Exploring the Molecular Landscape of Organic Compounds in Aerosols and Seawater in the Arctic during spring and summer

The sensitive Arctic environment is affected by rapid climate change. Melting of glaciers and permafrost drives large changes in the transport of organic matter to the ocean, affecting e.g. macroalgae and phytoplankton. This also affects levels and chemical composition of atmospheric organic aerosols through formation of sea spray aerosols, as well as exchange across the sea-air interface of reactive volatile organic compounds, which are photochemically oxidized, forming products contributing to formation and growth of atmospheric aerosols. Aerosols influence climate through direct interaction with radiation and by affecting the formation and lifetime of clouds. Cloud feedbacks have both warming and cooling effects on the climate, however climate models for the Arctic region largely disagree about the direction of this feedback.

The presentation will provide an overview of our recent investigations of organic compounds in Arctic aerosols and dissolved organic matter (DOM) in Arctic seawater. 

Aerosols and seawater samples were collected in the Fram Strait during the ”Atmospheric rivers and the onset of Arctic melt” (ARTofMELT 2023) and at Disko Bay, Greenland (69°2'N, 53°3'W) during spring and summer 2023. Furthermore, aerosol samples were obtained from Villum Research Station (81.6oN, 16.7oW). After sample preparation, both aerosol and water samples were analysed using ultra-high-performance liquid chromatography coupled to high-resolution Orbitrap mass spectrometry (UHPLC-Orbitrap MS). 

Molecular tracers of biogenic secondary organic aerosols (BSOA) derived from isoprene and monoterpenes were quantified using authentic standards in all aerosol samples. The levels and composition of BSOA tracers provide insight into the origin of Arctic organic aerosols, from both regional sources and long-range transport. In one aerosol sample from Disko Bay, the concentration of BSOA was highly elevated due to long-range transport of air masses from the boreal zone. A series of dicarboxylic acids were also quantified in both aerosol and DOM to investigate the marine origin of these compounds. Furthermore, non-targeted analysis was employed to provide broader insight into the overall organic composition of both aerosols and DOM.

This work was supported by the Novo Nordisk Foundation, the Swedish Polar Research Secretariat, the Swedish Research Council (VR), the Knut and Alice Wallenberg Foundation, the Carlsberg Foundation, and the Danish National Research Foundation (DNRF 172) through the Center of Excellence for Chemistry of Clouds.