G. Marcazzan

Characterisation of PM10 and PM2.5 particulate matter in the ambient air of Milan (Italy)

Abstract 24-h simultaneous samplings of PM10 and PM2.5 particulate matter (PM) have been carried out during the period December 1997–September 1998 in the central urban area of Milan. The mass concentrations of the two fractions showed significant daily variations linked to different thermodynamic conditions of the planetary boundary layer (PBL) and characterised by higher values during wintertime. The elemental composition, determined by energy dispersive X-ray fluorescence technique, was quite different in the two fractions: in the finer one the presence of elements with crustal origin is reduced while the anthropogenic elements, with a relevant environmental and health impact, appear to be enriched. The composition data allowed a quantification of two major components of the atmospheric particulate: sulphates (mainly of secondary origin) and particles with crustal origin. An important but unmeasured component is likely constituted by organic and elemental carbon compounds. The multivariate analysis of elements, gaseous pollutants and mass concentration data-sets leads to the identification of four main sources contributing to PM10 and PM2.5 composition: vehicles exhaust emissions, resuspended crustal dust, secondary sulphates and industrial emissions. The existence of a possible background component with non-local origin is also suggested.

Long period study of outdoor radon concentration in Milan and correlation between its temporal variations and dispersion properties of atmosphere

The results of a survey of outdoor radon concentrations in Milan are reported. Measurements were performed hourly over a continuous four year period from January 1997 to December 2000. Radon concentration was obtained by two means: both direct measurement of radon; and measurement of its decay products. The average daily pattern of radon concentration featured a minimum in the late afternoon and a maximum in the early hours of the morning. A seasonal pattern with higher concentrations in winter than in summer (from around 15 Bq m(-3) in winter to around 5 Bq m(-3) in summer) was also observed. Similar average annual values of around 10 Bq m(-3) were obtained. The annual effective outdoor radon dose was found to be 0.12 mSv. The variation from minimum in the afternoon to maximum the following morning was found to be a good indicator of the height of the nocturnal mixing layer. The variation between maximum and minimum levels on the same day is an index of the maximum height of the mixing layer. Furthermore, our long term measurements of radon have permitted us to examine the dispersion characteristics of the atmosphere over Milan, and to establish the frequency of conditions unfavourable to the dispersion of atmospheric pollutants.

Hourly elemental composition and sources identification of fine and coarse PM10 particulate matter in four Italian towns

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.

Factors influencing mass concentration and chemical composition of fine aerosols during a PM high pollution episode

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 microg 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 d(ae) > 10 microm. They were an important part also in particles with 2.5 < d(ae) < 10 microm, but strongly decreased in particles with d(ae) < 2.5 microm. In the finer fraction sulphates nitrogen and carbon compounds played a major role. The temporal patterns of mass and elemental concentrations, as well as the main components of PM were very similar at the two sites. The high-pollution episode was recorded at many locations in the Po plain, highlighting the role of meteorology and thermodynamic atmospheric conditions on pollution build-up on a large area.

Temporal variation of 212Pb concentration in outdoor air of Milan and a comparison with 214Bi

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.

Aerosol characterisation in Italian towns by IBA techniques

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.

Bulk and Surface Studies of Fly Ash Particles

Coal and oil combustion produces fly ash particulates whose dispersion into the environment represents one of the major sources of pollution.

PIXE‐PIGE Analysis Of Aerosol Composition In Urban Italian Environments

Fine particulate has become one of the biggest concerns in Italian cities pollution; the study of its composition is a powerful tool to evaluate the effects on health and identify pollution sources. PIXE is an established technique for particulate analysis (being multi‐elemental, sensitive, fast, non‐destructive and requiring no sample preparations) and has been extensively used, in combination with other IBA techniques, for particulate characterization in Italian urban environments. Here we report the preliminary results on the analysis of the aerosol collected, by two‐stage continuous streaker samplers, in two Italian cities, Florence and Milan, during July 2001. Elemental concentrations have been extracted in the fine and coarse fractions, with hourly resolution, by PIXE‐PIGE analysis, performed at the 3 MeV external proton beam INFN facility at the University of Florence.