Seasonal features of ultrafine particle volatility in the coastal Antarctic troposphere

The size distribution and volatility of ultrafine aerosol particles were measured using scanning mobility particle sizer and thermodenuder at Syowa Station during the 46–47 Japanese Antarctic Research Expeditions (2005–2007). The relative abundance of non-volatile particles in a 240 °C scan was approximately 20% during the summer, whereas the abundance of non-volatile particles increased by >90% during the winter–spring. Most ultrafine particles were volatilized at temperature of 150–210 °C. This volatility was consistent well to major aerosol constituents (NH4+, SO42− and CH3SO3−) during the summer. In contrast, major constituents of ultrafine particles were sea-salts (Na+ and Cl−) in winter–spring. Therefore, the seasonal feature of volatility of ultrafine particles at Syowa was associated with seasonal variations of the major aerosol constituents. Although the relative abundance of non-volatile particles was usually higher during the winter–spring, the abundance dropped occasionally to <30%. The lower abundance of non-volatile ultrafine particles during winter–spring corresponded to the lower number concentration of ultrafine particles and transport from the free troposphere over Antarctica.