Analytical study on the primary and secondary organic carbon and elemental carbon in the particulate matter at the high-altitude Monte Curcio GAW station, Italy

This study provides a thorough investigation of the trends of organic carbon (OC) and elemental carbon (EC) in particulate matter (PM)(10) and PM2.5 samples collected at the Monte Curcio Observatory (1780 m a.s.l.), a station of the Global Atmosphere Watch (GAW) program and Global Mercury Observation System (GMOS) network. Although the drawn attention toward these pollutants, there is still a lack of data for southern Italy, and this work is a contribution toward the filling of this gap. PM was sampled daily in 2016 and analyzed by thermo-optical transmittance method, while equivalent black carbon (eBC) concentrations in PM10 were simultaneously measured using a multiangle absorption photometer. The results showed that in PM10, the average values of OC and EC were 1.43 mu gC/m(3) and 0.12 mu gC/m(3), whereas in PM2.5, these concentrations were 1.09 mu gC/m(3) and 0.12 mu gC/m(3), respectively. We detected a clear seasonal variability in OC and EC with higher concentrations during the warm period. Moreover, the analysis of the OC/EC ratio revealed that most of the carbonaceous aerosol was transported by long-range air masses, as further confirmed by the use of the concentration-weighed trajectory (CWT) model. The mass absorption cross-section at 632 nm of EC (MAC(EC)) over the entire period was 9.67 +/- 4.86 m(2)/g and 8.70 +/- 3.18 m(2)/g in PM2.5 and PM10, respectively, and did not exhibit a clear seasonal variation. The concentrations for OC and EC were also used for the computation of the secondary organic carbon (SOC) content, whose outcomes resulted in a seasonal trend similar to those obtained for OC and EC. As regards the eBC, its weekly pattern showed a slight increase during the weekend in the warm period, consistent with the anthropic activities in the touristic area surrounding the observatory.

Automated summary

This study thoroughly investigates the trends of organic carbon (OC) and elemental carbon (EC) concentrations in particulate matter samples collected at the Monte Curcio Observatory in southern Italy. The results show a clear seasonal variability in OC and EC concentrations, with higher levels during the warm period. The study also reveals that most of the carbonaceous aerosol is transported by long-range air masses.