[Show abstract][Hide abstract] ABSTRACT: On a global scale, mineral dust is one of the major components of atmospheric aerosols and has important effects on the radiative budget of the atmosphere and thus on climate forcing. An accurate measurement of the concentration of crustal elements, namely Na, Mg, Al, Si, K, Ca, Ti, and Fe, is mandatory for the study of desert aerosols. The concentration of light elements, when measured by X-ray emission techniques such as X-ray fluorescence (XRF) and particle-induced X-ray emission (PIXE), can be underestimated owing to self-absorption of the emitted soft X-rays inside aerosol particles. In this work, we analyzed dust samples collected in field campaigns and samples produced in the laboratory using dust of known composition. Measurements have been conducted with PIXE and energy-dispersive XRF (ED-XRF), together with an attenuation-free technique such as particle-induced gamma-ray emission (PIGE) and attenuation corrected wavelength-dispersive XRF (WD-XRF) by internal standard calibration. We focus on the determination of Al and present results of a PIXE versus PIGE intercomparison. Aluminum concentration was measured with both techniques in dust samples collected by aircraft sampling over western Africa during winter 2006 and summer 2007. An underestimation of the Al concentration determined by PIXE was observed (up to 40%), and it was compared with the results of a simple calculation using basic physics and the size distribution of the collected aerosol. Similar attenuation was observed for Mg, Al, and Si in the laboratory samples analyzed by ED-XRF and WD-XRF. In order to use concentration ratios involving light elements as tracers of the region of emission of the sampled dust, these artifacts (i.e., underestimation of the concentration of light elements) induced by self-attenuation should be properly considered and corrected.
Journal of Geophysical Research Atmospheres 01/2010; 115(D1). DOI:10.1029/2009JD012701 · 3.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The results from a study carried out in the urban area of Genoa, Italy, where a large steel smelter recently shut down are presented. We had the opportunity to sample particulate matter (PM) before and after plant closure and, therefore, to measure the changes in concentration and composition of PM10 (atmospheric PM with aerodynamic diameter <10 microm). Elemental concentrations of Na to Pb were obtained through energy dispersive X-ray fluorescence (ED-XRF), and the contributions of specific sources of PM10 were calculated by positive matrix factorization (PMF). The PM10 average concentration turned out to be surprisingly similar before and after closing of the smelter. Nevertheless, the comparison among data collected in the two periods (plant operating and closed), even with the limited information provided by ED-XRF, allowed us to single out two sources of PM related to the smelter activities, to extract their emission profile, and to quantify the impact of the plant on PM10 levels.
Journal of the Air & Waste Management Association (1995) 06/2009; 59(5):514-9. DOI:10.3155/1047-32188.8.131.524 · 1.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aerosols posses a substantial influence over the development and alteration of climate dynamics on the Caribbean. Among the principal sources of particulate matter that influence this region are the North African desert area, from which dust particles are usually transported by the trade winds, and anthropogenic activities that involve the combustion of fossil fuel. These types of aerosols have the potential to alter forests, among other multiple environments. This study focuses on the effects this type of aerosols can exert on Guánica's Dry Forest (GDF) in Puerto Rico. The GDF is one of the most intact mature dry forests in the Caribbean, is a place that has been chosen as the Atlantic Neotropical core site in the National Ecological Observatory Network (NEON), and is an UNESCO Man and Biosphere Reserve. To chemically characterize the aerosol inputs to the GDF, aerosol samples were collected using Stacked-Filter Units. Samples were analyzed using a thermal-optical analyzer (EC/OC analyzer) to determine the concentrations of organic and elemental carbon. X-ray Fluorescence (XRF) and Inductively coupled plasma (ICP) were also used to determine the elemental concentrations of different ions species. Preliminary ICP results showed the presence of Al, Na, Mg, Fe, and Ca in higher concentrations in the coarse than in the fine fraction, suggesting the influence of mineral dust. This was confirmed by back trajectory analyses using the NOAA HYSPLIT model. The EC/OC analyses showed low organic carbon concentrations during African dust events, which was expected since African dust particles are mainly inorganic. Elemental Carbon concentrations were also very low, showing that the study site had little anthropogenic influence. Results related to the elemental composition as determined using XRF and ICP analyses will also be presented at the meeting.
[Show abstract][Hide abstract] ABSTRACT: Ion Beam Analysis (IBA) techniques are a powerful tool to study atmospheric aerosol composition, since they are quantitative, multi-elemental, fast, high-sensitivity and non-destructive analytical methods. At the 3 MV Tandetron accelerator of the LABEC laboratory of INFN in Florence an external beam facility is fully dedicated to measurements of elemental composition of atmospheric aerosols. All the elements with Z>10 are simultaneously detectable by Particle Induced X-ray Emission (PIXE) in few minutes of beam time, including several important tracers of peculiar aerosol sources and potentially harmful elements, with minimum detection limits ranging between 1 and 10 ng/m3. Light elements (H, C, N, O), which are the main aerosol constituents, can be detected by means of in-vacuum Particle Elastic Scattering Analysis (PESA). The application of both PIXE and PESA allows a complete mass reconstruction of aerosol samples. Since these methods are non-destructive, it is possible to apply complementary techniques, like Ion Chromatography, on the same samples, obtaining information, for example, on the chemical composition. Scanning possibility may also be very useful, allowing time trend reconstruction by the analysis of time-sequence aerosol deposits collected by continuous samplers. Using a two-stage ``streaker'' sampler the concentration time series of all the elements with Z>10 can be measured with hourly resolution. In this paper the peculiarity of these methods will be highlighted and the results of recent campaigns will be shown, including the application of IBA techniques to aerosol daily and hourly samples, collected in urban and industrial areas.
[Show abstract][Hide abstract] ABSTRACT: Daily time series measurements of elements or compounds are widely used to apportion the contribution of specific sources of particulate matter concentration in the atmosphere. We present results obtained for the urban area of Genoa (Italy) based on several hundred of PM10, PM2.5 and PM1 daily samples collected in sites with different geo-morphological and urbanization characteristics. Elemental concentrations of Na to Pb were obtained through Energy Dispersive X-Ray Fluorescence (ED-XRF), and the contributions of specific sources of particulate matter (PM) concentration were apportioned through Positive Matrix Factorization (PMF). By sampling at different sites we were able to obtain, in each PM fraction, the average and stable values for the tracers of specific sources, in particular traffic (Cu, Zn, Pb) and heavy oil combustion (V, Ni). We could also identify and quote the contamination of anthropogenic PM in "natural" sources (sea, soil dust). Sampling at several sites in the same urban area allowed us to resolve local characteristics as well as to quote average values.
Science of The Total Environment 09/2008; 401(1-3):81-9. DOI:10.1016/j.scitotenv.2008.03.008 · 4.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The impact of big harbours on the air quality is in important issue both from the environmental and the economical point of view. The harbour of Genoa is the largest in Italy and one of the major ports of the Mediterranean. We have determined the fraction of Particulate Matter (PM) concentration in town due to the heavy oil combustion of the diesel engines of the vessels in the harbour. This turned out to be 12% in PM10 and 25% in PM2.5 and PM1, with about 85% of the PM from this source concentrated in particles with aerodynamic diameter, D(ac) < 1 mu m. We could also point out a link between concentration peaks of the tracers of heavy oil combustion (V and Ni) and the ferryboats traffic. The key toot in this work was the coupling between particular sampling devices and some Ion Beam Analysis (IBA) techniques, in particular Particle Induced X-ray Emission (PIXE), which belong to the broader category of nuclear techniques in applied physics.
Il Nuovo Cimento C 07/2008; 31(4):527-536. DOI:10.1393/ncc/i2008-10306-5
[Show abstract][Hide abstract] ABSTRACT: Nowadays, high-time resolved aerosol studies are mandatory to better understand atmospheric processes, such as formation, removal, transport, deposition or chemical reactions. This work focuses on PM10 physical and chemical characterisation with high-time resolution: elements (from Na to Pb), ions and OC/EC fractions concentration were determined during two weeks in summer and two in winter 2006 with 4-hours resolution. Further measurements aimed at hourly elemental characterisation of fine and coarse fractions and at the determination of particles number concentration in the 0.25-32 microm size range in 31 bins. The chemical mass closure was carried out in both seasons, enhancing intra-day differences in PM10 composition. In Milan, the highest contribution came from organic matter (34% and 33% in summer and winter, respectively); other important contributors were secondary inorganic compounds (16% and 24% in summer and winter, respectively) and, in summer, crustal matter (14%). Temporal trends showed strong variations in PM10 composition during contiguous time-slots and diurnal variations in different components contribution were identified. Moreover, peculiar phenomena, which would have hardly been detected with 24-hours samplings, were evidenced. Particles removal due to precipitations, aerosol local production and long range transport were studied in detail.
[Show abstract][Hide abstract] ABSTRACT: PIXE and XRF are very effective techniques in atmospheric aerosol investigation, therefore they are extensively used by the authors. In this work an inter-laboratory comparison of the results obtained analysing several samples (collected on different substrata) with both techniques is presented: the samples were analysed by PIXE (in Florence, at the 3MV Tandetron accelerator of LABEC laboratory) and by XRF (in Genoa and Milan, where two Oxford XRF instruments are operational). The results of the three sets of measurements are in good agreement for all the analysed samples.The aim of this work was also to compare PIXE and XRF performance in atmospheric aerosol analysis with the routine set-up currently in use at the three laboratories, to determine the best technique to be applied depending on the substratum used for aerosol sampling and the main elements of interest for each specific research project. Results of the comparison between the minimum detection limits of both techniques will be shown for all the measured elements, for different substrata (Teflon, polycarbonate and cellulose mixed esters).
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 05/2008; 266(10):2401-2404. DOI:10.1016/j.nimb.2008.03.056 · 1.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The capelin, Mallotus villosus (Osmeriformes, Osmeridae), is an ecological and commercial key component of the sub-arctic ichthyofauna. Here, we provide the first cytogenetic information on the species based on both conventional karyotyping and chromosomal mapping of 45S and 5S ribosomal genes through fluorescence in situ hybridization (FISH). The capelin genome displayed a diploid number of 54 with the karyotypic formula 26m/sm+28st/a and a fundamental number = 80. Both classes of ribosomal genes appeared to be spread at multiple chromosomal locations, i.e. the 45S and 5S rDNA clusters were detected on six and seven chromosome pairs, respectively. A linked chromosomal organization of the major and minor ribosomal genes classes has been visualized in most of the rDNAs chromosomal locations. A comparative analysis of the available cytogenetic data for the family Osmeridae reveals diploid numbers higher than 48 and high fundamental numbers. This suggests that a rearranged karyotype is a shared feature within this family.
[Show abstract][Hide abstract] ABSTRACT: The Falkland’s mullet, Eleginops maclovinus, is the only modern representative of the Sub-Antarctic family Eleginopidae, suborder Notothenioidei. Based on specimens from the Falkland Islands/Islas Malvinas, the Magellan Straits, and the southern coast of Chile, we have established the specific karyotype by conventional cytogenetic methods and have mapped the chromosomal loci of the ribosomal genes by fluorescence in situ hybridization (FISH). With respect to the basal notothenioid family Bovichtidae and to the hypothetical basal condition of the suborder (diploid number = 48, fundamental number = 48), E. maclovinus displays a slightly derived karyotype (diploid number = 48, fundamental number = 54). In contrast to the bovichtids, the 45S and 5S ribosomal DNAs are co-localized to a single chromosome pair. Condensation of the ribosomal genes to a single locus is likely to represent an intermediate stage in the evolution of notothenioid karyology. Features unique to E. maclovinus (e.g., morphology of its large, rDNA-bearing chromosome pair) probably result from divergence during the long evolutionary isolation of the family.
[Show abstract][Hide abstract] ABSTRACT: Sub-micron sized particles are of increasing concern owing to their effects on human health and on the environment. Up to now there are still very few studies on PM1 (i.e. particulate matter with aerodynamic diameter smaller than 1 μm) chemical characterisation; the sub-micron sized fraction is not under regulations although it is of interest because it is almost exclusively associated to anthropogenic sources. To perform the first large-scale assessment of sub-micron sized aerosol concentrations, composition and sources, two monitoring campaigns at three urban sites in Italy were carried out during the wintertime and summertime of 2004.Chemical characterisation (elements, soluble ionic fraction, elemental and organic carbon) was carried out on PM1 samples: major contributions were due to organic matter (about 30% in summer and 50% in winter) and ammonium sulphate (about 10% in winter and 40% in summer). During the cold season, nitrates also contributed up to 30% in Milan (lower contributions were registered at the other two urban sites). Chemical mass closure was achieved with an unaccounted mass in the range 14–22%. Positive Matrix Factorisation (PMF) was applied to identify the major sub-micron sized particles’ sources.
[Show abstract][Hide abstract] ABSTRACT: We describe a new experimental methodology based on the contemporary use of two-stage continuous streaker samplers and optical particle counters. This is a complementary approach to size-segregated particulate matter (PM) sampling, and it is able to give information on the elemental size distribution and to assess the contribution of major PM source to size bins. PM samples in the fine and coarse fraction of PM10 have been collected by a two-stage streaker sampler and analyzed by particle-induced X-ray emission (PIXE) to obtain elemental concentration time series with hourly resolution. PM sources and profiles were singled out by positive matrix factorization (PMF). A multi-linear regression of size-segregated number of particles versus the sources, resolved by PMF, made possible the apportionment of size-segregated particles number in a fast and direct way. Results obtained in three sampling sites, located in different urban districts are discussed.
[Show abstract][Hide abstract] ABSTRACT: Atmospheric aerosols in the PM(10) fraction have been simultaneously sampled at three sites in the Genoa urban and suburban area during the second half of 2005, and information on the elemental composition has been gathered through energy dispersive X-ray fluorescence. Thanks to the simultaneous measurements and wind information, a few aerosol transport and transformation processes originated from the nearby sea and in the neighbouring Po Valley have been described. Sea salt concentrations at the three sites were well correlated and often related to Southern sector winds; moreover, by examining the Cl/Na ratio at two sites the time scale for Cl depletion in particulate matter has been estimated as 1-1.5 h for the Genoa atmosphere. During a Northerly gale, excess elemental Si concentrations (peaking more than 4 mug m(-3)) were found at two sites, and were ascribed to an unknown local source. Finally, during an 11-day long 'heat wave' large concentrations for total PM(10), dust and secondary compounds have been found; these large concentrations lead to a number of exceedances of air quality standards, and have been ascribed to advection from the Po Valley.
Science of The Total Environment 06/2007; 377(2-3):396-406. DOI:10.1016/j.scitotenv.2007.02.024 · 4.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The chromosomal location of the IgH locus has been analyzed in several bony fish of the Antarctic perciform group Notothenioidei. Two IgH probes were prepared from the species Trematomus bernacchii (family Nototheniidae, tribe Trematominae) and mapped onto the chromosomes of ten species belonging to the same genus (Trematomus) and in two outgroups, through one-color and two-color FISH. A single location of the IgH locus was found in the majority of the species examined, including the outgroups, whereas in four of them the IgH genes splited to two chromosomal loci. RT-PCR experiments revealed the presence of three allelic sequences in T. newnesi, a species in which the IgH genes were organized in two chromosomal loci. Possible pathways leading to IgH genes duplication during the diversification of trematomine fishes were inferred from the analysis of the FISH patterns in a phylogenetic context. The present work provides the first comprehensive picture of IgH genes organization at chromosomal level in a bony fish group.
[Show abstract][Hide abstract] ABSTRACT: The two giant notothenioid species, the Patagonian toothfish Dissostichus eleginoides and the Antarctic toothfish D. mawsoni are important components of the Antarctic ichthyofauna and heavily exploited commercially. They have similar appearance and size, both are piscivorous and bentho-pelagic, but differ in their geographic distribution and absence/presence of the antifreeze trait. We karyotyped these two sister species by analyzing specimens collected from multiple Antarctic and sub-Antarctic sites. Both species have a diploid number of 48, but differ in karyotypic formula, (2m+2sm+44a) for D. eleginoides and (2m+4sm+42a) for D. mawsoni, due to an extra pair of submetacentric chromosomes in the latter. Chromosomal fluorescence in situ hybridization with rDNA probes revealed unexpected species-specific organization of rRNA genes; D. mawsoni possesses two rDNA loci (versus one locus in D. eleginoides), with the second locus mapping to its additional submetacentric chromosome. The additional rRNA genes in D. mawsoni may be a cold-adaptive compensatory mechanism for growth and development of this large species in freezing seawater.
[Show abstract][Hide abstract] ABSTRACT: Atmospheric aerosols in the PM10 and PM1 fractions have been sampled at the Global Atmospheric Watch station Mount Cimone, Italy (2165 m above mean sea level) for 3 months during summer 2004, and simultaneous size distributions have been derived by means of an optical particle counter. Samples have been analyzed by X-ray fluorescence, ion chromatography, and thermal-optical methodology in order to quantify their elemental, ionic, and carbonaceous constituents. The concentration of PM10 was 16.1 +/- 9.8 mug m-3 (average and standard deviation). Source apportionment allowed us to identify, quantify and characterize the following aerosol classes: anthropogenic pollution (10 mug m-3), mineral dust (4 mug m-3), and sea salt (0.2 mug m-3). Pollution has been further split into ammonium sulfate (44%), organic matter (42%), and other compounds (14%). The nitrate/sulfate ratio in the polluted aerosol was 0.1. Fine particles have been completely related to the polluted aerosol component, and they represented 70% in weight of pollution. Coarse particles characterized the dust and salt components, and crustal oxides have been found to be the largest responsible for the aerosol concentration variations that occurred during the campaign. Nitrate has also been found in the coarse particles, representing ~10% of mineral dust. The analysis of the transport mechanisms responsible for aerosol fluctuations permitted us to identify the origin of the major aerosol components: Pollution has been ascribed to regional transport driven by boundary layer meteorology, whereas mineral dust has been related to long-range transport events originating in the Sahara and Sahel. A particularly significant Saharan episode has been identified on 10 August 2004 (PM10 daily concentration, 69.9 mug m-3). Average elemental ratios for the African dust events were as follows: Si/Al = 2.31, Fe/Ca = 0.94, Ca/Al = 0.90, K/Ca = 0.44, Ti/Ca = 0.11, and Ti/Fe = 0.12.
Journal of Geophysical Research Atmospheres 12/2006; 111(D24). DOI:10.1029/2006JD007145 · 3.43 Impact Factor