DOI: 10.5061/dryad.n02v6wx66
title: Non-target screening of a Siberian ice core reveals changes in the pre-industrial to industrial organic aerosol composition

description: 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.
description: # Non-target screening of a Siberian ice core reveals changes in the
 pre-industrial to industrial organic aerosol composition
 [https://doi.org/10.5061/dryad.n02v6wx66](https://doi.org/10.5061/dryad.n02v6wx66) ## Description of the data and file structure Sampling site, sample processing, and labware cleaning procedure A 163-m long ice core reaching bedrock was collected using an electromechanical drill at Belukha glacier (4062 m. a.s.l. - 49°48’26” N, 86°34’46” E) between 27 May and 10 June 2018. The core was drilled around 90 m NE of the 2001 drill site (B01) (*76*). After being collected, all cores were sealed in polyethylene (PE) tubes in the field and stored in insulated boxes. All samples were shipped frozen to Paul Scherrer Institut (Switzerland) and stored at -20°C until analysis. The samples analyzed in this study (n = 53) cover the time period 1800-1980 CE, i.e., from to 62.87 to 26.55 m-depth. Samples had a density ≥ 0.7 g cm-3, thus minimizing risks for external contamination that can occur when porous material, such as firn, is analyzed. Extraction and mass spectrometric analysis Water-soluble organic tracers were extracted and analyzed following the methodology described in Burgay et al., (*39*). In brief, samples were enriched by a factor 92 ± 3 using strong anionic exchange solid-phase extractions (SPE) cartridges (MAX, Waters) and analyzed using Ultra-High Performance Liquid Chromatography (Ultimate 3000, Thermo Fisher Scientific) equipped with an AcclaimTM Organic Acid Column (3 µm, 2.1 x 150 mm, Thermo Fisher Scientific, operated at 50°C) coupled with High-Resolution Mass Spectrometry (UHPLC-HRMS, Q Exactive Focus, Thermo Fisher Scientific). This setup allowed an optimal ionization efficiency and chromatographic separation for the class of compounds of interest, i.e., secondary organic aerosol tracers, such as carboxylic acids, while it is not suitable for the complete analyses of S-containing molecules, due to their high diversity (e.g., sulfides, thiophenes or polyaromatic sulfur heterocycles) that require other pre-analytical and analytical conditions. More details are provided in the main publication and on the supplementary material ### Files and variables #### File: Dataset\_Belukha.xlsx **Description:** In this dataset, details regarding the molecular formula, the temporal profiles for the different compound classes as well as changes in their oxidation state are reported. ##### Variables * Molecular formulas (Sheet: "Molecular formulas") * Mass-to-charge (m/z) ratio of the identified molecular formulas(Sheet: "Molecular formulas") * Retention times (RT) of the identified molecular formulas (Sheet: "Molecular formulas") * Average corrected intensity of the identified molecular formulas (Sheet: "Molecular formulas") * Nitrate concentration in ppb between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg") * Sulphate concentration in ppb between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg") * Ozone concentration in ppb  between 1850 and 1980. n/a = data not available (Sheet: "Belukha*Icecore*data*5yr*avg") * OH radical concentration in molec cm-3  between 1850 and 1980. n/a = data not available  (Sheet: "Belukha*Icecore*data*5yr*avg") * Aggregated profile of molecules containing C, H, O between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg") * Aggregated profile of molecules containing C, H, N, O  between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg") * Aggregated profile of molecules containing C, H, N, O, S  between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg") * Aggregated profile of molecules containing C, H, O, S  between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg") * Aggregated profile of molecules having other atomic compositions  between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg") * z-score for clusters 1, 1A, 1B, and 2  between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg") * Weighted average O/C ratio, weighted average average Carbon oxidation State (OSC,av) and weighted average number of carbon (nC)  between 1805 and 1980  (Sheet: "Belukha*Icecore*data*5yr*avg")