R8 AM Contamination Source Identification and Apportionment
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in 331-332

(TOT-1117-646586) Attempts to Identify Atmospheric PCB sources in the Philadelphia Metro Area.

Du, S¹, Totten, L¹, ¹ Rutgers University, New Brunswick, NJ, USA

ABSTRACT- The concentrations of polychlorinated biphenyls (PCBs) in the atmosphere in the Philadelphia metropolitan area (specifically at Camden, NJ and Swarthmore, PA), as measured by the New Jersey Atmospheric Deposition Network (NJADN), are elevated by as much as 20 times over regional background, averaging more than 3,000 pg per cubic meter. Because of these high levels, the loading of PCBs to the tidal Delaware River via via wet, dry, and gaseous atmospheric deposition exceeds the entire Total Maximum Daily Load (TMDL) recently established for PCBs. Identification of the sources of these atmospheric PCBs is therefore crucial to the implementation of the TMDL. Two models were used to identify atmospheric PCB sources in the region: A probabilistic model called the Potential Source Contribution Function (PSCF) which aims to identify source regions, and Positive Matrix Factorization (PMF), which identifies co-varying congener patterns. By itself, the PSCF model indicated that the major sources of PCBs to Camden lie to the west and south. Furthermore, the PSCF plots show high probabilities in the area within 50 km of the sampling site, indicating a strong local influence from Philadelphia metropolitan area. PMF analysis of the PCB concentration data yielded 4 co-varying congener patterns, which were tentatively identified based on the similarity of the congener pattern to known PCB sources. Combination of the two models indicated that the PMF factors may arise from different geographical regions around the Philadelphia metropolitan area.

Key words: PMF, PSCF, TMDL, Delaware