Fine-Mode Marine Aerosol Composition over the Southern Ocean Exampled by Individual Particle Analysis

During a cruise in the Southern Ocean in the austral summer of 2010-2011, the fine-mode aerosol particles (0.1 - 1.0 microns in diameter) were collected on a transect from 55S, 94E to 69S, 76E to characterize marine aerosols, as aerosol particles in that size fraction may effectively serve as cloud condensation nuclei and scatter solar radiation in the marine atmospheric boundary layer. Analyses of individual aerosol particles were performed by automated scanning electron microscopy. Preliminary results indicate that the main components of the aerosol particles examined so far include sodium chloride, calcium sulfate and aluminum oxide (alumina), and the great majority of the particles consist of these components or mixtures of these components. A small percentage of fine particles were detected to have minor Fe. The aerosol samples collected appeared to be impacted by air masses from the Antarctic Peninsula and Patagonia. The presence of fine Al-rich particles suggests transport from a source or sources in Patagonia, such as the complex at Puerto Madryn, Argentina. The presence of Al of industrial origin (and the lack of Al-rich silicates from soil dust) in these fine particles is of interest, since its presence in aerosols is sometimes used as a marker for dust. The possible impact of anthropogenic pollutant aerosols on this remote oceanic region is also striking.