Characterization of PM10 and PM2.5 and Their Metals Content in Different Typologies of Sites in South-Eastern Italy

Samples of PM10 and PM2.5 were collected discontinuously between 2003 and 2010 at fifteen monitoring sites (urban, background, industrial) in the south-eastern part of Italy using a mobile laboratory. In total, 483 PM10 and 154 PM2.5 samples were collected and chemically analyzed for the determination of metal content. Data were used to investigate concentration differences among the typologies of sites, the seasonal patterns, and the influence of advection of Saharan dust (SD). PM10 and PM2.5 average concentrations increase from background to industrial and urban sites but the ratio PM2.5/PM10 is significantly lower (0.61 ± 0.10) in background sites. The average metals concentrations in PM10 and in PM2.5 do not show a clear dependence on site typology apart an increase in crustal elements in background sites and an increase in the enrichment factors of Ni and of Cr in PM10 in industrial sites. Urban sites show a statistically significant increase of PM10 average concentration during the cold seasons (autumn and winter), likely associated with the anthropogenic urban emissions, instead, the background sites show a decrease in concentrations during the cold seasons. This could be due to more frequent cases of SD observed in spring and summer periods that mainly influence background sites. The seasonal difference on the average concentration for industrial sites is not statistically significant. The SD cases influence both PM10 and PM2.5 concentrations but their effect is significantly larger on PM10. Over the studied area, the effect is relatively limited on long-term average PM10 (estimated increase of 3.2%) and PM2.5 (estimated increase of 1.5%) concentrations but it OPEN ACCESS Atmosphere 2014, 5 436 is significant on daily concentrations. It is estimated an increase of 22% of the probability to overcome the air quality standard daily threshold for PM10.