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   

Surface moisture area during rainfall–run‐off events to understand the hydrological dynamics of a basin in a plain region          下载免费PDF全文

María Guadalupe Ares  Mauro Holzman  Ilda Entraigas  Marcelo Varni  Luisa Fajardo  Natalia Vercelli 《水文研究》2018,32(10):1351-1362

The understanding of the hydrology of plain basins may be improved by the combined analysis of rainfall–run‐off records and remote sensed surface moisture data. Our work evaluates the surface moisture area (SMA) produced during rainfall–run‐off events in a plain watershed of the Argentine Pampas Region, and studies which hydrological variables are related to the generated SMA. The study area is located in the upper and middle basins of the Del Azul stream, characterized by the presence of small gently hilly areas surrounded by flat landscapes. Data from 9 rainfall–run‐off events were analysed. MODIS surface reflectance data were processed to calculate SMA subsequent to the peak discharge (post‐SMA), and previous to the rainfall events (prev‐SMA), to consider the antecedent wetness. Rainfall–run‐off data included total precipitation depth (P), maximum intensity of rainfall over 6 hr (I6max), surface run‐off registered between the beginning of the event and the day previous to the analysed MODIS scene (R), peak flow (Qp), and flood intensity (IF). In contrast with other works, post‐SMA showed a negative relationship with the R. Three groups of cases were identified: (a) Events of low I6max, high prev‐SMA, and low R were associated with slow and weakly channelized flow over plain areas, leading to saturated overland flow (SOF), with large SMA; (b) events of high I6max, low prev‐SMA, and medium to high R were rapidly transported along the gentle slopes of the basin, related to Hortonian overland flow (HOF) and low post‐SMA; and (c) events of medium to high I6max and prev‐SMA with medium R were related to heterogeneous input‐antecedent‐run‐off conditions combined: Local spatial conditions may have produced HOF or SOF, leading to an averaged response with medium SMA. The interactions between the geomorphology of the basin, the characteristics of the events, and the antecedent conditions may explain the obtained results. This analysis is relevant for the general knowledge of the hydrology of large plains, whose functioning studies are still in their early stages.  相似文献   

The changing Patagonian landscape: Erosion and westward sediment transfer paths in northern Patagonia during the Middle and Late Pleistocene     

Tania Villaseñor  Daniel Tentori  Kathleen M. Marsaglia  Luisa Pinto 《Basin Research》2020,32(5):1035-1053

Pleistocene glaciations have promoted important landscape transformations as a result of high rates of erosion and rapid sediment evacuation to adjacent marine basins. In the Patagonian Andes the role of the Patagonian Ice Sheet on landscape evolution, in particular the spatial patterns of glacial erosion and its influence on sediment fluxes, is poorly documented. Here, we investigate the Middle and Late Pleistocene sedimentary record of the continental slope from Ocean Drilling Program (ODP) Site 861, offshore Patagonia (46°S), to evaluate the link between glaciations, mountain range erosion and continental margin strata formation. Petrographic analysis of the sand-size fraction (0.063–2 mm) and ɛNd and ⁸⁷Sr/⁸⁶Sr measurements in the silt-size fraction (10–63 µm) indicate that glacial erosion over the last 350,000 years has focused within the Patagonian Batholith, with a minor influence of a proximal source to the drilling site, the Chonos Metamorphic Complex. This shows that erosion has focused in the core of the northern Patagonian Andes, coinciding roughly with the location of the Liquiñe-Ofqui Fault Zone and the zone of concentrated precipitation during glaciations, suggesting a combined climatic and structural control on glacial erosion. Temporal variation in the provenance signal is contemporaneous with a marked change in the stratigraphy of ODP Site 861 that occurred after the glaciation of MIS 8 (~240 kyr ago). Before MIS 8, a restricted provenance signal and coarse lithofacies accumulated on the continental slope indicates spatially restricted erosion and efficient transfer of sediment towards the ocean. In contrast, very high provenance variability and finer continental slope lithofacies accumulation after MIS 8 suggest a disorganized expansion of the areas under erosion and a more distal influence of ice sediment discharge to this site. We argue that this change may have been related to a re-organization of the drainage patterns of the Patagonian Ice Sheet and flow of outlet glaciers to the continental margin during the last two glaciations.  相似文献   

The Italian strong motion network   总被引：2，自引：2，他引：0  

Antonella Gorini  Mario Nicoletti  Paolo Marsan  Riccardo Bianconi  Rita De Nardis  Luisa Filippi  Sandro Marcucci  Franco Palma  Elisa Zambonelli 《Bulletin of Earthquake Engineering》2010,8(5):1075-1090

The Italian Strong Motion Network is a permanent monitoring system run by the Italian national emergency management department (Dipartimento della Protezione Civile, DPC). The network is known as RAN (Rete Accelerometrica Nazionale). An extensive project for updating and improving the technology of RAN instruments as well as the number of recording points was performed in the last 10 years. A wide site selection survey was carried out from eastern Sicily along the Italian peninsula, covering high seismic risk areas. The recording station density and the choice of high-quality digital strong motion instruments ensure reliability of the RAN network in the long-term. At the end of 2008, the free field sites selection and instruments installation, planned in the project, were quite completed. In planning and drawing the new RAN, special attention has been devoted to the robustness of the transmission systems, and to the distribution of new stations in order to ensure plenty of data during a seismic emergency. We spent special care both in the estimation of the RAN site responses and in the diffusion of the strong motion data. In order to better identify damaged earthquake areas, improved ground motion parameters need to be set. Such parameters will also assist future progress for engineering seismic design techniques as well as disaster mitigation.  相似文献   

Implications of flow intermittency on sediment nitrogen availability and processing rates in a Mediterranean headwater stream     

María Isabel Arce  María del Mar Sánchez-Montoya  María Rosario Vidal-Abarca  María Luisa Suárez  Rosa Gómez 《Aquatic Sciences - Research Across Boundaries》2014,76(2):173-186

Most streams draining to the Mediterranean basin are temporary. As a result of their hydrological regime, temporary streams are affected by drying and rewetting periods. Drying can alter in-stream nitrogen (N) availability and reduce N processing rates and subsequent retention after re-wetting. We sought to determine if hydrologic drying modifies reach-scale sediment chemical properties and constrains the response of N processing to rewetting. We compared different abiotic characteristics of sediments and nitrification and denitrification rates between a perennial and intermittent reach in the same stream over a wet period, when surface water flowed in both reaches, and a dry period, when the intermittent reach dried up. We analyzed N processing rates by incubating sediments with stream water, thereby simulating a rewetting when sediments from the intermittent reach were dry. We found that drying increased the sediment nitrate (NO₃ ^?) content. Conversely, drying did not reduce the recovery of N processing rates to pre-dry levels after simulated flooding conditions. Our results suggest that dry reaches may act as a potential NO₃ ^? source by releasing downstream NO₃ ^? pulses after stream flow recovery. Given the European Water Framework Directive requirements to assess stream ecological status, these N pulses following rewetting should be considered when designing management plans in temporary streams. Our study highlights the rapid response of in-stream N processing to rewetting period following a drought. This high resilience to process N should be seen as a vital ecosystem service provided by temporary streams despite annual dry periods.  相似文献   

Seismic performance of masonry residential buildings in Lorca’s city centre,after the 11th May 2011 earthquake     

Luisa Basset-Salom  Arianna Guardiola-Víllora 《Bulletin of Earthquake Engineering》2014,12(5):2027-2048

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Strong motion recorded during the Emilia 2012 thrust earthquakes (Northern Italy): a comprehensive analysis     

Rita de Nardis  Luisa Filippi  Giovanni Costa  Peter Suhadolc  Mario Nicoletti  Giusy Lavecchia 《Bulletin of Earthquake Engineering》2014,12(5):2117-2145

A complex seismic sequence characterised by two thrust earthquakes of magnitudes M \(_\mathrm{L}\) 5.9 and M \(_\mathrm{L}\) 5.8 occurred on May 20 and 29, 2012, respectively, and activated the central portion of the Ferrara Arc structure beneath the Po Plain in northern Italy. The sequence, referred to as Emilia 2012, was recorded by the Italian Strong Motion Network, the Irpinia Network, the Friuli Venezia Giulia Network and 15 temporary stations installed by the Civil Protection Department. In this study, we compile and analyse a large dataset that contains 3,273 waveforms from 37 \(M_\mathrm{L} \ge 4.0\) seismic events. The main aim of this paper is to characterise the ground motion induced by the Emilia 2012 seismic sequence and compare it with other data in the Italian strong motion database and to the recent Ground Motion Prediction Equations (GMPEs) developed for northern Italy, all of Italy and Europe. This is achieved by (1) the computation and analysis of the strong motion parameters of the entire Emilia Strong Motion Dataset (ESMD) and (2) a comprehensive investigation of the May 29 event recordings in terms of time–frequency analysis, the ground motion parameters and the response spectra. This detailed analysis was made possible by the temporary Civil Protection Department stations that were installed soon after the May 20 event at several municipalities in the epicentral area. Most of the recordings are characterised by low-frequency content and long durations, which is a result of the thick sedimentary cover that is typical of the Po Plain. The distributions of the observed horizontal peak ground accelerations and velocities (PGAs and PGVs) with distance are generally consistent with the GMPEs. This is particularly true for the data from M \(_\mathrm{L} \ge \) 5.0 (M \(_\mathrm{W}\ge \) 5.0) events, though the data are scattered at distances beyond approximately 60–70 km and show faster attenuation than the European GMPEs. The horizontal components for the May 29 event at two near-fault stations (Mirandola and San Felice sul Panaro) are overestimated by all of the analysed GMPEs. In contrast, the vertical components, which played an important role in the shaking near the source, are underestimated. The May 29 event produced intense velocity pulses on the horizontal components and the highest peak ground acceleration ever recorded in Italy on the vertical component of the Mirandola near-fault station. The ground motion recordings contained in the ESMD significantly enrich the Italian strong motion database. They contribute new information about (1) the possibility of exceeding the largest recorded PGA in Italy, (2) the development of a spectral design that takes into account the role of the vertical component and the extreme variability of the near-fault ground shaking, and (3) the characterisation of the ground motions in deep sedimentary basins.  相似文献   

Scale-Invariance in the Spatial Development of Landslides in the Umbria Region (Italy)   总被引：1，自引：0，他引：1  

Luisa Liucci  Laura Melelli  Cristian Suteanu 《Pure and Applied Geophysics》2015,172(7):1959-1973

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X-ray clusters of galaxies in conformal gravity     

Antonaldo Diaferio  Luisa Ostorero 《Monthly notices of the Royal Astronomical Society》2009,393(1):215-223

We run adiabatic N -body/hydrodynamical simulations of isolated self-gravitating gas clouds to test whether conformal gravity, an alternative theory to general relativity, is able to explain the properties of X-ray galaxy clusters without resorting to dark matter. We show that the gas clouds rapidly reach equilibrium with a density profile which is well fitted by a β-model whose normalization and slope are in approximate agreement with observations. However, conformal gravity fails to yield the observed thermal properties of the gas cloud: (i) the mean temperature is at least an order of magnitude larger than the observed and (ii) the temperature profiles increase with the square of the distance from the cluster centre, in clear disagreement with real X-ray clusters. These results depend on a gravitational potential whose parameters reproduce the velocity rotation curves of spiral galaxies. However, this parametrization stands on an arbitrarily chosen conformal factor. It remains to be seen whether a different conformal factor, specified by a spontaneous breaking of the conformal symmetry, can reconcile this theory with observations.  相似文献   

Daily and annual cycle of CO2 concentration near the surface depending on boundary layer structure at a rural site in Spain     

Isidro A. Pérez  M. Luisa Sánchez  M. Ángeles García  Beatriz de Torre 《Theoretical and Applied Climatology》2009,98(3-4):269-277

CO₂ in the rural atmosphere is related to respiration–photosynthesis processes, although the evolution of the low atmosphere is also a determinant factor. CO₂ concentrations were measured at surface and meteorological variables obtained from a radio acoustic sounding system sodar at a flat rural site during a 3-year campaign. Yearly and daily cycles of CO₂ were described. Maxima were observed in spring and autumn during the night. Wind speed and thermal structure of the lower atmosphere were analysed. Low level jets were observed during the night, their core proving lower in summer. Surface inversions observed with low winds reached up to 100 m. The turbulence layer which developed during the day extended up to 300–400 m and was capped by a stable layer. Median vertical wind speed reached 1 m s^?1 in super-adiabatic conditions in summer. Determination of decoupled low level jets proved difficult with the device used and corresponding concentrations were slightly higher than medians calculated with all the observations. The bulk Richardson number was calculated in the lower atmosphere and four intervals were considered: drainage, transitional, shear flows and unstable conditions. Median CO₂ concentrations were split according to these intervals. Higher values corresponded to drainage flow, which was associated to more stable conditions being less frequent and lower values to shear flow and unstable conditions, revealing a satisfactory link between the bulk Richardson number as a turbulence indicator in the low atmosphere and CO₂ surface concentrations.  相似文献