Seasonality of aerosol chemical composition at King Sejong Station (Antarctic Peninsula) in 2013

Abstract

Seasonal variations of ionic species concentrations in PM10 and PM2.5 aerosols were investigated at King Sejong Station (King George Island, Antarctic Peninsula) in 2013. Seasonal variations of PM2.5 mass were also determined, and found to be in the range: 2482.2 ± 944.4 ng m−3 (austral winter) to 3493.3 ± 1223.8 ng m−3 (austral fall). On a weight basis, the PM2.5 ionic species consisted mainly of primary ions from sea spray (~30% in summer, ~50% in winter) and partly from secondary ions (~20% in summer), with the ratios of sea spray and secondary ion components to PM2.5 mass showing clear seasonal variation. The seasonal cycle of sea spray components was not well defined, but was weakly correlated with wind speed (r2 = 0.38). This correlation was likely attributable to a combination of the seasonal properties of wind and the measurement site's location at the western tip of Barton Peninsula. The concentrations of sulphur species (CH3SO3− and non sea salt SO42−) were clearly higher during austral summer. Notably, these concentrations were ~2–3 times higher during in January 2013 than in other summer months of the field observation period. This was attributed to an increased biomass of algae in the ocean area surrounding King George Island and more frequent air mass passage over ocean areas with algae blooms. The NH4+ concentration was also clearly higher in austral summer 2013, mainly due to secondary formation from the NH3 released from local emission sources such as penguin colonies and ocean areas near the measurement site with acidic aerosol, but also affected by local meteorology specific to the summer of 2014.