MEASUREMENT OF POLYCYCLIC AROMATIC-HYDROCARBONS ASSOCIATED WITH SIZE-SEGREGATED ATMOSPHERIC AEROSOLS IN MASSACHUSETTS

Size-segregated atmospheric aerosols were collected from urban and rur al locations in Massachusetts using a micro-orifice impactor. The samp les were analyzed for polycyclic aromatic hydrocarbons (PAH) with mole cular weights between 178 and 302, using gas chromatography/mass spect rometry. Fifteen PAH were quantified in the urban samples and nine in the rural samples. The quantification results are in good agreement wi th available ambient monitoring data. In the urban samples, PAH were d istributed among aerosol size fractions based on molecular weight PAH with molecular weights between 178 and 202 were approximately evenly d istributed between the fine (aerodynamic diameter <2 mu m) and coarse (aerodymanic diameter >2 mu m) aerosols. PAH with molecular weights gr eater than 228 were associated primarily with the fine aerosol fractio n. In the rural samples, low and high molecular weight PAH were associ ated with both the fine and coarse aerosols. Slow mass transfer by vap orization and condensation is proposed to explain the observed PAH par titioning among aerosol size fractions.