New insights from seasonal and weekly evolutions of aerosol absorption properties and their association with PM2.5 and NO2 concentrations at a central Mediterranean site

Aerosol absorption parameters were investigated in this study using the measurements performed by an aethalometer during a monitoring campaign from December 2021 to July 2022 in a suburban area in south-eastern Italy. The aerosol absorption coefficient was compared to both PM2.5 and NO2 concentrations from two nearby stations (a rural and an urban site). Different seasonal evolutions were identified for these extensive parameters, even if they also showed a common feature because all these parameters presented a higher variability in winter due to the highly variable meteorological conditions during that season. Intensive parameters like the aerosol absorption Ångström exponent and the PM2.5/PM10 ratio were also investigated showing the effects of wood burning from domestic heating and of vehicular traffic, especially both in the urban and in the suburban site. Then, the weekly evolution of both selected extensive and intensive parameters was also analyzed to identify potential impacts due to the weekly cycle of human activities. Most of the selected parameters presented a significant increase starting from Tuesday to Friday and then they generally decreased during the weekends due to the relevant reduction of the human activities. The selection of different types of monitoring sites (urban, suburban, and rural) and temporal scales (seasonal and weekly) has been proved for a proper characterization of the aerosol absorption properties at the monitored area due to its geographical location at the center of the Mediterranean area.