Contribution of gaseous and particulate species to droplet solute composition at the Puy de Dôme, France K. Sellegri1, P. Laj1, A. Marinoni1, R. Dupuy1, M. Legrand2, and S. Preunkert2 1Laboratoire de Meteorologie Physique, CNRS, Université Blaise Pascal, 24, av; des landais 63 177 Aubiere cedex, France 2Laboratoire de Glaciologie et Géophysique de l’Environnement, 54, rue Molière, 38402 St Martin d’Hères cedex, France
Abstract. Chemical reactions of dissolved gases in the liquid phase play a key role in atmospheric
processes both in the formation of secondary atmospheric compounds and their wet removal
rate but also in the regulation of the oxidizing capacity of the troposphere. The behavior of
gaseous species and their chemical transformation in clouds are difficult to observe
experimentally given the complex nature of clouds.
During a winter field campaign at the summit of the Puy de Dôme (central France,
1465 m a.s.l), we have deployed an experimental set-up to provide a quantification of phase
partitioning of both organic (CH3COOH, HCOOH, H2C2O4) and inorganic
(NH3, HNO3, SO2, HCl) species in clouds.
We found that nitric and hydrochloric acids can be considered close to Henry's law
equilibrium, within analytical uncertainty and instrumental errors. On another hand, for
NH3 and carboxylic acids, dissolution of material from the gas phase is kinetically limited and
never reaches the equilibrium predicted by thermodynamics, resulting in significant
sub-saturation of the liquid phase. On the contrary, SIV is supersaturated in the liquid phase, in
addition to the presence of significant aerosol-derived SVI transferred through nucleation
Upon droplet evaporation, a significant part of most species, including SIV, tends to
efficiently return back into the gas phase. Overall, gas contribution to the droplet solute
concentration ranges from at least 48.5 to 98% depending on the chemical species. This is
particularly important considering that aerosol scavenging efficiencies are often calculated
assuming a negligible gas-phase contribution to the solute concentration. Our study
emphasizes the need to account for the in-cloud interaction between particles and gases to
provide an adequate modeling of multiphase chemistry systems and its impact on the
atmospheric aerosol and gas phases.
Citation: Sellegri, K., Laj, P., Marinoni, A., Dupuy, R., Legrand, M., and Preunkert, S.: Contribution of gaseous and particulate species to droplet solute composition at the Puy de Dôme, France, Atmos. Chem. Phys., 3, 1509-1522, doi:10.5194/acp-3-1509-2003, 2003.