Six-Month Lasting Observations of Submicron Non-Refractory Aerosol Particles by Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM) at CIAO (Potenza, Italy)

As part of the ACTRIS research infrastructure, a six-month study (May–October 2024) was conducted at the CNR-IMAA Atmospheric Observatory (CIAO, Southern Italy) to characterize non-refractory submicron aerosol (NR-PM1). Measurements were conducted in real time using a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) and highlighted the predominant presence of organic aerosol (OA), with values reaching 49.5 µg m−3. During the study period, nitrate and ammonium concentrations remained below 2 µg m−3 on average, while sulfate concentrations showed normal variation during the analysis period (maximum value of 11.70 µg m−3). The daily variability of concentrations was influenced by both boundary layer dynamics and local emission variations. The calculated charge and mass balances allowed us to study the good neutralization of PM1 in the atmosphere. The composition of the organic aerosol was dominated by oxygenated species, with a small contribution from biomass combustion. Ultimately, these results provide an excellent starting point for understanding the aerosol chemical composition and seasonal variability at the site, ahead of future analyses and comparisons within the ACTRIS of which the observatory is part.