In recent years, significant evidence has accumulated suggesting that the geochemical transformations of dissolved organic matter in marine waters is mediated in large measure by light and trace metal catalysis. In this project the principal investigator will conduct a comprehensive study of the kinetics of photooxidation of chromophoric (i.e., colored) dissolved organic matter (CDOM) in coastal waters. Laboratory studies will be conducted in the presence and absence of various radical scavengers and oxygen and interpreted using kinetic modeling. To study the involvement of hydroxide radical, hydroxide would be generated chemically or radiolytically in the absence of light. The specific topics that will be addressed include: (1) the importance of Fe in CDOM photooxidation, photobleaching and product formation in seawater; (2) the photomechanism of CDOM bleaching in the absence of Fe; and (3) the mechanisms of Fe-CDOM interactions.
