PCDD and PCDF intake through consumption of locally produced seafood by Venice lagoon residents: elements for risk management     

Miniero R  Ceretti G  Cherin E  Dellatte E  De Luca S  Ferri F  Fulgenzi AR  Grim F  Iacovella N  Iamiceli AL  Ingelido AM  Vio P  di Domenico A 《Marine pollution bulletin》2005,50(12):1727-1732

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Composition of organic matter in subducted and unsubducted sediments off the Nicoya peninsula, Costa Rica (ODP Leg 170, Sites 1039 and 1040)     

Rüdiger Lutz  Birgit Gieren  Andreas Lückge  Heinz Wilkes  Ralf Littke 《Organic Geochemistry》2000,31(12)

Investigation of sediment samples from Sites 1039 and 1040 (ODP Leg 170) drilled off the Nicoya peninsula (Costa Rica) by organic geochemical and organic petrological methods has revealed that subduction has only little influence on the composition of the sedimentary organic matter. Organic carbon contents reached 1.5% in the Pleistocene samples but Miocene and Pliocene sediments had an average organic carbon content of less than 0.5%. Organic carbon/sulfur ratios are generally below 2.8, reflecting an intense sulfate reduction in the uppermost sediments which was enhanced by sulfate supply both from sea water and deeper strata. Microscopical examinations indicate that the organic matter is mainly derived from marine sources. A small amount of terrigenous organic matter is, however, present as well according to n-alkane and fatty acid distributions. The alkenone unsaturation index U₃₇^k′ shows only a slight decrease during the Miocene and Pliocene, and stronger variations in the Pleistocene, probably indicating more stable sea surface temperatures during the Miocene and Pliocene. Variations in the Pleistocene can possibly be related to glacial/interglacial changes.  相似文献   

Sustainability aspects of thermal water production in the region of Hajdúszoboszló-Debrecen,Hungary     

Tamás Buday  Péter Szűcs  Miklós Kozák  Zoltán Püspöki  Richard William McIntosh  Erika Bódi  Béla Bálint  Kornél Bulátkó 《Environmental Earth Sciences》2015,74(12):7511-7521

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Gravity analysis of salt structures. An example from the El Kef‐Ouargha region (northern Tunisia)     

Mohamed Arfaoui  Mohamed Hdi Inoubli  Saïd Tlig  Rabeh Alouani 《Geophysical Prospecting》2011,59(3):576-591

Triassic outcrops in the Atlassic zone of northern Tunisia may be modelled in two ways: salt bodies piercing through Cretaceous terrains or Triassic salt flows stratified within an Albian series. Both models find support from gravity data and are debatable. To evaluate the mass distribution changes with depth, the Bouguer anomaly of the El Kef‐Ouargha region was successively decomposed into regional and residual components to construct multiple pseudo‐depth slices and apparent density maps. Analyses of gravity lows clearly show a vertical continuity of less dense materials below the Triassic salt outcrops. These features can be explained by salt diapirism during Mesozoic and Cenozoic. Further, gravity data tend to indicate less dense materials below Aptian outcropping in Jebel Aite (Oued Bou Adila); thus suggesting Triassic materials occurring at depth. In addition, dense entities were recognized under Mio‐Pliocene and Quaternary deposits, which are thought to correspond to Cretaceous paleoshoals currently collapsed by non‐outcropping faults. Our findings lend support to a diapir model intruding overburden rather than the salt glacier model stratified in the Albian series proposed by some authors as the genetic structural model for Triassic material‐bearing series in the north of Tunisia.  相似文献   

Seasonal fluctuations and mobility of arsenic in groundwater resources, Anchorage, Alaska     

LeeAnn Munk  Birgit HagedornDerek Sjostrom 《Applied Geochemistry》2011,26(11):1811-1817

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Vegetation history reconstructed from anthracology and pollen analysis at the rescue excavation of the MO Motorway, Hungary     

Katalin Náfrádi  Elvira Bodor  Tünde Törőcsik  Pál Sümegi 《Central European Journal of Geosciences》2011,3(4):358-367

The significance of geoarchaeological investigations is indisputable in reconstructing the former environment and in studying the relationship between humans and their surroundings. Several disciplines have developed during the last few decades to give insight into earlier time periods and their climatic conditions (e.g. palynology, malacology, archaeobotany, phytology and animal osteology). Charcoal and pollen analytical studies from the rescue excavation of the MO motorway provide information about the vegetation changes of the past. These methods are used to reconstruct the environment of the former settlements and to detect the human impact and natural climatic changes. The sites examined span the periods of the Late-Copper Age, Late-Bronze Age, Middle-Iron Age, Late-Iron Age, Sarmatian period, Late Sarmatian period, Migration period, Late-Migration period and Middle Ages. The vegetation before the Copper Age is based only on pollen analytical data. Anthracological results show the overall dominance of Quercus and a great number of Ulmus, Fraxinus, Acer, Fagus, Alnus and Populus/Salix tree fossils, as well as the residues of fruit trees present in the charred wood assemblage.  相似文献   

The VLTI – A Status Report     

A. Glindemann  J. Algomedo  R. Amestica  P. Ballester  B. Bauvir  E. Bugueño  S. Correia  F. Delgado  F. Delplancke  F. Derie  Ph. Duhoux  E. di Folco  A. Gennai  B. Gilli  P. Giordano  Ph. Gitton  S. Guisard  N. Housen  A. Huxley  P. Kervella  M. Kiekebusch  B. Koehler  S. Lévêque  A. Longinotti  S. Ménardi  S. Morel  F. Paresce  T. Phan Duc  A. Richichi  M. Schöller  M. Tarenghi  A. Wallander  M. Wittkowski  R. Wilhelm 《Astrophysics and Space Science》2003,286(1-2):35-44

The Very Large Telescope (VLT) Observatory on Cerro Paranal (2635 m) in Northern Chile is approaching completion. After the four 8-m Unit Telescopes (UT) individually saw first light in the last years, two of them were combined for the first time on October 30, 2001 to form a stellar interferometer, the VLT Interferometer. The combination in pairs of all four UTs was completed in September 2002. In this article, we will describe the subsystems of the VLTI and the planning for the following years. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Jet–gas interactions in z∼ 2.5 radio galaxies: evolution of the ultraviolet line and continuum emission with radio morphology     

A. Humphrey  M. Villar-Martín  R. Fosbury  J. Vernet  S. di Serego Alighieri 《Monthly notices of the Royal Astronomical Society》2006,369(3):1103-1114

We present an investigation into the nature of the jet–gas interactions in a sample of 10 radio galaxies at  2.3 < z < 2.9  using deep spectroscopy of the ultraviolet (UV) line and continuum emission obtained at Keck II and the Very Large Telescope. Kinematically perturbed gas, which we have shown to be within the radio structure in previous publications, is always blueshifted with respect to the kinematically quiescent gas, is usually spatially extended, and is usually detected on both sides of the nucleus. In the three objects from this sample for which we are able to measure line ratios for both the perturbed and quiescent gases, we suggest that the former has a lower ionization state than the latter.
We propose that the perturbed gas is part of a jet-induced outflow, with dust obscuring the outflowing gas that lies on the far side of the object. The spatial extent of the blueshifted perturbed gas, typically ∼35 kpc, implies that the dust is spatially extended at least on similar spatial scales.
We also find interesting interrelationships between UV line, UV continuum and radio continuum properties of this sample.  相似文献   

Dry granular masses impacting on rigid obstacles: numerical analysis and theoretical modelling     

Redaelli  Irene  di Prisco  Claudio  Calvetti  Francesco 《Acta Geotechnica》2021,16(12):3923-3946

Acta Geotechnica - The assessment of the time evolution of the impact force exerted by dry flowing masses on rigid obstacles is mandatory for the dynamic design of sheltering structures and the...  相似文献   

Experimental investigation of the time-dependent response of unreinforced and reinforced tunnel faces in cohesive soils     

Claudio di Prisco  Luca Flessati  Gabriele Frigerio  Riccardo Castellanza  Marco Caruso  Andrea Galli  Pietro Lunardi 《Acta Geotechnica》2018,13(3):651-670

In spite of the increasing diffusion of tunnel boring machines, conventional tunnelling is still preferred for economic reasons in case of short tunnels, unconventional cross sections or irregular tunnel trajectories. In conventional tunnelling, the mechanical response of the tunnel front is a main concern and, when tunnels are excavated in cohesive soils, this is dominated by the time factor, related to geometry, to the mean excavation rate and to the hydro-mechanical properties of the materials involved. This is particularly evident during excavation standstill: front displacements progressively increase with time and, in many cases, the system response under long-term conditions becomes unstable. In conventional tunnelling, a common technique employed to improve the system response (under both short- and long-term conditions) is the installation of fibreglass tubes within the advance core. In this paper, the mechanical response of both unreinforced and reinforced deep tunnel fronts in cohesive soils is experimentally analysed. In particular, the results of a series of 1 g small-scale tests, taking into account both the influence of the excavation rate (the unloading time) on the system response and the evolution with time of the tunnel face displacements, induced by a rapid reduction in the horizontal stress applied on the tunnel face, are reported.  相似文献