MINERALOGICAL METHODS FOR THE CHARACTERIZATION OF 2.5 PARTICULATE MATTER IN THE URBAN AREA OF ROME, ITALY.

The characterization of the airborne particulate represents a real issue. Many studies have examined the effects of the particulate matter on human health suggesting that the small particles represent a severe problem. In the present work chemical and mineralogical investigations on the particulate matter of the city of Rome were carried out. The particulate samples (PM2.5) were collected in Rome since April 2010. Polycarbonate filters were used to trap and recover airborne particles according to a standard procedure, and then utilized for different analytical techniques. Preliminary investigations on PM2.5 filters (SEM-EDS, X-ray and DTA) provided information about the inorganic compound. High iron content was highlighted as oxides, hydro-oxides, and sulphates. In particular, the presence of melanterite FeSO4.7(H2O)[1] was evidenced. Ca-sulphates and clays were also found. Moreover, innovative methodologies, such as Atomic Force Microscopy (AFM), resulted useful for morphological and dimensional investigations of the micro and nano-particles[2]. Hygroscopic properties of mixed urban aerosol can be monitored by FT-IR. Furthermore a complete functional group characterization of PM2.5 phases in the 4000-400 cm-1 spectral range, with a procedure based on diffuse reflectance (DRIFT), is in progress. The association in the atmospheric dust particles of amorphous phases and heavy metals is known to increase the release of these dangerous chemical elements. To obtain the bulk chemical composition of the particulate material the Regional Protection Agency usually utilize ion mass spectrometry (ICP-MS) on a little amount of particulate matter (2 mg; D.M. 60/2002). In this work ICP-MS analyses were performed on a high content of material (35 mg). The high amount was here used to investigate the presence of heavy metals and their release in biological environment. Data on PM2.5 samples was fully comparable with those typically observed by Regional Protection Agencies (ARPA). Test of release were executed in physiological solution (PH 7.4, 37 °C, 30 days). Release evidence were obtained for Fe, V, Pb, As and Cr. These results confirm that the release of heavy metals in the biological environments already occurs from the first hours. In vitro experiments are in progress to assess the relation between the fine and ultrafine particles and the health effects.