Non-target screening of a Siberian ice core reveals changes in the pre-industrial to industrial organic aerosol composition

Glaciers serve as natural archives for reconstructing past changes of atmospheric aerosol concentration and composition. While most ice-core studies have focused on inorganic species, organic compounds, which can constitute up to 90% of the submicron aerosol mass, have been largely overlooked. This study presents the first non-target screening record of secondary organic aerosol species preserved in a Belukha ice core (Siberia, Russian Federation), ranging from the pre-industrial to the industrial period (1800-1980 CE). 398 molecules, primarily polar and low-volatile compounds, were identified. Since the 1950s, a change in the atmospheric aerosol composition was observed, with the appearance of novel organic molecules, including nitrogen-containing compounds, deriving from enhanced atmospheric reactions with anthropogenic NOx, or direct emissions. Additionally, a significant increase in the oxygen-to-carbon ratio (+3%) and the average carbon oxidation state (+18%) of the detected molecules compared to the pre-industrial period was observed, suggesting an increased oxidative capacity of the atmosphere.