Photooxidation DOM- Carboxylic acids

Photochemical reactions are affected not only by the DOM reactants but also by key inorganic species (such as carbonate, halogen radicals, nitrate, and nitrite). Therefore we propose to investigate DOM photochemistry in two different aquatic systems with differing salinities and nitrate and nitrite levels, but similar concentration ranges of dissolved organic carbon and chromophoric dissolved organic matter, and similar pH ranges. Using these two transects from highly allochthonous to autochthonous DOM, which cover a wide range of DOM quantity and quality, we propose to study the photochemical transformations of DOM carboxyl groups. We will investigate how the phototransformations of these carboxyl groups vary along the two environmental-effect axes of salinity and DOM source.