Investigation of particulate matter collected during three cruise campaigns in the Mediterranean Sea: composition and source apportionment

Due to its unique geographic position and its peculiar meteo-climatic conditions, Mediterranean basin appears to be an area with a relevant pollution load [1,2]. Natural sources such as Saharan dust, volcanoes, and fires, as well as anthropogenic sources, including dense ship traffic and highly industrialized sites, account for the increase of pollutant levels in the atmosphere [2,3]. The transport of both natural dust and anthropogenic aerosols into the marine environment is becoming of primary concern for its potential impact on marine ecosystems, world climate, and air quality. In the framework of the ongoing MED-Oceanor program funded by the Italian National Research Council (CNR) [4], marine aerosol measurements were performed to gain more insight into the atmospheric dynamical and chemical mechanisms that lead to high particulate matter (PM) levels over the Mediterranean Sea. PM2.5 and PM10 fractions were simultaneously collected during three cruise campaigns performed in autumn 2011, summer 2012, and summer 2015, along different routes covering the western Mediterranean sector. The study herein presented introduces the new insights gained from collected data. The sampling covered a broad range of atmospheric conditions, which included clean air above the calm sea, sea spray saturated days due to heavy sea, desert dust intrusion, and marine air affected by the emissions coming from large cities, industrialized areas, and biomass burning smoke plume. The particulate samples were analyzed by Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) to quantify major and trace elements. Particulate mass concentration showed quite a high variability, ranging from 10.5 to 38.8 ?g m-3 for PM10, and from 5.5 to 29.7 ?g m-3 for PM2.5. This dataset was analyzed by using the enrichment factors and pattern recognition approaches for source apportionment investigation.