrification provide a function critical to maintaining the integrity of ecosystems subjected to increased loading of N from anthropogenic sources. The Louisiana coastal region receives high nitrate (NO₃^?) concentrations (> 100 µM) from the Mississippi–Ohio–Missouri River Basin and is also an area undergoing high rates of wetland loss. Ongoing and anticipated changes in the Louisiana coastal region promise to alter biogeochemical cycles including the net rate of denitrification by ecosystems. Projecting what these changes could mean for coastal water quality and natural resources requires an understanding of the magnitude and patterns of variation in denitrification rates and their connection to estuarine water quality at large temporal and spatial scales under current conditions. We compile and review denitrification rates reported in 32 studies conducted in a variety of habitats across coastal Louisiana during the period 1981– 2008. The acetylene inhibition and ¹⁵N flux were the preferred techniques (95%); most of the studies used sediment slurries rather than intact sediment cores. There are no estimates of denitrification rates using the N₂/Ar ratio and isotope pairing techniques, which address some of the problems and limitations of the acetylene inhibition and ¹⁵N flux techniques. These studies have shown that sediments from estuaries, lakes, marshes, forested wetlands, and the coastal shelf region are capable of high potential denitrification rates when exposed to high NO₃^? concentrations (> 100 µM). Maximum potential denitrification rates in experimental and natural settings can reach values > 2500 µmol m² h^? 1. The lack of contemporary studies to understand the interactions among critical nitrogen transformations (e.g., organic matter mineralization, immobilization, aquatic plant assimilation, nitrification, nitrogen fixation, dissimilatory nitrate reduction to ammonium (DNRA) and anaerobic ammonium oxidation (annamox) limits our understanding of nitrogen cycling in coastal Louisiana, particularly the role of respiratory and chemolithoautotrophic denitrification in areas undergoing wetland restoration.  相似文献   

Diurnal changes in bacterial communities in oxic surface and hypoxic middle seawater layers of the Changjiang River Estuary     

Yan Huang  Lei Yuan  Yingping Fan  Habib U Rehman Jakhrani  Jianxin Wang 《海洋学报(英文版)》2021,40(4):92-106

The Changjiang River Estuary(CRE) in the East China Sea suffers from seasonal hypoxia in summer. The vertical distributions and seasonal changes of microbial communities in the CRE were well documented. However, little is known about the diurnal changes of bacterial communities in the hypoxic zone of the CRE. Here, 16 S rRNA gene analysis was used to explore the changes of bacterial communities in the oxic surface and hypoxic middle seawater layers during 24 h in the CRE. Significant differences between the hypoxic and oxic layers were observed:the phyla Cyanobacteria, Bacteroidetes and Acidimicrobiia were enriched in the oxic layer, whereas the phylum SAR406 and the class Deltaproteobacteria were more abundant in the hypoxic layer. In addition, some subtle diurnal variations of the bacterial relative abundance were found in both two layers. The relative abundance of Synechococcus increased at night, and this change was more obvious in the hypoxic layer. The similar trend was also found in some phototrophic and several heterotrophic bacteria, such as Rhodobacteraceae, OM60 and Flavobacteriaceae. Their relative abundances peaked at 16:00 in the oxic layer, while the relative abundances peaked at around 7:00 and decreased until 13:00 in the hypoxic layer. Together, the results of the present study suggest that some photosynthetic bacteria and several heterotrophic bacteria have similar diurnal variations implying the light and physicochemical heterogeneity in the course of a day are important for bacterial diurnal changes in the CRE.  相似文献   

Distribution of the plankton assemblages during the winter and summer along the southern coast of the Kerkennah Islands (Tunisia,Eastern Mediterranean Sea)          下载免费PDF全文

Amira Rekik  Habib Ayadi  Jannet Elloumi 《Marine Ecology》2018,39(2)

We studied the distribution of microphytoplankton, ciliates and mesozooplankton in relation to environmental factors in the coastal waters around the Kerkennah Islands. Diatom species were more abundant in winter, representing 74% of the total microphytoplankton abundance, whereas dinoflagellate abundance was higher in summer (58%). Naked ciliates dominated during the winter (73%) and loricate ciliates dominated during the summer (67%). Copepods were the most abundant mesozooplankton group present during the entire period of study, comprising 93%–98% of the total mesozooplankton community. The results indicate that (i) species distribution differed significantly between winter and summer, (ii) environmental factors such as temperature, salinity and nutrients influenced plankton assemblages; and (iii) the highest abundance of several pollution indicator species was due to direct exposure to the polluted coast of Sfax and the effect of tidal asymmetries generating nutrient‐rich inputs from the city.  相似文献   

The Fukang pallasite: Characterization and implications for the history of the Main‐group parent body     

Daniella N. DellaGiustina  Namrah Habib  Kenneth J. Domanik  Dolores H. Hill  Dante S. Lauretta  Yulia S. Goreva  Marvin Killgore  Yang Hexiong  Robert T. Downs 《Meteoritics & planetary science》2019,54(8):1781-1807

We report the results of a study of the Fukang pallasite that includes measurements of bulk composition, mineral chemistry, mineral structure, and petrology. Fukang is a Main‐group pallasite that consists of semiangular olivine grains (Fo 86.3) embedded in an Fe‐Ni matrix with 9–10 wt% Ni and low‐Ir (45 ppb). Olivine grains sometimes occur in large clusters up to 11 cm across. The Fe‐Ni phase is primarily kamacite with accessory taenite and plessite. Minor phases include schreibersite, chromite, merrillite, troilite, and low‐Ca pyroxene. We describe a variety of silicate inclusions enclosed in olivine that contain phases rarely or not previously reported in Main‐group pallasites, including clinopyroxene (augite), tridymite, K‐rich felsic glass, and an unknown Ca‐Cr silicate. Pressure constraints determined from tridymite (<0.4 GPa), two‐pyroxene barometry (0.39 ± 0.07 GPa), and geophysical calculations that assume pallasite formation at the core–mantle boundary (CMB), provide an upper estimate on the size of the Main‐group parent body from which Fukang originated. We conclude that Fukang originated at the CMB of a large differentiated planetesimal 400–680 km in radius.  相似文献   

Pétrographie et géochimie comparées des pellets phosphatés et de leur gangue dans le gisement phosphaté de Ras-Draâ (Tunisie). Implications sur la genèse des pellets phosphatés     

Aida Ben Hassen  Jean Trichet  Jean-Robert Disnar  Habib Belayouni 《Swiss Journal of Geoscience》2010,103(3):457-473

Paléocène-Early Eocene phosphate outcrop in the Ras-Draâ deposit (Tunisia) comprises alternances of P-rich strata (P₂O₅ ≥ 18%) and P-poor ones (P₂O₅ ≤ 2%). In phosphate rich strata, P is concentrated in rounded grains—so-called pellets—(28% ≤ P₂O₅ ≤ 38%) embedded in a matrix—so-called exogangue—much poorer in P (P₂O₅ # 7%) than pellets. The study of pellets (whose size lies mainly between 100 and 500 μm), of their surrounding matrix and of poorly phosphatic sediments, interlayered between the phosphatic strata, has been performed by optical microscopy and various chemical analyses, ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) and punctual chemical analyses by EDS (Energy Dispersive Spectroscopy). Mineralogical and chemical studies of the Tunisian phosphatic pellets show that the basic mineralogical component of these grains is carbonate-fluor-apatite, or francolite. The structural formula of a representative specimen of francolite in the basin is as follows: (Ca_4.63Mg_0.13Na_0.22)(PO₄)_2.51(CO₃)_0.48(OH_0.77F_0.23). The mineralogy of the constituents of the sediment surrounding pellets comprises carbonates, clays, silica (opal, quartz). Microscopic observations of Ras-Draâ phosphorites, added to geochemical results, establish that pellets are small bodies, allochtonous to their matrix and whose composition is independent of that of this matrix. Fecal cylindrical bodies and subspherical pellets, the latest being supposed to proceed from the fecal bodies by fragmentation, are considered to have been formed by fishes, as P-rich and organic matter-rich faeces. These faeces turn out to be resistant to mechanical dispersion and to chemical diffusion of soluble elements from and in direction of sea water. This closeness is responsible for the strong reducing conditions having prevailed inside and during the pellets diagenesis.  相似文献