The trade of live crustaceans in Portugal: space for technological improvements     

Barrento  Sara; Marques  Antonio; Pedro  Sonia; Vaz-Pires  Paulo; Nunes  Maria Leonor 《ICES Journal of Marine Science》2008,65(4):551-559

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Low reproductive success for copepods during a bloom of the non‐aldehyde‐producing diatom Cerataulina pelagica in the North Adriatic Sea     

Adrianna Ianora  Raffaella Casotti  Mauro Bastianini  Christophe Brunet  Giuliana D’Ippolito  Francesco Acri  Angelo Fontana  Adele Cutignano  Jefferson T. Turner  Antonio Miralto 《Marine Ecology》2008,29(3):399-410

Egg production rates and/or hatching success in the copepods Acartia clausi, Calanus helgolandicus and Temora longicornis were negatively affected by a late spring (May–June 2003) phytoplankton bloom in the North Adriatic Sea, dominated mainly by the large diatom Cerataulina pelagica. Highest total concentrations of 3.3·10⁴ cells·ml^?1 were located in the vicinity of the Po River, which also corresponded to the area where the highest numbers of phaeophorbides were measured (0.779, 0.528 and 0.419 μg·l^?1, respectively, compared to an average of the remaining stations of 0.183 ± 0.049 SD), suggesting some grazing on the bloom. Phytoplankton biomass in terms of carbon was dominated by diatoms, representing on average 42% of total phytoplankton carbon and more than 80% at several stations. Cerataulina pelagica, Cyclotella spp., Chaetoceros spp. and small unidentified centric diatoms dominated the diatom community numerically but C. pelagica was by far the dominant diatom in terms of carbon due to its large cell size. This species represented more than 60% of the diatom biomass at nine of the 14 stations sampled, and was absent only at one station, which was the most offshore station sampled during the cruise. Although polyunsaturated aldehydes (PUAs) were not detected, other oxylipins which are hydroxy and keto derivatives of eicosapentaenoic and docosahexaenoic acids that affect copepod reproduction were found in these samples. Hence, we can attribute the negative impact of diatoms not only to PUAs, as previously believed, but also to these compounds. This is the first direct evidence of the presence of oxylipins other than PUAs in marine blooms dominated by diatoms.  相似文献   

Diagnosis of trace metal contamination in sediments: the example of Ensenada and El Sauzal, two harbors in Baja California, Mexico   总被引：1，自引：0，他引：1  

Huerta-Diaz MA  Delgadillo-Hinojosa F  Hernández-Ayón M  Segovia-Zavala JA  García-Esquivel Z  López-Zárate H  Siqueiros-Valencia A  Galindo-Bect S 《Marine environmental research》2008,66(3):345-358

Total metal concentrations in sediments from within Ensenada and El Sauzal Harbors are generally higher than at the mouths. Grain-size analyses suggested that this enrichment could be due to the presence of fine-grained sediments in the inner part of the harbors rather than to anthropogenic perturbations. The (Me/Al)(sample) ratios for Pb, Co, Ni and Fe were significantly higher for Ensenada Harbor relative to El Sauzal Harbor, whereas the ratios for Cd, Mn, Zn and Cu were statistically equivalent for both harbors. Calculated enrichment factors [EF(Me)=(Me/Al)(sample)/(Me/Al)(shale)] indicated that the metals showing slight enrichment were those associated with anthropogenic contamination (Pb, Zn), or probably related to primary productivity in the water column (Cd, Co). The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake.  相似文献   

Vorticity analysis of the Palmi shear zone mylonites: new insights for the Alpine tectonic evolution of the Calabria–Peloritani terrane (southern Italy)     

Vincenzo Festa  Giacomo Prosser  Alfredo Caggianelli  Antonietta Grande  Antonio Langone  Daniela Mele 《Geological Journal》2016,51(4):670-681

New microstructural data on the mylonites from the well‐exposed Palmi shear zone (southern Calabria) are presented with the aim to shed light on both the kinematics and the geometry of the southwestern branch of the Alpine belt during Eocene. In the study area, located between the Sardinia–Corsica block and the Calabria–Peloritani terrane, previous large‐scale geodynamic reconstructions suggest the presence of strike–slip or transform fault zones dissecting the southwestern branch of the Alpine belt. However, there are no field data supporting the occurrence of these structures. This paper uses vorticity analysis technique based on the aspect ratio and the long axis orientation of rigid porphyroclasts in mylonitic marbles and mylonitic granitoids, to estimate the contribution of pure and simple shear of deformation during the movement of the Palmi shear zone. Porphyroclasts aspect ratio and orientation were measured on thin sections using image analysis. Estimates of the vorticity number, W_m, indicate that the Palmi shear zone recorded general shear with a contribution of pure shear of c. 65%. Then, the Palmi shear zone can be interpreted as a segment of a left‐lateral transpressive bend along the southern termination of the Eocene Alpine front. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Wind Statistics from a Forested Landscape     

Johan Arnqvist  Antonio Segalini  Ebba Dellwik  Hans Bergström 《Boundary-Layer Meteorology》2015,156(1):53-71

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POLARIX: a pathfinder mission of X-ray polarimetry     

Enrico Costa  Ronaldo Bellazzini  Gianpiero Tagliaferri  Giorgio Matt  Andrea Argan  Primo Attinà  Luca Baldini  Stefano Basso  Alessandro Brez  Oberto Citterio  Sergio Di Cosimo  Vincenzo Cotroneo  Sergio Fabiani  Marco Feroci  Antonella Ferri  Luca Latronico  Francesco Lazzarotto  Massimo Minuti  Ennio Morelli  Fabio Muleri  Lucio Nicolini  Giovanni Pareschi  Giuseppe Di Persio  Michele Pinchera  Massimiliano Razzano  Luigia Reboa  Alda Rubini  Antonio Maria Salonico  Carmelo Sgro’  Paolo Soffitta  Gloria Spandre  Daniele Spiga  Alessio Trois 《Experimental Astronomy》2010,28(2-3):137-183

Since the birth of X-ray astronomy, spectral, spatial and timing observation improved dramatically, procuring a wealth of information on the majority of the classes of the celestial sources. Polarimetry, instead, remained basically unprobed. X-ray polarimetry promises to provide additional information procuring two new observable quantities, the degree and the angle of polarization. Polarization from celestial X-ray sources may derive from emission mechanisms themselves such as cyclotron, synchrotron and non-thermal bremsstrahlung, from scattering in aspheric accreting plasmas, such as disks, blobs and columns and from the presence of extreme magnetic field by means of vacuum polarization and birefringence. Matter in strong gravity fields and Quantum Gravity effects can be studied by X-ray polarimetry, too. POLARIX is a mission dedicated to X-ray polarimetry. It exploits the polarimetric response of a Gas Pixel Detector, combined with position sensitivity, that, at the focus of a telescope, results in a huge increase of sensitivity. The heart of the detector is an Application-Specific Integrated Circuit (ASIC) chip with 105,600 pixels each one containing a full complete electronic chain to image the track produced by the photoelectron. Three Gas Pixel Detectors are coupled with three X-ray optics which are the heritage of JET-X mission. A filter wheel hosting calibration sources unpolarized and polarized is dedicated to each detector for periodic on-ground and in-flight calibration. POLARIX will measure time resolved X-ray polarization with an angular resolution of about 20 arcsec in a field of view of 15 × 15 arcmin and with an energy resolution of 20% at 6 keV. The Minimum Detectable Polarization is 12% for a source having a flux of 1 mCrab and 10⁵ s of observing time. The satellite will be placed in an equatorial orbit of 505 km of altitude by a Vega launcher. The telemetry down-link station will be Malindi. The pointing of POLARIX satellite will be gyroless and it will perform a double pointing during the earth occultation of one source, so maximizing the scientific return. POLARIX data are for 75% open to the community while 25% + SVP (Science Verification Phase, 1 month of operation) is dedicated to a core program activity open to the contribution of associated scientists. The planned duration of the mission is one year plus three months of commissioning and SVP, suitable to perform most of the basic science within the reach of this instrument. A nice to have idea is to use the same existing mandrels to build two additional telescopes of iridium with carbon coating plus two more detectors. The effective area in this case would be almost doubled.  相似文献   

Particulate organic matter uptake rates of two benthic filter-feeders (Sabella spallanzanii and Branchiomma luctuosum) candidates for the clarification of aquaculture wastewaters     

Cavallo D  Pusceddu A  Danovaro R  Giangrande A 《Marine pollution bulletin》2007,54(5):622-625

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TitaniQ under pressure: the effect of pressure and temperature on the solubility of Ti in quartz   总被引：5，自引：2，他引：3  

Jay B. Thomas  E. Bruce Watson  Frank S. Spear  Philip T. Shemella  Saroj K. Nayak  Antonio Lanzirotti 《Contributions to Mineralogy and Petrology》2010,160(5):743-759

Quartz and rutile were synthesized from silica-saturated aqueous fluids between 5 and 20 kbar and from 700 to 940°C in a piston-cylinder apparatus to explore the potential pressure effect on Ti solubility in quartz. A systematic decrease in Ti-in-quartz solubility occurs between 5 and 20 kbar. Titanium K-edge X-ray absorption near-edge structure (XANES) measurements demonstrate that Ti⁴⁺ substitutes for Si⁴⁺ on fourfold tetrahedral sites in quartz at all conditions studied. Molecular dynamic simulations support XANES measurements and demonstrate that Ti incorporation onto fourfold sites is favored over interstitial solubility mechanisms. To account for the P–T dependence of Ti-in-quartz solubility, a least-squares method was used to fit Ti concentrations in quartz from all experiments to the simple expression

RTlnX\textTiO 2 \textquartz = - 60952 + 1.520 ·T(K) - 1741 ·P(kbar) + RTlna\textTiO 2 RT\ln X_{{{\text{TiO}}_{ 2} }}^{\text{quartz}} = - 60952 + 1.520 \cdot T(K) - 1741 \cdot P(kbar) + RT\ln a_{{{\text{TiO}}_{ 2} }}  相似文献    119. Eustatic and tectonic controls on Quaternary Ras Leona marine terraces (Strait of Gibraltar, northern Morocco)      Khalil El Kadiri  Antonio Pedrera  Ramón Julià 《Quaternary Research》2010,74(2):277-113 Well-preserved Quaternary staircased marine terraces appear on Ras Leona limestone relief. This is a peculiar sector of the Betic-Rif Cordillera, lying in the four-way junction between the Atlantic and the Mediterranean, and Europe and Africa. The age and altitude correlation of the Ras Leona terraces with travertine-covered lateral equivalent terraces fashioned in the neighbouring Beni Younech area, and comparison with those along the Moroccan Atlantic coasts, would suggest that the Ras Leona terraces were mainly formed by eustatic factors. The importance of the eustasy is supported by further comparisons with Spanish and Moroccan Mediterranean terraces and with different marine terraces developed on passive-margin coasts around the world. A tectonic event occurred mainly during the period between the formation of the Maarifian and the Ouljian terraces (i.e., between 370 and 150 ka). The moderate Quaternary tectonic uplift deduced from the marine terraces and its comparison with uplifted marine terraces developed in active subduction setting disagrees with the model of an active eastwards subduction below the Gibraltar tectonic arc.  相似文献    120. Rhizosphere and flooding regime as key factors for the mobilisation of arsenic and potentially harmful metals in basic,mining-polluted salt marsh soils      Antonio María-Cervantes  Héctor M. ConesaMaría Nazaret González-Alcaraz  José Álvarez-Rogel 《Applied Geochemistry》2010 The occurrence of mining areas in the vicinities of salt marshes may affect their ecological functions and facilitate the transfer of pollutants into the food chain. The mobilisation of metals in salt marsh soils is controlled by abiotic (pH, redox potential) and biotic (influence of rhizosphere) factors. The effect of the rhizosphere of two plant species (Sarcocornia fruticosa and Phragmites australis) and different flooding regimes on potentially harmful metals and As mobilisation from salt marsh soil polluted by mining activities were investigated (total concentrations: 536 mg kg−1 As, 37 mg kg−1 Cd, 6746 mg kg−1 Pb, 15,320 mg kg−1 Zn). The results show that the changes in redox conditions (from 300 mV to −100 mV) and pH after flooding and rewetting periods may mobilise the contaminant elements into soil solution (e.g., 100 μg L−1 Cd, 30 μg L−1 Pb, 7 mg L−1 Zn), where they are available for plants or may be leached from the soil. Drying periods generated peaks of concentrations in the soil solution (up to 120 μg L−1 Cd and 50 μg L−1 Pb). The risk assessment of As and metal-polluted salt marshes should take into account flood dynamics in order to prevent metal(loid) mobilisation.  相似文献    [首页] « 上一页 [7] [8] [9] [10] [11] 12 [13] [14] [15] [16] [17] 下一页 » 末  页»