Modeling interfacial liquid layers on environmental ices Department of Chemical Engineering, Columbia University, New York, New York 10027, USA
28 Sep 2011
Received: 08 February 2011 – Published in Atmos. Chem. Phys. Discuss.: 10 March 2011 Abstract. Interfacial layers on ice significantly influence air-ice chemical
interactions. In solute-containing aqueous systems, a liquid brine may form
upon freezing due to the exclusion of impurities from the ice crystal
lattice coupled with freezing point depression in the concentrated brine.
The brine may be segregated to the air-ice interface where it creates a
surface layer, in micropockets, or at grain boundaries or triple junctions.
Revised: 12 September 2011 – Accepted: 12 September 2011 – Published: 28 September 2011
We present a model for brines and their associated liquid layers in
environmental ice systems that is valid over a wide range of temperatures
and solute concentrations. The model is derived from fundamental equlibrium
thermodynamics and takes into account nonideal solution behavior in the
brine, partitioning of the solute into the ice matrix, and equilibration
between the brine and the gas phase for volatile solutes. We find that these
phenomena are important to consider when modeling brines in environmental
ices, especially at low temperatures. We demonstrate its application for
environmentally important volatile and nonvolatile solutes including NaCl,
HCl, and HNO3. The model is compared to existing models and
experimental data from literature where available. We also identify
environmentally relevant regimes where brine is not predicted to exist, but
the QLL may significantly impact air-ice chemical interactions. This model
can be used to improve the representation of air-ice chemical interactions
in polar atmospheric chemistry models.
Citation: Kuo, M. H., Moussa, S. G., and McNeill, V. F.: Modeling interfacial liquid layers on environmental ices, Atmos. Chem. Phys., 11, 9971-9982, doi:10.5194/acp-11-9971-2011, 2011.