Content, mineral allocation and leaching behavior of heavy metals in urban PM2.5

This 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

Environmental concentrations of fibers with fluoro-edenitic composition and population exposure in Biancavilla (Sicily, Italy)

Introduction. The town of Biancavilla (Sicily) was included in the National Priorities List of Contaminated Sites due to environmental dispersion of amphibole fibers owing to the extraction of materials from a local quarry. The present report summarizes results from several, hitherto unpublished, environmental surveys carried out in the area, as well as from published analyses of the chemistry and composition of fibers.Methods. Data included here comprises environmental fiber concentrations by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) analysis in soil, indoor and outdoor air, personal monitoring, as well as a chemical characterization of the fibers.The full chemical structure and spectroscopic characterization of fibers were obtained through a multi-analytical approach: SEM-EDS, X-ray powder diffraction (XRPD), as well as Mössbauer (MS) and Fourier transform infrared (FT-IR) spectroscopies.Results. Data analyzed provided a spatial and temporal picture of fiber concentrations in Biancavilla, and a qualitative assessment of population exposure. Results suggest that until 2000, the population had been exposed to high levels of amphibole fibers. Mitigation measures adopted since 2001, gradually reduced exposure levels to about 0.1-0.4 ff/l. Previous studies on fibrous amphiboles from Biancavilla reported considerable chemical variability. Differences in composition, especially concerning the presence of Si, Ca, Fe, and Na, were found both within and between samples. Compared to the previously investigated prismatic fluoro-edenite, these fibrous fluorine amphiboles consistently showed higher average values of Si and Fe content, whereas Ca was significantly lower, which we consider a distinctive characteristic of the fluorine fibrous variety.Conclusions. The population of Biancavilla had been highly exposed to a suite of fibrous amphiboles for over 50 years. Dust mitigation measures have gradually reduced exposure, but continuous environmental follow-up is necessary in order to monitor exposurelevels and prevent adverse health effects for future generations

Halogen-dominant mineralization at Mt. Calvario dome (Mt. Etna) as a response of volatile flushing into the magma plumbing system

The exceptional occurrence of fluorine-rich mineral phases in the benmoreitic lava dome of Mt. Calvario (south-western flank of Mt. Etna) has given the opportunity to understand the genetic process allowing their crystallization. Both primary and secondary mineral associations were found, namely: plagioclase, clinopyroxene, olivine, fluorapatite and iron oxides as primary assemblage, whereas fluoro-edenite and fluorophlogopite, ferroan-enstatite, hematite, pseudobrookite and tridymite as secondary mineralization. In addition to some major and trace elements (e.g., Fe, Ti, Na, K, P, Ba, Rb, Sm, Zr), particularly fluorine and chlorine concentrations of the whole rock are significantly higher than other Etnean prehistoric benmoreites, and cannot be accounted for common differentiation processes in the feeding system. The selective enrichment in some elements has been here attributed to volatile flushing occurring in the plumbing system, with fluid/melt ratio of 0.65:1. The resulting high amount of fluorine, coupled with its high solubility even at low pressure for benmoreitic melts, finally led to nucleation and growth of F-rich mineral phases during syn- and post-eruptive conditions

Local order and valence state of Fe in urban suspended particulate matter

X-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

Fluorophlogopite from Biancavilla (Mt. Etna, Sicily, Italy): Crystal structure and crystal chemistry of a new F-dominant analog of phlogopite

Fluorophlogopite, 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)

As-RICH APATITE FROM MT. CALVARIO: CHARACTERIZATION BY ΜICRO-RAMAN SPECTROSCOPY

In 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

A comprehensive approach to the investigation of atmospheric particulate PM2.5: preliminary results

Understanding 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