Characterization of PM10 and PM2.5 source profiles for resuspended road dust collected using mobile sampling methodology

Abstract

Abstract A new sampling method using a mobile sampling system was developed to sample resuspended road dust on a paved road. To calculate the net mass concentration of resuspended road dust in the dust sample collected behind the front tire of the mobile sampling system, a background subtraction method was employed. The ratio of the PM 2.5 concentration to the PM 10 concentration in resuspended road dust ranged from 0.25 to 0.40, depending upon the sampling sites, which appears to be a function of traffic characteristics, land use, and so forth. The results of chemical analysis of PM samples demonstrated that specific source profiles for resuspended road dust exist according to sampling sites as well as particle size range. It is likely that, particularly in the case of Al, Ca, Fe, and OC, there exists a relatively small or approximately equal magnitude of dependence of sampling sites on the mass percentage of elements in the sampled PM compared with that of the particle size range. In view of the dependence of the Zn mass percentage and Cu/Sb on the average hourly traffic, it is clear that as traffic volume increases, tire wear and brake wear increase, and, accordingly, the amount of tire wear dust and brake wear dust deposited on paved roads increases. It turned out that OC and EC values do not change appreciably with the average hourly traffic. Nonetheless, it was noted that the OC values of PM coarse are two or three times larger than those of PM fine, showing a clear dependence of OC on the particle size range. In the case of EC, however, no clear dependence of EC on the particle size range was found.