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It is estimated that nowadays about 30% of items which appear on the art market are forgeries. To combat this traffic, the opinion of qualified experts in artwork authentication needs the support of scientific methods providing concrete facts and evidence. Many aspects can be addressed using different investigation techniques such as materials characterisation, absolute age determination, alteration phenomena, etc. Most challenging is the domain of paintings authentication owing to the complexity and diversity of the materials (paint layers, ground, varnish, canvas, etc.) and the preferable use of non-destructive methods. Routine techniques for this task are Vis, UV, IR and X-ray imaging, optical and electron microscopies, XRD, FTIR, HPLC and GC-MS, micro- and macro- XRF. In the present work we report on analysis of a painting obtained by new and emerging Nuclear Techniques (NT) of potential interest in the forensic investigation of paintings and other cultural heritage objects. The work was carried out in the framework of the IAEA Coordinated Research Project F11021: Enhancing Nuclear Analytical Techniques to Meet the Needs of Forensic Sciences. An ancient painting of unknown author and title, considered by art experts from its style as a French school composition of the 17th-18th centuries, was acquired at an auction for this study. Paint coupons of 2 cm x 1 cm were sampled in the sky on the right border of the painting and distributed to the participants for the application of the new NTs, rather than circulating the object. The objective was to evaluate their ability to determine the painting authenticity and to point out possible restorations or anachronic features. Following NT were applied to analyse paint coupons by different labs: direct 14C AMS dating of binder, canvas and support, Secondary Ion Mass Spectrometry with MeV ions (MeV-SIMS) of binder and pigments, full-field PIXE mapping of pigments, differential PIXE and total IBA for the determination of paint layer sequence and composition including pigment/binder ratio. Although not belonging to NT, potential of Optical Photothermal Infrared Spectroscopy (O-PTIR) imaging was also exploited. Results obtained by different techniques are presented and discussed. It is shown that the combination of above-mentioned techniques allowed to trace back the history of the test painting.

Trabajo presentado a la 16th International Conference on Particle Induced X-ray Emission (PIXE), celebrada en Caldas da Rainha (Portugal) del 24 al 29 de marzo de 2019.

Trabajo presentado al EcoDesert International Symposium, celebrado en Almeria (España) del 20 al 22 de febrero e 2019., Every year, 1500-2000 Tg of dust are emitted from soil to the atmosphere. The resulting aerosol dust particles have a size ranging from sub-1 μm to tens of microns, and a lifetime from hours to two weeks. Aerosol dust impacts on climate and on biogeochemical cycles, and is involved in the Earth System. About 50 to 70% of global dust emissions occur in North Africa. Most of dust exports to the Atlantic occur in the so-called Saharan Air Layer, a warm, dry and dusty high-altitude air stream that reaches the Americas. At the Izaña Observatory, 2400 m.a.s.l. in Tenerife (Spain), we studied (i) the variability of dust composition in the Saharan Air Layer, (ii) the North African sources and (iii) the large-scale meteorology prompting the variability observed. For this purpose, we performed (i) one-hour resolution sampling of aerosols, followed by (ii) PIXE (Particle bombing Induced X Ray Emission) analysis, and (iii) further data interpretation with meteorological tools and satellite observations. During one-week dust events, we found that the ratios of some elements (e.g. Ca, Mg or K, among others) to Al (soil tracer) changed by a factor of about 2 in a few (5-7) hours. This high variability in dust points to a concatenation of the sources contributing to dust over the North Atlantic. By back-trajectory analysis, Median Ratios At Receptor plots and MODIS and MSG – SEVIRI satellite observations, we observed that the sources activated during the study period were located in topographical lows located in three main regions: NE Algeria – Tunisia (dust rich in Ca, Sr, Mg and K), W Algeria-E Morocco (Na and Cl) and N Mali-S Algeria (rich in Si and Fe). In a six-day period, there were seven concatenated impacts from the sources identified, which were traced by the variability in the ratios of the different elements to Al. These results provide a new and more complex view of the dust exported to the Atlantic, compared to the simplistic approach based on bulk-dust measurements and modelling. These results have implications of the impact and influence of dust on climate.

The Mediterranean Basin atmosphere is influenced by both strong natural and anthropogenic aerosol emissions and is also subject to important climatic forcings. Several programs have addressed the study of the Mediterranean basin; nevertheless important pieces of information are still missing. In this framework, PM10 samples were collected on a daily basis on the island of Lampedusa (35.5° N, 12.6° E; 45 m a.s.l.), which is far from continental pollution sources (the nearest coast, in Tunisia, is more than 100 km away). After mass gravimetric measurements, different portions of the samples were analyzed to determine the ionic content by ion chromatography (IC), the soluble metals by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the total (soluble + insoluble) elemental composition by particle-induced x-ray emission (PIXE). Data from 2007 and 2008 are used in this study. The Positive Matrix Factorization (PMF) model was applied to the 2-year long data set of PM10 mass concentration and chemical composition to assess the aerosol sources affecting the central Mediterranean basin. Seven sources were resolved: sea salt, mineral dust, biogenic emissions, primary particulate ship emissions, secondary sulfate, secondary nitrate, and combustion emissions. Source contributions to the total PM10 mass were estimated to be about 40 % for sea salt, around 25 % for mineral dust, 10 % each for secondary nitrate and secondary sulfate, and 5 % each for primary particulate ship emissions, biogenic emissions, and combustion emissions. Large variations in absolute and relative contributions are found and appear to depend on the season and on transport episodes. In addition, the secondary sulfate due to ship emissions was estimated and found to contribute by about one-third to the total sulfate mass. Results for the sea-salt and mineral dust sources were compared with estimates of the same contributions obtained from independent approaches, leading to an estimate of the water content bound to the sea salt in the marine source.

This study aims to determine the mineral contribution to PM10 in the central Mediterranean Sea, based on 7 yr of daily PM10 samplings made on the island of Lampedusa (35.5° N, 12.6° E). The chemical composition of the PM10 samples was determined by ion chromatography for the main ions, and, on selected samples, by particle-induced X-ray emission (PIXE) for the total content of crustal markers. Aerosol optical depth measurements were carried out in parallel to the PM10 sampling. The average PM10 concentration at Lampedusa over the period June 2004–December 2010 is 31.5 μg m−3, with low interannual variability. The annual means are below the EU annual standard for PM10, but 9.9% of the total number of daily data exceeds the daily threshold value established by the European Commission for PM (50 μg m−3, European Community, EC/30/1999). The Saharan dust contribution to PM10 was derived by calculating the contribution of Al, Si, Fe, Ti, non-sea-salt (nss) Ca, nssNa, and nssK oxides in samples in which PIXE data were available. Cases in which crustal content exceeded the 75th percentile of the crustal oxide content distribution were identified as elevated dust events. Using this threshold, we obtained 175 events. Fifty-five elevated dust events (31.6%) displayed PM10 higher than 50 μg m−3, with dust contributing by 33% on average. The crustal contribution to PM10 has an annual average value of 5.42 μg m−3, and reaches a value as high as 67.9 μg m−3 (corresponding to 49% of PM10) during an intense Saharan dust event. The crustal content estimated from a single tracer, such as Al or Ca, is in good agreement with the one calculated as the sum of the metal oxides. Conversely, larger crustal contents are derived by applying the EU guidelines for demonstration and subtraction of exceedances in PM10 levels due to high background of natural aerosol. The crustal aerosol amount and contribution to PM10 showed a very small seasonal dependence; conversely, the dust columnar burden displays an evident annual cycle, with a strong summer maximum (monthly average aerosol optical depth at 500 nm up to 0.28 in June–August). We found that 71.3% of the dust events identified from optical properties over the atmospheric column display a high dust content at the ground level. Conversely, the remaining 28.7% of cases present a negligible or small impact on the surface aerosol composition due to the transport processes over the Mediterranean Sea, where dust frequently travels above the marine boundary layer, especially in summer. Based on backward trajectories, two regions, one in Algeria–Tunisia, and one in Libya, are identified as main source areas for intense dust episodes occurring mainly in autumn and winter. Data on the bulk composition of mineral aerosol arising from these two source areas are scarce; results on characteristic ratios between elements show somewhat higher values of Ca / Al and (Ca + Mg) / Fe (2.5 ± 1.0, and 4.7 ± 2.0, respectively) for Algeria–Tunisia than for Libyan origin (Ca / Al = 1.9 ± 0.7 and (Ca + Mg) / Fe = 3.3 ± 1.1).

A set of PM2.5 samples (n= 121) collected at an urban background location in Elche (in southeastern Spain) from December 2004 to November 2005 was analysed by particle-induced X-ray emission (PIXE) and ion chromatography in order to provide source identification and potential source locations. Positive matrix factorization (PMF) was used to estimate source profiles and their mass contributions. The PMF modelling identified six sources: aged sea salt (9.2%), ammonium sulphate (40.4%), soil dust related to Saharan outbreaks (13.0%), traffic 1 (18.9%), nitrate aerosol and traffic 2 (5.5%) and local soil dust (6.0%). Potential source contribution function (PSCF) was then used to identify potential source locations. Scarce influence from Mediterranean and European regions was found with the exception of the nitrate source, whose potential source areas were northern Italy and eastern France. Primary source regions for the remaining components (ammonium sulphate, soil dust-related to Saharan outbreaks and aged sea salt) with known mass contributions due to long-range transport have a marked Atlantic and North African location, primarily between Morocco and northwestern Algeria.DOI: 10.1111/j.1600-0889.2010.00510.x