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.