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51.
Veronica Della Dora 《Geographical review》2015,105(2):251-255
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Daniela Veronica Ghica 《Journal of Seismology》2011,15(3):487-506
Data recorded with the Bucovina Romanian Seismic Array (BURAR) seismic array between January 2005 and December 2008 were analyzed
to verify the monitoring capabilities of regional and distant seismicity. For this time interval, nearly 35,000 events detected
by BURAR and identified in seismic bulletins (Preliminary Determination of Epicenters and Romanian Earthquake Catalogue) were
investigated using parameters as backazimuth, epicentral distance and magnitude. A remarkably detection capability is emphasized
for teleseismic observations (Δ > 20°). BURAR onsets could be associated to almost 60% of all events in the teleseismic distance,
with a magnitude detection threshold of 4.5 (mb). When no threshold magnitude is applied, the full detection capability of
BURAR is in the same order as the performance of GERES array, which is one of the most sensitive stations in Central Europe.
For regional events, detection capability decreases to about 16% of all events within regional distance range. The site conditions
(crustal structure and high frequency cultural noise) as well as array dimension, affect the signal coherency and reduce the
array detection capability for regional events. For both teleseismic and regional distances, a monthly variation of BURAR
detection capabilities has been found; the number of events detected during the summer time is diminished by the specific
seasonal human activity and atmospheric conditions (thunderstorms). To prove the good detection capability of the BURAR for
teleseismic distances, a comparison with the observations of the Romanian Real Time Network in terms of magnitude and epicentral
distance was carried out. The higher signal detection capability of BURAR is due to the array techniques applied in data processing,
which enhance the signal-to-noise ratio. The monitoring performed by the BURAR seismic array provides a good azimuthal coverage
of the regional and distant seismicity, in a large range of epicentral distances. 相似文献
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Veronica Rossi Giulia Barbieri Stefano Claudio Vaiani Marco Cacciari Luigi Bruno Bruno Campo Marco Marchesini Silvia Marvelli Alessandro Amorosi 《第四纪科学杂志》2021,36(6):961-979
Framed into a robust stratigraphic context, multivariate analyses on the Holocene palaeobiological record (pollen, benthic foraminifers, ostracods) of the Po coastal plain (NE Italy) allowed the investigation of microtidal ecosystems variability and driving parameters along a 35-km-long land–sea transect. Millennial-scale ecosystem shifts are documented by coeval changes in the meiofauna, reflecting variations in organic matter–water depth (shallow-marine environments) and degree of confinement-salinity (back-barrier settings). In-phase shifts of vegetation communities track unsteady water-table levels and river dynamics in freshwater palustrine areas. Five environmental–ecological stages followed one another crossing four tipping points that mark changes in relative sea level (RSL), climate and/or fluvial regime. At the culmination of Mediterranean RSL rise, after the 8200 event, remarkable growth of peatlands took place in the Po estuary, while low accumulation rates typified the shelf. At the transgressive–regressive turnaround (~7000 cal a bp ), the estuary turned into a delta plain with tidally influenced interdistributary embayments. River flow regime oscillations after the Climate Optimum (post-5000 cal a bp ) favoured isolation of the bays and the development of brackish wetlands surrounded by wooded peatlands. The youngest threshold (~800 cal a bp ), which led to the establishment of the modern delta, reflects a major avulsion of the Po River. 相似文献
54.
Rates of pelagic nitrification, measured using N-Serve-sensitive [14C]bicarbonate uptake, varied by as much as an order-of-magnitude among three sites along the salinity gradient of Narragansett Bay (Rhode Island, United States). Rates were always higher at the Providence River estuary site (0.04–11.2 μmol N I?1 d?1) than at either the lower Narragansett Bay site (0.02–0.98 μmol N I?1d?1) or the freshwater Blackstone River site (0.04–1.7 μmol N I?1d?1). Although temperature was the most important variable regulating the annual cycle of nitrification, ammonium concentrations were most likely responsible for the large differences in rates among the three sites in summer. At the levels found in this estuarine system, salinity and concentrations of oxygen or total suspended matter did not appear to have a direct measurable effect on nitrification and pH did only occasionally. Nitrification played an important role in the nitrogen cycle at all three sites. In Narragansett Bay, nitrification contributed 55% of the NO2 ? and NO3 ? entering annually, and was the major source during spring and summer. Water from offshore was the only other large source of NO2 ? and NO3 ?, contributing 34%. High summer rates of nitrification could support much of the phytoplankton uptake of NO2 ? and NO3 ?. In the Providence River estuary, the largest annual input of NO2 ? and NO3 ? was from rivers (54%), although nitrification (28%) and water from lower portions of the bay (11%) also made large contributions. Again, nitrification was most important in the summer. The high rates of nitrification in the Providence River estuary during summer were also likely to be important in terms of oxygen demand, and the production of nitric and nitrous oxides. In the Blackstone River, NO2 ? and NO3 ? concentrations increased as the river flowed through Rhode Island, and nitrification was a possible source. 相似文献
55.
Distribution and seasonal variation of concentrations of particulate carbohydrates and uronic acids in the northern Indian Ocean 总被引:3,自引:0,他引:3
Vishwas B. Khodse Loreta Fernandes V.V. Gopalkrishna Narayan B. Bhosle Veronica Fernandes S.G. Prabhu Matondkar Ravi Bhushan 《Marine Chemistry》2007,103(3-4):327-346
Suspended particulate matter (SPM) samples were collected from the surface seawaters at 31 stations, and from various depths (2 to 1000 m) at 9 locations in the northern Indian Ocean during various seasons. SPM samples were analyzed for total particulate carbohydrate (TPCHO), total particulate uronic acid (TPURA) and total particulate neutral carbohydrate (TPNCHO) concentrations and composition. Strong spatial, temporal and depth related variations were evident in the distribution of these compounds. In surface waters, concentrations of TPCHO, TPNCHO, and TPURA varied from 0.57 to 3.58 μM C, 0.11 to 2.34 μM C, and from 0.01 to 0.31 μM C, respectively, and accounted for 2.6 to 34.6%, 2 to 24.5%, and 0.2 to 6.3% of POC, respectively, whereas the TPURA accounted for 4.7 to 22.7% of TPCHO. Concentrations and yields of both TPNCHO and TPURA decreased rapidly in the upper 100 m of the water column suggesting their utilization by heterotrophic organisms. Glucose was the most abundant constituent of the TPNCHO. Glucose mole fraction decreased while that of other monosaccharides, especially galactose, arabinose, mannose, rhamnose and fucose increased in the upper 100 m water. Below this depth, mole fraction of glucose increased while that of other sugars decreased with the increasing water depth. Generally, high C:N ratios were associated with low yields of carbohydrates and uronic acids. Inverse correlation between the mole fractions of arabinose plus xylose and rhamnose plus fucose indicates the importance of biogenic and terrestrial organic matter input to the Bay of Bengal. TPURA are surface-active in nature and thus may play an important role in coagulation of particles and macromolecules. The observed spatial and seasonal variations of these compounds may be due to differences in phytoplankton biomass, nutrient status, and the influence of terrestrial material. 相似文献
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57.
Andrew O. Langford Veronica M. Bierbaum Stephen R. Leone 《Planetary and Space Science》1985,33(10):1225-1228
Recent flowing afterglow measurements have shown that the reaction of N+ with O2 produces 70 ± 30% of the oxygen atom product as and < 0.1% as . These results indicate that this reaction does not contribute to the auroral green line emission (5577 Å), but can account for ~10% of the observed red line (6300 Å) auroral emission. 相似文献
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59.
Teresa Salvatici Stefano Morelli Veronica Pazzi William Frodella Riccardo Fanti 《山地科学学报》2017,14(4):636-648
On 4th November 2010, a debris flow detached from a large debris cover accumulated above the lowermost portion of the Rotolon landslide (Vicentine Pre-Alps, NE Italy) and channelized in the valley below within the Rotolon Creek riverbed. Such event evolved into a highly mobile and sudden debris flow, damaging some hydraulic works and putting at high risk four villages located along the creek banks. A monitoring campaign was carried out by means of a ground based radar interferometer (GB-InSAR) to evaluate any residual displacement risk in the affected area and in the undisturbed neighbouring materials. Moreover, starting from the current slope condition, a landslide runout numerical modelling was performed by means of DAN-3D code to assess the impacted areas, flow velocity, and deposit distribution of the simulated events. The rheological parameters necessary for an accurate modelling were obtained through the back analysis of the 2010 debris flow event. Back analysis was calibrated with all of the available terrain data coming from field surveys and ancillary documents, such as topographic, geomorphological and geological maps, with pre- and post-event LiDAR derived DTMs, and with orthophotos. Finally, to identify new possible future debris flow source areas as input data for the new modelling, all the obtained terrain data were reanalysed and integrated with the GB-InSAR displacement maps; consequently, new simulations were made to forecast future events. The results show that the integration of the selected modelling technique with ancillary data and radar displacement maps can be a very useful tool for managing problems related to debris flow events in the examined area. 相似文献