Hydrophobic and hydrophilic properties of pollutants as a factor influencing their redistribution during snowpack melt.

Glaciers accumulate organic pollutants delivered by snow. However, our understanding of the exact dynamics of organic pollutants in the snowpack relies primarily on laboratory experiments and mathematical models. To fill the gap related to the detailed field data, we have conducted observations of melting snow profiles in two locations and three different stages of melting on one High Arctic glacier, as well as in superimposed ice. We monitored the chemical concentrations of formaldehyde, phenols, short-chain carboxylic acids, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) and snow water equivalents to derive chemical loads. The obtained organic contaminant redistribution patterns are compared to the meltwater removal model by Meyer and Wania (2011), in order to link the behaviour of chemicals to their hydrophilic or hydrophobic properties. Both the later snowpits and the superimposed ice layer were generally more abundant in particulate organics and hydrophobic compounds, despite the initial prevalence of hydrophilic organic chemicals. The chemical species with high water solubility also showed less predictable elution patterns, due to their chemical reactivity and possible photochemical reactions in the snowpack. Finally, ice layers in the snowpack showed very different chemical characteristics to the underlying superimposed ice, so one cannot be used as a chemical proxy for another. In order to interpret the ice core records correctly, the temporal changes in concentration of different pollutant types should be considered, as glaciers may preferentially accumulate hydrophobic organics that tarry in the snow cover.