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

Adelaide Dinoi,Sacha Moretti,Paolo Bonasoni,Daniel Gullì,Giuseppina Tirimberio,Elena Chianese,Claudia Calidonna,Daniela Cesari,Attilio Naccarato,Virginia Andreoli,Ivano Ammoscato,Daniele Contini,Angela Marinoni,Angelo Riccio,Francesca Sprovieri

doi:10.3390/atmos8120243

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 PM10 and PM2.5 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/m3) and Lecce (10.7 ± 5.8 and 9.0 ± 4.7 μg/m3), followed by Lamezia Terme (4.3 ± 2.0 and 4.0 ± 1.9 μg/m3), Capo Granitola (2.3 ± 1.2 and 1.7 ± 1.1 μg/m3), and Monte Curcio (0.9 ± 0.3 and 0.9 ± 0.3 μg/m3) in PM10 and PM2.5, 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/m3) and Lecce (1.5 ± 0.8 and 1.4 ± 0.7 μg/m3), followed by Lamezia Terme (0.6 ± 0.3 and 0.6 ± 0.3 μg/m3), Capo Granitola (0.3 ± 0.3 and 0.3 ± 0.2 μg/m3), and Monte Curcio (0.06 ± 0.04 and 0.05 ± 0.03 μg/m3) in PM10 and PM2.5, respectively. An opposite trend was observed for the OC/EC ratios ranging from 6.4 to 15.9 in PM10 and from 6.4 to 15.5 in PM2.5 with lower values in urban sites compared to remote sites. Different OC-EC correlations, 0.36 < R2 < 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/m3 in PM10 and from 0.4 to 7.2 μg/m3 in PM2.5, accounting from 37 to 59% of total OC in PM10 and from 40 to 57% in PM2.5 with higher percentages in the urban and suburban sites of Naples and Lecce.

Highlights

Carbonaceous aerosol components, organic carbon (OC) and elemental carbon (EC), account for a large fraction of atmospheric particulate matter (PM) and, on average, contribute to 20–45% of PM2.5 and 20–35% of PM10 [1,2] across Europe
The temporal variability of the PM10 and PM2.5 average daily concentrations measured during the campaign at all sites is plotted in Figure 2, while the statistics of the concentrations are shown in Table 1 which reports the average values (±standard deviation), minima (Min), maxima (Max), PM2.5 /PM10 average ratios, and the number of samples (N)
The higher PM10 and PM2.5 mass concentration values were observed in the urban site of Naples (50.8 ± 21.7 and 37.8 ± 18.0 μg/m3 ), followed by Lecce (32.7 ± 13.0 and 25.7 ± 11.6 μg/m3 ), Capo Granitola (23.2 ± 8.6 and 10.4 ± 2.6 μg/m3 ), Lamezia Terme (10.1 ± 3.8 and 7.2 ± 3.5 μg/m3 ) and Monte Curcio (3.4 ± 1.4 and 3.0 ± 1.2 μg/m3 )

Summary

Introduction

Carbonaceous aerosol components, organic carbon (OC) and elemental carbon (EC), account for a large fraction of atmospheric particulate matter (PM) and, on average, contribute to 20–45% of PM2.5 and 20–35% of PM10 [1,2] across Europe. Organic carbon originates from a variety of processes It can be released into the atmosphere from anthropogenic (fossil fuel combustion, domestic heating and cooking, industrial processes, biomass burning), and biogenic sources (vegetation, wind-lifted biological particles, fires, emissions from marine environments), as primary OC (POC), or produced within the atmosphere by photochemical reactions through gas-to particle conversion of volatile organic compounds, as secondary OC (SOC) [6,7,8]. Due to their different physical and chemical properties, OC and EC influence the environment and climate in different ways

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Conclusion