Particle number size distribution and new particle formation (NPF) in Lanzhou, Western China--颗粒学报PARTICUOLOGY

Gao, J., Chai, F., Wang, T., & Wang, W. (2011). Particle number size distribution and new particle formation (NPF) in Lanzhou, Western China. Particuology, 9(6), 611–618. https://doi.org/10.1016/j.partic.2011.06.008

Particle number size distribution and new particle formation (NPF) in Lanzhou, Western China

Jian Gao ^a *, Fahe Chai ^a, Tao Wang ^{a b}, Wenxing Wang ^a

a State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Science, Beijing 100012, China
b Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, HongKong, China

10.1016/j.partic.2011.06.008

Volume 9, Issue 6, December 2011, Pages 611-618

Received 20 September 2010, Revised 31 May 2011, Accepted 9 June 2011, Available online 9 November 2011.

E-mail: gaojian@craes.org.cn

Highlights

Abstract

Particle number size distribution from 10 to 10,000 nm was measured by a wide-range particle spectrometer (WPS-1000XP) at a downwind site north of downtown Lanzhou, western China, from 25 June to 19 July 2006. We first report the pollution level, diurnal variation of particle concentration in different size ranges and then introduce the characteristics of the particle formation processes, to show that the number concentration of ultrafine particles was lower than the values measured in other urban or suburban areas in previous studies. However, the fraction of ultrafine particles in total aerosol number concentration was found to be much higher. Furthermore, sharp increase of ultrafine particle concentration was frequently observed at noon. An examination of the diurnal pattern suggests that the burst of the ultrafine particles was mainly due to nucleation process. During the 25-day observation, new particle formation (NPF) from homogeneous nucleation was observed during 33% of the study period. The average growth rate of the newly formed particles was 4.4 nm/h, varying from 1.3 to 16.9 nm/h. The needed concentration of condensable vapor was 6.1 × 107 cm⁻³, and its source rate was 1.1 × 106 cm⁻³ s⁻¹. Further calculation on the source rate of sulphuric acid vapor indicated that the average participation of sulphuric acid to particle growth rate was 68.3%.

Graphical abstract

Keywords

Lanzhou; New particle formation (NPF); Number size distribution; Particle growth rate; Sulphuric acid

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