272 research outputs found
Application of Electrical Resistivity Ground Imaging (ERGI) to aid the Acid Mine Drainage (AMD) evaluation in the Rio Marina mining district (Elba Island)
No full textThe Rio Marina mining district (Elba island) was one of the greatest Italian iron ore and was exploited till 1981. Nowadays it is used as an excursion site and it is famous all around the world for its hematite-pyrite mineralogical samples and for its multi-colour acid pools. These pools are related to Acid Mining Drainage (AMD) process that occur in the sulfide-mining area. The effect of open-pit mining and other mining-related activities is that sulfides, previously isolated from the atmosphere, are exposed to oxygen. The oxidation of sulfides acidifies the flowing waters that leach ore minerals and dissolve elements such as arsenic, copper, manganese, iron, lead and zinc. This process leads to environmental pollution. The Rio Marina mining district is currently object of a geo-environmental characterization to assess hazard and persistence of the AMD process (Servida et al. 2006). In addition to investigations on surface waters, terrains and topographic evolution of the mining site, a geo-environmental model aiming to AMD evaluation requires the determination of: 1) waste rock thickness, to evaluate the amount of sulfuric acid that could be produced and the content of heavy metals that could be leached from terrains; 2) distribution of sulfides in the waste deposits; 3) distribution of the water-rich zones in waste deposits. The aim of this work is to supply these data by means of 2-D Electrical Resistivity Ground Imaging (ERGI) techniques. The pilot-study was performed on the Antenna plains, which represent one of the waste disposals of Rio Marina district. This area was chosen since 3-D topographical modelling, field survey and bibliographic data show no certain information concerning the thickness of the waste deposits. The following procedure was adopted: 1)acquisition of five ERGI profiles over the Antenna plains and identification of bodies showing homogeneous distribution of electrical resistivity. ERGI profiles were acquired by means of Wenner-Schlumberger array with 44 electrodes, with electrodes-spacing ranging from 3.0 to 5.0 m (maximum depth of investigation = 40.0 m). Profiles were acquired on a square grid in order to investigate the 3-D features of the subsurface; 2) direct-calibration of electrical resistivity class-values of bedrock (60-150 Ohm*m) and hematite-pyrite mineralized ore bodies (10-30 Ohm*m) by acquisition of 1 ERGI profile (Wenner-Schlumberger array; 30 electrodes, electrode-spacing = 2,5 m) located on an exposed quarry bench in the proximity of the Antenna plains; 3) interpretation of electrical resistivity distribution obtained by ERGI profiles by the light of a) the model of subsurface from 1954-1979 topographic and mining maps, b) knowledge of ore-geological model of the mining area, c) electrical resistivity obtained from the direct-calibration made on the outcropping analogue materials, d) physical and chemical properties of surface waters and terrains;
4) 3-D interpolation by geostatistical analysis (kriging) of the boundary between the electrical resistivity bodies correlated to bedrock-ore bodies complex and the hypothesized waste deposits. The results show that: 1) Antenna plains are composed by waste deposits with a maximum depth of about 25.0 m. These data confirm that Antenna was an old open-pit used as a mine-waste dump; 2) waste deposits have highly-conductive homogeneous electrical properties (<10 Ohm*m) and, consequently, they could have an homogeneous water-content and chemical composition. The low resistivity value is due to the high conductivity of groundwater (average groundwater conductivity: 7.54 mS/cm = 1.3 Ohm*m) and the occurrence of clay minerals produced by in-situ weathering of bedrock and debris; 3) bedrock has highly-conductive anomalies (10-30 Ohm*m) that, from their geometry, position and electrical resistivity values, could be interpreted as hematite-pyrite mineralized ore bodies
Hazard and persistence evaluation of Acid Mine Drainage (AMD) process in Valle Giove mining area (Rio Marina district, Elba Island)
No full textElba island mining activity has been documented since Roman times and was related mainly to iron exploration and exploitation in three districts: Rio Marina, Rio Albano and Capoliveri. Valle Giove is the greatest open pit of the Rio Marina district with 0.5 km2 and is characterized by a hematite + pyrite ± magnetite ± sphalerite ± chalcopyrite ± galena ± bismuthinite ± anglesite ± cerussite ± native sulfur ore association (Tanelli et al., 2001) occurring in strata, lens or vein deposits (Zuffardi, 1990). The effect of open pit mining and other mining-related activities is that sulfides previously isolated from the atmosphere are exposed to oxygen. The oxidation of sulfides acidifies flowing waters that leach ore minerals and dissolve elements such as arsenic, copper, lead, manganese, iron and zinc (Blowes et al., 2003). All these steps, leading to environmental pollution, are known as Acid Mine Drainage (AMD). At Valle Giove AMD process occurs as testified by all the sampled waters (Giove stream, drainage channels, surficial pools and settling basin) which have pH values ranging from 2.08 to 3.35 and an heavy metals content that reaches 903.16 mg/l for Fe, 45.02 mg/l for Mn, 10.08 mg/l for Zn and 1.75 mg/l for Cu. For a preliminary AMD hazard evaluation a central aligned 100 m mesh square grid sampling (EPA, 2002) was performed and fifty-four different terrain samples (residual soils, waste rocks or debris materials) were collected. They were analysed for major elements by XRF and for trace elements by ICP-AES. Net Acid Producing Potential (NAPP) of terrains was determined following AMIRA procedure (IWRI & EGI, 2002). In addition, spatial distribution of heavy metals and hazard assessment of AMD process were investigated using statistical and geostatistical techniques. Moreover, 3-D Digital Terrain Model (DTM) of the mining area at the beginning (1954) and close to the end (1979) of exploitation were developed using AutoCAD 2004 and SURFER 8 software. The comparison between the two periods shows the distribution of topographical positive (mining waste disposals) and negative variations (quarrying areas) and leads to estimate the volume of the material removed from the mining area in the order of 1.38*106 m3 and the volume of material discharged in the same area in the order of 1.57*103 m3. The latter value must be adjusted with additional investigations since the first-mined open pits next to Valle Giove were used as mine waste dumps (Servida et al., in progress). According to the obtained data three main hazard classes were established and their distribution in the mining area was assessed. About 46% of the mining area surface belongs to class I, where AMD process occurs (NAPP>0 and heavy metals content exceeds law limits), about 52% belongs to class II, where AMD process could occur only if some conditions are satisfied (NAPP>0 and heavy metals content is lower than law limits or NAPP<0 and heavy metals content exceeds law limits), only 2% belongs to class III, where AMD process cannot occurs (NAPP<0 and heavy metals content under law limits). Finally, the persistence of AMD process at Valle Giove was evaluated starting from yearly rainfall, mining waters pH and NAPP values. A complete leaching of the first 0.25 m of the terrains can retain the current environmental conditions for several centuries
Characterisation of sulphide-bearing waste-rock dumps using electrical resistivity imaging: the case study of the Rio Marina mining district (Elba Island, Italy)
No full textSulphide-bearing mine dumps are potential sources of pollution when acid mine drainage (AMD) occurs. Because the generation of AMD depends on the volume and composition of waste materials, their characterisation is crucial for the evaluation of geochemical hazards and for the design of remediation strategies to minimise their environmental impact. In this paper, a cost-effective strategy for the characterisation of an inactive mine dump in the Rio Marina mining district (Elba Island, Italy) using earth resistivity imaging (ERI) is presented. As no information regarding the nature of waste rocks is found in reports for the mine, five ERI profiles were acquired at the top of the waste pile. The results show that waste rocks are heterogeneous with a maximum thickness of 30 m. Due to the large amounts of dispersed sulphide minerals,
the waste rocks are characterised by an electrically conductive geophysical signature in comparison to the surrounding resistive metamorphic bedrock. A geostatistical approach was adopted to estimate the elevation of the edges of the mine dump, and the net
volume of the waste rocks was computed through a raster analysis of the elevations of the upper and lower boundaries of the mine dump. High-conductivity anomalies were detected within the core of the mine
dump. The integration of the hydrogeological, geochemical
and geological framework of the Rio
Marina mining district suggests that these anomalies could be a geophysical signature of subsurface regions
where AMD is currently generated or stored, thus representing sources of environmental pollution
Phreatic Sulfide-bearing Quartz Breccias (SQB) between Crystalline Basement and Collio Formation (Southern Alps, Italy)
No full textIn questo lavoro vengono presentate le caratteristiche geologiche, petrografiche e minerografiche di alcune brecce quarzose mineralizzate a solfuri che affiorano in un’area complessa delle Alpi Orobie (Subalpino), nei pressi dell’area uranifera di Novazza. Sebbene poco studiate, queste brecce sono state attribuite in passato a differenti processi genetici e/o formazioni geologiche (es: Basamento Cristallino, Conglomerato Basale), ma i caratteri riscontrati sembrano confermare una loro origine idrotermale, probabilmente legata allo stesso processo che ha generato il giacimento di U a Novazza
Sostenibilità ambientale, autonomia privata e private regulation
No full textIl contributo indaga quali siano le ricadute sull’autonomia privata delle politiche ambientali dell’Unione europea, esplorando la possibilità che la sostenibilità ambientale sia una norma dotata di efficacia orizzontale, applicabile ai rapporti contrattuali di impresa. Più nel dettaglio, si vuol verificare se il principio dello sviluppo sostenibile costituisca un limite interno all’autonomia privata e, per altro verso, alla capacità di autoregolamentazione delle imprese, anche alla luce dell’art. 25 della proposta di Direttiva sulla due diligence delle società ai fini della sostenibilità. Acclarato che l’imposizione di misure limitative dell’autonomia privata è sempre coperta da riserva di legge e, d’altro canto, che la violazione di una clausola generale – come quella dello sviluppo sostenibile – non può mai condurre alla nullità del contratto, ci si concentra sul ruolo dell’autoregolamento privato nella governance ambientale. In questa prospettiva svolgono un ruolo cruciale gli strumenti di c.d. accountability e trasparenza introdotti dal Legislatore europeo, che si inseriscono nell’ambito di una strategia di responsabilizzazione dell’impresa che mira a superare il modello della pura disclosure per intervenire sulle modalità di esercizio dell’attività di impresa, anche nell’interesse della vasta platea di stakeholder coinvolti
Kinetics of P-xylene Liquid-phase Catalytic-oxidation
No full textA semibatch gas-liquid reactor model based on a lumped kinetic scheme for the liquid-phase oxidation of p-xylene to p-toluic acid catalyzed by cobalt naphtenate is developed. The model accounts for the complex nature of the involved reaction network, as well as for the interphase and interphase mass transport processes of both reactants and products. The model reliability is tested by comparison with suitable experimental data obtained in a semibatch oxidation reactor, where the role of the composition of both the gaseous and the liquid feed has been investigated. It is shown that the model describes the reactor behavior in any of the regimes which may prevail depending upon the operating conditions and the depletion of liquid reactants in time
Spectroscopic and spectromagnetic study of adenosine chloroderivatives of bivalent Co, Ni, Cu, Zn, Cd. Comparison with the corresponding adenine chloroderivatives
No full text[M′′LnCl2] (n = 1,2) (M′′= Co, Ni, Cu, Zn, Cd, Hg) (L = adenine, adenosine) compounds were synthesized and the magnetic, electronic and vibrational properties of adenosine derivatives were considered in comparison with those of adenine complexes. It was found that the ligand field symmetry is distorted tetrahedral in cobalt, zinc compounds and in CuLCl2; distorted octahedral in Ni, Cd, Hg compounds and in CuL2Cl2. Sugar moiety of adenosine is not implied in the coordination to the metal center. Distortions from regular symmetries were recognized by ESR measurements and confirmed by vibrational analysis; it resulted an higher distorting power of adenosine than of adenine. Both monodentate and bridging N(3)-N(9) or N(1)-N(7) coordination were discussed. The MN bond strength resulted higher for bridged coordination. ESR sensitive change of spin state were observed in CoL2Cl2 compounds. Vibrational measurements on purine absorption modes suggest that the ligand is not strongly perturbed by the metal coordination. © 1981
Evaluation of immunological, stress and behavioural parameters in dogs (canis familiaris) with anxiety-related disorders
No full textEffect of transport on rabbit’s welfare: serum lysozyme determination
No full textThe aim of this study was to determine the influence of transport and lairage on serum lysozyme concentration to study animals’ stress. Lysozyme is considered as a component of the earlier protective mechanisms. Studies of the stress influence on lysozyme concentration are scarce. In this work the effects exerted on welfare by different times of journey (1 vs 3h) and lairage (0 vs 5h) were tested on 70 rabbits. To analyse lysozyme, two blood samples have been taken immediately before and after the animal transport and lairage. Lysozyme concentration was determined using a micromethod assay set up at DIPAV starting from the lysoplate Ossermann’s method. In short transport without lairage (14.7±8.8 vs 11.8±6.6 μg/ml) and short transport with lairage (8.9±3.0 vs 6.0±3.6 μg/ml) groups, a decrease of lysozyme activity was observed after transport, whereas in long transport without lairage (7.4±2.3 vs 9.4±3.9 μg/ml) and long transport with lairage (13.7±11.3 vs 16.8±13.0 μg/ml) groups, an increased activity after transport was noticed from initial values. Probably transport leads to changes in neuroendocrine and immune system-derived substances, which influence the innate immune factors, but a detailed explanation of these mechanisms needs some additional studies
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