Five Years of Dust Episodes at the Southern Italy GAW Regional Coastal Mediterranean Observatory: Multisensors and Modeling Analysis

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

Investigation of reactive gases and methane variability in the coastal boundary layer of the central Mediterranean basin

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

Inter-comparison of carbon content in PM2.5and PM10collected at five measurement sites in Southern Italy

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 PM10and PM2.5samples 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 PM10and 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 PM10and PM2.5, respectively. An opposite trend was observed for the OC/EC ratios ranging from 6.4 to 15.9 in PM10and from 6.4 to 15.5 in PM2.5with 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/m3in PM10and from 0.4 to 7.2 μg/m3in PM2.5, accounting from 37 to 59% of total OC in PM10and from 40 to 57% in PM2.5with higher percentages in the urban and suburban sites of Naples and Lecce

Meteorology and air pollution at a coastal site - Experiment and modeling

Here we presents results of an experimental campaign performed in October 2016 in Ahtopol (Bulgaria) in the context of Exchange program between ISAC-CNR and NIHM-BAS research centers. The aim of the campaign is to collect aerosols in the coastal area, together with physical parameters; to consider air-masses circulation from meteorological output and to demonstrate that for some period Ahtopol and Lamezia Terme sites are in the same system. Evidence of aerosols circulation is also given by using HYSPLIT model for a better understanding of pollution sources also by chemical analysis form wet and dry deposition and filters from impactor

Particulate Matter Ionic and Elemental Composition during the Winter Season: A Comparative Study among Rural, Urban and Remote Sites in Southern Italy

We present an overview of the concentrations and distributions of water-soluble ion species and elemental components in ambient particulate matter for five measurement sites in southern Italy with the aim of investigating the influence of the different site characteristics on PM levels. The sites encompass different characteristics, ranging from urban to coastal and high-altitude remote areas. PM10 and PM2.5 fractions were collected simultaneously using dual channel samplers during the winter period from November 2015 to January 2016 and analyzed for water-soluble ion species, using ion chromatography, and elemental composition, using inductively coupled plasma mass spectrometry (ICP-MS). In all sites, PM2.5 represented the higher contribution to particulate mass, usually more than two times that of the coarse fraction (PM2.5−10). At the coastal site in Capo Granitola (Western Sicily), sea salts constituted about 30% of total PM10 mass. On average, ion species accounted for 30% to 60% of total PM10 mass and 15% to 50% of PM2.5 mass. We found that secondary ion species, i.e., SO2−4, NO−3 and NH+4 dominated the identifiable components within both PM2.5 and PM10 fractions. The chlorine–sodium ratio was usually lower than that expected from the natural level in sea salt, evidencing aged air masses. At the monitoring site in Naples, a highly urbanized area affected by high levels of anthropogenic source emissions, an increased contribution of ammonium was found, which was imputed to the increased ammonia emissions from industrial combustion sources and road traffic. The concentrations of the investigated elements showed noteworthy differences from one site to another. The PM10 fraction was highly enriched by sources of anthropogenic origin in the samples from the most urbanized areas. In general, the enrichment factors of the elements were similar between the PM10 and PM2.5 fractions, confirming common sources for all element

Meteorology and air pollution experiment at the Black Sea coastal site Ahtopol - 2017

Coastal dynamics is a challenging topic not only for physical processes capturing but also for phenomena related to aerosols exchange and transport. Here we present results of an experimental campaign performed in August 2017 at Ahtopol (Bulgaria) in the frame of Collaboration program between ISAC-CNR and NIMH-BAS research centers. The aim of the campaign was to carry out investigation of air pollution and meteorological conditions at Ahtopol coastal site through collecting aerosols, observing physical parameters, analyzing air-masses circulation and comparing the equipment and methods used by the participating groups. The observation programme of the experiment included measurements to capture both physical and chemical parameters and to reveal the near surface characteristics of sea breeze onset and penetration inland as well as its effect on the aerosol concentration. Particle concentration (number particles/liter in 6 different fractions) was measured with Aerosol and Laser Particle counters. In addition, samples of wet and total deposition were collected. Chemical analysis of collected wet and dry deposition samples and impacted filters was performed and the results obtained were compared with those of previous investigations