POTENTIAL SOURCE CONTRIBUTION FUNCTION-ANALYSIS AND SOURCE APPORTIONMENT OF SULFUR SPECIES MEASURED AT RUBIDOUX, CA DURING THE SOUTHERN CALIFORNIA AIR-QUALITY STUDY, 1987

During the Southern California Air Quality Study (SCAQS) in summer and fall of 1987, specially designed SCAQS samplers were used to collect particles and gaseous species. Ion chromatography (IC) and colorimetry were employed to analyze the gaseous and particulate ionic species wh ile the trace elements in the particles were analyzed using x-ray fluo rescence (XRF). Potential source contribution function (PSCF) analysis was applied to the chemistry data of the acidic species collected by the SCAQS samplers at the Burbank, Claremont and Rubidoux sites and th e meteorology data in the form of air parcel backward trajectories. Th e results are presented as gridded conditional probability maps showin g source areas that have a potential to contribute to the high concent rations of acidic species observed at the receptor sites. In order to quantitatively determine the mass contributions of acidic species from these identified source areas to the receptor sites, a source apporti onment method was developed that utilizes the PSCF analysis results an d the ground and elevated level emission inventories. One result is a gridded joint probability map showing the quantities of emitted acidic species from source areas that were transported to the three receptor sites with and/or without undergoing chemical transformations during the transport. Another result is a gridded map for each single recepto r site showing the possible maximum amounts of emitted acidic species from source areas that were transported to that receptor site with and /or without undergoing chemical transformations. The potential source areas identified by the PSCF analysis and the amount of transported em issions identified by the source apportionment method are generally we ll correlated with the emission inventories. The receptor modeling res ults of SO2 and SO42- are presented to illustrate the methodology.