Bringing geoheritage underwater: definitions,methods, and application in two Mediterranean marine areas     

A. Rovere  M. Vacchi  V. Parravicini  C. N. Bianchi  N. Zouros  M. Firpo 《Environmental Earth Sciences》2011,64(1):133-142

Within the definition given by UNESCO of World Cultural and Natural Heritage, geoheritage finds its significance both as the geological or geomorphological elements of nature worthy of conservation and as habitat of threatened species of outstanding universal value from the point of view of science or conservation. Definitions, methods, and applications for the conservation and valorization of geoheritage have been proposed for various types of environments, but their application in underwater areas is seldom, if even, reported. In this study, we propose a set of definitions and methods for the evaluation of scientific and additional values in underwater environment, and we apply them in two Mediterranean areas: Sigri (Greece, Lesvos Island) and Bergeggi (Italy, Liguria region). Results show the applicability of the schemes proposed in different geological and geomorphological settings and provide tools for the evaluation of abiotic underwater heritage in the two areas.  相似文献   

Estimation of mean spectral directions in random seas     

Paolo Boccotti  Felice Arena  Vincenzo Fiamma  Alessandra Romolo  Giuseppe Barbaro 《Ocean Engineering》2011,38(2-3):509-518

A method for obtaining the directional spectrum, on assuming that the frequencies of the elementary waves are all different from one another, is re-proposed in a form suitable for applications to sea states near a coast. The method is applied to an interval of 10 h during which the sea state remained basically steady state off the beach at Reggio Calabria (east coast of the Straits of Messina). It is shown that the directional spectrum converges as the length of the time series data grows. A numerical simulation of a 10 h sea state confirms that the directional spectrum converges as the length of the time series grows, and the convergence is onto the known directional spectrum used to make the numerical simulation. Through the numerical simulation, it is proved that the method, generally, is suitable for applications even with short time series of wind waves (duration of about 100T_p). Finally, it is shown that the method is not necessarily inadequate even with short records of multimodal sea states with different modal directions, modal amplitude ratios and intermodal distances.  相似文献   

Orthogonal design for optimization of pigment extraction from surface sediments of the Changjiang River Estuary   总被引：1，自引：0，他引：1  

ZHAO Jun  YAO Peng  YU Zhigang  Thomas S Bianchi 《海洋学报(英文版)》2011,30(4):33-42

Using a suitable solvent for extracting pigments from sediment for high performance liquid chro-matography (HPLC) analysis is critical for obtaining qualitative and quantitative estimates of phytoplanktonic and benthic algal biomass, as well as community composition. Five methodolog-ical factors (sample dehydration, extraction solvent, extraction duration, number of extractions, and ratio of solvent volume: sample weight) were studied using an L₉ (3⁴) orthogonal design in a sedimentary pigment extraction experiment on samples collected from the Changjiang large-river delta-front estuary (LDE), using HPLC analysis. The results show that the optimal extraction method for sedimentary pigments should include freeze-drying samples prior to extraction. The effects of different factors on sedimentary pigment extraction were separated by the L₉ (3⁴) or-thogonal design experiments and showed that the extraction solvent was the most important, with extraction duration the second most important, and numbers of extraction and ratio of solvent vol-ume: sample weight was the least important. The mixed solvent treatment comprised of acetone, methanol and water (80:15:5, by volume) was best for polar pigment extraction, with 100% acetone better for apolar pigments. For most pigments employed in this study (i.e., peridinin, fucoxanthin, alloxanthin, diatoxanthin, zeaxanthin, pheophytin-a and β-carotene), 3 h was found to be enough time for extraction from these deltaic sediments. However, for chlorophyll-a, the most important pigment used for estimating algal biomass, 12 h was needed. A small amount of solvent (3 ml) with duplicate extractions obtained the greatest amount and diversity of pigments. Unfortunately, no extraction method was found to be suitable for all pigments in sediments. The choice of extraction procedure should be made in accordance with the objective of each study, taking into consideration the properties of sediments and pigments in question.  相似文献   

The Galaxy Evolution Explorer (GALEX). Its legacy of UV surveys,and science highlights     

Luciana Bianchi 《Astrophysics and Space Science》2014,354(1):103-112

The Galaxy Evolution Explorer (GALEX) imaged the sky in the Ultraviolet (UV) for almost a decade, delivering the first sky surveys at these wavelengths. Its database contains far-UV (FUV, λ _eff～1528 Å) and near-UV (NUV, λ _eff～2310 Å) images of most of the sky, including deep UV-mapping of extended galaxies, over 200 million source measurements, and more than 100,000 low-resolution UV spectra. The GALEX archive will remain a long-lasting resource for statistical studies of hot stellar objects, QSOs, star-forming galaxies, nebulae and the interstellar medium. It provides an unprecedented road-map for planning future UV instrumentation and follow-up observing programs in the UV and at other wavelengths. We review the characteristics of the GALEX data, and describe final catalogs and available tools, that facilitate future exploitation of this database. We also recall highlights from the science results uniquely enabled by GALEX data so far.  相似文献   

Nuclear obscuration in the high-ionization Seyfert 2 galaxy Tol 0109–383     

K. Iwasawa  G. Matt  A.C. Fabian  S. Bianchi  W.N. Brandt  M. Guainazzi  T. Murayama  Y. Taniguchi 《Monthly notices of the Royal Astronomical Society》2001,326(1):119-125

We report on the BeppoSAX detection of a hard X-ray excess in the X-ray spectrum of the classical high-ionization Seyfert 2 galaxy Tol 0109–383. The X-ray emission of this source observed below 7 keV is dominated by reflection from both cold and ionized gas, as seen in the ASCA data. The excess hard X-ray emission is presumably caused by the central source absorbed by an optically thick obscuring torus with N _H∼2×10²⁴ cm⁻² . The strong cold X-ray reflection, if it is produced at the inner surface of the torus, is consistent with the picture where much of the inner nucleus of Tol 0109–383 is exposed to direct view, as indicated by optical and infrared properties. However, the X-ray absorption must occur at small radii in order to hide the central X-ray source but leave the optical high-ionization emission-line region unobscured. This may also be the case for objects such as the Seyfert 1 galaxy Mrk231.  相似文献   

The XMM–Newton view of Mrk 3 and IXO 30     

Stefano Bianchi  Giovanni Miniutti  rew C. Fabian  Kazushi Iwasawa 《Monthly notices of the Royal Astronomical Society》2005,360(1):380-389

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An application of the Nekhoroshev theorem to the restricted three-body problem     

Alessandra Cellett  Laura Ferrara 《Celestial Mechanics and Dynamical Astronomy》1996,64(3):261-272

We studied the stability of the restricted circular three-body problem. We introduced a model Hamiltonian in action-angle Delaunay variables. which is nearly-integrable with the perturbing parameter representing the mass ratio of the primaries. We performed a normal form reduction to remove the perturbation in the initial Hamiltonian to higher orders in the perturbing parameter. Next we applied a result on the Nekhoroshev theorem proved by Pöschel [13] to obtain the confinement in phase space of the action variables (related to the elliptic elements of the minor body) for an exponentially long time. As a concrete application. we selected the Sun-Ceres-Jupiter case, obtaining (after the proper normal form reduction) a stability result for a time comparable to the age of the solar system (i.e., 4.9 · 10⁹ years) and for a mass ratio of the primaries less or equal than 10^–6.  相似文献   

Weighting of Parts in Compositional Data Analysis: Advances and Applications     

Hron  Karel  Menafoglio  Alessandra  Palarea-Albaladejo  Javier  Filzmoser  Peter  Talská  Renáta  Egozcue  Juan José 《Mathematical Geosciences》2022,54(1):71-93

Mathematical Geosciences - It often occurs in practice that it is sensible to give different weights to the variables involved in a multivariate data analysis—and the same holds for...  相似文献   

The contrasting geochemical message from the New Caledonia gabbronorites: insights on depletion and contamination processes of the sub-arc mantle in a nascent arc setting     

Arianna?Secchiari  Alessandra?MontaniniEmail author  Delphine?Bosch  Patrizia?Macera  Dominique?Cluzel 《Contributions to Mineralogy and Petrology》2018,173(8):66

The New Caledonia ophiolite hosts one of the rare examples of crust-mantle sections built in a nascent arc environment, providing the unique opportunity to investigate the first stages of arc magmatism in a subduction setting. The sequence consists of refractory harzburgites, overlain by ultramafic (dunites and wehrlites) and mafic lithologies (gabbronorites). The gabbronorites occur in the upper part of the sequence as decimetre to metre-size sills. They are mainly formed (??55 to 70 vol%) of Ca-rich plagioclase (An up to 96 mol%) and high Mg# (88–92), Al₂O₃-poor (1.5–2.4 wt%) clinopyroxene (8–20 vol%), often rimmed by interstitial or poikilitic orthopyroxene (6–27 vol%). Mg-rich olivine (3–15 vol%, Fo?=?87–89 mol%) occurs as anhedral, resorbed crystals. Whole rock (WR) compositions exhibit high Mg# (86–92) and strikingly low trace element contents. They own LREE-depleted patterns, with nearly flat (0.82?≤?Dy_N/Yb_N?≤?1.00) and low HREE (Yb_N?=?0.2–0.9) and positive Eu anomalies. Clinopyroxene trace element chemistry mirrors the extreme depletion of the WR. By contrast, FME enrichments are observed for WR and clinopyroxene. Geochemical models show that the gabbronorites crystallized from primitive, ultra-depleted melts bearing evidence of fluid contamination processes, but with significantly different geochemical signatures compared to boninitic rocks worldwide, i.e. lower LREE-MREE, and absence of Nb depletion and Zr–Hf enrichments. Nd isotopes (+?8.2?≤?εNd_i?≤?+?13.1), together with radiogenic Pb isotopic ratios, support an origin from a DMM source variably modified by slab fluids. We propose that the geochemical signature of the New Caledonia gabbronorites reflect emplacement of primitive, non-aggregated, magma batches in the lower fore-arc crust, during the first phases of arc formation.  相似文献   

Mapping a coastal transition in braided systems: an example from the Precipice Sandstone,Surat Basin     

V. Bianchi  F. Zhou  D. Pistellato  M. Martin  S. Boccardo  J. Esterle 《Australian Journal of Earth Sciences》2018,65(4):483-502

The Precipice Sandstone is traditionally interpreted as a braided fluvial deposit that transitions upwards into meandering channel deposits responding to a rise in base level that eventually deposits the overlying alluvial to lacustrine Evergreen Formation. This study found sedimentary evidence of tidal to marine influence within the Precipice Sandstone coincident with avulsion and diversion of the system from southward to northward-flowing channels as the system was transgressed. The north-flowing channels are interpreted to debouch into a shallow restricted marine embayment with tide and wave influence, which provides an alternative insight into this unit and suggests a Lower Jurassic north or northeasterly marine connection. The Precipice Sandstone is a regional aquifer, in places hosts hydrocarbons and has been considered as a storage unit for CO₂ geosequestration. Outcrop analogues can provide geometries to accompany facies interpreted from sedimentary structures that are observable in core, to assist in characterising reservoir heterogeneity.  相似文献