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 journal › peer-review
Author(s)
Detail(s)
Original language | English |
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Pages (from-to) | 382-393 |
Journal / Publication | Atmospheric Environment |
Volume | 41 |
Issue number | 2 |
Publication status | Published - Jan 2007 |
Externally published | Yes |
Link(s)
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 journal › peer-review