Aerosol Marine Primary Carbohydrates and Atmospheric Transformation in the Western Antarctic Peninsula

Abstract

We present ship-borne and land-based measurements of carbohydrate concentrations and patterns in (i) bulk seawater, (ii) sea surface microlayer (SML), and (iii) atmospheric size-resolved aerosol particles (0.05–10 μm) collected in the Western Antarctic Peninsula. In seawater, we find higher combined carbohydrates (CCHO) in both the particulate (PCCHO, 13–248 μg L–1) and dissolved (DCCHO, 14–294 μg L–1) phases than dissolved free carbohydrates (DFCHO, 1.0–17 μg L–1). Moderate enrichment factors are found in the SML samples (median EFSML = 1.4 for PCCHO, DCCHO, and DFCHO). In PM10 atmospheric particles, combined carbohydrates (CCHOaer,PM10 0.2–11.3 ng m–3) were preferably found in particles of two size modes (0.05–0.42 and 1.2–10 μm) and strongly correlated with Na+aer,PM10 and wind speed, hence suggesting oceanic emission as their primary source. In contrast to SML samples, very high enrichment factors for CCHOaer relative to the bulk water (EFaer) were estimated for supermicron (20–4000) and submicron (40–167 000) particles. Notably, the relative atmospheric aerosol monosaccharide compositions strongly differed from the ones sampled in seawater. The prevalence of bacterial monosaccharides (muramic acid, glucosamine) in aerosol particles allows us to suggest a selective consumption and release of polysaccharides by bacteria in the atmosphere. Our results highlight the need to evaluate the role of different ecosystems as aerosol sources around Antarctica