RECEPTOR MODELING OF AIRBORNE IONIC SPECIES COLLECTED IN SCAQS

Source/receptor relationships for inorganic ionic species measured dur ing the Southern California Air Quality Study of 1987 have been invest igated using two receptor modeling techniques. The chemical species da ta were determined using ion chromatography (IC) (NO32-, SO42-, Cl-, S O2), colorimetry (NH3 and NH4+) and atomic absorption (AA) (PM 10 Na) on samples collected using the SCAQS samplers at three sites: Burbank, Claremont and Rubidoux. In order to compare these generally secondary particulate species with the behavior of primary particles emitted by sources in the South Coast Air Basin (SoCAB), X-ray fluorescence (XRF ) analytical results have been combined with the IC, colorimetry and A A results to provide the input data for principal component factor ana lysis. In general, there were only limited correlations between the se condary ionic species and the trace elements measured by XRF. The XRF results indicated the primary PM2.5 particles originated mainly from m arine and soil sources. The factors containing the acidic species were generally separated from those of the trace elements. The acidic spec ies data were combined with meteorological data in the form of air par cel back trajectories to produce conditional probability maps. This ap proach is called Potential Source Contribution Function (PSCF) analysi s. It was found that there was generally good correspondence between t he source areas identified by the PSCF maps and those provided in the emission inventory maps for NH3, SO(x) and NO(x).