1Laboratory of Radio and Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
2CNRS, Laboratoire de Glaciologie et Géophysique de l'Environnement (UMR5183), 38041 Grenoble, France
3Univ. Grenoble Alpes, LGGE (UMR5183), 38041 Grenoble, France
4Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, Syracuse, New York, USA
5UPMC Univ. Paris 06, UMR8190, CNRS/INSU – Univ. Versailles St.-Quentin, LATMOS-IPSL, Paris, France
6University of California, Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA 90095, USA
7Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, 41296, Gothenburg, Sweden
8Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON, M5S 3H6, Canada
9Institute for Materials and Processes, School of Engineering, King's Buildings, The University of Edinburgh, EH9 3JL, UK
10Lawrence Berkeley National Laboratory, Chemical Sciences Division, Berkeley, CA 94720, USA
11Department of Chemistry and Environmental Science, Medgar Evers College – City University of New York, Brooklyn, NY 11235, USA
12City University of New York, Graduate Center, Department of Chemistry, Department of Earth & Environmental Sciences, Manhattan, NY 10016, USA
13Takuvik Joint International Laboratory, Université Laval and CNRS, and Department of Chemistry, 1045 avenue de la médecine, Québec, QC, G1V 0A6, Canada
14British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
15Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, 16610 Prague 6, Czech Republic
16Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055, USA
17Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A, 62500 Brno, Czech Republic
18RECETOX, Faculty of Science, Masaryk University, Kamenice 3, 62500 Brno, Czech Republic
19SLS Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
20GZG Abt. Kristallographie, Universität Göttingen, Goldschmidtstr. 1, 37077 Göttingen, Germany
21Department of Chemical Engineering, Columbia University, New York, NY, USA
22Geophysical Institute, University Bergen, 5007 Bergen, Norway
23Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA
24Department of Chemistry and Environmental Research Institute, University College Cork, Cork, Ireland
Received: 28 Sep 2012 – Discussion started: 26 Nov 2012
Abstract. Snow in the environment acts as a host to rich chemistry and provides a matrix for physical exchange of contaminants within the ecosystem. The goal of this review is to summarise the current state of knowledge of physical processes and chemical reactivity in surface snow with relevance to polar regions. It focuses on a description of impurities in distinct compartments present in surface snow, such as snow crystals, grain boundaries, crystal surfaces, and liquid parts. It emphasises the microscopic description of the ice surface and its link with the environment. Distinct differences between the disordered air–ice interface, often termed quasi-liquid layer, and a liquid phase are highlighted. The reactivity in these different compartments of surface snow is discussed using many experimental studies, simulations, and selected snow models from the molecular to the macro-scale.
Revised: 06 Nov 2013 – Accepted: 13 Dec 2013 – Published: 12 Feb 2014
Although new experimental techniques have extended our knowledge of the surface properties of ice and their impact on some single reactions and processes, others occurring on, at or within snow grains remain unquantified. The presence of liquid or liquid-like compartments either due to the formation of brine or disorder at surfaces of snow crystals below the freezing point may strongly modify reaction rates. Therefore, future experiments should include a detailed characterisation of the surface properties of the ice matrices. A further point that remains largely unresolved is the distribution of impurities between the different domains of the condensed phase inside the snowpack, i.e. in the bulk solid, in liquid at the surface or trapped in confined pockets within or between grains, or at the surface. While surface-sensitive laboratory techniques may in the future help to resolve this point for equilibrium conditions, additional uncertainty for the environmental snowpack may be caused by the highly dynamic nature of the snowpack due to the fast metamorphism occurring under certain environmental conditions.
Due to these gaps in knowledge the first snow chemistry models have attempted to reproduce certain processes like the long-term incorporation of volatile compounds in snow and firn or the release of reactive species from the snowpack. Although so far none of the models offers a coupled approach of physical and chemical processes or a detailed representation of the different compartments, they have successfully been used to reproduce some field experiments. A fully coupled snow chemistry and physics model remains to be developed.
Bartels-Rausch, T., Jacobi, H.-W., Kahan, T. F., Thomas, J. L., Thomson, E. S., Abbatt, J. P. D., Ammann, M., Blackford, J. R., Bluhm, H., Boxe, C., Domine, F., Frey, M. M., Gladich, I., Guzmán, M. I., Heger, D., Huthwelker, Th., Klán, P., Kuhs, W. F., Kuo, M. H., Maus, S., Moussa, S. G., McNeill, V. F., Newberg, J. T., Pettersson, J. B. C., Roeselová, M., and Sodeau, J. R.: A review of air–ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow, Atmos. Chem. Phys., 14, 1587-1633, doi:10.5194/acp-14-1587-2014, 2014.