Mass Transport of Gases across the Air-Water Interface: Implications for Aldehyde Emissions in the Uinta Basin, Utah, USA

When they dissolve in water, aldehydes become hydrated to gem-diols: R-COH+H2O <-> RCH(OH)2. Such reactions can complicate air-water transport models. Because of a persistent belief that the gem-diols do not exist in the vapor phase, typical models do not allow them to pass through the air-water interface, but in fact, they do. Therefore, transport models that allow both molecular forms to exist in both phases and to pass through the interface are needed. Such a model is presented here as a generalization of Whitman's two-film model. Since Whitman's model has fallen into disuse, justification of its use is also given. There are hypothetical instances for which the flux predicted by the current model is significantly larger than the flux predicted when models forbid the diol form from passing through the interface. However, for formaldehyde and acetaldehyde, the difference is about 6% and 2%, respectively.