Diurnal Variation of Chemical Composition in Ultrafine and Fine Particles 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 23 h (1 day) and 11.5 h (daytime and nighttime) respectively in November when the contribution of biomass burning increases to observe characteristics of chemical composition in FPs in comparison with those collected for 23 h in UFPs. Contribution of biomass burning in FPs was found to be significant during the sampling periods especially in nighttime. Levoglucosan in UFPs was measure for the first time with that in FPs. The observed concentrations of levoglucosan in UFPs and FPs are highly correlated (r2 = 0.92, n = 10, p < 0.001) indicating that the observed levoglucosan in the two particle sizes had been originated from local biomass burnings close to the sampling sites. The simultaneous measurement of UFPs and FPs enabled us to find the emission sources (local or regional) in the study area. Negative correlation between organic carbon (OC) and soot-elemental carbon (EC) was observed for FPs collected at roadside while positive correlation between OC and soot-EC was observed for FPs collected at background site indicating different characteristics of carbonaceous components for different environment.