Numerical Investigation of the Impact of Ethanol on Flow in the Vadose Zone     

Sciortino Antonella  Feike J. Leij 《Ground water》2012,50(6):883-894

There is a need to elucidate the impact of ethanol on the subsurface environment because of the application of ethanol as automotive fuel. This study quantifies the effects of changes in surface tension, viscosity, and density induced by ethanol on the transmission and retention of water in the vadose zone. The HYDRUS‐1D model was modified to simulate two different scenarios of flow in a sandy loam involving ponding (constant head) or spillage with a subsequent rainfall event (constant flux). Solutions containing different amounts of the highly miscible ethanol (10, 50, and 100% by weight) as well as pristine water were considered. During ponding, ethanol reduced the amount of fluid entering the soil and slowed down the advancement of the wetting front. Viscosity effects were predominant for this scenario, reducing the average depth of the infiltrating liquid up to 44%. The total amount of pure ethanol that entered the soil was 11.38 vs. 17.64 cm for pure water. For the spillage scenario, the results suggest that density has little impact on the liquid movement. Surface tension effects are predominant in the upper portion of the soil. The changes in hydraulic conductivity due to ethanol‐induced modifications of solution viscosity are responsible for the slower advancement of the moisture front. The 10% ethanol solution moved 43.1% faster than pure ethanol during the first 2 d because of viscosity and surface tension effects.  相似文献   

Sedimentary diatoms along a temporal and spatial gradient of metal contamination     

Antonella Cattaneo  Yves Couillard  Sybille Wunsam 《Journal of Paleolimnology》2008,40(1):115-127

We examined changes at the community and population level of sedimentary diatoms over a wide temporal and spatial gradient of metal pollution encountered in cores from three lakes in the Abitibi mining region (Québec, Canada). Diatom communities on the whole appeared to be very tolerant of metal contamination, as shown by diatom cell accumulation rates decreasing only under the most severe conditions of contamination, which were found from the 1930s to the 1980s in Lac Dufault (cadmium, up to 94 μg/g dry sediment; Cu, up to 8600 μg/g; Zn, up to 9000 μg/g). Under the moderate conditions of contamination observed in the other two lakes and in the most recent sediment of Lac Dufault, diatom cell accumulation rates tended to increase over values typical of the pre-mining period. However, there were increasing rearrangements of the community composition along the contamination gradient. Under moderate metal enrichment, the diatom community of Lac Vaudray experienced only subtle changes, with Cyclotella stelligera, albeit decreasing, remaining the dominant taxon. In the intermediately contaminated Lac Caron, several benthic taxa, noticeably Cymbella silesiaca and several Fragilaria species, rose in taxonomic importance. The most extreme contamination observed in Lac Dufault led to a severely impoverished community almost entirely represented by Achnanthes minutissima and Brachysira vitrea. With increasing levels of contamination, there was a shift from planktonic to benthic taxa and morphotypes and a consistent decrease in the siliceous stomatocysts/diatom frustules ratio. These trends suggest that littoral zones may represent an important refugium under conditions of high contamination. Responses to metal stress were in general more evident at the population than at the community level. Cyclotella stelligera and B. vitrea had a consistent negative and positive response, respectively, along the gradient and are the most promising indicators of metal pollution for this region.  相似文献   

Messinian deposits and erosion in northern Tunisia: inferences on Strait of Sicily during the Messinian Salinity Crisis     

Narjess El Euch-El Koundi  Serge Ferry  Jean-Pierre Suc  Georges Clauzon  Mihaela Carmen Melinte-Dobrinescu  Christian Gorini  Anissa Safra  Fouad Zargouni 《地学学报》2009,21(1):41-48

Outcrops, offshore wells, electric logs and seismic profiles from northern Tunisia provide an opportunity to decipher the Messinian Salinity Crisis in the Strait of Sicily. Messinian deposits (including gypsum beds) near the Tellian Range reveal two successive subaerial erosional surfaces overlain by breccias and marine Zanclean clays, respectively. In the Gulf of Tunis, Messinian thick evaporites (mostly halite) are strongly eroded by a fluvial canyon infilled with Zanclean clays. The first erosional phase is referred to the intra-Messinian tectonic phase and is analogous to that found in Sicily. The second phase corresponds to the Messinian Erosional Surface that postdates the marginal evaporites, to which the entire Sicilian evaporitic series must refer. The Western and Eastern Mediterranean basins were separated during deposition of the central evaporites.  相似文献   

Frequency Distributions of Geochemical Data,Scaling Laws,and Properties of Compositions     

Antonella Buccianti 《Pure and Applied Geophysics》2015,172(7):1851-1863

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The ITalian ACcelerometric Archive (ITACA): processing of strong-motion data   总被引：1，自引：1，他引：0  

Marco Massa  Francesca Pacor  Lucia Luzi  Dino Bindi  Giuliano Milana  Fabio Sabetta  Antonella Gorini  Sandro Marcucci 《Bulletin of Earthquake Engineering》2010,8(5):1175-1187

The Italian strong-motion database was created during a joint project between Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italian Institute for Geophysics and Vulcanology) and Dipartimento della Protezione Civile (DPC, Italian Civil Protection). The aim of the project was the collection, homogenization and distribution of strong motion data acquired in Italy in the period 1972–2004 by different institutions, namely Ente Nazionale per l’Energia Elettrica (ENEL, Italian electricity company), Ente per le Nuove tecnologie, l’Energia e l’Ambiente (ENEA, Italian energy and environment organization) and DPC. Recently the strong-motion data relative to the 23th December 2009, Parma (Mw = 5.4 and Mw = 4.9) and to the April 2009 L’Aquila sequences (13 earthquakes with 4.1 ≤ Mw ≤ 6.3) were included in the Italian Accelerometric Archive (ITACA) database (beta release). The database contains 7,038 waveforms from analog and digital instruments, generated by 1.019 earthquakes with magnitude up to 6.9 and can be accessed on-line at the web site . The strong motion data are provided in the unprocessed and processed versions. This article describes the steps followed to process the acceleration time series recorded by analogue and digital instruments. The procedures implemented involve: baseline removal, instrumental correction, band pass filtering with acausal filters, integration of the corrected acceleration in order to obtain velocity and displacement waveforms, computation of acceleration response spectra and strong motion parameters. This procedure is applied to each accelerogram and it is realised to preserve the low frequency content of the records.  相似文献   

E–W opening of the Algerian Basin (Western Mediterranean)     

A. Mauffret  D. Frizon de Lamotte  S. Lallemant  C. Gorini  A. Maillard 《地学学报》2004,16(5):257-264

We present geophysical and geological evidence of fast (2 cm yr^?1 in the east and 5 cm yr^?1 in the west) E–W spreading between 16 and 8 Ma in the region behind the Gibraltar Arc in the Algerian Basin.  相似文献   

On the relations between theoretical and observed colours in theBVRI system     

Filippina Caputo  Antonella Natta 《Astrophysics and Space Science》1973,21(1):73-77

Transformation relations from theoretical apparent magnitude and (b-v), (v-r), (v-i) colurs to the observedm _v and (B-V), (V-R), (V-I) quantities are derived.Black body colours in theBVRI system are also computed.  相似文献   

Paleoecological evidence for diatom response to metal pollution in Lake Orta (N. Italy)     

Delio Ruggiu  Antonella Luglié  Antonella Cattaneo  Pierisa Panzani 《Journal of Paleolimnology》1998,20(4):333-345

Diatom remains were analysed in two short sediment cores from a subalpine Italian lake (Lake Orta), known for its major industrial pollution dating from the late 1920s, which has only recently been stopped. Copper was recognised as the main toxic agent for diatoms during the first 30 years of pollution (peak value: 100 g l-1 in the late 1950s). A diatom community similar to other deep subalpine lakes existed in the past, and was disrupted by the pollution events. Acute and long-term effects of Cu contamination were tracked by changes in three distinct groups of species around the sharp boundary corresponding to the onset of the pollution. These groups were respectively composed of: (1) Species quickly extirpated by the discharge, mostly belonging to Fragilaria and Cyclotella and never reappearing; (2) Species apparently not affected, or not immediately affected, by the pollution, showing no definite trends with time. Synedra species, with various deformities, were conspicuous among these; (3) Species with accumulation rates increasing with time irrespective of pollution, mostly belonging to Achnanthes. Properties and tolerances of these groups (e.g. Synedra and Achnanthes) are discussed in detail.  相似文献   

Three Decades of Seismic Activity at Mt. Vesuvius: 1972–2000     

Giuseppe De?Natale  Igor?Kuznetzov  Tatiana?Kronrod  Antonella?PeresanEmail author  Angela?Saraò  Claudia?Troise  Giuliano F.?Panza 《Pure and Applied Geophysics》2004,161(1):123-144

We analyse the seismic catalogue of the local earthquakes which occurred at Somma-Vesuvius volcano in the past three decades (1972–2000). The seismicity in this period can be described as composed of a background level, characterised by a low and rather uniform rate of energy release and by sporadic periods of increased seismic activity. Such relatively intense seismicity periods are characterised by energy rates and magnitudes progressively increasing in the critical periods. The analysis of the b value in the whole period evidences a well-defined pattern, with values of b progressively decreasing, from about 1.8 at the beginning of the considered period, to about 1.0 at present. This steady variation indicates an increasing dynamics in the volcanic system. Within this general trend it is possible to identify a substructure in the time sequence of the seismic events, formed by the alternating episodes of quiescence and activity. The analysis of the source moment tensor of the largest earthquakes shows that the processes at the seismic source are generally not consistent with simple double-couples, but that they are compatible with isotropic components, mostly indicating volumetric expansion. These components are shown to be statistically significant for most of the analysed events. Such focal mechanisms can be interpreted as the effect of explosion phenomena, possibly related to volatile exsolution from the crystallising magma. The availability of a reduced amount of high quality data necessary for the inversion of the source moment tensor, the still limited period of systematic observation of Vesuvius micro-earthquakes and, above all, the absence of eruptive events during such interval of time, cannot obviously permit the outlining of any formal premonitory signal. Nevertheless, the analysis reported in this paper indicates a progressively evolving dynamics, characterised by a generally increasing trend in the seismic activity in the volcanic system and by a significant volumetric component of recent major events, thus posing serious concern for a future evolution towards eruptive activity.  相似文献   

Vulnerability to renal,heat and respiratory hospitalizations during extreme heat among U.S. elderly   总被引：1，自引：0，他引：1  

Carina J. Gronlund  Antonella Zanobetti  Gregory A. Wellenius  Joel D. Schwartz  Marie S. O’Neill 《Climatic change》2016,136(3-4):631-645

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