Gabrio Valotto

Source apportionment of PAHs and n-alkanes bound to PM1 collected near the Venice highway

n-Alkanes and polycyclic aromatic hydrocarbons (PAHs) bound to atmospheric particulate matter (PM1) were investigated in a traffic site located in an urban area of Venice Province (Eastern Po Valley, Italy) during the cold season. Considering the critical situation affecting the Veneto Region concerning the atmospheric pollution and the general lack of information on PM1 composition and emission in this area, this experimental study aims at determining the source profile, their relative contributions and the dispersion of finer particles. Four sources were identified and quantified using the Positive Matrix Factorization receptor model: (1) mixed combustions related to the residential activities, (2) agricultural biomass burning in addition to the resuspension of anthropogenic and natural debris carried by the wind, (3) gasoline and (4) diesel traffic-related combustions. The role of local atmospheric circulation was also investigated to identify the pollutant sources.

Multivariate analysis of Ion Beam Induced Luminescence spectra of irradiated silver ion-exchanged silicate glasses.

A multivariate analysis is used for the identification of the spectral features in Ion Beam Induced Luminescence (IBIL) spectra of soda-lime silicate glasses doped with silver by Ag(+)-Na(+) ion exchange. Both Principal Component Analysis and multivariate analysis were used to characterize time-evolving IBIL spectra of Ag-doped glasses, by means of the identification of the number and of the wavelength positions of the main luminescent features and the study of their evolution during irradiation. This method helps to identify the spectral features of the samples spectra, even when partially overlapped or less intense. This analysis procedure does not require additional input such as the number of peaks.

Multivariate analysis as a tool for Ion Beam Induced Luminescence (IBIL) spectra interpretation

Multivariate analysis is used to identify the number and wavelength position of components evolving during irradiation with different rates in Ion Beam Induced Luminescence (IBIL) spectra. The method, based on the study of the eigenvectors of the matrix whose elements are the luminescence intensity values for different wavelengths and fluences, is tested on two different simulated cases and on experimental IBIL spectra collected from a polysiloxane scintillators.

Carbonate and Silicate Abundance Indexing in Coarse-Grained River Sediments Using Diffuse Reflection Infrared Spectroscopy (DRIFTS) and Ion-Beam-Induced Luminescence (IBIL) Spectroscopies

Two different types of spectroscopic methods, namely diffuse reflection infrared spectroscopy (DRIFTS) as a vibrational spectroscopy and ion-beam-induced luminescence (IBIL) as an optical spectroscopy, have been exploited for the analysis of three sand samples collected from the Adige, Bacchiglione, and Brenta rivers (Veneto, Northern Italy) with the aim to set up a procedure for the comparison of the relative abundance of silicates, carbonates, and feldspars. By fitting the spectra, the features corresponding to different geological compounds have been identified and descriptive indexes of their relative amount have been obtained by comparing the peak area ratios.

Ion Beam Induced Luminescence capabilities for the analysis of coarse-grained river sediments

In this work the Ion Beam Induced Luminescence (IBIL) capabilities for the analysis of geological mobile sediment samples from the beds of three major rivers flowing in the Veneto Region (North-Eastern Italy) is presented in the first application of this technique to characterize such samples. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) spectra were also measured and discussed to give indications for the identification of the main luminescence features. The evolution of the different IBIL components with the irradiation dose was studied and their correlation to matrix defects outlined. Finally, a Principal Component Analysis (PCA) of the IBIL evolving spectra was performed to verify the capability of this approach to discriminate among the different samples.

Potentially Harmful Elements in the Atmosphere

The atmosphere represents a complex system influenced by the chemical and physical processes that occur at the Earth surface. These processes include emissions, transport, lifetimes and fates of several anthropogenic and biogenic/geogenic chemicals emitted from a wide variety of sources. Among these chemicals, some are considered air pollutants, i.e. any substance present in ambient air and likely to have harmful effects on human health and/or the environment as a whole. Metals, and in general elements, are natural components of the earth’s crust and constituents of all ecosystems. In the atmosphere, they are mainly related to particle phase but also they can be present in a liquid phase due to the dissolution of aerosol particles in the water drops. Whatever their origin, both natural and anthropogenic, most elements, and in particular heavy metals, are dangerous because they tend to bio-accumulate in the human body.

Fe and Mn speciation in road dust particles by XAS

The speciation of Fe and Mn in road dust particles, collected on the walls and floor of the ventilation shaft of Traforo del San Bernardo highway tunnel, was studied by means of XAS spectroscopy. Absorption spectra were recorded on BM8 at the ESRF (Grenoble, France) at the Fe and Mn K-edges. Several reference compounds were measured along with the samples, and a standard reference material of road dust (BCR723) was also analyzed. Principal Component Analysis (PCA), Least Square Fitting (LSF), analysis of the edge features, and structural refinements (EXAFS), were applied to give complementary information on the speciation, average oxidation state and local structure of Fe and Mn in the collected samples.

Multi-edge X-ray absorption spectroscopy study of road dust samples from a traffic area of Venice using stoichiometric and environmental references

The appropriate selection of representative pure compounds to be used as reference is a crucial step for successful analysis of X-ray absorption near edge spectroscopy (XANES) data, and it is often not a trivial task. This is particularly true when complex environmental matrices are investigated, being their elemental speciation a priori unknown. In this paper, an investigation on the speciation of Cu, Zn, and Sb based on the use of conventional (stoichiometric compounds) and non-conventional (environmental samples or relevant certified materials) references is explored. This method can be useful in when the effectiveness of XANES analysis is limited because of the difficulty in obtaining a set of references sufficiently representative of the investigated samples. Road dust samples collected along the bridge connecting Venice to the mainland were used to show the potentialities and the limits of this approach.

PARAFAC analysis of IBIL spectra from silver ion exchanged glasses

In this work we present for the first time an application of PARAllel FACtor (PARAFAC) analysis to the investigation of Ion Beam Induced Luminescence (IBIL) spectra of Ag+↔Na+ ion exchanged silicate glasses, in order to check the possibility to obtain additional information on the formation of silver aggregates under ion irradiation by a proper statistical rearrangement of experimental spectra. We decomposed the data by PARAFAC taking into account both IBIL emission features and their evolution as a function of the time. Shape and trend under irradiation of the extracted components were correlated to silver concentration and aggregates in the investigated systems. Strength and weakness of this statistical approach applied to IBIL spectra recorded as a function of time were evidenced and discussed.