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91.
Temim Deli Mohamed Hbib Ben Atti Rym Zitari-Chatti Khaled Sai Noureddine Chatti 《海洋学报(英文版)》2017,36(12):52-66
The present investigation focuses on population structure analysis of the purple sea urchin Paracentrotus lividus across the African Mediterranean coast, with the main aim of assessing the influence of the Siculo-Tunisian Strait on gene flow disruption in this highly dispersive echinoid species. For this purpose, patterns of morphological and genetic variation were assessed among its populations from the western and eastern Mediterranean coasts. A total of 302 specimens from seven Tunisian sites were collected and examined for morphometric variability at twelve morphometric traits. Concordant results, inferred from CDA (canonical discriminant analyses), pairwise NPMANOVA (non parametric multivariate analysis of variance) comparisons and MDS (multidimensional scaling) plot, unveiled significant inter-population differences in the measured traits among the studied populations. Furthermore, the combined use of the one way ANOSIM (analysis of similarities) and the Discriminant/Hotelling analysis allowed unravelling two morphologically differentiated groups assigned to both western and eastern Mediterranean basins. The SIMPER (similarity percentages) routine analysis showed that total dry weight, test diameter and spine length were major contributors to the morphometric separation between locations and between groups. Pattern of phenotypic divergence discerned in P. lividus across the Siculo-Tunisian Strait is interestingly in congruence with that inferred from the genetic investigation of the purple sea urchin populations from the same region based on the analysis of the mtDNA COI (cytochrome oxidase I) gene in 314 specimens from nineteen locations covering a wider geographic transect, streching westward to the Algerian coast and eastward to the Libyan littoral. The specific haplotypic composition characterizing each Mediterranean basin, as inferred from the minimum spanning network, confirmed the geographic partioning of genetic variation, as revealed by F-statistics and AMOVA (analysis of molecular variance) analyses, yielding significant genetic differentiation between eastern and western Mediterranean populations. The newly detected phylogeographic patterns, observed for the first time in P. lividus throughout the explored distribution range, suggest the involvement of different biotic and abiotic processes in shaping such variation, and provide evidence that a large and geographically exhaustive dataset is necessary to unveil phylogeographic structure within widespread marine species, previously cathegorized as panmictic in part of their distribution range. 相似文献
92.
This study examines spatial and time evolutions of the principal constituents of the
Tunisian background aerosols under Sirocco wind circulations. Aerosols coming from the Sahara
Desert were found to be loaded with particulate matter, especially silicon. The aerosols were
shown to have varying geochemical behaviour along the ``South-North" displacement of the Saharan
plumes, depending on the wind flow characteristics, geomorphologic features and the nature of
soils swept by the wind. In the south and the center part of the country, the transfer of aerosol
constituents to the soil (by gravity and/or impaction) was probably predominated by localized
enrichment phenomena. The latter are reinforced by the effect of turbulent winds over bare soils,
wind wakes and probably selective disintegration, especially in the vicinity of the geomorphologic
features of central Tunisia. These relatively high features, extending over important distances,
appear to be of paramount importance for the phenomena of redistribution of aerosol constituents
even during periods without Sirocco wind circulations. In the northern section of the country,
aerosol constituent concentrations dropped to almost 50%, in spite of the abundance of localized
turbulent winds. This may be explained by the effect of forests and the relatively dense vegetation
cover, which clearly reinforces the transfer phenomena to the soil and the attenuate of dust
entrainment. 相似文献
93.
Petrography, chemistry and genesis of phosphorite concretions in the Eocene Umm Rijam Chert limestone Formation, Ma'an area, south Jordan 总被引：1，自引：0，他引：1
Phosphorite concretions are recorded for the first time within the lower part of the Umm Rijam Chert Limestone Formation (Eocene) in the Ma'an area, southern Jordan. The phosphorite concretions are typically hosted and encountered as individual layer in moderately lithified sediments of marl, chalk and chalky marl. The phosphorite concretions are present in thin layer (10–30 cm thick). They are localized on a hardground surface that formed as a result of cementation of soft ground by bioclastic materials. Light grey and brownish to black colors are encountered with isometric, ellipsoid, elongated, subangular to subrounded phosphorite concretions (up to 6 cm in length). Most of the phosphorite concretions preserve bioturbation structures; they also include fecal pellets of various sizes. The main biogenic components are fragments of macrofossils (bivalves) and microfossils (planktonic foraminifera) in different proportions. Petrographic examinations reveal that the phosphorite concretions are composed of cryptocrystalline apatite that characteristically appears in cross-polarized light almost as isotropic phosphate and minor anisotropic phosphate. Apatite and calcite are the main mineral constituents of the phosphorite concretions identified by XRD. The apatite is identified as francolite (carbonate-flour-apatite). Chemical analyses of the phosphorite concretions using X-ray florescence indicate that the P2O5 content ranges from 18.8 to 31.19%, whereas SEM–EDS analyses indicate that the phosphorus proportion is around 14% by volume. It could be argued that the phosphorite concretions were transported after being reworked, or were derived from carbonate and chalk pebbles that were later phosphatized and subjected to erosion, forming residual lag deposit along the hardground surface. 相似文献
94.
Active faulting and natural hazards in Armenia, eastern Turkey and northwestern Iran 总被引：1，自引：0，他引：1
Arkady S. Karakhanian Vladimir G. Trifonov Herve Philip Ara Avagyan Khaled Hessami Farshad Jamali M. Salih Bayraktutan H. Bagdassarian S. Arakelian V. Davtian A. Adilkhanyan 《Tectonophysics》2004,380(3-4):189-219
Active fault zones of Armenia, SE Turkey and NW Iran present a diverse set of interrelated natural hazards. Three regional case studies in this cross-border zone are examined to show how earthquakes interact with other hazards to increase the risk of natural disaster. In northern Armenia, a combination of several natural and man-made phenomena (earthquakes, landslides and unstable dams with toxic wastes) along the Pambak-Sevan-Sunik fault (PSSF) zone lowers from 0.4 to 0.2–0.3g the maximum permissible level (MPL) of seismic hazard that may induce disastrous destruction and loss of life in the adjacent Vanadzor depression.
In the Ararat depression, a large active fault-bounded pull-apart basin at the junction of borders of Armenia, Turkey, Iran and Azerbaijan, an earthquake in 1840 was accompanied by an eruption of Ararat Volcano, lahars, landslides, floods, soil subsidence and liquefaction. The case study demonstrates that natural hazards that are secondary with respect to earthquakes may considerably increase the damage and the casualties and increase the risk associated with the seismic impact.
The North Tabriz–Gailatu fault system poses a high seismic hazard to the border areas of NW Iran, eastern Turkey, Nakhichevan (Azerbaijan) and southern Armenia. Right-lateral strike–slip motions along the North Tabriz fault have given rise to strong earthquakes, which threaten the city of Tabriz with its population of 1.2 million.
The examples illustrate how the concentration of natural hazards in active fault zones increases the risk associated with strong earthquakes in Armenia, eastern Turkey and NW Iran. This generally occurs across the junctions of international borders. Hence, the transboundary character of active faults requires transboundary cooperation in the study and mitigation of the natural risk. 相似文献
95.
Active faults in the Zagros and central Iran 总被引：1，自引：0，他引：1
D. M. Bachmanov V. G. Trifonov Kh. T. Hessami A. I. Kozhurin T. P. Ivanova E. A. Rogozhin M. C. Hademi F. H. Jamali 《Tectonophysics》2004,380(3-4):221-241
Active tectonic movements in the northwestern Zagros include right lateral slip at the rate of about 10 mm/a along the Main Recent Fault, which inherits the position of the Main Thrust, now inactive, and active thrusting and accompanying folding distributed between several zones southwest of the Main Recent Fault. In the southeastern Zagros (the Fars Province), there are several right lateral faults that extend N–S obliquely to the overall trend of the Zagros fault-and-fold belt. These may be either branches of the Main Recent Fault, or faults accommodating relative broadening of the outer Zagros in its southeastern segment. The Main Thrust in the southeastern Zagros also remains inactive.
The Ipak, North Tehran, and Mosha fault zones and several minor structures in the eastern Alborz form the E–W-trending active fault system with combined reverse and left lateral slip. On the Ipak and Mosha zones, lateral movements with the late Quaternary mean rate exceeding 1 mm/a dominate over vertical fault movements. Together with right lateral faults stretching northeast of Zagros, the faults of the Alborz may accommodate east-directed motion of the Iranian microplate. 相似文献
96.
Integrated Traffic Management Systems (ITMS) need reliable, accurate, and real-time data. Travel time, speed, and delay are
three of the most important factors used in ITMS for monitoring, quantifying, and controlling congestion. GPS has recently
become available for civil applications. Because it provides real-time spatial and time measurements, it has an increasing
use in conducting different transportation studies. This article presents the application of GPS in collecting travel time,
speed, and delay information of 64 major roads in the state of Delaware. A comparative statistical analysis was performed
on data collected by GPS, with data collected simultaneously by the conventional method. The GPS data proved to be at least
as accurate as the data collected by the conventional method, and it was 50% more efficient in terms of manpower. Moreover,
the sample-size requirement was determined to maintain 95% confidence level throughout the controlled test. Benefiting from
the Geographic Information System's dynamic segmentation tool, our travel time, delay, and speed information were integrated
with other relevant traffic data. This was presented graphically on the Internet for public use. Statistical trend analysis
for the data collected in 1997, 1998, 1999, and 2000 are also presented and applications on the overall ITMS are discussed.
? 2002 Wiley Periodicals, Inc. 相似文献
97.
M. J. Hessami S.-M. Phang A. Salleh R. Rabiei 《International Journal of Environmental Science and Technology》2018,15(5):977-992
Limited resources of freshwater and decreasing fossil fuel resources are two main reasons to consider the ocean as a huge resource for producing food, feed, fertilizer and feedstock for fuel. In this study, twenty-nine tropical seaweeds (11 green, 10 red and 8 brown seaweeds) collected in Malaysia were assessed as potential feedstock for bioethanol production. Total carbohydrate content ranged from 12.16 to 71.22% dry weight (DW) with total reducing sugar content ranging from 5.17 to 34.12% DW. During hydrolysis using dilute sulphuric acid, the dominant fermentation inhibitors were 5-hydroxymethylfurfural and phenolic compounds. Overliming was found to reduce the content of fermentation inhibitors by up to 79%. The red seaweeds, Kappaphycus alvarezii (Doty) Doty ex P.C.Silva and Gracilaria manilaensis Yamamoto and Trono, were selected for optimization of saccharification and fermentation of the hydrolysate, because they had the highest carbohydrate contents and are commercially cultivated. The most suitable dilute acid conditions obtained in present study was sulphuric acid (2.5%, w v?1) treatment at 121 °C for 40 min that produced 0.29 and 0.34 g g?1 DW reducing sugar for K. alvarezii and G. manilaensis, respectively. Fermentation of the hydrolysates with Saccharomyces cerevisiae produced bioethanol yields of 20.90 g L?1 (71.0% of theoretical yield) for K. alvarezii and 18.16 g L?1 (67.9% theoretical yield) for G. manilaensis. 相似文献
98.
Hahn Chul Jung James Hamski Michael Durand Doug Alsdorf Faisal Hossain Hyongki Lee A. K. M. Azad Hossain Khaled Hasan Abu Saleh Khan A.K.M. Zeaul Hoque 《地球表面变化过程与地形》2010,35(3):294-304
The Surface Water and Ocean Topography (SWOT) satellite mission will provide global, space‐based estimates of water elevation, its temporal change, and its spatial slope in fluvial environments, as well as across lakes, reservoirs, wetlands, and floodplains. This paper illustrates the utility of existing remote sensing measurements of water temporal changes and spatial slope to characterize two complex fluvial environments. First, repeat‐pass interferometric SAR measurements from the Japanese Earth Resources Satellite are used to compare and contrast floodplain processes in the Amazon and Congo River basins. Measurements of temporal water level changes over the two areas reveal clearly different hydraulic processes at work. The Amazon is highly interconnected by floodplain channels, resulting in complex flow patterns. In contrast, the Congo does not show similar floodplain channels and the flow patterns are not well defined and have diffuse boundaries. During inundation, the Amazon floodplain often shows sharp hydraulic changes across floodplain channels. The Congo, however, does not show similar sharp changes during either infilling or evacuation. Second, Shuttle Radar Topography Mission measurements of water elevation are used to derive water slope over the braided Brahmaputra river system. In combination with in situ bathymetry measurements, water elevation and slope allow one to calculate discharge estimates within 2.3% accuracy. These two studies illustrate the utility of satellite‐based measurements of water elevation for characterizing complex fluvial environments, and highlight the potential of SWOT measurements for fluvial hydrology. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
99.
The ecological processes and interrelationships between protists,either autotrophic or heterotrophic,and environmental factors in mariculture ponds are largely unknown.This study investigated the temporal dynamics of potentially harmful dinoflagellate,Prorocentrum minimum (Pavillard) Schiller,and its relationship to physico-chemical factors and protozoan grazers over a complete cycle in a semi-enclosed shrimp-farming pond near Qingdao,Northern China.P.minimum occurred frequently in low numbers from June to ... 相似文献
100.
The phylogeny of the oligotrich ciliates is currently a hot debate despite the availability of both morphological and molecular
data. In the present paper, further small subunit rRNA (SS rRNA) genes were analyzed from the Genera Omegastrombidium and Novistrombidium, as well as from Strombidium, and combined with three new SS rRNA sequences from Strombidium basimorphum, S. sulcatum population QD-1, and Novistrombidium testaceum population GD. The phylogenetic positions of these organisms were inferred using Bayesian inference, Maximum Likelihood,
and Maximum Parsimony methods. The main results are: (1) the SS rRNA gene sequence analyses match the recent findings about
the molecular evolution of oligotrichs, indicating that the family Strombidiidae is paraphyletic; (2) the Genus Omegastrombidium is separated from the Genus Strombidium, as shown in recent cladistic analyses; (3) morphospecies in Genus Novistrombidium, based on similarity of somatic ciliature, are separated from each other in all topological trees, indicating that this genus
could be a paraphyletic group; (4) the molecular data indicate a possibility of paraphyly for the genus Strombidium; and (5) the similarities of the SS rRNA gene of specimens identified as S. sulcatum and S. inclinatum are 99.8%–100%. However, present knowledge on the oligotrichs sensu stricto is still insufficient and further studies based
on both molecular and other technologies are required. 相似文献