PM10 filter samples and polyurethane plugs, collected in the metropolitan area of Bologna (Italy) throughout 2002 and 2003, have been analysed for 9 polycyclic aromatic hydrocarbons (PAHs). Gas-particle partitioning coefficients KP were determined for all PAHs at various temperatures, and good log KP vs 1/T correlations were found, allowing us to estimate the heats of sorption of PAHs on PM10. Two linear log-log correlations were also checked; the former links KP and the subcooled liquid vapour pressures (pL o) with r2 = 0.88 and slope = -0.54. Slopes shallower than -0.6 indicate that absorption to the organic carbon (OC) microfilm coating particles is the prevailing sorption mechanism and that, by a molecular point of view, intermolecular interactions between PAHs and OC are smaller than intermolecular interactions in the pure liquid PAH. The second linear plot was found between KP and the octanol-air partition coefficients (KOA) with r2 = 0.89 and slope = 0.56. The last good fitting again confirms absorption on OC as the most important process, and indicates that chemical composition of particulate matter in the days examined keeps quite constant, thus reinforcing the hypothesis that a main atmospheric pollution source (vehicular traffic) is responsible for the air quality in the area of Bologna. © by PSP. 2006.

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