title: Estimation of size-resolved ambient particle density based on the measurement of aerosol number, mass, and chemical size distributions in the winter in Beijing.
abstract: Simultaneous measurements of aerosol size, distribution of number, mass, and chemical compositions were conducted in the winter of 2007 in Beijing using a Twin Differential Mobility Particle Sizer and a Micro Orifice Uniform Deposit Impactor. Both material density and effective density of ambient particles were estimated to be 1.61 ± 0.13 g cm(-3) and 1.62 ± 0.38 g cm(-3) for PM(1.8) and 1.73 ± 0.14 g cm(-3) and 1.67 ± 0.37 g cm(-3) for PM(10). Effective density decreased in the nighttime, indicating the primary particles emission from coal burning influenced the density of ambient particles. Size-resolved material density and effective density showed that both values increased with diameter from about 1.5 g cm(-3) at the size of 0.1 μm to above 2.0 g cm(-3) in the coarse mode. Material density was significantly higher for particles between 0.56 and 1.8 μm during clean episodes. Dynamic Shape Factors varied within the range of 0.95-1.13 and decreased with particle size, indicating that coagulation and atmospheric aging processes may change the shape of particles.
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, People's Republic of China. minhu@pku.edu.cn
authors.forename: Min
authors.initials: M
authors.lastname: Hu
authors.forename: Jianfei
authors.initials: J
authors.lastname: Peng
authors.forename: Kang
authors.initials: K
authors.lastname: Sun
authors.forename: Dingli
authors.initials: D
authors.lastname: Yue
authors.forename: Song
authors.initials: S
authors.lastname: Guo
authors.forename: Alfred
authors.initials: A
authors.lastname: Wiedensohler
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Wu
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis*; D002681:China; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter