||Volatile pollutants evaporate from lower, warmer latitudes and condense out in the higher, colder latitudes by a process known as global distillation, leading to enhanced concentrations of a variety of pollutants in polar regions. This could potentially result in negative impacts on Arctic ecosystems due to bioaccumulation effects. To date little is known about the reactivity of organic pollutants in snow and ice. This thesis presents recent results of photochemical degradation studies of several important organic pollutants including aldrin, dieldrin, hexachlorobenzene, and 3,3',4,5'-tetrachlorobiphenyl. Direct and indirect (with H 2 O 2 ) photochemical pathways were studied in both liquid water and ice forms. Comparisons of liquid reactivity in liquid water and ice indicate that the organic is trapped in the bulk ice and not segregated to the surface quasi-liquid layer. Reactivity is a function of temperature, pH, and freezing methods. Initial product identification suggests that products can be more toxic than the starting pollutant.