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Abstract Air pollution events at urban locations are driven by both emissions and atmospheric dispersion conditions. Atmospheric dispersion is not routinely assessed at monitoring networks thus preventing the possibility of understanding if high pollution events are due to increasing emissions or to the occurrence of atmospheric stability conditions. In principle, this piece of information would be very useful to implement effective strategies for pollution abatement. In this work, an 18-year long dataset of radon (222Rn) progeny measurements was used to estimate equivalent mixing layer heights (hereafter referred to as MH) with hourly resolution by means of a box model. Mean MH obtained by more conventional modelling approaches based on turbulence variables on a 5-year long dataset agreed very well with results obtained by the box model. It is noteworthy that in the literature there are scarce MH data for such long periods and comparisons between estimates by radioactive tracers and other approaches are often limited to a few days/weeks. Results suggested that relatively simple methods like the one here proposed could be implemented at pollution monitoring stations in order to improve available information and better understand the evolution of pollution events on 1-h timescale. In addition, the long-term assessment here presented provides useful data to pursue MH climatological studies. Graphical abstract Image 1 Highlights • Radon and its progeny are good markers for atmospheric dispersion conditions. • Short-lived radon decay products measured for 18 years with 30 min resolution. • A box model based on radon concentrations estimated equivalent mixing layer heights. • Radon-based and turbulence-based estimates for MH resulted comparable. • Radon measurements at monitoring stations could be effectively implemented. [ABSTRACT FROM AUTHOR]

Abstract: In this work, light-absorption measurements were carried out on quartz-fibre and PTFE (i.e. Teflon®) filters using a home-made polar photometer in order to assess the role of organic sampling artefacts on optical measurements. Filter-based light-absorption instruments are generally operated with quartz/glass-fibre filter tapes and – as far as we know – currently there are no systematic studies on the sampling artefacts affecting the light absorption coefficient measurements. In this work, particulate matter (PM) samples were collected in Milan (Italy) during different sampling campaigns with the aim of (1) validating the polar photometer; (2) comparing the absorption properties measured on PM collected on different filter media; (3) investigating the causes of the observed differences. The polar photometer was demonstrated to give aerosol light absorption coefficients (σ ap in Mm−1) fully comparable to those obtained by a Multi-Angle Absorption Photometer (MAAP) when using quartz-fibre filters to collect atmospheric particles. The aerosol light absorption coefficients determined on samples collected in parallel on quartz-fibre and PTFE filters showed significant differences (about 40%). These differences were much lower (i.e. 8%) when the quartz-fibre filter sampling line was equipped with a denuder to remove organic gases from the incoming air stream evidencing a relevant role of organic sampling artefacts in light absorption measurements by filter-based systems. [Copyright &y& Elsevier]

During collection on filter-based aerosol samplers, organic and inorganic aerosol compounds both contribute to positive and negative artefacts, significantly affecting chemical analyses results for single species and PM mass concentrations. Up to now, studies on organic or inorganic artefacts have been conducted in Europe but very scarce data are available for both in a single study. The field study was carried out in Milan, which is located in the Po valley (Northern Italy) one of the major pollution hot spots in Europe. As sampling artefacts depend on many factors, such as filter type, face velocity, sampling duration, and ambient conditions, in this field study two different filter types have been considered (i.e. quartz fibre filters and Teflon filters) for the assessment of both inorganic and organic artefacts during two different seasons (performing also some samplings at different flow-rates). Results showed that positive artefacts due to OC adsorption on quartz filters accounted for 39% of the OC measured concentration in summer, and 23% in winter. Negative artefact due to nitrate volatilisation by the filters was 51% on Teflon and 22% on the quartz filters in summer, and no or negligible losses were observed in winter. A significant improvement in the PM mass comparability obtained in parallel samplings on different filters was obtained taking into account the artefact estimates performed in this study. [Copyright &y& Elsevier]

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 1μm) 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. [Copyright &y& Elsevier]

In this paper, results on a PM10 daytime–nighttime measurement campaign carried out in Milan to study the evolution of PM10 concentration and composition in relation to atmospheric dispersion conditions are shown. To account for the evolution of atmospheric dispersion conditions, Radon hourly concentration measurements were performed. The significant correlation between PM10 and 222Rn daytime concentrations evidences the dominant role of atmospheric dispersion in determining the temporal variation of PM10 levels. Whenever 222Rn concentrations accumulate during the night (indicating the formation of nocturnal atmospheric stability conditions), PM10 concentrations are higher than those registered during the daytime before, despite a decrease in emissions from active sources. On the contrary, when 222Rn concentrations do not accumulate during night hours, PM10 levels are lower than those measured during the daytime before. As concerns the average elemental concentrations (in ngm−3), the nighttime–daytime variations are in the range −17% to +37%; during the night, soil-related elements (Al, Si, Ca, Ti) decrease while anthropogenic elements (Zn, Cu, Fe, Pb) increase. A case study concerning a ‘green’ Sunday (when traffic was forbidden from 8a. M. To 8p. M. ) is also discussed. The difference of PM10 concentration and elemental composition registered during the ‘green’ Sunday daytime and the following nighttime, together with the information on atmospheric dilution power obtained by Radon measurements, allowed the characterisation of the traffic source elemental profile and increased the comprehension of the low effectiveness of some PM10 reduction strategies. [Copyright &y& Elsevier]

Abstract: Weekly measurements of 210Pb activity concentration on aerosol particles were performed at ground level in outdoor air in Milan (Italy) during the years 2000–2001. The experimental method was based on the delayed alpha spectrometry of in-grown 210Po activity detected on airborne particles collected on a filter support. On the same filter the 214Pb activity concentration was also measured during the sampling. 210Pb weekly concentration values showed a great variability and the average monthly values exhibited a seasonal pattern characterised by maxima in winter and minima in spring–summer. The same seasonal trend was also observed in 214Pb concentration values. 210Pb average yearly values were 0.70 and 0.82mBq/m3 in 2000 and 2001, respectively, in good agreement with literature data registered at continental sites of similar latitude and longitude. The activity ratio 210Pb/214Pb was used to evaluate the residence time of fine aerosols in the urban air of Milan, which was 1–2 days. [Copyright &y& Elsevier]

The seasonal variation of PM1 and PM2.5 mass concentration and composition has been investigated in the great urban area of Milan. PM samplings were carried out 3 times a week during the year 2002. Mass and elemental concentrations were measured in all samples and in a limited number of filters also the elemental and organic carbon contribution (EC and OC) was determined.In the urban area of Milan, PM2.5 comprises about 60% and 70% of the PM1 mass in summer and in winter, respectively. Among the measured PM components carbon compounds and sulphates are by far the major contributors and a significant contribution likely due to nitrates (not measured) should also be considered. PM1 and PM2.5 concentration and composition show a strong seasonal behaviour, which was studied in relation to atmospheric dispersion conditions.Our approach is based on the use of Radon concentration as a natural tracer of differences in the average mixing layer height during the year. The application of a suitable “Radon index” allows the normalisation of PM mass and elemental data to account for the seasonal effect due to differences in atmospheric dispersion conditions. [Copyright &y& Elsevier]

A new methodology based on optical parameters from integrating nephelometer measurements and chemically speciated PM10 mass concentrations, to associate intensive optical parameters with pollution sources identified by the Positive Matrix Factorization (PMF) technique, is presented. PM10 samplings and integrating nephelometer measurements at 450, 525, and 635 nm, co-located in space and time, were performed from November 2011 to November 2012. The PM10 samples were chemically characterized for 16 species, including ions (Na+, NH 4 +, K+, Mg2+, Ca2+, Cl−, NO 3 −, and SO 4 2−), metals (Al, Cd, Cu, Fe, Mn, and Ti), OC, and EC. The scattering σ s and backscattering β s coefficients at 450, 525, and 635 nm, and the PM10 chemically speciated data were used as input of the PMF model. Traffic (TRA, 28.3%), Biomass Burning and Nitrates (BBN, 27.4%), Soil Dust (SDU, 14.7%), ammonium Sulphate (SUL, 17.0%), and Aged Sea-salt (ASS, 12.6%) were the identified pollution sources, according to the PM10 mass apportionment, which did not show any significant difference in terms of source assignment and contribution, with respect to the solution without optical variables. The possibility of retrieving intensive optical parameters associated with the pollution sources from the related spectrally resolved σ s and β s values is the main feature of the proposed approach. The mass scattering efficiency (Σ PM10), the scattering Ångstrom exponent (Å), the spectral curvature of the scattering Ångstrom exponent (ΔÅ), and the asymmetry parameter (g) were the main intensive parameters calculated at different wavelengths or wavelength pairs to characterize the identified pollution sources. Σ PM10 and g at 450 nm, Å (450, 635 nm) and ΔÅ were equal to 3.4 m2 g−1, 0.57, 0.96, and 0.54 for the TRA-source, to 5.0 m2 g−1, 0.58, 1.57, and − 0.06 for the BBN-source, to 5.0 m2 g−1, 0.67, 1.54, and 0.24 for the SUL-source, and to 0.6 m2 g−1, 0.33, −0.65, and 0.12 for the ASS-source, respectively. The analysis of monitoring days with a prevailing pollution source and the comparison of the paper's results with literature values have demonstrated the reliability of the used methodology. • A new methodology based on the PMF source apportionment was developed. • PMF was applied to nephelometer data and chemically speciated PM10 concentrations. • PMF identified traffic, biomass burning, soil dust, sulphate, and sea salt sources. • Sources were characterized by chemical profiles and intensive optical parameters. • Mass scattering efficiency differences among identified sources were highlighted. [ABSTRACT FROM AUTHOR]

Results obtained during a winter field campaign for the fine fractions of particulate matter are presented. A high pollution episode together with an analysis of the main factors, which influence accumulation of pollutants is described. The measurement campaigns were carried out simultaneously at two sites in Northern Italy, Milan and Erba, during the winter of 2000. The daily variability in the mass concentration values and PM2.5/PM10 ratios appeared to be strongly dependent upon meteorological and atmospheric stability conditions and, in particular, wind regimes. During the intensive field campaign a high-pollution episode occurred that led to TSP and fine fraction concentrations well above the attention and alarm thresholds, reaching values of up to 200–250 μg m−3. The elemental concentrations were determined by ED-XRF analysis. The elemental composition of the particulate matter indicated that crustal matter oxides (soil dust) were the main component in particles with aerodynamic diameter dae>10 μm. They were an important part also in particles with 2.5

Estimates of light extinction and visibility are routinely performed by the U.S. Interagency Monitoring of Protected Visual Environments (IMPROVE) network using a simple algorithm which assesses light extinction coefficient (b ext ) at remote and rural sites from concentrations of major particulate matter (PM) species, NO 2 , and Rayleigh scattering from clear-air gaseous components. Following the same approach, in this paper an equation with tailored (i.e. site-specific) coefficients was implemented with the aim of reducing uncertainties and assumptions of the IMPROVE algorithm for applications at polluted urban sites. Major differences compared to IMPROVE algorithm are: 1) dry mass extinction efficiencies calculated using a discrete dipole approximation code with aerosol size distributions measured at our monitoring site as input data; 2) site-specific water growth functions computed separately for ammonium sulfate, ammonium nitrate, and organic matter; 3) fine soil evaluated using an equation previously adopted at our urban site; 4) aerosol absorption component assessed directly through filter-based optical measurements. Details about the calculations performed are reported in the paper and the comparison with the IMPROVE revised algorithm is discussed. The tailored approach here proposed to estimate reconstructed light extinction was applied to PM 2.5 test samples collected on purpose in Milan (Italy), where heavy pollution episodes occur during winter periods. In addition, visual range was calculated applying the Koschmieder equation and compared to visibility measured at the nearby Milano-Linate airport obtaining a fairly good correlation. [ABSTRACT FROM AUTHOR]

A comprehensive range of gas and particle phase pollutants were sampled at 1-hour time resolution in urban background Milan during summer 2012. Measurements include several soluble inorganic aerosols ( Cl − , NO 2 − , NO 3 − , SO 4 2 − , Ca 2 + , K + , Mg 2 + , Na + , NH 4 + ) and gases (HCl, HNO 2 ,HNO 3 , NH 3 , NO, NO 2 ,O 3 , SO 2 ), organic, elemental and black carbon and meteorological parameters. Analysis methods used include mean diurnal pattern on weekdays and Sundays, pollution roses, bivariate polar plots and statistical models using backtrajectories. Results show how nitrous acid (HONO) was mainly formed heterogeneously at nighttime, with a dependence of its formation rate on NO 2 consistent with observations during the last HONO campaign in Milan in summer 1998, although since 1998 a drop in HONO levels occurred following to the decrease of its precursors. Nitrate showed two main formation mechanisms: one occurring through N 2 O 5 at nighttime and leading to nitrate formation onto existing particles; another occurring both daytime and nighttime following the homogeneous reaction of ammonia gas with nitric acid gas. Air masses reaching Milan influenced nitrate formation depending on their content in ammonia and the timing of arrival. Notwithstanding the low level of SO 2 in Milan, its peaks were associated to point source emissions in the Po valley or shipping and power plant emissions SW of Milan, beyond the Apennines. A distinctive pattern for HCl was observed, featured by an afternoon peak and a morning minimum, and best correlated to atmospheric temperature, although it was not possible to identify any specific source. The ratio of primary-dominated organic carbon and elemental carbon on hourly PM 2.5 resulted 1.7. Black carbon was highly correlated to elemental carbon and the average mass absorption coefficient resulted MAC = 13.8 ± 0.2 m 2 g −1 . It is noteworthy how air quality for a large metropolitan area, in a confined valley and under enduring atmospheric stability, is nonetheless influenced by sources within and outside the valley. [ABSTRACT FROM AUTHOR]

In Po valley (Northern Italy) concentrations of particulate matter (PM) often exceed air quality standards, and road traffic is reported as one of the main sources of pollution. This study investigates the size resolved particle number concentration and size distribution at one rural station, one urban station and one traffic station. The measured size-resolved particle number concentration has been reduced by means of cluster analysis to four particle size fractions (cluster 1: 7–29 nm, cluster 2: 29–95 nm, cluster 3: 95–264 nm, and cluster 4: 264–10,000 nm) based on their behavior in atmosphere according to common time patterns. The primary emissions from traffic are evaluated based on black carbon (BC) and size-resolved particle number concentration data, considering separately single size intervals and providing cluster-resolved information on primary and newly formed particle concentration. Particles directly emitted by vehicle exhaust exhibit similar numbers for the clusters 1 to 3 while newly formed particles mainly occurs in cluster 1. Furthermore, diurnal variation of directly emitted particles is found to closely follow the BC levels, while the trend of newly formed particles varies according to air temperature, solar radiation and particle pollution levels. The results release that in Po valley the variations of particle number levels do not always reflect the variation of road traffic emissions in urban areas as the large availability of anthropogenic precursors can favor summertime nucleation events with region-wide extension. [ABSTRACT FROM AUTHOR]

Advanced receptor models have been recently developed and tested in order to improve the resolution of apportionment problems reducing rotational ambiguity of results and aiming at identifying a larger number of sources. In particular, multi-time model is a factor analysis method able to compute source profiles and contributions using aerosol compositional data with different time resolutions. Unlike traditional factor analysis, each measured value can be inserted into multi-time model with its original time schedule, thus all temporal information can be effectively used in the modelling process. In this work, multi-time model was expanded in order to impose constraints on modelled factors aiming at improving the source identification. Moreover, as far as we know for the first time, a suitable bootstrap technique was implemented in the multi-time scheme to estimate the uncertainty of the final constrained solutions. These implemented approaches were tested on a PM2.5 (particulate matter with aerodynamic diameter < 2.5 μm) dataset composed of 24-h samples collected during one year and hourly data sampled in parallel for two shorter periods in Florence (Italy). The daily samples were chemically characterised for elements, ions and carbonaceous components while elemental concentrations only were available for high-time resolved samples. The application of the advanced model revealed the major contribution from traffic (accounting for 37% of PM2.5 as annual average) and allowed an accurate characterisation of involved emission processes. In particular, exhaust and non-exhaust emissions were identified. The constraints imposed in the continuation run led to a better description of the factor associated to nitrates and also of biomass burning profile and the bootstrap results gave useful information to assess the reliability of source apportionment solutions. Finally, the comparison with the results computed by ME-2 base model applied to daily and hourly compositional data separately demonstrated the advantages provided by the multi-time approach. [ABSTRACT FROM AUTHOR]

Most air quality studies on particulate matter (PM) are based on 24-h averaged data; however, many PM emissions as well as their atmospheric dilution processes change within a few hours. Samplings of PM with 1-h resolution can be performed by the streaker sampler (PIXE International Corporation), which is designed to separate the fine (aerodynamic diameter less than 2.5 μm) and the coarse (aerodynamic diameter between 2.5 and 10 μm) fractions of PM. These samples are efficiently analyzed by Particle Induced X-ray Emission (PIXE) at the LABEC laboratory of INFN in Florence (Italy), equipped with a 3 MV Tandetron accelerator, thanks to an optimized external-beam set-up, a convenient choice of the beam energy and suitable collecting substrates. A detailed description of the adopted set-up and results from a methodological study on the detection limits for the selection of the optimal beam energy are shown; the outcomes of the research on alternative collecting substrates, which produce a lower background during the measurements, and with lower contaminations, are also discussed. [ABSTRACT FROM AUTHOR]

In this paper, a new way to apportion the absorption coefficient (b abs ) of carbonaceous atmospheric aerosols starting from a multi-wavelength optical analysis is shown. This methodology can disentangle and quantify the contribution to total absorption of equivalent black carbon (EBC) emitted by wood burning (EBC WB ) and fossil fuel (EBC FF ) as well as brown carbon (BrC) due to incomplete combustion. The method uses the information gathered at five different wavelengths in a renewed and upgraded version of the approach usually referred to as Aethalometer model. Moreover, we present the results of an apportionment study of carbonaceous aerosol sources performed in a rural area and in a coastal city, both located in the North-West of Italy. Results obtained by the proposed approach are validated against independent measurements of levoglucosan and radiocarbon. At the rural site the EBC WB and EBC FF relative contributions are about 40% and 60% in winter and 15% and 85% in summer, respectively. At the coastal urban site, EBC WB and EBC FF are about 15% and 85% during fall. The OC contribution to the wood burning source at the rural site results approximately 50% in winter and 10% in summer and about 15% at the coastal urban site in fall. The new methodology also provides a direct measurement of the absorption Ångström exponent of BrC (α BrC ) which resulted α BrC = 3.95 ± 0.20. [ABSTRACT FROM AUTHOR]

A comparison exercise on thermal-optical elemental carbon/organic carbon (ECOC) analysers was carried out among 17 European laboratories. Contrary to previous comparison exercises, the 17 participants made use of an identical instrument set-up, after correcting for temperature offsets with the application of a recently developed temperature calibration kit (Sunset Laboratory Inc, OR, US). Temperature offsets reported by participants ranged from –93 to +100 °C per temperature step. Five filter samples and two sucrose solutions were analysed with both the EUSAAR2 and NIOSH870 thermal protocols. z scores were calculated for total carbon (TC); nine outliers and three stragglers were identified. Three outliers and eight stragglers were found for EC. Overall, the participants provided results between the warning levels with the exception of two laboratories that showed poor performance, the causes of which were identified and corrected through the course of the comparison exercise. The TC repeatability and reproducibility (expressed as relative standard deviations) were 11 and 15% for EUSAAR2 and 9.2 and 12% for NIOSH870; the standard deviations for EC were 15 and 20% for EUSAAR2 and 20 and 26% for NIOSH870. TC was in good agreement between the two protocols, TCNIOSH870 =0.98×TCEUSAAR2 (R2 = 1.00, robust means). Transmittance (TOT) calculated EC for NIOSH870 was found to be 20% lower than for EUSAAR2, ECNIOSH870 D0.80×ECEUSAAR2 (R2 = 0.96, robust means). The thermograms and laser signal values were compared and similar peak patterns were observed per sample and protocol for most participants. Notable deviations from the typical patterns indicated either the absence or inaccurate application of the temperature calibration procedure and/or pre-oxidation during the inert phase of the analysis. Low or zero pyrolytic organic carbon (POC), as reported by a few participants, is suggested as an indicator of an instrument-specific pre-oxidation. A sample-specific preoxidation effect was observed for filter G, for all participants and both thermal protocols, indicating the presence of oxygen donors on the suspended particulate matter. POC (TOT) levels were lower for NIOSH870 than for EUSAAR2, which is related to the heating profile differences of the two thermal protocols. [ABSTRACT FROM AUTHOR]

In this study, the Multilinear Engine (ME-2) receptor model was applied to speciated particulate matter concentration data collected with two different measuring instruments upwind and downwind of a steelworks complex in Port Talbot, South Wales, United Kingdom. Hourly and daily PM samples were collected with Streaker and Partisol samplers, respectively, during a one month sampling campaign between April 18 and May 16, 2012. Daily samples (PM 10 , PM 2.5 , PM 2.5–10 ) were analysed for trace metals and water-soluble ions using standard procedures. Hourly samples (PM 2.5 and PM 2.5–10 ) were assayed for 22 elements by Particle Induced X-ray Emission (PIXE). PM 10 data analysis using ME-2 resolved 6 factors from both datasets identifying different steel processing units including emissions from the blast furnaces (BF), the basic oxygen furnace steelmaking plant (BOS), the coke-making plant, and the sinter plant. Steelworks emissions were the main contributors to PM 10 accounting for 45% of the mass when including also secondary aerosol. The blast furnaces were the largest emitter of primary PM 10 in the study area, explaining about one-fifth of the mass. Other source contributions to PM 10 were from marine aerosol (28%), traffic (16%), and background aerosol (11%). ME-2 analysis was also performed on daily PM 2.5 and PM 2.5–10 data resolving 7 and 6 factors, respectively. The largest contributions to PM 2.5–10 were from marine aerosol (30%) and blast furnace emissions (28%). Secondary components explained one-half of PM 2.5 mass. The influence of steelworks sources on ambient particulate matter at Port Talbot was distinguishable for several separate processing sections within the steelworks in all PM fractions. [ABSTRACT FROM AUTHOR]

Abstract: Water soluble ions, methanesulfonate, organic and elemental carbon, and metals in PM2.5 and PM1 samples were analysed by Positive Matrix Factorization to identify and quantify major sources of fine particles at a Central Mediterranean site. The cluster analysis of four-day back trajectories was used to determine the dependence of PM2.5 and PM1 levels and composition on air-flows. The cluster analysis has identified six, six, and seven distinct air-flow types arriving at 500, 1500, and 3000 m above sea level (asl), respectively. Slow-west (Wslow) and north-eastern (NE) flows at 500 and 1500 m asl were the most frequent and were associated with the highest PM2.5 and PM1 concentrations. The PM concentrations from combustion sources including biomass burning were at their maximum under north-western (NW) flows. Similarly, the ammonium sulphate source was enhanced under Wslow and NE flows. South-eastern Mediterranean Sea air-flows were associated with the highest PM2.5 concentrations due to the heavy-oil-combustion source and the highest PM2.5 and PM1 concentrations due to the secondary marine source. PM2.5 concentrations due to the reacted dust and traffic source and PM1 concentrations due to the nitrate with reacted dust and mixed anthropogenic source showed no clear dependence on air-flows. This work highlights the different impact of aerosol sources on PM2.5 and PM1 fractions, being PM1 more adequate to control anthropogenic emissions from combustion sources. [Copyright &y& Elsevier]

Abstract: We introduce a simple, fully automatic, multi-wavelength and non-destructive optical system, namely a Multi-Wavelength Absorbance Analyzer (MWAA), to measure off-line the light absorption in Particulate Matter (PM) collected on filters and hence to derive the black and brown carbon content in the PM. This gives the opportunity to measure in the same sample the concentration of PM mass by gravimetric analysis, black and brown carbon, elements by, for instance, X Ray Fluorescence, and finally ions by Ion Chromatography. Furthermore, the multi-wavelength analysis gives the possibility to apportion black and brown/organic carbon sources through the direct determination of the Angstrom exponent and a revised version of the so-called “the aethalometer method”. Up to 16 samples can be analyzed in sequence and in an automatic and controlled way within a few hours. The filter absorbance measured by MWAA was successfully validated both against a MAAP and a polar photometer. Our MWAA was used in several field campaigns with PM2.5 (PM with aerodynamic diameter less than 2.5μm) samples collected on quartz fiber filters, and the mass absorption cross section at λ=405, 635 and 850nm was obtained measuring at the same time the EC in particulate matter samples by thermal-optical analysis using the EUSAAR_2 protocol. First results on the MWAA application to the analysis of size-segregated samples collected by multi-stage impactor are also shown. [Copyright &y& Elsevier]

Abstract: This work aims at gaining information on the effects of different thermal treatments on radiocarbon measurements of organic (OC) and elemental (EC) carbon fractions in the atmospheric aerosol. Improvements to the traditional approaches for the determination of the fraction of modern carbon of OC and EC−f m(OC) and f m(EC)- are proposed. As for f m(EC) determination, we propose to add a He step at high temperature to the standard oxygen treatment. Our tests demonstrate that the addition of a high temperature He step (final choice: 750°C) to the oxygen treatment is effective in removing the refractory OC. As for f m(OC) determination, we propose to quantify it by measuring either the fraction of modern carbon of TC and EC or the fraction of modern carbon of water soluble (f m(WSOC)) and water insoluble (f m(WINSOC)) organic carbon to limit the influence of possible pyrolysis on the direct determination of f m(OC). Tests on the equivalence of the approaches have shown good agreement between them. Our tests were carried out on samples collected in a heavily polluted area (Milan, Italy) during wintertime. f m(OC), f m(EC), and f m(TC) values obtained in our tests were also used to attempt a preliminary source apportionment in the area using 14C measurements. Wintertime EC resulted to be mainly fossil (84%), whereas OC was dominated by modern contribution (63%). Two approaches were tested for the evaluation of the wood burning contribution to OC and a good agreement was found. Wood burning primary contribution accounted for about 18% of OC in Milan during wintertime. Secondary OC from biomass burning and the contribution from other urban sources were tentatively identified following literature approaches, with the aim of evaluating the biogenic contribution to OC in the area, which was estimated to be about 18%. [Copyright &y& Elsevier]

Abstract: In southern European countries, Saharan dust may episodically produce significant increases of PM10, which may also cause the exceedance of the PM10 daily limit value established by the European Directive (2008/50/EC). The detection with very high sensitivity of all the elements that constitute mineral dust makes PIXE technique a very effective tool to assess the actual impact of these episodes. In this work, a review of long-term series of elemental concentrations obtained by PIXE has been accomplished with the aim of identifying the occurrence of Saharan dust transport episodes over long periods in Tuscany and characterising them in terms of composition and impact on PM concentration, tracing back their contribution to the exceedances of the PM10 limit value. The impact of the different Saharan intrusions on PM10 showed a very high variability. During the most intense episodes (which occurred with a frequency of few times per year) the calculated soil dust concentration reached values as high as 25–30 μg m−3, to be compared with background values of the order of 5 μg m−3. The Saharan dust contribution was decisive to cause the exceedance of the PM10 daily limit value in the 1–2% of the days considered in the present work. [Copyright &y& Elsevier]

Abstract: In this work, a methodology based on the macro-tracer approach was improved to obtain a more reliable estimate of the wood burning impact on PM10 and OC concentrations. Indeed, literature emission factors were weighed by the wood consumption data available for the investigated region and these tailored factors were used in the calculation. Moreover, an alternative approach using the chemical profile of the wood burning source obtained by the Positive Matrix Factorization was introduced. As far as we know, this is the first time that PMF-derived emission ratios instead of source emission factors are used in the macro-tracer method. A critical comparison of the results obtained by the two approaches was carried out. The results suggest that PMF-derived emission ratios can be a feasible alternative to the widely used wood smoke emission factors, which show a high variability. The proposed methodology was applied to a trial dataset of wintertime PM10 samples - characterised for anhydrosugars, organic, and elemental carbon – collected in the frame of a regional project. The results gave a preliminary estimate of the wood smoke contribution to PM10 and OC in different sites in Lombardy (Northern Italy). [Copyright &y& Elsevier]

Abstract: The concentration of carbonates in atmospheric Particulate Matter (PM) is usually quite low. The surroundings of marble quarries are peculiar sites where the impact of carbonates in PM levels can be significant. We present here the results of a PM10 sampling campaign performed in Carrara (Italy). The town lies between the famous marble quarries and the harbour: about 1000 trucks per day transport marble blocks and debris from the quarries to the harbour passing through the town centre. PM10 was collected on daily basis on PTFE filters analyzed by Energy-Dispersive X-Ray Fluorescence (ED-XRF) and Ion-Chromatography (IC). Carbonate concentration was measured by a non-destructive Infrared Spectroscopy analysis (FT-IR). Time series of elemental (Na–Pb by ED-XRF), ionic (SO4 2−, NH4 + by ion-chromatography) and carbonate (by FT-IR) concentration values were merged in a unique data set and a PMF analysis singled out the major PM10 sources in the area. Marble transportation turned out to be the major pollution source in the town accounting to PM10 for about 36%; this corresponded to a CaCO3 average level of about 8 μg m−3 during working days. The FT-IR analysis was a crucial part of the work and an ad-hoc analytical procedure was specifically set up, calibrated, and tested as described in the text. [Copyright &y& Elsevier]

Abstract: Radiocarbon measurements on the carbonaceous aerosol fractions have been demonstrated as an effective tool for aerosol source apportionment. For these measurements, a new sample preparation facility was installed at the INFN-LABEC laboratory of Florence (Italy). The line was designed to allow the preparation of samples from different carbonaceous fractions: the combustion of the aerosol samples can be performed in helium or oxygen flows, according to thermal sequences. The evolved CO2 is cryogenically trapped and reduced to graphite, which is the target material for following Accelerator Mass Spectrometry (AMS) 14C measurements. This preparation line is described in detail in the paper. As a first step, the line was tested by means of AMS measurements performed on standards to check the reproducibility and the accuracy of the system; moreover, preliminary measurements on the total carbon fraction in aerosol samples were made. Results of these measurements are also reported. [Copyright &y& Elsevier]

Abstract: An example of an integrated approach to assess air pollution threats to cultural heritage in a semi-confined environment is presented in this work, where the monitoring campaign carried out at the Michelozzo''s Courtyard (in Palazzo Vecchio, Florence, Italy) is used as a case study. A wide research project was carried out, with the main aim of obtaining the first quantitative data on air quality and microclimate conditions inside the Courtyard, and, if possible, identifying the main causes of degradation and suggesting appropriate conservation strategies. The investigation adopted a holistic approach involving thermographic measurements on the wall paintings, microclimatic analysis, gaseous pollutant monitoring, atmospheric particles characterisation and dry deposition compositional analysis. Attention was focused on the wall painting depicting the city of Hall because of its anomalous and critical conservation conditions, which are visible at a glance, due to the contrast between a wide darker zone around the central subject of the painting and external lighter areas. [Copyright &y& Elsevier]

Abstract: European publications dealing with source apportionment (SA) of atmospheric particulate matter (PM) between 1987 and 2007 were reviewed in the present work, with a focus on methods and results. The main goal of this meta-analysis was to provide a review of the most commonly used SA methods in Europe, their comparability and results, and to evaluate current trends and identify possible gaps of the methods and future research directions. Our analysis showed that studies throughout Europe agree on the identification of four main source types ( and ): a vehicular source (traced by carbon/Fe/Ba/Zn/Cu), a crustal source (Al/Si/Ca/Fe), a sea-salt source (Na/Cl/Mg), and a mixed industrial/fuel-oil combustion () and a secondary aerosol source (the latter two probably representing the same source type). Their contributions to bulk PM levels varied widely at different monitoring sites, and showed clear spatial patterns in the cases of the crustal and sea-salt sources. Other specific sources such as biomass combustion or shipping emissions were rarely identified, even though they may contribute significantly to PM levels in specific locations. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

The wall paintings of the Michelozzo’s Courtyard (XVI century) at the main entrance of Palazzo Vecchio in Florence are in an advanced state of degradation. With the aim of understanding the environmental conditions in the Courtyard a wide research project has been instigated. In this study, the fine and coarse fractions of the PM10 have been collected by a ‘streaker’ sampler with an hourly resolution and then analysed by PIXE at the 3MV tandetron accelerator in Florence; the first results will be presented here. [Copyright &y& Elsevier]

Abstract: The composition of particulate matter near a large steel plant, located inside the town of Genoa (Italy), has been studied since July 2004. Several instruments have been used: a sequential sampler, operated on a daily basis and a two-stage continuous streaker sampler. An optical particle counter (OPC) provided the aerosol size distribution with a 1-min time resolution. PIXE and ED-XRF analysis were performed on the aerosol samples. In particular, the streaker frames were analyzed by PIXE at the new external proton beam facility of INFN-Florence whereas the daily filters were measured by ED-XRF in Genoa. We present here results obtained in a part of the campaign when all the above quoted devices have been operated simultaneously. [Copyright &y& Elsevier]

Abstract: The particulate matter (PM) concentration and composition, the PM10, PM2.5, PM1 fractions, were studied in the urban area of Genoa, a coastal town in the northwest of Italy. Two instruments, the continuous monitor TEOM and the sequential sampler PARTISOL, were operated almost continuously on the same site from July 2001 to September 2004. Samples collected by PARTISOL were weighted to obtain PM concentration and then analysed by PIXE (particle induced X-ray emission) and by ED-XRF (energy dispersion X-ray fluorescence), obtaining concentrations for elements from Na to Pb. Some of the filters used in the TEOM microbalance were analysed by ED-XRF to calculate Pb concentration values averaged over 7–30d periods. [Copyright &y& Elsevier]

The paper presents methodological innovations introduced in the characterisation of urban aerosol collected in Italy in a recent campaign. Two complementary ion beam analysis (IBA) techniques were used to analyse Nuclepore filters used in continuous streaker samplers to collect airborn particles in four Italian towns. Na to Pb elemental concentrations were obtained by particle induced X-ray emission (PIXE), while time of flight secondary ion mass spectrometry (ToF-SIMS) produced, on the same samples, time trends for several elements and molecular fragments. In addition, light attenuation measurements were used as a tracer for black carbon. The data produced by these three techniques was merged into a unique data set to address the characterisation of particulate matter sources. Correlations between elemental concentration trends (PIXE) and relative trends for molecular fragments (ToF-SIMS) and black carbon (light attenuation) have been studied by cluster and principal component analysis. [Copyright &y& Elsevier]

In this paper a source apportionment of particulate matter pollution in the urban area of Milan (Italy) is given. Results of PM10 and PM2.5 mass and elemental concentrations from a 1-year monitoring campaign are presented. Mean annual and daily PM10 levels are compared with the limits of the EU Air Quality Directive EC/30/1999 and the results show that the limit values established would not be met in the urban area of Milan or the large surrounding area. Moreover, high levels of PM2.5 are registered and this fraction constitutes a high portion of the PM10 mass. In Milan the winter period is characterised by a high degree of air pollution due to a greater contribution of emissions and to adverse meteorological and thermodynamic conditions of the atmosphere. The application of multivariate techniques and receptor modelling (PCFA, APCFA) to the whole data-set led to the identification of the main emitting sources and to the source apportionment of PM10 and PM2.5 in Milan. The most important sources were identified as ‘soil dust’, ‘traffic’, ‘industry’ and ‘secondary compounds’ for PM10 and as ‘soil dust’, ‘anthropogenic’ and ‘secondary compounds’ for PM2.5, explaining the greatest part of the total variance (91% and 75%, respectively). [Copyright &y& Elsevier]

The composition of particulate matter in the atmosphere of four major italian towns (Florence, Genoa, Milan and Naples) has been studied with hourly resolution by means of ion beam analysis (IBA) techniques and statistical methods. The aerosol has been collected simultaneously in the four towns during the first weeks of year 2001, by two-stage continuous streaker samplers, which separate and collect the PM10 particulate matter in two fractions. The hourly concentrations in air of about 20 elements have been extracted in the fine and coarse fractions of PM10 by particle induced X-ray (and gamma-ray) emission, PIXE (and PIGE), analysis of about 2700 hourly samples. The coupled use of streaker samplers and IBA techniques made distinguishable time patterns typical of urban environments as well as fast and occasional episodes. Absolute principal component factor analysis (APCFA) and other statistical approaches have been used to obtain a sintetic apportionment of the sources of particulate matter. [Copyright &y& Elsevier]

Continuous measurement of hourly concentrations of 212Pb attached to aerosol particles was carried out during the whole year 2000 in the outdoor air of Milan (Italy).An improved experimental method based on on-line alpha spectroscopy during atmospheric particulate matter sampling allowed the contemporary determination of 212Pb and 214Bi through the deconvolution of the alpha energy spectral distribution analysis.The 212Pb hourly concentrations were about 100 times lower than 214Bi but showed a similar characteristic diurnal time trend. However, the influence of meteorological parameters such as rain and wind was more evident in 212Pb than in 214Bi concentrations.The 212Pb average annual concentration was 0.090±0.060 Bq/m3 with daily mean concentration varying from 0.013 to 0.333 Bq/m3. [Copyright &y& Elsevier]

The composition of particulate matter in the atmosphere of four major Italian towns (Florence, Genoa, Milan and Naples) has been studied with the extensive application of IBA techniques. The aerosol has been collected simultaneously in the four towns during the first weeks of year 2001, by two-stage continuous streaker samplers, which provide the separation of the particulate matter in two fractions. The concentrations in air of about 20 elements, and the total particulate mass, have been extracted in the PM2.5 and PM10 fractions with hourly resolution by PIXE, PIGE and optical analyses of about 2700 samples. IBA analyses have been performed at the 3 MeV external proton beam of the INFN accelerator facility at the University of Florence. [Copyright &y& Elsevier]

In this paper, measurements of short- and long-lived Radon progeny attached to atmospheric fine aerosols are reported. Hourly measurements of 222Rn short-lived decay products (i.e. 214Bi via on-line alpha spectrometry on 214Po) in the atmosphere were carried out in Milan (Italy) from 1999 to 2016; 214Bi mean concentrations ranged from 0.2 to 38.1 Bq m−3. It is noteworthy that minima occurred in springtime although the strongest convective turbulence can be expected in summer, when the highest solar radiation is available; one order of magnitude higher values were observed in winter when the Po valley experienced poor atmospheric dilution. The Theil-Sen method was applied to investigate the long-time trend in de-seasonalised data series. Results showed that - although inter/intra-annual variations in 214Bi concentrations were observed in connection with differences in atmospheric dispersion conditions – no statistically significant trend over the investigated period was detected. On a sub-set of these samples, also weekly 210Pb concentrations were determined via off-line alpha spectrometry on 210Po; atmospheric activity concentration values ranged between 0.13 and 3.05 mBq m−3. The seasonal behaviour of 210Pb concentrations followed fairly well the 214Bi temporal pattern, showing that mixing layer dynamics is paramount in determining short- and long-lived Radon progeny levels in the atmosphere. From 210Pb/214Bi activity ratio, the residence time τ res of fine aerosols in the atmosphere was estimated to be on average 1 day, ranging from 11.0 to 55.3 h without any evident temporal trend. By exploiting the availability of mixing layer height data at our site, an alternative approach to estimate aerosol residence time was tested; this was based on a simple relationship relying on deposition velocity (from literature data) and mixing layer height (available at our monitoring station). Mean experimental τ res resulted in 1.2 days which was comprised in the 0.6–2.0 days range estimated by the alternative method. This result brings a noteworthy contribution to the scientific debate about differences among aerosol residence time estimates obtained by different radioactive parent-daughter couple; our results show that the 210Pb/214Bi (or equivalently 210Pb/222Rn) couple provides reliable estimates. Unlabelled Image • Natural radioactive isotopes are effective tracers to study atmospheric processes. • Fine aerosol residence times retrieved through long- and short-lived Radon progeny. • Fine aerosol residence times in Milan ranged between 11 and 55 h. • Residence time reliability assessed by deposition velocity and mixing layer height. [ABSTRACT FROM AUTHOR]

c-erbB-2, a member of the tyrosine kinase oncogene family, is overexpressed in about 30% of human breast tumors where it correlates with poor prognosis. In vitro studies have suggested that increased expression of the receptor plays an important role in malignant progression. To better understand the direct effects of p185HER2 overexpression, a human c-erbB-2 expression vector was transfected into the hormone-dependent MCF-7 human breast carcinoma cell line and cell growth was analysed. Unexpectedly, colony formation assay revealed a reduction in the number and size of colonies as compared with mock-transfected cells. In hormone-deprived medium, c-erbB-2 transfected cells acquired growth capability, consistent with previous reports. By contrast, two c-erbB-2-transfected clones grown in complete medium showed a reduced proliferation rate despite the activation of a fully functional oncoprotein capable of autophosphorylation and induction of the MAPK pathway. The number of c-erbB-2-overexpressing cells in the S phase of the cell cycle was about one-half the number of control and mock-transfected cells. Also, overexpression of c-erbB-2 induced overexpression of p21WAF1, pRB hypophosphorylation and a mature differentiated cell phenotype with production of lipid droplets. Functional inactivation of p185HER2 by means of a specific single chain antibody indicated the c-erbB-2-dependence of the observed alterations. These data show that the exogenous overexpression of the c-erbB-2 gene in hormone-dependent breast cancer cells inhibits proliferation and induces differentiation. [ABSTRACT FROM AUTHOR]

In this source apportionment study, an original approach based on receptor modelling was tested to relate primary and secondary organic aerosol (OA) contributions - estimated from ACSM (Aerosol Chemical Speciation Monitor) measurements - to their emission sources. Moreover, thanks to the coupling of optical and chemical variables as input to the receptor model, information such as the impact of mineral dust to the aerosol absorption in the atmosphere and estimates for the absorption Ångström exponent (α) of the sources were retrieved. An advanced source apportionment study using the Multilinear Engine (ME-2) was performed on data collected during February 2017 in Rome (Italy), in the frame of the CARE (Carbonaceous Aerosol in Rome and Environs) experiment. A complete chemical characterisation (elements, non-refractory components, and carbonaceous components) was carried out, and the aerosol absorption coefficients b ap (λ) at 7 wavelengths (370, 470, 520, 590, 660, 880, and 950 nm) were retrieved by an Aethalometer AE33; all these variables (chemical + optical) were used as input to the receptor model. The final constrained solution consisted of nine factors which were assigned to major sources impacting on the investigated site (hereafter sources are referred to as: biomass burning, nitrate and aged aerosol, traffic exhaust, sulphate, mineral dust, marine aerosol, traffic non-exhaust, local source, and polluted marine aerosol), comprising both local urban sources and contributions from long-range transport. The bootstrap analysis supported the goodness of the solution. Total OA concentration from ACSM was apportioned by our receptor model and afterwards compared with HOA (hydrocarbon-like organic aerosol), BBOA (biomass burning-like organic aerosol), and OOA (oxygenated organic aerosol) concentrations obtained as results from an independent source apportionment study previously performed. As an original result of this work, insights on OA contributions were thus retrieved: (1) the contribution of organic aerosol assigned by ME-2 to the traffic exhaust source was fully comparable to HOA assessed by ACSM data analysis; (2) our source apportionment results gave the relevant indication that the OOA apportionment made on ACSM data likely includes a secondary OA contribution due to biomass burning. Other relevant results came from b ap apportionment obtained by our multi-variable source apportionment approach: traffic exhaust was the main contributor to aerosol absorption in the atmosphere, but mineral dust contribution was also notable when a not negligible mineral dust transport episode was registered at the measurement site. In addition, source dependent optical absorption parameters (i.e. the absorption Ångström exponent - α - and the mass absorption cross section at different wavelengths) were retrieved without any a-priori assumption. In perspective, our modelling approach paves the way to more powerful source apportionment approaches which have the potential of providing much more insights on aerosol properties and sources. Image 1 [ABSTRACT FROM AUTHOR]

The "Carbonaceous Aerosol in Rome and Environs" (CARE) experiment took place at a Mediterranean urban background site in Rome (Italy) deploying a variety of instrumentation to assess aerosol physical-chemical and optical properties with high-time resolution (from 1 min to 2 h). In this study, aerosol optical properties, chemical composition, and size distribution data were examined with a focus on the analysis of several intensive optical properties obtained from multi-wavelength measurements of aerosol scattering and absorption coefficients. The spectral behaviour of several quantities related to both aerosol composition and size was explored, analysing their high-time resolved temporal patterns and combining them in order to extract the maximum information from all the available data. A methodology to separate aerosol types using optical data only is here proposed and applied to an urban area characterised by a complex mixture of particles. A key is given to correctly disentangle cases that could not be distinguished observing only one or few parameters, but that can be clearly separated using a suitable ensemble of optical properties. The SSCAAE, i.e. the wavelength dependence of the Single Scattering co-albedo 1-SSA (where SSA is the Single Scattering Albedo) - that efficiently responds to both aerosol size and chemical composition – resulted to be the best optical intensive parameter to look at for the discrimination between episodes characterised by specific aerosol types (e.g. sea salt, Saharan dust) and more mixed conditions dominated by local emissions. However, this study also highlighted that it is necessary to combine temporal patterns of different optical parameters to robustly associate SSCAAE features to specific aerosol types. In addition, the complete chemical speciation and the high-time resolved size distribution were used to confirm the aerosol types identified via a combination of aerosol optical properties. Look-up tables with most suitable ranges of values for optical variables were produced; therefore, these pieces of information can be used at the same site or at locations with similar features to quickly identify the occurrence of aerosol episodes. Graphical frameworks (both from the literature and newly designed) are also proposed; for each scheme features, advantages, and limitations are discussed. • Combination of intensive optical parameters discriminates aerosol types. • High-time resolved composition and size distribution support the identification. • The methodology produces look-up tables useful for real-time implementation. • High PM events origin can be identified by optical parameters only. [ABSTRACT FROM AUTHOR]