Chemical characteristics and origins of nitrogen-containing organic compounds in PM2.5 aerosols in the Lower Fraser Valley.

ABSTRACT

Some nitrogen-containing organic compounds (NOCs) in PM2.5 aerosols in forest, tunnel, urban, rural, and mixed forest/ urban areas in the Lower Fraser Valley (LFV), British Columbia, Canada, were measured to assess their chemical characteristics, temporal and spatial distributions, and origins. The levels of E-caprolactam, isoindole-1,3-dione, benzothiazolone, and N-butyl-benzensulfonamide showed significant differences among the sites, with the highest level at the mixed forest/urban site, indicating that aerosols at this site were impacted by chemical manufacturing activities. N,N-diethyl-m-toluamide (deet) was detected at all locations but was highest in the forest area, demonstrating a widespread usage as an insect repellent in the LFV and at camps at the forest site. Alkyl amides, tracers from wood burning and cooking, ranging from C6 to C20 including two unsaturated amides, hexadecenamide, and 9-octa-decenamide, were detected at all sites. Three patterns of carbon number distributions of alkyl amides varied with location and time, and were mainly impacted by biomass burning or cooking compared to levoglucosan and cholesterol in the LFV. Ratio of oleamide to stearamide (C181/C180) was discussed as a potential indicator for determining "age" or transport range of biomass combustion plumes.