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排序方式: 共有126条查询结果,搜索用时 15 毫秒
61.
Waste rock dump investigation at Roşia Montană gold mine (Romania): a geostatistical approach 总被引:1,自引:1,他引:0
Diego Servida Sara Comero Mara Dal Santo Luisa de Capitani Giovanni Grieco Pietro Marescotti Silvia Porro Ferenc Lázár Forray Ágnes Gál Alexandru Szakács 《Environmental Earth Sciences》2013,70(1):13-31
Ro?ia Montan?, the largest European gold mine, could be re-opened. Environmental problems led to severe pollution of the Ro?ia and Abrud Rivers. The two main potentially toxic element (PTE) sources in mine sites are, in general, the abandoned underground workings and the piles of waste rock. Since the composition of waste rocks is often heterogeneous, this study faces the problem of estimating their mineralogical and chemical features starting from a set of sampling point. Twenty-five samples were collected on the main waste dump of the Ro?ia Montan? mine following a virtual squared grid (knots distance about 25 m). Grain size, color, bulk chemistry, mineralogy, acid mine drainage potential and a set of selected PTE (Ag, As, Cu, Ni, Pb and Zn) concentrations were determined on each sample. In a first approximation two main waste rock groups were identified: WR1 bulk composition is dacite-dominated, while WR2 is andesite-dominated. In both of them the concentrations of PTEs are below the regulatory limits for soils, with the exception of As. In terms of acid mine drainage, WR1 has a net acid-producing potential, while WR2 has a net neutralizing potential. The anisotropy of WR properties were analysed by means of semi-variograms and displayed with contour maps. Application of positive matrix factorization for the analysis of all the data relative to waste rocks allowed defining, in a semi-quantitative way, the factors controlling pollution and their spatial distribution. The processing of score matrix G factor associated with the geostatistical elaboration promises to be a powerful tool to discern the composition of mine dumps and support the exploitation and remediation phases. 相似文献
62.
In ancient times, the name “Peloro” was used to indicate an anthropic area that gradually developed around the first known human settlement on the Sicilian shore near the Straits of Messina. Since the 5th century BC, historians have documented that numerous naval armadas landed for long periods at Peloro. However, the present-day morphology of the Peloro Cape Peninsula does not have any protected inlet that would offer a location to repair hundreds of ships, as has been documented by historical sources. To address this discrepancy, geomorphologic data were collected and analyzed to verify whether historical documents were consistent with the palaeotopography of the area. This approach is based on the analysis of the morphotectonic evolution of the coastal lowland that resulted from regional uplift over the Quaternary and Holocene. The results indicate that the harbour was located in the basin of the Pantano Piccolo salt marsh, and was large and deep enough to have sheltered up to 320 ships. 相似文献
63.
A study has been made of the time evolution of the flux of moisture E over grassland. The parameterization of E has been examined in order to formulate an equation depending on the net radiation flux and on bulk parameters which depend on the daily average meteorological situation and soil conditions. In particular the gradient of soil moisture has been recognized as playing a fundamental role in the time evolution of E(t). A time-dependent equation is proposed to compute in a statistical sense the irrigation needs or to forecast the hourly values of E(t), the maximum value E
0 and the time at which this maximum happens. 相似文献
64.
Experiments on degassing of water-saturated granite melts with a pressure drop from 100 and 450 MPa to 40 and 120 MPa, respectively,
at temperatures close to feldspar liquidus (750–700 °C), were carried out to determine the modality of water exsolution and
vesicle formation at the liquidus temperature. Pressure-drop rates as small as approximately 100 bar/day were used. Uniform
space distributions of bubbles of exsolved water were obtained with starting glass containing a small fraction (≈0.5 vol.%)
of trapped air bubbles. Volume crystallization of feldspar was observed in degassed melts supplied with seeds. Bubble size
distributions (BSD) measured in granite glasses after degassing are presented. Data on vesicle characteristics (number, radius,
area, elongation) were acquired on images digitized with standard software, while the reconstruction of size distributions
was performed with the Schwartz-Saltikov "unfolding" procedure. Bubble size distributions of size classes in the range 5–1000 μm
were acquired with proper magnification and satisfactory statistical reliability of determined number densities. The BSDs
of the experimental samples are compared with the results of measurements of rapidly degassed products of Mt. Etna and Vulcano
Island. Many particular features of the bubble nucleation and growth can be distinguished in an individual BSD. However, the
general BSD of the whole data set, including natural ones, can be relatively well described with linear regression in bilogarithmic
coordinates. The slope of this regression is approximately 2.8±0.1. This dependence is in striking contrast with distributions
theoretically predicted with classical nucleation models based on homogeneous nucleation of vesicles. The theoretical distribution
requires the occurrence of strong maxima that are not observed in our experimental and natural samples, thus arguing for heterogeneous
nucleation mechanisms.
Received: 1 October 1998 / Accepted: 25 June 1999 相似文献
65.
A warning system for rainfall-induced shallow failures 总被引:22,自引:0,他引:22
It is widely recognised that soil slips and debris flows are triggered by short intense storms. Owing its geologic, geomorphologic and climatic settings, the Piedmont Region (NW Italy) is highly prone to the occurrence of this kind of landslides. In the last two centuries, in fact, a total of 105 severe meteoric events which triggered shallow failures occurred and, of these, 18 events took place from 1990 to 2002. A fair number of rainfall thresholds have been proposed in the literature, defined both on empirical or on physical bases. Empirical thresholds are defined collecting rainfall data for landslide meteoric events and for events without landslides, while physical thresholds are based on numerical models that consider the relation between rainfall, pore pressure and slope stability. The main objective of this paper is the identification of the empirical triggering thresholds for the Piedmont Region. Four meteoric events were selected and analysed (November 4–5, 1994; July 7–8, 1996; April 27–30, 2000; October 13–16, 2000) because they supply a wide range of variation for both rainfall parameters (duration, intensity, cumulative rainfalls) and the number of induced landslides. In the intensity–duration plot, the critical limit is described by the equation: I=19D−0.50 (where I=rainfall intensity expressed in mm/h and D=rainfall duration expressed in hours). Such a limit is traced to envelop 90% of the points on the graph. In the NI–D diagram the triggering thresholds are given by the equations NI=0.76D−0.33 and NI=4.62D−0.79 (where NI=normalised intensity with respect to the annual precipitation, MAP, expressed in %, [(mm/h)/PMA]×100). In the article the different meaning of these thresholds is discussed. Finally, the diagram NI–NCR is proposed; the triggering threshold is given by the expression: NI=−0.09ln[NCR]+0.54 (where NCR is the normalised cumulative critical rainfall, [mm/PMA]×100). The application of the triggering thresholds as a fundamental element in a warning system dedicated to the safeguarding of population in landslide-prone areas is discussed. In detail an operating procedure which is presently being verified and tested in the studied area is described. 相似文献
66.
Guglielmo Rossi Luca Tanteri Veronica Tofani Pietro Vannocci Sandro Moretti Nicola Casagli 《Landslides》2018,15(5):1045-1052
This paper presents the preliminary results of the IPL project 196 “Development and applications of a multi-sensor drone for geohazards monitoring and mapping.” The objective of the project is to test the applicability of a multi-sensor drone for the mapping and monitoring of different types of geohazards. The Department of Earth Sciences of the University of Florence has developed a new type of drone airframe. Several survey campaigns were performed in the village of Ricasoli, in the Upper Arno river Valley (Tuscany, Italy) with the drone equipped with an optical camera to understand the possibility of this rising technology to map and characterize landslides. The aerial images were combined and analyzed using Structure-from-Motion (SfM) software. The collected data allowed an accurate reconstruction and mapping of the detected landslides. Comparative analysis of the obtained DTMs also permitted the detection of some slope portions being prone to failure and to evaluate the area and volume of the involved mass. 相似文献
67.
Gazzola Laura Ferronato Massimiliano Frigo Matteo Janna Carlo Teatini Pietro Zoccarato Claudia Antonelli Massimo Corradi Anna Dacome Maria Carolina Mantica Stefano 《Computational Geosciences》2021,25(5):1751-1751
Computational Geosciences - A Correction to this paper has been published: https://doi.org/10.1007/s10596-021-10079-6 相似文献
68.
Maurizio Previati Davide Canone Edoardo Iurato Davide Gisolo Stefano Ferrari Pietro Teatini Mario Putti Stefano Ferraris 《水文研究》2020,34(5):1269-1284
A peat deposit (Zennare basin, Venice coastland, Italy) was monitored in previous field studies to investigate the hydrological response of organic soil to meteorological dynamics. Field tests and modelling predictions highlighted the risk of the complete loss of this peat layer during the next 50 years, due to oxidation enhanced by the increased frequency of warmer periods. Unfortunately, despite the considerable impacts that are expected to affect peat bogs (in this area and worldwide), only a few experimental studies have been carried out to assess the hydrologic response of peat to severe water scarcity. Because of that, an undisturbed 0.7 m3 peat monolith was collected, transferred to the laboratory and instrumented. The total weight (representative of the water content dynamics of the peat monolith as a whole), and two vertical profiles of matric potentials and water content were monitored in controlled water-scarce conditions. After an extended air-drying period, the monolith was used as an undisturbed peat lysimeter and a complete cycle of wetting and drainage was performed. Supplementary measurements of matric potential ψ and water content θ were collected by testing peat subsamples on a suction table apparatus. A set of water retention curves was determined in a range of matric potentials broader (ψ down to −7 m) than the current natural conditions in the field (minimum ψ = −1 m). While water content at saturation showed values similar to those in the original natural conditions (θ ≅ 0.8), a remarkable loss of water holding capacity (even for low potentials) has been highlighted, especially in deep layers that are now permanently below the water table. The retention curves changed shape and values, with a more pronounced hysteresis visible in an increasing distance between wetting and drying data. Hydraulic non-equilibrium between the water content and water potential could be a possible cause and it is worth modelling in future studies. The parameters of the van Genuchten retention curves were obtained for the wetting and the drying phases. 相似文献
69.
Sophie A. Murray Jordan A. Guerra Pietro Zucca Sung-Hong Park Eoin P. Carley Peter T. Gallagher Nicole Vilmer Volker Bothmer 《Solar physics》2018,293(4):60
Coronal mass ejections (CMEs) and other solar eruptive phenomena can be physically linked by combining data from a multitude of ground-based and space-based instruments alongside models; however, this can be challenging for automated operational systems. The EU Framework Package 7 HELCATS project provides catalogues of CME observations and properties from the Heliospheric Imagers on board the two NASA/STEREO spacecraft in order to track the evolution of CMEs in the inner heliosphere. From the main HICAT catalogue of over 2,000 CME detections, an automated algorithm has been developed to connect the CMEs observed by STEREO to any corresponding solar flares and active-region (AR) sources on the solar surface. CME kinematic properties, such as speed and angular width, are compared with AR magnetic field properties, such as magnetic flux, area, and neutral line characteristics. The resulting LOWCAT catalogue is also compared to the extensive AR property database created by the EU Horizon 2020 FLARECAST project, which provides more complex magnetic field parameters derived from vector magnetograms. Initial statistical analysis has been undertaken on the new data to provide insight into the link between flare and CME events, and characteristics of eruptive ARs. Warning thresholds determined from analysis of the evolution of these parameters is shown to be a useful output for operational space weather purposes. Parameters of particular interest for further analysis include total unsigned flux, vertical current, and current helicity. The automated method developed to create the LOWCAT catalogue may also be useful for future efforts to develop operational CME forecasting. 相似文献
70.
Pietro Passerini 《Environmental Geology》1984,6(4):211-221
The anthropostrome is used to denote the collective constructs of human artifacts and is characterized by repetitive geometrical
moduli, centralized energetic cyclons, and constrictive restraints to functional freedom of both human and non-human elements.
This unified, self-perpetuating, man-made environment is a high-level integrative structure where organism-like features are
developing while ocosystem-like features persist. Due to pervasive integration, urban-industrial men generally fail to perceive
the colonial nature of the autonomous unit which produced them Direct contacts with the world outside the anthropostrome are
scare, and most information and sensory experience are supplied by the anthropostrome itself
In spite of temporary or localized regressions, the global trend is apparently toward growth of the total anthropostrome Expansion
of urban systems will presumably be accelerated until environmental degradation and resource shortages act as natural constraints
The need for containment of the anthropostrome’s growth and for control of its swift noogentic development while avoiding
injury to men is possibly the next challenge to man’s evolutionary potential 相似文献