Chemical compositions of size-resolved particles including nanoparticle fraction in roadside atmosphere were investigated. Particles were collected by low-pressure impactors, and carbonaceous components such as elemental/organic carbons (EC/OC), water-soluble ionic species, and elements were analyzed. Carbonaceous components accounted for about 90% (EC: 60%, Organics: 30%) of the particle fraction around 0.1 μm. Carbonaceous components still accounted for about 60% (EC; 30%, Organics: 30%) of sub-micron particles, but ionic species increased (30-40%) in this size. In coarse particles, elements were remarkable and carbonaceous species less contributed. On the other hand, carbonaceous components accounted for about 60% (EC: 40%, Organics: 20%) of nanoparticles (0.03-0.06 μm), and the percentage of elements were higher than that in the particles around 0.1 μm. In nanoparticles, major ionic species were SO_4~(2-)‘, NO_3ˉ, Clˉ and K~+, and NO_2~- was often detected at the same concentration level to those. Furthermore, Na, Mg, Si, P, S, Cl, K, and Ca were major elements in nanoparticles, and Ti, Cr, Pb and Hg were minor but commonly detected.
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