| The first part of this thesis focuses on the photosensitized degradation of lignin model compounds. The kinetics and mechanism of the photodegradation of monomeric and dimeric models of lignin that vary in their number of methoxy substituents is described. Specifically, the kinetics of the reaction of lignin models with singlet oxygen and excited sensitizer (both are reactive species present in sunlit natural waters) is reported and used to elucidate the mechanism of these reactions. The second part of this thesis focuses on the quantification of the generation of singlet oxygen by natural organic matter in Lake Superior and its Western tributaries. Furfuryl alcohol, whose primary photochemical reaction is with singlet oxygen has been used to quantify the production of singlet oxygen from water sources collected from the lake and tributaries four different times throughout the summer of 2005. A correlation between singlet oxygen occurrence, spectral properties, and size is described. In part three of this thesis, the degradation of organic matter due to reaction with singlet oxygen is examined. Sensitox II, a water-swellable resin with bound Rose Bengal has been synthesized and used in the reaction of dissolved organic matter with singlet oxygen. The observed photobleaching and formation of low molecular weight products is described here. |
