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

Jian Gao, Fahe Chai, Tao Wang, Wenxing Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

31 Citations (Scopus)


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 × 107cm-3, and its source rate was 1.1 × 106cm-3s-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%.
Original languageEnglish
Pages (from-to)611-618
Number of pages8
Issue number6
Publication statusPublished - 1 Dec 2011


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

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Materials Science(all)
  • Condensed Matter Physics

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