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131.
Anthropogenic activities have become an important source of heavy metals to the marine environments. Biological sentinels like seabirds’ chicks have been widely used to monitorize the levels of some heavy metals. Due to its mainly marine foraging habits, Audouin’s gull fits well for this purpose. Mercury and lead levels were measured in mantle feathers of Audouin’s gull chicks from two colonies in NE Iberian Peninsula: the Ebro Delta and the Llobregat Delta. Both are anthropized areas subject to differential pollutant inputs. Lead levels were significantly higher in the Llobregat Delta probably due to the use of leaded fuel in the nearby Barcelona airport. On the other side, mercury concentrations were higher in the Ebro Delta, in relation with the disposal of the toxic sediments at the Flix site carried down by the Ebro River. These mercury levels in the Ebro chicks reached values that have been described as toxic. 相似文献
132.
Jose Ramon B. Cantalice Moacyr Cunha Filho Borko D. Stosic Victor Casimiro Piscoya Sergio M. S. Guerra Vijay P. Singh 《水文科学杂志》2013,58(8):1789-1802
AbstractSuspended sediment and bedload discharges in sand-bed rivers shape semi-arid landscapes and impact sediment delivery from these landscapes, but are still incompletely understood. Suspended sediment and bedload fluxes of the intermittent Exu River, Brazil, were sampled by direct measurements. The highest suspended sediment concentration observed was 4847.4 mg L-1 and this value was possibly associated with the entrainment of sediment that was deposited in the preceding year. The bedload flux was well related to the stream power and the river efficiently transported all available bedload with a mean rate of 0.0047 kg m-1 s-1, and the percentage of bedload to suspended sediment varied between 4 and 12.72. The bed sediment of Exu River was prone to entrainment and showed a proclivity for transport. Thus, sand-bed and gravel-bed rivers of arid environments seem to exhibit the same mobility in the absence of armour layer.Editor D. Koutsoyiannis; Associate editor B. TouaibiaCitation Cantalice, J.R.B., Cunha Filho, M., Stosic, B.D., Piscoya, V.C., Guerra, S.M.S., and Singh, V.P., 2013. Relationship between bedload and suspended sediment in the sand-bed Exu River, in the semi-arid region of Brazil. Hydrological Sciences Journal, 58 (8), 1789–1802. 相似文献
133.
Eloisa Di Sipio Antonio Galgaro Elisa Destro Giordano Teza Sergio Chiesa Aurelio Giaretta Adele Manzella 《Environmental Earth Sciences》2014,72(5):1383-1401
Determining the suitability of a local area at a regional or local scale for the geothermal application of low enthalpy systems requires the knowledge of rock thermal conductivity values to evaluate the possibility of low-enthalpy heat exchange. A digital cartographic tool is also needed to synthesize the thermal properties of the underground. This tool should be easily accessible and upgradeable and thus suitable for territorial planning and environmental control. In order to address these key issues, a methodological approach was developed within the framework of the national VIGOR Project, dedicated to evaluating the geothermal potential in southern Italy. In this paper the region of Calabria was selected as a case study. Around 70 samples that were representative of the main geological formations were collected from all over the area. Thermal property tests were carried out both in dry and wet conditions, using a thermal device in accordance with the modified transient plane source method. The thermal conductivity values were then compared with data from the international literature. In order to consider the influence of the entire stratigraphic sequence on the thermal conductivity parameters, a geostatistical analysis of the available lithostratigraphic data was performed using the MATLAB toolbox Modalstrata, specially developed for this purpose. A comprehensive geothermal subsurface characterization of Calabria was thus obtained. 相似文献
134.
The San Martín shield volcano, located in the Los Tuxtlas Volcanic Field, has experienced effusive shield-building activity, as well as explosive eruptions, as evidenced by direct observations during the last eruption in 1793. The threat to the surrounding villages consists principally of lahars, especially because of the tropical climate in the region. Ash fallout and lava flows represent additional hazards. In addition, the surrounding Quaternary monogenetic field includes more than 300 scoria cones and about 40 explosion craters (mainly maars) that also represent a hazard source. In the present study we constructed hazard maps using field data, orthophotos, spatial analysis, and specialized software (LAHARZ and HAZMAP) to deliminate lahar inundation zones, areas that could potentially be affected by ash fallout (including the evaluation of houses prone to roof collapse due to ash load), and the most susceptible areas for hosting future monogenetic vent formation. 相似文献
135.
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137.
Ariadna Farrés Jacques Laskar Sergio Blanes Fernando Casas Joseba Makazaga Ander Murua 《Celestial Mechanics and Dynamical Astronomy》2013,116(2):141-174
Using a Newtonian model of the Solar System with all 8 planets, we perform extensive tests on various symplectic integrators of high orders, searching for the best splitting scheme for long term studies in the Solar System. These comparisons are made in Jacobi and heliocentric coordinates and the implementation of the algorithms is fully detailed for practical use. We conclude that high order integrators should be privileged, with a preference for the new $(10,6,4)$ method of Blanes et al. (2013). 相似文献
138.
Eleonora Ammannito M. Cristina De Sanctis Fabrizio Capaccioni M. Teresa Capria F. Carraro Jean‐Philippe Combe Sergio Fonte Alessandro Frigeri Steven P. Joy Andrea Longobardo Gianfranco Magni Simone Marchi Thomas B. McCord Lucy A. McFadden Harry Y. McSween Ernesto Palomba Carle M. Pieters Carol A. Polanskey Carol A. Raymond Jessica M. Sunshine Federico Tosi Francesca Zambon Christopher T. Russell 《Meteoritics & planetary science》2013,48(11):2185-2198
We present global lithological maps of the Vestan surface based on Dawn mission's Visible InfraRed (VIR) Spectrometer acquisitions with a spatial sampling of 200 m. The maps confirm the results obtained with the data set acquired by VIR with a spatial sampling of 700 m, that the reflectance spectra of Vesta's surface are dominated by pyroxene absorptions that can be interpreted within the context of the distribution of howardites, eucrites, and diogenites (HEDs). The maps also partially agree with the ground and Hubble Space Telescope observations: they confirm the background surface being an assemblage of howardite or polymict eucrite, as well as the location of a diogenitic‐rich spot; however, there is no evidence of extended olivine‐rich regions in the equatorial latitudes. Diogenite is revealed on the Rheasilvia basin floor, indicating that material of the lower crust/mantle was exposed. VIR also detected diogenites along the scarp of Matronalia Rupes, and the rims of Severina and a nearby, unnamed crater, and as ejecta of Antonia crater. The diogenite distribution is fully consistent with petrological constraints; although the mapped distribution does not provide unambiguous constraints, it favors the hypothesis of a magma ocean. 相似文献
139.
Juan I. Larruquert José Antonio Méndez José Antonio Aznárez Manuela Vidal-Dasilva Sergio García-Cortés Luis Rodríguez-de Marcos Mónica Fernández-Perea 《Astrophysics and Space Science》2011,333(1):305-309
The interaction between Ricci scalar curvature and the baryon number current, dynamically breaks CPT in an expanding universe
and leads to baryon asymmetry. Using this kind of interaction and study the gravitational baryogenesis in the Bianchi type
I universe. We find out the effect of anisotropy of the universe on the baryon asymmetry for the case which the equation of
state parameter, ω, varies with time. 相似文献
140.
We evaluate the evidence for the presence of mineral spectral signatures indicative of the past presence of water at two putative paleolakes on Mars using observations by the Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Image Spectrometer for Mars (CRISM). CRISM spectra of both sites are consistent with laboratory spectra of Mg-rich phyllosilicates. Our analysis represents the first detailed evaluation of these locations. The spatial occurrence and association with topographic features within the craters is distinctly different for the two sites. The occurrence of these minerals supports the conclusion that water was once active in the areas sampled by these craters. The distribution of the phyllosilicates in Luqa does not provide distinctive evidence for the presence of a previous standing body of water and is consistent with either impact emplacement or post-impact alteration. For Cankuzo, the phyllosilicate distribution provides evidence of a layer in the crater wall indicative of aqueous activity, but does not require a paleolake. 相似文献