Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
IBIL analysis of road dust samples from San Bernardo tunnel
Graphical abstract
Introduction
Road dust is composed by natural and anthropogenic particles collected on surfaces and along roadsides. This material contributes significantly to atmospheric particulate matter by re-suspension of finer particles [1]. In urban, suburban or industrial centers, it may even represents the dominant source of PM10 (particles with aerodynamic diameter less than 10 μm). Since road dust may contain potentially toxic pollutants such as heavy metals originating from a range of anthropogenic sources, the study of this material is therefore crucial for the choice of pollution reduction policies.
In literature several studies concerning this environmental matrix are reported. In most cases only the elemental composition is probed, for example Apeagyei et al. [2], Fujiwara et al. [3] and Prichard et al. [4] characterized the samples using X-ray fluorescence (XRF), Inductively coupled plasma optical emissions Spectrometry (ICP-OES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), respectively. In other cases road dust samples are analyzed by several techniques in order to identify the potential sources. For instance Gunawardana et al. [5] probed road dust samples by Scanning Electronic Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX) and X-ray Diffraction (XRD) to study the morphology, the elemental and mineral composition, respectively. Instead Bardelli et al. [6] used X-ray Absorption Spectroscopy (XAS), X-ray Diffraction (XRD), Thermo-Gravimetric Analysis (TGA) and SEM–EDS techniques to determine the composition and the speciation of Fe and Mn in road dust samples.
Up to now Ion Beam Induced Luminescence (IBIL) has never been used so far to probe this kind of samples. IBIL is a spectroscopic technique based on the detection of UV, visible and IR radiation emitted by a solid sample excited with an ion beam (H+ or He+) at energy up to a few MeV [7], [8], [9]. The luminescence features in the IBIL spectra depend on the compounds, impurities and defects of the probed samples and on the recombination mechanisms of the excited charge carriers at the emitting centers. Moreover, the high energy density released by the probe induces the luminescence decrease during irradiation due to the damage of the luminescent molecules or to the formation of quenching centers. In some case, the ion-beam promotes the formation of new emitting centers, like defects or radicals, characterized by luminescence features whose intensity initially grows with the fluence [8], [9], [10]. The rate of this change depends on both the incident beam parameters (current density, ion species, and ion energy) and the radiation resistance of the probed material.
Both the luminescence features and the intensity evolution with the irradiation fluence can be used to discriminate the presence of different emitting centers or molecules in the inspected samples. Up to now, IBIL has been extensively used for the analysis of trace elements in geological samples [11], for the study of the defects formation under ion irradiation [9], [10], for the study of the radiation hardness of both inorganic and organic materials [8], [12], [13], [14], [15] and for the discrimination of pigments for cultural heritage [16], [17], [18].
Recently, Valotto et al. [19] developed a method to analyze time evolving IBIL spectra based on the multivariate analysis of a matrix of IBIL spectra collected at fixed time intervals during irradiation. Following this method the main eigenvectors of the covariance matrix of normalized IBIL spectra were studied as a function of the wavelength, allowing to determine the spectral components, evolving with different rate, without any assumption on the number or position of peaks [19].
The aim of this work is to study the effectiveness of IBIL in the analysis of road dust samples, deepening how this technique can get more information on the compounds participating to the formation of the particulate. In particular, road dust from the “Traforo del San Bernardo” tunnel is examined. The spectra collected during irradiation are analyzed by means of a multivariate method in order to identify the main spectral features and an attribution to the luminescence peaks is attempted. The observed components are compared with IBIL spectra collected from possible sources of particulate matter.
Section snippets
Materials and methods
San Bernardo tunnel is located at 30 km from Aosta at the Italian-Swiss border, at about 1900 m above the sea level. Its length is almost 6000 m and it is formed by a single two-lane carriageway with double-way street. Since 2000–2007, the average flux of vehicles has been of 576,000 cars per year and 66,000 truck per year. This is an ideal sampling area to study the particulate emitted from the vehicular traffic, because inside it the road dust: (i) represents the averaged emission from different
Results
Fig. 1 shows normalized IBIL spectra of BCR-723 road dust standard and of four representatives “Traforo del San Bernardo” road dust samples with different particles size (4<63, 4 63-250, A<63, A 63-250). They exhibit a comparable luminescence peak with the maximum located in the 610–620 nm range, a shoulder at about 750 nm, a broad less intense band centered at about 450 nm and a faint feature in the IR part of the spectrum around 850 nm.
Fig. 2 shows four IBIL spectra, acquired after an energy
Discussion
IBIL analysis can be a suitable technique for the analysis of organic and inorganic compounds, owing to the possibility to enlighten the presence of luminescent impurities or compounds, whose spectral features can be used as a signature of the origin of the inspected materials. Moreover, multiparametric analysis of IBIL spectra can give an additional tool for the discrimination of both spectral features and patterns characterizing the probed samples.
In IBIL spectra of road dust samples several
Conclusions
Road dust collect inside the ventilation air shaft of “Traforo del San Bernardo” highway tunnel and some matrices which are the possible sources of particulate matter that constitute it, were analyzed by IBIL spectroscopy. Moreover, it was also analyzed the standard reference material of road dust BCR-723.
All road dust samples of St. Bernardo tunnel and standard BCR-723 exhibit a comparable spectra characterized by an asymmetric luminescence peak with the maximum located in the 610–620 nm range.
References (27)
- et al.
Atmos. Environ.
(2011) - et al.
Ecol. Indic.
(2011) - et al.
Sci. Total Environ.
(2009) - et al.
Chemosphere
(2012) - et al.
Atmos. Environ.
(2011) - et al.
Nucl. Instrum. Methods B
(1997) Nucl. Instrum. Methods B
(2005)- et al.
Nucl. Instrum. Methods B
(2008) - et al.
Nucl. Instrum. Methods B
(1996) - et al.
Nucl. Instrum. Methods B
(2004)
Radiat. Meas.
J. Lumin.
J. Non-Cryst. Solids
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Observation of changes in ion beam induced luminescence spectra from organics during focused microbeam irradiation
2017, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and AtomsCitation Excerpt :Comparing IBIL with organic standards suggests that IBIL from these particulate targets may arise from surface organic contaminants [22]. There are also supporting results of IBIL analysis in which obtained different luminescent properties were obtained from road dust samples [27]. These preliminary experimental results expand the potential application range of IBIL to organic target characterization in complementary conditions for general micro-PIXE analysis; PIXE is assumed to be a non-destructive analysis technique, despite the potential for ion beam impacts to alter the chemical state of targets, particularly in organic compounds.
PARAFAC analysis of IBIL spectra from silver ion exchanged glasses
2017, Spectrochimica Acta - Part A: Molecular and Biomolecular SpectroscopyCitation Excerpt :It is based on the detection of luminescence spectra induced by ion beam irradiation and on the analysis of their changes during irradiation due to the formation and aggregation of point defects. Recently, multivariate statistical methods like Principal Component Analysis (PCA) has been used in order to better exploit the evolution of IBIL spectra during irradiation or the identification of either sample types or luminescence components [22–24]. In particular, a work has been performed demonstrating the capability of PCA applied to IBIL to discriminate silver ion exchanged silicate glasses realized with different treatment conditions [25].
Environmental and traffic-related parameters affecting road dust composition: A multi-technique approach applied to Venice area (Italy)
2015, Atmospheric EnvironmentCitation Excerpt :Most of them are based on the study of the elemental composition (e.g: McKenzie et al., 2008; Amato et al., 2011; Han et al., 2011; Fujiwara et al., 2011b, 2011c; Gunawardana et al., 2012; Huang et al., 2012; Wijaya et al., 2012; Du et al., 2013; Liu et al., 2014; Zhang et al., 2015a), some other on the characterization of the organic compounds (e.g: Omar et al., 2007; Fang et al., 2004; Liu et al., 2007; Hassanien and Abdel-Latif, 2008; Han et al., 2009; Zhang et al., 2015b). X-ray powder diffraction (XRD), X-ray fluorescence (XRF), X-ray absorption spectroscopy (XAS) and Ion Beam Induced Luminescence (IBIL) techniques were also used to study RD samples (e.g: Fujiwara et al., 2011a; Apeagyei et al., 2011; Barrett et al., 2010; Bardelli et al., 2011; Varrica et al., 2013; Sakata et al., 2014; Valotto et al., 2014a); however, the use of a multi-technique approach to characterize this matrix is quite rare. Usually, RD samples are collected to determine the chemical differences among different areas of the same city such as industrial, urban, residential and background (e.g: Liu et al., 2007; Huang et al., 2012; McKenzie et al., 2008; Fujiwara et al., 2011a, 2011b, 2011c; Gunawardana et al., 2012; Du et al., 2013; Kumar et al., 2013b; Hassanien and Abdel-Latif, 2008; Zhang et al., 2015b).
Speciation distribution and risk assessment of heavy metals in typical material roof dusts
2015, Huanjing Kexue/Environmental Science