(Table S1) Concentration of GLY and MGLY on marine aerosol particles, 24 hours sampling time from midnight to midnight (UTC) during POLARSTERN cruise ANT-XXVII/4

Aerosol particles were sampled using a high volume sampler equipped with quartz fiber filters. The aerosol sampler was installed on top of the observation deck (height ca. 30 m). The aerosol particle data represent clean marine conditions (air masses from the open sea, concentration of elemental carbon < 60 ng/m**3). From the aerosol particles inorganic ions and organic matter was measured. Particulate oxalic acid was determined with ion chromatography. The alpha dicarbonyls glyoxal (GLY) and methylglyoxal (MGLY) from marine aerosol particles were determined with an analytical method based on derivatisation with o-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine (PFBHA) reagent, solvent extraction and GC-MS (SIM) analysis.