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91.
Aya Schneider Mor Ruth Yam Cristina Bianchi Martina Kunz-Pirrung Rainer Gersonde Aldo Shemesh 《Quaternary Research》2012,77(2):317-325
The relationships among internally consistent records of summer sea-surface temperature (SSST), winter sea ice (WSI), and diatomaceous stable isotopes were studied across seven terminations over the last 660 ka in sedimentary cores from ODP sites 1093 and 1094. The sequence of events at both sites indicates that SSST and WSI changes led the carbon and nitrogen isotopic changes in three Terminations (TI, TII and TVI) and followed them in the other four Terminations (TIII, TIV, TV and TVII). In both TIII and TIV, the leads and lags between the proxies were related to weak glacial mode, while in TV and TVII they were due to the influence of the mid-Pleistocene transition. We show that the sequence of events is not unique and does not follow the same pattern across terminations, implying that the processes that initiated climate change in the Southern Ocean has varied through time. 相似文献
92.
The Galaxy Evolution Explorer (GALEX) was successfully launched on April 28, 2003. Over the last 7 years, the GALEX mission
has expanded our understanding of the process of star formation and galaxy evolution. GALEX data, consisting of far-UV (1344-1786A)
and near-UV (1771-2831A) imaging over most of the sky, and grism spectroscopy, are available to the entire astronomical community
and to the general public via the Multi-mission Archive at Space Telescope (MAST). The main characteristics and access tools
to the large data archive (16TB) are presented. Groups within the GALEX Science Team, and the MAST archive teams, have undertaken
complementary projects to conduct all-sky searches for time-variable and transient sources within GALEX data (e.g. Welsh et
al. in Astron. J. 130:823, 2005; Wheatley et al. in Astron. J. 136:259, 2008). Results and tools for variability searches developed by MAST during this process, will be made available to the general
community. 相似文献
93.
Nina Keul John W. Morse Rik Wanninkhof Dwight K. Gledhill Thomas S. Bianchi 《Aquatic Geochemistry》2010,16(3):337-351
This paper presents the results of two cruises in the Northern Gulf of Mexico in 2008 that investigated local and short-term
factors influencing the carbonate chemistry dynamics and saturation state with respect to aragonite (Ωaragonite) of surface seawater in this region. One cruise covered much of the northern half of the Gulf, and the other focused on
the coastal zone west of the Atchafalaya Bay outlet of the Mississippi River—the region where the hypoxic “dead zone” occurs
on the Louisiana shelf. Offshore waters (>100 m depth) exhibited only small variations in CO2 fugacity (fCO2), total alkalinity (TA) and Ωaragonite. Values were close to those typically observed in subtropical Atlantic Ocean and Caribbean Sea waters of similar salinity.
However, inner shelf waters (<50 m depth) exhibited large variations in fCO2, TA, and Ωaragonite that were not directly related to salinity or distance from the Mississippi River plume. Changes in TA values were not the
result of simple mixing of end-member freshwater and seawater TA concentrations but exhibited a minimum in values near salinity
of 25. This minimum could be the result of microbial recycling across salinity gradients, biological removal of alkalinity
by formation of calcium carbonate or mixing of a third end-member with a low alkalinity such as Terrebonne Bay. All waters
were supersaturated with respect to aragonite. Offshore waters had an average Ωaragonite of 3.86 with a standard deviation of only ±0.06 and inner shelf waters had a range in Ωaragonite values from 3.9 to 9.7 with a median of 4.3. Shelf water Ωaragonite values were elevated relative to the offshore as a consequence of both high TA input from Mississippi River and biological
drawdown of CO2. A dominant factor controlling Ωaragonite distribution in offshore waters with relatively constant temperatures was fCO2, with higher supersaturation occurring in areas with low fCO2. 相似文献
94.
Stefano Gori Biagio Giaccio Fabrizio Galadini Emanuela Falcucci Paolo Messina Andrea Sposato Francesco Dramis 《International Journal of Earth Sciences》2011,100(1):157-171
In the present work we analyse one of the active normal faults affecting the central Apennines, i.e. the Mt. Morrone normal
fault system. This tectonic structure, which comprises two parallel, NW-SE trending fault segments, is considered as potentially
responsible for earthquakes of magnitude ≥ 6.5 and its last activation probably occurred during the second century AD. Structural
observations performed along the fault planes have allowed to define the mainly normal kinematics of the tectonic structure,
fitting an approximately N 20° trending extensional deformation. Geological and geomorphological investigations performed
along the whole Mt. Morrone south-western slopes permitted us to identify the displacement of alluvial fans, attributed to
Middle and Late Pleistocene by means of tephro-stratigraphic analyses and geomorphological correlations with dated lacustrine
sequences, along the western fault branch. This allowed to evaluate in 0.4 ± 0.07 mm/year the slip rate of this segment. On
the other hand, the lack of synchronous landforms and/or deposits that can be correlated across the eastern fault segment
prevented the definition of the slip rate related to this fault branch. Nevertheless, basing on a critical review of the available
literature dealing with normal fault systems evolution, we hypothesised a total slip rate of the fault system in the range
of 0.4 ± 0.07 to 0.8 ± 0.09 mm/year. Moreover, basing on the length at surface of the Mt. Morrone fault system (i.e. 22–23 km)
we estimated the maximum expected magnitude of an earthquake that might originate along this tectonic structure in the order
of 6.6–6.7. 相似文献
95.
Roberta LasagnaMonica Montefalcone Giancarlo AlbertelliNicola Corradi Marco FerrariCarla Morri Carlo Nike Bianchi 《Estuarine, Coastal and Shelf Science》2011,94(3):255-262
While coastal management activities have long been known to exert a strong influence on the health of marine ecosystems, neither scientists nor administrators have realized that small interventions may lead to disproportionately larger impacts. This study investigated the broad and long-lasting environmental consequences of the construction of an ill-planned, although small (only 12 m long) jetty for pleasure crafts on the hydrodynamic conditions and on the meadow of the seagrass Posidonia oceanica of an embayed cove in the Ligurian Sea (NW Mediterranean). There, P. oceanica used to develop on a high (>1.5 m) matte (a lignified terrace causing seafloor elevation) in which the leaves reach the surface and form a compact natural barrier to waves in front of the beach. Such a so-called ‘fringing reef’ of P. oceanica is today recognized of high ecological value and specific conservation efforts are required. The construction of the jetty implied the cutting of the matte, which directly destroyed part of the fringing reef. In addition, meadow mapping and sedimentological analyses coupled with morphodynamic modelling showed that the ecosystem of the whole cove had been greatly altered by the jetty. We used the geometric planform approach, a proper tool in the study of headland-controlled embayment, both to characterise the present situation of Prelo cove and to simulate the original one, before the jetty was built. In the long term, such a small jetty completely altered the configuration and the hydrodynamic conditions of the whole cove, splitting the original pocket beach into two smaller ones and creating strong rip-currents flowing seaward along the jetty. These rip-currents enhanced erosion of residual shallow portions of the meadow and further modified the sedimentary fluxes in shallow waters. A century after the construction of the jetty, an irreversible environmental damage has occurred, as the slow growing rate of P. oceanica implies that the high matte terrace and the fringing reef will hardly form again, even after the removal of the jetty. The lesson learnt from this study is that even such small, and therefore reputed intrinsically ‘innocent’, interventions on the coastal zone require accurate planning based on interdisciplinary studies to understand and respect the delicate interplay among morphological, hydrodynamic and ecological components. 相似文献
96.
Stefano Bianchi Giorgio Matt Fabrizio Nicastro Delphine Porquet Jacques Dubau 《Monthly notices of the Royal Astronomical Society》2005,357(2):599-607
We have calculated the equivalent widths of the absorption lines produced by Fe xxv and Fe xxvi in a Compton-thin, low-velocity photoionized material illuminated by the nuclear continuum in active galactic nuclei. The results, plotted against the ionization parameter and the column density of the gas, are a complement to those presented by Bianchi & Matt for the emission lines from the same ionic species. As an extension to the work by Bianchi & Matt, we also present a qualitative discussion on the different contributions to the He-like iron emission line complex in the regimes where recombination or resonant scattering dominates, providing a useful diagnostic tool to measure the column density of the gas. Future high-resolution missions (e.g. Astro-E2 ) will allow us to fully take advantage of these plasma diagnostics. In the meantime, we compare our results with an up-to-date list of Compton-thick and unobscured (at least at the iron line energy) Seyfert galaxies with emission and/or absorption lines from H- and He-like iron observed with Chandra and XMM–Newton . 相似文献
97.
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100.
Cristiana Guerranti Stefania Ancora Nicola Bianchi Guido Perra Emiliano Leonida Fanello Simonetta Corsolini Maria Cristina Fossi Silvano Ettore Focardi 《Marine pollution bulletin》2013
Perfluorinated compounds (PFCs), widely used for their hydro-oil repellent properties, are almost non-degradable in the environment; there is scientific evidence that indicate bioaccumulation. They represent a threat to many organisms, because they are toxic and are endocrine disruptors. Scientific studies have demonstrated the presence of PFCs in blood and liver samples of fish, turtles, birds and mammals of marine ecosystems in different geographical areas. The aim of this study was to determine the distribution of PFOS and PFOA in blood samples of the marine turtle Caretta caretta, using a minimally invasive sampling procedure. 49 blood samples of marine turtle, taken from several Italian marine turtle rescue centers, were analyzed. While PFOA was never detected, measurable concentrations of PFOS were found in 15 blood samples; the values show a range from 1.14 ng/g to 28.51 ng/g (wet wt.). No differences between groups of samples taken from different areas were found. 相似文献