Winter and summer time size distributions and densities of traffic-related aerosol particles at a busy highway in Helsinki
Winter and summer time size distributions and densities of traffic-related aerosol particles at a busy highway in Helsinki
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DOI：
10.5194/acp-6-2411-2006
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发表时间：
2006-06
影响因子：
6.3
通讯作者：
A. Virtanen;T. Rönkkö;J. Kannosto;J. Ristimäki;J. Mäkelä;J. Keskinen;T. Pakkanen;R. Hillamo;L. Pirjola;K. Hämeri
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文献类型：
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作者：
A. Virtanen;T. Rönkkö;J. Kannosto;J. Ristimäki;J. Mäkelä;J. Keskinen;T. Pakkanen;R. Hillamo;L. Pirjola;K. Hämeri
在两次冬季活动（2003年2月10日至26日、2004年1月28日至2月12日）和两次夏季活动（2003年8月12日至27日、2004年8月6日至20日）期间，在赫尔辛基路边测量了与交通相关的气溶胶颗粒的数量浓度和尺寸分布。测量是在距离高速公路 9 m 和 65 m 的地方同时进行的。总数浓度通过冷凝粒子计数器（CPC）测量，粒度分布通过扫描迁移粒度仪（SMPS）和低压电冲击器（ELPI）测量。本研究集中于风向从道路到测量地点时测量的数据。冬季总浓度是夏季的2-3倍，且浓度以成核模式粒子为主。小于 63 nm（空气动力学直径）的颗粒物在冬季约占所有颗粒物的 90%，在夏季约占所有颗粒物的 80%。颗粒物总浓度随着交通流量的增加而增加。流量速率对小于 63 nm 的颗粒的影响强于对较大颗粒的影响。路边的颗粒分布由两种可区分的模式组成。成核模式（模式1）的几何平均直径（GMD）夏季为20.3 nm，冬季为18.9 nm。主要由交通相关烟尘颗粒组成的较大模式（模式 2）的 GMD 在夏季为 72.0 nm，在冬季为 75.1 nm。模式的 GMD 值不依赖于流量速率。每种模式的平均颗粒密度是通过基于 ELPI 和 SMPS 进行的尺寸分布测量的并行密度拟合方法确定的。夏季和冬季模式1颗粒的平均密度值分别为1.0±0.13 g/cm 3 和1.0±0.07 g/cm 3 ，而模式2夏季和冬季的平均密度值分别为1.5±0.1 g/cm 3 和1.8±0.3 g/cm 3 。
Number concentrations and size distributions of traffic related aerosol particles were measured at a roadside in Helsinki during two winter campaigns (10–26 February 2003, 28 January–12 February 2004) and two summer campaigns (12–27 August 2003, 6–20 August 2004). The measurements were performed simultaneously at distances of 9 m and 65 m from the highway. Total number concentrations were measured by a condensation particle counter (CPC) and particle size distributions by a scanning mobility particle sizer (SMPS) and an electrical low pressure impactor (ELPI). This study concentrates on data that were measured when the wind direction was from the road to the measurement site. The total concentrations in the wintertime were 2–3 times higher than in the summertime and the concentrations were dominated by nucleation mode particles. The particles smaller than 63 nm (aerodynamic diameter) constituted ~90% of all particles in the wintertime and ~80% of particles in the summer time. The particle total concentration increased with increasing traffic rate. The effect of traffic rate on particles smaller than 63 nm was stronger than on the larger particles. The particle distributions at the roadside consisted of two distinguishable modes. The geometric mean diameter (GMD) of nucleation mode (Mode 1) was 20.3 nm in summer and 18.9 nm in winter. The GMD of the larger mode consisting mostly of traffic related soot particles (Mode 2) was 72.0 nm in summer and 75.1 nm in winter. The GMD values of the modes did not depend on the traffic rate. The average particle density for each mode was determined by a parallel density fitting method based on the size distribution measurement made by ELPI and SMPS. The average density value for Mode 1 particles was 1.0±0.13 g/cm 3 and 1.0±0.07 g/cm 3 both in summer and winter respectively, while the average density value for Mode 2 was 1.5±0.1 g/cm 3 and 1.8±0.3 g/cm 3 for summer and winter, respectively.