Size-segregated aerosol samples were collected with a cascade impactor at 2 week intervals for a year at the research station Halley, situated near the coast in the Weddell Sea region of Antarctica. Sea salt is a major component of aerosol throughout the year, and we estimate that at least 60% of the total sea salt arriving at Halley is from brine and frost flowers on the sea ice surface rather than open water. Chloride in sea-salt particles is depleted relative to sodium in summer, consistent with loss of HCl as sea-salt particles react with gaseous acidic species, but is enhanced in large particles in winter because of fractionation occurring during the production of new sea ice. Non-sea-salt sulphate peaks in the summer, with the majority being in small particles indicative of a gas phase origin. The distribution of methane sulphonic acid closely follows that of non-sea-salt sulphate. In the winter, non-sea-salt sulphate is frequently negative, especially on stages collecting large particle sizes, consistent with the source of sea salt during the winter being predominantly the sea ice surface rather than open water. Nitrate peaks in the spring and summer and shows some association with sea-salt particles.