221 research outputs found
Synchrotron microscopic and spectroscopic techniques to reveal the fate of Zn in pioneer plants from abandoned mining sites
Geochemical and mineralogical datasets on waters and stream precipitates from an abandoned mining site: Montevecchio-Ingurtosu district, Rio Irvi (SW Sardinia)
Geochemical modelling data and Powder X-Ray Diffraction data on samples collected along Rio Irvi (Montevecchio-Ingurtosu mining district, SW Sardinia, Italy) are reported in this paper. The data show the results of data processing to calculate water chemical speciation of ions and saturation indices of relevant mineral phases. These data are related with the research article: De Giudici G. et al (2018), Application of hydrologic-tracer techniques to the Casargiu adit and Rio Irvi (SW-Sardinia, Italy): Using enhanced natural attenuation to reduce extreme metal loads, Applied Geochemistry, vol.96, 42–54. The comparison of the calculated saturation indices of relevant Fe-bearing phases with the PXRD data of samples collected along the stream confirm the quality of the SI dataset and the good correlation between the calculations and the observed data. The comparison of this dataset with others can help to deeper understand and quantify the impact of past and current mining activity on water bodies, contributing to implement the scientific background for the application of remediation actions
Fossichnus solus and Oichnus simplex, two peculiar ichnospecies in modern benthic foraminifera from a polluted area in SW coast of Sardinia, Italy
The modern benthic foraminiferal tests collected from a coastal area of south-western Sardinia (Portoscuso-Portovesme) that is heavily polluted by industrial activity reveal intense and widespread bioerosional structures induced by diversifi ed microborers. A large number of the foraminifera reveals microscopic round holes (1-60 ÎĽm in diameter) and roundish concavities (25x40 ÎĽm in external diameter) on their surface that belong, respectively, to the ichnospecies Oichnus simplex Bromley, 1981, and Fossichnus solus Nielsen et al., 2003. These traces just occur in the tests of the foraminifera which are heavily infested by microendolithic cyanobacteria, algae and fungi suggests comparable ethological behaviour between the ichnospecies Fossichnus and Oichnus and the microbial euendoliths that are ascribed to individual biological taxa. The greater occurrence of F. solus and O. simplex in the high-Mg foraminiferal porcelanaceous tests than in the low-Mg foraminiferal hyaline tests reveals that the bioerosional processes seem to be related to the Mg/Ca ratio, as well as to morphological structures of the taxa
MINERALOGICAL STUDIES OF THE W-Sn VEIN SKARNS OF MONTE TAMARA (NUXIS, SULCIS DISTRICT): INSIGHTS FOR STRATEGIC MINERALS EXPLORATION IN SW SARDINIA (ITALY).
Skarn deposits are a relevant source of critical raw materials such as W, Sn, and In. Recent studies conducted in
South Sardinia pointed out the relationships between various Sn-W-Mo deposits and the early Permian (289-286 Ma)
F-bearing, ilmenite-series ferroan granites (e.g., Sulcis pluton). This new evidence triggered a broad re-examination
of granite-related deposits including skarn deposits hosted by Cambrian limestones of the low-grade Variscan
basement of the Sulcis district (SW Sardinia). With this purpose, field investigations and OM, SEM-EDS, EMPA,
and LA-ICP-MS observations, and analyses have been conducted on the skarn ores of Monte Tamara (Nuxis, northern
Sulcis) where scheelite has been reported in the old San Pietro and Sinibidraxiu mines. The San Pietro mine exploited
a 1-5 m thick and 70 m deep, steeply dipping skarn orebody located at the tectonized contact between early Cambrian
sandstones and limestones. The orebody includes layers of Grt-Cpx-Wo, magnetite, and Zn-Pb-Cu-Fe sulfide bands.
Prograde and retrograde stages with oxides and sulfides can be recognized. Clinopyroxene is the foremost mineral
of the prograde stage; garnets (andradite-grossular) are usually dark green with typical anomalous birefringence and
distinctly zoned (Fe-rich cores and Al-rich rims). Hematite turned to mushketovite, and Mo-rich scheelite, followed
by In-bearing cassiterite, occasionally occur in the prograde assemblages. Amphiboles and epidotes mark the
retrograde stage, together with abundant Zn-Cu-Fe-Pb sulfides and accessory molybdenite, stannite, bismuthinite,
and Bi-Ag-Pb sulfosalts. At San Pietro, dominant sphalerite displays highly variable Fe, Mn, and Cd contents. Relictlooking
blebs of Fe-Mn-poor Sp are scattered in high-Fe-Mn Sp where Sn EMPA peaks may correlate with
cassiterite-stannite micro-inclusions. Galena composition suggests localized intergrowths with micro-inclusions of
bismuthinite, Bi-Se, and Bi-Te sulfosalts. The stannite-sphalerite geothermometer provided a temperature range of
325-200°C for the sulfide stage. The Sinibidraxiu old mine exploited a 1,5 m thick and 60 m deep columnar body,
hosted in early Cambrian marbles. It consists of a sphalerite-wollastonite assemblage with late sulfides, quartz, and
calcite, hosting cm-sized arsenopyrite and scheelite. Scheelite is Mo-poor; Sn-, other Mo-phases and Bi-phases are
absent. High-Fe Sp, rimmed by low-Fe Sp and blebby galena, is finely intergrown with wollastonite cockades. The
results from this study suggest that a wide range of skarn-related mineralizing phenomena occurred in the Monte
Tamara area. Both orebodies resulted from a structurally controlled migration of metasomatic fluids inside the hosting
carbonate formation. Mineral zonation and composition of the San Pietro skarn point towards skarn development
under varying fO2 conditions, oxidizing then rapidly turning to moderately reducing within the prograde W-Sn skarn
stage and into the sulfide stage. The features of the Sinibidraxiu orebody (e.g., Mo-poor, As-devoid scheelite) suggest
a formation from reducing metasomatic fluids but S-poor compared to San Pietro, probably at more distal
environments (e.g. low Sn-Bi contents). From this point of view, the Monte Tamara area still maintains an economic
potential, linked to the possible presence of proximal skarn ores at depth; thereby representing a key area for further
exploration for granite-related strategic and critical metals in SW Sardinia
Ex situ phytoremediation trial of Sardinian mine waste using a pioneer plant species
The mitigation of metals contamination is currently a crucial issue for the reclamation of mine sites. Indeed, mine wastes are often disposed in open dumps and consequently pollutants are subjected to dispersion in the surrounding areas. In this study, the potential use of Helichrysum microphyllum subsp. tyrrhenicum for phytostabilization was evaluated in ex situ conditions. Ninety specimens were randomly selected and were planted in three substrates (reference substrate, mine waste materials, and mine wastes with compost). Mineralogical compositions of substrates, rhizosphere, and roots were assessed through X-ray diffraction (XRD). Zn, Pb, and Cd concentrations of substrates, rhizosphere, soil pore waters, and plant tissues were determined. The phytostabilization potential was determined through the application of biological accumulation coefficient (BAC), biological concentration factor (BCF), and translocation factor (TF). Moreover, survival and biometric parameters were assessed on plant specimens. The polluted substrates and related rhizosphere materials were mainly composed of dolomite, quartz, pyrite, and phyllosilicate. Zn was the most abundant metal in substrates, rhizosphere, and soil pore waters. XRD analysis on roots showed the presence of amorphous cellulose and quartz and Zn was the most abundant metal in plant tissues. H. microphyllum subsp. tyrrhenicum restricts the accumulation of the metals into roots limiting their translocation in aereal parts, indicating its potential use as phytostabilizer (BCF, BAC, TF < 1). Survival and growth data showed a great adaptability to different substrates, with an evident positive effect of the implementation of compost which increased the plant survival and decreased the metals uptake into roots
Epidemiology and genetic characterization of <i>Border Disease Virus</i> circulating in Sardinia
Border Disease Virus (BDV), a pestivirus from the Flaviviridae family, is an important pathogen of sheep and goats responsible for significant losses in farms around the world. In spite of the relevance of this pathogen there are only a few epidemiological studies on BDV infection and, as a consequence, the economic impact on small ruminant productions is probably under-estimated. The aims of this study are i) to determine the distribution of BDV in small ruminant farms in Sardinia and genetically characterize circulating strains ii) analyze the relation between seroprevalence, Somatic Cells Count (SCC) an milk yeld. ELISA was performed using “BVDV/MD/BDV p80 Protein Antibody Test Kit” (IDEXX) on serum of bulk tank milk (BTM) samples collected from Sardinian sheep flocks and goat herds between spring 2014 and 2015. The number of sampled farms corresponded to 8.5% of all registered farms in Sardinia. RNA was isolated using Qiamp Viral RNA mini kit from the cellular fraction of each ELISA positive BTV sample and amplified by rt-PCR using complementary primers to a highly conserved region in the untranslated regions (UTRs) of the viral genome. The amplicons were sequenced for phylogenetic analysis. Geographic distribution of collected specimen, seroprevalence and virological positive samples were analyzed via GIS (ESRI ARCGIS 10.3). ELISA screening shows a seroprevalence of 8.3% among goat farms and 10.5% among ovine farms. Ten from the ELISA positive samples were found rt-PCR positive. The sequence analysis indicates that all the amplified samples match with BDV genomes and the phylogenetic analysis revealed that all the viruses clustered in the same group classified as BDV-7. BDV-7 is the only group isolated in Sardinia so far
Mineralogy of the scheelite-bearing ores of Monte Tamara, SW Sardinia: insights for the evolution of a Late Variscan W–Sn skarn system
Southwestern Sardinia, Italy, hosts several skarn, W–Sn–Mo greisen and hydrothermal deposits related to a 289±1 Ma Late Variscan granite suite. Among them, the most representative scheelite-bearing skarns belong to the San Pietro and Sinibidraxiu localities, in the Monte Tamara area, Sulcis region. The San Pietro deposit is a typical calc-silicate skarn whereas Sinibidraxiu is a sharply bounded orebody hosted in a marble unit. Optical petrographic observations and compositional data of major and trace elements were obtained for samples from both localities. San Pietro data suggests evolution from an oxidising prograde skarn stage (andradite–diopside, hematite and scheelite), to progressively more reducing conditions from the early retrograde (magnetite–cassiterite) to the late sulfide stage (arsenopyrite, stannite, molybdenite, Bi sulfosalts and Zn–Cu–Pb–Fe sulfides); Sinibidraxiu has diffuse carbonate–quartz intergrowths pseudomorphic over an early mineral assemblage with fibrous habit, followed by abundant ore mineral precipitation under reducing conditions (scheelite, arsenopyrite and Pb–Zn–Cu–Fe sulfides). Geothermometers indicate a comprehensive temperature range of 460–270°C for the sulfide stages of both deposits. The differences between the two deposits might be controlled by the distance from the source intrusion coupled with the different reactivity of the host rocks. The San Pietro mineralogy represents a more proximal skarn, contrasting with more distal mineralogical and chemical features characterising the Sinibidraxiu orebody (lack of Mo–Sn–Bi phases; LREE–MREE–HREE signature of scheelite). This investigation contributes for the first time to the identification of a W–Sn skarn system in SW Sardinia, thereby suggesting the Monte Tamara area and its surroundings as favourable for further exploration
Fossichnus solus and Oichnus simplex, two peculiar ichnospecies in modern benthic foraminifera from a polluted area in SW coast of Sardina, Italy
The modern benthic foraminiferal tests collected from a coastal area of south-western Sardinia (Portoscuso-Portovesme) that is heavily polluted by industrial activity reveal intense and widespread bioerosional structures induced by diversified microborers. A large number of the foraminifera reveals microscopic round holes (1-60 ÎĽm in diameter) and roundish concavities (25x40 ÎĽm in external diameter) on their surface that belong, respectively, to the ichnospecies Oichnus simplex Bromley, 1981, and Fossichnus solus Nielsen et al., 2003. These traces just occur in the tests of the foraminifera which are heavily infested by microendolithic cyanobacteria, algae and fungi suggests comparable ethological behaviour between the ichnospecies Fossichnus and Oichnus and the microbial euendoliths that are ascribed to individual biological taxa. The greater occurrence of F. solus and O. simplex in the high-Mg foraminiferal porcelanaceous tests than in the low-Mg foraminiferal hyaline tests reveals that the bioerosional processes seem to be related to the Mg/Ca ratio, as well as to morphological structures of the tax
Efficient artificial mineralization route to decontaminate Arsenic(III) polluted water -the Tooeleite Way
Increasing exposure to arsenic (As) contaminated ground water is a great
threat to humanity. Suitable technology for As immobilization and removal from
water, especially for As(III) than As(V), is not available yet. However, it is
known that As(III) is more toxic than As(V) and most groundwater aquifers,
particularly the Gangetic basin in India, is alarmingly contaminated with it.
In search of a viable solution here, we took a cue from the natural
mineralization of Tooeleite, a mineral containing Fe(III) and As(III)ions,
grown under acidic condition, in presence of SO42- ions. Complying to this
natural process, we could grow and separate Tooeleite-like templates from
Fe(III) and As(III) containing water at overall circumneutral pH and in absence
of SO42- ions by using highly polar Zn-only ends of wurtzite ZnS nanorods as
insoluble nano-acidic-surfaces. The central idea here is to exploit these
insoluble nano-acidic-surfaces (called as INAS in the manuscript) as nucleation
centres for Tooeleite growth while keeping the overall pH of the aqueous media
neutral. Therefore, we propose a novel method of artificial mineralization of
As(III) by mimicking a natural process at nanoscale
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