Characteristics and source identification of roadside suspended particles

Suspended particles (TSP and PM10) are sampled on the weekend and on weekdays during four consecutive seasons. Water-soluble ionic species and metallic contents of suspended particles were further analyzed. Chemical analysis showed that the most abundant metals found in roadside suspended particles were Ca, Fe, and Al, while the most abundant ions were SO42-, NO3-, and NH4+. Field sampling of suspended particles indicated that TSP and PM10 concentrations in the daytime were higher than those at night. PM10 concentration on weekends was higher than on weekdays, while TSP concentration did not vary much between weekdays and weekend. PM10 was contributed by the long-distance transportation of non-traffic pollutants as well as the emissions of local road-traffic sources, while TSP related closely to the emissions of local road-traffic sources. Both approaches indicate that the major sources contributing to roadside suspended particles were vehicular emissions and fugitive road dust. However, the upwind non-traffic sources also contributed a noticeable portion of roadside suspended particles.