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71.
Measurements and Parametrizations of the Atmospheric Boundary-Layer Height at Dome C,Antarctica 总被引:2,自引:2,他引:0
Ilaria Pietroni Stefania Argentini Igor Petenko Roberto Sozzi 《Boundary-Layer Meteorology》2012,143(1):189-206
An experimental campaign, Study of the Atmospheric Boundary Layer Environmental at Dome C, was held during 2005 at the French-Italian
station of Concordia at Dome C. Ground-based remote sensors, as well as in situ instrumentation, were used during the experimental
campaign. The measurements allowed the direct estimation of the polar atmospheric boundary-layer height and the test of several
parametrizations for the unstable and stable boundary layers. During the months of January and February, weak convection was
observed while, during the polar night, a long-lived stable boundary layer occurred continuously. Under unstable stratification
the mixing-layer height was determined using the sodar backscattered echoes and potential temperature profiles. The two estimations
are highly correlated, with the mixing height ranging between 30 and 350 m. A simple prognostic one-dimensional model was
used to estimate the convective mixing-layer height, with the correlation coefficient between observations and model results
being 0.66. The boundary-layer height under stable conditions was estimated from radiosounding profiles as the height where
the critical Richardson number is reached; values between 10 and 150 m were found. A visual inspection of potential temperature
profiles was also used as further confirmation of the experimental height; the results of the two methods are in good agreement.
Six parametrizations from the literature for the stable boundary-layer height were tested. Only the parametrization that considers
the long-lived stable boundary layer and takes into account the interaction of the stable layer with the free atmosphere is
in agreement with the observations. 相似文献
72.
Marie-Emilie Clémence Silvia Gardin Annachiara Bartolini Guillaume Paris Valérie Beaumont Jean Guex 《Swiss Journal of Geoscience》2010,103(2):293-315
A high-resolution micropalaeontological study, combined with geochemical and sedimentological analyses was performed on the
Tiefengraben, Schlossgraben and Eiberg sections (Austrian Alps) in order to characterize sea-surface carbonate production
during the end-Triassic crisis. At the end-Rhaetian, the dominant calcareous nannofossil Prinsiosphaera triassica shows a decrease in abundance and size and this is correlated with a increase in δ18O and a gradual decline in δ13Ccarb values. Simultaneously, benthic foraminiferal assemblages show a decrease in diversity and abundance of calcareous taxa and
a dominance of infaunal agglutinated taxa. The smaller size of calcareous nannofossils disturbed the vertical export balance
of the biological carbon pump towards the sea-bottom, resulting in changes in feeding strategies within the benthic foraminiferal
assemblages from deposit feeders to detritus feeders and bacterial scavengers. These micropalaeontological data combined with
geochemical proxies suggest that changes in seawater chemistry and/or cooling episodes might have occurred in the latest Triassic,
leading to a marked decrease of carbonate production. This in turn culminated in the quasi-absence of calcareous nannofossils
and benthic foraminifers in the latest Triassic. The aftermath (latest Triassic earliest Jurassic) was characterised by abundance
peaks of “disaster” epifaunal agglutinated foraminifera Trochammina on the sea-floor. Central Atlantic Magmatic Province (CAMP) paroxysmal activity, superimposed on a major worldwide regressive
phase, is assumed to be responsible for a deterioration in marine palaeoenvironments. CAMP sulfuric emissions might have been
the trigger for cooling episodes and seawater acidification leading to disturbance of the surface carbonate production at
the very end-Triassic. 相似文献
73.
Regoli F Pellegrini D Winston GW Gorbi S Giuliani S Virno-Lamberti C Bompadre S 《Marine pollution bulletin》2002,44(9):912-922
In the period 1997-2000, approximately 1,800,000 m3 of material dredged from the Port of Leghorn was discharged into a sea dumping site located 14 miles from the coast. The red mullet (Mullus barbatus) was used as a bioindicator species for monitoring the biological impact of these discharges on a geographical and temporal scale. Organisms were sampled over three years (1998-2000) at different stations and several biomarkers, both of exposure and effect, were analyzed. Bioavailability of specific classes of pollutants was evaluated by analyzing levels of metallothioneins, the activity of cytochrome P450 1A (CYPIA) and of glutathione S-transferases. Among biomarkers of effect, special attention was paid to the balance between prooxidant challenge and antioxidant defenses, and to the appearance of damage caused by oxidative stress. The analyses of the main components of the antioxidant system included superoxide dismutase, catalase, glutathione peroxidases, glutathione reductase, glyoxalase I and II, and total glutathione. These data were integrated with the measurement of total oxyradical scavenging capacity (TOSC) as an indication of the overall biological resistance to toxicity of different forms of oxyradicals (peroxyl radicals, hydroxyl radicals and peroxynitrite). Results indicated a biological impact in organisms sampled near the disposal site; the impact was particularly evident during 1999 and mainly related to organic chemicals such as PAH. Exposure to these pollutants also caused variations in the levels and activity of several antioxidants. The analysis of TOSC, however, revealed that the overall capacity of specific tissues of organisms to absorb various oxidants was not seriously compromised when challenged with increased prooxidant pressures. Variations of single antioxidants were useful in revealing early warning "biological responses", while integration with TOSC analyses indicated if such changes also reflect a more integrated and functional "biological effect" with possible consequences at the organisms level. The red mullet appears to be a useful sentinel species for a biomarker approach to monitoring impact caused by dredged materials. 相似文献
74.
75.
Historical maps are effective sources of geographical information and useful for historical and territorial research. In this study, the examination of landscape dynamics on the basis of historical maps over a period of more than 200 years was conducted. The study area is Sorrento peninsula and part of the near Sarno river basin in South Italy. This study provides a general framework for the assessment of the overall quality and accuracy of historical maps. The application of the methodology used in this specific case study can contribute to a better understanding of the dynamics of the landscape in the long term. The derived knowledge can be applied in the planning of the landscape in order to implement correct conservation strategies. The comparison was made on four maps 1817, 1875, 1960, and 2006. Geodetic accuracy of the sheet maps of 1817 and 1875 offer a right basis for a macro analysis of land cover dynamics, evaluating conversion from one land cover category to another. Main transformation, identified in the period between 1875 and 1960, was the disappearance of vineyards, which covered 25% of the total study area in 1875. Agricultural areas increased in this period to cover 57% of the total area. 相似文献
76.
Leonardo Casini Matteo Maino Antonio Langone Giacomo Oggiano Stefania Corvò Joan Reche Estrada Montserrat Liesa 《Journal of Metamorphic Geology》2023,41(1):25-57
The Variscan high-grade metamorphic basement of northern Sardinia and southern Corsica record lower Carboniferous anatexis related to post-collisional decompression of the orogen. Migmatites exposed in the Punta Bianca locality (Italy) consist of quartz + biotite + plagioclase + K-feldspar orthogneisses, garnet and cordierite-bearing diatexite and metatexites, derived from metasediments. Field evidence, petrographic observations, ELA-ICP-MS zircon and monazite dating and pseudosection modelling suggest that anatexis was apparently episodic involving two main stages of partial melting. Using pseudosection modelling, we infer that the first stage of partial melting is in the upper amphibolite facies (~0.45 GPa at ~740°C). Cordierite overgrowths replacing sillimanite, combined with the composition of plagioclase and K-feldspar, suggest decompression followed cooling below the solidus at low pressures of ~0.3 GPa. The age of the first anatectic event is not precisely constrained because of extensive resetting of the isotopic systems during the second melting stage, yet few zircons preserve a lower Carboniferous age which is consistent with the regional dataset. This lower Carboniferous migmatitic fabric is offset by a network of pseudotachylyte-bearing faults suggestive of cooling to greenschist facies conditions. Garnet/cordierite-bearing diatexites incorporate fragments of pseudotachylite-bearing orthogneiss and metatexites. Pseudosection modelling indicates nearly isobaric re-heating up to ~750°C, followed by further cooling below the solidus. The inferred P–T path is consistent with decompression and cooling of the Variscan crust through post-collisional extension and collapse of the thickened orogenic crust, followed by nearly isobaric re-heating at low pressures (~0.3 GPa) yielding to a second melting stage under LP-HT conditions. U/Th-Pb monazite ages for diatexite migmatites indicate an upper bound of 310–316 Ma for the second melting stage, suggesting that the second melting stage is coincident with the regional phase of crustal shearing. The cause of the high geothermal gradient required for re-heating during the second melting stage is unknown but likely requires some heat source that was probably related to dissipation of mechanical work within crustal-scale shear zones. According to this interpretation, some upper Carboniferous peraluminous granite precursors of the Corsica–Sardinia Batholith could be the outcome rather than the cause of the late-Variscan high-T metamorphism. 相似文献
77.
Degli Abbati Stefania Morandi Paolo Cattari Serena Spacone Enrico 《Bulletin of Earthquake Engineering》2022,20(4):2187-2217
Bulletin of Earthquake Engineering - This paper presents the comparison of the results of modal and nonlinear analyses carried out on a 2-story masonry building with rigid diaphragms, inspired by... 相似文献
78.
Alberto De Bonis Stefania Febbraro Chiara Germinario Daniela Giampaola Celestino Grifa Vincenza Guarino Alessio Langella Vincenzo Morra 《Geoarchaeology》2016,31(6):437-466
Recent transportation infrastructure works in Naples, Italy, provided important discoveries related to the production of pottery in the Hellenistic workshop area of Piazza Nicola Amore. A minero‐petrographic investigation was conducted on 35 samples belonging to the widespread Campana A ware and production indicators (clayey raw materials, unfired Graeco‐Italic amphorae, kiln wastes, workshop tools). Additional analysis was conducted on black‐glaze and common ware samples for comparison. The analyses reveal compositional and technological homogeneity of Campana A ware. Samples are characterized by low CaO content with evidence of both volcanic and sedimentary components, suggesting that different clay sources were properly mixed to prepare a standard recipe. Production indicators, black‐glaze and common wares, have a composition well consistent with the calcareous clays from the island of Ischia. Leucite‐ and garnet‐bearing temper from the Somma Volcano were used for the preparation of coarse‐grained pastes, unfired Graeco‐Italic amphorae, and clayey raw materials, thus suggesting that they represented the clay sources for amphorae production. Our results reveal new technological and socioeconomic aspects of Hellenistic pottery production in the Bay of Naples, in particular for the Campana A ware, now representing a new reference group: Neapolis. 相似文献
79.
80.
Gil Penha-Lopes Fabrizio Bartolini Samwel Limbu Stefano Cannicci Erik Kristensen Jos Paula 《Marine pollution bulletin》2009,58(11):1694-1703
The effect of different organic-rich sewage concentration (0%, 20% and 60% diluted in seawater) and absence or presence of mangrove trees on the survival, bioturbation activities and burrow morphology of fiddler crabs species was assessed. After 6 months, males of both species always showed higher survival (80%) when compared to females (20%). Crabs inhabiting pristine conditions achieved higher survival (67–87%) than those living in sewage-exposed mesocosms (40–71%). At 60% sewage loading, fiddler crabs processed less sediment (34–46%) during feeding and excavated slightly more sediment (45–80%) than at pristine conditions. While percent volume of the burrow chambers increased (13–66%) at contaminated mesocosms for both vegetation conditions, burrows were shallower (33%) in bare cells loaded with sewage. The results show that fiddler crabs presented moderate mortality levels in these artificial mangrove wetlands, but mainly in sewage impacted cells. However, they still function as ecosystem engineers through bioturbation activities and burrow construction. 相似文献