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

(MIN-1117-833741) Characterization of PAH composition patterns in diesel emissions.

Minegishi, T¹, Crimmins, B¹, Baker, J¹, ¹ University of Maryland Chesapeake Biological Laboratory, Solomons, MD, USA

ABSTRACT- Polycyclic Aromatic Hydrocarbons (PAHs) have been used to characterize the proportion of emission sources to ambient aerosol concentrations. Source apportionment using PAHs has separated coal, wood combustion, oil, and vehicle emissions. Positive Matrix Factorization (PMF) was the only multivariate method that could separate diesel and gasoline sources in ambient air samples from Baltimore, MD (Larsen, 2003). The purpose of this study was to characterize the PAH composition of diesel emissions in order to better distinguish between diesel and gasoline signals. Samples were collected adjacent to idling trucks at truck stops as well as field sites nearby interstate highways. Diesel emission was the dominant signal at the truck stop, and the field site consisted of a mixture of gasoline and diesel inputs. Preliminary results from Knoxville, TN showed that although the PAH concentration profiles were very similar, statistical analysis using Principal Component Analysis (PCA) separated the truck stop and highway samples. The variables contributing to the separation were dibenz[a,h+a,c]anthracene, benzo[a]pyrene, and chrysene+triphenylene for the truck stop, and 2-methyldibenzothiophene, 1-methylfluorene, and fluorene for the highway. There also appeared to be a separation between day and night samples. The variables contributing to this diurnal separation were benzo[a]fluorene, benzo[b]fluorene, and 3,6-dimethylnaphthalene for night (7am-7pm), and 1,5-Dimethylnapthalene, Napthacene, and Acenapthacene for day (7am-7pm). Diesel emissions collected from different locations under different conditions are being used to characterize a comprehensive PAH pattern for diesel emission.

Key words: PAH, diesel, aerosol