Aerosol studies in the Karst of Trieste (Italy)

Regional air quality assessment and modeling of dynamics of gaseous and aerosol compounds can greatly benefit from experimental studies at sampling sites positioned in relative distance from intense sources of pollution; this is particularly valid in complex areas as the Karst, the limestone borderline plateau region extending in southwestern Slovenia and northeastern Italy, at some tens of kilometers from Trieste, a city of 210.000 inhabitants with an harbour, from the industrial town of Monfalcone with its 976 MW power plant and close to the Northern Adriatic Sea. A sampling site for aerosol and organic gases was established in Spring 2012 in close proximity to the entrance of the cave called Grotta Gigante, where also a meteorological station is working since 1967. The site lays in a submediterranean deciduous forest classified as Ostryo-Quercetum pubescentis. A day-night campaign was conducted in late June 2012 where ions, OC/EC and secundary organic compounds were measured, showing that the site is adequate to study BSOA formation from terpenes and isoprene precursors. Contrasts between summer and winter were studied with a series of four days samples, where ions, OC/EC, n-alkanes and PAHs were detected; markers from biomass burning as well as MSA, signing marine biogenic contribution, highlight the plurality of sources contributing at formation of aereosols. Recent XRF powder analysis contribute to mass closure, with information about inorganic composition. Experimental data are also compared with estimates from MEGAN model of emission of gas and aerosol from nature. Chemistry of wet and dry depositions has also started to be studied, aiming at characterizing inorganic inputs to soils.