Diurnal and seasonal characteristics of particle volatility and chemical composition in the vicinity of a light-duty vehicle freeway
Diurnal and seasonal characteristics of particle volatility and chemical composition in the vicinity of a light-duty vehicle freeway
复制标题
DOI：
10.1016/j.atmosenv.2005.08.025
复制
发表时间：
2005-12-01
影响因子：
5
通讯作者：
Sioutas, C
中科院分区：
文献类型：
--
作者：
Kuhn, T;Biswas, S;Sioutas, C
2005年冬季，在110号州际公路（美国加利福尼亚州洛杉矶的帕萨迪纳高速公路）附近，研究人员分析了粒径分级PM10颗粒的物理化学性质，这条轻型高速公路对重型车辆关闭。我们报告了超细颗粒在非常靠近高速公路和城市背景场地的粗、聚集和超细模式下的挥发性和化学特性。为了测量质量和化学成分，研究在每个位置使用了微孔均匀沉积冲击器（MOUDI）和改进的大容量采样器。两种仪器取样时的截点大小相同。在两个采样点使用串联差分迁移率分析仪（TDMA）来分析气溶胶的半挥发性部分。使用DMA测量了周围气溶胶的大小分布，使用冷凝粒子计数器（CPC）测量了总数浓度。这项研究是2004年夏季运动的延续，我们比较了这条高速公路附近PM特征的季节性变化，即冬季与夏季，以及昼夜变化，即白天与晚上。冬季晚高峰时段的交通状况与夏季最不一样，冬季的气温要低得多。观察到颗粒挥发性的日变化，在夜间采样的气溶胶中挥发性物质含量较高。颗粒数浓度在夜间也要高得多，从67,000 cm增加到110,000 cm（-3）。采样期间，高速公路旁的平均总浓度为80000 cm-3，高于夏季的46000 cm（-3）。对于40、80和120 nm的颗粒（39%的颗粒），观察到外部混合增加了非挥发性分数。总的来说，挥发性在晚上增加，而非挥发性部分减少。(c) 2005 Elsevier Ltd版权所有。
During the winter of 2005, physicochemical properties of size-fractionated PM10 particles were analyzed next to State Route 110 (Pasadena freeway in Los Angeles, CA, USA), a light-duty vehicle freeway, closed to heavy-duty traffic. We report volatility of ultrafine particles and chemical characteristics in the coarse, accumulation, and ultrafine modes very close to the freeway and at an urban background site. For measurement of mass and chemical composition, the study employed in each location a Micro-Orifice Uniform Deposit Impactor (MOUDI) and a modified high-volume sampler. Both instruments sampled with the same size cutpoints. A tandem differential mobility analyzer (TDMA) was used at the two sampling sites to analyze the semivolatile fraction of the aerosols. Size distributions of the ambient aerosol were measured using a DMA and total number concentration using a condensation particle counter (CPC).In this study, which was a continuation of a campaign during summer 2004, we compared the seasonal, i.e. winter versus summer, and diurnal, i.e. daytime versus evening, variation in PM characteristics in the vicinity of this freeway. Conditions in winter differed most from those in summer during the evening rush-hour traffic, with much lower temperatures in the winter campaign. Diurnal variations in particle volatility were observed, with higher content of volatile material in aerosols sampled in the evenings. Particle number concentrations were also much higher during the evening hours, increasing from 67,000 to 110,000 cm(-3). The average total number concentration next to the freeway was 80,000 cm-3 during the sampling period, which was higher than in summer, when the average was 46,000cm(-3). External mixing was observed with increasing nonvolatile fractions for 40, 80, and 120 nm particles (39% of particles). In general the volatility increased in the evenings, while the nonvolatile fraction decreased. (c) 2005 Elsevier Ltd. All rights reserved.