Interactions of Anthropogenic and Biogenic Pollutants: Overview of the Spruce 2022 Campaign

ANGELIKI MATRALI, Christina N. Vasilakopoulou, Kalliopi Florou, Andreas Aktypis, Agata Kołodziejczyk, Christos Kaltsonoudis, Evangelia Kostenidou, Kacper Błaziak, Dontavious Sippial, Spyros Ν. Pandis, University of Patras, Greece

     Abstract Number: 163
     Working Group: Aerosol Chemistry

Abstract
The SPRUCE-22 field campaign was conducted during July 2022, on a remote mountainous forested site in Greece to quantify the interactions of biogenic and anthropogenic pollutants in the Eastern Mediterranean. Particle chemical composition and size distributions along with VOCs and other gases were measured at high temporal resolution using state-of-the-art instrumentation (AMS, PTR-MS, SP₂, etc.), while samples were collected and analyzed off-line (HP-LC, XRF, GC-MS, ¹⁴C, oxidative potential, etc.). Dual smog chamber experiments were performed to investigate the chemical aging of the PM.

PM₁ had a surprisingly high average concentration of 12.7 μg m^-3 consisting primarily of organics (57%), followed by sulfate (30%) ammonium (9%), and black carbon (2%). Nitrate levels (both inorganic and organic) were less than 1% of the fine PM despite the relatively high NO_x emissions in the Balkans. The PM_2.5 daily concentrations at this remote site were similar and even higher than those in major cities across Greece including Athens, indicating the importance of regional transport for summertime pollution in this area. The relatively constant average diurnal profiles of major anthropogenic pollutants (black carbon, NO_x, aromatic VOCs, etc.) are consistent with the lack of local sources. Sulfates were not any more the dominant component of fine PM due to the reduction of SO₂ emissions by coal-burning powerplants. The organic aerosol (OA) was quite oxidized with average oxygen to carbon ratio (O:C) equal to 0.83. The average isoprene concentration was 0.6 ppb, of the monoterpenes 0.5 ppb, and biogenic SOA was estimated to contribute 24% of the OA. The biogenic SOA was quite aged (O:C equal to 0.63) and the mobile dual smog chamber experiments suggested that additional aging was rather slow. Local nucleation events were scarce. The source attribution of the fine PM and the interactions among its anthropogenic and biogenic components are discussed.