Abstract
We measured ion migration in a four-week period within artificial snow layers, including an impurity layer containing Na+, Mg2+, SO4 2−, NO3−, in a temperature controlled chamber; temperature was controlled to just below the melting point. At temperatures lower than−0.20℃，the positions of peak ion concentration did not change, but a small quantity of ions migrated both downwards and upwards. The ranking of mobility of different ions was: Na+ > Mg2+ > SO4 2− > NO3−, and there was no change with time. When temperature was closer to the melting point of snow, the positions of all ion concentration peaks shifted to downwards, and some ion peaks became broader with time, in the following order: Na+ > Mg2+ > SO4 2−. However, NO3− did not migrate over time. These phenomena were caused by differences in ionic radii, adsorption energy, and adsorption site on the ice surface.
