Activities: - PM1 sampling by a High-Volume Sampler (TECORA eco-highvol equipped with digital PM1 sampling inlet, nominal flow 500 lpm) on pre-washed and pre-baked quartz-fiber filters (PALL, Ø= 18cm). Sampling time: 3-4 days per sample. - Off-line filter based AMS characterization of water soluble non-refractory sulfate, nitrate, ammonium, chloride, and organic mass (NR-PM1). - Off-line filter-based spectroscopic characterization of the water-soluble organic mass in term of chemical functional groups and specific markers by means of proton-Nuclear Magnetic Resonance spectroscopy (H-NMR). - Source apportionment of organic aerosol by means of multivariate statistical techniques (namely Positive Matrix Factorization, PMF, and other factor analysis methods) applied on both AMS and NMR spectral datasets. Available data: -NMR functional groups (Aromatics, anomeric/vynilic, H-C-O, H-C-C=, H-C) -NMR tracers: Levoglucosan, Methane-sulphonic acid (MSA), Hydroxymethane-sulphonic acid (HMSA), Amines (mono-, di- and tri-methyl amines, etc.) -HR-TOF-AMS (off-line): main species (Org, SO4, NO3, NH4, Chl), elemental ratios (OM:OC, O:C, H:C) & tracer fragments (m/z43, 44, 60 etc.) -NMR & AMS OA source apportionment

Aerosol sampling by a High-Volume Sampler (TECORA eco-highvol equipped with digital PM1 sampling inlet, nominal flow 500 lpm) for the collection of ambient aerosol particles with aerodynamic diameter < 1 μm (PM1) on pre-washed and pre-baked quartz-fiber filters (PALL, Ø= 18cm). Sampling time: 3-4 days per sample. A multi-technique analytical approach for the characterization of the sampled organic aerosol: Organic matter (OM) and Organic Nitrogen (ON). Analytical techniques employed are based on nuclear magnetic resonance spectroscopy (NMR) and Aerosol Mass Spectrometry (HR-TOF-AMS applied off-line) for the OM characterization, C and N elemental analysis (CN-EA) and ion chromatography (IC) for inorganic ions and alkyl-amines. -NMR functional groups (Aromatics, anomeric/vynilic, H-C-O, H-C-C=, H.C) -NMR tracers: Levoglucosan, Methane-sulphonic acid (MSA), Hydroxymethane-sulphonic acid (HMSA), Amines (mono-, di- and tri-methyl amines, etc.) -HR-TOF-AMS (off-line): main species (Org, SO4, NO3, NH4, Chl), elemental ratios (OM:OC, O:C, H:C) & tracer fragments (m/z43, 44, 60 etc.) -NMR & AMS OA source apportionment