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Local order and valence state of Fe in urban suspended particulate matter
No full textX-ray absorption spectroscopy investigations were carried out on urban suspended particulate matter (PM2.5) with the aim of studying the local order and valence state of iron, a metal abundant in this type of material, particularly in urban environments. XANES results, based on the comparison with model compounds fayalite (Fe2+) and ferrihydrite (Fe3+), show that iron is prevalent as Fe3+, whereas EXAFS data attribute the prevalent Fe3+ to a nanocrystalline phase of ferrihydrite. The dominance of Fe3+ (less soluble than Fe2+) is further confirmed by the fact that previous leaching experiments did not show Fe presence in the solution
As-RICH APATITE FROM MT. CALVARIO: CHARACTERIZATION BY ΜICRO-RAMAN SPECTROSCOPY
No full textIn order to investigate content and localization of arsenic in natural fluorapatite, a micro-Raman spectroscopic study was carried out on As-rich fluorapatite crystals from the volcanic region of Mt. Calvario (Mount Etna, Italy). The crystals, from both the unaltered lavas and the metasomatized rocks, show a pure fluorapatite composition in the core, but an arsenic content of up to 15 wt.% As2O5 in the rim of the crystals from the altered lavas. [AsO4]3- ⇔ [PO4]3- substitutions are proposed on the basis of chemical analysis performed with Electron Microprobe (EMP), Scanning Electron Microscopy (SEM-EDS), and Raman spectroscopy. Micro-Raman investigations carried out on the same crystals studied by EMP show a large band, anomalous for fluorapatite, near 860 cm-1, where chemical microanalyses revealed high contents of As2O5. The Raman broad band near 860 cm-1 is produced by the vibrational modes of [AsO4]3- tetrahedra. No evidence of arsenate phase crystallization was found, therefore it is proposed that [AsO4]3- groups substitute for [PO4]3- groups in the apatite structure. Through μ-Raman spectroscopy, it has been possible to relate the iron content revealed by chemical analysis to magnetite in the fluorapatite from the unaltered lava, and to hematite inclusions in the inner core of the fluorapatite from metasomatized areas
Fluorophlogopite from Biancavilla (Mt. Etna, Sicily, Italy): Crystal structure and crystal chemistry of a new F-dominant analog of phlogopite
No full textFluorophlogopite, a new F-dominant mineral of the mica group, was found at Monte Calvario, Biancavilla, lower southwestern flanks of Mt. Etna volcano (Catania, Sicily, Italy). The mineral occurs in autoclasts of gray-red altered benmoreitic lavas, primarily associated with fluoro-edenite, alkali-feldspars, clino- and ortho-pyroxenes, fluorapatite, hematite, and pseudobrookite. It was formed by metasomatism of the original lava rocks from very hot fluid enriched in F, Cl, and other incompatible elements. Fluorophlogopite occurs as very thin laminae with a diameter of 200 to 400 μm. Main physical properties are pale yellow in color; yellowish-white in thin section; vitreous to resinous luster; transparent; non-fluorescent; Mohs’ hardness 2–3; brittle and malleable; perfect cleavage on {001}; biaxial (–), αcalc = 1.5430(8), β = 1.5682(5), γ = 1.5688(5) (λ = 589 nm); 2Vmeas = 17(2)°; α = acute bisectrix ⊥ (001); nonpleochroic; Dcalc = 2.830 g/cm3 (using empirical formula and single-crystal unit-cell parameters), Dcalc = 2.842 g/cm3 (using empirical formula and powder cell constants). Infrared spectrum did not show a significant absorption band in the OH-stretching region (3800–3600 cm–1) confirming that the F content of the fluorophlogopite from Biancavilla is close to the stoichiometric value. Unit-cell parameters from X-ray powder-diffraction data (114.6 mm diameter Gandolfi camera, CuKα) are a = 5.305(2), b = 9.189(3), c = 10.137(4) Å, β = 100.02(3)°. These data agree with those obtained by single-crystal X-ray studies on a very thin (~15 μm) fluorophlogopite crystal, i.e., Monoclinic (1M polytype); Space Group C2/m; a = 5.3094(4), b = 9.1933(7), c = 10.1437(8) Å, β = 100.062(5)°, V = 487.51(6) Å3, Z = 2. Structure refinements using anisotropic displacement parameters converged at R = 3.50, Rw = 4.37, Rsym = 3.72%. Electron microprobe analysis performed on the same crystal used for X-ray investigation gave: SiO2 = 45.75(39), TiO2 = 1.05(5), Al2O3 = 9.60(19), MgO = 27.92(30), MnO = 0.16(3), FeOtot = 1.25(6), BaO = 0.09(5), K2O = 8.22(11), Na2O = 0.61(30), Cl = 0.02(1) wt%. Secondary Ion Mass Spectrometry (SIMS) was used to estimate light elements [Li2O = 0.30(1) and H2O = 0.16(2) wt%] and fluorine content [F = 8.69(24) wt%]. The new mineral fluorophlogopite and its name were approved by IMA-CNMMN (2006/011)
A comprehensive approach to the investigation of atmospheric particulate PM2.5: preliminary results. 2002
No full textUnderstanding the health effects induced in humans by the inhalation of air particulate
matter requires first that airborne particles be characterized in detail. Aiming at elucidating
some prominent mechanisms and processes involved in the atmospheric environment - human
organism interaction, a comprehensive approach was adopted to thoroughly investigate PM2.5
from a mineralogical, chemical and chemical-physical point of view.
In the present study, two summer and winter samplings collected from the Rome urban area
were investigated by different techniques (SEM-EDS, XRD, ICP-MS, ICP-OES, TGA-DTA).
Mineralogical and physical characterization gave important information on the prevalent
phases (oxides, sulphates, silicates, carbonates, and abundant carbonaceous particles hosting
metals) contained into the material under study. The bulk chemical composition evidenced
the presence of heavy metals, in particular As, Cd, Cu, Cr, Fe, Pb, Ni, and Zn. Consequently,
in order to verify the potential mobility of such heavy metals, batch kinetic leaching tests
were carried out by using a physiological solution mimicking the lung environment and
samples were collected from the solution at different times of treatment. Among the metals contained into the particulate, a leaching trend was observed mainly for Pb, Cd and Cu, with Cd resulting the most mobile metal, whereas no Fe release was observed. The leaching solution mimicking the human intrapulmonary fluid will be exploited for future toxicological tests in cellular models, in order to assess the potentially harmful role of the above metals in biological systems
Content, mineral allocation and leaching behavior of heavy metals in urban PM2.5
Full text linkThis work provides a novel perspective in the field of urban airborne particle investigation that is not currently found in the literature. Four sampling campaigns were performed in the urban area of Rome (Central Italy) during the winter and summer seasons (February and July 2013 and 2014, respectively). The measured concentrations of the regulated 34 elements of As, Cd, Ni and Pb were consistent with those reported by the local Environmental Agency (ARPA Lazio), but non-regulated heavy metals, including Fe, Cu, Cr and Zn, were also
found in PM2.5 and analyzed in detail. As an novelty, heavy metals were associated with the host-identified mineral phases, primarily oxides and alloys, and to a lesser extent, other minerals, such as sulfates, carbonates and silicates. Leaching tests of the collected samples were conducted in a buffered solution mimicking the bodily physiological environment. Despite the highest concentration of heavy metals found during the winter sampling period, all of the elements showed a leaching trend leading to major mobility during the summer period. To explain this result, an interesting comparative analysis between the leaching test behavior and innovative mineral allocation was conducted. Both the heavy metal content and mineral allocation in PM2.5 might contribute to the bioavailability of toxic elements in the pulmonary environment. Hence, for regulatory purposes, the non-linear dependency of heavy metal bioavailability on the total metal content should be taken into account
Toxicity of the readily leachable fraction of urban PM2.5 to human lung epithelial cells. Role of soluble metals
No full textFine airborne particulate matter (PM2.5) has been repeatedly associated with adverse health effects in humans. The PM2.5 soluble fraction, and soluble metals in particular, are thought to cause lung damage. Literature data, however, are not consistent and the role of leachable metals is still under debate. In this study, Winter and Summer urban PM2.5 aqueous extracts, obtained by using a bio-compatible solution and different contact times at 37 °C, were used to investigate cytotoxic effects of PM2.5 in cultured lung epithelial cells (A549) and the role played by the leachable metals Cu, Fe, Zn, Ni, Pb and Cd. Cell viability and migration, as well as intracellular glutathione, extracellular cysteine, cysteinylglycine and homocysteine concentrations, were evaluated in cells challenged with both PM2.5 extracts before and after ultrafiltration and artificial metal ion solutions mimicking the metal composition of the genuine extracts. The thiol oxidative potential was also evaluated by an abiotic test. Results demonstrate that PM2.5 bioactive components were released within minutes of PM2.5 interaction with the leaching solution. Among these are i) low MW (<3 kDa) solutes inducing oxidative stress and ii) high MW and/or water-insoluble compounds largely contributing to thiol oxidation and to increased homocysteine levels in the cell medium. Cu and/or Ni ions likely contributed to the effects of Summer PM2.5 extracts. Nonetheless, the strong bio-reactivity of Winter PM2.5 extracts could not be explained by the presence of the studied metals. A possible role for PM2.5 water-extractable organic components is discussed
Arsenic and fluorine in the Etnean volcanics from Biancavilla, Sicily, Italy: environmental implications
No full textMineralogical and geochemical studies were undertaken in the volcanic area of Biancavilla (Catania, Italy) with the aim of explaining the nature of the high As and F contents of the area's rocks. As and F contents in soils and groundwater were also investigated. The metasomatised benmoreite lavas show fluorine and arsenic concentrations up to about 3,000 and 1,000 mg/kg, respectively. Mineralogical analyses show that fluorine occurs mostly in fluoro-edenite and apatite-(CaF) crystals, both abundantly present in the altered rocks, while As is exclusively attributed to the apatite-(CaF) crystals. Specifically, arsenic was observed only at the borders of these apatite crystals. Leaching tests and sequential extraction procedures were carried out to evaluate the potential remobilisation of As and F by the mineral phases and the eventual risks induced by their spreading. The results of the leaching tests suggest that As is almost totally associated with the 'easily reducible' fraction and that it is released by the preferential dissolution of the arsenic enriched rims of apatite-(CaF) crystals. In soils, As concentration is relatively low (about 15 mg/kg, on average), while F ranges from 236 to 683 mg/kg. The underground waters supplying the town of Biancavilla show As and F contents lower than the allowed limits for drinking water, (As:10 mu g/L, F:1-1.5 mg/L). The limited distribution of these rocks and the relatively limited mobilisation by the minerals both contribute to maintain low As and F values, in soils and groundwaters, despite the high values in metasomatised lava samples
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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