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

本研究项目调查的主要结果总结如下：形成高浓度SPM和PM_<2.5>的机制有两个：(1)活性光化学过程产生高浓度的OC和硫酸盐，导致颗粒中高浓度的（NH_4）_2SO_4，产生二次有机气溶胶；（ii）稳定的气象条件导致主要由车辆废气排放的初级颗粒积聚，造成高浓度的有机碳和有机碳。200m处的PM_<10>和PM_<2.5>均低于地面。以总颗粒质量与被测物种质量之和之差定义的“其他”物种在夏季的垂直质量浓度差异中占主导地位，而EC和OC是冬季的主要贡献者。同时观测到的相对湿度的垂直剖面表明，在地面采集的样品中，“其他”物种的浓度较高，可能是由于颗粒的潮解成分吸收了水分。研究了用小体积剥蚀器和滤包系统取样的半挥发性双功能羰基的气粒分布。比较埼玉县和目黑县的平均浓度，两处的乙醛酸浓度相似，但乙二醛、甲乙二醛和乙醇醛在目黑县的气相浓度较高，而在埼玉县的颗粒相浓度较高，这表明它们在运输过程中发生了气体到颗粒的转化。1995-2004年，用FRM采样器采集了酒井市区PM_<10>的日样，分析了其碳质成分。1995 ~ 2004年，TC、OC、EC的年平均浓度分别从13.7 μg-C/m^3、8.9 μg-C/m^3、4.8 μg-C/m^3下降到2.3 μg-C/m^3。1995 ~ 1998年OC浓度明显下降，2000 ~ 2004年EC浓度稳定下降。少

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