||Polar regions are impacted by organic contaminants and photochemical degradation may be an important pathway in Arctic environments. Here, the photochemical degradation rates of the historical use pesticide, aldrin, were investigated in liquid and ice samples. Indirect photochemical processes were also evaluated by the addition of natural organic matter to aldrin solutions. It was found that frozen samples of aldrin degrade more quickly than liquid samples, by a factor of 2 for direct photolysis experiments and by a factor ranging from 2 to 56 for indirect photochemical processes. It was also found that aldrin is degraded via singlet oxygen chemistry. Results from experiments investigating the role of temperature were inconclusive due to the scatter in the measured aldrin half-lives. Overall, the results indicate that pollutant photochemical degradation mediated by dissolved organic matter in frozen systems may play an important role in the fate of compounds in polar regions.