Size distribution and probable sources of trace elements in submicron atmospheric particulate material

Size-segregated atmospheric particulate material was collected at a rural l ocation in the Great Smokey Mountain National Park, Tennessee, and at an ur ban site in Pasadena, California. The elemental composition of this materia l was determined by Instrumental Neutron Activation Analysis. Elements iden tified as being of anthropogenic origin had mass median diameters of below one micron, while elements of crustal origin were generally found to have a mass median diameters well over one micron. Some of the Pasadena samples h owever had elevated concentrations of the typical crustal elements Al, Fe, La, and Ce in the finer size fractions, probably due to motor vehicle emiss ions.