High solubility of SO2: evidence in an intensive fog event measured in the NCP region, China
Item
Title (Dublin Core)
High solubility of SO2: evidence in an intensive fog event measured in the NCP region, China
Description (Dublin Core)
A field experiment was conducted in a heavy SO<sub>2</sub> pollution area located in north China plain (NCP). During the experiment, SO<sub>2</sub> and other air pollutants, liquid water content (LWC) of fog droplets, and basic meteorological parameters were measured. During the experiment, an intensive fog event occurred between 5 and 8 November 2009. During the fog period, the concentrations of SO<sub>2</sub> showed a strong variability, and the variability was closely correlated to the appearances of fogs and LWC. For example, the averaged concentration of SO<sub>2</sub> during the non-fog period was about 25 ppbv. By contrast, during the fog period, the concentration of SO<sub>2</sub> reduced to about 4–7 ppbv. The large reduction of SO<sub>2</sub> suggests that a majority of SO<sub>2</sub> (about 70–80%) had been converted from gas-phase to aqueous-phase, showing a high solubility of SO<sub>2</sub>. However, according to the value of Henry Law constant, the solubility of SO<sub>2</sub> is modest, which cannot explain the measured large reduction of SO<sub>2</sub>. This study highlights that the aqueous reactions of SO<sub>2</sub> in the droplets of fogs play important roles to enhance the solubility of SO<sub>2</sub>. To account for the effect of aqueous reactions on the solubility of SO<sub>2</sub>, an "effective" Henry Law constant of SO<sub>2</sub> is proposed in this study. The study shows that without considering aqueous reactions of SO<sub>2</sub> in fog droplets, the estimate of the partitioning of SO<sub>2</sub> in droplets is significantly lower than the measured values. By contrast, when the "effective" Henry Law constant is applied in the calculation, the calculated SO<sub>2</sub> concentrations are significantly improved, showing that the aqueous reactions of SO<sub>2</sub> play important roles in controlling the solubility of SO<sub>2</sub>, and should be considered in model calculations.
Creator (Dublin Core)
Zhang, Q.
Tie, X.
Date (Dublin Core)
2018-08-10
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acpd-11-2931-2011
https://acp.copernicus.org/preprints/acp-2011-25/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
