It is well established that ice is a reactive medium in the environment and that active photochemistry occurs in frozen systems.  Snow and ice contain a number of absorbing species including nitrate, nitrite, peroxide, and organic matter.  These generate a variety of reactive intermediates upon radiation, such as hydroxyl radical and singlet oxygen.  Dissolved organic matter (DOM) is a ubiquitous component of snow and ice and plays an important role in overall light absorption properties of the sample.  Additionally, the reactive intermediates produced by DOM photolysis can further react with contaminants present and alter their fate in the environment or may play a role in generation and emission of volatile species to the overlying atmosphere.  Unfortunately, the role of DOM in ice photochemistry has received little attention, and characterizing the nature of DOM is hindered due to its complex and heterogeneous nature.  Using ices generated under controlled laboratory conditions we have found that the production of reactive oxygen species from DOM photolysis is enhanced in ice compared to liquid water, and this production significantly influences the fate of organic contaminants in ice.  We will also discuss here advances in the characterization of DOM using advanced analytical techniques such as ultra-high resolution mass spectrometry and NMR.

Natural organic matter as an important photosensitizer in snow and ice

248th National Meeting (2014)

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