Photochemical transformations in ice: Implications for the fate of chemical species

A quantum yield of phi (ice) = 2.3 x 10(-4) (+/- 4 x 10(-5)) was determined for the photochemical degradation of 4-nitrophenol over the wavelength ran ge of 300 to 370 nm in ice pellets (pH 5.6). Five reaction products were id entified: hydroquinone, benzoquinone, 4-nitrosophenol, nitrate, nitrite, an d the likely formation of organic polymers. The similarities of these resul ts to the observations from 4-nitrophenol photolysis in aqueous solutions i ndicate that similar mechanisms are operative in both phases. The photochem ical decomposition of 4-nitrophenol under conditions similar to those in po lar snow and ice suggests that other direct and indirect photochemical proc ess can occur in the polar ice/snow during spring and summer.