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1.
The deep seismicity of the Tyrrhenian Sea is analysed using data from a new instrumental catalogue of the seismicity of the Italian area. We use algorithms for the determination of absolute and relative hypocentral locations and for the evaluation of the geometry and coherence of the state of stress within the subducting slab. The structure of the Benioff zone, although simpler than previously indicated, reveals anomalous traits both in the seismicity distribution and in the stress geometry, confirming that standard subduction models cannot be applied in the Tyrrhenian region. The velocity anomaly and the location of few isolated events indicate that the subducted slabs extend to the north along the Apenninic chain approximately to the latitude of the Irpinia region, in Central Italy (? 42°N). 相似文献
2.
H. Burtscher P. Cohn L. Scherrer H.C. Siegmann G. Faraci A.R. Pennisi V. Privitera R. Cristofolini V. Scribano 《Journal of Volcanology and Geothermal Research》1987,33(4)
Volcanic aerosol emissions have been studied for the first time by in situ photoelectric charging. Explorative studies on Mt Etna reveal large concentrations of particles below 1000 nm with the spectrum peaking in the size range of 100–1000 nm diameter. Although a large fraction of the particles is already charged upon emission, the net electrical charge carried by the aerosol turned out to be close to zero.Particles with high photoelectric yield vary greatly in their relative abundance and seem to occur mainly at active points of the volcano. 相似文献
3.
R. Petrini M. Pennisi L. Vittori Antisari R. Cidu G. Vianello U. Aviani 《Environmental Earth Sciences》2014,71(12):5099-5111
This paper examines the issues related to salinization and water quality in the complex drainage system of the historical land reclamation of Lamone basin (Ravenna coastal plain, northern Italy), with the aim of guiding ongoing agricultural-related decisions. Major and trace element concentration and O–H–B–Sr isotope-ratios were measured on surface water from a network of canals and ditches. Sampling was carried out during the winter period and in summer, to assess the effects of agricultural water management on the aquatic system. Results show widespread salinization of waters over the entire crop, due to both the direct saltwater inland flushing through the canals in proximity of the mouths, and sea salt leaching from soils. During winter, salinization is partly mitigated by rainfalls, while in summer dilution processes are due to freshwater input from outside the watershed, planned to assist the agricultural water demand. In the winter season, the concentration of some elements such as Fe, Mn, Al, and Cu in waters exceeds the maximum permissible limits imposed by the Italian regulations, while during summer the concentration of these elements is significantly reduced. A seasonal cycling is established, where the bottom sediments of canals and ditches act as sinks of harmful elements, mostly through adsorption by Fe–Mn–Al oxy-hydroxide solid phases. The irrigation practice, although improving the water quality, increases water turbidity by re-mobilization of sediments which act as transport agents of contaminants, with detrimental effects that may become significant over the years. 相似文献
4.
Longoni Laura Ivanov Vladislav Ferrario Maddalena Brunero Marco Papini Monica Arosio Diego 《Landslides》2022,19(3):761-772
Optical fibre–based sensors have now established their place in the field of geohazard monitoring due to their sensitivity to strain and temperature changes. Progressive development in the technology leads to the availability of novel, accurate and durable sensors at a relatively limited cost. This creates room for original monitoring applications that have been, so far, impeded by the shortcomings of conventional monitoring tools. In this work, we explore the applicability of an interferometric optical fibre sensor as a vibration sensing tool at laboratory scale. We tested the ability of the sensor to identify precursors of instability in a downscaled model of a rainfall-induced landslide composed of granular material. We carried out four experimental tests which involved different sensor deployments and soil mixtures. The recorded signals were processed by means of a time–frequency analysis and we identified two frequency-domain parameters—the spectral centroid and band power—that could provide information on the development of instability. Their ratio yielded a unique parameter through which a precursory stage could be outlined by defining a threshold value based on the data collected at the beginning of the experiment. In our lab tests, precursors of instability were detected 2–3 min before a crack was observed at the surface. This may upscale to a lead time of about 20–30 min or more in the field, classifying our monitoring approach in between an alarm and a warning system. The work presented here can be considered a first promising step towards an innovative monitoring system and shows the potential of optical fibre sensing as a shallow landslide monitoring technique, encouraging further testing, especially in real-case studies.
相似文献5.
R. L. Maddalena T. E. McKone D. P. H. Hsieh S. Geng 《Stochastic Environmental Research and Risk Assessment (SERRA)》2001,15(1):1-17
Monte Carlo analysis is a statistical simulation method that is often used to assess and quantify the outcome variance in
complex environmental fate and effects models. Total outcome variance of these models is a function of (1) the variance (uncertainty
and/or variability) associated with each model input and (2) the sensitivity of the model outcome to changes in the inputs.
To propagate variance through a model using Monte Carlo techniques, each variable must be assigned a probability distribution.
The validity of these distributions directly influences the accuracy and reliability of the model outcome. To efficiently
allocate resources for constructing distributions one should first identify the most influential set of variables in the model.
Although existing sensitivity and uncertainty analysis methods can provide a relative ranking of the importance of model inputs,
they fail to identify the minimum set of stochastic inputs necessary to sufficiently characterize the outcome variance. In
this paper, we describe and demonstrate a novel sensitivity/uncertainty analysis method for assessing the importance of each
variable in a multimedia environmental fate model. Our analyses show that for a given scenario, a relatively small number
of input variables influence the central tendency of the model and an even smaller set determines the spread of the outcome
distribution. For each input, the level of influence depends on the scenario under consideration. This information is useful
for developing site specific models and improving our understanding of the processes that have the greatest influence on the
variance in outcomes from multimedia models. 相似文献
6.
Persistent organochlorines, such as polychlorinated biphenyls, including coplanar congeners and DDT compounds, were measured in the liver of a teleost species: namely, Lophius budegassa. The mean concentrations of PCBs (1249 ng/g wet wt) were comparable with DDTs mean levels (1459 ng/g wet wt). Among DDTs the compound found at the highest concentration was p,p'-DDE representing 76% of the total DDT burden. The PCB profiles were dominated by congeners 153, 180, and 138 accounting for 49.8%, 16.0% and 13.7% of the total PCBs. The total 2,3,7,8-TCDD toxic equivalent (TEQs) of six coplanar PCBs, including mono- and non-ortho congeners, was 0.98 pg/g wet wt. The congeners with highest TEQs values were non-ortho-congeners followed by mono-ortho ones. 相似文献
7.
Sonia Tonarini Maddalena Pennisi Alessandra Adorni-Braccesi rea Dini Giorgio Ferrara Roberto Gonfiantini Michael Wiedenbeck Manfred Gröning 《Geostandards and Geoanalytical Research》2003,27(1):21-39
In 1999 the Istituto di Geoscienze e Georisorse (IGG), with the support of the International Atomic Energy Agency (IAEA), undertook the collection, preparation and distribution of eight geological materials intended for a blind interlaboratory comparison of measurements of boron isotopic composition and concentration. The materials came from Italian sources and consist of three natural waters (Mediterranean seawater and two groundwaters) and five rocks and minerals (tourmaline, basalt, obsidian, limestone and clay). The solid materials were crushed, milled and mixed, in preparation for distribution. Extensive assays performed at the IGG on these materials demonstrated that their boron isotopic and chemical compositions are homogeneous.
Additional homogeneity tests were carried out on solid material fragments at the GeoForschungsZentrum Potsdam, with the specific objective of investigating the suitability of some of them for the calibration in situ of micro-analytical techniques. Two materials, B4 (tourmaline) and B6 (obsidian), proved to be isotopically homogeneous and may become excellent references for in situ microanalyses of boron isotopes.
The materials described here were used as the basis of a major laboratory intercomparison study and are now available for further distribution from either the IAEA (solid materials) or the IGG (waters). 相似文献
Additional homogeneity tests were carried out on solid material fragments at the GeoForschungsZentrum Potsdam, with the specific objective of investigating the suitability of some of them for the calibration in situ of micro-analytical techniques. Two materials, B4 (tourmaline) and B6 (obsidian), proved to be isotopically homogeneous and may become excellent references for in situ microanalyses of boron isotopes.
The materials described here were used as the basis of a major laboratory intercomparison study and are now available for further distribution from either the IAEA (solid materials) or the IGG (waters). 相似文献
8.
Concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides (DDTs), were determined in the liver of two different shark species Prionace glauca (blue shark) and Dalatias licha (kitefin shark) from the Mediterranean Sea. In blue shark liver, the concentrations of PCBs (2482 ngg(-1)) and DDTs (2392 ngg(-1)) were comparable, while in kitefin shark the hepatic concentrations of DDTs (4554 ngg(-1)) were significantly higher than those of PCBs (1827 ngg(-1)). Contamination levels differed between species, with kitefin shark showing consistently higher concentrations of DDTs, and blue shark higher levels of PCBs. Congener-specific PCB profiles, similar between the two species were dominated by the higher chlorinated congeners (hexachlorobiphenyls: 62.8-63.9%, penta-: 15.2-21.3%, hepta-: 13.4-14.5%) with most of the lower chlorinated congeners being absent or present at very low levels. In both species, the total 2,3,7,8-tetrachlorodibenz-p-dioxin toxic equivalent (TEQs) concentrations (blue shark: 2.51 pg/g; kitefin shark: 1.46 pg/g) seem to be relatively modest. Regards to DDT component pattern, p,p'-DDE was dominant in the liver of both species (blue shark: 81.5%; kitefin shark: 38.0%), while the percentage composition of the other metabolites was differently characterized. The composition pattern of DDTs and the low value of p,p'-DDE/DDTs ratio in the specimens from Ionian Sea suggest that organochlorine pesticide contamination is still continuing in this marine environment. 相似文献
9.
Sara Bruni Paul Rebischung Susanna Zerbini Zuheir Altamimi Maddalena Errico Efisio Santi 《Journal of Geodesy》2018,92(4):383-399
The realization of the international terrestrial reference frame (ITRF) is currently based on the data provided by four space geodetic techniques. The accuracy of the different technique-dependent materializations of the frame physical parameters (origin and scale) varies according to the nature of the relevant observables and to the impact of technique-specific errors. A reliable computation of the ITRF requires combining the different inputs, so that the strengths of each technique can compensate for the weaknesses of the others. This combination, however, can only be performed providing some additional information which allows tying together the independent technique networks. At present, the links used for that purpose are topometric surveys (local/terrestrial ties) available at ITRF sites hosting instruments of different techniques. In principle, a possible alternative could be offered by spacecrafts accommodating the positioning payloads of multiple geodetic techniques realizing their co-location in orbit (space ties). In this paper, the GNSS–SLR space ties on-board GPS and GLONASS satellites are thoroughly examined in the framework of global reference frame computations. The investigation focuses on the quality of the realized physical frame parameters. According to the achieved results, the space ties on-board GNSS satellites cannot, at present, substitute terrestrial ties in the computation of the ITRF. The study is completed by a series of synthetic simulations investigating the impact that substantial improvements in the volume and quality of SLR observations to GNSS satellites would have on the precision of the GNSS frame parameters. 相似文献
10.
Ruben Bernard Yuri Taran Maddalena Pennisi Enrique Tello Alejandro Ramirez 《Applied Geochemistry》2011,26(12):2064-2073
Geothermal field Los Humeros, Mexico, is characterized by a high steam fraction in the well fluids, by extremely high B concentrations in separated water (grams per liter, with a magmatic B signature, δ11B ± 2σ = −0.8 ± 1.6‰), by the absence of correlation between B and Cl concentrations and by positive correlation between B content in separated water and fluid enthalpy. Such behavior is consistent with the existence of moderately acid brine (pH 3–5) at depth with a high B concentration (500–600 mg/kg). In this case a 3-level model can be suggested for Los Humeros: (1) immature, moderately acid brine at depth which is boiling at a temperature ∼350 °C producing the HCl-bearing vapor with a high B content; (2) partial condensation of this vapor at the upper level accompanying water–rock interaction and neutralization; (3) formation of a shallow water-dominated aquifer above a lithologic low-permeability boundary as has been proposed by other authors. A thermochemical computer code has been used to model boiling of an aqueous fluid at 350 °C with 0.1 M of NaCl, 0.05 M of H3BO3 and variable amount of HCl (0.001–0.1 M), then a partial condensation of the produced vapor at 250 °C and then separation of the steam–water mixture at 150 °C. Results of simulation are in a qualitative agreement with the observed data. 相似文献