Simultaneous organic aerosol source apportionment at two Antarctic sites reveals large-scale and eco-region specific components

Antarctica and the Southern Ocean are the most pristine areas of the globe and represent ideal places to investigate aerosol-climate interactions in an unperturbed atmosphere. In this study, we present PM1 (Particulate Matter < 1µm) source apportionment for two sample sets collected in parallel at two British Antarctic Survey (BAS) stations, namely Signy and Halley, during the austral summer 2018-2019. We find that Water Soluble Organic Matter (WSOM) is a major aerosol component at both sites (average 25-33%). Remarkable differences between pelagic (open ocean) and sympagic (influenced by sea ice) air mass histories and related aerosol sources are found. The application of non-negative factor analysis techniques to H-NMR spectra of the samples allows the identification of five Organic Aerosol (OA) sources: two primary (POA) types, two secondary (SOA) types, and a fifth component of unclear origin possibly associated with the atmospheric ageing of primary emissions and dominating at Halley. Overall, the concentrations of primary and secondary organic aerosols are prevalently dictated by the emissions in sympagic and pelagic marine regions, with atmospheric circulation causing to establish marked latitudinal gradients only for some of such aerosol components. Our results strongly indicate that various sources and aerosols processes are controlling the Antarctic aerosol population, with the emissions from sympagic and pelagic ecosystems affecting the variability of submicron aerosol composition both in maritime areas as in inner Antarctic regions.

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