Effective Density and Mixing State of Aerosol Particles in a Near-Traffic Urban Environment

详细信息    查看全文

• 作者：Jenny Rissler ; Erik Z. Nordin ; Axel C. Eriksson ; Patrik T. Nilsson ; Mia Frosch ; Moa K. Sporre ; Aneta Wierzbicka ; Birgitta Svenningsson ; Jakob L枚ndahl ; Maria E. Messing ; Staffan Sjogren ; Jette G. Hemmingsen ; Steffen Loft ; Joakim H. Pagels ; Erik Swietlicki
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：June 3, 2014
• 年：2014
• 卷：48
• 期：11
• 页码：6300-6308
• 全文大小：466K
• 年卷期：v.48,no.11(June 3, 2014)
• ISSN：1520-5851

文摘

In urban environments, airborne particles are continuously emitted, followed by atmospheric aging. Also, particles emitted elsewhere, transported by winds, contribute to the urban aerosol. We studied the effective density (mass-mobility relationship) and mixing state with respect to the density of particles in central Copenhagen, in wintertime. The results are related to particle origin, morphology, and aging. Using a differential mobility analyzer-aerosol particle mass analyzer (DMA-APM), we determined that particles in the diameter range of 50鈥?00 nm were of two groups: porous soot aggregates and more dense particles. Both groups were present at each size in varying proportions. Two types of temporal variability in the relative number fraction of the two groups were found: soot correlated with intense traffic in a diel pattern and dense particles increased during episodes with long-range transport from polluted continental areas. The effective density of each group was relatively stable over time, especially of the soot aggregates, which had effective densities similar to those observed in laboratory studies of fresh diesel exhaust emissions. When heated to 300 掳C, the soot aggregate volatile mass fraction was 10%. For the dense particles, the volatile mass fraction varied from 80% to nearly 100%.