1,721,199 research outputs found
Caratterizzazione del particolato urbano milanese: risultati preliminari relativi alla frazione carboniosa ed alla distribuzione dimensionale di alcuni metalli
No full textOptimization of an urban particulate matter multi-element analysis method by inductively coupled plasma - Atomic emission spectrometry (ICP-AES)
No full textIn the present work a method for simultaneous metals determination, in urban air particulate matter by ICP-AES has been set up. A large number of elements (18) has been analyzed, including major (Al, Fe, K, and Mg), minor (Na, Ph and Zn) and trace (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Sb, Sr and V) elements. The procedure, consists of microwave sample acidic total digestion by HNO3/HF mixture and subsequent analysis by ICP-AES, using different assemblies depending on sample treatment procedure: a quartz Meinhard nebulizer/cyclonic chamber, if HF excess was eliminated, or a cross-flow nebulizer/plastic Scott chamber, suitable for application with HF. A cyclonic chamber for hydride generation was used for As, Sb and Hg determination. The procedure was tested with Standard Reference Materials 1648 NIST Urban Particulate Matter and Certified Reference Material No8 NIES "Vehicle Exhaust Particulates". Two sampling supports, quartz fibre and polycarbonate filters, have been examined in order to find the most suitable i.e. the one characterized by less interference. Some real samples of urban air particulate matter, TSP, PM10 and PM2.5 fractions, collected during an intercomparison campaign promoted by Regione Lombardia, have been analyzed with the procedure developed
L’importanza litogenetica dei nannofossili calcarei del Triassico Superiore nella sezione di Pizzo Mondello
No full textI nannofossili calcarei (NC) sono parti micrometriche mineralizzate (coccoliti e nannoliti) dell’esoscheletro di alghe coccolitoforidi. Le forme più antiche sono carniche, e nel Triassico Sup. sono riconosciute ~12 specie. I NC acquistano significato lito-genetico nel Giurassico Inf., quindi l’origine della micrite pelagica pre-giurassica é ancora incerta.
La sezione del Triassico Sup. di Pizzo Mondello (M.ti Sicani, Sicilia – Muttoni et al. 2004; Balini et al. 2010), è selezionata per quantificare il reale contributo dei NC alla micrite pelagica, attraverso analisi qualitative e quantitative su 70 sezioni ultrasottili (spessore ~7 μm), usando un microscopio ottico polarizzatore a 1250 ingrandimenti. Le abbondanze assolute sono raccolte contando tutti gli esemplari in 1mm2 di sezione ultrasottile.
Sono identificati otto morfotipi di NC (A, B, C, D, E, F, G, H), tutti nannoliti. Dal punto di vista tassonomico, E corrisponde certamente a P. triassica; F e B a Thoracosphaera; G è assimilabile a P. triassica, ma presenta una crosta esterna probabilmente diagenetica; A è documentato anche da Preto et al. (2012), ma non si riscontrano similitudini con taxa noti. Le altre forme osservate non sono assimilabili a specie note e sono previsti ulteriori studi per chiarirne la posizione. In generale i NC sono più abbondanti nella parte inferiore della sezione (0m-base del “Livello di Breccia”, 146,5m), dove l’abbondanza totale è doppia rispetto alla parte superiore (158m-424,65m). I morfotipi A, C e E sono i più comuni.
Analisi morfometriche su ogni esemplare contato permettono di calcolate l’area (A), volume (V) e le masse (m) di ogni nannolite riconosciuto. A e F sono i più grandi, quindi i più calcificati (A=24835 pg, F=45304 pg); D H e C sono i più piccoli e meno calcificati (D=740 pg, H=795 pg, C=1050 pg). Per quantificare il contributo dei NC alla micrite, sono calcolati i flussi di ogni taxon considerando abbondanze assolute e tasso di sedimentazione. A e F, presentando V, m e abbondanze maggiori, controllano le variazioni delle abbondanze assolute e dei flussi. Le altre tipologie contribuiscono meno alla micrite sia per le piccole dimensioni sia per la scarsa abbondanza. I risultati mostrano che i NC sono litogeneticamente importanti, rappresentando fino al 15% in area della micrite.
Nelle unità litostratigrafiche I e II (Muttoni et al. 2004), abbondanze assolute e flussi sono più alti che nell’unità IV (Muttoni et al. 2004). Considerando la suddivisione dell’unità II in Facies A, B e C (Balini et al. 2010), si nota corrispondenza tra abbondanze, flussi e Facies: valori maggiori corrispondono a Facies C, mentre valori minori corrispondono alle Facies B ed A. L’abbondanza totale qui presentata e quella relativa calcolata da Guaiumi (2010) sono confrontabili e mostrano valori doppi in corrispondenza della Facies C. Poichè l’abbondanza totale dei NC è proporzionale al grado di nodularità, forse abbondanze e flussi sono influenzati dalla condensazione, con dissoluzione preferenziale di coccoliti/nannoliti e della componente più minuta della micrite, concentrando le forme più robuste e resistenti.
I NC nel Triassico Sup. non avevano abbondanze tali da contribuire in modo determinante alla micrite, ma erano già componenti apprezzabili della sedimentazione pelagica.
BIBLIOGRAFIA
Balini M., Bertinelli A., Di Stefano P., Guaiumi C., Levera M., Mazza M., Nicora A., Preto N., Rigo M. (2010). The Late Carnian-Rhaetian succession at Pizzo Mondello (Sicani Mountains). Albertiana 39: 36-57.
Guaiumi C. (2010). Sedimentology of Upper Triassic hemipelagic micrites (Lagonero and Sicani Basins). Tesi di Dottorato. 91 pp., Università di Padova, Scuola di Dottorato di Ricerca in: Scienze della Terra, Ciclo XXI.
Muttoni G., Kent D.V., Olsen P.E., Di Stefano P., Lowrie W. Bernasconi S.M., Hernandez F.M. (2004). Thethyan magnetostratigraphy from Pizzo Mondello (Sicily) and correlation to the Late Triassic Newark astrochronological polarity time scale. GSA Bull. 116: 1034-1058.
Preto N., Rigo M., Agnini C., Bertinelli A., Guaiumi C., Borello S., Westphal H. (2012a). Triassic and Jurassic calcareous nannofossils of the Pizzo Mondello section: a sem study. Iiv. It. Strat. Paleont. 118 (1): 131-141.
Preto N., Willems H., Guaiumi C., Westphal H. (2012b). Onset of significant pelagic carbonate accumulation after the Carnian Pluvial Event (CPE) in the western Tethys. Facies. DOI 10.1007/s10347-012-0338-9
Concentration of PAHs in pine needles : preliminary results of a biomonitoring study in the Milan urban area
No full textIn the present work pine (pinus sylvestris) needles were used as passive samplers for biomonitoring PAHs presence in Milan urban area. Previous studies used this kind of plant for environmental monitoring and showed that the epicuticular waxy layer of pine needles accumulates organic contaminants from surrounding air. In addition conifer leaves are characterized by a long lifetime, thus their study allowed us to work with PAH concentrations integrated over a long period of time, irrespective of atmospheric conditions. In addition pinus sylvestris is widely distributed in the Milan urban area
Technological investigation of luster decorated ancient majolicas
No full textIn this work some luster decorated ancient ceramics have been analyzed in order to acquire knowledge about technological procedures in luster production during the Renaissance period in Italy. Luster is a thin decorative metallic film present on the surfaces of some previously glazed ancient majolicas. It was obtained by applying on the majolica surface a mixture containing silver and copper compounds. Subsequently the object was fired in a reducing atmosphere. It was found that the luster color, red-like or gold-like, depends not only on the chemical composition, determined by Inductively Coupled Plasma Emission Spectroscopy (ICP-OES), but on the dimensions of silver and copper metallic nanoparticles forming the luster too. Nanocrystals' dimensions and structural characteristics were determined by Transmission Electron Microscopy (TEM). As obtaining a satisfactory luster depends on the composition of the underlying glaze too, the chemical composition of the glazes have been determined and the analytical data were submitted to statistical multivariate analysis
The influence of iron content on the promotion of the zircon structure and the optical properties of pink coral pigments
No full textA sol–gel reaction starting from Si and Zr alkoxides, in water-ethanol mixtures, was employed to obtain iron doped zirconium silicate powders
(zircon). The starting amount of the ferric salt in the sol–gel reacting mixture was varied in order to obtain Fe2O3/Zr molar ratios in the range
0.7–10%. The products of the sol–gel reaction were calcined in the range 800–1300 ◦C. X-ray diffractograms, EDX analyses and diffuse
reflectance spectra were obtained and analysed for all the calcined powders; the colour of the pigments was characterised on the grounds of
the CIE (Commission Internationale de l’Eclairage) standard procedure (CIE L∗a∗b∗ measurements). Results from the structural and spectral
characterisations are examined and cross-compared to produce a consistent picture of the role played by iron on the promotion of the zircon
lattice and on the optical properties of the reaction products
Iron doped zirconium silicate prepared by a sol-gel procedure. The effect of the reaction conditions on the structure, morphology and optical properties of the powders
No full textA sol-gel reaction starting from Si and Zr alkoxides, in water-ethanol mixtures, was employed to obtain iron doped zirconium silicate powders (zircon). The speciation of the ferric salt to be added to the starting mixture was varied, the anion matching, in each case, the anionic partner of the acid catalysing the gel polycondensation reaction. The effects of varying the time of the two separate hydrolysis steps leading to the gel formation were investigated. The products of the sol-gel reaction were calcined in the range 800-1300degreesC. The specific surface areas of all the samples were measured by the BET method; X-ray diffractograms and diffuse reflectance spectra were obtained and analysed for all the calcined powders. Results from the structural, morphological and spectral characterisations were examined and compared to produce a consistent picture of the key factors leading to the formation, growth, aggregation and optical properties of the reaction products
A new approach for archaeological ceramics analysis using total reflection X-ray fluorescence spectrometry
No full textThe purpose of this study is to investigate the use of a new quantitative analysis method in case total reflection X-ray fluorescence (TXRF) is applied to archaeological ceramics. This method is alternative to and simpler than traditional TXRF quantitative analysis or typical techniques of elemental analysis such as atomic emission and absorption spectrometry (AES and AAS) which implies the chemical digestion of the sample. A new procedure which allows to obtain an homogeneous sample has been successfully applied. This way it was possible to obtain quantitative results for the elements present in the sedimentation obtained from a suspension prepared with the ceramic sample, by resorting to addition of an internal standard. The archaeological ceramic shards have been also chemically digested and analyzed by inductively coupled plasma-atomic emission spectrometry, AES with flame atomization and electrothermal atomic absorption spectrometry. The quantitative data obtained by means of both TXRF, AAS and AES were compared and worked out by multivariate statistical techniques, such as principal components analysis and hierarchical cluster analysis in order to achieve information concerning pottery provenance
Technological study of ancient ceramics produced in Casteldurante (central Italy) durino Renaissance
No full textIn order to recover the ancient tradition concerning the materials used for the decoration, majolica shards produced during the Renaissance period in Casteldurante, a famous centre for ceramic production in Italy (Marche), have been examined. In the present study, pigments used for the decorations have been investigated by means of inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDX) and diffuse-reflectance UV-Vis spectroscopy. Ochre, lead antimonate yellow, copper-based pigment and smalt have been used as colourants to obtain respectively yellow-orange, yellow, green and blue decorations in accordance with what is reported by the ancient recipes
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