Dissolved and particulate carbohydrates in MOSAiC seawater samples

Seawater samples were collected from CTD rosette casts at various depths during legs 1, 3, 4, and 5 of the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition. The following carbohydrate fractions were analyzed: dissolved free carbohydrates (DFCHO), dissolved combined carbohydrates (DCCHO), and particulate combined carbohydrates (PCCHO). DFCHO and DCCHO were determined from seawater filtered through 0.2 µm filters. Samples were desalinated by electrodialysis and analyzed using high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), following Zeppenfeld et al. (2020). PCCHO was measured from material retained on 0.2 µm polycarbonate membrane filters. DFCHO was measured directly, whereas DCCHO and PCCHO were quantified after acid hydrolysis. All fractions (DFCHO, DCCHO, PCCHO) were quantified as the sum of their constituent monosaccharides.We thank all Polarstern scientists and crew involved in seawater sampling during MOSAiC, with special thanks to the scientists of the ECO team.