Individual Antarctic aerosol particles in the 0.5#x2013;4 #x3BC;m aerodynamic diameter range were analyzed using laser microprobe mass analysis (LAMMA). As they were sampled near the ocean, the great majority consists of seasalt, transformed to various degrees in the atmosphere. Major alterations include the association of an excess sulfate and methane sulfonate with these particles. Sulfate-rich particles containing little or no chloride were found mostly in the smallest size fraction (0.5#x2013;1 #x3BC;m), where they account for some 5 of all particles: they are most likely highly transformed seasalt. Aluminosilicates, on the other hand, only appear among the coarser particles: they represent 2 of the particulates in the 2#x2013;4 #x3BC;m range. The remainder of the aerosol consists of organic, Fe-rich, K-rich and Zn-rich particles. The latter groups have very low abundances: always less than 1 of the population of the impactor stage(s) onto which they were collected.
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