Influence of Intersection on Chemical Composition of Atmospheric Particulate Matters Observed at Roadside Environment in Urban Area

摘要

Atmospheric ultrafine particles (UFPs; Dp < 0.1 μm) and fine particles (FPs; Dp < 2.5 μm) are simultaneously collected for 11 h (daytime and nighttime) at four sites around one intersection in urban area. 14-day consecutive sampling was carried out to find the influence of intersection on the chemical composition of atmospheric UFPs and FPs, and to provide supportive data for possible emission of char or char-like particles from motor vehicles. Relative contribution of organic carbon (OC) and elemental carbon (EC) for total carbon (TC) in daytime samples accounts for 65 – 86% (UFPs: 83 – 86%, FPs: 65 – 75%) and 14 – 35% (UFPs: 14 – 17%, FPs: 25 – 35%) respectively whereas those in nighttime samples accounts for 71 – 90% (UFPs: 87 – 90%, FPs: 71 – 78%) and 10 – 29% (UFPs: 10 – 13%, FPs: 22 – 29%) respectively indicating high contribution of EC for the two particle sizes during daytime. Decreasing tendency of carbonaceous components was observed as the distance from intersection increases indicating strong influence of motor vehicles emissions around intersection. Furthermore, this study provides supportive data for possible char-EC emissions from motor vehicles around intersection.