, a period characterised by two episodes of Saharan dust outbreaks in Italy, particulate matter (PM) samples were collected at two stations (urban and suburban) in Rome. Some samples were selected and analysed using the SEM-EDS technique to characterise PM, focussing especially on the mineral contribution. Samples were representative both of days affected by Saharan dust episodes and days without this contribution. Cluster analysis allowed the attribution of each of about 67 000 analysed particles to one of the seven main statistical groups based on their composition. Characteristics of the particulate components identified using SEM-EDS analysis were verified by PIXE analysis carried out on filters collected in a suburban area. Ultimately, the contribution of crustal particles was revealed to be consistently high, highlighting the importance of local and regional mineral contributions, as well as those of Saharan origin. Therefore, quantifying all mineral contributions to resuspended particulate could lead to significant reductions of the PM level also on days not influenced by Saharan dust, thus limiting conditions when PM 10 daily limit value (DLV) established by European legislation is exceeded.

The relevance of dust outbreaks from the Sahara into Italy was evaluated for the period from 2001 to 2007. To this end, days affected by Saharan dust were recognized at four PM(10) background stations belonging to the Regional Agencies for Environmental Protection (ARPA) monitoring networks (one working in the 2005-2007 period only). The analysis included computation of back trajectories, complemented with satellite images and meteorological charts. Results from other models are also collected for comparison. Saharan Dust contribution to PM(10) was calculated referring to a method developed for Iberian monitoring networks. PM(10) exceeding the daily limit value (DLV) of the European Union air quality standard were reviewed also. The provenience of air masses yielding the exceedances was also recognized, allowing to distinguish the Atlantic-European episodes from the (Atlantic)-Saharan ones. The European episodes are due to anthropogenic pollution that affected mainly northern Italy in winter; instead, the Saharan ones are due to dust outbreaks that affected mainly southern Italy in summer. Central Italy is characterised by a transitional situation that is experienced from north to south. A number of dust affected days with DLV exceedance (from 4 to 108 at the considered stations) were identified and grouped into 55 Saharan dust episodes. Analysis showed that DLV exceedances due to Saharan dust advection vanish at all stations when dust contributions are subtracted. A synoptic analysis based on the meteorological charts was carried out allowing a view of Saharan dust transport into Italy for each meteorological season. Notwithstanding that summer is the season most influenced by Saharan episodes at all of the stations, the analysis showed a low-high system of anomalies on the geopotential height distribution causing south-southwesterly flow carrying dust into Italy during the other seasons.

No abstract

Background: Rockfall events are one of the most dangerous phenomena that often cause several damages both to people and facilities. During recent years, the scientific community focused the attention at evaluating the effectiveness of seismological methods in monitoring these phenomena. In this work, we present a quick and practical method to locate the rebounds of some man-induced boulders falls from a landslides crown located in the Northern Apennines (Central Italy). The reconstruction of the trajectories was obtained by means of back analysis performed through a Matlab code that takes into account both the DEM (Digital Elevation Model) of the ground, the geotechnical-geophysical characteristics of the slope and the arrival times of the seismic signals generated by the rock impacts on the ground.