Characterization of seasonal sea-salt particles in Antarctica by the combined use of low-Z particle electron probe X-ray microanalysis and Raman microspectrometry

Abstract

Antarctica, having minimal influence from trade-winds, is isolated from cross-continental anthropogenic aerosol sources. Hence, it is one of the few pristine sites ideal for studying natural sea salt aerosols (SSAs) processes (Maskey et al., 2011). The different phases of natural SSAs significantly affect earth's radiative balance by scattering light and acting as cloud droplet or ice-nuclei (Ault et al., 2013). So far most investigations are based on artificially generated SSAs. This study aims to present a systematic examination of the interdependence of hygroscopic properties and the chemical heterogeneity of natural SSAs collected in the Antarctic. Aerosol samples were collected at a Korean scientific research station in the Antarctic: the King Sejong station (62º22'S, 58º78'W). Sea salt particles were collected on Al foils (Aldrich, 99.8% purity) using a three stage cascade impactor (PM10 Impactor, Dekati Inc.) in different seasons. The impactor has aerodynamic cut-offs of 10, 2.5, and 1 μm for stages 1, 2, and 3, respectively, at a 10 L min-1 sampling flow. The chemical compositions, mixing states, and spatial distribution of chemical species within individual particles are obtained by the combined use of low-Z particle energy-dispersive X-ray microanalysis and Raman microspectrometry.