摘要: Atmospheric particulate samples were collected for a period of seven months using a 6-stage, cascade impactor at a ground level location 8 km from a large coal-fired power plant in the southwestern United States. One impactor was ... 展开 Atmospheric particulate samples were collected for a period of seven months using a 6-stage, cascade impactor at a ground level location 8 km from a large coal-fired power plant in the southwestern United States. One impactor was activated when ambient SO sub 2 concentrations exceeded a preset threshold of 64 mu g m exp -3 . This occurred 7% of the time. A second impactor was powered during other times. Meteorology and a lack of other sources of SO sub 2 at the sampling site combine to provide aerosol samples that represent the dispersed power plant plume and regional background. Elemental analyses for 32 elements were performed by instrumental neutron activation on these aerosols. The elemental concentration patterns were determined using statistical and pattern recognition procedures. The two sets of aerosol samples are characterized by different concentrations of chemical elements, particularly in the smaller (<3 mu m) sized particles. Most elements were present in higher concentrations in aerosols collected during high SO sub 2 periods than those obtained during low SO sub 2 periods. Three major patterns describe element concentration vs particle size behavior: (1) relatively constant concentrations in supermicron size particles, but much lower concentrations in submicron particles for aerosols collected during both high and low SO sub 2 periods, (2) increasingly higher concentrations as particle sizes decrease, regardless of SO sub 2 concentration (As, Br, Cl, Cu, I, In, Sb, Se, and W), and (3) elements exhibiting the first type of concentration vs size pattern during low SO sub 2 periods, but the second pattern during high SO sub 2 sampling periods. (ERA citation 06:020160) 收起