32 research outputs found

    Analisi della vegetazione del distretto minerario di Montevecchio (Sardegna sud-occidentale)

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    Montevecchio (SW-Sardinia) are presented. The statistic analysis of the relevés let to recognize 14 plant communities. The hygrophilous communities have been ascribed to the class Phragmito-Magnocaricetea, the hemicryptophytic mesohygrophilous ones to Juncetea maritimi, the therophytic to Tuberarietea guttatae and the hemicryptophytic mesoxerophilous to Lygeo-Stipetea. The most interesting vegetation types turned out to be the chamaephytic and nanophanerophytic ones, both kinds are belonging to sardo-corsican endemic alliances: Ptilostemono casabonae-Euphorbion cupanii and Teucrion mari, respectively. The first alliance comprises pebble vegetation with distinctive ecological preferences, as they are able to colonize substrata polluted by heavy metal, with low pH values. Within this alliance, 4 new associations have been recognized: Scrophularietum bicoloris, Dactylo hispanicae-Helichrysetum tyrrhenici, Mercurialido corsicae-Euphorbietum cupanii and Dauco maritimi-Dittrichietum viscosae, the latter with two subassociations (typicum and rumicetosum glaucescentis). As to the Teucrion mari, 1 new association and 1 subassociation have been described (Helichryso tyrrhenici-Genistetum sulcitanae and Stachydi glutinosae-Genistetum corsicae euphorbietosum cupanii), found on aged mining dumps, where the long abandonment made possible the beginning of the pedogenetic processes. The present study let to reconstruct the vegetation dynamics, that in the mining areas are clearly differing from the surrounding territory. It was possible to identify two special series, strictly related to these habitats and verging to the establishment of plant communities pertaining to the climatophilous series: the first is developing on coarse, hard-sloping debris, with very low water retention; the second is developing on fine-grained and coherent materials, found on flattened or gently-sloping sites, with high edaphic humidity. In wetlands, it was also possible to identify an edaphohygrophilous series and a geoseries of endoreic water bodies, not exclusive of the mining habitats

    Aggiornamento alla lista dei <i>syntaxa</i> segnalati per la regione Sardegna (2000-2004)

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    Si segnala l'aggiornamento alla lista dei syntaxa per la Regione Sardegna (2000-2004)

    Integration of vegetational and multitemporal analysis: a case study in the abandoned mine district of Montevecchio (South-Western Sardinia)

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    In this paper the authors analyse the land cover transformation in the mine district of Montevecchio, through the integration of vegetational and multitemporal landscape analysis. Por this purpose, three important dates (1955, 1977, 2000) of the district history have been considered and two different periods are analysed (1955-1977 and 1977-2000). Multitemporal analysis was carried out through thè study of aerial photographs which resulted in the production of three 1:10.000 land cover maps. Vegetational data were obtained through the phytosociological study of the area. The results show the evolution of the natural vegetation as general trend in the territory. Particular analysis was carried out on the mining areas (mining dumps, surface mines and tailing dams) to understand how much and how have been re-colonized by thè native vegetation. Por the mining dumps the main transformations are towards thè mediterranean maquis, the garrigue and thè corkoak woods. The surface mines was stable in the first period for 73.6% and thè main changes are due to the diffusion of naturai vegetation (e.g. to mediterranean maquis 14.7%). With regard to the tailing dams we observed an increase of stability (from 81.6% to 96.1%) together with a global increase of surface from 1955 to 2000. Therefore, thè integration of thè multitemporal and the vegetational analysis made possible to register a significant evolution of thè vegetation cover on incoherent and polluted materials in relatively short times

    Native Plant Capacity for Gentle Remediation in Heavily Polluted Mines

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    This research was funded by Research Groups RNM-269 and RNM-207 (Junta de AndalucĂ­a, Spain).The authors would like to thank Francisco J. MartĂ­n Peinado for their help with the portable field X-ray fluorescence analyzer NITON XLt 792. We would also like to thank D. Nesbitt for improving the English.The use of plant species to stabilize and accumulate trace elements in contaminated soils is considered of great usefulness given the difficulty of decontaminating large areas subjected to mining for long periods. In this work, the bioaccumulation of trace elements is studied by relating the concentrations in leaves and roots of three plants of Mediterranean distribution (Dittrichia viscosa, Cistus salviifolius, Euphorbia pithyusa subsp. cupanii) with the concentrations of trace elements in contaminated and uncontaminated soils. Furthermore, in the case of D. viscosa, to know the concentration of each element by biomass, the pool of trace elements was determined both in the aerial part and in the roots. The bioaccumulation factor was not high enough in any of the species studied to be considered as phytoextractors. However, species like the ones studied in this work that live on soils with a wide range of concentration of trace elements and that develop a considerable biomass could be considered for stabilization of contaminated soils. The plant species studied in this work are good candidates for gentle-remediation options in the polluted Mediterranean.Junta de Andaluci

    Use of native species and biodegradable chelating agents in the phytoremediation of abandoned mining areas

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    Abstract BACKGROUND: The application of phytostabilization and assisted phytoextraction to the remediation of abandoned mining areas can be a valuable method to reclaim these areas without modifying soil and landscape characteristics. An in situ application of a continuous phytoextraction technique was carried out in the area of Campo Pisano (Sardinia, Italy), followed by a laboratory assisted phytoextraction test using the biodegradable chelating agents methylglycine diacetic acid (MGDA) and iminodissuccinic acid (IDSA). The plants used were Scrophularia canina subsp. bicolor, Cistus salviifolius and Teucrium flavum subsp. glaucum

    Metrology on-board PROBA-3: The Shadow Position Sensor (SPS) subsystem

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    PROBA-3 is an ESA Mission whose aim is to demonstrate the in-orbit Formation Flying and attitude control capabilities of its two satellites by means of closed-loop, on-board metrology. The two small spacecraft will form a giant externally occulted coronagraph that will observe in visible polarized light the inner part of the solar corona. The SPS subsystem is composed of eight sensors that will measure, with the required sensitivity and dynamic range, the penumbra light intensity around the coronagraph instrument entrance pupil

    Metrology on-board PROBA-3: The shadow position sensors subsystem

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    PROBA-3 is an ESA mission aimed at the demonstration of formation flying performance of two satellites that will form a giant coronagraph in space. The first spacecraft will host a telescope imaging the solar corona in visible light, while the second, the external occulter, will produce an artificial eclipse. This instrument is named ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun). To accomplish the payload's scientific tasks, PROBA-3 will ensure sub-millimeter reciprocal positioning of its two satellites using closed-loop on-board metrology. Several metrology systems will be used and the Shadow Position Sensor (SPS) subsystem senses the penumbra around the instrument aperture and returns the 3-D displacement of the coronagraph satellite, with respect to its nominal position, by running a dedicated algorithm. In this paper, we describe how the SPS works and the choices made to accomplish the mission objectives

    An improved version of the Shadow Position Sensor readout electronics on-board the ESA PROBA-3 Mission

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    PROBA-3 [1] [2] is a Mission of the European Space Agency (ESA) composed by two satellites flying in formation and aimed at achieving unprecedented performance in terms of relative positioning. The mission purpose is, in first place, technological: the repeated formation break and acquisition during each orbit (every about twenty hours) will be useful to demonstrate the efficacy of the closed-loop control system in keeping the formation-flying (FF) and attitude (i.e. the alignment with respect to the Sun) of the system. From the scientific side, instead, the two spacecraft will create a giant instrument about 150 m long: an externally occulted coronagraph named ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) dedicated to the study of the inner part of the visible solar corona. The two satellites composing the mission are: the Coronagraph Spacecraft (CSC), hosting the Coronagraph Instrument (CI), and the disk-shaped (1.4 m diameter) Occulter Spacecraft (OSC). The PROBA-3 GNC (Guidance, Navigation and Control) system will employ several metrological subsystems to keep and retain the desired relative position and the absolute attitude (i.e. with respect to the Sun) of the aligned spacecraft, when in observational mode. The SPS subsystem [5] is one of these metrological instruments. It is composed of eight silicon photomultipliers (SiPMs), sensors operated in photovoltaic mode [6] that will sense the penumbra light around the Instrument's pupil so to detect any FF displacement from the nominal position. In proximity of the CDR (Critical Design Review) phase, we describe in the present paper the changes occurred to design in the last year in consequence of the tests performed on the SPS Breadboard (Evaluation Board, EB) and the SPS Development Model (DM) and that will finally lead to the realization of the flight version of the SPS system

    The shadow position sensors (SPS) formation flying metrology subsystem for the ESA PROBA-3 mission: present status and future developments

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    PROBA-3 [1] [2] is a Mission of the European Space Agency (ESA) composed of two formation-flying satellites, planned for their joint launch by the end of 2018. Its main purposes have a dual nature: scientific and technological. In particular, it is designed to observe and study the inner part of the visible solar corona, thanks to a dedicated coronagraph called ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), and to demonstrate the in-orbit formation flying (FF) and attitude control capability of its two satellites. The Coronagraph payload on-board PROBA-3 consists of the following parts: the Coronagraph Instrument (CI) with the Shadow Position Sensor (SPS) on the Coronagraph Spacecraft (CSC), the Occulter Position Sensor (OPSE) [3] [4] and the External Occulting (EO) disk on the Occulter Spacecraft (OSC). The SPS subsystem [5] is one of the main metrological devices of the Mission, adopted to control and to maintain the relative (i.e. between the two satellites) and absolute (i.e. with respect to the Sun) FF attitude. It is composed of eight micro arrays of silicon photomultipliers (SiPMs) [6] that shall be able to measure, with the required sensitivity and dynamic range as asked by ESA, the penumbral light intensity on the Coronagraph entrance pupil. With the present paper we describe the testing activities on the SPS breadboard (BB) and Development Model (DM) as well as the present status and future developments of this PROBA-3 metrological subsystem
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