Development of The Carbon-Containing Aerosol Measuring Method and Elucidation of The Characteristic Property

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Major results investigated in this research project are summarized as shown below.Two mechanisms to induce high concentrations of SPM and PM_<2.5> were found : (i) an active photochemical process produced high concentrations of OC and sulfate, leading to a high concentration of (NH_4)_2SO_4 in the particles and to production of secondary organic aerosols ; (ii) stable meteorological conditions resulted in accumulation of primary particles, mainly emitted from vehicle exhaust, resulting in high concentrations of OC and EC.PM_<10> and PM_<2.5> collected at 200 m were lower than those collected on the ground. "Others" species defined as the difference between the total particle mass and the sum of the masses of the measured species dominantly accounted for the vertical difference in mass concentrations in summer, whereas EC and OC were the major contributors in winter. Vertical profiles of relative humidity observed simultaneously indicated that the higher concentrations of "others" speci … More es in the samples collected on the ground were probably caused by water having been absorbed by deliquescent components of the particles.Gas-particle distributions of semi-volatile bifunctional carbonyls sampled with a low-volume denuder and filter pack system were investigated. Comparing the average concentrations founded at Saitama and Meguro, glyoxylic acid concentrations were similar in both sites, though, glyoxal, methyl glyoxal and glycolaldehyde showed higher concentrations in the gaseous phase at Meguro and higher concentrations in the particulate phase at Saitama, suggesting a gas to particle conversion on their transport.Daily samples for PM_<10> were collected with FRM sampler during 1995-2004 at urban area in Sakai and analyzed for carbonaceous components. Yearly average concentrations during 1995-2004 decreased from 13.7 to 7.1μg-C/m^3for TC, 8.9 to 4.8 μg-C/m^3 for OC, and 4.8 to 2.3 μg-C/m^3 for EC. OC concentrations decreased considerably during 1995-1998 and steady decrease in EC concentrations was found during 2000〜2004. Less