Artificial and natural fluorescence of dissolved organic matter in the Tampa Bay Estuary

The fluorescence of colored dissolved organic matter (CDOM) was studied in the Tampa Bay estuary using excitation-emission matrix spectroscopy (EEMS). Results of statistical tests indicated that CDOM varied within the estuary based on significant differences between location, season, and marine influence. Results also indicated that the two fluorescence peaks identified in this study varied independently of each other, implying that each peak possess a different composition of a potentially large number of fluorophores.; High energy laser fragmentation (HELF) was combined with EEMS to study the photodegradation of CDOM in rivers feeding the Tampa Bay estuary using monochromatic light. Results presented as loss spectra showed fluorescent material destroyed had two distinct peaks for all samples at all degradation wavelengths of 320 nm or greater. In contrast to spectra for the initial and residual fingerprints, loss spectra showed the rounded contours expected for a pure organic fluorophore. These observations suggest that laser irradiation targets a specific fluorophore or restricted group of fluorophores in the original mixture, some of which have a double excitation maximum and single emission maximum. By varying the degradation wavelength, eight distinct fluorophore groups were identified in the sample set.; The use of HELF allowed not only the study of CDOM photodegradation, but also provided useful insight into the composition of the original CDOM which aided to the selection of potential fluorescent proxies. These proxies were also analyzed using HELF, and results supported the conclusion that the peak shape and position of fluorescence loss peaks correspond to the fluorescence properties of the fluorophores removed by each λ_deg. Absorbance and fluorescence photoproducts were identified from each of the proxies, providing characterization of the photochemical reactivity of the proxies studied.; Finally, the fluorescence of plastics and epoxy-based mine materials were examined and compared with CDOM fluorescence with the purpose of developing a fluorescence based detection system optimized for the recognition of underwater mine materials and plastics in the aquatic environment. The method would have wide ranging applications as bisphenol A, identified as a chemical surrogate for plastics fluorescence in the environment, is a recognized health concern due to its properties as an endocrine disrupter.