Abstract: In this study, the hygroscopicity of submicron particles was studied from September to October in Mt. Huangshan. A Humidity Tandem Differential Mobility Analyser (H-TDMA) instrument was applied to measure the hygroscopic growth factor (GF) at different altitudes for particles with dry diameter between 40-200 nm. The statistical results show that, the GFs of the aerosol show a distinct bimodal distribution, and classified into less-hygroscopic (LH) group (GF＜1.15)and more-hygroscopic (MH) group(GF＞1.15). The spread of GF-PDF (σ) are higher in more-hygroscopic group than in less-hygroscopic group with the same size. The change of relative humidity has an effect on particle hygroscopic growth which is associated with particle size and chemical compositions. Aitken nuclei and condensation nuclei have different deliquescence point under the same relative humidity. The main moisture absorption components are ammonium nitrate and ammonium sulfate. Mt. Huangshan is clean and pollution emission source is unitary. the experiment set relative humidity is 85% which is lower than in other places. So the hygroscopicity is less than in the city area. By comparing the hygroscopic growth factor of aerosol particles under the different altitudes, it is found that with increasing altitude, hygroscopicity of particulate matter is reduced.
Key words：aerosol particles; hygroscopic growth; H-TDMA; Mt. Huangshan