Mineralogical composition of aerosols at Amsterdam Island

In this paper, data on the mineralogical composition of insoluble particulate matter collected in May, July and September 1984 at Amsterdam Island, South Indian Ocean (34°47’S, 77°31’E) are presented for the first time. Atmospheric levels of these insoluble aerosols remain very low (from 0.25 to 0.01 μg m^-3); the size of the particles is mainly in the submicronic range. The long-range continental origin of these particles is well confirmed by atmospheric tracers such as ²²²Rn and ²¹⁰Pb and by air mass back-trajectories. Continental inputs, mainly from South Africa and Madagascar, that can be identified by “radonic storms” have a high illite/kaolinite ratio. However those from Australia, though less frequent at Amsterdam Island, have a low illite/kaolinite ratio. Thus, kaolinite can be considered a good tracer of transport of Australian aerosols into the subantarctic.