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 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/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 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/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 PM_2.5, 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 PM_2.5 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 PM_2.5, accounting from 37 to 59% of total OC in PM₁₀ and from 40 to 57% in PM_2.5 with higher percentages in the urban and suburban sites of Naples and Lecce.

The Mediterranean area is a climate-change hotspot because of the natural and anthropogenic pollution pressure. The presence of natural aerosols, such as dust, influences solar radiation and contributes to the detection, in storm episodes, of significant concentrations of PM10 in Southern Italy, where generally fresh and clean air is due to local circulation, and particulate matter concentrations are very low. We present the results of medium-term observations (2015–2019) at Lamezia Terme GAW (Global Atmospheric Watch) Regional Observatory, with the purpose of identifying the dust incursion events by studying the aerosol properties in the site. To achieve this goal, the experimental data, collected by several instruments, have been also correlated with the large-scale atmospheric patterns derived by the ERA5 reanalysis dataset, in order to study the meteorological conditions that strongly influence dust outbreaks and their spatio-temporal behavior. An intense dust-outbreak episode, which occurred on 23–27 April 2019, was chosen as a case study; a detailed analysis was carried out considering surface and column optical properties, chemical properties, large-scale pattern circulation, air-quality modeling/satellite products, and back-trajectory analysis, to confirm the capability of the modeled large-scale atmospheric fields to correctly simulate the conditions mainly related to the desert dust-outbreak events.

We present a characterization of reactive gases (RG: O3, NO, NO2,SO2, CO) and methane (CH4) variability in the central Mediterranean basin,analyzing in situ measurements at three new permanent WMO/GAW Observatories in Southern Italy: Capo Granitola – CGR (Sicily), Lamezia Terme – LMT (Calabria) and Lecce – ECO (Apulia). At all the measurement sites, a combination of the breeze wind system (especially at CGR and LMT),PBL dynamics, anthropogenic/natural emissions, and photochemistry lead the appearance of well-defined diurnal cycles for the observed RG. According to O3/NOx variability, local emissions appeared to influence CGR and LMT (no NOx data were available for ECO during the period of study) in 4% and 20% of the hourly data, nearby sources in 39% and 40%, remote sources in 31% and 14%, while background O3/NOx were observed in 26% of cases for both the stations. Most of the background O3/NOx were observed during daytime, when offshore air masses usually affected the measurement sites. Local sources of CH4 at CGR can be related to biogenic (oxic) emissions from biomasses along the coastline, while emissions from live stocks can represent a local source of CH4 at LMT. Finally, we provide first hints about the export of O3 from Sicily/Southern Italy to the Mediterranean Sea by comparing simultaneous observations at CGR and Lampedusa (LMP), a small island in the middle of the Strait of Sicily where a WMO/GAW Regional Station is located. In summer,O3 increased by some 7 ppb for transport times lower than 48 h, while no statistical significant differences were observed for travel time longer than 48. This would suggest that photochemical O3 production occurred within air-mass travelling from CGR to LMP, but also that the central Mediterranean MBL represents a O3 sink for relatively aged air-masses.

In this work, results of scattering and backscattering coefficients, scattering Ångström exponent (SAE), single scattering albedo (SSA), and asymmetry parameter (g) of atmospheric aerosols are presented. All these parameters were measured during the month of April 2016 in Southern Italy on three different Global Atmosphere Watch observatories in the Central Mediterranean. This is the first time, to our knowledge, that optical aerosol properties were studied at the same time, even if in a brief intensive measurement campaign, at three sites in the South of Italy. In order to obtain a characteristic value for aerosol optical properties, different kinds of particle sources (i.e., dust, marine, and anthropic) have been identified and studied. In the measurement period, one event of a long-range transport of Saharan dust from Northern Africa was observed at all observatories. During the Saharan dust transport event, a minimum value of the SAE (0.69 ± 0.34) and a relatively higher values of SSA were observed. During the dust event, g increased up to 0.69. Marine aerosol contribution and anthropic/urban aerosol intrusion were analysed. From this analysis, SAE average values were 0.70, 0.84, and 1.22, respectively, for dust, marine, and anthropic particles. On the other hand, the SSA minimum value was 0.86 for anthropic particles, and it increased for dust (0.88) and marine (0.93) aerosols. The asymmetry parameter had a limited variability for the three types of aerosol from 0.62 to 0.58, as reported also in literature.