Year-round composition of bulk and size-segregated aerosol was examined at a coastal Antarctic site (Dumont d'Urville). Sea-salt particles display a summer depletion of chloride relative to sodium, which reaches ~10%. The mass chloride loss is maximum on 1- to 3-¿m-diameter particles, nitrate being often the anion causing the chloride loss. The summer SO42-/Na+ ratio exceeds the seawater value on submicron particles due to biogenic sulfate and on coarse particles due to ornithogenic (guano-enriched soils) sulfate and to heterogeneous uptake of SO2 (or H2SO4). HCl levels range from 47 ¿ 28 ng m-3 in the winter to 130 ¿ 110 ng m-3 in the summer, being close to the mass chloride loss of sea-salt aerosols. In the winter, sea-salt particles exhibit Cl-/Na+ and SO42-/Na+ mass ratios of 1.9 ¿ 0.1 and 0.13 ¿ 0.04, respectively. Resulting from precipitation of mirabilite during freezing of seawater, this sulfate-depletion-relative sodium takes place from May to October. From March to April, warmer temperatures and/or smaller sea ice extent offshore the site limit the phenomenon. A range of 14--50 ng m-3 of submicron sulfate is found, confirming the existence of nssSO42- in the winter at a coastal Antarctic site, highest values being found in the winters of 1992--1994 due to the Pinatubo volcanic input. Apart from these three winters, nssSO42- levels range between 15 and 30 ng m-3, but its origin is still unclear (quasi-continuous SO2 emissions from the Mount Erebus volcano or local wintertime dimethyl sulfide oxidation, in addition to long-range transported by-product of DMS oxidation).