Size dependence of in situ pH in submicron atmospheric particles in Hong Kong

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

Detail(s)

Original languageEnglish
Pages (from-to)382-393
Journal / PublicationAtmospheric Environment
Volume41
Issue number2
Publication statusPublished - Jan 2007
Externally publishedYes

Abstract

Some studies have reported that small submicron atmospheric particles are more acidic than large submicron particles; other studies demonstrated a reversed trend. In this study, the size dependence of in situ pH in submicron particles in Hong Kong was investigated. The equivalent ratios of [NH4 +]measured to [SO4 2-]measured in submicron particles were found to be generally less than unity and size dependent, suggesting the possibility of incomplete gas-aerosol equilibrium. The Aerosol Inorganic Model-II (AIM-II) model using measured ionic compositions with the gas-aerosol partitioning disabled was used to estimate the in situ pH in different sized particles. The estimated in situ pH of different sized submicron atmospheric particles was between -2.5 and 1.5 and it generally decreases with increasing submicron particle size. At such low in situ pH, the estimated HSO4 - equivalent concentrations were 3.2 times (on average) of those of H+ in different sized particles. The trends of the size dependence of the [NH4 +]measured to [SO4 2-]measured ratio and pH under different regimes of relative humidity are discussed. © 2006 Elsevier Ltd. All rights reserved.

Research Area(s)

  • Aerosol acidity, Aerosol thermodynamics, AIM, Gas-aerosol partitioning, Hong Kong, Water content

Citation Format(s)

Size dependence of in situ pH in submicron atmospheric particles in Hong Kong. / Yao, Xiaohong; Ling, Tsz Yan; Fang, Ming; Chan, Chak K.

In: Atmospheric Environment, Vol. 41, No. 2, 01.2007, p. 382-393.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review