Sulfur and trace element concentration relationships in aerosols from the South American continent

Abstract

Sulfur concentrations in fine aerosol particles, aerodynamic diameter <1 µm, from nonurban coastal and inland locations in South America are generally lower than from locations in North America and the Western North Atlantic. In interior Brazil, sulfur is found exclusively in <1 µm particles, but a prominent fine particle mode of K, similar in size distribution to S, suggests a special source for both. Large scale combustion of forest materials may have enhanced fine mode S over levels characteristic of the undisturbed continental atmosphere. In the southeast trade winds submicrometer sulfur, which is less abundant than sulfur in >1 µm particles, does not comprise a distinct fine particle mode and may be accounted for by contributions from sea spray and an admixture of air from the interior. In the polar westerlies a similar particle size distribution of sulfur was found. If an upper limit is to be estimated for the concentration of a fine particle mode of sulfur in the “natural” atmosphere, it is less than indicated merely by total sulfur in the <1 µm diameter range.