Inter-Comparison of Carbon Content in PM2.5 and PM10 Collected at Five Measurement Sites in Southern Italy

Abstract

A field campaign was performed simultaneously at five measurement sites, having different characteristics, to characterize the spatial distribution of the carbonaceous content in atmospheric aerosol in Southern Italy during the winter season. Organic carbon (OC) and elemental carbon (EC) were measured at urban (Naples), suburban (Lecce), coastal/marine (Lamezia Terme and Capo Granitola), and remote (Monte Curcio) locations. OC and EC mass concentrations were quantified by the thermal-optical transmission (TOT) method, in 24-h PM 10 and PM 2.5 samples collected on quartz fiber filters, from 25 November 2015 to 1 January 2016. The different sites showed marked differences in the average concentrations of both carbonaceous species. Typically, OC average levels (±standard deviation) were higher at the sites of Naples (12.8 ± 5.1 and 11.8 ± 4.6 µg/m 3 ) and Lecce (10.7 ± 5.8 and 9.0 ± 4.7 µg/m 3 ), followed by Lamezia Terme (4.3 ± 2.0 and 4.0 ± 1.9 µg/m 3 ), Capo Granitola (2.3 ± 1.2 and 1.7 ± 1.1 µg/m 3 ), and Monte Curcio (0.9 ± 0.3 and 0.9 ± 0.3 µg/m 3 ) in PM 10 and PM 2.5 , respectively. Similarly, EC average levels (±standard deviation) were higher at the urban sites of Naples (2.3 ± 1.1 and 1.8 ± 0.5 µg/m 3 ) and Lecce (1.5 ± 0.8 and 1.4 ± 0.7 µg/m 3 ), followed by Lamezia Terme (0.6 ± 0.3 and 0.6 ± 0.3 µg/m 3 ), Capo Granitola (0.3 ± 0.3 and 0.3 ± 0.2 µg/m 3 ), and Monte Curcio (0.06 ± 0.04 and 0.05 ± 0.03 µg/m 3 ) in PM 10 and PM 2.5 , respectively. An opposite trend was observed for the OC/EC ratios ranging from 6.4 to 15.9 in PM 10 and from 6.4 to 15.5 in PM 2.5 with lower values in urban sites compared to remote sites. Different OC-EC correlations, 0.36 < R 2 < 0.90, were found in four observation sites. This behavior suggests the contributions of similar sources and common atmospheric processes in both fractions. No correlations were observed between OC and EC at the site of Naples. The average secondary organic carbon (SOC) concentrations, quantified using the minimum OC/EC ratio method, ranged from 0.4 to 7.6 µg/m 3 in PM 10 and from 0.4 to 7.2 µg/m 3 in PM 2.5 , accounting from 37 to 59% of total OC in PM 10 and from 40 to 57% in PM 2.5 with higher percentages in the urban and suburban sites of Naples and Lecce.

Characterization of In Situ Aerosol Optical Properties at Three Observatories in the Central Mediterranean

“…In the CGR observatory (Figure 3a), the average fine mode number concentration was 29.2 ± 20.8 particles (#) cm −3 , while coarse particle number concentration was 1.6 ± 0.8 # cm −3 with a mean relative ratio 5.5%. This ratio is representative of a rural environment with sporadic intrusion of anthropic pollution [37]. At the LMT site (Figure 3b), the mean fine and coarse mode number concentration were, respectively, 7.3 ± 4.8 # cm −3 and 0.5 ± 0.4 # cm −3 with an average relative ratio of 7.2%.…”

Airborne Particles during a Firework Festival in Belvedere M.mo, South-Western Italian Coast

“…The only nearest sampling site with air quality data collected in the same period of our study is the Lamezia station. This coastal site faces on the Tyrrhenian Sea and is located at about 80 km SSW in respect to Belvedere M.mo [37]. During the same sampling period of our observations at Belvedere, the values recorded at Lamezia station for PM 2.5 were even lower than 10 μg•m −3 [43].…”

“…EC concentrations observed in blank filters were negligible; however, contamination was observed for OC with an average correction that was about 7%. In this study, the SOC concentration was additionally quantified using the minimum OC/EC ratio methodology proposed by [31]- [37]. …”

Carbonaceous Aerosols in the Atmosphere

“…This is the case of the Mediterranean basin-one of the most fragile climatic zones on the planet, which is impacted by anthropogenic emissions, biomass burning, and natural sources (e.g., marine emissions and Saharan dust events)-where the paucity of OC and EC data is especially observed in the southern part of the Italian peninsula. The study by Dinoi et al [43] reports results of a field campaign on EC and OC measurements carried out during wintertime 2016 at five different sites in Southern Italy. Urban, suburban, coastal/marine and remote locations were selected to map the spatial distribution of EC and OC on both PM 10 and PM 2.5 applying the same experimental approach in order to avoid biases due to differences in the thermal protocols used to quantify the two carbonaceous fractions.…”