Groundwater connections under a barrier beach: A case study in the Venice Lagoon     

John Rapaglia  Eloisa Di Sipio  Henry Bokuniewicz  Gian Maria Zuppi  Luca Zaggia  Antonio Galgaro  Aaron Beck 《Continental Shelf Research》2010

The flow of groundwater beneath barrier islands has been cited as a possible pathway for salt water and chemical exchange between a protected embayment and the open sea. Evidence is presented that identifies an exchange of groundwater through a highly permeable paleoinlet along the barrier beach of Cavallino, which separates the northern Venice Lagoon from the Adriatic Sea. We utilized both point measurements of submarine groundwater discharge (SGD) and a geophysical investigation of the subsurface resistivity to analyze the movement of saline groundwater. Discharge of groundwater and associated nutrients, was higher at the site of a former inlet than at a similar site along the barrier and modulated by the difference in tidal water level between the lagoon and Adriatic Sea. If the measured conditions are typical, storm surge barriers could potentially result in a saline groundwater flow of up to 1.5×10⁶ m³ d⁻¹ into the lagoon.  相似文献   

From regional- to local-scale seismic hazard assessment: examples from Southern Spain     

Jorge M. Gaspar-Escribano  Manuel Navarro  Belén Benito  Antonio García-Jerez  Francisco Vidal 《Bulletin of Earthquake Engineering》2010,8(6):1547-1567

An approach that relates results from a regional seismic hazard assessment study with local-scale site-effect characterizations in an area of low-to-moderate seismic activity such as Andalusia (southern Spain), is presented. Results of a previous probabilistic seismic hazard analysis of Andalusia on rock conditions are disaggregated to infer hazard controlling earthquakes for different target motions. A collection of controlling magnitude-distance pairs and the corresponding site-specific response spectra at main capital cities of the region are obtained. These spectra are first-order approximations to expected seismic actions required in local earthquake risk assessments. In addition, results of independent, local-scale studies developed in Almeria City (SE Andalusia) are used to derive an updated seismic zonation of the city. These include predominant soil period estimates and shear-wave velocity profiles at different locations. If a local seismic risk assessment study or an earthquake-resistant structural design is to be developed, it may be recommended the use of different seismic actions on sites characterized by distinct response to seismic shaking (as derived from the seismic zonation). The seismic action related to worst-case scenarios may be modeled through a hazard-consistent response spectrum, obtained by hazard disaggregation at the spectral acceleration with period matching the prevailing resonant period of the target site or structure.  相似文献   

Use of Chitosan with Different Deacetylation Degrees for the Adsorption of Food Dyes in a Binary System          下载免费PDF全文

Janaína O. Gonçalves  Diana A. Duarte  Guilherme L. Dotto  Luiz Antonio A. Pinto 《洁净——土壤、空气、水》2014,42(6):767-774

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Representivity of incompletely sampled fall deposits in estimating eruption source parameters: a test using the 12–13 January 2011 lava fountain deposit from Mt. Etna volcano,Italy     

Daniele Andronico  Simona Scollo  Antonio Cristaldi  Maria Deborah Lo Castro 《Bulletin of Volcanology》2014,76(10):1-14

The Southeast Crater (SEC) of Mt. Etna, Italy, is renowned for its high activity, mainly long-lived eruptions consisting of sequences of individual paroxysmal episodes which have produced more than 150 eruptive events since 1998. Each episode typically forms eruption columns followed by tephra fallout over distances of up to about 100 km from the vent. One of the last sequences consisted of 25 lava fountaining events, which took place between January 2011 and April 2012 from a pit-vent on the eastern flank of the SEC and built a new scoria cone renamed New Southeast Crater. The first episode on 12–13 January 2011 produced tephra fallout which was unusually dispersed toward to the South extending out over the Mediterranean Sea. The southerly deposition of tephra permitted an extensive survey at distances between ~1 and ~100 km, providing an excellent characterization of the tephra deposit. Here, we document the stratigraphy of the 12–13 January fallout deposit, draw its dispersal, and reconstruct its isopleth map. These data are then used to estimate the main eruption source parameters. The total erupted mass (TEM) was calculated by using four different methodologies which give a mean value of 1.5?±?0.4?×?10⁸ kg. The mass eruption rate (MER) is 2.5?±?0.7?×?10⁴ kg/s using eruption duration of 100 min. The total grain-size (TGS) distribution, peaked at ?3 phi, ranges between ?5 and 5 phi and has a median value of ?1.4 phi. Further, for the eruption column height, we obtained respective values of 6.8–13.8 km by using the method of Carey and Sparks (1986) and 3.4?±?0.3 km by using the methods of Wilson and Walker (1987), Mastin et al. (2009), and Pistolesi et al. (2011) and considering the mean value of MER from the deposit. We also evaluated the uncertainty and reliability of TEM and TGS for scenarios where the proximal and distal samples are not obtainable. This is achieved by only using a sector spanning the downwind distances between 6 and 23 km. This scenario is typical for Etna when the tephra plume is dispersed eastward, i.e., in the prevailing wind direction. Our results show that, if the analyzed deposit has poorer sample coverage than presented in this study, the TEM (3.4?×?10⁷ kg) is 22 % than the TEM obtained from the whole deposit. The lack of the proximal (<6 km) deposit may cause more significant differences in the TGS estimations.  相似文献   

The state of water resources in major Mediterranean islands     

Francesco Viola  Manuel Sapiano  Michael Schembri  Clive Brincat  Antonio Lopez  Attilio Toscano  Evan Diamadopoulos  Bambos Charalambous  Bruno Molle  Michael Zoumadakis  Antonina Torrens Armengol  Margarita Gallinas Vich  Maria Teresa Noto 《Water Resources》2014,41(6):639-648

This work analyses the state of water resources in six Mediterranean islands: Corsica, Crete, Cyprus, Mallorca, Malta and Sicily. The analysis is focused on the prevailing social, economic and hydroclimatological characteristics of these islands in order to identify the main common features affecting water availability, demand and use. A detailed analysis of the state of water resources in all the considered islands has been carried out. A background of current conditions relating to freshwater availability, quality and use has been established. Different strategies to face water scarcity and enhance water quality in theislands have been assessed in a context of climate change which is a common threat. The identification of similar problems for all the islands highlights the importance of strengthening inter-islands co-operation in the field of sustainable water resources management.  相似文献   

Spatial and environmental analysis of an ostracod metacommunity from endorheic lakes     

Andreu Castillo-Escrivà  Luis Valls  Carlos Rochera  Antonio Camacho  Francesc Mesquita-Joanes 《Aquatic Sciences - Research Across Boundaries》2016,78(4):707-716

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Monitoring crater-wall collapse at active volcanoes: a study of the 12 January 2013 event at Stromboli     

Sonia Calvari  Emanuele Intrieri  Federico Di Traglia  Alessandro Bonaccorso  Nicola Casagli  Antonio Cristaldi 《Bulletin of Volcanology》2016,78(5):39

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Reconstructing eruptive source parameters from tephra deposit: a numerical study of medium-sized explosive eruptions at Etna volcano     

Antonio Spanu  Mattia de’ Michieli Vitturi  Sara Barsotti 《Bulletin of Volcanology》2016,78(9):59

Since the 1970s, multiple reconstruction techniques have been proposed and are currently used, to extrapolate and quantify eruptive parameters from sampled tephra fall deposit datasets. Atmospheric transport and deposition processes strongly control the spatial distribution of tephra deposit; therefore, a large uncertainty affects mass derived estimations especially for fall layer that are not well exposed. This paper has two main aims: the first is to analyse the sensitivity to the deposit sampling strategy of reconstruction techniques. The second is to assess whether there are differences between the modelled values for emitted mass and grainsize, versus values estimated from the deposits. We find significant differences and propose a new correction strategy. A numerical approach is demonstrated by simulating with a dispersal code a mild explosive event occurring at Mt. Etna on 24 November 2006. Eruptive parameters are reconstructed by an inversion information collected after the eruption. A full synthetic deposit is created by integrating the deposited mass computed by the model over the computational domain (i.e., an area of 7.5 × 10⁴ km ²). A statistical analysis based on 2000 sampling tests of 50 sampling points shows a large variability, up to 50 % for all the reconstruction techniques. Moreover, for some test examples Power Law errors are larger than estimated uncertainty. A similar analysis, on simulated grain-size classes, shows how spatial sampling limitations strongly reduce the utility of available information on the total grain size distribution. For example, information on particles coarser than ?(?4) is completely lost when sampling at 1.5 km from the vent for all columns with heights less than 2000 m above the vent. To correct for this effect an optimal sampling strategy and a new reconstruction method are presented. A sensitivity study shows that our method can be extended to a wide range of eruptive scenarios including those in which aggregation processes are important. The new correction method allows an estimate of the deficiency for each simulated class in calculated mass deposited, providing reliable estimation of uncertainties in the reconstructed total (whole deposit) grainsize distribution.  相似文献   

Suitability of energy cone for probabilistic volcanic hazard assessment: validation tests at Somma-Vesuvius and Campi Flegrei (Italy)     

Pablo Tierz  Laura Sandri  Antonio Costa  Lucia Zaccarelli  Mauro Antonio Di Vito  Roberto Sulpizio  Warner Marzocchi 《Bulletin of Volcanology》2016,78(11):79

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Structure of Alluvial Valleys from 3-D Gravity Inversion: The Low Andarax Valley (Almería,Spain) Test Case     

Antonio G. Camacho  Enrique Carmona  Antonio García-Jerez  Francisco Sánchez-Martos  Juan F. Prieto  José Fernández  Francisco Luzón 《Pure and Applied Geophysics》2015,172(11):3107-3121

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